diff --git a/doc/tutorial/Makefile b/doc/tutorial/Makefile index 5c397e78d..0a3517bff 100644 --- a/doc/tutorial/Makefile +++ b/doc/tutorial/Makefile @@ -1,39 +1,150 @@ -TEXI2HTML = texi2html -TEXI2PDF = texi2dvi --pdf -EPSTOPDF = epstopdf +# Makefile for Sphinx documentation +# + +# You can set these variables from the command line. +SPHINXOPTS = +SPHINXBUILD = sphinx-build +PAPER = +BUILDDIR = build + +# Internal variables. +PAPEROPT_a4 = -D latex_paper_size=a4 +PAPEROPT_letter = -D latex_paper_size=letter +ALLSPHINXOPTS = -d $(BUILDDIR)/doctrees $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) source + +# Additional variables for figures, not sphinx default: DIA = dia -CONVERT = convert -CSS = --css-include=tutorial.css -SPLIT = --split section +EPSTOPDF = epstopdf +FIGURES = source/figures +IMAGES_EPS = \ -DIA_SOURCES = pp.dia dumbbell.dia star.dia +IMAGES_PNG = ${IMAGES_EPS:.eps=.png} +IMAGES_PDF = ${IMAGES_EPS:.eps=.pdf} -DIA_EPS = ${DIA_SOURCES:.dia=.eps} -DIA_PNG = ${DIA_SOURCES:.dia=.png} -DIA_PDF = ${DIA_SOURCES:.dia=.pdf} +IMAGES = $(IMAGES_EPS) $(IMAGES_PNG) $(IMAGES_PDF) -all: html split-html pdf +.PHONY: help clean html dirhtml singlehtml pickle json htmlhelp qthelp devhelp epub latex latexpdf text man changes linkcheck doctest -# Note: tgif requires a valid x display to convert from .obj to .png. -# If running this makefile on a remote console, the X virtual frame -# buffer may be needed (xorg-x11-server-Xvfb) to provide a "fake" -# display -images: - cd figures/; $(DIA) -t png $(DIA_SOURCES) - cd figures/; $(DIA) -t eps $(DIA_SOURCES) - cd figures/; $(foreach FILE,$(DIA_EPS),$(EPSTOPDF) $(FILE);) +%.eps : %.dia; $(DIA) -t eps $< -e $@ +%.png : %.dia; $(DIA) -t png $< -e $@ +%.pdf : %.eps; $(EPSTOPDF) $< -o=$@ -html: - $(TEXI2HTML) ${CSS} tutorial.texi +help: + @echo "Please use \`make ' where is one of" + @echo " html to make standalone HTML files" + @echo " dirhtml to make HTML files named index.html in directories" + @echo " singlehtml to make a single large HTML file" + @echo " pickle to make pickle files" + @echo " json to make JSON files" + @echo " htmlhelp to make HTML files and a HTML help project" + @echo " qthelp to make HTML files and a qthelp project" + @echo " devhelp to make HTML files and a Devhelp project" + @echo " epub to make an epub" + @echo " latex to make LaTeX files, you can set PAPER=a4 or PAPER=letter" + @echo " latexpdf to make LaTeX files and run them through pdflatex" + @echo " text to make text files" + @echo " man to make manual pages" + @echo " changes to make an overview of all changed/added/deprecated items" + @echo " linkcheck to check all external links for integrity" + @echo " doctest to run all doctests embedded in the documentation (if enabled)" -split-html: - $(TEXI2HTML) ${CSS} ${SPLIT} --output tutorial tutorial.texi +clean: + -rm -rf $(BUILDDIR)/* -pdf: - $(TEXI2PDF) tutorial.texi +frag: pickle + @if test ! -d $(BUILDDIR)/frag; then mkdir $(BUILDDIR)/frag; fi + pushd $(BUILDDIR)/frag && ../../pickle-to-xml.py ../pickle/index.fpickle > navigation.xml && popd + cp -r $(BUILDDIR)/pickle/_images $(BUILDDIR)/frag -figures-clean: - cd figures/; rm -rf $(DIA_EPS); rm -rf $(DIA_PNG); rm -rf $(DIA_PDF) +html: $(IMAGES) + $(SPHINXBUILD) -b html $(ALLSPHINXOPTS) $(BUILDDIR)/html + @echo + @echo "Build finished. The HTML pages are in $(BUILDDIR)/html." -clean: # figures-clean - rm -rf tutorial.aux tutorial.cp tutorial.cps tutorial.fn tutorial.ky tutorial.pg tutorial.tp tutorial.vr tutorial.toc tutorial.log tutorial.pdf tutorial.html tutorial/ +dirhtml: $(IMAGES) + $(SPHINXBUILD) -b dirhtml $(ALLSPHINXOPTS) $(BUILDDIR)/dirhtml + @echo + @echo "Build finished. The HTML pages are in $(BUILDDIR)/dirhtml." + +singlehtml: $(IMAGES) + $(SPHINXBUILD) -b singlehtml $(ALLSPHINXOPTS) $(BUILDDIR)/singlehtml + @echo + @echo "Build finished. The HTML page is in $(BUILDDIR)/singlehtml." + +pickle: $(IMAGES) + $(SPHINXBUILD) -b pickle $(ALLSPHINXOPTS) $(BUILDDIR)/pickle + @echo + @echo "Build finished; now you can process the pickle files." + +json: $(IMAGES) + $(SPHINXBUILD) -b json $(ALLSPHINXOPTS) $(BUILDDIR)/json + @echo + @echo "Build finished; now you can process the JSON files." + +htmlhelp: $(IMAGES) + $(SPHINXBUILD) -b htmlhelp $(ALLSPHINXOPTS) $(BUILDDIR)/htmlhelp + @echo + @echo "Build finished; now you can run HTML Help Workshop with the" \ + ".hhp project file in $(BUILDDIR)/htmlhelp." + +qthelp: $(IMAGES) + $(SPHINXBUILD) -b qthelp $(ALLSPHINXOPTS) $(BUILDDIR)/qthelp + @echo + @echo "Build finished; now you can run "qcollectiongenerator" with the" \ + ".qhcp project file in $(BUILDDIR)/qthelp, like this:" + @echo "# qcollectiongenerator $(BUILDDIR)/qthelp/ns-3.qhcp" + @echo "To view the help file:" + @echo "# assistant -collectionFile $(BUILDDIR)/qthelp/ns-3.qhc" + +devhelp: $(IMAGES) + $(SPHINXBUILD) -b devhelp $(ALLSPHINXOPTS) $(BUILDDIR)/devhelp + @echo + @echo "Build finished." + @echo "To view the help file:" + @echo "# mkdir -p $$HOME/.local/share/devhelp/ns-3" + @echo "# ln -s $(BUILDDIR)/devhelp $$HOME/.local/share/devhelp/ns-3" + @echo "# devhelp" + +epub: $(IMAGES) + $(SPHINXBUILD) -b epub $(ALLSPHINXOPTS) $(BUILDDIR)/epub + @echo + @echo "Build finished. The epub file is in $(BUILDDIR)/epub." + +latex: $(IMAGES) + $(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex + @echo + @echo "Build finished; the LaTeX files are in $(BUILDDIR)/latex." + @echo "Run \`make' in that directory to run these through (pdf)latex" \ + "(use \`make latexpdf' here to do that automatically)." + +latexpdf: $(IMAGES) + $(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex + @echo "Running LaTeX files through pdflatex..." + make -C $(BUILDDIR)/latex all-pdf + @echo "pdflatex finished; the PDF files are in $(BUILDDIR)/latex." + +text: $(IMAGES) + $(SPHINXBUILD) -b text $(ALLSPHINXOPTS) $(BUILDDIR)/text + @echo + @echo "Build finished. The text files are in $(BUILDDIR)/text." + +man: $(IMAGES) + $(SPHINXBUILD) -b man $(ALLSPHINXOPTS) $(BUILDDIR)/man + @echo + @echo "Build finished. The manual pages are in $(BUILDDIR)/man." + +changes: $(IMAGES) + $(SPHINXBUILD) -b changes $(ALLSPHINXOPTS) $(BUILDDIR)/changes + @echo + @echo "The overview file is in $(BUILDDIR)/changes." + +linkcheck: $(IMAGEs) + $(SPHINXBUILD) -b linkcheck $(ALLSPHINXOPTS) $(BUILDDIR)/linkcheck + @echo + @echo "Link check complete; look for any errors in the above output " \ + "or in $(BUILDDIR)/linkcheck/output.txt." + +doctest: $(IMAGES) + $(SPHINXBUILD) -b doctest $(ALLSPHINXOPTS) $(BUILDDIR)/doctest + @echo "Testing of doctests in the sources finished, look at the " \ + "results in $(BUILDDIR)/doctest/output.txt." diff --git a/doc/tutorial/conceptual-overview.texi b/doc/tutorial/conceptual-overview.texi deleted file mode 100644 index 67ebeb5b5..000000000 --- a/doc/tutorial/conceptual-overview.texi +++ /dev/null @@ -1,847 +0,0 @@ - -@c ======================================================================== -@c Begin document body here -@c ======================================================================== - -@c ======================================================================== -@c Conceptual Overview -@c ======================================================================== -@node Conceptual Overview -@chapter Conceptual Overview - -@menu -* Key Abstractions:: -* A First ns-3 Script:: -@end menu - -The first thing we need to do before actually starting to look at or write -@command{ns-3} code is to explain a few core concepts and abstractions in the -system. Much of this may appear transparently obvious to some, but we -recommend taking the time to read through this section just to ensure you -are starting on a firm foundation. - -@node Key Abstractions -@section Key Abstractions - -In this section, we'll review some terms that are commonly used in -networking, but have a specific meaning in @command{ns-3}. - -@subsection Node -@cindex Node -In Internet jargon, a computing device that connects to a network is called -a @emph{host} or sometimes an @emph{end system}. Because @command{ns-3} is a -@emph{network} simulator, not specifically an @emph{Internet} simulator, we -intentionally do not use the term host since it is closely associated with -the Internet and its protocols. Instead, we use a more generic term also -used by other simulators that originates in Graph Theory --- the @emph{node}. - -@cindex class Node -In @command{ns-3} the basic computing device abstraction is called the -node. This abstraction is represented in C++ by the class @code{Node}. The -@code{Node} class provides methods for managing the representations of -computing devices in simulations. - -You should think of a @code{Node} as a computer to which you will add -functionality. One adds things like applications, protocol stacks and -peripheral cards with their associated drivers to enable the computer to do -useful work. We use the same basic model in @command{ns-3}. - -@subsection Application -@cindex Application -Typically, computer software is divided into two broad classes. @emph{System -Software} organizes various computer resources such as memory, processor -cycles, disk, network, etc., according to some computing model. System -software usually does not use those resources to complete tasks that directly -benefit a user. A user would typically run an @emph{application} that acquires -and uses the resources controlled by the system software to accomplish some -goal. - -@cindex system call -Often, the line of separation between system and application software is made -at the privilege level change that happens in operating system traps. -In @command{ns-3} there is no real concept of operating system and especially -no concept of privilege levels or system calls. We do, however, have the -idea of an application. Just as software applications run on computers to -perform tasks in the ``real world,'' @command{ns-3} applications run on -@command{ns-3} @code{Nodes} to drive simulations in the simulated world. - -@cindex class Application -In @command{ns-3} the basic abstraction for a user program that generates some -activity to be simulated is the application. This abstraction is represented -in C++ by the class @code{Application}. The @code{Application} class provides -methods for managing the representations of our version of user-level -applications in simulations. Developers are expected to specialize the -@code{Application} class in the object-oriented programming sense to create new -applications. In this tutorial, we will use specializations of class -@code{Application} called @code{UdpEchoClientApplication} and -@code{UdpEchoServerApplication}. As you might expect, these applications -compose a client/server application set used to generate and echo simulated -network packets - -@subsection Channel -@cindex Channel - -In the real world, one can connect a computer to a network. Often the media -over which data flows in these networks are called @emph{channels}. When -you connect your Ethernet cable to the plug in the wall, you are connecting -your computer to an Ethernet communication channel. In the simulated world -of @command{ns-3}, one connects a @code{Node} to an object representing a -communication channel. Here the basic communication subnetwork abstraction -is called the channel and is represented in C++ by the class @code{Channel}. - -The @code{Channel} class provides methods for managing communication -subnetwork objects and connecting nodes to them. @code{Channels} may also be -specialized by developers in the object oriented programming sense. A -@code{Channel} specialization may model something as simple as a wire. The -specialized @code{Channel} can also model things as complicated as a large -Ethernet switch, or three-dimensional space full of obstructions in the case -of wireless networks. - -We will use specialized versions of the @code{Channel} called -@code{CsmaChannel}, @code{PointToPointChannel} and @code{WifiChannel} in this -tutorial. The @code{CsmaChannel}, for example, models a version of a -communication subnetwork that implements a @emph{carrier sense multiple -access} communication medium. This gives us Ethernet-like functionality. - -@subsection Net Device -@cindex NetDevice -@cindex Ethernet -It used to be the case that if you wanted to connect a computers to a network, -you had to buy a specific kind of network cable and a hardware device called -(in PC terminology) a @emph{peripheral card} that needed to be installed in -your computer. If the peripheral card implemented some networking function, -they were called Network Interface Cards, or @emph{NICs}. Today most -computers come with the network interface hardware built in and users don't -see these building blocks. - -A NIC will not work without a software driver to control the hardware. In -Unix (or Linux), a piece of peripheral hardware is classified as a -@emph{device}. Devices are controlled using @emph{device drivers}, and network -devices (NICs) are controlled using @emph{network device drivers} -collectively known as @emph{net devices}. In Unix and Linux you refer -to these net devices by names such as @emph{eth0}. - -In @command{ns-3} the @emph{net device} abstraction covers both the software -driver and the simulated hardware. A net device is ``installed'' in a -@code{Node} in order to enable the @code{Node} to communicate with other -@code{Nodes} in the simulation via @code{Channels}. Just as in a real -computer, a @code{Node} may be connected to more than one @code{Channel} via -multiple @code{NetDevices}. - -The net device abstraction is represented in C++ by the class @code{NetDevice}. -The @code{NetDevice} class provides methods for managing connections to -@code{Node} and @code{Channel} objects; and may be specialized by developers -in the object-oriented programming sense. We will use the several specialized -versions of the @code{NetDevice} called @code{CsmaNetDevice}, -@code{PointToPointNetDevice}, and @code{WifiNetDevice} in this tutorial. -Just as an Ethernet NIC is designed to work with an Ethernet network, the -@code{CsmaNetDevice} is designed to work with a @code{CsmaChannel}; the -@code{PointToPointNetDevice} is designed to work with a -@code{PointToPointChannel} and a @code{WifiNetNevice} is designed to work with -a @code{WifiChannel}. - -@subsection Topology Helpers -@cindex helper -@cindex topology -@cindex topology helper -In a real network, you will find host computers with added (or built-in) -NICs. In @command{ns-3} we would say that you will find @code{Nodes} with -attached @code{NetDevices}. In a large simulated network you will need to -arrange many connections between @code{Nodes}, @code{NetDevices} and -@code{Channels}. - -Since connecting @code{NetDevices} to @code{Nodes}, @code{NetDevices} -to @code{Channels}, assigning IP addresses, etc., are such common tasks -in @command{ns-3}, we provide what we call @emph{topology helpers} to make -this as easy as possible. For example, it may take many distinct -@command{ns-3} core operations to create a NetDevice, add a MAC address, -install that net device on a @code{Node}, configure the node's protocol stack, -and then connect the @code{NetDevice} to a @code{Channel}. Even more -operations would be required to connect multiple devices onto multipoint -channels and then to connect individual networks together into internetworks. -We provide topology helper objects that combine those many distinct operations -into an easy to use model for your convenience. - -@c ======================================================================== -@c A First ns-3 script -@c ======================================================================== -@node A First ns-3 Script -@section A First ns-3 Script -@cindex first script -If you downloaded the system as was suggested above, you will have a release -of @command{ns-3} in a directory called @code{repos} under your home -directory. Change into that release directory, and you should find a -directory structure something like the following: - -@verbatim - AUTHORS doc/ README src/ waf.bat* - bindings/ examples/ RELEASE_NOTES utils/ wscript - build/ LICENSE samples/ VERSION wutils.py - CHANGES.html ns3/ scratch/ waf* wutils.pyc -@end verbatim - -@cindex first.cc -Change into the @code{examples/tutorial} directory. You should see a file named -@code{first.cc} located there. This is a script that will create a simple -point-to-point link between two nodes and echo a single packet between the -nodes. Let's take a look at that script line by line, so go ahead and open -@code{first.cc} in your favorite editor. - -@subsection Boilerplate -The first line in the file is an emacs mode line. This tells emacs about the -formatting conventions (coding style) we use in our source code. - -@verbatim - /* -*- Mode:C++; c-file-style:''gnu''; indent-tabs-mode:nil; -*- */ -@end verbatim - -This is always a somewhat controversial subject, so we might as well get it -out of the way immediately. The @code{ns-3} project, like most large -projects, has adopted a coding style to which all contributed code must -adhere. If you want to contribute your code to the project, you will -eventually have to conform to the @command{ns-3} coding standard as described -in the file @code{doc/codingstd.txt} or shown on the project web page -@uref{http://www.nsnam.org/codingstyle.html,,here}. - -We recommend that you, well, just get used to the look and feel of @code{ns-3} -code and adopt this standard whenever you are working with our code. All of -the development team and contributors have done so with various amounts of -grumbling. The emacs mode line above makes it easier to get the formatting -correct if you use the emacs editor. - -The @command{ns-3} simulator is licensed using the GNU General Public -License. You will see the appropriate GNU legalese at the head of every file -in the @command{ns-3} distribution. Often you will see a copyright notice for -one of the institutions involved in the @code{ns-3} project above the GPL -text and an author listed below. - -@verbatim - /* - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License version 2 as - * published by the Free Software Foundation; - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA - */ -@end verbatim - -@subsection Module Includes -The code proper starts with a number of include statements. - -@verbatim - #include "ns3/core-module.h" - #include "ns3/simulator-module.h" - #include "ns3/node-module.h" - #include "ns3/helper-module.h" -@end verbatim - -To help our high-level script users deal with the large number of include -files present in the system, we group includes according to relatively large -modules. We provide a single include file that will recursively load all of -the include files used in each module. Rather than having to look up exactly -what header you need, and possibly have to get a number of dependencies right, -we give you the ability to load a group of files at a large granularity. This -is not the most efficient approach but it certainly makes writing scripts much -easier. - -Each of the @command{ns-3} include files is placed in a directory called -@code{ns3} (under the build directory) during the build process to help avoid -include file name collisions. The @code{ns3/core-module.h} file corresponds -to the ns-3 module you will find in the directory @code{src/core} in your -downloaded release distribution. If you list this directory you will find a -large number of header files. When you do a build, Waf will place public -header files in an @code{ns3} directory under the appropriate -@code{build/debug} or @code{build/optimized} directory depending on your -configuration. Waf will also automatically generate a module include file to -load all of the public header files. - -Since you are, of course, following this tutorial religiously, you will -already have done a - -@verbatim - ./waf -d debug configure -@end verbatim - -in order to configure the project to perform debug builds. You will also have -done a - -@verbatim - ./waf -@end verbatim - -to build the project. So now if you look in the directory -@code{../../build/debug/ns3} you will find the four module include files shown -above. You can take a look at the contents of these files and find that they -do include all of the public include files in their respective modules. - -@subsection Ns3 Namespace -The next line in the @code{first.cc} script is a namespace declaration. - -@verbatim - using namespace ns3; -@end verbatim - -The @command{ns-3} project is implemented in a C++ namespace called -@code{ns3}. This groups all @command{ns-3}-related declarations in a scope -outside the global namespace, which we hope will help with integration with -other code. The C++ @code{using} statement introduces the @code{ns-3} -namespace into the current (global) declarative region. This is a fancy way -of saying that after this declaration, you will not have to type @code{ns3::} -scope resolution operator before all of the @code{ns-3} code in order to use -it. If you are unfamiliar with namespaces, please consult almost any C++ -tutorial and compare the @code{ns3} namespace and usage here with instances of -the @code{std} namespace and the @code{using namespace std;} statements you -will often find in discussions of @code{cout} and streams. - -@subsection Logging -The next line of the script is the following, - -@verbatim - NS_LOG_COMPONENT_DEFINE ("FirstScriptExample"); -@end verbatim - -We will use this statement as a convenient place to talk about our Doxygen -documentation system. If you look at the project web site, -@uref{http://www.nsnam.org,,ns-3 project}, you will find a link to ``Doxygen -(ns-3-dev)'' in the navigation bar. If you select this link, you will be -taken to our documentation page for the current development release. There -is also a link to ``Doxygen (stable)'' that will take you to the documentation -for the latest stable release of @code{ns-3}. - -Along the left side, you will find a graphical representation of the structure -of the documentation. A good place to start is the @code{NS-3 Modules} -``book'' in the @code{ns-3} navigation tree. If you expand @code{Modules} -you will see a list of @command{ns-3} module documentation. The concept of -module here ties directly into the module include files discussed above. It -turns out that the @command{ns-3} logging subsystem is part of the @code{core} -module, so go ahead and expand that documentation node. Now, expand the -@code{Debugging} book and then select the @code{Logging} page. - -You should now be looking at the Doxygen documentation for the Logging module. -In the list of @code{#define}s at the top of the page you will see the entry -for @code{NS_LOG_COMPONENT_DEFINE}. Before jumping in, it would probably be -good to look for the ``Detailed Description'' of the logging module to get a -feel for the overall operation. You can either scroll down or select the -``More...'' link under the collaboration diagram to do this. - -Once you have a general idea of what is going on, go ahead and take a look at -the specific @code{NS_LOG_COMPONENT_DEFINE} documentation. I won't duplicate -the documentation here, but to summarize, this line declares a logging -component called @code{FirstScriptExample} that allows you to enable and -disable console message logging by reference to the name. - -@subsection Main Function -The next lines of the script you will find are, - -@verbatim - int - main (int argc, char *argv[]) - { -@end verbatim - -This is just the declaration of the main function of your program (script). -Just as in any C++ program, you need to define a main function that will be -the first function run. There is nothing at all special here. Your -@command{ns-3} script is just a C++ program. - -The next two lines of the script are used to enable two logging components that -are built into the Echo Client and Echo Server applications: - -@verbatim - LogComponentEnable("UdpEchoClientApplication", LOG_LEVEL_INFO); - LogComponentEnable("UdpEchoServerApplication", LOG_LEVEL_INFO); -@end verbatim - -If you have read over the Logging component documentation you will have seen -that there are a number of levels of logging verbosity/detail that you can -enable on each component. These two lines of code enable debug logging at the -INFO level for echo clients and servers. This will result in the application -printing out messages as packets are sent and received during the simulation. - -Now we will get directly to the business of creating a topology and running -a simulation. We use the topology helper objects to make this job as -easy as possible. - -@subsection Topology Helpers -@subsubsection NodeContainer -The next two lines of code in our script will actually create the -@command{ns-3} @code{Node} objects that will represent the computers in the -simulation. - -@verbatim - NodeContainer nodes; - nodes.Create (2); -@end verbatim - -Let's find the documentation for the @code{NodeContainer} class before we -continue. Another way to get into the documentation for a given class is via -the @code{Classes} tab in the Doxygen pages. If you still have the Doxygen -handy, just scroll up to the top of the page and select the @code{Classes} -tab. You should see a new set of tabs appear, one of which is -@code{Class List}. Under that tab you will see a list of all of the -@command{ns-3} classes. Scroll down, looking for @code{ns3::NodeContainer}. -When you find the class, go ahead and select it to go to the documentation for -the class. - -You may recall that one of our key abstractions is the @code{Node}. This -represents a computer to which we are going to add things like protocol stacks, -applications and peripheral cards. The @code{NodeContainer} topology helper -provides a convenient way to create, manage and access any @code{Node} objects -that we create in order to run a simulation. The first line above just -declares a NodeContainer which we call @code{nodes}. The second line calls the -@code{Create} method on the @code{nodes} object and asks the container to -create two nodes. As described in the Doxygen, the container calls down into -the @command{ns-3} system proper to create two @code{Node} objects and stores -pointers to those objects internally. - -The nodes as they stand in the script do nothing. The next step in -constructing a topology is to connect our nodes together into a network. -The simplest form of network we support is a single point-to-point link -between two nodes. We'll construct one of those links here. - -@subsubsection PointToPointHelper -We are constructing a point to point link, and, in a pattern which will become -quite familiar to you, we use a topology helper object to do the low-level -work required to put the link together. Recall that two of our key -abstractions are the @code{NetDevice} and the @code{Channel}. In the real -world, these terms correspond roughly to peripheral cards and network cables. -Typically these two things are intimately tied together and one cannot expect -to interchange, for example, Ethernet devices and wireless channels. Our -Topology Helpers follow this intimate coupling and therefore you will use a -single @code{PointToPointHelper} to configure and connect @command{ns-3} -@code{PointToPointNetDevice} and @code{PointToPointChannel} objects in this -script. - -The next three lines in the script are, - -@verbatim - PointToPointHelper pointToPoint; - pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("5Mbps")); - pointToPoint.SetChannelAttribute ("Delay", StringValue ("2ms")); -@end verbatim - -The first line, - -@verbatim - PointToPointHelper pointToPoint; -@end verbatim - -instantiates a @code{PointToPointHelper} object on the stack. From a -high-level perspective the next line, - -@verbatim - pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("5Mbps")); -@end verbatim - -tells the @code{PointToPointHelper} object to use the value ``5Mbps'' -(five megabits per second) as the ``DataRate'' when it creates a -@code{PointToPointNetDevice} object. - -From a more detailed perspective, the string ``DataRate'' corresponds -to what we call an @code{Attribute} of the @code{PointToPointNetDevice}. -If you look at the Doxygen for class @code{ns3::PointToPointNetDevice} and -find the documentation for the @code{GetTypeId} method, you will find a list -of @code{Attributes} defined for the device. Among these is the ``DataRate'' -@code{Attribute}. Most user-visible @command{ns-3} objects have similar lists of -@code{Attributes}. We use this mechanism to easily configure simulations without -recompiling as you will see in a following section. - -Similar to the ``DataRate'' on the @code{PointToPointNetDevice} you will find a -``Delay'' @code{Attribute} associated with the @code{PointToPointChannel}. The -final line, - -@verbatim - pointToPoint.SetChannelAttribute ("Delay", StringValue ("2ms")); -@end verbatim - -tells the @code{PointToPointHelper} to use the value ``2ms'' (two milliseconds) -as the value of the transmission delay of every point to point channel it -subsequently creates. - -@subsubsection NetDeviceContainer -At this point in the script, we have a @code{NodeContainer} that contains -two nodes. We have a @code{PointToPointHelper} that is primed and ready to -make @code{PointToPointNetDevices} and wire @code{PointToPointChannel} objects -between them. Just as we used the @code{NodeContainer} topology helper object -to create the @code{Nodes} for our simulation, we will ask the -@code{PointToPointHelper} to do the work involved in creating, configuring and -installing our devices for us. We will need to have a list of all of the -NetDevice objects that are created, so we use a NetDeviceContainer to hold -them just as we used a NodeContainer to hold the nodes we created. The -following two lines of code, - -@verbatim - NetDeviceContainer devices; - devices = pointToPoint.Install (nodes); -@end verbatim - -will finish configuring the devices and channel. The first line declares the -device container mentioned above and the second does the heavy lifting. The -@code{Install} method of the @code{PointToPointHelper} takes a -@code{NodeContainer} as a parameter. Internally, a @code{NetDeviceContainer} -is created. For each node in the @code{NodeContainer} (there must be exactly -two for a point-to-point link) a @code{PointToPointNetDevice} is created and -saved in the device container. A @code{PointToPointChannel} is created and -the two @code{PointToPointNetDevices} are attached. When objects are created -by the @code{PointToPointHelper}, the @code{Attributes} previously set in the -helper are used to initialize the corresponding @code{Attributes} in the -created objects. - -After executing the @code{pointToPoint.Install (nodes)} call we will have -two nodes, each with an installed point-to-point net device and a single -point-to-point channel between them. Both devices will be configured to -transmit data at five megabits per second over the channel which has a two -millisecond transmission delay. - -@subsubsection InternetStackHelper -We now have nodes and devices configured, but we don't have any protocol stacks -installed on our nodes. The next two lines of code will take care of that. - -@verbatim - InternetStackHelper stack; - stack.Install (nodes); -@end verbatim - -The @code{InternetStackHelper} is a topology helper that is to internet stacks -what the @code{PointToPointHelper} is to point-to-point net devices. The -@code{Install} method takes a @code{NodeContainer} as a parameter. When it is -executed, it will install an Internet Stack (TCP, UDP, IP, etc.) on each of -the nodes in the node container. - -@subsubsection Ipv4AddressHelper -Next we need to associate the devices on our nodes with IP addresses. We -provide a topology helper to manage the allocation of IP addresses. The only -user-visible API is to set the base IP address and network mask to use when -performing the actual address allocation (which is done at a lower level -inside the helper). - -The next two lines of code in our example script, @code{first.cc}, - -@verbatim - Ipv4AddressHelper address; - address.SetBase ("10.1.1.0", "255.255.255.0"); -@end verbatim - -declare an address helper object and tell it that it should begin allocating IP -addresses from the network 10.1.1.0 using the mask 255.255.255.0 to define -the allocatable bits. By default the addresses allocated will start at one -and increase monotonically, so the first address allocated from this base will -be 10.1.1.1, followed by 10.1.1.2, etc. The low level @command{ns-3} system -actually remembers all of the IP addresses allocated and will generate a -fatal error if you accidentally cause the same address to be generated twice -(which is a very hard to debug error, by the way). - -The next line of code, - -@verbatim - Ipv4InterfaceContainer interfaces = address.Assign (devices); -@end verbatim - -performs the actual address assignment. In @command{ns-3} we make the -association between an IP address and a device using an @code{Ipv4Interface} -object. Just as we sometimes need a list of net devices created by a helper -for future reference we sometimes need a list of @code{Ipv4Interface} objects. -The @code{Ipv4InterfaceContainer} provides this functionality. - -Now we have a point-to-point network built, with stacks installed and IP -addresses assigned. What we need at this point are applications to generate -traffic. - -@subsection Applications -Another one of the core abstractions of the ns-3 system is the -@code{Application}. In this script we use two specializations of the core -@command{ns-3} class @code{Application} called @code{UdpEchoServerApplication} -and @code{UdpEchoClientApplication}. Just as we have in our previous -explanations, we use helper objects to help configure and manage the -underlying objects. Here, we use @code{UdpEchoServerHelper} and -@code{UdpEchoClientHelper} objects to make our lives easier. - -@subsubsection UdpEchoServerHelper -The following lines of code in our example script, @code{first.cc}, are used -to set up a UDP echo server application on one of the nodes we have previously -created. - -@verbatim - UdpEchoServerHelper echoServer (9); - - ApplicationContainer serverApps = echoServer.Install (nodes.Get (1)); - serverApps.Start (Seconds (1.0)); - serverApps.Stop (Seconds (10.0)); -@end verbatim - -The first line of code in the above snippet declares the -@code{UdpEchoServerHelper}. As usual, this isn't the application itself, it -is an object used to help us create the actual applications. One of our -conventions is to place @emph{required} @code{Attributes} in the helper constructor. -In this case, the helper can't do anything useful unless it is provided with -a port number that the client also knows about. Rather than just picking one -and hoping it all works out, we require the port number as a parameter to the -constructor. The constructor, in turn, simply does a @code{SetAttribute} -with the passed value. If you want, you can set the ``Port'' @code{Attribute} -to another value later using @code{SetAttribute}. - -Similar to many other helper objects, the @code{UdpEchoServerHelper} object -has an @code{Install} method. It is the execution of this method that actually -causes the underlying echo server application to be instantiated and attached -to a node. Interestingly, the @code{Install} method takes a -@code{NodeContainter} as a parameter just as the other @code{Install} methods -we have seen. This is actually what is passed to the method even though it -doesn't look so in this case. There is a C++ @emph{implicit conversion} at -work here that takes the result of @code{nodes.Get (1)} (which returns a smart -pointer to a node object --- @code{Ptr}) and uses that in a constructor -for an unnamed @code{NodeContainer} that is then passed to @code{Install}. -If you are ever at a loss to find a particular method signature in C++ code -that compiles and runs just fine, look for these kinds of implicit conversions. - -We now see that @code{echoServer.Install} is going to install a -@code{UdpEchoServerApplication} on the node found at index number one of the -@code{NodeContainer} we used to manage our nodes. @code{Install} will return -a container that holds pointers to all of the applications (one in this case -since we passed a @code{NodeContainer} containing one node) created by the -helper. - -Applications require a time to ``start'' generating traffic and may take an -optional time to ``stop''. We provide both. These times are set using the -@code{ApplicationContainer} methods @code{Start} and @code{Stop}. These -methods take @code{Time} parameters. In this case, we use an @emph{explicit} -C++ conversion sequence to take the C++ double 1.0 and convert it to an -@command{ns-3} @code{Time} object using a @code{Seconds} cast. Be aware that -the conversion rules may be controlled by the model author, and C++ has its -own rules, so you can't always just assume that parameters will be happily -converted for you. The two lines, - -@verbatim - serverApps.Start (Seconds (1.0)); - serverApps.Stop (Seconds (10.0)); -@end verbatim - -will cause the echo server application to @code{Start} (enable itself) at one -second into the simulation and to @code{Stop} (disable itself) at ten seconds -into the simulation. By virtue of the fact that we have declared a simulation -event (the application stop event) to be executed at ten seconds, the simulation -will last @emph{at least} ten seconds. - -@subsubsection UdpEchoClientHelper - -The echo client application is set up in a method substantially similar to -that for the server. There is an underlying @code{UdpEchoClientApplication} -that is managed by an @code{UdpEchoClientHelper}. - -@verbatim - UdpEchoClientHelper echoClient (interfaces.GetAddress (1), 9); - echoClient.SetAttribute ("MaxPackets", UintegerValue (1)); - echoClient.SetAttribute ("Interval", TimeValue (Seconds (1.))); - echoClient.SetAttribute ("PacketSize", UintegerValue (1024)); - - ApplicationContainer clientApps = echoClient.Install (nodes.Get (0)); - clientApps.Start (Seconds (2.0)); - clientApps.Stop (Seconds (10.0)); -@end verbatim - -For the echo client, however, we need to set five different @code{Attributes}. -The first two @code{Attributes} are set during construction of the -@code{UdpEchoClientHelper}. We pass parameters that are used (internally to -the helper) to set the ``RemoteAddress'' and ``RemotePort'' @code{Attributes} -in accordance with our convention to make required @code{Attributes} parameters -in the helper constructors. - -Recall that we used an @code{Ipv4InterfaceContainer} to keep track of the IP -addresses we assigned to our devices. The zeroth interface in the -@code{interfaces} container is going to correspond to the IP address of the -zeroth node in the @code{nodes} container. The first interface in the -@code{interfaces} container corresponds to the IP address of the first node -in the @code{nodes} container. So, in the first line of code (from above), we -are creating the helper and telling it so set the remote address of the client -to be the IP address assigned to the node on which the server resides. We -also tell it to arrange to send packets to port nine. - -The ``MaxPackets'' @code{Attribute} tells the client the maximum number of -packets we allow it to send during the simulation. The ``Interval'' -@code{Attribute} tells the client how long to wait between packets, and the -``PacketSize'' @code{Attribute} tells the client how large its packet payloads -should be. With this particular combination of @code{Attributes}, we are -telling the client to send one 1024-byte packet. - -Just as in the case of the echo server, we tell the echo client to @code{Start} -and @code{Stop}, but here we start the client one second after the server is -enabled (at two seconds into the simulation). - -@subsection Simulator -What we need to do at this point is to actually run the simulation. This is -done using the global function @code{Simulator::Run}. - -@verbatim - Simulator::Run (); -@end verbatim - -When we previously called the methods, - -@verbatim - serverApps.Start (Seconds (1.0)); - serverApps.Stop (Seconds (10.0)); - ... - clientApps.Start (Seconds (2.0)); - clientApps.Stop (Seconds (10.0)); -@end verbatim - -we actually scheduled events in the simulator at 1.0 seconds, 2.0 seconds and -two events at 10.0 seconds. When @code{Simulator::Run} is called, the system -will begin looking through the list of scheduled events and executing them. -First it will run the event at 1.0 seconds, which will enable the echo server -application (this event may, in turn, schedule many other events). Then it -will run the event scheduled for t=2.0 seconds which will start the echo client -application. Again, this event may schedule many more events. The start event -implementation in the echo client application will begin the data transfer phase -of the simulation by sending a packet to the server. - -The act of sending the packet to the server will trigger a chain of events -that will be automatically scheduled behind the scenes and which will perform -the mechanics of the packet echo according to the various timing parameters -that we have set in the script. - -Eventually, since we only send one packet (recall the @code{MaxPackets} -@code{Attribute} was set to one), the chain of events triggered by -that single client echo request will taper off and the simulation will go -idle. Once this happens, the remaining events will be the @code{Stop} events -for the server and the client. When these events are executed, there are -no further events to process and @code{Simulator::Run} returns. The simulation -is then complete. - -All that remains is to clean up. This is done by calling the global function -@code{Simulator::Destroy}. As the helper functions (or low level -@command{ns-3} code) executed, they arranged it so that hooks were inserted in -the simulator to destroy all of the objects that were created. You did not -have to keep track of any of these objects yourself --- all you had to do -was to call @code{Simulator::Destroy} and exit. The @command{ns-3} system -took care of the hard part for you. The remaining lines of our first -@command{ns-3} script, @code{first.cc}, do just that: - -@verbatim - Simulator::Destroy (); - return 0; - } -@end verbatim - -@subsection Building Your Script -We have made it trivial to build your simple scripts. All you have to do is -to drop your script into the scratch directory and it will automatically be -built if you run Waf. Let's try it. Copy @code{examples/tutorial/first.cc} into -the @code{scratch} directory after changing back into the top level directory. - -@verbatim - cd .. - cp examples/tutorial/first.cc scratch/myfirst.cc -@end verbatim - -Now build your first example script using waf: - -@verbatim - ./waf -@end verbatim - -You should see messages reporting that your @code{myfirst} example was built -successfully. - -@verbatim - Waf: Entering directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' - [614/708] cxx: scratch/myfirst.cc -> build/debug/scratch/myfirst_3.o - [706/708] cxx_link: build/debug/scratch/myfirst_3.o -> build/debug/scratch/myfirst - Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' - 'build' finished successfully (2.357s) -@end verbatim - -You can now run the example (note that if you build your program in the scratch -directory you must run it out of the scratch directory): - -@verbatim - ./waf --run scratch/myfirst -@end verbatim - -You should see some output: - -@verbatim - Waf: Entering directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' - Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' - 'build' finished successfully (0.418s) - Sent 1024 bytes to 10.1.1.2 - Received 1024 bytes from 10.1.1.1 - Received 1024 bytes from 10.1.1.2 -@end verbatim - -Here you see that the build system checks to make sure that the file has been -build and then runs it. You see the logging component on the echo client -indicate that it has sent one 1024 byte packet to the Echo Server on -10.1.1.2. You also see the logging component on the echo server say that -it has received the 1024 bytes from 10.1.1.1. The echo server silently -echoes the packet and you see the echo client log that it has received its -packet back from the server. - -@c ======================================================================== -@c Browsing ns-3 -@c ======================================================================== - -@node Ns-3 Source Code -@section Ns-3 Source Code - -Now that you have used some of the @command{ns-3} helpers you may want to -have a look at some of the source code that implements that functionality. -The most recent code can be browsed on our web server at the following link: -@uref{http://code.nsnam.org/ns-3-dev}. There, you will see the Mercurial -summary page for our @command{ns-3} development tree. - -At the top of the page, you will see a number of links, - -@verbatim - summary | shortlog | changelog | graph | tags | files -@end verbatim - -Go ahead and select the @code{files} link. This is what the top-level of -most of our @emph{repositories} will look: - -@verbatim -drwxr-xr-x [up] -drwxr-xr-x bindings python files -drwxr-xr-x doc files -drwxr-xr-x examples files -drwxr-xr-x ns3 files -drwxr-xr-x samples files -drwxr-xr-x scratch files -drwxr-xr-x src files -drwxr-xr-x utils files --rw-r--r-- 2009-07-01 12:47 +0200 560 .hgignore file | revisions | annotate --rw-r--r-- 2009-07-01 12:47 +0200 1886 .hgtags file | revisions | annotate --rw-r--r-- 2009-07-01 12:47 +0200 1276 AUTHORS file | revisions | annotate --rw-r--r-- 2009-07-01 12:47 +0200 30961 CHANGES.html file | revisions | annotate --rw-r--r-- 2009-07-01 12:47 +0200 17987 LICENSE file | revisions | annotate --rw-r--r-- 2009-07-01 12:47 +0200 3742 README file | revisions | annotate --rw-r--r-- 2009-07-01 12:47 +0200 16171 RELEASE_NOTES file | revisions | annotate --rw-r--r-- 2009-07-01 12:47 +0200 6 VERSION file | revisions | annotate --rwxr-xr-x 2009-07-01 12:47 +0200 88110 waf file | revisions | annotate --rwxr-xr-x 2009-07-01 12:47 +0200 28 waf.bat file | revisions | annotate --rw-r--r-- 2009-07-01 12:47 +0200 35395 wscript file | revisions | annotate --rw-r--r-- 2009-07-01 12:47 +0200 7673 wutils.py file | revisions | annotate -@end verbatim - -Our example scripts are in the @code{examples} directory. If you click on @code{examples} -you will see a list of files. One of the files in that directory is @code{first.cc}. If -you click on @code{first.cc} you will find the code you just walked through. - -The source code is mainly in the @code{src} directory. You can view source -code either by clicking on the directory name or by clicking on the @code{files} -link to the right of the directory name. If you click on the @code{src} -directory, you will be taken to the listing of the @code{src} subdirectories. If you -then click on @code{core} subdirectory, you will find a list of files. The first file -you will find (as of this writing) is @code{abort.h}. If you click on the -@code{abort.h} link, you will be sent to the source file for @code{abort.h} which -contains useful macros for exiting scripts if abnormal conditions are detected. - -The source code for the helpers we have used in this chapter can be found in the -@code{src/helper} directory. Feel free to poke around in the directory tree to -get a feel for what is there and the style of @command{ns-3} programs. diff --git a/doc/tutorial/conclusion.texi b/doc/tutorial/conclusion.texi deleted file mode 100644 index e0a67b9a7..000000000 --- a/doc/tutorial/conclusion.texi +++ /dev/null @@ -1,60 +0,0 @@ -@c ============================================================================ -@c Begin document body here -@c ============================================================================ - -@c ============================================================================ -@c PART: Closing Remarks -@c ============================================================================ -@c The below chapters are under the major heading "Closing Remarks" -@c This is similar to the Latex \part command -@c -@c ============================================================================ -@c Closing Remarks -@c ============================================================================ -@node Closing Remarks -@chapter Closing Remarks - -@menu -* Futures:: -* Closing:: -@end menu - -@c ============================================================================ -@c Futures -@c ============================================================================ -@node -@section Futures - -This document is a work in process. We hope and expect it to grow over time -to cover more and more of the nuts and bolts of @command{ns-3}. - -We hope to add the following chapters over the next few releases: - -@itemize @bullet -@item The Callback System -@item The Object System and Memory Management -@item The Routing System -@item Adding a New NetDevice and Channel -@item Adding a New Protocol -@item Working with Real Networks and Hosts -@end itemize - -Writing manual and tutorial chapters is not something we all get excited about, -but it is very important to the project. If you are an expert in one of these -areas, please consider contributing to @command{ns-3} by providing one of these -chapters; or any other chapter you may think is important. - -@c ============================================================================ -@c Closing -@c ============================================================================ -@node -@section Closing - -@code{ns-3} is a large and complicated system. It is impossible to cover all -of the things you will need to know in one small tutorial. - -We have really just scratched the surface of @command{ns-3} in this tutorial, -but we hope to have covered enough to get you started doing useful networking -research using our favorite simulator. - --- The @command{ns-3} development team. diff --git a/doc/tutorial/in-process/Makefile b/doc/tutorial/in-process/Makefile deleted file mode 100644 index 58857b0dd..000000000 --- a/doc/tutorial/in-process/Makefile +++ /dev/null @@ -1,49 +0,0 @@ -TEXI2HTML = texi2html -TEXI2PDF = texi2dvi --pdf -EPSTOPDF = epstopdf -TGIF = tgif -DIA = dia -CONVERT = convert -CSS = --css-include=tutorial.css -SPLIT = --split section - -DIA_SOURCES = pp.dia dumbbell.dia star.dia -TGIF_SOURCES = helpers.obj - -DIA_EPS = ${DIA_SOURCES:.dia=.eps} -DIA_PNG = ${DIA_SOURCES:.dia=.png} -DIA_PDF = ${DIA_SOURCES:.dia=.pdf} - -TGIF_EPS = ${TGIF_SOURCES:.obj=.eps} -TGIF_PNG = ${TGIF_SOURCES:.obj=.png} -TGIF_PDF = ${TGIF_SOURCES:.obj=.pdf} - -all: images html split-html pdf - -# Note: tgif requires a valid x display to convert from .obj to .png. -# If running this makefile on a remote console, the X virtual frame -# buffer may be needed (xorg-x11-server-Xvfb) to provide a "fake" -# display -images: - cd figures/; $(DIA) -t png $(DIA_SOURCES) - cd figures/; $(DIA) -t eps $(DIA_SOURCES) - cd figures/; $(foreach FILE,$(DIA_EPS),$(EPSTOPDF) $(FILE);) - cd figures/; $(TGIF) -print -png $(TGIF_SOURCES) - cd figures/; $(TGIF) -print -eps $(TGIF_SOURCES) - cd figures/; $(foreach FILE,$(TGIF_EPS),$(EPSTOPDF) $(FILE);) - -html: images - $(TEXI2HTML) ${CSS} tutorial.texi - -split-html: images - $(TEXI2HTML) ${CSS} ${SPLIT} tutorial.texi - -pdf: images - $(TEXI2PDF) tutorial.texi - -figures-clean: - cd figures/; rm -rf $(DIA_EPS); rm -rf $(DIA_PNG); rm -rf $(DIA_PDF) - cd figures/; rm -rf $(TGIF_EPS); rm -rf $(TGIF_PNG); rm -rf $(TGIF_PDF) - -clean: figures-clean - rm -rf tutorial.aux tutorial.cp tutorial.cps tutorial.fn tutorial.ky tutorial.pg tutorial.tp tutorial.vr tutorial.toc tutorial.log tutorial.pdf tutorial.html tutorial/ diff --git a/doc/tutorial/in-process/attributes.texi b/doc/tutorial/in-process/attributes.texi deleted file mode 100644 index 192d6a8fe..000000000 --- a/doc/tutorial/in-process/attributes.texi +++ /dev/null @@ -1,535 +0,0 @@ -@node ns-3 Attributes -@chapter ns-3 Attributes -@anchor{chap:Attributes} - -In ns-3 simulations, there are two main aspects to configuration: -@itemize @bullet -@item the simulation topology and how objects are connected -@item the values used by the models instantiated in the topology -@end itemize - -This chapter focuses on the second item above: how the many values -in use in ns-3 are organized, documented, and modifiable by ns-3 users. -The ns-3 attribute system is also the underpinning of how traces -and statistics are gathered in the simulator. - -Before delving into details of the attribute value system, -it will help to review some basic properties of @code{class ns3::Object}. - -@node Object Overview -@section Object Overview - -ns-3 is fundamentally a C++ object-based system. By this we mean that -new C++ classes (types) can be declared, defined, and subclassed -as usual. - -Many ns-3 objects inherit from the @code{ns3::Object} base class. These -objects have some additional properties that we exploit for -organizing the system and improving the memory management -of our objects: - -@itemize @bullet -@item a "metadata" system that links the class name to a lot of -meta-information about the object, including the base class of the subclass, -the set of accessible constructors in the subclass, and the set of -"attributes" of the subclass -@item a reference counting smart pointer implementation, for memory -management. -@end itemize - -ns-3 objects that use the attribute system derive from either -@code{ns3::Object} or @code{ns3::ObjectBase}. Most ns-3 objects -we will discuss derive from @code{ns3::Object}, but a few that -are outside the smart pointer memory management framework derive -from @code{ns3::ObjectBase}. - -Let's review a couple of properties of these objects. - -@node Smart pointers -@subsection Smart pointers - -As introduced above in @ref{Smart Pointers 101}, ns-3 objects -are memory managed by a -@uref{http://en.wikipedia.org/wiki/Smart_pointer,,reference counting smart pointer implementation}, @code{class ns3::Ptr}. - -Smart pointers are used extensively in the ns-3 APIs, to avoid passing -references to heap-allocated objects that may cause memory leaks. -For most basic usage (syntax), treat a smart pointer like a regular pointer: -@verbatim - Ptr nd = ...; - nd->CallSomeFunction (); - // etc. -@end verbatim - -@node CreateObject -@subsection CreateObject - -As we discussed above in @ref{Object Creation}, -at the lowest-level API, objects of type @code{ns3::Object} are -not instantiated using @code{operator new} as usual but instead by -a templated function called @code{CreateObject()}. - -A typical way to create such an object is as follows: -@verbatim - Ptr nd = CreateObject (); -@end verbatim - -You can think of this as being functionally equivalent to: -@verbatim - WifiNetDevice* nd = new WifiNetDevice (); -@end verbatim - -Objects that derive from @code{ns3::Object} must be allocated -on the heap using CreateObject(). Those deriving from -@code{ns3::ObjectBase}, such as ns-3 helper functions and packet -headers and trailers, can be allocated on the stack. - -In some scripts, you may not see a lot of CreateObject() calls -in the code; -this is because there are some helper objects in effect that -are doing the CreateObject()s for you. - -@node TypeId -@subsection TypeId - -ns-3 classes that derive from class ns3::Object can include -a metadata class called @code{TypeId} that records meta-information -about the class, for use in the object aggregation and component -manager systems: -@itemize @bullet - @item a unique string identifying the class - @item the base class of the subclass, within the metadata system - @item the set of accessible constructors in the subclass -@end itemize - -@node Object Summary -@subsection Object Summary - -Putting all of these concepts together, let's look at a specific -example: @code{class ns3::Node}. - -The public header file node.h has a declaration that includes -a static GetTypeId function call: -@verbatim -class Node : public Object -{ -public: - static TypeId GetTypeId (void); - ... -@end verbatim - -This is defined in the node.cc file as follows: -@verbatim -TypeId -Node::GetTypeId (void) -{ - static TypeId tid = TypeId ("ns3::Node") - .SetParent () - return tid; -} -@end verbatim -Finally, when users want to create Nodes, they call: -@verbatim - Ptr n = CreateObject n; -@end verbatim - -We next discuss how attributes (values associated with member variables -or functions of the class) are plumbed into the above TypeId. - -@node Attribute Overview -@section Attribute Overview - -The goal of the attribute system is to organize the access of -internal member objects of a simulation. This goal arises because, -typically in simulation, users will cut and paste/modify existing -simulation scripts, or will use higher-level simulation constructs, -but often will be interested in studying or tracing particular -internal variables. For instance, use cases such as: -@itemize @bullet -@item "I want to trace the packets on the wireless interface only on -the first access point" -@item "I want to trace the value of the TCP congestion window (every -time it changes) on a particular TCP socket" -@item "I want a dump of all values that were used in my simulation." -@end itemize - -Similarly, users may want fine-grained access to internal -variables in the simulation, or may want to broadly change the -initial value used for a particular parameter in all subsequently -created objects. Finally, users may wish to know what variables -are settable and retrievable in a simulation configuration. This -is not just for direct simulation interaction on the command line; -consider also a (future) graphical user interface -that would like to be able to provide a feature whereby a user -might right-click on an node on the canvas and see a hierarchical, -organized list of parameters that are settable on the node and its -constituent member objects, and help text and default values for -each parameter. - -@node Functional overview -@subsection Functional overview - -We provide a way for users to access values deep in the system, without -having to plumb accessors (pointers) through the system and walk -pointer chains to get to them. Consider a class DropTailQueue that -has a member variable that is an unsigned integer @code{m_maxPackets}; -this member variable controls the depth of the queue. - -If we look at the declaration of DropTailQueue, we see the following: -@verbatim -class DropTailQueue : public Queue { -public: - static TypeId GetTypeId (void); - ... - -private: - std::queue > m_packets; - uint32_t m_maxPackets; -}; -@end verbatim - -Let's consider things that a user may want to do with the value of -m_maxPackets: - -@itemize @bullet -@item Set a default value for the system, such that whenever a new -DropTailQueue is created, this member is initialized to that default. -@item Set or get the value on an already instantiated queue. -@end itemize - -The above things typically require providing Set() and Get() functions, -and some type of global default value. - -In the ns-3 attribute system, these value definitions and accessor -functions are moved into the TypeId class; e.g.: -@verbatim -TypeId DropTailQueue::GetTypeId (void) -{ - static TypeId tid = TypeId ("ns3::DropTailQueue") - .SetParent () - .AddConstructor () - .AddAttribute ("MaxPackets", "The maximum number of packets accepted by this DropTailQueue.", - Uinteger (100), - MakeUintegerAccessor (&DropTailQueue::m_maxPackets), - MakeUintegerChecker ()) - ; - - return tid; -} -@end verbatim - -The AddAttribute() method is performing a number of things with this -value: -@itemize @bullet -@item Binding the variable m_maxPackets to a string "MaxPackets" -@item Providing a default value (100 packets) -@item Providing some help text defining the value -@item Providing a "checker" (not used in this example) that can be used to set -bounds on the allowable range of values -@end itemize - -The key point is that now the value of this variable and its default -value are accessible in the attribute namespace, which is based on -strings such as "MaxPackets" and TypeId strings. In the next -section, we will provide an example script that shows how users -may manipulate these values. - -@node Basic usage -@subsection Basic usage - -Let's look at how a user script might access these values. -This is based on the script found at @code{samples/main-attribute-value.cc}, -with some details stripped out. -@verbatim -// -// This is a basic example of how to use the attribute system to -// set and get a value in the underlying system; namely, an unsigned -// integer of the maximum number of packets in a queue -// - -int -main (int argc, char *argv[]) -{ - - // By default, the MaxPackets attribute has a value of 100 packets - // (this default can be observed in the function DropTailQueue::GetTypeId) - // - // Here, we set it to 80 packets. We could use one of two value types: - // a string-based value or a Uinteger value - Config::SetDefault ("ns3::DropTailQueue::MaxPackets", String ("80")); - // The below function call is redundant - Config::SetDefault ("ns3::DropTailQueue::MaxPackets", Uinteger(80)); - - // Allow the user to override any of the defaults and the above - // SetDefaults() at run-time, via command-line arguments - CommandLine cmd; - cmd.Parse (argc, argv); -@end verbatim - -The main thing to notice in the above are the two calls to -@code{Config::SetDefault}. This is how we set the default value -for all subsequently instantiated DropTailQueues. We illustrate -that two types of Value classes, a String and a Uinteger class, -can be used to assign the value to the attribute named by -"ns3::DropTailQueue::MaxPackets". - -Now, we will create a few objects using the low-level API; here, -our newly created queues will not have a m_maxPackets initialized to -100 packets but to 80 packets, because of what we did above with -default values. -@verbatim - Ptr n0 = CreateObject (); - - Ptr net0 = CreateObject (); - n0->AddDevice (net0); - - Ptr q = CreateObject (); - net0->AddQueue(q); -@end verbatim - -At this point, we have created a single node (Node 0) and a -single PointToPointNetDevice (NetDevice 0) and added a -DropTailQueue to it. - -Now, we can manipulate the MaxPackets value of the already -instantiated DropTailQueue. Here are various ways to do that. - -@subsubsection Pointer-based access - -We assume that a smart pointer (Ptr) to a relevant network device is -in hand; here, it is the net0 pointer. - -One way to change the value is to access a pointer to the -underlying queue and modify its attribute. - -First, we observe that we can get a pointer to the (base class) -queue via the PointToPointNetDevice attributes, where it is called -TxQueue -@verbatim - Ptr txQueue = net0->GetAttribute ("TxQueue"); -@end verbatim - -Using the GetObject function, we can perform a safe downcast -to a DropTailQueue, where MaxPackets is a member -@verbatim - Ptr dtq = txQueue->GetObject (); - NS_ASSERT (dtq); -@end verbatim - -Next, we can get the value of an attribute on this queue -We have introduced wrapper "Value" classes for the underlying -data types, similar to Java wrappers around these types, since -the attribute system stores values and not disparate types. -Here, the attribute value is assigned to a Uinteger, and -the Get() method on this value produces the (unwrapped) uint32_t. -@verbatim - Uinteger limit = dtq->GetAttribute ("MaxPackets"); - NS_LOG_INFO ("1. dtq limit: " << limit.Get () << " packets"); -@end verbatim - -Note that the above downcast is not really needed; we could have -done the same using the Ptr even though the attribute -is a member of the subclass -@verbatim - limit = txQueue->GetAttribute ("MaxPackets"); - NS_LOG_INFO ("2. txQueue limit: " << limit.Get () << " packets"); -@end verbatim - -Now, let's set it to another value (60 packets) -@verbatim - txQueue->SetAttribute("MaxPackets", Uinteger (60)); - limit = txQueue->GetAttribute ("MaxPackets"); - NS_LOG_INFO ("3. txQueue limit changed: " << limit.Get () << " packets"); -@end verbatim - -@subsubsection Namespace-based access - -An alternative way to get at the attribute is to use the configuration -namespace. Here, this attribute resides on a known path in this -namespace; this approach is useful if one doesn't have access to -the underlying pointers and would like to configure a specific -attribute with a single statement. -@verbatim - Config::Set ("/NodeList/0/DeviceList/0/TxQueue/MaxPackets", Uinteger (25)); - limit = txQueue->GetAttribute ("MaxPackets"); - NS_LOG_INFO ("4. txQueue limit changed through namespace: " << - limit.Get () << " packets"); -@end verbatim - -We could have also used wildcards to set this value for all nodes -and all net devices (which in this simple example has the same -effect as the previous Set()) -@verbatim - Config::Set ("/NodeList/*/DeviceList/*/TxQueue/MaxPackets", Uinteger (15)); - limit = txQueue->GetAttribute ("MaxPackets"); - NS_LOG_INFO ("5. txQueue limit changed through wildcarded namespace: " << - limit.Get () << " packets"); -@end verbatim - -@node Setting through constructors and helper classes -@subsection Setting through constructors helper classes - -Arbitrary combinations of attributes can be set and fetched from -the helper and low-level APIs; either from the constructors themselves: -@verbatim -Ptr p = CreateObject ("n1", v1, "n2", v2, ...); -@end verbatim -or from the higher-level helper APIs, such as: -@verbatim - mobility.SetPositionAllocator ("GridPositionAllocator", - "MinX", FpValue (-100.0), - "MinY", FpValue (-100.0), - "DeltaX", FpValue (5.0), - "DeltaY", FpValue (20.0), - "GridWidth", UintValue (20), - "LayoutType", "RowFirst"); -@end verbatim - -@node Value classes -@subsection Value classes -Readers will note the new Value classes. These can be thought of as -an intermediate class that can be used to convert from raw types to the -Values that are used by the system. Recall that this database is holding -objects of many types with a single generic type. Conversions to this -type can either be done using an intermediate class (IntValue, FpValue for -"floating point") or via strings. Direct implicit conversion of types -to Value is not really practical. So in the above, users have a choice -of using strings or values: -@verbatim -p->Set ("cwnd", "100"); // string-based setter -p->Set ("cwnd", IntValue(100)); // value-based setter -@end verbatim - -The system provides some macros that help users declare and define -new Value subclasses for new types that they want to introduce into -the attribute system. - -@node Extending attributes -@section Extending attributes - -The ns-3 system will place a number of internal values under the -attribute system, but undoubtedly users will want to extend this -to pick up ones we have missed, or to add their own classes to this. - -@subsection Adding an existing internal variable to the metadata system - -// XXX revise me - -Consider this variable in class TcpSocket: -@verbatim - uint32_t m_cWnd; // Congestion window -@end verbatim - -Suppose that someone working with Tcp wanted to get or set the -value of that variable using the metadata system. If it were not -already provided by ns-3, the user could declare the following addition -in the metadata system (to the TypeId declaration for TcpSocket): -@verbatim - .AddParameter ("Congestion window", - "Tcp congestion window (bytes)", - MakeUIntParamSpec (&TcpSocket::m_cWnd, 1)); - -@end verbatim - -Now, the user with a pointer to the TcpSocket can perform operations -such as setting and getting the value, without having to add these -functions explicitly. Furthermore, access controls can be applied, such -as allowing the parameter to be read and not written, or bounds -checking on the permissible values can be applied. - -@subsection Adding a new TypeId - -Here, we discuss the impact on a user who wants to add a new class to -ns-3; what additional things must be done to hook it into this system. - -We've already introduced what a TypeId definition looks like: -@verbatim -TypeId -RandomWalk2dMobilityModel::GetTypeId (void) -{ - static TypeId tid = TypeId ("RandomWalkMobilityModel") - .SetParent () - .SetGroupName ("Mobility") - .AddConstructor () - // followed by a number of Parameters - .AddParameter ("bounds", - "Bounds of the area to cruise.", - MakeRectangleParamSpec (&RandomWalk2dMobilityModel::m_bounds, Rectangle (0.0, 0.0, 100.0, 100.0))) - .AddParameter ("time", - "Change current direction and speed after moving for this delay.", - MakeTimeParamSpec (&RandomWalk2dMobilityModel::m_modeTime, - Seconds (1.0))) - - // etc (more parameters). -@end verbatim - -The declaration for this in the class declaration is one-line public -member method: -@verbatim - public: - static TypeId GetTypeId (void); -@end verbatim - -@section Adding new class type to the Value system - -From the perspective of the user who writes a new class in the system and -wants to hook it in to the attribute system, there is mainly the matter -of writing -the conversions to/from strings and Values. Most of this can be -copy/pasted with macro-ized code. For instance, consider class -Rectangle in the @code{src/mobility/} directory: - -One line is added to the class declaration: -@verbatim -/** - * \brief a 2d rectangle - */ -class Rectangle -{ -... - - VALUE_HELPER_HEADER_1 (Rectangle); -}; -@end verbatim - -One templatized declaration, and two operators, are added below the -class declaration: - -@verbatim -std::ostream &operator << (std::ostream &os, const Rectangle &rectangle); -std::istream &operator >> (std::istream &is, Rectangle &rectangle); - -VALUE_HELPER_HEADER_2 (Rectangle); -@end verbatim - -In the class definition, the code looks like this: - -@verbatim -VALUE_HELPER_CPP (Rectangle); - -std::ostream & -operator << (std::ostream &os, const Rectangle &rectangle) -{ - os << rectangle.xMin << "|" << rectangle.xMax << "|" << rectangle.yMin << "|" << rectangle.yMax; - return os; -} -std::istream & -operator >> (std::istream &is, Rectangle &rectangle) - { - char c1, c2, c3; - is >> rectangle.xMin >> c1 >> rectangle.xMax >> c2 >> rectangle.yMin >> c3 >> rectangle.yMax; - if (c1 != '|' || - c2 != '|' || - c3 != '|') - { - is.setstate (std::ios_base::failbit); - } - return is; -} -@end verbatim - -These stream operators simply convert from a string representation of the -Rectangle ("xMin|xMax|yMin|yMax") to the underlying Rectangle, and the -modeler must specify these operators and the string syntactical representation -of an instance of the new class. - diff --git a/doc/tutorial/in-process/helpers.texi b/doc/tutorial/in-process/helpers.texi deleted file mode 100644 index b64858173..000000000 --- a/doc/tutorial/in-process/helpers.texi +++ /dev/null @@ -1,20 +0,0 @@ -@node Helper Functions -@chapter Helper Functions -@anchor{chap:Helpers} -This chapter describes an intermediate API for the simulator; what we -call the "helper API". The helper API is implemented in -@code{src/helper/} directory; it depends on (and wraps) the low-level -API which is implemented everywhere else in @code{src/}. The following -figure shows this relationship. -@center @image{figures/helpers,,,,png} - -The use of the helper API is optional. It has two main goals: -@itemize @bullet -@item Provide "syntactic sugar" to wrap a number of related low-level -API calls together, that would normally be grouped together often, into -something that is more user-friendly. -@item Handle configuration of larger topological units (e.g., a set -of nodes or a set of nodes on a particular link) . -@end itemize - -(more to follow) diff --git a/doc/tutorial/in-process/introduction.texi b/doc/tutorial/in-process/introduction.texi deleted file mode 100644 index 0aa87389e..000000000 --- a/doc/tutorial/in-process/introduction.texi +++ /dev/null @@ -1,2034 +0,0 @@ - -@c ======================================================================== -@c Begin document body here -@c ======================================================================== - -@c ======================================================================== -@c Tutorial Goals -@c ======================================================================== - -@node Tutorial Goals -@unnumbered Tutorial Goals - -@c This is an unnumbered section, like a preface. Numbering -@c starts with section 1 (Introduction) - -The goal of this ns-3 tutorial is to introduce new users of ns-3 to enough -of the system to enable them to author simple simulation scripts and extract -useful information from the simulations. We begin by introducing some of the -other important resources that are available to those interested in using or -writing scripts, models and even those interested in making contributions to -the core ns-3 system. We provide an overview of some of the -important abstractions, design patterns and idioms used when writing -ns-3 scripts, and then dig right in by beginning to write simulation -scripts, run them and interpret results. - -After completing this tutorial, one should be able to: -@itemize @bullet -@item Find documentation resources in the distribution and on the web; -@item Download and compile the ns-3 system; -@item Understand the key software conventions of ns-3; -@item Modify configuration parameters of existing scripts; -@item Change the simulation output (tracing, logging, statistics); -@item Extend the simulator to use new objects -@item Write new ns-3 applications; -@item See how to port code from ns-2; -@item ... (more to follow) -@end itemize - -@c ======================================================================== -@c PART: Introduction -@c ======================================================================== -@c The below chapters are under the major heading "Introduction" -@c This is similar to the Latex \part command -@c -@c ======================================================================== -@c Overview -@c ======================================================================== -@node Overview -@chapter Overview - -@menu -* For ns-2 users:: -* Contributing:: -* Tutorial organization:: -@end menu - -The ns-3 simulator is a discrete-event network -simulator targeted primarily for research and educational use. -The @uref{http://www.nsnam.org,,ns-3 project}, started in -2006, is an open-source project. The goal of the project is to -build a new network simulator primarily for research and educational use. - -Primary documentation for the ns-3 project is available in -three forms: -@itemize @bullet -@item @uref{http://www.nsnam.org/doxygen/index.html,,ns-3 Doxygen/Manual}: Documentation of the public APIs of the simulator -@item Tutorial (this document) -@item @uref{http://www.nsnam.org/wiki/index.php,, ns-3 wiki} -@end itemize - -The purpose of this tutorial is to introduce new ns-3 users to the -system in a structured way. It is sometimes difficult for new users to -glean essential information from detailed manuals and to convert this -information into working simulations. In this tutorial, we will build -several example simulations, introducing and explaining key concepts and -features as we go. - -As the tutorial unfolds, we will introduce the full ns-3 -documentation -and provide pointers to source code for those interested in delving deeper -into the workings of the system. - -A few key points are worth noting at the onset: -@itemize @bullet -@item ns-3 is not an extension of @uref{http://www.isi.edu/nsnam/ns,,ns-2}; -it is a new -simulator. The two simulators are both written in C++ but ns-3 -is a new simulator that does not support the ns-2 APIs. -Some models from ns-2 have already been ported from ns-2 -to ns-3. The project will continue to maintain ns-2 while -ns-3 is being built, and will study transition and -integration mechanisms. -@item ns-3 is open-source, and the project strives to maintain -an open environment for researchers to contribute and share their -software. -@end itemize - -@node For ns-2 users -@section For ns-2 users - -For those familiar with ns-2, the most visible outward change -when moving to ns-3 is the choice of scripting language. -ns-2 is typically scripted in Tcl and results of simulations can -be visualized using the Network Animator @command{nam}. In -ns-3 there is currently no visualization module, and Python -bindings have been developed (Tcl bindings have been prototyped -using @uref{http://www.swig.org,,SWIG}, but are not supported by the -current development team). -In this tutorial, we will concentrate on -scripting directly in C++ and interpreting results via trace files. - -But there are similarities as well (both, for example, are based -on C++ objects, and some code from ns-2 has already been ported -to ns-3). We will try to highlight differences between ns-2 and ns-3 -as we proceed in this tutorial. - -@node Contributing -@section Contributing - -@cindex software configuration management -ns-3 is a research and educational simulator, by and for the -research community. It will rely on the ongoing contributions of -the community to develop new models, debug or maintain -existing ones, and share results. There are a few policies -that we hope will encourage people to contribute to ns-3 like they -have for ns-2: -@itemize @bullet -@item open source licensing based on GNU GPLv2 compatibility -@item @uref{http://www.nsnam.org/wiki/index.php,,wiki} -@item @uref{http://www.nsnam.org/wiki/index.php/Contributed_Code,,Contributed Code} page, similar to ns-2's popular -@uref{http://nsnam.isi.edu/nsnam/index.php/Contributed_Code,,Contributed Code} -page -@item @code{src/contrib} directory (we will host your contributed code) -@item open @uref{http://www.nsnam.org/bugzilla,,bug tracker} -@item ns-3 developers will gladly help potential contributors to get -started with the simulator (please contact @uref{http://www.nsnam.org/people.html,,one of us}) -@end itemize - -If you are an ns user, please consider to provide your feedback, -bug fixes, or code to the project. - -@node Tutorial organization -@section Tutorial organization - -The tutorial assumes that new users might follow a path such as follows: - -@itemize @bullet -@item browse the source code and documentation, to get a feel for -the simulator and what it might be like to handle; -@item try to download and build a copy; -@item try to run a few sample programs, and perhaps change some configurations; -@item look at simulation output, and try to adjust it -@item study the software architecture of the system, to consider hacking it or -extending it; -@item write new models or port existing code to ns-3, and eventually post those -models back to the community. -@end itemize - -As a result, we have tried to organize the tutorial along the above -broad sequences of events. - -@c ======================================================================== -@c Browsing ns-3 -@c ======================================================================== - -@node Browsing -@chapter Browsing ns-3 - -@menu -* Source code:: -* Doxygen:: -* Other documentation:: -@end menu - -@node Source code -@section Source code - -The most recent code can be browsed on our web server at the following link: -@uref{http://code.nsnam.org/?sort=lastchange}. If you click on the bold -repository names on the left of the page, you will see changelogs for -these repositories, and links to the @emph{manifest}. From the manifest -links, one can browse the source tree. - -The top-level directory will look something like: -@verbatim - AUTHORS RELEASE_NOTES examples/ src/ waf* - LICENSE VERSION ns3/ tutorial/ waf.bat* - README doc/ samples/ utils/ wscript -@end verbatim -The source code is mainly in the @code{src} directory. Example -scripts are in the @code{examples} directory. Both are good directories -to start browsing some code. - -For ns-2 users, who may be familiar with the @code{simple.tcl} example script -in the ns-2 documentation, an analogous script is found in -@code{examples/simple-point-to-point.cc} with a Python equivalent found -in @emph{(pending Python merge)}. - -@node Doxygen -@section Doxygen - -We document all of APIs using @uref{http://www.stack.nl/~dimitri/doxygen/,,Doxygen}. Current builds of this documentation are available at: -@uref{http://www.nsnam.org/doxygen/index.html}, which are worth an initial -look. - -@node Other documentation -@section Other documentation - -See: @uref{http://www.nsnam.org/documents.html}. - -@c ======================================================================== -@c Resources -@c ======================================================================== - -@node Resources -@chapter Resources - -@menu -* The-Web:: -* Mercurial:: -* Waf:: -* Environment-Idioms-Design-Patterns:: -* Socket-Programming:: -@end menu - -@node The-Web -@section The Web - -@cindex www.nsnam.org -There are several important resources of which any ns-3 user must be -aware. The main web site is located at @uref{http://www.nsnam.org} -and provides access to basic information about the ns-3 system. -Detailed documentation is available through the main web site at -@uref{http://www.nsnam.org/documents.html}. - -@cindex documentation -@cindex architecture -You can find documents relating to the system architecture from this page, -and also gain access to the detailed software documentation. The software -system is documented in great detail using -@uref{http://www.stack.nl/~dimitri/doxygen/,,Doxygen}. There is a Wiki that -complements the main ns-3 web site which you will find at -@uref{http://www.nsnam.org/wiki/}. - -You will find user and developer FAQs there as well as troubleshooting guides, -third-party contributed code, papers, etc. The source code may be found -and browsed at @uref{http://code.nsnam.org/}. - -@cindex repository!ns-3-dev -@cindex repository!releases -There you will find the current development tree in the repository named -@code{ns-3-dev}. Past releases and experimental repositories of the core -developers may also be found there. - -@node Mercurial -@section Mercurial - -Complex software systems need some way to manage the organization and -changes to the underlying code and documentation. There are many ways to -perform this feat, and you may have heard of some of the systems that are -currently used to do this. The Concurrent Version System (CVS) is probably -the most well known. - -@cindex software configuration management -@cindex Mercurial -The ns-3 project uses Mercurial as its source code management system. -Although you do not need to know much about Mercurial in order to complete -this tutorial, we recommend becoming familiar with Mercurial and using it -to access the source code. Mercurial has a web site at -@uref{http://www.selenic.com/mercurial/}, -from which you can get binary or source releases of this Software -Configuration Management (SCM) system. Selenic (the developer of Mercurial) -also provides a tutorial at -@uref{http://www.selenic.com/mercurial/wiki/index.cgi/Tutorial/}, -and a QuickStart guide at -@uref{http://www.selenic.com/mercurial/wiki/index.cgi/QuickStart/}. - -You can also find vital information about using Mercurial and ns-3 -on the main ns-3 web site. - -@node Waf -@section Waf - -@cindex Waf -@cindex make -@cindex build -Once you have source code downloaded to your local system, you will need -to compile that source to produce usable programs. Just as in the case of -source code management, there are many tools available to perform this -function. Probably the most famous of these tools is @code{make}. Along -with being the most famous, @code{make} is probably the most difficult to -use in a very large and highly configurable system. Because of this, many -alternatives have been developed. Recently these systems have been developed -using the Python language. - -The build system @code{Waf} is used on the ns-3 project. It is one -of the new generation of Python-based build systems. You will not need to -understand any Python to build the existing ns-3 system, and will -only have to understand a tiny and intuitively obvious subset of Python in -order to extend the system in most cases. - -For those interested in the gory details of Waf, the main web site can be -found at @uref{http://freehackers.org/\~tnagy/waf.html}. - -@node Environment-Idioms-Design-Patterns -@section Environment, Idioms, and Design Patterns - -@cindex C++ -As mentioned above, scripting in ns-3 is done in C++. A working -knowledge of C++ and object-oriented concepts is assumed in this document. -We will take some time to review some of the more advanced concepts or -possibly unfamiliar language features, idioms and design patterns as they -appear. We don't want this tutorial to devolve into a C++ tutorial, though, -so we do expect a basic command of the language. There are an almost -unimaginable number of sources of information on C++ available on the web or -in print. - -If you are new to C++, you may want to find a tutorial- or cookbook-based -book or web site and work through at least the basic features of the language -before proceeding. - -@subsection Environment - -@cindex toolchain -@cindex GNU -The ns-3 system uses the GNU ``toolchain'' for development. -A software toolchain is the set of programming tools available in the given -environment. For a quick review of what is included in the GNU toolchain see, -@uref{http://en.wikipedia.org/wiki/GNU_toolchain}. - -@cindex Linux -Typically an ns-3 author will work in Linux or a Linux-like -environment. For those running under Windows, there do exist environments -which simulate the Linux environment to various degrees. The ns-3 -project supports development in the Cygwin and the MinGW environments for -these users. See @uref{http://www.cygwin.com/} and -@uref{http://www.mingw.org/} for details on downloading and using these -systems. Cygwin provides many of the popular Linux system commands. -It can, however, sometimes be problematic due to the way it -actually does its emulation, and sometimes interactions with other Windows -software can cause problems. - -@cindex Cygwin -@cindex MinGW -If you do use Cygwin or MinGW; and use Logitech products, we will save you -quite a bit of heartburn right off the bat and encourage you to take a look -at the @uref{http://www.mingw.org/MinGWiki/index.php/FAQ,,MinGW FAQ}. - -@cindex Logitech -Search for ``Logitech'' and read the FAQ entry, ``why does make often -crash creating a sh.exe.stackdump file when I try to compile my source code.'' -Believe it or not, the @code{Logitech Process Monitor} insinuates itself into -every DLL in the system when it is running. It can cause your Cygwin or -MinGW DLLs to die in mysterious ways and often prevents debuggers from -running. Beware of Logitech. - -@subsection Idioms and Design Patterns - -@cindex idiom -In any system, there are a number of problems to be solved that happen -repeatedly. Often the solutions to these problems can be generalized and -applied in a similar way across the system. These solutions are called -Design Patterns. The ns-3 system relies on several classic design -patterns. - -@cindex design pattern -Also, in any language, there are constructs that, while they aren't part of the -language per se, are commonly found and useful. For example, at the lowest -level a C programmer should be able to immediately recognize the purpose and -intent of the following code without having to reflect on the details: - -@verbatim - for (;;) -@end verbatim - -These low-level constructs, or idioms, extend upward in complexity, eventually -becoming implementations of design patterns. As you are exposed to more -and more of the ns-3 system, you will begin to recognize and be -comfortable with the C++ implementations (idioms) of several important design -patterns. - -@cindex functor -@cindex callback -@cindex smart pointer -The ns-3 code relies heavily on -@emph{Generalized Functors, Callbacks, -Smart Pointers, Singletons, and Object Factories}. Although we will -not assume any detailed knowledge of the idioms and design patterns used -in the ns-3 -system, it will be useful for readers who intend to delve deeply into the -system to understand some important related concepts. We recommend two -resources: @uref{http://www.amazon.com/Design-Patterns-Object-Oriented-Addison-Wesley-Professional/dp/0201633612/,,Design Patterns: Elements of Reusable Object-Oriented Software, Gamma et. al.} and -@uref{http://www.amazon.com/exec/obidos/ASIN/0201704315,,Modern C++ Design: Generic Programming and Design Patterns Applied, Alexandrescu}. - -Gamma addresses the abstract design patterns, and Alexandrescu addresses the -C++ idioms you will often see throughout the ns-3 code. - -@cindex template -Almost any use of ns-3 will require some basic knowledge of C++ -templates. -We will discuss the high-level uses in this tutorial. However, if you venture -deeply into the source code, you will see fairly heavy use of relatively -sophisticated C++ templates in some of low-level modules of the system. The -You don't have to be a template guru to complete this tutorial but if you -expect to work in ns-3 within the simulation core, you will have to be -somewhat fluent -with templates. If you want to truly grok C++ templates we recommend, -@uref{http://www.amazon.com/Templates-Complete-Guide-David-Vandevoorde/dp/0201734842/,,C++ Templates: The Complete Guide, Vandevoorde and Josuttis}. - -@node Socket-Programming -@section Socket Programming - -@cindex sockets -We will assume a basic facility with the Berkeley Sockets API in the examples -used in this tutorial. If you are new to sockets, we recommend reviewing the -API and some common usage cases. For a good overview of programming TCP/IP -sockets we recommend @uref{http://www.elsevier.com/wps/product/cws_home/680765,,Practical TCP/IP Sockets in C, Donahoo and Calvert}. - -There is an associated web site that includes source for the examples in the -book, which you can find at: -@uref{http://cs.baylor.edu/~donahoo/practical/CSockets/}. - -If you understand the first four chapters of the book (or for those who do -not have access to a copy of the book, the echo clients and servers shown in -the website above) you will be in good shape to understand the tutorial. -There is a similar book on Multicast Sockets, -@uref{http://www.elsevier.com/wps/product/cws_home/700736,,Multicast Sockets, Makofske and Almeroth}. -that covers material you may need to understand for the multicast examples. - -@c ======================================================================== -@c Downloading and Compiling -@c ======================================================================== - -@node Downloading and Compiling -@chapter Downloading and Compiling - -@cindex Linux -@cindex Cygwin -@cindex GNU -@cindex toolchain -From this point forward, we are going to assume that the reader is working in -Linux or a Linux emulation environment (Linux, Cygwin, etc.) and has the GNU -toolchain installed and verified. - -@cindex Mercurial -@cindex Waf -We are going to assume that you have Mercurial and Waf installed and running -on the target system as described in the Getting Started section of the -ns-3 web site: @uref{http://www.nsnam.org/getting_started.html}. - -@section Downloading -@cindex tarball -The ns-3 code is available in Mercurial repositories on the server -code.nsnam.org. You can download a tarball, but we recommend working with -Mercurial --- it will make your life easier in the long run. - -@cindex repository -If you go to the following link: @uref{http://code.nsnam.org/}, -you will see a number of repositories. Many are the private repositories of -the ns-3 development team. The repositories of interest to you -will be -prefixed with ``ns-3''. The current development snapshot (unreleased) of -ns-3 may be found at: @uref{http://code.nsnam.org/ns-3-dev/}. - -The developers attempt to keep this repository in a consistent, working state -but it is a development area with unreleased code present, so you may want to -consider downloading an official release. - -There will be a number of released repositories present at code.nsnam.org. -These repos will have names like ns-3.0.1 --- which referes to release 3.0.1 -of the network simulator (or if you like, release 0.1 of ns-3). -Since the releases are changing at a rate of one per month, I will stick with -the more constant ns-3-dev here, but you can replace the string ns-3-dev with -your choice of release (e.g., ns-3.0.5) below. You can find the latest -version of the code either by inspection of the repository list or by going -to the ``Getting Started'' web page and looking for the latest release -identifier. - -One practice is to create a directory called @code{repos} in one's home -directory under which one can keep local Mercurial repositories. -@emph{Hint: we will -assume you do this later in the tutorial.} If you adopt that approach, you -can get a copy of any of the development versions of ns-3 by typing -the following into your Linux shell (assuming you have installed Mercurial): - -@verbatim - cd - mkdir repos - cd !$ - hg clone http://code.nsnam.org/ns-3-dev -@end verbatim - -As the hg command executes, you should see something like the following, - -@verbatim - destination directory: ns-3-dev - requesting all changes - adding changesets - adding manifests - adding file changes - added 1513 changesets with 5687 changes to 733 files - 358 files updated, 0 files merged, 0 files removed, 0 files unresolved -@end verbatim - -After the clone command completes, you should have a directory called -ns-3-dev under your @code{~/repos} directory, the contents of which should -look something like the following: - -@verbatim - AUTHORS RELEASE_NOTES examples/ src/ waf* - LICENSE VERSION ns3/ tutorial/ waf.bat* - README doc/ samples/ utils/ wscript -@end verbatim - -You are now ready to build the ns-3 distribution. - -@section Building -@cindex Waf!build -@cindex Waf!configure -@cindex Waf!debug -@cindex Waf!compile -We use Waf to build the ns-3 project. The first thing you -will need to do is to configure the build. For reasons that will become clear -later, we are going to work with debug builds in the tutorial. To explain to -Waf that it should do debug builds you will need to execute the following -command, - -@verbatim - ./waf -d debug configure -@end verbatim - -This runs the copy of Waf in the local directory (which is provided as a -convenience for you). As the build system checks for various dependencies -you should see output that looks similar to the following, - -@verbatim - ~/repos/ns-3-dev >./waf -d debug configure - Checking for program g++ : ok /usr/bin/g++ - Checking for program cpp : ok /usr/bin/cpp - Checking for program ar : ok /usr/bin/ar - Checking for program ranlib : ok /usr/bin/ranlib - Checking for compiler could create programs : ok - Checking for compiler could create shared libs : ok - Checking for compiler could create static libs : ok - Checking for flags -Wall : ok - Checking for flags -O2 : ok - Checking for flags -g -DDEBUG : ok - Checking for flags -g3 -O0 -DDEBUG : ok - Checking for g++ : ok - Checking for header stdlib.h : ok - Checking for header stdlib.h : ok - Checking for header signal.h : ok - Checking for high precision time implementation: 128-bit integer - Checking for header stdint.h : ok - Checking for header inttypes.h : ok - Checking for header sys/inttypes.h : not found - Configuration finished successfully; project is now ready to build. - ~/repos/ns-3-dev > -@end verbatim - -The build system is now configured and you can build the debug versions of -the ns-3 programs by simply typing, - -@verbatim - ./waf --check -@end verbatim - -You will see many Waf status messages displayed as the system compiles. The -most important is the last one, - -@verbatim - Compilation finished successfully -@end verbatim - -and you will see a number of software unit tests subsequently execute. - -@section Running a Script -@cindex Waf!run -We typically run scripts under the control of Waf. This allows the build -system to ensure that the shared library paths are set correctly and that -the libraries are available at run time. To run a program, simply use the -@code{run} option in Waf. Let's run the ns-3 equivalent of the hello -world program by typing the following: - -@verbatim - ./waf --run hello-simulator -@end verbatim - -Waf first checks to make sure that the program is built correctly and -executes a build if required. Waf then then executes the program, which -produces the following output. - -@verbatim - Hello Simulator -@end verbatim - -If you want to run programs under another tool such as gdb or valgrind, -see this @uref{http://www.nsnam.org/wiki/index.php/User_FAQ#How_to_run_NS-3_programs_under_another_tool,,wiki entry}. - -@emph{Congratulations. You are now an ns-3 user.} - -@c ======================================================================== -@c Some Prerequisites -@c ======================================================================== - -@node Some-Prerequisites -@chapter Some Prerequisites - -The first thing we need to do before actually starting to code is to explain -a few core concepts, abstractions and idioms in the system. Much of this may -appear transparently obvious to some, but we recommend taking the time to read -through this chapter just to ensure you are starting on a firm foundation. - -@section Abstractions - -In this section, we'll review some terms that are commonly used in -networking, but have a specific meaning in ns-3. - -@subsection Node -@cindex Node -In Internet jargon, a computing device that connects to a network is called -a @emph{host} or sometimes an @emph{end system}. Because ns-3 is a -@emph{network} simulator, not specifically an @emph{Internet} simulator, we -intentionally do not use the term host since it is closely associated with -the Internet and its protocols. Instead, we use a more generic term also -used by other simulators that originates in Graph Theory --- the @emph{node}. - -@cindex Node!class -In ns-3 the basic computing device abstraction is called the -node. This abstraction is represented in C++ by the class @code{Node}. The -@code{Node} class provides methods for managing the representations of -computing devices in simulations. Developers are expected to specialize the -@code{Node} in the object-oriented programming sense to create new computing -device models. In this tutorial, we will use a specialization of class -@code{Node} called @code{InternetNode}. As you might expect, the -@code{InternetNode} is a class that represents a host in the Internet sense, -and automatically provides core IPv4 networking protocols. - -You should think of a @code{Node} as a computer to which you will add -functionality. One adds things like applications, protocol stacks and -peripheral cards with their associated drivers to enable the computer to do -useful work. We use the same basic model in ns-3. - -@subsection Application -@cindex Application -Typically, computer software is divided into two broad classes. @emph{System -Software} organizes various computer resources such as memory, processor -cycles, disk, network, etc., according to some computing model. System -software usually does not use those resources to complete tasks that directly -benefit a user. A user would typically run an @emph{application} that acquires -and uses the resources controlled by the system software to accomplish some -goal. - -@cindex system call -Often, the line of separation between system and application software is made -at the privilege level change that happens in operating system traps. -In ns-3 there is no real concept of operating system and especially -no concept of privilege levels or system calls. We do, however, have the -idea of an application. Just as software applications run on computers to -perform tasks in the ``real world,'' ns-3 applications run on -ns-3 @code{Node}s to drive simulations in the simulated world. - -@cindex Application!class -In ns-3 the basic abstraction for a user program that generates some -activity to be simulated is the application. This abstraction is represented -in C++ by the class @code{Application}. The @code{Application} class provides -methods for managing the representations of our version of user-level -applications in simulations. Developers are expected to specialize the -@code{Application} in the object-oriented programming sense to create new -applications. In this tutorial, we will use specializations of class -@code{Application} called @code{UdpEchoClient} and @code{UdpEchoServer}. -As you might expect, these applications compose a client/server application set -used to generate and echo simulated network packets - -@subsection Channel -@cindex Channel - -In the real world, one can connect a computer to a network. Often the media -over which data flows in these networks are called @emph{channels}. When -you connect your Ethernet cable to the plug in the wall, you are connecting -your computer to an Ethernet communication channel. In the simulated world -of ns-3 one connects a @code{Node} to an object representing a -communication channel. Here the basic communication subnetwork abstraction -is called the channel and is represented in C++ by the class @code{Channel}. - -The @code{Channel} class provides methods for managing communication -subnetwork objects and connecting nodes to them. They may also be specialized -by developers in the object oriented programming sense. A @code{Channel} -specialization may model something as simple as a wire. The specialized -@code{Channel} can also model things as complicated as a large Ethernet -switch, or three-dimensional space in the case of wireless networks. - -We will use specialized versions of the @code{Channel} called -@code{CsmaChannel} and @code{PointToPointChannel} in this tutorial. The -@code{CsmaChannel}, for example, models a version of a communication subnetwork -that implements a @emph{carrier sense multiple access} communication medium. -This gives us Ethernet-like functionality. - -@subsection Net Device -@cindex NetDevice -@cindex Ethernet - -It used to be the case that if you wanted to connect a computers to a network, -you had to buy a specific kind of network cable and a hardware device called -(in PC terminology) a @emph{peripheral card} that needed to be installed in -your computer. These cards were called Network Interface Cards, or -@emph{NIC}s. Today most computers come with the network controller hardware -built in and users don't see these building blocks. - -A NIC will not work without a software driver to control the hardware. In -Unix (or Linux), a piece of peripheral hardware is classified as a -@emph{device}. Devices are controlled using @emph{device drivers}, and network -devices (NICs) are controlled using @emph{network device drivers} -collectively known as @emph{net devices}. In Unix and Linux you refer -to these net devices by names such as @emph{eth0}. - -In ns-3 the @emph{net device} abstraction covers both the software -driver and the simulated hardware. A net device is ``attached'' to a -@code{Node} in order to enable the @code{Node} to communicate with other -@code{Node}s in the simulation via @code{Channel}s. Just as in a real -computer, a @code{Node} may be connected to more than one @code{Channel} via -multiple @code{NetDevice}s. - -The net device abstraction is represented in C++ by the class @code{NetDevice}. -The @code{NetDevice} class provides methods for managing connections to -@code{Node} and @code{Channel} objects; and may be specialized by developers -in the object-oriented programming sense. We will use the specialized version -of the @code{NetDevice} called the @code{CsmaNetDevice} in this tutorial. -Just as an Ethernet NIC is designed to work with an Ethernet network, the -@code{CsmaNetDevice} is designed to work with a @code{CsmaChannel}. - -@subsection Topology Helpers -In a real network, you will find host computers with added (or built-in) -NICs. In ns-3 we would say that you will find @code{Nodes} with -attached @code{NetDevices}. In a large simulated network you will need to -arrange many connections between @code{Node}s, @code{NetDevice}s and -@code{Channel}s. - -Since connecting a @code{NetDevice} to a @code{Node}, and a @code{NetDevice} -to a @code{Channel} is such a common task in ns-3 we provide what we -call @emph{topology helpers} to make this as easy as possible. Topology -helpers perform much of the dirty work of creating and connecting net devices. -For example, it may take several distinct method calls to create a NetDevice, -add a MAC address, connect the net device to a @code{Node} and configure -the protocol stack, and then connect the @code{NetDevice} to a @code{Channel}. -We use topology helper functions to compose those distinct operations into -an easy to use model. - -Topology helper functions use the abstractions (described above) of Network -Interface Cards and Cables. When you think of adding a new kind of network, -you may think of going out to the local computer retailer and buying a kit. -This kit might include a network cable and some number of peripheral cards and -their associated software drivers. You can think of topology helpers in -roughly the same way. Instead of buying a kit for a given type of network, -you will use a topology helper class for a given type of network, to accomplish -the equivalent of installing the network ``kit.'' - -@section Important Idioms -Now that we have identified that there are C++ classes in the system called -@code{Node} and @code{InternetNode}, we need to understand how to bring -objects of these classes into existence, and manage their lifetimes. Let's -examine this in some detail here. - -@cindex InternetNode -@cindex CreateObject -@cindex Ptr -In ns-3, if we want to create an @code{InternetNode} in a -script, we will -typically do something like the following example: - -@verbatim - Ptr p = CreateObject (); -@end verbatim - -@cindex smart pointer -To some, it may seem intuitively obvious that we're creating an -@code{InternetNode} object and assigning responsibility for managing the -object to a smart pointer named @code{p}. For the rest of us, there may be -a lot in that line that is unfamiliar, so let's look at what this line means -in some detail. - -@subsection Templates 101 -@cindex template -If you are familiar with C++ templates, you may skip this section as it is -just a cursory introduction to function and class templates. - -Referring back to the example line of code, reproduced below for your -convenience, the angle brackets you see in the code indicate that we are -using C++ @emph{templates}. - -@verbatim - Ptr p = CreateObject (); -@end verbatim - -The purpose of templates is to allow a programmer to write one version of code -that is applicable over multiple types. Some people consider templates to be -an enhancement of the C preprocessor macro functionality. At some level -this comparison reveal some similarities, but C++ templates are really -quite different. - -@cindex template!declaration -@cindex template!definition -@cindex template!use -In C++, just as with most language constructs, templates are @emph{declared}, -@emph{defined} and @emph{used}. A declaration of a template might look -something like, - -@verbatim - template T Add (T first, T second); -@end verbatim - -@cindex template!typename -This line uses the keyword @code{template} followed by a declaration of a -type name (in this case @code{T}) in angle brackets. The angle brackets -should indicate to you that a template is being declared, defined or used. -The type name @code{T} can be thought of as a string that will be substitited -during the use phase of the template. For example, the @code{T} may be -replaced by the word @code{int}. It is this substitution that leads people -to compare templates with macros. - -Without going into too much more detail, this snippet declares that a piece -of code exists that will be able to call a function @code{Add} that will -add arbitrary types together. The @code{T} will be eventually replaced by -a C++ data type name. For example, - -@verbatim - T Add (T first, T second); -@end verbatim - -might eventually become - -@verbatim - int Add (int first, int second); -@end verbatim - -If the template has been declared, we need to @emph{define} what that piece of -code will actually do. That might look something like, - -@verbatim - template - T Add (T first, T second) - { - return first + second; - } -@end verbatim - -All we've done here is to provide an implementation of the template that -adds the two variables together and returns the result. Note that this -implementation works for any type that provides an @code{operator+}. - -The puzzle all comes together when you understand that @emph{using} a template -causes the compiler to automatically instantiate code for a specific function -according to the given template parameters. You might use the above template -like, - -@verbatim - int x, y, z; - z = Add (x, y); -@end verbatim - -@cindex template!instantiate -When the compiler sees @code{Add} it understands that it needs to make -sure that code is instantiated (created) to perform the @code{Add} using the -specified type @code{}. To a first approximation, the compiler will -replace the typename @code{T} with the specified type @code{int} and -automagically generate code equivalent to, - -@verbatim - int Add (int first, int second) - { - return first + second; - } -@end verbatim - -A user of the template definition could just as easily have provided a use -that assigned the type float. This would simply be done like, - -@verbatim - float x, y, z; - z = Add (x, y); -@end verbatim - -In this case, the compiler would automatically generate code that looked like, - -@verbatim - float Add (float first, float second) - { - return first + second; - } -@end verbatim - -@cindex template!function -This particular kind of template programming uses what are called -@emph{function templates}. They are called function templates since you -are @emph{templating} function declarations and definitions. - -@cindex template!class -Templates can also be used in conjunction with classes, in which case you are -said to be using, not too surprisingly, @emph{class templates}. The syntax and -use is similar. To declare a class template you might use something like, - -@verbatim - template - class MyStack - { - void Push (T data); - T Pop (void); - }; -@end verbatim - -The methods can be defined separately in a method similar to function template -definitions, - -@verbatim - template void MyStack::Push (T data) - { - ... - }; -@end verbatim - -You can then use the new templated class in the following way, - -@verbatim - int x, y; - - MyStack stack; - stack.Push (x); - y = stack.Pop (); -@end verbatim - -Similarly to the function template case, the compiler knows that it has to -automatically generate code to fill out the class and method declarations -and definitions using the appropriate type specified by @code{}. - -@node Smart Pointers 101 -@subsection Smart Pointers 101 -If you are familiar with C++ smart pointers, you may skip this section as it -is just a cursory introduction to smart pointers and intrusive reference -counting. - -@cindex smart pointer -Referring back to the example line of code, partially reproduced below for -your convenience below, the left hand side is the declaration and -initialization of a class template that implements a @emph{smart pointer}. - -@verbatim - Ptr p = ... -@end verbatim - -To a first approximation, you can think of @code{Ptr} as the a new kind -of declaration of a pointer to a @code{Node} object. The difference is that -a smart pointer is a user-defined data type (instantiated via a templated -class) that @emph{simulates} a classical pointer but provides additional -features. As an aside, you typically pronounce @code{Ptr} as -``pooter node'' where pooter rhymes with footer. - -@cindex memory management -One of the most important ``additional feature'' provided by smart pointers is -automatic memory management. Since you now understand class templates, you -will understand how the template allows us to write the pointer code once, but -allows us to point to many different kinds of objects. Later in the tutorial -you will see variations such as @code{Ptr} and @code{Ptr}, -which are smart pointers to an IP version 4 object and a channel object, -respectively. - -The use of built-in pointers in C and C++ is a major source of bugs. Constant -allocation of, passing of responsibility for, and deallocation of underlying -data makes it very likely that errors will occur. In one of these errors, -the usual problem is that the responsibility for deallocating a memory block -is misplaced. This may result in a memory leak or a duplicate deallocation. -Smart pointers try to prevent this kind of problem by working with the -@emph{scope} and @emph{extent} rules of the language to make memory -deallocation automatic. - -The scope of a variable defines where in a program a given variable may be -referred to. The extent of a variable defines when in the program's execution -the variable has a valid value. Consider a simple subroutine that contains a -smart pointer. - -@verbatim - void SimpleSubroutine (void) - { - Ptr p; - } -@end verbatim - -@cindex scope -The variable named @code{p} has a scope limited to the subroutine itself. The -variable is said to @emph{come into scope} as the subroutine is entered during -execution. At this time, the constructor of the underlying class is executed -and a valid variable is available for use. When the subroutine is done -executing, the variable is said to @emph{go out of scope}. This causes the -destructor of the underlying class to be executed and the variable no longer -has a valid value. This is not a problem since it is no longer valid to refer -to the parameter. Smart pointers take advantage of these defined actions at -points where variables must be valid and become discardable to determine when -underlying data can be freed. - -@cindex reference counting!intrusive -The ns-3 smart pointer mechanism uses a mechanism called intrusive -reference counting to determine when a memory block should be automatically -deallocated. The term ``intrusive'' means that a reference count (a count of -variables required to have valid data) is stored in the object being managed -instead of in a proxy object. This means that each piece of memory managed by -a ns-3 smart pointer includes a reference count. When a smart -pointer to a reference counted object is created, this reference count is -incremented. This indicates that a new variable requires a valid data object -be present. When a smart pointer to a reference counted object is destroyed -(for example, when going out of scope) the reference count of the managed -object is decremented. When the reference count goes to zero it means that -all smart pointers to the underlying object have gone out of scope and the -object is no longer needed by any past ``users'' of the object. This in turn -means that the object can be safely deallocated, and this is done -automatically for you as the ``last'' smart pointer goes out of scope. - -Consider how this might work as you pass a smart pointer to an object down -a protocol stack. At each level of the stack, you pass the smart pointer -by value. This causes a copy of the smart pointer to be made, which -increments the reference count of the underlying object. When the -@emph{calling} method is done executing, the calling smart pointer goes out of -scope and the reference count is decremented. This leaves the single smart -pointer in the @emph{called} method with a reference to the underlying object. -When the smart pointer in the called method goes out of scope, the destructor -for the smart pointer is called. The destructor checks the reference count -of the underlying object and sees that it becomes zero. This indicates that -the object can be deallocated, and the destructor does so. This results in -the lifetime management of the underlying object being automatically managed, -a boon if you have experience with ``manual'' memory management and finding -memory leaks. - -Now, we want to make this feature available as widely as possible to objects -in the ns-3 system. The basic operations of the smart pointer class -are the same across any intrusively reference counted object. C++ provides a -mechanism to achieve this kind of generic behavior --- the template. Let's -examine the declaration of the smart pointer in more detail. First consider -the way you might declare and use a built-in pointer. For the sake of -simplicity, just assume that a C++ object of the class @code{MyClass} exists. -Further assume that @code{MyClass} provides one method called @code{method}. -Using built-in pointers, you could do something like the following: - -@verbatim - MyClass *p = ... - p->method (); -@end verbatim - -@cindex smart pointer -One of the key design points of smart pointers is that they should simulate -built-in pointers. In C++ this is done by overloading @code{operator->}, -@code{operator=} and @code{operator*}. To implement a smart pointer we need -to provide a generic class that implements these operators. This generic -class should allow operations that appear as if it were a built-in pointer -to the reference counted object. Typically this is accomplished via a -relatively simple C++ class template. If you are interested in the details -of how this may be accomplished, see Alexandrescu for a good treatment, - -@cindex template -Taking the template as given, in order to declare a smart pointer you will -need to create a smart pointer object and provide the template parameter -needed to instantiate the required code. This parameter will be the name -of the reference counted class to which you want to point. The smart -pointer class overrides @code{operator=} which allows initialization of the -smart pointer just as if it were a built-in pointer. The end result is that -you use smart pointers just as if they were built-in pointers: - -@verbatim - SmartPointer p = ... - p->method (); -@end verbatim - -@node Object Creation -@subsection Object Creation -@cindex CreateObject -On the right hand side of the line of code we're examining (reproduced below -for convenience) is the creation of an @code{InternetNode} object. - -@verbatim - ... = CreateObject (); -@end verbatim - -@cindex template!function -This turns out to be an instance of use of a C++ @emph{function template}. The -definition of the @code{CreateObject()} template calls the new -operator to create an object of the type T. It then creates a new smart -pointer of the appropriate type (i.e., @code{Ptr}). This new smart -pointer is assigned initial responsibility for the new object which has its -reference count set to one. - -Since the underlying creation mechanism is via the @code{new} operator, and -you can pass parameters to the constructor for an object, we provide several -templates that you can use for passing parameters to the object constructors. -If the constructor for the object requires a parameter, you simply pass that -parameter to the @code{Create} function like this, - -@verbatim - int parm = 1; - ... = CreateObject (parm); -@end verbatim - -We provide Create templates with up to seven parameters, so you could -conceivably use the @code{Create} template in situations such as, - -@verbatim - int parm = 1; - ... = CreateObject (p1, p2, p3, p4, p5, p6, p7); -@end verbatim - -@subsection Type Safety -Lets take one final look at the now infamous example line of code that we -have been examining for some time (again reproduced below). - -@verbatim - Ptr p = CreateObject (); -@end verbatim - -@cindex smart pointer -@cindex Node -@cindex Create -You may have noticed that the smart pointer on the left hand side of the -assignment is associated with the type @code{Node} and the @code{Create} -template on the right hand side creates an @code{InternetNode} object and -returns a @code{Ptr} smart pointer. For this assignment of a -@code{Ptr} to a @code{Ptr} to work, there must be some -kind of type conversion going on. - -@cindex implicit conversion -Many programmers use @code{implicit conversions} without even realizing it -since they are sometimes so intuitive. For example, in the following code, - -@verbatim - int i = 1; - double d = 2.; - if (n == d) ... -@end verbatim - -@cindex standard conversion -the integer (1) is implicitly converted to a double (1.) before the comparison -takes place. This conversion is performed using what is known as a C++ -@emph{standard conversion}. There are a number of standard conversions defined -by the C++ standard. Among them are, - -@itemize @bullet -@item Integral Promotions -@item Integral Conversions -@item Floating Conversions -@item Pointer Conversions -@item Reference Conversions -@end itemize - -@cindex assignment operator -@cindex Ptr -For the case of interest here, we need to know what happens in the -assignment operator (@code{operator=}) of our smart pointer @code{Ptr}. -This operator takes a reference to a @code{Ptr} and not a reference to -a @code{Ptr}. The one situation where this works automatically -in C++ is if the ``destination'' reference is to a visible, unambiguous base -class of the ``source'' reference. In this case, the underlying pointer is -@emph{cast} from one type to the other automatically. - -To summarize: The magic happens in the assignment operator. Class -@code{InternetNode} inherits from class @code{Node}. The reference to the -@code{InternetNode} object in question is, in essence, a pointer to an -@code{InternetNode} object. The @code{InternetNode} class inherits from the -@code{Node} base class in a way that makes @code{Node} visible and unambiguous. -Therefore, there exists a standard conversion from an @code{InternetNode *} -to a @code{Node *} and by extension from an @code{InternetNode &} to a -@code{Node &}. This conversion is applied automatically (and invisibly) -during parameter passing in the assignment operator we are examining. - -@cindex base class -This is a rather involved way of saying there's an invisible pointer cast -to a base class happening in the assignment. That means that - -@verbatim - Ptr p = CreateObject (); -@end verbatim - -or, - -@verbatim - Ptr p = CreateObject (); -@end verbatim - -will work just fine. Of course, if you try something @emph{bad} (TM), like: - -@verbatim - Ptr p = CreateObject (); -@end verbatim - -the compiler will quite appropriately complain that there is no conversion -between these completely unrelated objects (CsmaChannel and Node). - -@subsection Summary -Going back to our infamous first line of ns-3 code, we said that if -we want to create an InternetNode in a script, we will typically do something -like: - -@verbatim - Ptr p = CreateObject (); -@end verbatim - -@cindex Create -@cindex InternetNode -@cindex smart pointer -Now we know that this is really a simple statement. We create an -@code{InternetNode} object on the heap (indirectly using operator @code{new} -and passing no parameters to its constructor) and assign responsibility for -managing the new object's lifetime to a smart pointer. This smart pointer is -a pointer to a @code{Node} object, so there was a hidden cast from -@code{InternetNode} to a @code{Node} done via a standard C++ conversion. - -This may have been quite a hurdle to get past that first line of code, but -we have covered quite a few of the important idioms that you'll encounter in -this tutorial. - -@c ======================================================================== -@c A First ns-3 script -@c ======================================================================== - -@node A-First-ns-3-Script -@chapter A First ns-3 script -@cindex design pattern -@cindex idiom -Lets build a simple network using the ns-3 design patterns, idioms, -classes and helpers we have just looked at. If you downloaded the system as -was suggested above, you will have a release of ns-3 in a directory -called @code{repos} under your home directory. Change into that directory, -where you should see a directory structure something like the following. - -@verbatim - AUTHORS RELEASE_NOTES examples/ src/ waf* - LICENSE VERSION ns3/ tutorial/ waf.bat* - README doc/ samples/ utils/ wscript -@end verbatim - -@cindex hello-simulator.cc -Change into the tutorial directory. You should see a file named -@code{hello-simulator.cc} located there. Copy this file into one named -@code{simple.cc}. If you open this new file in your favorite editor you will -see some copyright information and the following C++ code: - -@verbatim - #include "ns3/log.h" - - NS_LOG_COMPONENT_DEFINE ("HelloSimulator"); - - using namespace ns3; - - int - main (int argc, char *argv[]) - { - LogComponentEnable ("HelloSimulator", LOG_LEVEL_INFO); - - NS_LOG_INFO ("Hello Simulator"); - } -@end verbatim - -This is the ns-3 version of the ubiquitous hello-world program. It -uses the ns-3 Log module to print ``Hello Simulator'' into the - standard error output stream. - -@cindex logging -Log components are named objects that provide for controlling the verbosity of -debugging output in the system. We'll have a lot more to say about logging -later on, but for now you can just consider the macro @code{NS_LOG_INFO} to be -a kind of fancy printf to the standard error. - -@section A Simple Network -@cindex InternetNode -Let's create a simple network of @code{InternetNode} elements. In order to -actually create an @code{InternetNode}, you will have to include some header -files. Put the following code after the include statement in @code{simple.cc}. - -@verbatim - #include "ns3/ptr.h" - #include "ns3/internet-stack.h" -@end verbatim - -@cindex include files -The ns-3 build system places the core include files it needs into a -directory called @code{ns-3} and so whenever you need to include one of the -core files you need to explicitly code this. The file @code{ptr.h} defines -the generic smart pointer that we use. The file @code{internet-stack.h} -defines the class InternetNode which, as described above, represents an IP -version 4-based computing element in the simulator. - -So let's create a few new @code{InternetNode}s by adding the following lines -of code after the call to @code{NS_LOG_INFO} in the simple.cc file right -after the call to @code{NS_LOG_INFO}. - -@verbatim - Ptr n0 = CreateObject (); - Ptr n1 = CreateObject (); - Ptr n2 = CreateObject (); - Ptr n3 = CreateObject (); -@end verbatim - -As we now understand, this will create four @code{InternetNode} objects on -the heap and create four @code{Ptr} smart pointer objects on the stack -to manage them. You should remember that by using the smart pointers you are -freed from the responsibility to delete the objects you assign to them. - -@cindex Channel -@cindex CsmaChannel -The next step is to create a channel over which these nodes can communicate. -Let's use the CsmaChannel and create a local area network that will allow us -to hook up nodes similarly to an Ethernet. - -As usual, we'll need to include the file that provides the appropriate class -declarations: - -@verbatim - #include "ns3/csma-channel.h" -@end verbatim - -Next, Add the following line of code (typically done after node creation) to -create a channel with a five megabit per second data rate and a two -millisecond speed-of-light delay between all nodes. The idiom for creating -the channel is similar to that of the node, but the actual @code{Create} -function is hidden from us in the topology code. Observe that we are -using a Csma topology helper function to free us from the details regarding -how the Carrier Sense Multiple Access Channel is actually brought into -existence and initialized. - -@verbatim - Ptr lan = - CsmaTopology::CreateCsmaChannel (DataRate (5000000), MilliSeconds (2)); -@end verbatim - -@cindex idiom!unnamed parameter -You may be unfamiliar with the @emph{unnamed parameter} idiom used here. -When added to a list of parameters, the code @code{DataRate (5000000)} -constructs a DataRate object on the stack using the appropriate constructor. -The resulting object has no name, and therefore cannot be referenced -elsewhere, but is passed to the callee method where it has a valid name and -can be used. This idiom is essentially a shorthand version of the following: - -@verbatim - DataRate rate (5000000); - Time latency (MilliSeconds (2)); - Ptr lan = CsmaTopology::CreateCsmaChannel (rate, latency); -@end verbatim - -@cindex constructor -@cindex constructor!Time -We should pause for a moment and discuss the constructor to the @code{Time} -data type. There are a number of different constructors for these objects, and -so there are a number of ways that this initialization could have been done. -There is a constructor that takes a string argument, consisting of expressions -using the units @code{s, ms, us, ns, ps} or @code{fs}, so this could have been -written, - -@verbatim - Time latency ("2ms"); -@end verbatim - -There are also helper functions available that create time units (one of these -was used in the example): - -@itemize @bullet -@item @code{Seconds (double)} -@item @code{MilliSeconds (uint64_t)} -@item @code{MicroSeconds (uint64_t)} -@item @code{NanoSeconds (uint64_t)} -@item @code{PicoSeconds (uint64_t)} -@item @code{FemtoSeconds (uint64_t)} -@end itemize - -C++ will attempt to promote parameters appropriately, but you will typically -see constructions that respect the type correctness of the constructor, as -in @code{Seconds (1.)} and @code{MilliSeconds (2)}. Notice that the code -@code{Seconds (1)} will work just as well as @code{Seconds (1.)} since the -integer 1 will be automatically promoted to a double 1. in the former code. -The converse will not work --- i.e., you cannot write code that says -@code{MilliSeconds (2.)} since a @emph{type demotion} would be required that -could lose information and the compiler will not do such things ``behind your -back.'' Don't be thrown off by this kind of automatic conversion. - -@cindex MAC!address -Okay, now we have code to create four nodes and a local area network. The -next step is to wire the network together. We do this by adding net devices -to the node. When we add the net device, we also specify the network to which -the net device is connected and provide a MAC address appropriate to the -device and network types. Since we're creating an IP version 4 network using -a Csma channel, you may expect that we'll be using topology helpers -appropriate to those types --- the CsmaIpv4Topology helper. As you may expect, -we'll need to include some files to get the appropriate definitions: - -@verbatim - #include "ns3/mac48-address.h" - #include "ns3/csma-net-device.h" - #include "ns3/csma-topology.h" - #include "ns3/csma-ipv4-topology.h" -@end verbatim - -Now, all that is left is to do the ``wiring'': - -@verbatim - uint32_t nd0 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n0, lan, - Mac48Address("08:00:2e:00:00:00")); -@end verbatim - -[Note the additional unnamed parameter idiom usage here.] - -This code calls the topology helper relating to Csma channels and IP version -four nodes. It asks to install a Csma net device ``into'' node zero -(@code{n0}) connecting the device to the channel named (@code{lan}). It also -assigns a MAC address to the net device. You can add similar lines of code -connecting the other nodes to the lan (remembering to assign new MAC -addresses). - -@verbatim - uint32_t nd1 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n1, lan, - Mac48Address("08:00:2e:00:00:01")); - - uint32_t nd2 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n2, lan, - Mac48Address("08:00:2e:00:00:02")); - - uint32_t nd3 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n3, lan, - Mac48Address("08:00:2e:00:00:03")); -@end verbatim - -@cindex IP!address -@cindex IP!network mask -@cindex multihome -Finally, we need to add IP addresses to our nodes. The pointers to the -nodes are stored in n0, n1, n2 and n3. We added net devices to each of -the nodes and remembered the net device index numbers as nd0, nd1, nd2 and -nd3. You can add multiple net devices to each node resulting in a situation -similar to a multi-homed host. Each time you add a net device, you will get -a new index. Since the IP address for a multi-homed host is associated with -a net device, we need to provide that index (which we have saved) to the -topology helper. We provide an IP version four address via the ns-3 -class @code{Ipv4Address} which takes a dotted decimal string as a constructor -parameter. We also provide a network mask using the ns-3 class -@code{Ipv4Mask} which also takes a dotted decimal string. The code to -perform the IP address assignment, then, looks like the following: - -@verbatim - CsmaIpv4Topology::AddIpv4Address (n0, nd0, Ipv4Address ("10.1.1.1"), - Ipv4Mask ("255.255.255.0")); - - CsmaIpv4Topology::AddIpv4Address (n1, nd1, Ipv4Address ("10.1.1.2"), - Ipv4Mask ("255.255.255.0")); - - CsmaIpv4Topology::AddIpv4Address (n2, nd2, Ipv4Address ("10.1.1.3"), - Ipv4Mask ("255.255.255.0")); - - CsmaIpv4Topology::AddIpv4Address (n3, nd3, Ipv4Address ("10.1.1.4"), - Ipv4Mask ("255.255.255.0")); -@end verbatim - -We have now constructed a simulated network. Your code should now look -something like the following, - -@verbatim - #include "ns3/log.h" - #include "ns3/ptr.h" - #include "ns3/internet-stack.h" - #include "ns3/csma-channel.h" - #include "ns3/mac48-address.h" - #include "ns3/csma-net-device.h" - #include "ns3/csma-topology.h" - #include "ns3/csma-ipv4-topology.h" - - NS_LOG_COMPONENT_DEFINE ("HelloSimulator"); - - using namespace ns3; - - int - main (int argc, char *argv[]) - { - LogComponentEnable ("HelloSimulator", LOG_LEVEL_INFO); - - NS_LOG_INFO ("Hello Simulator"); - - Ptr n0 = CreateObject (); - Ptr n1 = CreateObject (); - Ptr n2 = CreateObject (); - Ptr n3 = CreateObject (); - - Ptr lan = - CsmaTopology::CreateCsmaChannel (DataRate (5000000), MilliSeconds (2)); - - uint32_t nd0 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n0, lan, - Mac48Address("08:00:2e:00:00:00")); - - uint32_t nd1 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n1, lan, - Mac48Address("08:00:2e:00:00:01")); - - uint32_t nd2 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n2, lan, - Mac48Address("08:00:2e:00:00:02")); - - uint32_t nd3 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n3, lan, - Mac48Address("08:00:2e:00:00:03")); - - CsmaIpv4Topology::AddIpv4Address (n0, nd0, Ipv4Address ("10.1.1.1"), - Ipv4Mask ("255.255.255.0")); - - CsmaIpv4Topology::AddIpv4Address (n1, nd1, Ipv4Address ("10.1.1.2"), - Ipv4Mask ("255.255.255.0")); - - CsmaIpv4Topology::AddIpv4Address (n2, nd2, Ipv4Address ("10.1.1.3"), - Ipv4Mask ("255.255.255.0")); - - CsmaIpv4Topology::AddIpv4Address (n3, nd3, Ipv4Address ("10.1.1.4"), - Ipv4Mask ("255.255.255.0")); - } -@end verbatim - -This script won't actually do anything yet. The next trick will be to -convince our nodes to try and send some data over the network. - -@section Using Applications -@cindex Create -As mentioned above, we use @code{Application}s in ns-3 to generate -the data used to drive simulations. An @code{Application} is added to a -ns-3 node conceptually just as if you would add an application to a -computer. When an application is created (using the @code{Create} template) -we tell the application which @code{Node} it belongs to (and therefore on -which node it is running) by passing a smart pointer to that @code{Node} in -the constructor arguments. - -@subsection A UDP Echo Client Application -To use an application, we first have to load the header file in which it is -defined. For the UDP echo client, this would mean adding the line, - -@verbatim -#include "ns3/udp-echo-client.h" -@end verbatim - -In order to create the UDP echo client application we will need to add the -following code: - -@verbatim - uint32_t packetSize = 1024; - uint16_t port = 7; - uint32_t maxPacketCount = 1; - Time interPacketInterval = Seconds (1.); - - Ptr client = CreateObject (n0, "10.1.1.2", - port, maxPacketCount, interPacketInterval, packetSize); -@end verbatim - -@cindex packet -The first four lines have broken out the configuration parameters for the -application as named parameters for clarity. We are telling the application -to generate 1024 byte packets (@code{packetSize = 1024}); and to send these -packets to port 7 (@code{port = 7;}). The application is told to send at most -one packet (@code{maxPacketCount = 1;}); and to delay for one second between -packet sends (@code{interPacketInterval = Seconds(1.)}) which is not used since -only one packet is sent. We will defer addressing the type @code{Time} until -we discuss the simulator engine. For now just understand the semantics are -to wait for one second. - -The code to actually create the @code{UdpEchoClient} application uses the -same creation idiom as we have used previously. Notice that we have a case -where the @code{Create} template is used to pass parameters to the constructor -of the underlying object. - -@cindex implicit conversion sequence -Notice that a string is passed as the second parameter. The formal parameter -to the constructor of the @code{UdpEchoClient} object is actually an -@code{Ipv4Address}. We get away with this since C++ allows what are called -@emph{implicit conversion sequences} to occur between the argument in the -function call and the corresponding parameter in the function declaration. -Basically, C++ will try to figure out a way to convert parameters for you -transparently. - -In this case the conversion sequence is based on the constructor for the -Ipv4Address that takes a @code{char const *} as a parameter. C++ notices -that @code{"10.1.1.2"} refers to a @code{char const *} and knows that it -needs to get from there to an @code{Ipv4Address}. The compiler notices that -there is an @code{Ipv4Address} constructor that takes a @code{char const *} -and so it uses that constructor transparently to arrange for the conversion. - -You therefore have several options for passing this value. You can use an -explicit named variable as in the following: - -@verbatim - Ipv4Address addr ("10.1.1.2"); - ... - - Ptr client = CreateObject (n0, addr, port, - maxPacketCount, interPacketInterval, packetSize); -@end verbatim - -@cindex idiom|unnamed parameter -You can use the unnamed parameter idiom that we have previously seen: - -@verbatim - Ptr client = CreateObject (n0, - Ipv4Address ("10.1.1.2"), port, maxPacketCount, interPacketInterval, - packetSize); -@end verbatim - -Or you can rely on implicit conversion sequences as we just saw: - -@verbatim - Ptr client = CreateObject (n0, "10.1.1.2", - port, maxPacketCount, interPacketInterval, packetSize); -@end verbatim - -Which approach to take is a matter of style, really, and you will probably -see all three approaches taken in the ns-3 code. You should be -comfortable seeing and using all three methods. - -@subsection A UDP Echo Server Application -As usual, to use the UDP echo server we need to add a line to define the -application: - -@verbatim -#include "ns3/udp-echo-server.h" -@end verbatim - -In order to create the UDP echo server application we will need to add the -following code: - -@verbatim - Ptr server = CreateObject (n1, port); -@end verbatim - -We only need to tell the application which node to reside on and which port -to listen on for UDP packets. The code to actually create the -@code{UdpEchoServer} application uses the now quite familiar ns-3 object -creation idiom. - -@subsection A UDP Echo Client-Server Simulation -Now we're getting somewhere. Your code should look something like the -following (let's change the log component name and program banner from -``Hello Simulator''to something more descriptive while we're at it). - -@verbatim - #include "ns3/log.h" - #include "ns3/ptr.h" - #include "ns3/internet-stack.h" - #include "ns3/csma-channel.h" - #include "ns3/mac48-address.h" - #include "ns3/csma-net-device.h" - #include "ns3/csma-topology.h" - #include "ns3/csma-ipv4-topology.h" - #include "ns3/udp-echo-client.h" - #include "ns3/udp-echo-server.h" - - NS_LOG_COMPONENT_DEFINE ("UdpEchoSimulation"); - - using namespace ns3; - - int - main (int argc, char *argv[]) - { - LogComponentEnable ("UdpEchoSimulation", LOG_LEVEL_INFO); - - NS_LOG_INFO ("UDP Echo Simulation"); - - Ptr n0 = CreateObject (); - Ptr n1 = CreateObject (); - Ptr n2 = CreateObject (); - Ptr n3 = CreateObject (); - - Ptr lan = - CsmaTopology::CreateCsmaChannel (DataRate (5000000), MilliSeconds (2)); - - uint32_t nd0 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n0, lan, - Mac48Address("08:00:2e:00:00:00")); - - uint32_t nd1 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n1, lan, - Mac48Address("08:00:2e:00:00:01")); - - uint32_t nd2 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n2, lan, - Mac48Address("08:00:2e:00:00:02")); - - uint32_t nd3 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n3, lan, - Mac48Address("08:00:2e:00:00:03")); - - CsmaIpv4Topology::AddIpv4Address (n0, nd0, Ipv4Address ("10.1.1.1"), - Ipv4Mask ("255.255.255.0")); - - CsmaIpv4Topology::AddIpv4Address (n1, nd1, Ipv4Address ("10.1.1.2"), - Ipv4Mask ("255.255.255.0")); - - CsmaIpv4Topology::AddIpv4Address (n2, nd2, Ipv4Address ("10.1.1.3"), - Ipv4Mask ("255.255.255.0")); - - CsmaIpv4Topology::AddIpv4Address (n3, nd3, Ipv4Address ("10.1.1.4"), - Ipv4Mask ("255.255.255.0")); - - uint32_t packetSize = 1024; - uint16_t port = 7; - uint32_t maxPacketCount = 1; - Time interPacketInterval = Seconds (1.); - - Ptr client = CreateObject (n0, "10.1.1.2", - port, maxPacketCount, interPacketInterval, packetSize); - - Ptr server = CreateObject (n1, port); - - } -@end verbatim - -@section Using the Simulation Engine -@cindex model -@cindex simulation executive -You could say that the heart of the ns-3 system is the -@emph{simulation engine} (sometimes called the simulation executive in other -systems). - -In a computer simulation, a computer @emph{model} of a real world @emph{system} -is constructed. This is typically done to minimize cost since you do not have -to actually buy, install and maintain physical hardware. In the case of -ns-3, a model is a representation of a networking component that is -designed to imitate some number of important behaviors or characteristics of -an actual component in a real network. A system is a collection of models -arranged for the purpose of analyzing some behavior. - -@section Models -@cindex CsmaNetDevice -@cindex CsmaChannel -@cindex InternetNode -@cindex NIC -@cindex CSMA -We have already encountered several ns-3 models without specifically -calling them so. The @code{InternetNode}, @code{CsmaNetDevice} and -@code{CsmaChannel} objects are models of an Internet computing node, a CSMA -network interface card (NIC), and a network cable able to move data to and -from other CSMA NICs. - -@cindex model -@cindex CSMA/CD -It is important to note that the @code{Csma} net devices and the @code{Csma} -channel do not correspond to any real world hardware that you can actually go -out and buy. These models implement an approximation, or subset, of the -behaviors that a real CSMA/CD network would have. In this case, the -@code{CsmaNetDevice} does not simulate collision detection (CD). It does -implement carrier sense and performs collision @emph{avoidance} using global -spatial knowledge available in the channel. This would be impossible in any -channel residing in our universe. - -@cindex Ethernet -No model will fully implement @emph{all} of the behaviors of a piece of -hardware. It is important to understand what is being modeled by the -ns-3 components you are using and what is not. For example, the Csma -components we use in this tutorial model a highly abstract multiple access -network that is topologically equivalent to an Ethernet. It is not necessarily -true that results found in a simulation using the Csma models will apply to -a real-world Ethernet network. You must understand what behaviors are -simulated in each of the models before trusting that any results can be -associated with real-world systems. - -@section Time, Events and Callbacks -@cindex time -@cindex event -In a @emph{discrete event simulator} time is not something that @emph{flows}, -nor is it something to be measured --- it is the driving force behind the -progress of the simulation. Time is progressed forward by the simulation -engine and anything that happens in the simulation is ultimately caused by -an @emph{event}. An event is some action in the system that is -@emph{scheduled} to happen at a certain time by the simulation engine. Time -does not flow continuously but steps discretely (in possibly large jumps) -from one scheduled event to another. - -@cindex packet -For example, to start the flow of a packet through the system, one would have -to schedule an event with the simulation engine @emph{before} the simulation -was started. This is important since the simulation engine only jumps time -forward if there is a next event to process. The simulation stops if there -are no more events, which is equivalent to a state where there is ``nothing -more to do.'' Before the simulation starts, one schedules driving events in -terms of absolute time. For example, one could schedule an event to start -the flow of a first packet at, say, ten simulated seconds. In this case, the -simulation would start its clock at zero seconds and look for the first event -in its @emph{event queue}. It would immediately jump time forward by ten -seconds and @emph{fire} the scheduled event --- that is, make the event happen. - -@cindex functor -@cindex function object -@cindex callback -@cindex Callback -In ns-3 an event is basically a pre-packaged function call called a -@emph{functor}. Functors are also known as @emph{function objects}, which is -a more descriptive term --- an object (in the object-oriented programming -sense) that can be called as if it was a function. Typically one uses a -functor to implement @emph{deferred execution} of a function or method. The -most commonly encountered form of deferred execution is in a @emph{callback} -from an I/O system. In this case, the goal would be to start an I/O -operation and return immediately, without having to wait for the operation -to complete. One asks the I/O subsystem to notify you when an operation is -complete by calling some function you provide. This provided function is -known as a callback function. [Imagine calling someone on the telephone and -asking them to do something for you. You also ask them to @emph{call you back} -when they are done.] Events in the ns-3 system work conceptually -the same way, except that instead of an I/O completion driving the process, -the arrival of some simulated time drives the process. The ns-3 -deferred execution mechanism is via a class called @code{Callback}. - -@cindex Time -@cindex Callback -The internal details of the classes representing @code{Time} and -@code{Callback} abstractions will be introduced as required. We won't see -events directly for some time, but you should know that they are happening -``under the sheets'' of the simulations you will be writing. - -@section Driving the Simulation -@cindex Application -As mentioned previously, time is the driving force behind the progress of -a ns-3 simulation. Events are scheduled to happen at certain times -by calling methods of the simulation engine, either directly or indirectly -through, for example, an @code{Application}. - -In order to get the simulation engine set up and running in our code, we must -first include the language definitions required to describe time- and -simulator-specific classes: - -@verbatim - #include "ns3/simulator.h" - #include "ns3/nstime.h" -@end verbatim - -@cindex Application -As we have seen, we need to ``seed'' the simulation with at least one event. -In the case of an @code{Application}, a method to do this is provided. This -method must be implemented by each specialization of the class and we must -call this method in our script before the simulation starts. We can also -provide an event (indirectly) to stop the output of the application at a -certain time. This is done by adding the following lines to our script: - -@verbatim - server->Start(Seconds(1.)); - client->Start(Seconds(2.)); - - server->Stop (Seconds(10.)); - client->Stop (Seconds(10.)); -@end verbatim - -@cindex Application -@cindex time -@cindex Time -@cindex socket -@cindex event -In the case of the UdpEchoServer, the call to @code{server->Start ()} gives -the @code{Application} the chance to schedule an event that will perform the -usual @emph{sockets} server sequence of socket creation, binding and -recvfrom (see Donahoo's UDPEchoServer.c). - -In the case of the UdpEchoClient, the call to @code{client->Start ()} gives -the @code{Application} the chance to schedule an event that will perform the -usual @emph{sockets} client sequence of socket creation, sendto and recvfrom -(see Donahoo's UDPEchoClient.c). - -@cindex event -Note that the start event for the server is scheduled to happen before the -start event of the client, just as you would start a server application before -you would attempt to start a client application in the real world. - -@cindex socket!sendto -The ns-3 equivalent of the call to @code{sendo} in the client will -schedule (immediately) the transmission of a UDP packet over the just created -socket. This will cause the packet to percolate down the protocol stack and -eventually into the channel. The channel will schedule a reception event in -the net device on the destination node. This event will eventually percolate -up into the server application. The server application will create a reply -packet and send it back down its stack and eventually back to the channel. -The channel will schedule a reception event back in the client and this will -cause the reply to be sent back up the protocol stack to the client -application. - -The calls to @code{Stop ()} for both applications cause the sockets to be -torn down and therefore the sending and receiving of packets will be stopped -irrespective of other application settings (such as max packets and interval -in the client). - -Finally, we need to run the simulation and when the simulation run is complete, -clean up any resources allocated during the run. This is done by the calling -the following static methods: - -@verbatim - Simulator::Run (); - Simulator::Destroy (); -@end verbatim - -We now have the makings of a complete ns-3 network simulation. The -source code for the script should look like the following: - -@verbatim - #include "ns3/log.h" - #include "ns3/ptr.h" - #include "ns3/internet-stack.h" - #include "ns3/csma-channel.h" - #include "ns3/mac48-address.h" - #include "ns3/csma-net-device.h" - #include "ns3/csma-topology.h" - #include "ns3/csma-topology.h" - #include "ns3/csma-ipv4-topology.h" - #include "ns3/udp-echo-client.h" - #include "ns3/udp-echo-server.h" - #include "ns3/simulator.h" - #include "ns3/nstime.h" - - NS_LOG_COMPONENT_DEFINE ("UdpEchoSimulation"); - - using namespace ns3; - - int - main (int argc, char *argv[]) - { - LogComponentEnable ("UdpEchoSimulation", LOG_LEVEL_INFO); - - NS_LOG_INFO ("UDP Echo Simulation"); - - Ptr n0 = CreateObject (); - Ptr n1 = CreateObject (); - Ptr n2 = CreateObject (); - Ptr n3 = CreateObject (); - - Ptr lan = - CsmaTopology::CreateCsmaChannel (DataRate (5000000), MilliSeconds (2)); - - uint32_t nd0 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n0, lan, - Mac48Address("08:00:2e:00:00:00")); - - uint32_t nd1 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n1, lan, - Mac48Address("08:00:2e:00:00:01")); - - uint32_t nd2 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n2, lan, - Mac48Address("08:00:2e:00:00:02")); - - uint32_t nd3 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n3, lan, - Mac48Address("08:00:2e:00:00:03")); - - CsmaIpv4Topology::AddIpv4Address (n0, nd0, Ipv4Address ("10.1.1.1"), - Ipv4Mask ("255.255.255.0")); - - CsmaIpv4Topology::AddIpv4Address (n1, nd1, Ipv4Address ("10.1.1.2"), - Ipv4Mask ("255.255.255.0")); - - CsmaIpv4Topology::AddIpv4Address (n2, nd2, Ipv4Address ("10.1.1.3"), - Ipv4Mask ("255.255.255.0")); - - CsmaIpv4Topology::AddIpv4Address (n3, nd3, Ipv4Address ("10.1.1.4"), - Ipv4Mask ("255.255.255.0")); - - uint32_t packetSize = 1024; - uint16_t port = 7; - uint32_t maxPacketCount = 1; - Time interPacketInterval = Seconds (1.); - - Ptr client = CreateObject (n0, "10.1.1.2", - port, maxPacketCount, interPacketInterval, packetSize); - - Ptr server = CreateObject (n1, port); - - server->Start(Seconds(1.)); - client->Start(Seconds(2.)); - - server->Stop (Seconds(10.)); - client->Stop (Seconds(10.)); - - Simulator::Run (); - Simulator::Destroy (); - } -@end verbatim - -@cindex tutorial-csma-echo.cc -Just to make sure you don't get caught up in debugging typographical errors -we have provided this source code for you (along with a copyright header) in -the @code{tutorial} subdirectory of the ns-3 distribution as -@code{tutorial-csma-echo.cc}. We used this opportunity to do some ``clean up'' -of some of our example cases by passing parameters using implicit conversion -sequences and removing some of the named parameters. [These were used for -pedagogic purposes and were not actually necessary.] - -@section Building the Script -@cindex Waf -C++ is a compiled language, so you know it had to happen. We have to build -the script before we run it. As mentioned before, we use the Waf build system -which is Python-based. We have to change gears slightly and switch ourselves -to Python mode in order to proceed. - -In each subdirectory of the ns-3 distribution in which there are -source files, you will find two files: one will be named @code{waf} and one -will be named @code{wscript}. The former, @code{waf}, is a link that allows -one to start the build process from any subdirectory. We can ignore that one. -The file we need to deal with is @code{wscript}. - -@cindex wscript -Open the file @code{ns-3-dev/tutorial/wscript} in your favorite editor -[remember I'm assuming that you have the distribution saved in a -repository under a directory called @code{repos} in you home directory.] - -@cindex Python -You should see the following Python code (after an emacs mode line). - -@verbatim - def build(bld): - obj = bld.create_ns3_program('hello-simulator') - obj.source = 'hello-simulator.cc' -@end verbatim - -These are the only instructions required to build a simulation (I told you -it wasn't going to be too bad). The line with the method -@code{bld.create_ns3_program} tells the build system to create an object -file that is a program (executable) named @code{hello-simulator}. The -following line, with the method @code{obj.source} tells the build system that -the source file for the program is the file @code{hello-simulator.cc'} in the -local directory. The required libraries are linked for you for free. - -All that needed to be done in order to build the new simulation using the new -source file was to copy the two lines describing the @code{hello-simulator} -program and change the names to @code{tutorial-csma-echo}. You can see these -lines in the @code{wscript} file, - -@verbatim - def build(bld): - obj = bld.create_ns3_program('hello-simulator') - obj.source = 'hello-simulator.cc' - - obj = bld.create_ns3_program('tutorial-csma-echo') - obj.source = 'tutorial-csma-echo.cc' - - ... -@end verbatim - -When you built the system above, you actually already built this new -simulation and a number of other examples. Since you have already configured -@code{Waf} and built the @code{tutorial-csma-echo} script, you can run the -simulation in the same way as you ran the @code{hello-simulator} script using -the @code{waf --run} command: - -@verbatim -~/repos/ns-3-dev/tutorial > waf --run tutorial-csma-echo -Entering directory `~/repos/ns-3-dev/build' -Compilation finished successfully -UDP Echo Simulation -~/repos/ns-3-dev/tutorial > -@end verbatim diff --git a/doc/tutorial/in-process/log.texi b/doc/tutorial/in-process/log.texi deleted file mode 100644 index 2f39efe59..000000000 --- a/doc/tutorial/in-process/log.texi +++ /dev/null @@ -1,24 +0,0 @@ -@node Logging -@chapter Logging -@anchor{chap:Logging} - -This chapter is the first in a series of chapters discussing things that -one can do to modify the input or output of existing ns-3 scripts. - -Examples: -@itemize @bullet -@item Enable or disable the generation of log messages, with fine granularity -@item Set default values for configuration values in the system -@item Generate a report of all configuration values used during a simulation -run (not yet implemented) -@item Set or get values of member variables on objects already instantiated -@item Customizing the tracing output of the script -@item Generate statistics on (not yet implemented) -@item Perform a large number of independent runs of the same simulation -@end itemize - -@node Logging Basics -@section Logging Basics - -@node Enabling Log Output -@section Enabling Log Output diff --git a/doc/tutorial/in-process/other.texi b/doc/tutorial/in-process/other.texi deleted file mode 100644 index 1955d93a2..000000000 --- a/doc/tutorial/in-process/other.texi +++ /dev/null @@ -1,2189 +0,0 @@ -@c ======================================================================== -@c Other Network Topologies -@c ======================================================================== - -@node Other-network-topologies -@chapter Other Network Topologies -@cindex topology -@cindex Channel -@cindex NetDevice -@cindex topology!bus -@cindex topology!point-to-point -@cindex PointToPointChannel -@cindex PointToPointNetDevice - -@emph{Network topology} is the study of the arrangement of of the elements -(in @command{ns-3} represented by the classes @code{Channel} and @code{Node}) -of a network. Two fundamental types of physical topologies are the -@emph{point-to-point} and @emph{bus} topologies. We have already been exposed -to the @command{ns-3} channel specialization named @code{CsmaChannel}. This is -a simulation of a bus network. We also provide a simulation of a -point-to-point channel with associated net devices. As described previously, -the associated C++ classes specialize the @command{ns-3} base classes -@code{NetDevice} and @code{Channel} and are called @code{PointToPointNetDevice} -and @code{PointToPointChannel} respectively. - -We will use combinations of these bus and point-to-point topology elements -to show how to create several commonly seen network topologies. - -@section A Point-to-Point Network -We're going to take what might be seen as a step backward and look at a simple -point-to-point network. We will be building the simplest network you can -imagine. A serial link (point to point) between two computers. When you -see this point-to-point network, you can think of an RS-422 (or RS-232 for -you old-timers) cable. This topology is shown below. - -@sp 1 -@center @image{figures/pp,,,,png} - -@cindex CreateObject -@cindex InternetNode -We have provided a file for you in the @code{tutorial} -directory called @code{tutorial-point-to-point.cc}. You should now be -familiar enough with the system to pick out fairly easily what has been -changed. Let's focus on the following lines: - -@verbatim - Ptr n0 = CreateObject (); - Ptr n1 = CreateObject (); - - Ptr link = PointToPointTopology::AddPointToPointLink ( - n0, n1, DataRate (38400), MilliSeconds (20)); - - PointToPointTopology::AddIpv4Addresses (link, n0, "10.1.1.1", - n1, "10.1.1.2"); -@end verbatim - -You can see that we created two @code{InternetNode} objects in the usual way. -Then, instead of creating a @code{CsmaChannel} we create a -@code{PointToPointChannel}. This point-to-point channel, which we call -@code{link}, connects node zero (@code{n0}) and node one (@code{n1}) over a -simulated link that runs at 38400 bits per second and has a 20 millisecond -simulated speed-of-light delay. This call also creates appropriate net devices -and attaches them to nodes zero and one. - -We then add IP addresses to the net devices we just created using the topology -helper @code{AddIpv4Addresses}. Node zero gets the IP address 10.1.1.1 and -node one gets the IP address 10.1.1.2 assigned. - -The alert tutorial user may wonder what the network number or prefix is of -those IP addresses. The point-to-point topology assumes that you want a -@code{/30} subnet and assigns an appropriate net mask for you. It then then -@emph{asserts} that the network numbers of the two net devices match. So there -is an implicit network mask created down in the topology code that looks like, - -@verbatim - Ipv4Mask netmask("255.255.255.252"); -@end verbatim - -The rest of the code you should recognize and understand. We are just going -to echo one packet across the point-to-point link. You should be now be able -to build and run this example and to locate and interpret the ASCII trace -file. This is left as an exercise for you. - -The file @code{tutorial-point-to-point.cc} is reproduced here for your -convenience: - -@verbatim -/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */ -/* - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License version 2 as - * published by the Free Software Foundation; - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA - */ - -#include "ns3/log.h" -#include "ns3/ptr.h" -#include "ns3/internet-stack.h" -#include "ns3/point-to-point-channel.h" -#include "ns3/mac48-address.h" -#include "ns3/point-to-point-net-device.h" -#include "ns3/point-to-point-topology.h" -#include "ns3/udp-echo-client.h" -#include "ns3/udp-echo-server.h" -#include "ns3/simulator.h" -#include "ns3/nstime.h" -#include "ns3/ascii-trace.h" -#include "ns3/pcap-trace.h" -#include "ns3/global-route-manager.h" - -NS_LOG_COMPONENT_DEFINE ("PointToPointSimulation"); - -using namespace ns3; - -// Network topology -// -// point to point -// +--------------+ -// | | -// n0 n1 -// -int -main (int argc, char *argv[]) -{ - LogComponentEnable ("PointToPointSimulation", LOG_LEVEL_INFO); - - NS_LOG_INFO ("Point to Point Topology Simulation"); - - Ptr n0 = CreateObject (); - Ptr n1 = CreateObject (); - - Ptr link = PointToPointTopology::AddPointToPointLink ( - n0, n1, DataRate (38400), MilliSeconds (20)); - - PointToPointTopology::AddIpv4Addresses (link, n0, "10.1.1.1", - n1, "10.1.1.2"); - - uint16_t port = 7; - - Ptr client = CreateObject (n0, "10.1.1.2", - port, 1, Seconds(1.), 1024); - - Ptr server = CreateObject (n1, port); - - server->Start(Seconds(1.)); - client->Start(Seconds(2.)); - - server->Stop (Seconds(10.)); - client->Stop (Seconds(10.)); - - AsciiTrace asciitrace ("tutorial.tr"); - asciitrace.TraceAllQueues (); - asciitrace.TraceAllNetDeviceRx (); - - Simulator::Run (); - Simulator::Destroy (); -} -@end verbatim - -@section A Star Network -A point-to-point network is considered a special case of a star network. As -you might expect, the process of constructing a star network is an extension -of the very simple process used for a point-to-point link. We have provided -a file for you in the @code{tutorial} directory called @code{tutorial-star.cc} -that implements a simple star network as seen below. - -@sp 1 -@center @image{figures/star,,,,png} - -In order to create a star network, we need to be able to instantiate some -number (greater than one) of net devices on a node. In the name of simplicity -of use, the @code{PointToPointTopology} topology helper does not allow one to -do this. We provided a separate topology helper class, the -@code{PointToPointIpv4Topology} helper class that provides the slightly finer -granularity we need to accomplish a star network. In order to use this new -helper we have to load the definitions by including the appropriate file. - -@verbatim - #include "ns3/point-to-point-ipv4-topology.h" -@end verbatim - -The star that we're going to create has a node in the center (@code{n0}) with -six nodes surrounding (@code{n1} - @code{n6}). You should be able to easily -find and understand the code that creates these nodes. - -@verbatim - Ptr n0 = CreateObject (); - Ptr n1 = CreateObject (); - Ptr n2 = CreateObject (); - Ptr n3 = CreateObject (); - Ptr n4 = CreateObject (); - Ptr n5 = CreateObject (); - Ptr n6 = CreateObject (); -@end verbatim - -Next, we get into the differences between the @code{PointToPointTopology} -helper and the @code{PointToPointIpv4Topology} helper. The -@code{PointToPointIpv4Topology} helper looks and feels a little like the -@code{CsmaIpv4Topology} helper. Just like you created a CSMA channel -previously, you need to create a point-to-point channel. The following -code creates a @code{PointToPointChannel} and calls it @code{link01}. You can -interpret this name as being the channel (or @emph{link}) from node zero to -node one. - -@verbatim - Ptr link01 = - PointToPointIpv4Topology::CreateChannel (DataRate (38400), - MilliSeconds (20)); -@end verbatim - -You need to provide a data rate for the channel which we set at 38400 bits -per second. You must also provide a speed-of-light delay which we set at -20 milliseconds. - -Just as you added a net device to the nodes in the CSMA tutorial section, you -do the same here but with a point-to-point net device. The following code -illustrates how we do that: - -@verbatim - uint32_t nd01 = PointToPointIpv4Topology::AddNetDevice (n0, - link01); -@end verbatim - -We call the @code{PointToPointIpv4Topology} helper and ask it to add a net -device to node zero (@code{n0}) and connect it to the appropriate -point-to-point link (@code{link01}) which you will recall is the serial link -from node zero to node one. - -If you look at the following code, you will see the same calls are repeated -to create the remaining five point-to-point channels and connect them -to net devices on node zero. - -The next new code is found after the ``spokes'' of the star have been created. -It looks like the following: - -@verbatim - uint32_t nd1 = PointToPointIpv4Topology::AddNetDevice (n1, link01); - uint32_t nd2 = PointToPointIpv4Topology::AddNetDevice (n2, link02); - uint32_t nd3 = PointToPointIpv4Topology::AddNetDevice (n3, link03); - uint32_t nd4 = PointToPointIpv4Topology::AddNetDevice (n4, link04); - uint32_t nd5 = PointToPointIpv4Topology::AddNetDevice (n5, link05); - uint32_t nd6 = PointToPointIpv4Topology::AddNetDevice (n6, link06); -@end verbatim - -Here we are creating the net devices on the nodes surrounding the center node. -In the first call, we are adding a net device on node one (@code{n1}) and -connecting that net device to the channel named @code{link01}. Remember that -we created the channel @code{link01} as the channel connecting node zero and -node one. We previously created a net device on node zero and attached that -device to @code{link01}. Here we are connecting the other side of that link -to node one. The return value from this call is the net device index of the -created net device. - -The next section of code adds addresses to the net devices we just created. -The first call adds the IP address 10.1.1.1 to the net device going from -node zero to node one. Recall that we first created a node named @code{n0} -and a channel called @code{link01}. We added a net device to @code{n0} and -remembered the net device index as the @code{uint32_t nd01}. This meant -the net device @emph{nd} on node @emph{0} that we connected to node @emph{1}. -We call @code{AddAddress} to add an IP address (10.1.1.1) to the net device -on node zero identified by the net device index @code{nd01}. We provide a -net mask suitable for a point to point network. This is typically a /30 -address but we don't force that in this API. - -After setting up the address on node zero, we do the same for the node on -the other end of the ``spoke'' --- in this case node one, with its single -net device. Note that the network number is the same on both sides of this -network. - -@verbatim - PointToPointIpv4Topology::AddAddress (n0, nd01, "10.1.1.1", - ``255.255.255.252''); - - PointToPointIpv4Topology::AddAddress (n1, nd1, "10.1.1.2", - ``255.255.255.252''); -@end verbatim - -The following code repeats this pattern assining similar IP addresses to the -remaining net devices. Note that there are no @code{Mac48Address} address -assignments --- they are not required. - -The rest of the code you should recognize and understand. We are just going -to echo one packet across the point-to-point link. You should be now be able -to build and run this example and to locate and interpret the ASCII trace -file. This is left as an exercise for you. - -The file @code{tutorial-star.cc} is reproduced here for your convenience: - -@verbatim -/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */ -/* - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License version 2 as - * published by the Free Software Foundation; - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA - */ - -#include "ns3/log.h" -#include "ns3/ptr.h" -#include "ns3/internet-stack.h" -#include "ns3/point-to-point-channel.h" -#include "ns3/mac48-address.h" -#include "ns3/point-to-point-net-device.h" -#include "ns3/point-to-point-ipv4-topology.h" -#include "ns3/udp-echo-client.h" -#include "ns3/udp-echo-server.h" -#include "ns3/simulator.h" -#include "ns3/nstime.h" -#include "ns3/ascii-trace.h" -#include "ns3/pcap-trace.h" -#include "ns3/global-route-manager.h" - -NS_LOG_COMPONENT_DEFINE ("StarSimulation"); - -using namespace ns3; - -// Network topology -// -// n3 n2 -// | / -// | / -// n4 --- n0 --- n1 -// / | -// / | -// n5 n6 - -int -main (int argc, char *argv[]) -{ - LogComponentEnable ("StarSimulation", LOG_LEVEL_INFO); - - NS_LOG_INFO ("Star Topology Simulation"); - - Ptr n0 = CreateObject (); - Ptr n1 = CreateObject (); - Ptr n2 = CreateObject (); - Ptr n3 = CreateObject (); - Ptr n4 = CreateObject (); - Ptr n5 = CreateObject (); - Ptr n6 = CreateObject (); - - Ptr link01 = - PointToPointIpv4Topology::CreateChannel (DataRate (38400), - MilliSeconds (20)); - - uint32_t nd01 = PointToPointIpv4Topology::AddNetDevice (n0, - link01); - - Ptr link02 = - PointToPointIpv4Topology::CreateChannel (DataRate (38400), - MilliSeconds (20)); - - uint32_t nd02 = PointToPointIpv4Topology::AddNetDevice (n0, - link02); - - Ptr link03 = - PointToPointIpv4Topology::CreateChannel (DataRate (38400), - MilliSeconds (20)); - - uint32_t nd03 = PointToPointIpv4Topology::AddNetDevice (n0, - link03); - - Ptr link04 = - PointToPointIpv4Topology::CreateChannel (DataRate (38400), - MilliSeconds (20)); - - uint32_t nd04 = PointToPointIpv4Topology::AddNetDevice (n0, - link04); - - Ptr link05 = - PointToPointIpv4Topology::CreateChannel (DataRate (38400), - MilliSeconds (20)); - - uint32_t nd05 = PointToPointIpv4Topology::AddNetDevice (n0, - link05); - - Ptr link06 = - PointToPointIpv4Topology::CreateChannel (DataRate (38400), - MilliSeconds (20)); - - uint32_t nd06 = PointToPointIpv4Topology::AddNetDevice (n0, link06); - - uint32_t nd1 = PointToPointIpv4Topology::AddNetDevice (n1, link01); - uint32_t nd2 = PointToPointIpv4Topology::AddNetDevice (n2, link02); - uint32_t nd3 = PointToPointIpv4Topology::AddNetDevice (n3, link03); - uint32_t nd4 = PointToPointIpv4Topology::AddNetDevice (n4, link04); - uint32_t nd5 = PointToPointIpv4Topology::AddNetDevice (n5, link05); - uint32_t nd6 = PointToPointIpv4Topology::AddNetDevice (n6, link06); - - PointToPointIpv4Topology::AddAddress (n0, nd01, "10.1.1.1", - "255.255.255.252"); - - PointToPointIpv4Topology::AddAddress (n1, nd1, "10.1.1.2", - "255.255.255.252"); - - PointToPointIpv4Topology::AddAddress (n0, nd02, "10.1.2.1", - "255.255.255.252"); - - PointToPointIpv4Topology::AddAddress (n2, nd2, "10.1.2.2", - "255.255.255.252"); - - PointToPointIpv4Topology::AddAddress (n0, nd03, "10.1.3.1", - "255.255.255.252"); - - PointToPointIpv4Topology::AddAddress (n3, nd3, "10.1.2.2", - "255.255.255.252"); - - PointToPointIpv4Topology::AddAddress (n0, nd04, "10.1.4.1", - "255.255.255.252"); - - PointToPointIpv4Topology::AddAddress (n4, nd4, "10.1.4.2", - "255.255.255.252"); - - PointToPointIpv4Topology::AddAddress (n0, nd05, "10.1.5.1", - "255.255.255.252"); - - PointToPointIpv4Topology::AddAddress (n5, nd5, "10.1.5.2", - "255.255.255.252"); - - PointToPointIpv4Topology::AddAddress (n0, nd06, "10.1.6.1", - "255.255.255.252"); - - PointToPointIpv4Topology::AddAddress (n6, nd6, "10.1.6.2", - "255.255.255.252"); - - uint16_t port = 7; - - Ptr client = CreateObject (n0, "10.1.1.2", - port, 1, Seconds(1.), 1024); - - Ptr server = CreateObject (n1, port); - - server->Start(Seconds(1.)); - client->Start(Seconds(2.)); - - server->Stop (Seconds(10.)); - client->Stop (Seconds(10.)); - - AsciiTrace asciitrace ("tutorial.tr"); - asciitrace.TraceAllQueues (); - asciitrace.TraceAllNetDeviceRx (); - - Simulator::Run (); - Simulator::Destroy (); -} -@end verbatim - -@subsection Routing -If you are really excited about this simulator you may have already tried to -modify the scripts outside the tutorial. I know that one of the first things -that would have occurred to me when I saw the star network would have been to -start trying to add applications to echo packets from nodes other than zero. -If you tried, for example, to start the echo client on node one instead of -node zero, you would have found an empty trace file. The reason for this -is that you have now created an internetwork. This means you will need to -enable internetwork routing. - -We have provided a file for you in the @code{tutorial} directory called -@code{tutorial-star-routing.cc} to show you how this is done. This extremely -tricky and difficult change is shown below: - -@verbatim - GlobalRouteManager::PopulateRoutingTables (); -@end verbatim - -This one-line addition, located just before the simulation runs, tells the -@command{ns-3} @emph{global route manager} to walk the topology you created and -build internetwork routing tables for all of the nodes in the simulation. -We changed the client application so that it runs on node four: - -@verbatim - Ptr client = CreateObject (n4, "10.1.1.2", - port, 1, Seconds(1.), 1024); -@end verbatim - -Now if you build and run @code{tutorial-star-routing.cc} you can examine the -@code{tutorial.tr} file and see that your UDP echo packets are now correctly -routed through the topology. - -@section A Dumbbell Network -One of the most interesting simple topologies (from a phenomenological point of -view) is commonly called a dumbbell network. The name derives from a -superficial similarity in form to a piece of exercise equipment. - -The dumbbell model is typically composed of two bus or star network elements -connected via a point-to-point link. The point-to-point link is usually -configured with a lower bandwidth than the bus elements to provide a -@emph{choke point}. - -The following is a representation of the topology. - -@sp 1 -@center @image{figures/dumbbell,,,,png} - -We have provided a file that constructs this dumbbell network and creates -enough data flowing across the choke point that some packets will be dropped. -The file is called @code{tutorial-linear-dumbbell.cc} and is located in the -@code{tutorial} directory. We have already covered all of the code used to -create this network, so we will just quickly go over the main sections of the -script. - -The first section creates a CSMA lan that will become the left side of the -dumbbell network. This code should be very familiar since we used the same -process to create our first example. - -@verbatim -// -// Create the lan on the left side of the dumbbell. -// - Ptr n0 = CreateObject (); - Ptr n1 = CreateObject (); - Ptr n2 = CreateObject (); - Ptr n3 = CreateObject (); - - Ptr lan1 = - CsmaTopology::CreateCsmaChannel (DataRate (10000000), MilliSeconds (2)); - - uint32_t nd0 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n0, lan1, - "08:00:2e:00:00:00"); - - uint32_t nd1 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n1, lan1, - "08:00:2e:00:00:01"); - - uint32_t nd2 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n2, lan1, - "08:00:2e:00:00:02"); - - uint32_t nd3 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n3, lan1, - "08:00:2e:00:00:03"); - - CsmaIpv4Topology::AddIpv4Address (n0, nd0, "10.1.1.1", "255.255.255.0"); - CsmaIpv4Topology::AddIpv4Address (n1, nd1, "10.1.1.2", "255.255.255.0"); - CsmaIpv4Topology::AddIpv4Address (n2, nd2, "10.1.1.3", "255.255.255.0"); - CsmaIpv4Topology::AddIpv4Address (n3, nd3, "10.1.1.4", "255.255.255.0"); -@end verbatim - -The code to generate the CSMA lan on the right side is similar; only the names -have been changed. - -@verbatim -// -// Create the lan on the right side of the dumbbell. -// - Ptr n4 = CreateObject (); - Ptr n5 = CreateObject (); - Ptr n6 = CreateObject (); - Ptr n7 = CreateObject (); - - Ptr lan2 = - CsmaTopology::CreateCsmaChannel (DataRate (10000000), MilliSeconds (2)); - - uint32_t nd4 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n4, lan2, - "08:00:2e:00:00:04"); - - uint32_t nd5 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n5, lan2, - "08:00:2e:00:00:05"); - - uint32_t nd6 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n6, lan2, - "08:00:2e:00:00:06"); - - uint32_t nd7 = CsmaIpv4Topology::AddIpv4CsmaNetDevice (n7, lan2, - "08:00:2e:00:00:07"); - - CsmaIpv4Topology::AddIpv4Address (n4, nd4, "10.1.2.1", "255.255.255.0"); - CsmaIpv4Topology::AddIpv4Address (n5, nd5, "10.1.2.2", "255.255.255.0"); - CsmaIpv4Topology::AddIpv4Address (n6, nd6, "10.1.2.3", "255.255.255.0"); - CsmaIpv4Topology::AddIpv4Address (n7, nd7, "10.1.2.4", "255.255.255.0"); -@end verbatim - -Next, we create a point to point link to connect the two lans. We connect -the point-to-point channel between nodes three (on the left lan) and four -(on the right lan). You should recognize this as substantially similar to -the link setup from the @code{point-to-point} example. - -@verbatim -// -// Create the point-to-point link to connect the two lans. -// - Ptr link = PointToPointTopology::AddPointToPointLink ( - n3, n4, DataRate (38400), MilliSeconds (20)); - - PointToPointTopology::AddIpv4Addresses (link, n3, "10.1.3.1", - n4, "10.1.3.2"); -@end verbatim - -Then we configure data flows. We create four echo clients that send UDP -packets from the left side lan to servers created on the right side lan. -Notice that we send 100 packets with an inter-packet gap of ten milliseconds -instead of the single packet we have previously used. This data rate is -sufficient to saturate the point-to-point link and will cause packets to be -dropped when the queue on the link net devices overflows (the default maximum -queue depth is 100 packets). Note that we stagger the start of the echo -clients to slowly bring up the data rates. - -@verbatim -// -// Create data flows across the link: -// n0 ==> n4 ==> n0 -// n1 ==> n5 ==> n1 -// n2 ==> n6 ==> n2 -// n3 ==> n7 ==> n3 -// - uint16_t port = 7; - - Ptr client0 = CreateObject (n0, "10.1.2.1", - port, 100, Seconds(.01), 1024); - Ptr client1 = CreateObject (n1, "10.1.2.2", - port, 100, Seconds(.01), 1024); - Ptr client2 = CreateObject (n2, "10.1.2.3", - port, 100, Seconds(.01), 1024); - Ptr client3 = CreateObject (n3, "10.1.2.4", - port, 100, Seconds(.01), 1024); - - Ptr server4 = CreateObject (n4, port); - Ptr server5 = CreateObject (n5, port); - Ptr server6 = CreateObject (n6, port); - Ptr server7 = CreateObject (n7, port); - - server4->Start(Seconds(1.)); - server5->Start(Seconds(1.)); - server6->Start(Seconds(1.)); - server7->Start(Seconds(1.)); - - client0->Start(Seconds(2.)); - client1->Start(Seconds(2.1)); - client2->Start(Seconds(2.2)); - client3->Start(Seconds(2.3)); - - server4->Stop (Seconds(10.)); - server5->Stop (Seconds(10.)); - server6->Stop (Seconds(10.)); - server7->Stop (Seconds(10.)); - - client0->Stop (Seconds(10.)); - client1->Stop (Seconds(10.)); - client2->Stop (Seconds(10.)); - client3->Stop (Seconds(10.)); -@end verbatim - -The remainder of the file should be quite familiar to you. Go ahead and -run @code{tutorial-linear-dumbbell}. Now take a look at the trace -(@code{tutorial.tr}) file. You will now see trace lines that begin with -@code{d}. Alternatively you can search for the string ``queue-drop'' which -is the expansion of the drop code ('d'). - -Interpretation of a dropped packet is straightforward. We have expanded -the first @code{queue-drop} trace for you below. See the section on ASCII -tracing for details. - -@verbatim - 00 d - 01 2.40938 - 02 nodeid=3 - 03 device=1 - 04 queue-drop - 05 pkt-uid=124 - 06 LLCSNAP(type 0x800) - 07 IPV4( - 08 tos 0x0 - 09 ttl 63 - 10 id 20 - 11 offset 0 - 12 flags [none] - 13 length: 1052) 10.1.1.3 > 10.1.2.3 - 14 UDP(length: 1032) - 15 49153 > 7 - 16 DATA (length 1024) -@end verbatim - -We leave it as an exercise to examine the trace files in more detail. - -@c ======================================================================== -@c Nonlinear Thinking -@c ======================================================================== - -@node Nonlinear-Thinking -@chapter Nonlinear Thinking - -One thing that all of our examples so far have in common is that they are -composed of a linear collection of calls into the @command{ns-3} system. The -programmers among the readers may have wondered why there is not as much -as a for-loop in all of the examples. The answer is that we wanted to -introduce you to @command{ns-3} scripting with a minimum of conceptual -overhead. We're going to remedy that situation shortly. - -We have written a number of @command{ns-3} scripts in C++. Although we have -been perfectly linear in our script implementations, just like any other C++ -program, an @command{ns-3} script can use any features of the language you -desire. If you will look back at the @code{tutorial-linear-dumbbell.cc} -example, you may notice that the code to create the left and right sides of -the dumbbell is operationally identical --- only the names change. An obvious -improvement of this program would be to use subroutines to create the sides. -Since we are working with C++, we should probably do this in an -object-oriented way. Since object-oriented design is somewhat of a black art -to some people, we'll take some time here and outline a simple methodology -you can follow. - -@section Object Design 101 --- Class Ipv4BusNetwork -If you are a master of object oriented design, feel free to skip or skim this -section, in which we derive a simplistic but fully operational bus network -class. - -So you want to create a BusNetwork class. Often the biggest hurdle in a -design is figuring out how to get started. One of the simplest and most -straightforward ways to do an object decomposition of a problem is to simply -write down a description of the problem and take a look at the words -you used. Let's take some time and do that, first at a very high level. - -@example -A bus network is an implementation of a particular network topology that -contains some number of nodes. Each of these nodes is attached to a single -multi-drop channel. The network itself has some attributes independent of -the topology such as a network mask, network number (prefix) and base IP -address. -@end example - -The first thing to do is to focus on the nouns and adjectives. These will -give you a starting point for required classes and member variables. - -Immediately we can notice that at the highest level we are talking about the -noun @emph{network}. This probably won't surprise you. We also have an -adjective that modifies the noun --- @emph{bus}. This should lead us to our -first class definition. Usually class names are constructed in the same way -as an English language sentence would be spoken. For example, one would speak -of a @emph{bus network} in conversation, so we would normally create a -@code{class BusNetwork} to represent it. - -One thing to note is that we have used two words in our description quite -naturally: @emph{is} and @emph{has}. When you see these words should should -immediately think of the object-oriented concepts of @emph{ISA} (inheritance) -and @emph{HASA} (containment) respectively. We wrote that a bus network -@emph{is} an implementation of a particular network topology. Perhaps you -will agree that there is a natural base class called @code{Network} that -@emph{has} the attributes discussed above. The fact that a @code{BusNetwork} -@emph{ISA} kind of @code{Network} suggests inheritance. Let's capture that -thought right away remembering that we're focused on IP version four here: - -@verbatim - class Ipv4Network - { - public: - Ipv4Address m_network; - Ipv4Mask m_mask; - Ipv4Address m_baseAddress; - }; - - class Ipv4BusNetwork : public Ipv4Network - { - }; -@end verbatim - -Let's take a look at the @emph{HASA} relationships of the bus network. Clearly -it will @emph{have} a reference to the underlying channel that implements the -actual communications medium. We use smart pointers for those references, so -one member variable is obvious: - -@verbatim - Ptr m_channel; -@end verbatim - -A bus network will also need to contain references to all of the nodes we -eventually want to create. If you are working in C++ and see the words contain -or container, you should immediately think of the Standard Template Library -or STL. A quick search of the available containers there will probably lead -you to consider the vector class. A vector is a container that looks like an -array. This is just what we need here. Again, we want to use smart pointers -to reference our nodes, so the declaration of the vector would look like, - -@verbatim - std::vector > m_nodes; -@end verbatim - -It will save you headaches in the future if you notice that the space between -the two right brackets is required to differentiate this situation from a -right-shift operator. So we have a pretty good start already after just a -little work. Now we need to turn our attention to actions. Let's write -another little description of the things you consider doing to a Bus network. - -@example -We need to be able to create a bus network. We need to be able to delete a -bus network. We need to be able to get a handle to a node in order to add -applications. We need to be able to set the network, mask and base address -somehow, specify how many nodes to create and provide the underlying channel -its required bandwidth and delay parameters. -@end example - -We now look at the @emph{verbs} in that sentence. These will give a good -starting point for the methods of the classes. For example, the verbs -@emph{create} and @emph{delete} should suggest @emph{constructor} and -@emph{destructor}. The verb @emph{get} leads us to providing a method called -@code{GetNode}. We have to provide a number of parameters so we can either -provide @emph{setters} or we can simply pass them in as parameters to our -constructors. Since this is a simple example, we won't bother to implement -getters and setters (methods to get and set member variables to enhance data -hiding). Let's use this guidance to finish up our class declarations: - -@verbatim - class Ipv4Network - { - public: - Ipv4Network (Ipv4Address network, Ipv4Mask mask, Ipv4Address address); - virtual ~Ipv4Network (); - - Ipv4Address m_network; - Ipv4Mask m_mask; - Ipv4Address m_baseAddress; - }; - - class Ipv4BusNetwork : public Ipv4Network - { - public: - Ipv4BusNetwork ( - Ipv4Address network, - Ipv4Mask mask, - Ipv4Address startAddress, - DataRate bps, - Time delay, - uint32_t n); - - virtual ~Ipv4BusNetwork (); - - Ptr GetNode (uint32_t n); - - private: - std::vector > m_nodes; - Ptr m_channel; - }; -@end verbatim - -That's it. We have actually already walked through almost all of the code -required to construct a bus network in our @code{tutorial-csma-echo.cc} -example, so let's just jump forward and take a look at an implementation -of this thing. We provide an implementation for you in the files -@code{ipv4-bus-network.h} and @code{ipv4-bus-network.cc} located in the -@code{tutorial} directory. We also provide an example that uses the new -class in the file @code{tutorial-bus-network.cc}. - -The interesting method from our current perspective is the Ipv4BusNetwork -constructor, shown below: - -@verbatim - Ipv4BusNetwork::Ipv4BusNetwork ( - Ipv4Address network, - Ipv4Mask mask, - Ipv4Address baseAddress, - DataRate bps, - Time delay, - uint32_t n) - : - Ipv4Network (network, mask, baseAddress) - { - Ipv4AddressGenerator::SeedNetwork (mask, network); - Ipv4AddressGenerator::SeedAddress (mask, baseAddress); - - m_channel = CsmaTopology::CreateCsmaChannel (bps, delay); - - for (uint32_t i = 0; i < n; ++i) - { - Ptr node = CreateObject (); - uint32_t nd = CsmaIpv4Topology::AddIpv4CsmaNetDevice (node, m_channel, - Mac48Address::Allocate ()); - Ipv4Address address = Ipv4AddressGenerator::AllocateAddress (mask, - network); - CsmaIpv4Topology::AddIpv4Address (node, nd, address, mask); - m_nodes.push_back (node); - } - } -@end verbatim - -Notice that we do the simple and straightforward thing and pass all of our -parameters to the constructor. For those unfamiliar with C++, the line after -the colon and before the opening brace (shown below), - -@verbatim - : - Ipv4Network (network, mask, baseAddress) - { -@end verbatim - -Passes the appropriate parameters to the constructor of the base class -@code{Ipv4Network}. There are two new calls that we haven't seen immediately -after this initialization. They are: - -@verbatim - Ipv4AddressGenerator::SeedNetwork (mask, network); - Ipv4AddressGenerator::SeedAddress (mask, baseAddress); -@end verbatim - -We provide an IP address generator class to allow us to programmatically -allocate IP addresses. The first call to @code{SeedNetwork} gives the -address generator a starting network number to use when generating addresses. -The second call to @code{SeedAddress} gives the address generator a starting -IP address to use. There is a starting network and starting address for each -of the 32 possible network masks. Later in the for loop, you will see a -call to @code{AllocateAddress} in which the IP address for each node created -in the loop is actually generated. - -The only unfamiliar call in the reset of the constructor will be: - -@verbatim - m_nodes.push_back (node); -@end verbatim - -This is the STL code to add the newly created node to the vector of nodes -attached to the bus. - -For your convenience, we reproduce the entire bus network implementation below: - -@verbatim - /* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */ - /* - * Copyright (c) 2007 University of Washington - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License version 2 as - * published by the Free Software Foundation; - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA - */ - - #include "ns3/mac48-address.h" - #include "ns3/csma-net-device.h" - #include "ns3/csma-topology.h" - #include "ns3/csma-ipv4-topology.h" - - #include "ipv4-bus-network.h" - #include "ipv4-address-generator.h" - - namespace ns3 { - - Ipv4Network::Ipv4Network ( - Ipv4Address network, - Ipv4Mask mask, - Ipv4Address address) - : - m_network (network), m_mask (mask), m_baseAddress (address) - { - } - - Ipv4Network::~Ipv4Network () - { - } - - Ipv4BusNetwork::Ipv4BusNetwork ( - Ipv4Address network, - Ipv4Mask mask, - Ipv4Address baseAddress, - DataRate bps, - Time delay, - uint32_t n) - : - Ipv4Network (network, mask, baseAddress) - { - Ipv4AddressGenerator::SeedNetwork (mask, network); - Ipv4AddressGenerator::SeedAddress (mask, baseAddress); - - m_channel = CsmaTopology::CreateCsmaChannel (bps, delay); - - for (uint32_t i = 0; i < n; ++i) - { - Ptr node = CreateObject (); - uint32_t nd = CsmaIpv4Topology::AddIpv4CsmaNetDevice (node, m_channel, - Mac48Address::Allocate ()); - Ipv4Address address = Ipv4AddressGenerator::AllocateAddress (mask, - network); - CsmaIpv4Topology::AddIpv4Address (node, nd, address, mask); - m_nodes.push_back (node); - } - } - - Ipv4BusNetwork::~Ipv4BusNetwork () - { - } - - Ptr - Ipv4BusNetwork::GetNode (uint32_t n) - { - return m_nodes[n]; - } - - }; // namespace ns3 -@end verbatim - -@section Using Ipv4BusNetwork -If all you ever want to do with a bus network can be captured in a topology -with four nodes on the bus, the preceeding section may seem like a colossal -waste of time. This is probably not the case, though. Now that we have a -relatively abstract bus class, we can create bus networks with 4, 40 or 4000 -nodes with no additional effort. - -A use of the bus network class is shown in the file -@code{bus-network.cc} located in the @code{tutorial} directory. The -interesting code is, - -@verbatim - Ipv4BusNetwork bus ("10.1.0.0", "255.255.0.0", "0.0.0.3", - DataRate(10000000), MilliSeconds(20), 10); -@end verbatim - -Here we create a bus network with the network number ``10.1.0.0'' and the -network mask ``255.255.0.0'' that completes the IP network definition. You -can consider these together as ``10.1.0.0/16'' if you prefer. The next -parameter tells the bus to start numbering IP addresses of contained nodes at -``10.1.0.3'' (remember the network number will be combined). We provided a -data rate of 10 megabits per second and a latency of 20 milliseconds. -Finally, we ask the @code{Ipv4BusNetwork} object to create ten nodes in the -network. - -If you are feeling brave, go ahead and change the number of nodes to be 100, -1000, 10,000 or more to generate larger and larger networks. Before you go -too far, remember that a trace file will be generated when you run your -resulting program and ee asked the trace facility to trace all net device -receive events. This will include the reception of the broadcast ARP request -by all of the nodes in the simulation, so this can add up quickly. - -@c ======================================================================== -@c Summary -@c ======================================================================== - -@node Summary -@chapter Summary - -This concludes the first part of the tutorial. We have focused on -using the @command{ns-3} system to construct various network topologies and to -simulate sendng data across the networks; and we've shown you how to use the -trace facility to get access to simulation results. - -We now encourage you to play with the system a little. Experiment with what -we have provided. Build a hierarchical network simulation. Perhaps exercise -your object design skills and create a new @code{Ipv4DumbbellNetwork} class -to create dumbbell networks using the Ipv4BusNetwork class we just created. -Hint: An Ipv4DumbbellNetwork @emph{has} two @code{Ipv4BusNetwork} objects; -a left side and a right side. - -In the next part of the tutorial we are going to drop down a level and begin -examining the lower levels of the system in more detail. We are going to -explain how to change the behavior of the system and eventually how to write -new models and applications. This is a good time to make sure that you -thoroughly understand what we've gone over so far. - -@c ======================================================================== -@c Object Model -@c ======================================================================== - -@node Object-Model -@chapter Object Model - -@cindex Object Model -There are two distinctly different meanings associated with the term Object -Model. The first speaks to the implementation of an object system --- a system -view; and the second speaks to the application programming interface (classes -or objects) one uses to access some service or system --- an application view. - -As an example of the system view sense of the term, the C++ language has an -associated object model that describes how objects are laid out in memory, -how virtual functions work, how inheritance is implemented, constructor and -destructor execution ordering, template instantiation, etc. - -@cindex API -@cindex DOM -@cindex Document Object Model -In the case of the application view, the Document Object Model is a good -example. In the words of W3C, the Document Object Model (DOM) is an -application programming interface (API) for HTML and XML documents. It defines -the logical structure of documents and the way a document is accessed and -manipulated. - -@cindex API -@cindex COM -@cindex Component Object Model -The Component Object Model (COM) from Microsoft actually spans both meanings -of the term and extends further into policy statements. From a system -perspective, COM specifies an interface definition language, the layout of -objects virtual function tables, the formats of Globally Unique Identifiers -and also specifies lifetime management mechanisms for objects via reference -counting. From the point of view of the API, COM specifies a number of -Interfaces as well as functions such as CoCreateInstance and various -threading models. The COM specification extends to policy by disallowing -implementation inheritance. - -@cindex Feynman -The @command{ns-3} object model takes the C++ language (system level) object -model as its basis, and extends that model by providing an API for software -componentry. You may find terms like Component, Interface and QueryInterface -in the following discussion, or used informally in other discussions about -@command{ns-3}. It is important to understand from the outset that this is -the @command{ns-3} object model, and not any other object model. -Richard Feynman (an American physicist) once described the behavior of matter -and light on a very small scale in the following way, - -@quotation -``They do not behave like waves, they do not behave like particles, they do -not behave like clouds, or billiard balls, or weights on springs, or like -anything that you have ever seen.'' -@end quotation - -Just as students of quantum mechanics must rid themselves of preconceptions -regarding the behavior of matter at small scales, you should rid yourself of -any preconceptions you may have about components, interfaces and APIs for -software componentry before continuing. To paraphrase Feynman, @command{ns-3} -components do not behave like COM Components, or Java Beans, or CORBA -objects, or clouds or weights on springs, or like anything that you have -ever seen --- they are @command{ns-3} components. - -@section The C++ Object Model is the Root of all Things -@command{Ns-3} is primarily a C++ system. The system is written in C++ and -one can use standard C++ mechanisms for creating and using ns-3 objects. We -do not change this at all, nor do we make any pronouncements about the -superiority of one mechanism or another. What we will do is provide -convenience functions that we think will make creating and managing simulation -objects easier. - -@cindex CreateObject -Previously, you have seen objects created using the template function -@code{CreateObject} as in the following example: - -@verbatim - Ptr n0 = CreateObject (); -@end verbatim - -This line of code, while it may be unfamiliar to some, is pure C++. If you -were to look in the header file ptr.h, you would find the following definition -of the @code{CreateObject} template. - -@verbatim - template - Ptr CreateObject (void) - { - Ptr p = Ptr (new T (), false); - p->SetTypeId (T::GetTypeId ()); - return p; - } -@end verbatim - -@cindex template -As you can see, this template creates objects of type @code{T} using the -operator @code{new}. Its a little harder to find the corresponding delete --- -it's in the file @code{object.cc} inside the method @code{Object::MaybeDelete}, -but when that @code{Ptr} which you see above goes out of scope it will call -@code{Unref} and ultimately the C++ @code{delete} operator will be called. - -@cindex new -@cindex delete -The ns-3 system uses the C++ @code{new} and @code{delete} operators, so there -is really no reason that you as a user of the ns-3 system are forbidden from -using these or any other C++ mechanism. If you so desire, you can take on -the responsibility for managing object lifetime (i.e., do not use the -@code{Ptr} smart pointer), work directly with the @code{new} and @code{delete} -operators and call methods like any C++ object as in the following example: - -@verbatim - MyClass *obj = new MyClass (); - obj->Method(); - delete obj; -@end verbatim - -@cindex model -You, as a competent model author, are encouraged to use whatever methods you -think are appropriate in your private code. Remember, however, that the -public ns-3 APIs do use smart pointers to pass objects around in an effort to -reduce the burden of object lifetime management. If you do intend to export -an API publicly, you should use the same object lifetime management approaches -as those found in the ns-3 public API if only for consistency. - -These APIs are there for convenience and consistency, but do not change the -fact that in ns-3 all of the objects are really just C++ objects, ultimately -created using the C++ new operator with C++ constructor semantics and are -ultimately deleted using the C++ delete operator, following C++ destructor -semantics. Although it may sometimes appear so, there is really no system- -level magic going on in ns-3. Ns-3 components and interfaces are C++ objects -just like any other object and our object model is simply a collection of APIs -built on the normal C++ object model. - -@cindex Interface -@cindex Abstract Data Type -@cindex ADT -@cindex Abstract Base Class -@cindex ABC -@section Interface -There are many different ideas floating around of what exactly the term -@emph{interface} means. Originally an interface just meant a communication -boundary between two entities. As the concepts of object oriented programming -(OOP) were surfacing in the 1980s, the term interface was applied to the -collection of access methods for the modular entities that were being defined. - -@cindex OOP -@cindex Object Oriented Programming -Two distinct approaches developed regarding specifying access mechanisms for -objects. The OOP purists were very concerned about object reuse and were led -to Abstract Data Types (ADT). These were eventually implemented in the case -of C++, as pure virtual methods in Abstract Base Classes (ABC). Another group -of folks was more interested in simply specifying object access methods in one -place and using inheritance as the primary reuse mechanism. - -Bjarne Stroustroup, the creator of C++, embraced both approaches. He makes -the following interesting observation: - -@quotation -``Many classes [@dots{}] are useful both as themselves and also as bases for -derived classes. [@dots{}] Some classes, such as class @strong{Shape}, -represent abstract concepts for which objects cannot exist.'' -@end quotation - -@cindex PIMPL -@command{Ns-3} does not pick and enforce a particular approach. In -@command{ns-3} an interface is determined completely by a class declaration -just as any C++ object interface is declared. If you think of an object as -an abstract concept that should be implemented by derived classes, by all -means, use the Abstract Base Class approach to interface declaration. If you -think that an object should be completely concrete and you foresee no need -to ever modify its behavior, feel free to avoid declaring any methods virtual. -If you think that an object could be useful as a base class, feel free to -declare its methods virtual. If you like to use the PIMPL idiom, again, feel -free. If you want to use any combination of these techniques, feel free. -We make no restrictions. - -@cindex API -When we speak of an ns-3 interface, we do not worry about interface definition -languages, or pure virtual classes, or registries we just think about C++ -object declarations and their associated methods. We tend to think of -interfaces to objects as simply a private or public API. When we instantiate -an @command{ns-3} interface, it is the C++ object model that dictates how that -object is brought into existence. When a method is called on an @command{ns-3} -Interface, it is the C++ object model that dictates how that method is -dispatched. - -We do, however, provide a base class that endows vanilla C++ objects with -capabilities that can be seen as conceptually similar to those provided by -Microsoft Component Model @emph{Interfaces}. - -@section The Ns-3 Object and GetObject -@cindex Component Object Model -One thing that Microsoft arguably got right in the Component Object Model was -the idea of Interface aggregation and discovery via QueryInterface. We have -embraced these ideas in @command{ns-3}. This was done primarily to address a -common problem in large software systems. A good example of this problem -happens in the @command{ns-3} Node class. - -@cindex OOP -@cindex weak base class -@cindex base class bloat -@cindex Swiss Army Knife class -@cindex Node -If one were to take the standard OOP view of specializing a @code{Node} into -an internet host, for example, one would typically inherit from the @code{Node} -base class and include functionality to implement such things as internet -routing and a TCP/IP protocol stack. Other types of @code{Node}s might -inherit from the node class and specialize in different ways, or further -specialize the internet host class, treating it as a base class. This can -result in a complicated inheritance tree in which some specializations are -simply not available to other branches of the tree which can make reuse -difficult or impossible. This is known as the @emph{weak base class} problem -and creates pressure to drive functionality up the inheritance tree into the -base classes. This, in turn, results in @emph{base class bloat} and the -resulting @emph{swiss army knife} base classes which end up trying to do -everything in one place. - -Even if one successfully avoided these swiss army knife base classes, one -would also want to be able to treat new specializations of @code{Node} -generically in the system. This means one would pass references to the base -class (@code{Node}) across public APIs. This introduces @emph{upcasts} prior -to passing across public APIs and corresponding @emph{downcasts} on the other -side in order to gain access to required specialized functions. As the -inheritance tree becomes more complicated, this approach can cause another -related problem known as the @emph{fragile base class} problem. This happens -when changes to the base class cause unexpected problems in the various and -sundry subclasses. - -These effects seem always to result in a positive feedback loop driving -everything into the base class and destroying much of the encapsulation which -is a hallmark of the object oriented approach. - -@subsection Interface Composition -@cindex Node -There is a completely different way to address the Node specialization -problem. Instead of approaching the situation using inheritance, one can -look at the problem as one of composition. We can look at the @code{Node} -class as a container of sorts that holds other objects. In this case, the -objects would be instances of the classes implementing the internetwork -routing code, or the TCP/IP protocol stack described above. This approach -preserves the encapsulation and solves the weak base class, base class bloat -and fragile base class problems; but the question of method dispatch -immediately comes to mind. - -@cindex delegation -In many systems, @emph{delegation} is used. The base class, @code{Node}, -in this approach would provide methods that simply forward to the objects -implementing the desired functionality. This situation clearly does not -address the base class bloat problem since dispatch methods must be added -to the base class. The situation is mitigated somewhat by pushing the -implementation of the dispatch methods to contained objects, but the -fundamental problems are still present. What is really needed is a way -to compose objects but at the same time keep the interfaces to those -objects separated. - -@cindex aggregation -Composition, usually called @emph{aggregation}, along with runtime Interface -discovery is the solution that Microsoft originally championed and that -@command{ns-3} has adopted --- albeit with many simplifications and a few name -changes. - -@subsection Objects and Interfaces -@cindex COM -@cindex QueryInterface -Now that we have mentioned Microsoft COM and are almost obligated to mention -the terms Interface and QueryInterface. For those familiar with COM, loosely -speaking, QueryInterface is to COM as GetObject is to @command{ns-3}. -The analogy, while good conceptually, is superficial from an implementation -point of view. - -@cindex Node -Addressing our current example of a @code{Node}, generically speaking, each -node needs to aggregate an object that will implement internetwork routing -and TCP/IP. The system will need to provide a mechanism for locating the -aggregated objects and allow a client to discover them. - -@cindex aggregation -@cindex Object -These aggregated objects have interfaces in the C++ sense of collections of -method signatures. In @command{ns-3}, when objects are capable of -participating in this aggregation process, they are called @command{ns-3} -@code{Objects}. @code{Objects} receive the functionality required for this - participation by inheriting from the @command{ns-3} base class @code{Object}. - -Note well that when we write the word @code{Object} (note the uppercase 'O' in -the spelling and the change of font) we are referring to a kind of C++ object -that has inherited the capability of participating in an aggregation. The -@command{ns-3}-specific word @code{Object} can have a significantly different -meaning than that of a vanilla C++ object outside the aforementioned -inheritance tree, and the difference is only readily apparent via context. -In this tutorial we will always write the @command{ns-3}-specific kind of -@code{Object} in a fixed font; and will write the vanilla C++ term object in -normal font. In conversation, you will need to be careful to understand which -term is meant: object or @code{Object}. - -Once an object has inherited from class @code{Object} it has the ability to -@emph{host} an aggregation. This means that it has the ability to add other -@code{Objects} to its aggregation via the method @code{AggregateObject}. It -also means that it can provide a service to @emph{discover} other objects in -its aggregation via the method @code{GetObject}. - -@cindex base class -Technically, the class named @code{Object} is simply a base class that you -will inherit from if you want your @code{Objects} to support aggregation and -discovery. Many systems have a base class that implements common -functionality and these base classes are typically called something like -Object. The @command{ns-3} version of this base class relates primarily to -@code{Object} aggregation and discovery, although it does also provide methods -to help with intrusive reference counting and tracing as well. - -When a C++ object inherits from the ns-3 Object base class, it is conceptually -promoted to an ns-3 @code{Object} irrespective of how the object was declared -(e.g., as an abstract base class, concrete class, with virtual methods, etc.). -In ns-3, you should associate inheritance from the class named @code{Object} -with promotion of an object to the status of some locatable @code{Object} -rather than with the form of the class declaration. - -@cindex COM -@cindex CORBA -@cindex ORBit -For those of you unfamiliar with Microsoft COM, CORBA or ORBit, this might -sound obvious. For those of with such a background, the point we are making -is that there is no such thing in @command{ns-3} as a separate Interface -declaration, no such thing as an Interface Definition Language, no such thing -as a UUID or GUID, etc. In @command{ns-3} we just work with C++ objects that -may be given some very useful abilities by inheriting from the @command{ns-3} -base class @code{Object}. @command{Ns-3} @code{Objects} are not required to -inherit from classes composed of pure virtual methods in order to define an -Interface. It's all really just ``plain old C++.'' - -To summarize, when you instantiate an object that inherits from the -@code{Object} class, you will have a C++ object that has four important -properties: - -@cindex AggregateObject -@cindex GetObject -@itemize @bullet -@item The @code{Object} has a C++ interface defined by the collection of method signatures in its inheritance tree; -@item The @code{Object} has some way to identify its underlying class uniquely; -@item The @code{Object} is a kind of container that has the ability to aggregate other @code{Objects} using the method @code{AggregateObject}; -@item The @code{Object} exports a method called @code{GetObject} that allows for discovery of other aggregated @code{Objects}. -@end itemize - -@cindex base class -@cindex Object -It is crucially important to understand what we have described here -(especially for those coming from other systems that provide similar -functionality). A given C++ class has an object access interface that is -essentially the collection of method signatures specified in its inheritance -tree. This is a C++ object model thing. Ns-3 provides a base class from -which the class in question can inherit and be promoted to the status of -@code{Object}. Once a class becomes an @code{Object} it has inherited the -ability to aggregate and search for other @code{Objects} that are added to -its aggregation. - -That last detail is important. In @command{ns-3} @code{Objects} are both -containers and specifications for a object method access. We have previously -mentioned that the @code{Node} class acts as a container. In fact, the -@code{Node} class inherits from @code{Object} and is itself an @command{ns-3} -@code{Object}. So, when the @code{Node} object is created it is really an -aggregation of one @code{Object} and you can call @code{AggregateObject} or -@code{GetObject} on the resulting @code{Node} object. Along with being an -aggregation, the @code{Node} class also describes a public interface. This -public interface (API) is declared just as any C++ object is declared, via its -class methods as specified in the inheritance tree. For those steeped in -COM or CORBA, this is where the concept of Interface works in @command{ns-3}. -Remember that it is generally true that @code{Objects} are both aggregations -and APIs. - -@subsection Aggregations -@cindex aggregate -The figure below shows how an @code{Object} could be illustrated in detail. -The line with the circle at the top of the diagram represents the appearance -of the @code{Object} API to the external world. This circle and line are -together called a lollipop because of its superficial similarity to a kind of -childs candy. - -@sp 1 -@center @image{oneobj,,,,png} - -@cindex API -You could declare this API and associated @code{Object} quite simply using a -non-virtual class as follows, - -@verbatim - class A : public Object { - public: - static ns3::TypeId GetTypeId (void) - { - static ns3::TypeId tid = ns3::TypeId ("A") - .SetParent (Object::GetTypeId ()) - .AddConstructor (); - return tid; - } - - A () - { - } - - void MethodA (void); - }; -@end verbatim - -The methods that are then available via the API labeled @code{A} in the -figure above are the methods inherited from the @code{Object} base class -(@code{GetObject}, @code{Ref}, and @code{Unref}) and those from class -@code{A} (@code{MethodA}). - -Note that you must declare a @code{TypeId} in your @code{Object} class, and -it must be declared static to make it class-wide in scope. This @code{TypeId} -is a unifying element in the @command{ns-3} object model and uniquely -identifies @code{Objects} at run-time as being instantiated from a particular -class. We'll have much more to say about @code{TypiId} shortly. - -You can think of the arc and arrow device coming off each side of the -illustrated @code{Objects} as part of a connector. These connectors allow -@code{GetObject} to search aggregations for an instance of a class type. -The figure below shows an aggregation of three @code{Objects}: A, B and C. -The class declarations for classes @code{B} and @code{C} are substantially -similar to that of class @code{A}. - -@sp 1 -@center @image{threeobj,,,,png} - -You can visualize these @code{Objects} as being snapped together like Lego -building blocks if you like. When @code{Objects} are aggregated, a -@code{GetObject} search path is formed through the connectors. In order -to create this aggregation you will first need to create the @code{Objects}. -These are just normal, everyday C++ objects that we can create using the -@code{CreateObject} template function and manage using smart pointers. The -following code should be obvious to you by now: - -@verbatim - Ptr a = CreateObject (); - Ptr b = CreateObject (); - Ptr c = CreateObject (); -@end verbatim - -@cindex aggregation -When you create an aggregation, you pick one of the @code{Objects} of the -aggregation to think of as the container. In this case well pick @code{Object} -A. In order to aggregate an @code{Object}, you simply call the method -@code{AggregateObject} that your class has inherited from class @code{Object}. -The following code will aggregate @code{Object B} and @code{Object C} onto -the @code{Object} (and container/aggregation) @code{A}. - -@cindex AggregateObject -@cindex GetObject -@cindex Object -@verbatim - a->AggregateObject (b); - a->AggregateObject (c); -@end verbatim - -Thats all there is to it. Now that you have those connectors snapped -together, you can ask each of the @code{Objects} in the aggregation for any of -the other @code{Objects} in the aggregation. Lets look at a simple example: - -@verbatim - Ptr newB = a->GetObject (); -@end verbatim - -Now, the explanation of what this snippet does is not as simple as writing it. -The left hand side of this assignment declares a smart pointer to the class -@code{B} to help with memory management of the returned @code{Object} pointer. -You should be very familiar with smart pointers at this stage of the tutorial. - -The right hand side illustrates how @code{GetObject} is acutally used. -The method @code{GetObject} is templated. The assocated template parameter -(between the brackets) specifies the @emph{class} that is being requested. -This is important. Since it is the class type that specifies the search -criterion, there can be only one instance of a particular class present in an -aggregation. Looking back a little, although the parameter to -@code{AggregateObject} appears to be a vanilla C++ object (@code{b} or @code{c} -above), it actually represents (is an instance of) a class that has an -associated @code{TypeId} and inherits from @code{Object}. When you call -@code{GetObject} you specify the search criterion (using the template -parameter) as a class name. This referenced class must also have an -associated @code{TypeId} and must also have inherited from @code{Object}. - -This may be summarized by saying that @code{AggregateObject} takes an -@emph{instance} of an object of a particular class that inherits from -@code{Object}. GetObject looks for a @emph{class} of a particular type -(that again inherits from @code{Object}) and possibly returns an aggregated -object instance of that type. - -Now that you have those conceptual connectors snapped together, you can ask -each of the @code{Objects} in the aggregation for any of the @code{Objects} -in the aggregation. For example we could walk the @code{Objects} asking each -for the next in the aggregation. First we would ask the @code{Object} pointed -to by the smart pointer @code{a} to look for the @code{Object} @code{class B}: - -@verbatim - Ptr newB = a->GetObject (); -@end verbatim - -Next, we can ask the @code{Object} pointed to by the smart pointer @code{newB} -to look for the @code{Object} representing @code{class C}: - -@verbatim - Ptr newC = newB->GetObject (); -@end verbatim - -@cindex Object -Then, we can ask the @code{Object} pointed to by the smart pointer @code{newC} -to look for the @code{Object} representing @code{class A} and complete our -circuit of the aggregation: - -@verbatim - Ptr newA = newC->GetObject (); -@end verbatim - -@cindex GetObject -@code{GetObject} has some important properties that we need to go over. -Technically, @code{GetObject} is a @emph{symmetric}, @emph{reflexive} and -@emph{transitive} operation with respect to the set of aggregated -@code{Objects}. - -@subsubsection Symmetry -@cindex symmetry -The symmetric nature of @code{GetObject} guarantees that if one performs a -@code{GetObject} on a given @code{Object} for the class of that same -@code{Object}, that @code{GetObject} must succeed. In other words, the -fact that you accessed the aggregation via an instance of an @code{Object A} -in the aggregation implies the reachability of that @code{Object} in the -aggregation. This is usually written (by Microsoft) as, - -@center must succeed (A >> A) - -We can illustrate this property with the code snippet, - -@verbatim - Ptr symmetricA = a->GetObject (); - NS_ASSERT (symmetricA); -@end verbatim - -Here we take as given an interface (smart) pointer --- named @code{a} --- on -which we perform a @code{GetObject} looking for the class that represents that -same @code{Object}. This call must always succeed and a smart pointer to the -aggregated instance of that class is returned. - -@subsubsection Reflexivity -@cindex reflexivity -Calls to @code{GetObject} must also be reflexive. This means that if you -successfully @code{GetObject} for @code{Object B} from @code{Object A}, then -you must always be able to @code{GetObject} for @code{A} from @code{B}. This -is usually written as, - -@center must succeed (A >> B, then B >> A) - -This property can be illustrated with the code snippet, - -@verbatim - Ptr b = a->GetObject (); - Ptr reflexiveA = b->GetObject (); - NS_ASSERT (reflexiveA); -@end verbatim - -If the first @code{GetObject} on @code{Object A} looking for @code{Object B} -succeeds, then a @code{GetObject} on @code{Object B} looking @code{Object A} -must succeed. - -@subsubsection Transitivity -@cindex transitivity -@code{GetObject} must also be transitive. This means that if one can -find @code{Object B} from @code{Object A}, and @code{Object C} from -@code{Object B}, then one must also be able to find @code{Object C} from -@code{Object A}. This is usually written as, - -@center must succeed (A >> B, and B >> C, then A >> C) - -This property can be illustrated with the code snippet, - -@verbatim - Ptr b = a->GetObject (); - Ptr c = b->GetObject (); - Ptr transitiveC = a->GetObject (); - NS_ASSERT (transitiveC); -@end verbatim - -If you can get to @code{Object B} from @code{Object A}, and you can get to -@code{Object C} from @code{Object B}, then a @code{GetObject} on -@code{Object A} looking for @code{Object C} must also succeed. - -@subsection Creating the TypeId -@cindex TypeId -@cindex GetTypeId -The final piece of this puzzle is the @code{TypeId}. Recall that the -declaration our example object above included the following code - -@verbatim - static ns3::TypeId GetTypeId (void) - { - static ns3::TypeId tid = ns3::TypeId ("A") - .SetParent (Object::GetTypeId ()) - .AddConstructor (); - return tid; - } -@end verbatim - -This is the bit of code that ties this all together. For those unfamiliar -with the idioms involved, this declaration can be rather dense. First, let's -examine the function declaration itself. The following code, - -@verbatim - static ns3::TypeId GetTypeId (void) ... -@end verbatim - -declares a function that will be associated with all of the instances of the -given class. This is a function, not a method, in that it can be accessed -without a @emph{this} pointer; but it is associated with the class in a -namespace sense. The use of this kind of declaration allows one to write, - -@verbatim - return A::GetTypeId (void); -@end verbatim - -if the @code{TypeId} is needed for our @code{class A}. More generically the -class name can be substituted in a template, as is done deep in the -@command{ns-3} object system. - -From this perspective, if you leave out the middle of the function definition, -the boundaries should make sense to you. - -@verbatim - static ns3::TypeId GetTypeId (void) - { - return tid; - } -@end verbatim - -@cindex function-local variable -You are obviously looking at a global function associated with your class -that simply returns a @code{TypeId}. Now, what about the rest. The code - -@verbatim - static ns3::TypeId tid = ns3::TypeId ("A") - .SetParent (Object::GetTypeId ()) - .AddConstructor (); -@end verbatim - -when found inside the function declaration is called a function-local variable -with associated initialization. It'll be easier to pick this statement apart -piece by piece as well. The first line, - -@verbatim - static ns3::TypeId tid = ... -@end verbatim - -is the declaration of the function-local variable tid. This is essentially -an initialized global variable, the scope of which has been reduced to within -the enclosing method. You can think of this as a kind of global variable -that can only be accessed right there where it is created. If the variable -is initialized, this amounts to the same behavior as if a global static -initializer was declared in a namespace of the same name as your class. -Global static initializers are guaranteed by the C++ language definition to -be executed before your main procedure is entered. So are function-local -variables. - -The variable that is being initialized is of type @code{ns3::TypeId}, is -named @code{A::tid} since it is inside the class declaration for -@code{class A}, and is initialized by a call to the constructor for the class -@code{TypeId}. The constructor for @code{TypeId} takes a @code{std::string} -that can be used to locate the type information for your class. We usually -privide the class name as the string. - -Hopefully, this much of the declaration is now clear: - -@verbatim - static ns3::TypeId GetTypeId (void) - { - static ns3::TypeId tid = ns3::TypeId ("A") - ... - return tid; - } -@end verbatim - -All that is left now are the lines including @code{SetParent} and -@code{AddConstructor}. - -@verbatim - static ns3::TypeId tid = ns3::TypeId ("A") - .SetParent (Object::GetTypeId ()) - .AddConstructor (); -@end verbatim - -The last bit may seem quite odd at first glance, but don't let the way the -code is broken up over several lines throw you. If you saw something like, - -@verbatim - pointer->TypeId()->SetParent()->AddConstructor(); -@end verbatim - -you probably wouldn't hesitate at all. Clearly, you would think, a method -called @code{TypeId} is called using the pointer called @code{pointer} as -shown below. - -@verbatim - pointer->TypeId() -@end verbatim - -The method @code{TypeId} must further return a pointer to an object that has -a method called @code{SetParent}. Just as clearly, @code{SetParent} must -return a pointer to an object that has a method called @code{AddConstructor}. -The same sort of thing is happening in our code snipped, except we are using -references instead of pointers. Perhaps if we rearrange this code to live on -one line it will be clearer. - -@verbatim - ns3::TypeId ("A").SetParent (Object::GetTypeId ()).AddConstructor (); -@end verbatim - -It's just a string of method calls. The remaining question is then, what do -those three methods do. - -The first, @code{ns3::TypeId ("A")}, simply allocates a new type in the system -and allows you to refer to it in the future by a string. We have mentioned -inheritance trees often in the previous discussion. The second method, -@code{SetParent} associates the class being defined with its parents in the -tree. Finally, the @code{AddConstructor} method allows you to specify a -constructor to be used when an instance of your class is created using -@code{CreateObject}. - -@verbatim - AddConstructor (); -@end verbatim - -You can interpret this as explaining to the @command{ns-3} object system that -you have a constructor named @code{A::A} which takes no parameters. You are -saying that this constructor should be used when @code{CreateObject} is called -with no parameters. - -By including the structure of the inheritance tree, in @command{ns-3} we can -use implementation inheritance to easily create new @code{Objects}. You are -prevented from doing so in Microsoft COM, but this was almost universally -identified as a problem. - -So, looking at the entire @code{GetTypeId} declaration again, - -@verbatim - static ns3::TypeId GetTypeId (void) - { - static ns3::TypeId tid = ns3::TypeId ("A") - .SetParent (Object::GetTypeId ()) - .AddConstructor (); - return tid; - } -@end verbatim - -it should be clear what is happening. - -@subsection A Very Real Example -@cindex Node -@cindex AggregateObject -@cindex GetObject -@cindex Object -At this point you may be asking yourself what the point of all of this is, -since you already had those pointers laying around when you created the -objects. The typical case is that one will create and aggregate some number -of @code{Objects} in a constructor and return only a pointer to a single -@code{Object} as in our canonical example with @code{class Node}. In this -case, the @code{Node} would be created and the @code{Node} constructor might -create and call @code{AggregateObject} to aggregate the @code{Objects} for -internetwork routing and TCP/IP. From an external point of view, these -aggregated objects may be discovered at run-time using @code{GetObject}. - -Generally one tends to think of one of the @code{Objects} in the aggregation -as being the container and other @code{Objects} being aggregated to that -container. In the case of a Node, for example, it is quite natural to think -of the Node as being the container which contains protocol stacks, internet -routing, etc. So, lets start thinking about a real example by calling the -container @code{Object Node} instead of @code{A} as we have been. The -creation of this @code{Object} is found all over our example programs. For -example, you will find code like the following in -@code{samples/simple-point-to-point.cc}: - -@verbatim - Ptr n = CreateObject (); -@end verbatim - -It may appear obvious to you now that the @code{InternetNode} class name -provided to the template function @code{CreateObject} means that -@code{InternetNode} is an @command{ns-3} @code{Object} and you will be able to -call @code{GetObject} on the resulting smart pointer. Well, I'm afraid that's -not entirely true. It's slightly more complicated. - -Take a look at @code{src/internet-stack/internet-stack.h} and find the class -declaration for @code{InternetNode}. - -@verbatim - class InternetNode : public Node - { - public: - InternetNode(); - ... - }; -@end verbatim - -@cindex GetTypeId -@cindex TypeId -@cindex Object -There is no declaration of a @code{static TypeId GetTypeId (void)} in this -class. This means that the @code{InternetNode} is really not an @code{Object} -for which you can @code{GetObject}. It turns out that the @code{InternetNode} -is an @emph{implementation class} of the @code{Node Object}. - -You may recall that there can be an implicit cast in a smart pointer -assignment if the cast is to a visible, unambiguous base class. That is, in -fact, what is happening here. Now, take a look at @code{src/node/node.h} and -find the class declaration for @code{class Node}. There you will find, - -@verbatim - class Node : public Object - { - public: - static TypeId GetTypeId (void); - ... - }; -@end verbatim - -Class @code{InternetNode} inherits from class @code{Node} that, in turn, -inherits from class @code{Object}. It is @code{Node} that provides a -@code{GetTypeId} method. Therefore it is @code{Node} that is an -@command{ns-3} @code{Object}. Note well that @code{InternetNode} is not an -@code{Object} in the sense that one should call @code{GetObject} on an -aggregation looking for an @code{InternetNode} class. That is, you should not -do, - -@verbatim - Ptr i = node->GetObject (); -@end verbatim - -since there really is not InternetNode::GetTypeId. It is @code{Node} that is -the @emph{proper} @code{Object} in this case and you should view -@code{InternetNode} as an implementation of the @code{Node Object}. This may -become clearer as we look a little deeper. - -We spoke of a protocol stack that is aggregated to a @code{Node} in our -discussions above, what we see in the real @command{ns-3} code is that this -is represented by the @code{Ipv4 Object}. If you look in -@code{src/node/ipv4.h} you will find, - -@verbatim - class Ipv4 : public Object - { - public: - static TypeId GetTypeId (void); - ... - }; -@end verbatim - -Since class @code{Ipv4} inherits from class @code{Object} and has a -@code{GetTypeId}, it is an @command{ns-3} @code{Object}. If you look in -@code{src/node/ipv4.cc} you will find, - -@verbatim -TypeId -Ipv4::GetTypeId (void) -{ - static TypeId tid = TypeId ("Ipv4") - .SetParent (); - return tid; -} -@end verbatim - -After all of this reading you know that this code snippet is asking the -system to create a unique @code{TypeId} for the @code{Ipv4} class and -declares that @code{Ipv4} inherits from class @code{Object}. This is what -makes an @code{Ipv4} an @code{Object}. - -@cindex Ipv4 -It turns out that the Ipv4 class is an abstract base class (ABC). There are -a number of pure virtual methods declared in that class. This means that -an @code{Ipv4} object may not be instantiated. This is reflected by the fact -that there are no constructors registered in the @code{GetTypeId} method above. -What is instantiated in the real system is an implementation class, called -@code{Ipv4Impl}. This class inherits from @code{Ipv4} and provides the -required virtual methods. This is where understanding what is an -@code{Object} and what is not can get tricky. The @code{Object} is the -@code{Ipv4} class since that is where the @code{GetTypeId} is found. The fact -that you see @code{GetTypeId} there tells you that the @code{Ipv4} class is -the class for which you can @code{GetObject}. - -@cindex implementation class -The class @code{Ipv4Impl} provides an implementation for the pure virtual -methods in @code{Ipv4}. Since class @code{Ipv4} cannot be instantiated, one -instantiates the @code{Ipv4Impl} class to create an @code{Ipv4} @code{Object}. -You will use the @code{CreateObject} template function to create an object that -implements the methods of an @code{Object}. You can probably see how this -gets even more tricky in conversation. - -Once the @code{Ipv4Impl} object is instantiated, the resulting pointer is -immediately cast to an @code{Ipv4} pointer. Clients will then use the -methods specified in the @code{Ipv4} class to access the @code{Ipv4 Object} -methods which are, in turn, implemented in the @code{Ipv4Impl} object. - -If you now look in the file, @code{src/internet-stack/internet-stack.cc} you -will see the following code in @code{InternetNode::Construct} that creates the -@code{Ipv4} Interface and aggregates it. - -@verbatim - Ptr ipv4Impl = CreateObject (ipv4); - ... - Object::AggregateObject (ipv4Impl); -@end verbatim - -Note that the parameter @code{ipv4} passed to the @code{CreateObject} template -function is actually a pointer to an @code{Ipv4L3Protocol} which you can -ignore at this point --- it doesn't really have anything to do with the -@code{Ipv4} Interface. - -This is exactly the same thing that is happening in the case of the -@code{InternetNode}. - -@verbatim - Ptr n = CreateObject (); -@end verbatim - -@cindex implementation object -@code{CreateObject} is being called to create an implementation object, -in this case @code{InternetNode}, which implements the methods of the -@code{Node Object}. It is the resulting @code{Node Object} which you would -use as the container and it is the @code{Node} class that you would use as -the template parameter when calling @code{GetObject}. In the same way, you -would @emph{not} want to do, - -@verbatim - Ptr ipv4 = node->GetObject (); -@end verbatim - -Rather you should understand that the @emph{proper} @code{Object} is the -@code{Ipv4} not the @code{Ipv4Impl} and do the following, - -@verbatim - Ptr ipv4 = node->GetObject (); -@end verbatim - -@cindex CreateObject -This does illustrate that the fact that whether an object created by -@code{CreateObject} is or is not an @code{Object} in the usual sense can be -quite well hidden if you are casually looking at the object creation code. -The designers of the system had long and involved discussions on this issue -and in the end decided that mnemonic aids such as Hungarian notation were a -stylistic thing and you should just refer to the system documentation to -determine what objects are @command{ns-3} @code{Objects} and what the APIs -of those @code{Objects} actually are (RTFM --- as in Read the Fine Manual, -of course). - -@cindex AggregateObject -@cindex Object -In the case of @code{Ipv4Impl}, you know that the class inherits somehow -from @code{Object} since there is a call to @code{AggregateObject} that -refers to an instance of an @code{Ipv4Impl}. You will have to go to -the header file @code{src/internet-stack/ipv4-impl.h} and find that -@code{Ipv4Impl} inherits from class @code{Ipv4}. You will then have go to -the file @code{src/node/ipv4.h} and see that it inherits from @code{Object} and -defines a @code{GetTypeId}. Thus the @code{Object} for which you can -@code{GetObject} is really the @code{Ipv4 Object}. - -Returning to some real @command{ns-3} example code, lets take a look at -@code{examples/simple-point-to-point.cc}. You will find the following -code in this file: - -@verbatim - Ptr n0 = CreateObject (); - ... - Ptr ipv4; - ipv4 = n0->GetObject (); - ipv4->SetDefaultRoute (Ipv4Address (``10.1.1.2''), 1); -@end verbatim - -@cindex InternetNode -@cindex Node -@cindex Object -@cindex GetObject -The first line creates an @code{InternetNode} implementation object and casts -the resulting smart pointer to a @code{Node} as we have discussed extensively. -The next line shown declares a smart pointer to an @code{Ipv4 Object}. We -then do a @code{GetObject} on the @code{Node} looking for the -@code{Ipv4 Object}. You know since you've read every line of this tutorial -in detail exactly how that @code{Ipv4 Object} got into every @code{Node}. You -know that the @code{GetObject} will return a smart pointer to its aggregated -@code{Ipv4} Interface. Once we have the @code{Ipv4} smart pointer, we simply -use it as if it were any other C++ object. The last line shows this by -setting the default route for the node. - -@section Caveats -There are a few things that you should remember but which may not be -immediately obvious. - -@subsection Ns-3 Objects are Associated with Classes not C++ objects -@cindex Object -@cindex GetObject -@cindex iterate -@cindex aggregation -@cindex GetNDevices -Okay, you can see some of the problems with the terminology popping up again. -We are reminding you that when you do a GetObject you are providing the key -to the lookup by giving a class name and not anything that is unique to a -C++ object. - -You cannot add more than one @code{Object} of a given type (class name) to an -aggregation. If you need to contain a number of @code{Objects} of the same -type in the same aggregation, you will need to provide a separate container -over which you can iterate. For example, the @code{Node} class provides -methods, - -@verbatim - uint32_t GetNDevices (void) const; - Ptr GetDevice (uint32_t index) const; -@end verbatim - -that are used iterate over the multiple @code{NetDevice} @code{Objects} -associated with it. - -@emph{Remember: Object types do not identify objects.} - -@subsection Dont use GetObject to Check Your Own Type. -@cindex GetObject -It is tempting to use @code{GetObject} as a form of runtime type -information. Dont do it. You have no control over what @emph{other} -object may be added to your aggregation. Someone else may have -appropriated (reimplemented) your type and aggregated themselves onto the -aggregation. - -Consider a socket factory implementation. Sockets can be either UDP sockets -or TCP sockets. A socket factory will have a generic @code{SocketFactory} -Object and either a UDP specific interface for setting UDP parameters or a -similar TCP-specific interface. - -Consider what might happen if you declared your socket factory as a partially -abstract base class, and then provided separate implementations for UDP and -TCP specific methods of this factory in separate concrete classes. Now -consider what might happen if you used @code{GetObject} in your base class -to determine if you were a UDP or a TCP factory. - -If a factory, say the UDP version, were not aggregated to any other -@code{Object}, the base class could @code{GetObject} on itself for the -UDP-specific class name. If the @code{GetObject} succeeded, it could then -infer that it was a UDP implementation and would then do any UDP-specific -tasks it could. [Experienced C++ folks are cringing about how -horrible this design is, but bear with me --- its a simple illustration of -a specific and perhaps not-too-obvious problem.] - -If another factory, say the TCP version, were not aggregated to any other -Interface, the base class could @code{GetObject} on itself for the UDP-specific -interface. If this failed, it could then infer that it had a TCP -implementation and would then do any TCP-specific tasks it could. - -Now, what happens when these two working objects are aggregated together by -some innocent end-user. Since the @code{Objects} are conceptually snapped -together, the TCP implementation would suddenly begin finding the UDP -Interface from the other class factory and think it was the UPD implementation. - -@emph{Objects should not be used as run-time type information.} - -@section Connecting the Dots -@cindex Object -@cindex GetObject -@cindex AggregateObject -@cindex GetTypeId -@cindex API -This may all sound very complicated to you if this is your first exposure to -these concepts. It may be annoying if I tell you that its really not as hard -as it sounds. Rest assured that if you take some time, look at and understand -the examples and write a little test code it will all come together for you. -Grep around the system for @code{AggregateObject} and @code{GetObject} and -take a look at how we have used them. This will also give you a good idea of -what our core @code{Objects} and associated APIs are. If you grep for -@code{GetTypeId} you will find most, if not all of the @code{Object} API -interface declarations in the system. The more you see this idiom in -use, the more comfortable you will be with the idea and the more you will see -how this addresses the weak base class, swiss army knife base class, and -fragile base class problems I explained at the beginning. - -As I alluded to earlier, the developers had long discussions regarding how to -make navigating the @code{Object} environment easier. The primary issue was -how we could make it easier to convey to you, the model writer, that an object -was an @code{Object}. We originally used similar terminology as Microsoft -COM and used QueryInterface instead of @code{GetObject}. One suggestion was -to adopt the convention that classes that implemented Interfaces must begin -with the letter I. Microsoft does this, as exemplified by the class IUnknown. -We also toyed with the idea of beginning our header files with ``i-'' as in -``i-ipv4.h.'' We considered forcing some structure on Interfaces with a pure -virtual class specification, the names of which begin with an I; and -corresponding implementations, the names of which begin with a C. This all -got out of hand fairly quickly. - -In the end we decided that we were really discussing issues of programming -style, and we really could not come up with a strong reason to impose any -particular solution. No matter what direction we took, we ended up with some -form of extra confusion or extra complexity somewhere in the system. The -resulting system is extremely flexible and easy to use. It is, unfortunately, -sometimes hard to document and talk about. - -@cindex Feynman -If it helps you to think in terms of Microsoft COM and Interfaces, by all means -do so, just be aware that even though @command{ns-3} @code{Objects} descend -from COM in some sense, there are subtle differences that may get you lost or -into trouble. So to paraphrase Feynman one more time, - -@quotation -``@command{Ns-3} @code{Objects} do not behave like COM Components, or Java -Beans, or CORBA objects, or clouds or weights on springs, or like anything -that you have ever seen --- they are @command{ns-3} components.'' -@end quotation - -Just get very familiar with the @command{ns-3} object model. It is the heart -of the system and if you do not understand it you will not understand how to -write an @command{ns-3} model properly. - -@c ======================================================================== -@c Doxygen -@c ======================================================================== - -@node The-Doxygen-Documentation-System -@chapter The Doxygen Documentation System - -@node How-To-Change-Things -@chapter How to Change Things - -@node How-To-Set-Default-Values -@chapter How to Set Default Values - -@node How-To-Write-A-New-Application -@chapter How to Write a New Application - diff --git a/doc/tutorial/in-process/output.texi b/doc/tutorial/in-process/output.texi deleted file mode 100644 index 7e3813c02..000000000 --- a/doc/tutorial/in-process/output.texi +++ /dev/null @@ -1,462 +0,0 @@ - -@c ======================================================================== -@c Simulation Output -@c ======================================================================== - -@node Simulation Output -@chapter Simulation Output - -At this point, you should be able to execute any of the built-in -programs distributed with @command{ns-3}. Next, we will look at -how to generate and tailor the simulation output, before turning -to how to modify simulation scripts to do different things. - -@node Tracing Basics -@section Tracing Basics - -The whole point of simulation is to generate output for further -study, and the @command{ns-3} tracing system is a primary -mechanism for this. -Since @command{ns-3} is a C++ program, standard facilities for -generating output from C++ programs apply: - -@verbatim -#include -... -int main () -{ - ... - std::cout << "The value of x is " << x << std::endl; - ... -} -@end verbatim - -The goal of the @command{ns-3} tracing system is to -provide a structured way to configure the simulator to output results -in standard or modifiable formats. -@itemize @bullet -@item For basic tasks, the tracing system should allow the user to -generate standard tracing for popular tracing sources, and to customize -which objects generate the tracing. -@item Intermediate users will be able to extend the tracing system to -modify the output format generated, or to insert new tracing sources, -without modifying the core of the simulator. -@item Advanced users can modify the simulator core to add new -tracing sources and sinks. -@end itemize - -The @command{ns-3} tracing system is fundamentally built on the -concept of separating tracing sources from sinks. -@enumerate -@item Trace sources (e.g., provide access to every packet received) -@item Trace sinks (e.g., print out the packet) -@item A mechanism to tie together sources and sinks -@end enumerate -The rationale for this division is to allow users to attach new -types of sinks to existing tracing sources, without requiring -users to edit and recompile the core of the simulator. -Thus, in the example above, a user could write a new tracing sink -and attach it to an existing tracing source. What remains to -be defined is a way for users to find these hooks (tracing sources) -and attach sinks to them. A new tracing namespace is defined for -this purpose. - -We will first walk through how some pre-defined sources and sinks -are provided and may be customized with little user effort. We -return later in this chapter to advanced tracing configuration including -extending the tracing namespace and creating new tracing sources. - -@subsection ASCII tracing -@cindex ASCII -For Internet nodes, the ASCII trace wrapper is a wrapper around -the @command{ns-3} low-level -tracing system that lets you get access to underlying trace events easily. -The output of a trace of a simulation run is an ASCII file --- thus the name. -In the spirit of keeping things simple, you won't be able to control or -configure the output at this stage. - -For those familiar with @command{ns-2} output, this type of trace is -analogous to the @command{out.tr} generated by many scripts. - -@cindex tracing packets -Let's just jump right in. As usual, we need to include the definitions -related to using ASCII tracing (don't edit any files quite yet): - -@verbatim - #include "ns3/ascii-trace.h" -@end verbatim - -We then need to add the code to the script to actually enable the ASCII tracing -code. The following code must be inserted before the call to -@code{Simulator::Run ();}: - -@verbatim - AsciiTrace asciitrace ("tutorial.tr"); - asciitrace.TraceAllQueues (); - asciitrace.TraceAllNetDeviceRx (); -@end verbatim - -The first line declares an object of type @code{AsciiTrace} named -@code{asciitrace} and passes a string parameter to its constructor. This -parameter is a file name to which all of the trace information will be written. -The second line, @code{asciitrace.TraceAllQueues ();} asks the trace object to -arrange that all queue operations (enqueue, dequeue, drop) on the queues -in all of the nodes of the system be traced. On the receive side, -@code{asciitrace.TraceAlllNetDeviceRx ()} traces packets received by -a NetDevice. For those familiar with @command{ns-2}, these are equivalent -to the popular trace points that log "+", "-", "d", and "r" events. - -Try running the following program from the command line: -@verbatim - ./waf --run tutorial-csma-echo-ascii-trace -@end verbatim - -@cindex tutorial.tr -Just as you have seen previously, you will see some messages from @emph{Waf} -and then the ``Compilation finished successfully'' message. The -next message, @code{UDP Echo Simulation} is from the running program. When -it ran, the program will have created a file named @code{tutorial.tr}. -Because of the way that Waf works, the file is not created in the local -directory, it is created at the top-level directory of the repository. So, -change into the top level directory and take a look at the file -@code{tutorial.tr} in your favorite editor. - -@subsubsection Parsing Ascii Traces -@cindex parsing ascii traces - -This section parses in detail the structure of the ascii tracing -output. If you find this output format self explanatory (it -resembles tcpdump output), you may skip to the next -section on pcap tracing. - -@cindex trace event -There's a lot of information there in a pretty dense form, but the first thing -to notice is that there are a number of distinct lines in this file. It may -be difficult to see this clearly unless you widen your windows considerably. -Each line in the file corresponds to a @emph{trace event}. A trace event -happens whenever specific conditions happen in the simulation. In this case -we are tracing events on the @emph{device queue} present in every net device -on every node in the simulation. The device queue is a queue through which -every packet destined for a channel must pass --- it is the device -@emph{transmit} queue. Note that each line in the trace file begins with a -lone character (has a space after it). This character will have the following -meaning: - -@cindex enqueue -@cindex dequeue -@cindex drop -@itemize @bullet -@item @code{+}: An enqueue operation occurred on the device queue; -@item @code{-}: A dequeue operation occurred on the device queue; -@item @code{d}: A packet was dropped, typically because the queue was full. -@end itemize - -Let's take a more detailed view of the first line. I'll break it down into -sections (indented for clarity) with a two digit reference number on the -left side: - -@verbatim - 00 + - 01 2 - 02 nodeid=0 - 03 device=0 - 04 queue-enqueue - 05 pkt-uid=9 - 06 ETHERNET - 07 length/type=0x806, - 08 source=08:00:2e:00:00:00, - 09 destination=ff:ff:ff:ff:ff:ff - 10 ARP(request - 11 source mac: 08:00:2e:00:00:00 - 12 source ipv4: 10.1.1.1 - 13 dest ipv4: 10.1.1.2) - 14 ETHERNET fcs=0 -@end verbatim - -@cindex trace event -@cindex simulation time -The first line of this expanded trace event (reference number 00) is the -queue operation. We have a @code{+} character, so this corresponds to an -@emph{enqueue} operation. The second line (reference 01) is the simulation -time expressed in seconds. You may recall that we asked the -@code{UdpEchoClient} to start sending packets at two seconds. Here we see -confirmation that this is, indeed, happening. - -@cindex node number -@cindex net device number -@cindex smart pointer -The next lines of the example listing (references 02 and 03) tell us that -this trace event originated in a given node and net device. Each time a node -is created it is given an identifying number that monotonically increases from -zero. Therefore, @code{nodeid=0} means that the node in which the given trace -event originated is the first node we created. In the case of our script, -this first node is is the node pointed to by the smart pointer @code{n0}. Not -too surprisingly, this is also the node to which we attached the -@code{UdpEchoClient}. The device number is local to each node, and so the -device given by @code{device=0} is the first net device that we added to the -node in question. In our simulation, this corresponds to the -@code{CsmaNetDevice} we added to node zero (@code{n0}). - -@cindex uid -@cindex unique ID -@cindex packet -The next line (reference 04) is a more readable form of the operation code -seen in the first line --- i.e., the character @code{+} means -@code{queue-enqueue}. Reference number 05 indicates that the @emph{unique id} -of the packet being enqueued is @code{9}. The fact that the first packet we -see has a unique ID of 9 should indicates to you that other things have -happened in the protocol stack before we got to this point. This will become -clear momentarily. - -@cindex Ethernet -@cindex MAC address -Reference items 06 and 14 indicate that this is an Ethernet packet with -a zero (not computed) checksum (note the indentation to make parsing this -trace event a little easier). Reference 08 and 09 are the source and -destination addresses of this packet. The packet is from the MAC address we -assigned to the node zero net device in the script, and is destined for the -broadcast address --- this is a broadcast packet. - -@cindex Address Resolution Protocol -@cindex ARP -@cindex ARP|request -Reference items 10 through 13 make clear what is happening. This is an ARP -(Address Resolution Protocol) request for the MAC address of the node on -which the @code{UdpEchoServer} resides. The protocol stack can't send a UDP -packet to be echoed until it knows (resolves) the MAC address; and this trace -event corresponds to an ARP request being queued for transmission to the local -network. The next line in the trace file (partially expanded), - -@verbatim - 00 - - 01 2 - 02 nodeid=0 - 03 device=0 - 04 queue-dequeue - 05 pkt-uid=9 - ... -@end verbatim - -shows the (same) ARP request packet being dequeued from the device queue by -the net device and (implicitly) being sent down the channel to the broadcast -MAC address. We are not tracing net device reception events so we don't -actually see all of the net devices receiving the broadcast packet. We do, -however see the following in the third line of the trace file: - -@verbatim - 00 + - 01 2.00207 - 02 nodeid=1 - 03 device=0 - 04 queue-enqueue - 05 pkt-uid=10 - 06 ETHERNET - 07 length/type=0x806, - 08 source=08:00:2e:00:00:01, - 09 destination=08:00:2e:00:00:00, - 10 ARP(reply - 11 source mac: 08:00:2e:00:00:01 - 12 source ipv4: 10.1.1.2 - 13 dest mac: 08:00:2e:00:00:00 - 14 dest ipv4: 10.1.1.1) - 15 ETHERNET fcs=0 -@end verbatim - -@cindex simulation time -@cindex ARP|response -Notice that this is a queue-enqueue operation (references 00 and 04) happening -on node one (reference 02) at simulation time 2.00207 seconds (reference 01). -Looking at the packet payload (references 10-14) we see that this is an ARP -reply to the request sent by node one. Note that the simulation time -(reference 01) is now 2.00207 seconds. This is direct result of the data rate -(5 mb/s) and latency (2 ms) parameters that we passed to the -@code{CsmaChannel} when we created it. Clearly the ARP request packet was -sent over the channel and received approximately 2 ms later by node one. A -corresponding ARP response packet was created and enqueued on node one's net -device. It is this enqueue trace event that has being logged. - -@cindex queue -@cindex queue|transmit -@cindex echo -Given the current state of affairs, the next thing you may expect to see is -this ARP request being received by node zero, but remember we are only looking -at trace events on the device @emph{transmit} queue. The reception of the ARP -response by node zero will not directly trigger any trace event in this case, -but it will enable the protocol stack to continue what it was originally doing -(trying to send an echo packet). Thus, the next line we see in the trace file -(@code{tutorial.tr}) is the first UDP echo packet being sent to the net device. - -@verbatim - 00 + - 01 2.00415 - 02 nodeid=0 - 03 device=0 - 04 queue-enqueue - 05 pkt-uid=7 - 06 ETHERNET - 07 length/type=0x800, - 08 source=08:00:2e:00:00:00, - 09 destination=08:00:2e:00:00:01 - 10 IPV4( - 11 tos 0x0 - 12 ttl 64 - 13 id 0 - 14 offset 0 - 15 flags [none] - 16 length: 1052) 10.1.1.1 > 10.1.1.2 - 17 UDP(length: 1032) - 18 49153 > 7 - 19 DATA (length 1024) - 20 ETHERNET fcs=0 -@end verbatim - -@cindex simulation time -@cindex echo -@cindex ARP -@cindex ARP|request -@cindex ARP|response -@cindex IP -@cindex Ipv4 -I won't go into too much detail about this packet, but I will point out a -few key items in the trace. First, the packet was enqueued at simulation time -of 2.00415 seconds. This time reflects the fact that the echo client -application started at 2. seconds and there were two ARP packets transmitted -across the network (two milliseconds + data transmission time each way). The -packet unique identifier (reference 05) is 7. Notice that this is a lower -number than the ARP request packet, which had a unique ID of 9. This tells -us that the UDP packet was actually created before the ARP request packet --- -which makes perfect sense since it was the attempt to send packet 7 that -triggered sending the ARP request packet 9. Note that this an Ethernet -packet (reference 06) like all other packets in this simulation, however this -particular packet carries an IPV4 payload and therefore has an IP version 4 -header (indicated by references 10-16). This Ipv4 in turn contains a UDP -header (references 17, 18) and finally 1024 bytes of data (reference 20). -Clearly, this is the UDP echo packet emitted by the -@code{UdpEchoClient Application}. - -The next trace event is an ARP request from node one. We can infer that node -one has received the UDP echo packet and the @code{UdpEchoServer Application} -on that node has turned the packet around. Just as node zero needed to ARP -for the MAC address of node one, now node one must ARP for the MAC address of -node zero. We see the ARP request enqueued on the transmit queue of node one; -then we see the ARP request dequeued from the transmit queue of node one (and -implicitly transmitted to node zero). Then we see an ARP response enqueued -on the transmit queue of node zero; and finally the ARP response dequeued (and -implicitly transmitted back to node one). - -This exchange is summarized in the following trace event excerpts, - -@verbatim - + 2.00786 nodeid=1 ... ARP(request ... - - 2.00786 nodeid=1 ... ARP(request ... - + 2.00994 nodeid=0 ... ARP(reply ... - - 2.00994 nodeid=0 ... ARP(reply ... -@end verbatim - -The final two trace events in the @code{tutorial.tr} file correspond to the -echoed packet being enqueued for transmission on the net device for node one, -and that packet being dequeued (and implicitly transmitted back to node zero). - -@cindex AsciiTrace!TraceAllNetDeviceRx -@cindex ARP!request -If you look at the trace file (@code{tutorial.tr}) you will also see some -entries with an @code{r} event, indicating a -@emph{receive} trace event. Recall that the first packet sent on the network -was a broadcast ARP request. We should then see all four nodes receive a -copy of this request. This is the case, as the first four receive trace -events are, - -@verbatim - r 2.00207 nodeid=0 device=0 dev-rx pkt-uid=9 ARP(request ... - r 2.00207 nodeid=1 device=0 dev-rx pkt-uid=9 ARP(request ... - r 2.00207 nodeid=2 device=0 dev-rx pkt-uid=9 ARP(request ... - r 2.00207 nodeid=3 device=0 dev-rx pkt-uid=9 ARP(request ... -@end verbatim - -@cindex unique ID -You can see that a copy of the broadcast packet with unique ID 9 was received -by the net devices on nodes 0, 1, 2 and 3. We leave it up to you to parse the -rest of the trace file and understand the remaining reception events. - -@subsection PCAP Trace Wrapper -@cindex pcap -@cindex Wireshark -The @command{ns-3} @emph{pcap trace wrapper} is used to create trace files in -@code{.pcap} format. The acronym pcap (usually written in lower case) stands -for @emph{p}acket @emph{cap}ture, and is actually an API that includes the -definition of a @code{.pcap} file format. The most popular program that can -read and display this format is Wireshark (formerly called Ethereal). -However, there are many traffic trace analyzers that use this packet -format, including X, Y, and Z. We encourage users to exploit the -many tools available for analyzing pcap traces; below, we show how -tcpdump and Wireshark can be used.. - -@cindex tutorial-csma-echo-ascii-trace.cc -@cindex tutorial-csma-echo-pcap-trace.cc -The code used to enable pcap tracing is similar to that for ASCII tracing. -We have provided another file, @code{tutorial-csma-echo-pcap-trace.cc} that -uses the pcap trace wrapper. We have added the code to include the pcap -trace wrapper definitions: - -@verbatim - #include "ns3/pcap-trace.h" -@end verbatim - -And then added the following code below the AsciiTrace methods: - -@cindex PcapTrace -@cindex PcapTrace!TraceAllIp -@verbatim - PcapTrace pcaptrace ("tutorial.pcap"); - pcaptrace.TraceAllIp (); -@end verbatim - -The first line of the code immediately above declares an object of type -@code{PcapTrace} named @code{pcaptrace} and passes a string parameter to its -constructor. This object is used to hide the details of the actual tracing -subsystem. The parameter is a base file name from which the actual trace file -names will be built. The second line of code tells the @code{PcamTrace} -object to trace all IP activity in all of the nodes present in the simulation. - -@cindex interface index -Trace files are not created until trace activity is detected. Each file name -is composed of the base file name, followed by a @code{'-'}, a node id followed -by a @code{'-}', and an IP interface index. You will soon see a file named -@code{tutorial.pcap-0-1}, for example. This will be the trace file generated -as events are detected on node zero, interface index one. N.B. Interface -indices are different that net device indices --- interface index zero -corresponds to the loopback interface and interface index one corresponds to -the first net device you added to a node. - -You may run the new program just like all of the others so far: - -@cindex Waf -@verbatim - ./waf --run tutorial-csma-echo-pcap-trace -@end verbatim - -If you look at the top level directory of your distribution, you should now -see three log files: @code{tutorial.tr} is the ASCII trace file we have -previously examined. @code{tutorial.pcap-0-1} and @code{tutorial.pcap-1-1} -are the new pcap files we just generated. There will not be files -corresponding to nodes two and three since we have not sent any IP packets to -those nodes. - -@subsubsection Reading output with tcpdump -@cindex tcpdump - -@subsubsection Reading output with Wireshark -@cindex Wireshark -If you are unfamiliar with Wireshark, there is a web site available from which -you can download programs and documentation: @uref{http://www.wireshark.org/}. - -If you have Wireshark available, you can open each of the trace files and -display the contents as if you had captured the packets using a -@emph{packet sniffer}. Note that only IP packets are traced using this -wrapper, so you will not see the ARP exchanges that were logged when using -the ASCII trace wrapper. You are encouraged to take a look at the contents -of these pcap files using your favorite pcap software (or Wireshark). - -@node Advanced Tracing -@section Advanced Tracing - diff --git a/doc/tutorial/in-process/statistics.texi b/doc/tutorial/in-process/statistics.texi deleted file mode 100644 index 094e91a4b..000000000 --- a/doc/tutorial/in-process/statistics.texi +++ /dev/null @@ -1,9 +0,0 @@ -@node Statistics -@chapter Statistics -@anchor{chap:Statistics} - -ns-3 does not presently have support for statistics (automatically generated -statistical output). This is planned -for development later in 2008. If you are interested in contributing, -please see @uref{http://www.nsnam.org/wiki/index.php/Suggested_Projects,,our suggested projects page} or contact the ns-developers -list. diff --git a/doc/tutorial/in-process/troubleshoot.texi b/doc/tutorial/in-process/troubleshoot.texi deleted file mode 100644 index 6ac901d15..000000000 --- a/doc/tutorial/in-process/troubleshoot.texi +++ /dev/null @@ -1,82 +0,0 @@ -@node Troubleshooting -@chapter Troubleshooting - -This chapter posts some information about possibly common errors in building -or running ns-3 programs. - -Please note that the wiki (@uref{http://www.nsnam.org/wiki/index.php/Troubleshooting}) may have contributed items. - -@node Build errors -@section Build errors - -@node Run-time errors -@section Run-time errors - -Sometimes, errors can occur with a program after a successful build. These -are run-time errors, and can commonly occur when memory is corrupted or -pointer values are unexpectedly null. - -Here is an example of what might occur: - -@verbatim -ns-old:~/ns-3-nsc$ ./waf --run tcp-point-to-point -Entering directory `/home/tomh/ns-3-nsc/build' -Compilation finished successfully -Command ['/home/tomh/ns-3-nsc/build/debug/examples/tcp-point-to-point'] exited with code -11 -@end verbatim - -The error message says that the program terminated unsuccessfully, but it is -not clear from this information what might be wrong. To examine more -closely, try running it under the @uref{http://sources.redhat.com/gdb/,,gdb debugger}: - -@verbatim -ns-old:~/ns-3-nsc$ ./waf --run tcp-point-to-point --command-template="gdb %s" -Entering directory `/home/tomh/ns-3-nsc/build' -Compilation finished successfully -GNU gdb Red Hat Linux (6.3.0.0-1.134.fc5rh) -Copyright 2004 Free Software Foundation, Inc. -GDB is free software, covered by the GNU General Public License, and you are -welcome to change it and/or distribute copies of it under certain conditions. -Type "show copying" to see the conditions. -There is absolutely no warranty for GDB. Type "show warranty" for details. -This GDB was configured as "i386-redhat-linux-gnu"...Using host libthread_db library "/lib/libthread_db.so.1". - -(gdb) run -Starting program: /home/tomh/ns-3-nsc/build/debug/examples/tcp-point-to-point -Reading symbols from shared object read from target memory...done. -Loaded system supplied DSO at 0xf5c000 - -Program received signal SIGSEGV, Segmentation fault. -0x0804aa12 in main (argc=1, argv=0xbfdfefa4) - at ../examples/tcp-point-to-point.cc:136 -136 Ptr localSocket = socketFactory->CreateSocket (); -(gdb) p localSocket -$1 = {m_ptr = 0x3c5d65} -(gdb) p socketFactory -$2 = {m_ptr = 0x0} -(gdb) quit -The program is running. Exit anyway? (y or n) y -@end verbatim - -Note first the way the program was invoked-- pass the command to run as -an argument to the command template "gdb %s". - -This tells us that there was an attempt to dereference a null pointer -socketFactory. - -Let's look around line 136 of tcp-point-to-point, as gdb suggests: -@verbatim - Ptr socketFactory = n2->GetObject (Tcp::iid); - Ptr localSocket = socketFactory->CreateSocket (); - localSocket->Bind (); -@end verbatim - -The culprit here is that the return value of GetObject is not being -checked and may be null. - -Sometimes you may need to use the @uref{http://valgrind.org,,valgrind memory -checker} for more subtle errors. Again, you invoke the use of valgrind -similarly: -@verbatim -ns-old:~/ns-3-nsc$ ./waf --run tcp-point-to-point --command-template="valgrind %s" -@end verbatim diff --git a/doc/tutorial/in-process/tutorial.css b/doc/tutorial/in-process/tutorial.css deleted file mode 100644 index a7586ac83..000000000 --- a/doc/tutorial/in-process/tutorial.css +++ /dev/null @@ -1,156 +0,0 @@ -body { - font-family: "Trebuchet MS", "Bitstream Vera Sans", verdana, lucida, arial, helvetica, sans-serif; - background: white; - color: black; - font-size: 11pt; -} - -h1, h2, h3, h4, h5, h6 { -# color: #990000; - color: #009999; -} - -pre { - font-size: 10pt; - background: #e0e0e0; - color: black; -} - -a:link, a:visited { - font-weight: normal; - text-decoration: none; - color: #0047b9; -} - -a:hover { - font-weight: normal; - text-decoration: underline; - color: #0047b9; -} - -img { - border: 0px; -} - -#main th { - font-size: 12pt; - background: #b0b0b0; -} - -.odd { - font-size: 12pt; - background: white; -} - -.even { - font-size: 12pt; - background: #e0e0e0; -} - -.answer { - font-size: large; - font-weight: bold; -} - -.answer p { - font-size: 12pt; - font-weight: normal; -} - -.answer ul { - font-size: 12pt; - font-weight: normal; -} - -#container { - position: absolute; - width: 100%; - height: 100%; - top: 0px; -} - -#feedback { - color: #b0b0b0; - font-size: 9pt; - font-style: italic; -} - -#header { - position: absolute; - margin: 0px; - top: 10px; - height:96px; - left: 175px; - right: 10em; - bottom: auto; - background: white; - clear: both; -} - -#middle { - position: absolute; - left: 0; - height: auto; - width: 100%; -} - -#main { - position: absolute; - top: 50px; - left: 175px; - right: 100px; - background: white; - padding: 0em 0em 0em 0em; -} - -#navbar { - position: absolute; - top: 75px; - left: 0em; - width: 146px; - padding: 0px; - margin: 0px; - font-size: 10pt; -} - -#navbar a:link, #navbar a:visited { - font-weight: normal; - text-decoration: none; - color: #0047b9; -} - -#navbar a:hover { - font-weight: normal; - text-decoration: underline; - color: #0047b9; -} - -#navbar dl { - width: 146px; - padding: 0; - margin: 0 0 10px 0px; - background: #99ffff url(images/box_bottom2.gif) no-repeat bottom left; -} - -#navbar dt { - padding: 6px 10px; - font-size: 100%; - font-weight: bold; - background: #009999; - margin: 0px; - border-bottom: 1px solid #fff; - color: white; - background: #009999 url(images/box_top2.gif) no-repeat top left; -} - -#navbar dd { - font-size: 100%; - margin: 0 0 0 0px; - padding: 6px 10px; - color: #0047b9; -} - -dd#selected { - background: #99ffff url(images/arrow.gif) no-repeat; - background-position: 4px 10px; -} diff --git a/doc/tutorial/in-process/tutorial.texi b/doc/tutorial/in-process/tutorial.texi deleted file mode 100644 index d2e7a4813..000000000 --- a/doc/tutorial/in-process/tutorial.texi +++ /dev/null @@ -1,105 +0,0 @@ -\input texinfo @c -*-texinfo-*- -@c %**start of header -@setfilename ns-3.info -@settitle ns-3 tutorial -@c @setchapternewpage odd -@c %**end of header - -@ifinfo -Primary documentation for the @command{ns-3} project is available in -three forms: -@itemize @bullet -@item @uref{http://www.nsnam.org/doxygen/index.html,,ns-3 Doxygen/Manual}: Documentation of the public APIs of the simulator -@item Tutorial (this document) -@item @uref{http://www.nsnam.org/wiki/index.php,, ns-3 wiki} -@end itemize - -This document is written in GNU Texinfo and is to be maintained in -revision control on the @command{ns-3} code server. Both PDF and HTML versions -should be available on the server. Changes to -the document should be discussed on the ns-developers@@isi.edu mailing list. -@end ifinfo - -@copying - -This is an @command{ns-3} tutorial. -Primary documentation for the @command{ns-3} project is available in -three forms: -@itemize @bullet -@item @uref{http://www.nsnam.org/doxygen/index.html,,ns-3 Doxygen/Manual}: Documentation of the public APIs of the simulator -@item Tutorial (this document) -@item @uref{http://www.nsnam.org/wiki/index.php,, ns-3 wiki} -@end itemize - -This document is written in GNU Texinfo and is to be maintained in -revision control on the @command{ns-3} code server. Both PDF and HTML -versions should be available on the server. Changes to -the document should be discussed on the ns-developers@@isi.edu mailing list. - -This software is free software; you can redistribute it and/or modify -it under the terms of the GNU General Public License as published by -the Free Software Foundation; either version 2 of the License, or -(at your option) any later version. - -This software is distributed in the hope that it will be useful, -but WITHOUT ANY WARRANTY; without even the implied warranty of -MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -GNU General Public License for more details. - -You should have received a copy of the GNU General Public License -along with this program. If not, see @uref{http://www.gnu.org/licenses/}. -@end copying - -@titlepage -@title ns-3 Tutorial -@author ns-3 project -@author feedback: ns-developers@@isi.edu -@today{} - -@c @page -@vskip 0pt plus 1filll -@insertcopying -@end titlepage - -@c So the toc is printed at the start. -@anchor{Full Table of Contents} -@contents - -@ifnottex -@node Top, Overview, Full Table of Contents -@top ns-3 Tutorial (html version) - -For a pdf version of this tutorial, -see @uref{http://www.nsnam.org/docs/tutorial.pdf}. - -@insertcopying -@end ifnottex - -@menu -* Tutorial Goals:: -Part 1: Getting Started with ns-3 -* Overview:: -* Browsing:: -* Resources:: -* Downloading and Compiling:: -* Some-Prerequisites:: -Part 2: Reading ns-3 Programs -* A-First-ns-3-Script:: -Part 3: Reconfiguring Existing ns-3 Scripts -* Logging:: -* ns-3 Attributes:: -* Tracing:: -* Statistics:: -Part 4: Creating New or Revised Topologies -* Helper Functions:: -@end menu - -@include introduction.texi -@include log.texi -@include attributes.texi -@include statistics.texi -@include helpers.texi - -@printindex cp - -@bye diff --git a/doc/tutorial/introduction.texi b/doc/tutorial/introduction.texi deleted file mode 100644 index 64c5b7673..000000000 --- a/doc/tutorial/introduction.texi +++ /dev/null @@ -1,310 +0,0 @@ - -@c ======================================================================== -@c Begin document body here -@c ======================================================================== - -@c ======================================================================== -@c PART: Introduction -@c ======================================================================== -@c The below chapters are under the major heading "Introduction" -@c This is similar to the Latex \part command -@c -@c ======================================================================== -@c Introduction -@c ======================================================================== -@node Introduction -@chapter Introduction - -@menu -* For ns-2 Users:: -* Contributing:: -* Tutorial Organization:: -@end menu - -The @command{ns-3} simulator is a discrete-event network simulator targeted -primarily for research and educational use. The -@uref{http://www.nsnam.org,,ns-3 project}, -started in 2006, is an open-source project developing @command{ns-3}. - -Primary documentation for the @command{ns-3} project is available in four -forms: -@itemize @bullet -@item @uref{http://www.nsnam.org/doxygen/index.html,,ns-3 Doxygen/Manual}: -Documentation of the public APIs of the simulator -@item Tutorial (this document) -@item @uref{http://www.nsnam.org/docs/manual.html,,Reference Manual}: Reference Manual -@item @uref{http://www.nsnam.org/wiki/index.php,, ns-3 wiki} -@end itemize - -The purpose of this tutorial is to introduce new @command{ns-3} users to the -system in a structured way. It is sometimes difficult for new users to -glean essential information from detailed manuals and to convert this -information into working simulations. In this tutorial, we will build -several example simulations, introducing and explaining key concepts and -features as we go. - -As the tutorial unfolds, we will introduce the full @command{ns-3} documentation -and provide pointers to source code for those interested in delving deeper -into the workings of the system. - -A few key points are worth noting at the onset: -@itemize @bullet -@item Ns-3 is not an extension of @uref{http://www.isi.edu/nsnam/ns,,ns-2}; -it is a new simulator. The two simulators are both written in C++ but -@command{ns-3} is a new simulator that does not support the ns-2 APIs. Some -models from ns-2 have already been ported from ns-2 to @command{ns-3}. The -project will continue to maintain ns-2 while @command{ns-3} is being built, -and will study transition and integration mechanisms. -@item @command{Ns-3} is open-source, and the project strives to maintain an -open environment for researchers to contribute and share their software. -@end itemize - -@node For ns-2 Users -@section For ns-2 Users - -For those familiar with ns-2, the most visible outward change when moving to -@command{ns-3} is the choice of scripting language. Ns-2 is -scripted in OTcl and results of simulations can be visualized using the -Network Animator @command{nam}. It is not possible to run a simulation -in ns-2 purely from C++ (i.e., as a main() program without any OTcl). -Moreover, some components of ns-2 are written in C++ and others in OTcl. -In @command{ns-3}, the simulator is written entirely in C++, with optional -Python bindings. Simulation scripts can therefore be written in C++ -or in Python. The results of some simulations can be visualized by -@command{nam}, but new animators are under development. Since @command{ns-3} -generates pcap packet trace files, other utilities can be used to -analyze traces as well. -In this tutorial, we will first concentrate on scripting -directly in C++ and interpreting results via trace files. - -But there are similarities as well (both, for example, are based on C++ -objects, and some code from ns-2 has already been ported to @command{ns-3}). -We will try to highlight differences between ns-2 and @command{ns-3} -as we proceed in this tutorial. - -A question that we often hear is "Should I still use ns-2 or move to -@command{ns-3}?" The answer is that it depends. @command{ns-3} does not have -all of the models that ns-2 currently has, but on the other hand, @command{ns-3} -does have new capabilities (such as handling multiple interfaces on nodes -correctly, use of IP addressing and more alignment with Internet -protocols and designs, more detailed 802.11 models, etc.). ns-2 -models can usually be ported to @command{ns-3} (a porting guide is under -development). There is active development on multiple fronts for -@command{ns-3}. The @command{ns-3} developers believe (and certain early users -have proven) that @command{ns-3} is ready for active use, and should be an -attractive alternative for users looking to start new simulation projects. - -@node Contributing -@section Contributing - -@cindex contributing -@command{Ns-3} is a research and educational simulator, by and for the -research community. It will rely on the ongoing contributions of the -community to develop new models, debug or maintain existing ones, and share -results. There are a few policies that we hope will encourage people to -contribute to @command{ns-3} like they have for ns-2: -@itemize @bullet -@item Open source licensing based on GNU GPLv2 compatibility; -@item @uref{http://www.nsnam.org/wiki/index.php,,wiki}; -@item @uref{http://www.nsnam.org/wiki/index.php/Contributed_Code,,Contributed Code} page, similar to ns-2's popular -@uref{http://nsnam.isi.edu/nsnam/index.php/Contributed_Code,,Contributed Code} -page; -@item @code{src/contrib} directory (we will host your contributed code); -@item Open @uref{http://www.nsnam.org/bugzilla,,bug tracker}; -@item @command{Ns-3} developers will gladly help potential contributors to get -started with the simulator (please contact @uref{http://www.nsnam.org/people.html,,one of us}). -@end itemize - -We realize that if you are reading this document, contributing back to -the project is probably not your foremost concern at this point, but -we want you to be aware that contributing is in the spirit of the project and -that even the act of dropping us a note about your early experience -with @command{ns-3} (e.g. "this tutorial section was not clear..."), -reports of stale documentation, etc. are much appreciated. - -@node Tutorial Organization -@section Tutorial Organization - -The tutorial assumes that new users might initially follow a path such as the -following: - -@itemize @bullet -@item Try to download and build a copy; -@item Try to run a few sample programs; -@item Look at simulation output, and try to adjust it. -@end itemize - -As a result, we have tried to organize the tutorial along the above -broad sequences of events. - -@c ======================================================================== -@c Resources -@c ======================================================================== - -@node Resources -@chapter Resources - -@menu -* The Web:: -* Mercurial:: -* Waf:: -* Development Environment:: -* Socket Programming:: -@end menu - -@node The Web -@section The Web - -@cindex www.nsnam.org -@cindex documentation -@cindex architecture -There are several important resources of which any @command{ns-3} user must be -aware. The main web site is located at @uref{http://www.nsnam.org} and -provides access to basic information about the @command{ns-3} system. Detailed -documentation is available through the main web site at -@uref{http://www.nsnam.org/documents.html}. You can also find documents -relating to the system architecture from this page. - -There is a Wiki that complements the main @command{ns-3} web site which you will -find at @uref{http://www.nsnam.org/wiki/}. You will find user and developer -FAQs there, as well as troubleshooting guides, third-party contributed code, -papers, etc. - -@cindex mercurial repository -@cindex ns-3-dev repository -@cindex release repository -The source code may be found and browsed at @uref{http://code.nsnam.org/}. -There you will find the current development tree in the repository named -@code{ns-3-dev}. Past releases and experimental repositories of the core -developers may also be found there. - -@node Mercurial -@section Mercurial - -Complex software systems need some way to manage the organization and -changes to the underlying code and documentation. There are many ways to -perform this feat, and you may have heard of some of the systems that are -currently used to do this. The Concurrent Version System (CVS) is probably -the most well known. - -@cindex software configuration management -@cindex Mercurial -The @command{ns-3} project uses Mercurial as its source code management system. -Although you do not need to know much about Mercurial in order to complete -this tutorial, we recommend becoming familiar with Mercurial and using it -to access the source code. Mercurial has a web site at -@uref{http://www.selenic.com/mercurial/}, -from which you can get binary or source releases of this Software -Configuration Management (SCM) system. Selenic (the developer of Mercurial) -also provides a tutorial at -@uref{http://www.selenic.com/mercurial/wiki/index.cgi/Tutorial/}, -and a QuickStart guide at -@uref{http://www.selenic.com/mercurial/wiki/index.cgi/QuickStart/}. - -You can also find vital information about using Mercurial and @command{ns-3} -on the main @command{ns-3} web site. - -@node Waf -@section Waf - -@cindex Waf -@cindex make -@cindex build -Once you have source code downloaded to your local system, you will need -to compile that source to produce usable programs. Just as in the case of -source code management, there are many tools available to perform this -function. Probably the most well known of these tools is @code{make}. Along -with being the most well known, @code{make} is probably the most difficult to -use in a very large and highly configurable system. Because of this, many -alternatives have been developed. Recently these systems have been developed -using the Python language. - -The build system @code{Waf} is used on the @command{ns-3} project. It is one -of the new generation of Python-based build systems. You will not need to -understand any Python to build the existing @command{ns-3} system, and will -only have to understand a tiny and intuitively obvious subset of Python in -order to extend the system in most cases. - -For those interested in the gory details of Waf, the main web site can be -found at @uref{http://code.google.com/p/waf/}. - -@node Development Environment -@section Development Environment - -@cindex C++ -@cindex Python -As mentioned above, scripting in @command{ns-3} is done in C++ or Python. -As of ns-3.2, most of the @command{ns-3} API is available in Python, but the -models are written in C++ in either case. A working -knowledge of C++ and object-oriented concepts is assumed in this document. -We will take some time to review some of the more advanced concepts or -possibly unfamiliar language features, idioms and design patterns as they -appear. We don't want this tutorial to devolve into a C++ tutorial, though, -so we do expect a basic command of the language. There are an almost -unimaginable number of sources of information on C++ available on the web or -in print. - -If you are new to C++, you may want to find a tutorial- or cookbook-based -book or web site and work through at least the basic features of the language -before proceeding. For instance, -@uref{http://www.cplusplus.com/doc/tutorial/,,this tutorial}. - -@cindex toolchain -@cindex GNU -The @command{ns-3} system uses several components of the GNU ``toolchain'' -for development. A -software toolchain is the set of programming tools available in the given -environment. For a quick review of what is included in the GNU toolchain see, -@uref{http://en.wikipedia.org/wiki/GNU_toolchain}. @command{ns-3} uses gcc, -GNU binutils, and gdb. However, we do not use the GNU build system tools, -neither make nor autotools. We use Waf for these functions. - -@cindex Linux -Typically an @command{ns-3} author will work in Linux or a Linux-like -environment. For those running under Windows, there do exist environments -which simulate the Linux environment to various degrees. The @command{ns-3} -project supports development in the Cygwin environment for -these users. See @uref{http://www.cygwin.com/} -for details on downloading (MinGW is presently not officially supported, -although some of the project maintainers to work with it). Cygwin provides -many of the popular Linux system commands. It can, however, sometimes be -problematic due to the way it actually does its emulation, and sometimes -interactions with other Windows software can cause problems. - -@cindex Cygwin -@cindex MinGW -If you do use Cygwin or MinGW; and use Logitech products, we will save you -quite a bit of heartburn right off the bat and encourage you to take a look -at the @uref{http://oldwiki.mingw.org/index.php/FAQ,,MinGW FAQ}. - -@cindex Logitech -Search for ``Logitech'' and read the FAQ entry, ``why does make often -crash creating a sh.exe.stackdump file when I try to compile my source code.'' -Believe it or not, the @code{Logitech Process Monitor} insinuates itself into -every DLL in the system when it is running. It can cause your Cygwin or -MinGW DLLs to die in mysterious ways and often prevents debuggers from -running. Beware of Logitech software when using Cygwin. - -Another alternative to Cygwin is to install a virtual machine environment -such as VMware server and install a Linux virtual machine. - -@node Socket Programming -@section Socket Programming - -@cindex sockets -We will assume a basic facility with the Berkeley Sockets API in the examples -used in this tutorial. If you are new to sockets, we recommend reviewing the -API and some common usage cases. For a good overview of programming TCP/IP -sockets we recommend @uref{http://www.elsevier.com/wps/find/bookdescription.cws_home/717656/description#description,,TCP/IP Sockets in C, Donahoo and Calvert}. - -There is an associated web site that includes source for the examples in the -book, which you can find at: -@uref{http://cs.baylor.edu/~donahoo/practical/CSockets/}. - -If you understand the first four chapters of the book (or for those who do -not have access to a copy of the book, the echo clients and servers shown in -the website above) you will be in good shape to understand the tutorial. -There is a similar book on Multicast Sockets, -@uref{http://www.elsevier.com/wps/find/bookdescription.cws_home/700736/description#description,,Multicast Sockets, Makofske and Almeroth}. -that covers material you may need to understand if you look at the multicast -examples in the distribution. diff --git a/doc/tutorial/pickle-to-xml.py b/doc/tutorial/pickle-to-xml.py new file mode 100755 index 000000000..be3126cf6 --- /dev/null +++ b/doc/tutorial/pickle-to-xml.py @@ -0,0 +1,42 @@ +#!/usr/bin/python + + +# output xml format: +# +# zzzlllfile.frag +# ... +# + +import pickle +import os +import codecs + +def dump_pickles(out, dirname, filename, path): + f = open(os.path.join(dirname, filename), 'r') + data = pickle.load(f) + fragment_file = codecs.open(data['current_page_name'] + '.frag', mode='w', encoding='utf-8') + fragment_file.write(data['body']) + fragment_file.close() + out.write(' \n' % path) + out.write(' %s.frag\n' % data['current_page_name']) + if data['prev'] is not None: + out.write(' %s\n' % + (os.path.normpath(os.path.join(path, data['prev']['link'])), + data['prev']['title'])) + if data['next'] is not None: + out.write(' %s\n' % + (os.path.normpath(os.path.join(path, data['next']['link'])), + data['next']['title'])) + out.write(' \n') + f.close() + if data['next'] is not None: + next_path = os.path.normpath(os.path.join(path, data['next']['link'])) + next_filename = os.path.basename(next_path) + '.fpickle' + dump_pickles(out, dirname, next_filename, next_path) + return + +import sys + +sys.stdout.write('\n') +dump_pickles(sys.stdout, os.path.dirname(sys.argv[1]), os.path.basename(sys.argv[1]), '/') +sys.stdout.write('') diff --git a/doc/tutorial/building-topologies.texi b/doc/tutorial/source/building-topologies.rst similarity index 68% rename from doc/tutorial/building-topologies.texi rename to doc/tutorial/source/building-topologies.rst index aa61ca610..71b8d4275 100644 --- a/doc/tutorial/building-topologies.texi +++ b/doc/tutorial/source/building-topologies.rst @@ -1,41 +1,20 @@ +.. include:: replace.txt -@c ======================================================================== -@c Begin document body here -@c ======================================================================== -@c ======================================================================== -@c PART: Building Topologies -@c ======================================================================== -@c The below chapters are under the major heading "Building Topologies" -@c This is similar to the Latex \part command -@c -@c ======================================================================== -@c Building Topologies -@c ======================================================================== -@node Building Topologies -@chapter Building Topologies +Building Topologies +------------------- -@menu -* Building a Bus Network Topology:: -* Building a Wireless Network Topology:: -@end menu +Building a Bus Network Topology +******************************* -@c ======================================================================== -@c Building a Bus Network Topology -@c ======================================================================== -@node Building a Bus Network Topology -@section Building a Bus Network Topology - -@cindex topology -@cindex bus network topology -In this section we are going to expand our mastery of @command{ns-3} network -devices and channels to cover an example of a bus network. @command{Ns-3} +In this section we are going to expand our mastery of |ns3| network +devices and channels to cover an example of a bus network. |ns3| provides a net device and channel we call CSMA (Carrier Sense Multiple Access). -The @command{ns-3} CSMA device models a simple network in the spirit of +The |ns3| CSMA device models a simple network in the spirit of Ethernet. A real Ethernet uses CSMA/CD (Carrier Sense Multiple Access with Collision Detection) scheme with exponentially increasing backoff to contend -for the shared transmission medium. The @command{ns-3} CSMA device and +for the shared transmission medium. The |ns3| CSMA device and channel models only a subset of this. Just as we have seen point-to-point topology helper objects when constructing @@ -43,39 +22,40 @@ point-to-point topologies, we will see equivalent CSMA topology helpers in this section. The appearance and operation of these helpers should look quite familiar to you. -We provide an example script in our @code{examples/tutorial} directory. This script -builds on the @code{first.cc} script and adds a CSMA network to the +We provide an example script in our examples/tutorial} directory. This script +builds on the ``first.cc`` script and adds a CSMA network to the point-to-point simulation we've already considered. Go ahead and open -@code{examples/tutorial/second.cc} in your favorite editor. You will have already seen -enough @command{ns-3} code to understand most of what is going on in this +``examples/tutorial/second.cc`` in your favorite editor. You will have already seen +enough |ns3| code to understand most of what is going on in this example, but we will go over the entire script and examine some of the output. -Just as in the @code{first.cc} example (and in all ns-3 examples) the file +Just as in the ``first.cc`` example (and in all ns-3 examples) the file begins with an emacs mode line and some GPL boilerplate. The actual code begins by loading module include files just as was done in the -@code{first.cc} example. +``first.cc`` example. + +:: -@verbatim #include "ns3/core-module.h" #include "ns3/simulator-module.h" #include "ns3/node-module.h" #include "ns3/helper-module.h" -@end verbatim One thing that can be surprisingly useful is a small bit of ASCII art that shows a cartoon of the network topology constructed in the example. You will -find a similar ``drawing'' in most of our examples. +find a similar "drawing" in most of our examples. In this case, you can see that we are going to extend our point-to-point example (the link between the nodes n0 and n1 below) by hanging a bus network off of the right side. Notice that this is the default network topology since you can actually vary the number of nodes created on the LAN. If you set nCsma to one, there will be a total of two nodes on the LAN (CSMA -channel) --- one required node and one ``extra'' node. By default there are -three ``extra'' nodes as seen below: +channel) --- one required node and one "extra" node. By default there are +three "extra" nodes as seen below: + +:: -@verbatim // Default Network Topology // // 10.1.1.0 @@ -83,20 +63,19 @@ three ``extra'' nodes as seen below: // point-to-point | | | | // ================ // LAN 10.1.2.0 -@end verbatim -Then the ns-3 namespace is @code{used} and a logging component is defined. -This is all just as it was in @code{first.cc}, so there is nothing new yet. +Then the ns-3 namespace is ``used`` and a logging component is defined. +This is all just as it was in ``first.cc``, so there is nothing new yet. -@verbatim +:: + using namespace ns3; NS_LOG_COMPONENT_DEFINE ("SecondScriptExample"); -@end verbatim The main program begins with a slightly different twist. We use a verbose -flag to determine whether or not the @code{UdpEchoClientApplication} and -@code{UdpEchoServerApplication} logging components are enabled. This flag +flag to determine whether or not the ``UdpEchoClientApplication`` and +``UdpEchoServerApplication`` logging components are enabled. This flag defaults to true (the logging components are enabled) but allows us to turn off logging during regression testing of this example. @@ -104,129 +83,129 @@ You will see some familiar code that will allow you to change the number of devices on the CSMA network via command line argument. We did something similar when we allowed the number of packets sent to be changed in the section on command line arguments. The last line makes sure you have at least one -``extra'' node. +"extra" node. The code consists of variations of previously covered API so you should be entirely comfortable with the following code at this point in the tutorial. -@verbatim +:: + bool verbose = true; uint32_t nCsma = 3; CommandLine cmd; - cmd.AddValue (``nCsma'', ``Number of \"extra\" CSMA nodes/devices'', nCsma); - cmd.AddValue (``verbose'', ``Tell echo applications to log if true'', verbose); + cmd.AddValue ("nCsma", "Number of \"extra\" CSMA nodes/devices", nCsma); + cmd.AddValue ("verbose", "Tell echo applications to log if true", verbose); cmd.Parse (argc,argv); if (verbose) { - LogComponentEnable(``UdpEchoClientApplication'', LOG_LEVEL_INFO); - LogComponentEnable(``UdpEchoServerApplication'', LOG_LEVEL_INFO); + LogComponentEnable("UdpEchoClientApplication", LOG_LEVEL_INFO); + LogComponentEnable("UdpEchoServerApplication", LOG_LEVEL_INFO); } nCsma = nCsma == 0 ? 1 : nCsma; -@end verbatim The next step is to create two nodes that we will connect via the -point-to-point link. The @code{NodeContainer} is used to do this just as was -done in @code{first.cc}. +point-to-point link. The ``NodeContainer`` is used to do this just as was +done in ``first.cc``. + +:: -@verbatim NodeContainer p2pNodes; p2pNodes.Create (2); -@end verbatim -Next, we declare another @code{NodeContainer} to hold the nodes that will be +Next, we declare another ``NodeContainer`` to hold the nodes that will be part of the bus (CSMA) network. First, we just instantiate the container object itself. -@verbatim +:: + NodeContainer csmaNodes; csmaNodes.Add (p2pNodes.Get (1)); csmaNodes.Create (nCsma); -@end verbatim -The next line of code @code{Gets} the first node (as in having an index of one) +The next line of code ``Gets`` the first node (as in having an index of one) from the point-to-point node container and adds it to the container of nodes that will get CSMA devices. The node in question is going to end up with a -point-to-point device @emph{and} a CSMA device. We then create a number of -``extra'' nodes that compose the remainder of the CSMA network. Since we +point-to-point device *and* a CSMA device. We then create a number of +"extra" nodes that compose the remainder of the CSMA network. Since we already have one node in the CSMA network -- the one that will have both a -point-to-point and CSMA net device, the number of ``extra'' nodes means the +point-to-point and CSMA net device, the number of "extra" nodes means the number nodes you desire in the CSMA section minus one. The next bit of code should be quite familiar by now. We instantiate a -@code{PointToPointHelper} and set the associated default @code{Attributes} so +``PointToPointHelper`` and set the associated default ``Attributes`` so that we create a five megabit per second transmitter on devices created using the helper and a two millisecond delay on channels created by the helper. -@verbatim +:: + PointToPointHelper pointToPoint; pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("5Mbps")); pointToPoint.SetChannelAttribute ("Delay", StringValue ("2ms")); NetDeviceContainer p2pDevices; p2pDevices = pointToPoint.Install (p2pNodes); -@end verbatim -We then instantiate a @code{NetDeviceContainer} to keep track of the -point-to-point net devices and we @code{Install} devices on the +We then instantiate a ``NetDeviceContainer`` to keep track of the +point-to-point net devices and we ``Install`` devices on the point-to-point nodes. We mentioned above that you were going to see a helper for CSMA devices and -channels, and the next lines introduce them. The @code{CsmaHelper} works just -like a @code{PointToPointHelper}, but it creates and connects CSMA devices and +channels, and the next lines introduce them. The ``CsmaHelper`` works just +like a ``PointToPointHelper``, but it creates and connects CSMA devices and channels. In the case of a CSMA device and channel pair, notice that the data -rate is specified by a @emph{channel} @code{Attribute} instead of a device -@code{Attribute}. This is because a real CSMA network does not allow one to mix, +rate is specified by a *channel* ``Attribute`` instead of a device +``Attribute``. This is because a real CSMA network does not allow one to mix, for example, 10Base-T and 100Base-T devices on a given channel. We first set the data rate to 100 megabits per second, and then set the speed-of-light delay of the channel to 6560 nano-seconds (arbitrarily chosen as 1 nanosecond per foot -over a 100 meter segment). Notice that you can set an @code{Attribute} using +over a 100 meter segment). Notice that you can set an ``Attribute`` using its native data type. -@verbatim +:: + CsmaHelper csma; csma.SetChannelAttribute ("DataRate", StringValue ("100Mbps")); csma.SetChannelAttribute ("Delay", TimeValue (NanoSeconds (6560))); NetDeviceContainer csmaDevices; csmaDevices = csma.Install (csmaNodes); -@end verbatim -Just as we created a @code{NetDeviceContainer} to hold the devices created by -the @code{PointToPointHelper} we create a @code{NetDeviceContainer} to hold -the devices created by our @code{CsmaHelper}. We call the @code{Install} -method of the @code{CsmaHelper} to install the devices into the nodes of the -@code{csmaNodes NodeContainer}. +Just as we created a ``NetDeviceContainer`` to hold the devices created by +the ``PointToPointHelper`` we create a ``NetDeviceContainer`` to hold +the devices created by our ``CsmaHelper``. We call the ``Install`` +method of the ``CsmaHelper`` to install the devices into the nodes of the +``csmaNodes NodeContainer``. We now have our nodes, devices and channels created, but we have no protocol -stacks present. Just as in the @code{first.cc} script, we will use the -@code{InternetStackHelper} to install these stacks. +stacks present. Just as in the ``first.cc`` script, we will use the +``InternetStackHelper`` to install these stacks. + +:: -@verbatim InternetStackHelper stack; stack.Install (p2pNodes.Get (0)); stack.Install (csmaNodes); -@end verbatim -Recall that we took one of the nodes from the @code{p2pNodes} container and -added it to the @code{csmaNodes} container. Thus we only need to install -the stacks on the remaining @code{p2pNodes} node, and all of the nodes in the -@code{csmaNodes} container to cover all of the nodes in the simulation. +Recall that we took one of the nodes from the ``p2pNodes`` container and +added it to the ``csmaNodes`` container. Thus we only need to install +the stacks on the remaining ``p2pNodes`` node, and all of the nodes in the +``csmaNodes`` container to cover all of the nodes in the simulation. -Just as in the @code{first.cc} example script, we are going to use the -@code{Ipv4AddressHelper} to assign IP addresses to our device interfaces. +Just as in the ``first.cc`` example script, we are going to use the +``Ipv4AddressHelper`` to assign IP addresses to our device interfaces. First we use the network 10.1.1.0 to create the two addresses needed for our two point-to-point devices. -@verbatim +:: + Ipv4AddressHelper address; address.SetBase ("10.1.1.0", "255.255.255.0"); Ipv4InterfaceContainer p2pInterfaces; p2pInterfaces = address.Assign (p2pDevices); -@end verbatim Recall that we save the created interfaces in a container to make it easy to pull out addressing information later for use in setting up the applications. @@ -238,50 +217,51 @@ CSMA devices --- remember we made the number of CSMA devices changeable by command line argument. The CSMA devices will be associated with IP addresses from network number 10.1.2.0 in this case, as seen below. -@verbatim +:: + address.SetBase ("10.1.2.0", "255.255.255.0"); Ipv4InterfaceContainer csmaInterfaces; csmaInterfaces = address.Assign (csmaDevices); -@end verbatim Now we have a topology built, but we need applications. This section is going to be fundamentally similar to the applications section of -@code{first.cc} but we are going to instantiate the server on one of the +``first.cc`` but we are going to instantiate the server on one of the nodes that has a CSMA device and the client on the node having only a point-to-point device. -First, we set up the echo server. We create a @code{UdpEchoServerHelper} and -provide a required @code{Attribute} value to the constructor which is the server +First, we set up the echo server. We create a ``UdpEchoServerHelper`` and +provide a required ``Attribute`` value to the constructor which is the server port number. Recall that this port can be changed later using the -@code{SetAttribute} method if desired, but we require it to be provided to +``SetAttribute`` method if desired, but we require it to be provided to the constructor. -@verbatim +:: + UdpEchoServerHelper echoServer (9); ApplicationContainer serverApps = echoServer.Install (csmaNodes.Get (nCsma)); serverApps.Start (Seconds (1.0)); serverApps.Stop (Seconds (10.0)); -@end verbatim -Recall that the @code{csmaNodes NodeContainer} contains one of the -nodes created for the point-to-point network and @code{nCsma} ``extra'' nodes. -What we want to get at is the last of the ``extra'' nodes. The zeroth entry of -the @code{csmaNodes} container will be the point-to-point node. The easy -way to think of this, then, is if we create one ``extra'' CSMA node, then it -will be at index one of the @code{csmaNodes} container. By induction, -if we create @code{nCsma} ``extra'' nodes the last one will be at index -@code{nCsma}. You see this exhibited in the @code{Get} of the first line of +Recall that the ``csmaNodes NodeContainer`` contains one of the +nodes created for the point-to-point network and ``nCsma`` "extra" nodes. +What we want to get at is the last of the "extra" nodes. The zeroth entry of +the ``csmaNodes`` container will be the point-to-point node. The easy +way to think of this, then, is if we create one "extra" CSMA node, then it +will be at index one of the ``csmaNodes`` container. By induction, +if we create ``nCsma`` "extra" nodes the last one will be at index +``nCsma``. You see this exhibited in the ``Get`` of the first line of code. -The client application is set up exactly as we did in the @code{first.cc} -example script. Again, we provide required @code{Attributes} to the -@code{UdpEchoClientHelper} in the constructor (in this case the remote address +The client application is set up exactly as we did in the ``first.cc`` +example script. Again, we provide required ``Attributes`` to the +``UdpEchoClientHelper`` in the constructor (in this case the remote address and port). We tell the client to send packets to the server we just installed -on the last of the ``extra'' CSMA nodes. We install the client on the +on the last of the "extra" CSMA nodes. We install the client on the leftmost point-to-point node seen in the topology illustration. -@verbatim +:: + UdpEchoClientHelper echoClient (csmaInterfaces.GetAddress (nCsma), 9); echoClient.SetAttribute ("MaxPackets", UintegerValue (1)); echoClient.SetAttribute ("Interval", TimeValue (Seconds (1.))); @@ -290,10 +270,9 @@ leftmost point-to-point node seen in the topology illustration. ApplicationContainer clientApps = echoClient.Install (p2pNodes.Get (0)); clientApps.Start (Seconds (2.0)); clientApps.Stop (Seconds (10.0)); -@end verbatim Since we have actually built an internetwork here, we need some form of -internetwork routing. @command{ns-3} provides what we call global routing to +internetwork routing. |ns3| provides what we call global routing to help you out. Global routing takes advantage of the fact that the entire internetwork is accessible in the simulation and runs through the all of the nodes created for the simulation --- it does the hard work of setting up routing @@ -306,19 +285,19 @@ directly to a global route manager which uses this global information to construct the routing tables for each node. Setting up this form of routing is a one-liner: -@verbatim +:: + Ipv4GlobalRoutingHelper::PopulateRoutingTables (); -@end verbatim Next we enable pcap tracing. The first line of code to enable pcap tracing in the point-to-point helper should be familiar to you by now. The second line enables pcap tracing in the CSMA helper and there is an extra parameter you haven't encountered yet. -@verbatim +:: + pointToPoint.EnablePcapAll ("second"); csma.EnablePcap ("second", csmaDevices.Get (1), true); -@end verbatim The CSMA network is a multi-point-to-point network. This means that there can (and are in this case) multiple endpoints on a shared medium. Each of @@ -327,111 +306,111 @@ alternatives to gathering trace information from such a network. One way is to create a trace file for each net device and store only the packets that are emitted or consumed by that net device. Another way is to pick one of the devices and place it in promiscuous mode. That single device -then ``sniffs'' the network for all packets and stores them in a single -pcap file. This is how @code{tcpdump}, for example, works. That final +then "sniffs" the network for all packets and stores them in a single +pcap file. This is how ``tcpdump``, for example, works. That final parameter tells the CSMA helper whether or not to arrange to capture packets in promiscuous mode. In this example, we are going to select one of the devices on the CSMA network and ask it to perform a promiscuous sniff of the network, thereby -emulating what @code{tcpdump} would do. If you were on a Linux machine -you might do something like @code{tcpdump -i eth0} to get the trace. -In this case, we specify the device using @code{csmaDevices.Get(1)}, +emulating what ``tcpdump`` would do. If you were on a Linux machine +you might do something like ``tcpdump -i eth0`` to get the trace. +In this case, we specify the device using ``csmaDevices.Get(1)``, which selects the first device in the container. Setting the final parameter to true enables promiscuous captures. The last section of code just runs and cleans up the simulation just like -the @code{first.cc} example. +the ``first.cc`` example. + +:: -@verbatim Simulator::Run (); Simulator::Destroy (); return 0; } -@end verbatim -In order to run this example, copy the @code{second.cc} example script into +In order to run this example, copy the ``second.cc`` example script into the scratch directory and use waf to build just as you did with -the @code{first.cc} example. If you are in the top-level directory of the +the ``first.cc`` example. If you are in the top-level directory of the repository you just type, -@verbatim +:: + cp examples/tutorial/second.cc scratch/mysecond.cc ./waf -@end verbatim -Warning: We use the file @code{second.cc} as one of our regression tests to +Warning: We use the file ``second.cc`` as one of our regression tests to verify that it works exactly as we think it should in order to make your tutorial experience a positive one. This means that an executable named -@code{second} already exists in the project. To avoid any confusion -about what you are executing, please do the renaming to @code{mysecond.cc} +``second`` already exists in the project. To avoid any confusion +about what you are executing, please do the renaming to ``mysecond.cc`` suggested above. If you are following the tutorial religiously (you are, aren't you) you will still have the NS_LOG variable set, so go ahead and clear that variable and run the program. -@verbatim +:: + export NS_LOG= ./waf --run scratch/mysecond -@end verbatim Since we have set up the UDP echo applications to log just as we did in -@code{first.cc}, you will see similar output when you run the script. +``first.cc``, you will see similar output when you run the script. + +:: -@verbatim Waf: Entering directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' 'build' finished successfully (0.415s) Sent 1024 bytes to 10.1.2.4 Received 1024 bytes from 10.1.1.1 Received 1024 bytes from 10.1.2.4 -@end verbatim -Recall that the first message, ``@code{Sent 1024 bytes to 10.1.2.4},'' is the +Recall that the first message, "``Sent 1024 bytes to 10.1.2.4``," is the UDP echo client sending a packet to the server. In this case, the server -is on a different network (10.1.2.0). The second message, ``@code{Received 1024 -bytes from 10.1.1.1},'' is from the UDP echo server, generated when it receives -the echo packet. The final message, ``@code{Received 1024 bytes from 10.1.2.4},'' +is on a different network (10.1.2.0). The second message, "``Received 1024 +bytes from 10.1.1.1``," is from the UDP echo server, generated when it receives +the echo packet. The final message, "``Received 1024 bytes from 10.1.2.4``," is from the echo client, indicating that it has received its echo back from the server. If you now go and look in the top level directory, you will find three trace files: -@verbatim +:: + second-0-0.pcap second-1-0.pcap second-2-0.pcap -@end verbatim Let's take a moment to look at the naming of these files. They all have the -same form, @code{--.pcap}. For example, the first file -in the listing is @code{second-0-0.pcap} which is the pcap trace from node +same form, ``--.pcap``. For example, the first file +in the listing is ``second-0-0.pcap`` which is the pcap trace from node zero, device zero. This is the point-to-point net device on node zero. The -file @code{second-1-0.pcap} is the pcap trace for device zero on node one, -also a point-to-point net device; and the file @code{second-2-0.pcap} is the +file ``second-1-0.pcap`` is the pcap trace for device zero on node one, +also a point-to-point net device; and the file ``second-2-0.pcap`` is the pcap trace for device zero on node two. If you refer back to the topology illustration at the start of the section, you will see that node zero is the leftmost node of the point-to-point link and node one is the node that has both a point-to-point device and a CSMA -device. You will see that node two is the first ``extra'' node on the CSMA +device. You will see that node two is the first "extra" node on the CSMA network and its device zero was selected as the device to capture the promiscuous-mode trace. Now, let's follow the echo packet through the internetwork. First, do a tcpdump of the trace file for the leftmost point-to-point node --- node zero. -@verbatim +:: + tcpdump -nn -tt -r second-0-0.pcap -@end verbatim You should see the contents of the pcap file displayed: -@verbatim +:: + reading from file second-0-0.pcap, link-type PPP (PPP) 2.000000 IP 10.1.1.1.49153 > 10.1.2.4.9: UDP, length 1024 2.007602 IP 10.1.2.4.9 > 10.1.1.1.49153: UDP, length 1024 -@end verbatim The first line of the dump indicates that the link type is PPP (point-to-point) which we expect. You then see the echo packet leaving node zero via the @@ -440,18 +419,18 @@ device associated with IP address 10.1.1.1 headed for IP address point-to-point link and be received by the point-to-point net device on node one. Let's take a look: -@verbatim +:: + tcpdump -nn -tt -r second-1-0.pcap -@end verbatim You should now see the pcap trace output of the other side of the point-to-point link: -@verbatim -reading from file second-1-0.pcap, link-type PPP (PPP) -2.003686 IP 10.1.1.1.49153 > 10.1.2.4.9: UDP, length 1024 -2.003915 IP 10.1.2.4.9 > 10.1.1.1.49153: UDP, length 1024 -@end verbatim +:: + + reading from file second-1-0.pcap, link-type PPP (PPP) + 2.003686 IP 10.1.1.1.49153 > 10.1.2.4.9: UDP, length 1024 + 2.003915 IP 10.1.2.4.9 > 10.1.1.1.49153: UDP, length 1024 Here we see that the link type is also PPP as we would expect. You see the packet from IP address 10.1.1.1 (that was sent at 2.000000 seconds) headed @@ -462,13 +441,14 @@ pop out on that device headed for its ultimate destination. Remember that we selected node 2 as the promiscuous sniffer node for the CSMA network so let's then look at second-2-0.pcap and see if its there. -@verbatim +:: + tcpdump -nn -tt -r second-2-0.pcap -@end verbatim You should now see the promiscuous dump of node two, device zero: -@verbatim +:: + reading from file second-2-0.pcap, link-type EN10MB (Ethernet) 2.003696 arp who-has 10.1.2.4 (ff:ff:ff:ff:ff:ff) tell 10.1.2.1 2.003707 arp reply 10.1.2.4 is-at 00:00:00:00:00:06 @@ -476,10 +456,9 @@ You should now see the promiscuous dump of node two, device zero: 2.003811 arp who-has 10.1.2.1 (ff:ff:ff:ff:ff:ff) tell 10.1.2.4 2.003822 arp reply 10.1.2.1 is-at 00:00:00:00:00:03 2.003915 IP 10.1.2.4.9 > 10.1.1.1.49153: UDP, length 1024 -@end verbatim -As you can see, the link type is now ``Ethernet''. Something new has appeared, -though. The bus network needs @code{ARP}, the Address Resolution Protocol. +As you can see, the link type is now "Ethernet". Something new has appeared, +though. The bus network needs ``ARP``, the Address Resolution Protocol. Node one knows it needs to send the packet to IP address 10.1.2.4, but it doesn't know the MAC address of the corresponding node. It broadcasts on the CSMA network (ff:ff:ff:ff:ff:ff) asking for the device that has IP address @@ -489,17 +468,17 @@ exchange, but is sniffing the network and reporting all of the traffic it sees. This exchange is seen in the following lines, -@verbatim +:: + 2.003696 arp who-has 10.1.2.4 (ff:ff:ff:ff:ff:ff) tell 10.1.2.1 2.003707 arp reply 10.1.2.4 is-at 00:00:00:00:00:06 -@end verbatim Then node one, device one goes ahead and sends the echo packet to the UDP echo server at IP address 10.1.2.4. -@verbatim +:: + 2.003801 IP 10.1.1.1.49153 > 10.1.2.4.9: UDP, length 1024 -@end verbatim The server receives the echo request and turns the packet around trying to send it back to the source. The server knows that this address is on another network @@ -508,65 +487,65 @@ routing and it has figured all of this out for us. But, the echo server node doesn't know the MAC address of the first CSMA node, so it has to ARP for it just like the first CSMA node had to do. -@verbatim +:: + 2.003811 arp who-has 10.1.2.1 (ff:ff:ff:ff:ff:ff) tell 10.1.2.4 2.003822 arp reply 10.1.2.1 is-at 00:00:00:00:00:03 -@end verbatim The server then sends the echo back to the forwarding node. -@verbatim +:: + 2.003915 IP 10.1.2.4.9 > 10.1.1.1.49153: UDP, length 1024 -@end verbatim Looking back at the rightmost node of the point-to-point link, -@verbatim +:: + tcpdump -nn -tt -r second-1-0.pcap -@end verbatim You can now see the echoed packet coming back onto the point-to-point link as the last line of the trace dump. -@verbatim -reading from file second-1-0.pcap, link-type PPP (PPP) -2.003686 IP 10.1.1.1.49153 > 10.1.2.4.9: UDP, length 1024 -2.003915 IP 10.1.2.4.9 > 10.1.1.1.49153: UDP, length 1024 -@end verbatim +:: + + reading from file second-1-0.pcap, link-type PPP (PPP) + 2.003686 IP 10.1.1.1.49153 > 10.1.2.4.9: UDP, length 1024 + 2.003915 IP 10.1.2.4.9 > 10.1.1.1.49153: UDP, length 1024 Lastly, you can look back at the node that originated the echo -@verbatim +:: + tcpdump -nn -tt -r second-0-0.pcap -@end verbatim and see that the echoed packet arrives back at the source at 2.007602 seconds, -@verbatim +:: + reading from file second-0-0.pcap, link-type PPP (PPP) 2.000000 IP 10.1.1.1.49153 > 10.1.2.4.9: UDP, length 1024 2.007602 IP 10.1.2.4.9 > 10.1.1.1.49153: UDP, length 1024 -@end verbatim Finally, recall that we added the ability to control the number of CSMA devices in the simulation by command line argument. You can change this argument in the same way as when we looked at changing the number of packets echoed in the -@code{first.cc} example. Try running the program with the number of ``extra'' +``first.cc`` example. Try running the program with the number of "extra" devices set to four: -@verbatim +:: + ./waf --run "scratch/mysecond --nCsma=4" -@end verbatim You should now see, -@verbatim +:: + Waf: Entering directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' 'build' finished successfully (0.405s) Sent 1024 bytes to 10.1.2.5 Received 1024 bytes from 10.1.1.1 Received 1024 bytes from 10.1.2.5 -@end verbatim Notice that the echo server has now been relocated to the last of the CSMA nodes, which is 10.1.2.5 instead of the default case, 10.1.2.4. @@ -576,16 +555,16 @@ a bystander in the CSMA network. You may really want to get a trace from a single device and you may not be interested in any other traffic on the network. You can do this fairly easily. -Let's take a look at @code{scratch/mysecond.cc} and add that code enabling us -to be more specific. @code{ns-3} helpers provide methods that take a node +Let's take a look at ``scratch/mysecond.cc`` and add that code enabling us +to be more specific. ``ns-3`` helpers provide methods that take a node number and device number as parameters. Go ahead and replace the -@code{EnablePcap} calls with the calls below. +``EnablePcap`` calls with the calls below. + +:: -@verbatim pointToPoint.EnablePcap ("second", p2pNodes.Get (0)->GetId (), 0); csma.EnablePcap ("second", csmaNodes.Get (nCsma)->GetId (), 0, false); csma.EnablePcap ("second", csmaNodes.Get (nCsma-1)->GetId (), 0, false); -@end verbatim We know that we want to create a pcap file with the base name "second" and we also know that the device of interest in both cases is going to be zero, @@ -594,64 +573,64 @@ so those parameters are not really interesting. In order to get the node number, you have two choices: first, nodes are numbered in a monotonically increasing fashion starting from zero in the order in which you created them. One way to get a node number is to figure -this number out ``manually'' by contemplating the order of node creation. +this number out "manually" by contemplating the order of node creation. If you take a look at the network topology illustration at the beginning of the file, we did this for you and you can see that the last CSMA node is -going to be node number @code{nCsma + 1}. This approach can become +going to be node number ``nCsma + 1``. This approach can become annoyingly difficult in larger simulations. An alternate way, which we use here, is to realize that the -@code{NodeContainers} contain pointers to @command{ns-3} @code{Node} Objects. -The @code{Node} Object has a method called @code{GetId} which will return that +``NodeContainers`` contain pointers to |ns3| ``Node`` Objects. +The ``Node`` Object has a method called ``GetId`` which will return that node's ID, which is the node number we seek. Let's go take a look at the -Doxygen for the @code{Node} and locate that method, which is further down in -the @command{ns-3} core code than we've seen so far; but sometimes you have to +Doxygen for the ``Node`` and locate that method, which is further down in +the |ns3| core code than we've seen so far; but sometimes you have to search diligently for useful things. Go to the Doxygen documentation for your release (recall that you can find it -on the project web site). You can get to the @code{Node} documentation by -looking through at the ``Classes'' tab and scrolling down the ``Class List'' -until you find @code{ns3::Node}. Select @code{ns3::Node} and you will be taken -to the documentation for the @code{Node} class. If you now scroll down to the -@code{GetId} method and select it, you will be taken to the detailed -documentation for the method. Using the @code{GetId} method can make +on the project web site). You can get to the ``Node`` documentation by +looking through at the "Classes" tab and scrolling down the "Class List" +until you find ``ns3::Node``. Select ``ns3::Node`` and you will be taken +to the documentation for the ``Node`` class. If you now scroll down to the +``GetId`` method and select it, you will be taken to the detailed +documentation for the method. Using the ``GetId`` method can make determining node numbers much easier in complex topologies. Let's clear the old trace files out of the top-level directory to avoid confusion about what is going on, -@verbatim +:: + rm *.pcap rm *.tr -@end verbatim -If you build the new script and run the simulation setting @code{nCsma} to 100, +If you build the new script and run the simulation setting ``nCsma`` to 100, + +:: -@verbatim ./waf --run "scratch/mysecond --nCsma=100" -@end verbatim you will see the following output: -@verbatim +:: + Waf: Entering directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' 'build' finished successfully (0.407s) Sent 1024 bytes to 10.1.2.101 Received 1024 bytes from 10.1.1.1 Received 1024 bytes from 10.1.2.101 -@end verbatim Note that the echo server is now located at 10.1.2.101 which corresponds to -having 100 ``extra'' CSMA nodes with the echo server on the last one. If you +having 100 "extra" CSMA nodes with the echo server on the last one. If you list the pcap files in the top level directory you will see, -@verbatim - second-0-0.pcap second-100-0.pcap second-101-0.pcap -@end verbatim +:: -The trace file @code{second-0-0.pcap} is the ``leftmost'' point-to-point device -which is the echo packet source. The file @code{second-101-0.pcap} corresponds + second-0-0.pcap second-100-0.pcap second-101-0.pcap + +The trace file ``second-0-0.pcap`` is the "leftmost" point-to-point device +which is the echo packet source. The file ``second-101-0.pcap`` corresponds to the rightmost CSMA device which is where the echo server resides. You may have noticed that the final parameter on the call to enable pcap tracing on the echo server node was false. This means that the trace gathered on that node @@ -659,31 +638,32 @@ was in non-promiscuous mode. To illustrate the difference between promiscuous and non-promiscuous traces, we also requested a non-promiscuous trace for the next-to-last node. Go ahead and -take a look at the @code{tcpdump} for @code{second-100-0.pcap}. +take a look at the ``tcpdump`` for ``second-100-0.pcap``. + +:: -@verbatim tcpdump -nn -tt -r second-100-0.pcap -@end verbatim You can now see that node 100 is really a bystander in the echo exchange. The only packets that it receives are the ARP requests which are broadcast to the entire CSMA network. -@verbatim +:: + reading from file second-100-0.pcap, link-type EN10MB (Ethernet) 2.003696 arp who-has 10.1.2.101 (ff:ff:ff:ff:ff:ff) tell 10.1.2.1 2.003811 arp who-has 10.1.2.1 (ff:ff:ff:ff:ff:ff) tell 10.1.2.101 -@end verbatim -Now take a look at the @code{tcpdump} for @code{second-101-0.pcap}. +Now take a look at the ``tcpdump`` for ``second-101-0.pcap``. + +:: -@verbatim tcpdump -nn -tt -r second-101-0.pcap -@end verbatim You can now see that node 101 is really the participant in the echo exchange. -@verbatim +:: + reading from file second-101-0.pcap, link-type EN10MB (Ethernet) 2.003696 arp who-has 10.1.2.101 (ff:ff:ff:ff:ff:ff) tell 10.1.2.1 2.003696 arp reply 10.1.2.101 is-at 00:00:00:00:00:67 @@ -691,13 +671,9 @@ You can now see that node 101 is really the participant in the echo exchange. 2.003801 arp who-has 10.1.2.1 (ff:ff:ff:ff:ff:ff) tell 10.1.2.101 2.003822 arp reply 10.1.2.1 is-at 00:00:00:00:00:03 2.003822 IP 10.1.2.101.9 > 10.1.1.1.49153: UDP, length 1024 -@end verbatim -@c ======================================================================== -@c Models, Attributes and Reality -@c ======================================================================== -@node Models, Attributes and Reality -@section Models, Attributes and Reality +Models, Attributes and Reality +****************************** This is a convenient place to make a small excursion and make an important point. It may or may not be obvious to you, but whenever one is using a @@ -709,11 +685,11 @@ happen in a real Ethernet. This is not the case. A model is, by definition, an abstraction of reality. It is ultimately the responsibility of the simulation script author to determine the so-called -``range of accuracy'' and ``domain of applicability'' of the simulation as +"range of accuracy" and "domain of applicability" of the simulation as a whole, and therefore its constituent parts. -In some cases, like @code{Csma}, it can be fairly easy to determine what is -@emph{not} modeled. By reading the model description (@code{csma.h}) you +In some cases, like ``Csma``, it can be fairly easy to determine what is +*not* modeled. By reading the model description (``csma.h``) you can find that there is no collision detection in the CSMA model and decide on how applicable its use will be in your simulation or what caveats you may want to include with your results. In other cases, it can be quite easy @@ -722,31 +698,31 @@ and buy. It will prove worthwhile to spend some time investigating a few such instances, and how easily you can swerve outside the bounds of reality in your simulations. -As you have seen, @command{ns-3} provides @code{Attributes} which a user -can easily set to change model behavior. Consider two of the @code{Attributes} -of the @code{CsmaNetDevice}: @code{Mtu} and @code{EncapsulationMode}. -The @code{Mtu} attribute indicates the Maximum Transmission Unit to the +As you have seen, |ns3| provides ``Attributes`` which a user +can easily set to change model behavior. Consider two of the ``Attributes`` +of the ``CsmaNetDevice``: ``Mtu`` and ``EncapsulationMode``. +The ``Mtu`` attribute indicates the Maximum Transmission Unit to the device. This is the size of the largest Protocol Data Unit (PDU) that the device can send. -The MTU defaults to 1500 bytes in the @code{CsmaNetDevice}. This default -corresponds to a number found in RFC 894, ``A Standard for the Transmission -of IP Datagrams over Ethernet Networks.'' The number is actually derived +The MTU defaults to 1500 bytes in the ``CsmaNetDevice``. This default +corresponds to a number found in RFC 894, "A Standard for the Transmission +of IP Datagrams over Ethernet Networks." The number is actually derived from the maximum packet size for 10Base5 (full-spec Ethernet) networks -- 1518 bytes. If you subtract the DIX encapsulation overhead for Ethernet packets (18 bytes) you will end up with a maximum possible data size (MTU) -of 1500 bytes. One can also find that the @code{MTU} for IEEE 802.3 networks +of 1500 bytes. One can also find that the ``MTU`` for IEEE 802.3 networks is 1492 bytes. This is because LLC/SNAP encapsulation adds an extra eight bytes of overhead to the packet. In both cases, the underlying hardware can only send 1518 bytes, but the data size is different. -In order to set the encapsulation mode, the @code{CsmaNetDevice} provides -an @code{Attribute} called @code{EncapsulationMode} which can take on the -values @code{Dix} or @code{Llc}. These correspond to Ethernet and LLC/SNAP +In order to set the encapsulation mode, the ``CsmaNetDevice`` provides +an ``Attribute`` called ``EncapsulationMode`` which can take on the +values ``Dix`` or ``Llc``. These correspond to Ethernet and LLC/SNAP framing respectively. -If one leaves the @code{Mtu} at 1500 bytes and changes the encapsulation mode -to @code{Llc}, the result will be a network that encapsulates 1500 byte PDUs +If one leaves the ``Mtu`` at 1500 bytes and changes the encapsulation mode +to ``Llc``, the result will be a network that encapsulates 1500 byte PDUs with LLC/SNAP framing resulting in packets of 1526 bytes, which would be illegal in many networks, since they can transmit a maximum of 1518 bytes per packet. This would most likely result in a simulation that quite subtly does @@ -755,16 +731,16 @@ not reflect the reality you might be expecting. Just to complicate the picture, there exist jumbo frames (1500 < MTU <= 9000 bytes) and super-jumbo (MTU > 9000 bytes) frames that are not officially sanctioned by IEEE but are available in some high-speed (Gigabit) networks and NICs. One -could leave the encapsulation mode set to @code{Dix}, and set the @code{Mtu} -@code{Attribute} on a @code{CsmaNetDevice} to 64000 bytes -- even though an -associated @code{CsmaChannel DataRate} was set at 10 megabits per second. +could leave the encapsulation mode set to ``Dix``, and set the ``Mtu`` +``Attribute`` on a ``CsmaNetDevice`` to 64000 bytes -- even though an +associated ``CsmaChannel DataRate`` was set at 10 megabits per second. This would essentially model an Ethernet switch made out of vampire-tapped 1980s-style 10Base5 networks that support super-jumbo datagrams. This is certainly not something that was ever made, nor is likely to ever be made, but it is quite easy for you to configure. In the previous example, you used the command line to create a simulation that -had 100 @code{Csma} nodes. You could have just as easily created a simulation +had 100 ``Csma`` nodes. You could have just as easily created a simulation with 500 nodes. If you were actually modeling that 10Base5 vampire-tap network, the maximum length of a full-spec Ethernet cable is 500 meters, with a minimum tap spacing of 2.5 meters. That means there could only be 200 taps on a @@ -772,47 +748,42 @@ real network. You could have quite easily built an illegal network in that way as well. This may or may not result in a meaningful simulation depending on what you are trying to model. -Similar situations can occur in many places in @command{ns-3} and in any +Similar situations can occur in many places in |ns3| and in any simulator. For example, you may be able to position nodes in such a way that they occupy the same space at the same time, or you may be able to configure amplifiers or noise levels that violate the basic laws of physics. -@command{ns-3} generally favors flexibility, and many models will allow freely -setting @code{Attributes} without trying to enforce any arbitrary consistency +|ns3| generally favors flexibility, and many models will allow freely +setting ``Attributes`` without trying to enforce any arbitrary consistency or particular underlying spec. -The thing to take home from this is that @command{ns-3} is going to provide a +The thing to take home from this is that |ns3| is going to provide a super-flexible base for you to experiment with. It is up to you to understand what you are asking the system to do and to make sure that the simulations you create have some meaning and some connection with a reality defined by you. -@c ======================================================================== -@c Building a Wireless Network Topology -@c ======================================================================== -@node Building a Wireless Network Topology -@section Building a Wireless Network Topology +Building a Wireless Network Topology +************************************ -@cindex topology -@cindex wireless network topology -In this section we are going to further expand our knowledge of @command{ns-3} +In this section we are going to further expand our knowledge of |ns3| network devices and channels to cover an example of a wireless network. -@command{Ns-3} provides a set of 802.11 models that attempt to provide an +|ns3| provides a set of 802.11 models that attempt to provide an accurate MAC-level implementation of the 802.11 specification and a -``not-so-slow'' PHY-level model of the 802.11a specification. +"not-so-slow" PHY-level model of the 802.11a specification. Just as we have seen both point-to-point and CSMA topology helper objects when -constructing point-to-point topologies, we will see equivalent @code{Wifi} +constructing point-to-point topologies, we will see equivalent ``Wifi`` topology helpers in this section. The appearance and operation of these helpers should look quite familiar to you. -We provide an example script in our @code{examples/tutorial} directory. This script -builds on the @code{second.cc} script and adds a Wifi network. Go ahead and -open @code{examples/tutorial/third.cc} in your favorite editor. You will have already -seen enough @command{ns-3} code to understand most of what is going on in +We provide an example script in our ``examples/tutorial`` directory. This script +builds on the ``second.cc`` script and adds a Wifi network. Go ahead and +open ``examples/tutorial/third.cc`` in your favorite editor. You will have already +seen enough |ns3| code to understand most of what is going on in this example, but there are a few new things, so we will go over the entire script and examine some of the output. -Just as in the @code{second.cc} example (and in all @command{ns-3} examples) +Just as in the ``second.cc`` example (and in all |ns3| examples) the file begins with an emacs mode line and some GPL boilerplate. Take a look at the ASCII art (reproduced below) that shows the default network @@ -820,29 +791,30 @@ topology constructed in the example. You can see that we are going to further extend our example by hanging a wireless network off of the left side. Notice that this is a default network topology since you can actually vary the number of nodes created on the wired and wireless networks. Just as in the -@code{second.cc} script case, if you change @code{nCsma}, it will give you a -number of ``extra'' CSMA nodes. Similarly, you can set @code{nWifi} to -control how many @code{STA} (station) nodes are created in the simulation. -There will always be one @code{AP} (access point) node on the wireless -network. By default there are three ``extra'' CSMA nodes and three wireless -@code{STA} nodes. +``second.cc`` script case, if you change ``nCsma``, it will give you a +number of "extra" CSMA nodes. Similarly, you can set ``nWifi`` to +control how many ``STA`` (station) nodes are created in the simulation. +There will always be one ``AP`` (access point) node on the wireless +network. By default there are three "extra" CSMA nodes and three wireless +``STA`` nodes. The code begins by loading module include files just as was done in the -@code{second.cc} example. There are a couple of new includes corresponding +``second.cc`` example. There are a couple of new includes corresponding to the Wifi module and the mobility module which we will discuss below. -@verbatim +:: + #include "ns3/core-module.h" #include "ns3/simulator-module.h" #include "ns3/node-module.h" #include "ns3/helper-module.h" #include "ns3/wifi-module.h" #include "ns3/mobility-module.h" -@end verbatim The network topology illustration follows: -@verbatim +:: + // Default Network Topology // // Wifi 10.1.3.0 @@ -853,211 +825,211 @@ The network topology illustration follows: // point-to-point | | | | // ================ // LAN 10.1.2.0 -@end verbatim You can see that we are adding a new network device to the node on the left side of the point-to-point link that becomes the access point for the wireless network. A number of wireless STA nodes are created to fill out the new 10.1.3.0 network as shown on the left side of the illustration. -After the illustration, the @code{ns-3} namespace is @code{used} and a logging +After the illustration, the ``ns-3`` namespace is ``used`` and a logging component is defined. This should all be quite familiar by now. -@verbatim +:: + using namespace ns3; NS_LOG_COMPONENT_DEFINE ("ThirdScriptExample"); -@end verbatim -The main program begins just like @code{second.cc} by adding some command line +The main program begins just like ``second.cc`` by adding some command line parameters for enabling or disabling logging components and for changing the number of devices created. -@verbatim +:: + bool verbose = true; uint32_t nCsma = 3; uint32_t nWifi = 3; CommandLine cmd; - cmd.AddValue (``nCsma'', ``Number of \"extra\" CSMA nodes/devices'', nCsma); - cmd.AddValue (``nWifi'', ``Number of wifi STA devices'', nWifi); - cmd.AddValue (``verbose'', ``Tell echo applications to log if true'', verbose); + cmd.AddValue ("nCsma", "Number of \"extra\" CSMA nodes/devices", nCsma); + cmd.AddValue ("nWifi", "Number of wifi STA devices", nWifi); + cmd.AddValue ("verbose", "Tell echo applications to log if true", verbose); cmd.Parse (argc,argv); if (verbose) { - LogComponentEnable(``UdpEchoClientApplication'', LOG_LEVEL_INFO); - LogComponentEnable(``UdpEchoServerApplication'', LOG_LEVEL_INFO); + LogComponentEnable("UdpEchoClientApplication", LOG_LEVEL_INFO); + LogComponentEnable("UdpEchoServerApplication", LOG_LEVEL_INFO); } -@end verbatim Just as in all of the previous examples, the next step is to create two nodes that we will connect via the point-to-point link. -@verbatim +:: + NodeContainer p2pNodes; p2pNodes.Create (2); -@end verbatim -Next, we see an old friend. We instantiate a @code{PointToPointHelper} and -set the associated default @code{Attributes} so that we create a five megabit +Next, we see an old friend. We instantiate a ``PointToPointHelper`` and +set the associated default ``Attributes`` so that we create a five megabit per second transmitter on devices created using the helper and a two millisecond -delay on channels created by the helper. We then @code{Intall} the devices +delay on channels created by the helper. We then ``Intall`` the devices on the nodes and the channel between them. -@verbatim +:: + PointToPointHelper pointToPoint; pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("5Mbps")); pointToPoint.SetChannelAttribute ("Delay", StringValue ("2ms")); NetDeviceContainer p2pDevices; p2pDevices = pointToPoint.Install (p2pNodes); -@end verbatim -Next, we declare another @code{NodeContainer} to hold the nodes that will be +Next, we declare another ``NodeContainer`` to hold the nodes that will be part of the bus (CSMA) network. -@verbatim +:: + NodeContainer csmaNodes; csmaNodes.Add (p2pNodes.Get (1)); csmaNodes.Create (nCsma); -@end verbatim -The next line of code @code{Gets} the first node (as in having an index of one) +The next line of code ``Gets`` the first node (as in having an index of one) from the point-to-point node container and adds it to the container of nodes that will get CSMA devices. The node in question is going to end up with a -point-to-point device and a CSMA device. We then create a number of ``extra'' +point-to-point device and a CSMA device. We then create a number of "extra" nodes that compose the remainder of the CSMA network. -We then instantiate a @code{CsmaHelper} and set its @code{Attributes} as we did -in the previous example. We create a @code{NetDeviceContainer} to keep track of -the created CSMA net devices and then we @code{Install} CSMA devices on the +We then instantiate a ``CsmaHelper`` and set its ``Attributes`` as we did +in the previous example. We create a ``NetDeviceContainer`` to keep track of +the created CSMA net devices and then we ``Install`` CSMA devices on the selected nodes. -@verbatim +:: + CsmaHelper csma; csma.SetChannelAttribute ("DataRate", StringValue ("100Mbps")); csma.SetChannelAttribute ("Delay", TimeValue (NanoSeconds (6560))); NetDeviceContainer csmaDevices; csmaDevices = csma.Install (csmaNodes); -@end verbatim Next, we are going to create the nodes that will be part of the Wifi network. -We are going to create a number of ``station'' nodes as specified by the -command line argument, and we are going to use the ``leftmost'' node of the +We are going to create a number of "station" nodes as specified by the +command line argument, and we are going to use the "leftmost" node of the point-to-point link as the node for the access point. -@verbatim +:: + NodeContainer wifiStaNodes; wifiStaNodes.Create (nWifi); NodeContainer wifiApNode = p2pNodes.Get (0); -@end verbatim The next bit of code constructs the wifi devices and the interconnection channel between these wifi nodes. First, we configure the PHY and channel helpers: -@verbatim +:: + YansWifiChannelHelper channel = YansWifiChannelHelper::Default (); YansWifiPhyHelper phy = YansWifiPhyHelper::Default (); -@end verbatim For simplicity, this code uses the default PHY layer configuration and channel models which are documented in the API doxygen documentation for -the @code{YansWifiChannelHelper::Default} and @code{YansWifiPhyHelper::Default} +the ``YansWifiChannelHelper::Default`` and ``YansWifiPhyHelper::Default`` methods. Once these objects are created, we create a channel object and associate it to our PHY layer object manager to make sure -that all the PHY layer objects created by the @code{YansWifiPhyHelper} +that all the PHY layer objects created by the ``YansWifiPhyHelper`` share the same underlying channel, that is, they share the same wireless medium and can communication and interfere: -@verbatim +:: + phy.SetChannel (channel.Create ()); -@end verbatim Once the PHY helper is configured, we can focus on the MAC layer. Here we choose to work with non-Qos MACs so we use a NqosWifiMacHelper object to set MAC parameters. -@verbatim +:: + WifiHelper wifi = WifiHelper::Default (); wifi.SetRemoteStationManager ("ns3::AarfWifiManager"); NqosWifiMacHelper mac = NqosWifiMacHelper::Default (); -@end verbatim -The @code{SetRemoteStationManager} method tells the helper the type of +The ``SetRemoteStationManager`` method tells the helper the type of rate control algorithm to use. Here, it is asking the helper to use the AARF algorithm --- details are, of course, available in Doxygen. Next, we configure the type of MAC, the SSID of the infrastructure network we want to setup and make sure that our stations don't perform active probing: -@verbatim +:: + Ssid ssid = Ssid ("ns-3-ssid"); mac.SetType ("ns3::StaWifiMac", "Ssid", SsidValue (ssid), "ActiveProbing", BooleanValue (false)); -@end verbatim This code first creates an 802.11 service set identifier (SSID) object -that will be used to set the value of the ``Ssid'' @code{Attribute} of +that will be used to set the value of the "Ssid" ``Attribute`` of the MAC layer implementation. The particular kind of MAC layer that -will be created by the helper is specified by @code{Attribute} as +will be created by the helper is specified by ``Attribute`` as being of the "ns3::StaWifiMac" type. The use of -@code{NqosWifiMacHelper} will ensure that the ''QosSupported'' -@code{Attribute} for created MAC objects is set false. The combination +``NqosWifiMacHelper`` will ensure that the "QosSupported" +``Attribute`` for created MAC objects is set false. The combination of these two configurations means that the MAC instance next created will be a non-QoS non-AP station (STA) in an infrastructure BSS (i.e., -a BSS with an AP). Finally, the ``ActiveProbing'' @code{Attribute} is +a BSS with an AP). Finally, the "ActiveProbing" ``Attribute`` is set to false. This means that probe requests will not be sent by MACs created by this helper. Once all the station-specific parameters are fully configured, both at the -MAC and PHY layers, we can invoke our now-familiar @code{Install} method to +MAC and PHY layers, we can invoke our now-familiar ``Install`` method to create the wifi devices of these stations: -@verbatim +:: + NetDeviceContainer staDevices; staDevices = wifi.Install (phy, mac, wifiStaNodes); -@end verbatim We have configured Wifi for all of our STA nodes, and now we need to configure the AP (access point) node. We begin this process by changing -the default @code{Attributes} of the @code{NqosWifiMacHelper} to reflect the +the default ``Attributes`` of the ``NqosWifiMacHelper`` to reflect the requirements of the AP. -@verbatim +:: + mac.SetType ("ns3::ApWifiMac", "Ssid", SsidValue (ssid), "BeaconGeneration", BooleanValue (true), "BeaconInterval", TimeValue (Seconds (2.5))); -@end verbatim -In this case, the @code{NqosWifiMacHelper} is going to create MAC -layers of the ``ns3::ApWifiMac'', the latter specifying that a MAC +In this case, the ``NqosWifiMacHelper`` is going to create MAC +layers of the "ns3::ApWifiMac", the latter specifying that a MAC instance configured as an AP should be created, with the helper type -implying that the ''QosSupported'' @code{Attribute} should be set to +implying that the "QosSupported" ``Attribute`` should be set to false - disabling 802.11e/WMM-style QoS support at created APs. We -set the ``BeaconGeneration'' @code{Attribute} to true and also set an +set the "BeaconGeneration" ``Attribute`` to true and also set an interval between beacons of 2.5 seconds. The next lines create the single AP which shares the same set of PHY-level -@code{Attributes} (and channel) as the stations: +``Attributes`` (and channel) as the stations: + +:: -@verbatim NetDeviceContainer apDevices; apDevices = wifi.Install (phy, mac, wifiApNode); -@end verbatim Now, we are going to add mobility models. We want the STA nodes to be mobile, wandering around inside a bounding box, and we want to make the AP node -stationary. We use the @code{MobilityHelper} to make this easy for us. -First, we instantiate a @code{MobilityHelper} object and set some -@code{Attributes} controlling the ``position allocator'' functionality. +stationary. We use the ``MobilityHelper`` to make this easy for us. +First, we instantiate a ``MobilityHelper`` object and set some +``Attributes`` controlling the "position allocator" functionality. + +:: -@verbatim MobilityHelper mobility; mobility.SetPositionAllocator ("ns3::GridPositionAllocator", @@ -1067,58 +1039,58 @@ First, we instantiate a @code{MobilityHelper} object and set some "DeltaY", DoubleValue (10.0), "GridWidth", UintegerValue (3), "LayoutType", StringValue ("RowFirst")); -@end verbatim This code tells the mobility helper to use a two-dimensional grid to initially place the STA nodes. Feel free to explore the Doxygen for class -@code{ns3::GridPositionAllocator} to see exactly what is being done. +``ns3::GridPositionAllocator`` to see exactly what is being done. We have arranged our nodes on an initial grid, but now we need to tell them -how to move. We choose the @code{RandomWalk2dMobilityModel} which has the +how to move. We choose the ``RandomWalk2dMobilityModel`` which has the nodes move in a random direction at a random speed around inside a bounding box. -@verbatim +:: + mobility.SetMobilityModel ("ns3::RandomWalk2dMobilityModel", "Bounds", RectangleValue (Rectangle (-50, 50, -50, 50))); -@end verbatim -We now tell the @code{MobilityHelper} to install the mobility models on the +We now tell the ``MobilityHelper`` to install the mobility models on the STA nodes. -@verbatim +:: + mobility.Install (wifiStaNodes); -@end verbatim We want the access point to remain in a fixed position during the simulation. We accomplish this by setting the mobility model for this node to be the -@code{ns3::ConstantPositionMobilityModel}: +``ns3::ConstantPositionMobilityModel``: + +:: -@verbatim mobility.SetMobilityModel ("ns3::ConstantPositionMobilityModel"); mobility.Install (wifiApNode); -@end verbatim We now have our nodes, devices and channels created, and mobility models chosen for the Wifi nodes, but we have no protocol stacks present. Just as -we have done previously many times, we will use the @code{InternetStackHelper} +we have done previously many times, we will use the ``InternetStackHelper`` to install these stacks. -@verbatim +:: + InternetStackHelper stack; stack.Install (csmaNodes); stack.Install (wifiApNode); stack.Install (wifiStaNodes); -@end verbatim -Just as in the @code{second.cc} example script, we are going to use the -@code{Ipv4AddressHelper} to assign IP addresses to our device interfaces. +Just as in the ``second.cc`` example script, we are going to use the +``Ipv4AddressHelper`` to assign IP addresses to our device interfaces. First we use the network 10.1.1.0 to create the two addresses needed for our two point-to-point devices. Then we use network 10.1.2.0 to assign addresses to the CSMA network and then we assign addresses from network 10.1.3.0 to both the STA devices and the AP on the wireless network. -@verbatim +:: + Ipv4AddressHelper address; address.SetBase ("10.1.1.0", "255.255.255.0"); @@ -1132,23 +1104,23 @@ both the STA devices and the AP on the wireless network. address.SetBase ("10.1.3.0", "255.255.255.0"); address.Assign (staDevices); address.Assign (apDevices); -@end verbatim -We put the echo server on the ``rightmost'' node in the illustration at the +We put the echo server on the "rightmost" node in the illustration at the start of the file. We have done this before. -@verbatim +:: + UdpEchoServerHelper echoServer (9); ApplicationContainer serverApps = echoServer.Install (csmaNodes.Get (nCsma)); serverApps.Start (Seconds (1.0)); serverApps.Stop (Seconds (10.0)); -@end verbatim And we put the echo client on the last STA node we created, pointing it to the server on the CSMA network. We have also seen similar operations before. -@verbatim +:: + UdpEchoClientHelper echoClient (csmaInterfaces.GetAddress (nCsma), 9); echoClient.SetAttribute ("MaxPackets", UintegerValue (1)); echoClient.SetAttribute ("Interval", TimeValue (Seconds (1.))); @@ -1158,17 +1130,16 @@ the server on the CSMA network. We have also seen similar operations before. echoClient.Install (wifiStaNodes.Get (nWifi - 1)); clientApps.Start (Seconds (2.0)); clientApps.Stop (Seconds (10.0)); -@end verbatim Since we have built an internetwork here, we need to enable internetwork routing -just as we did in the @code{second.cc} example script. +just as we did in the ``second.cc`` example script. + +:: -@verbatim Ipv4GlobalRoutingHelper::PopulateRoutingTables (); -@end verbatim One thing that can surprise some users is the fact that the simulation we just -created will never ``naturally'' stop. This is because we asked the wireless +created will never "naturally" stop. This is because we asked the wireless access point to generate beacons. It will generate beacons forever, and this will result in simulator events being scheduled into the future indefinitely, so we must tell the simulator to stop even though it may have beacon generation @@ -1176,17 +1147,17 @@ events scheduled. The following line of code tells the simulator to stop so tha we don't simulate beacons forever and enter what is essentially an endless loop. -@verbatim +:: + Simulator::Stop (Seconds (10.0)); -@end verbatim We create just enough tracing to cover all three networks: -@verbatim +:: + pointToPoint.EnablePcapAll ("third"); phy.EnablePcap ("third", apDevices.Get (0)); csma.EnablePcap ("third", csmaDevices.Get (0), true); -@end verbatim These three lines of code will start pcap tracing on both of the point-to-point nodes that serves as our backbone, will start a promiscuous (monitor) mode @@ -1196,69 +1167,70 @@ trace files. Finally, we actually run the simulation, clean up and then exit the program. -@verbatim +:: + Simulator::Run (); Simulator::Destroy (); return 0; } -@end verbatim -In order to run this example, you have to copy the @code{third.cc} example +In order to run this example, you have to copy the ``third.cc`` example script into the scratch directory and use Waf to build just as you did with -the @code{second.cc} example. If you are in the top-level directory of the +the ``second.cc`` example. If you are in the top-level directory of the repository you would type, -@verbatim +:: + cp examples/third.cc scratch/mythird.cc ./waf ./waf --run scratch/mythird -@end verbatim Again, since we have set up the UDP echo applications just as we did in the -@code{second.cc} script, you will see similar output. +``second.cc`` script, you will see similar output. + +:: -@verbatim Waf: Entering directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' 'build' finished successfully (0.407s) Sent 1024 bytes to 10.1.2.4 Received 1024 bytes from 10.1.3.3 Received 1024 bytes from 10.1.2.4 -@end verbatim -Recall that the first message, ``@code{Sent 1024 bytes to 10.1.2.4},'' is the +Recall that the first message, ``Sent 1024 bytes to 10.1.2.4``," is the UDP echo client sending a packet to the server. In this case, the client is on the wireless network (10.1.3.0). The second message, -``@code{Received 1024 bytes from 10.1.3.3},'' is from the UDP echo server, +"``Received 1024 bytes from 10.1.3.3``," is from the UDP echo server, generated when it receives the echo packet. The final message, -``@code{Received 1024 bytes from 10.1.2.4},'' is from the echo client, indicating +"``Received 1024 bytes from 10.1.2.4``," is from the echo client, indicating that it has received its echo back from the server. If you now go and look in the top level directory, you will find four trace files from this simulation, two from node zero and two from node one: -@verbatim -third-0-0.pcap third-0-1.pcap third-1-0.pcap third-1-1.pcap -@end verbatim +:: -The file ``third-0-0.pcap'' corresponds to the point-to-point device on node -zero -- the left side of the ``backbone''. The file ``third-1-0.pcap'' + third-0-0.pcap third-0-1.pcap third-1-0.pcap third-1-1.pcap + +The file "third-0-0.pcap" corresponds to the point-to-point device on node +zero -- the left side of the "backbone". The file "third-1-0.pcap" corresponds to the point-to-point device on node one -- the right side of the -``backbone''. The file ``third-0-1.pcap'' will be the promiscuous (monitor -mode) trace from the Wifi network and the file ``third-1-1.pcap'' will be the +"backbone". The file "third-0-1.pcap" will be the promiscuous (monitor +mode) trace from the Wifi network and the file "third-1-1.pcap" will be the promiscuous trace from the CSMA network. Can you verify this by inspecting the code? Since the echo client is on the Wifi network, let's start there. Let's take a look at the promiscuous (monitor mode) trace we captured on that network. -@verbatim +:: + tcpdump -nn -tt -r third-0-1.pcap -@end verbatim You should see some wifi-looking contents you haven't seen here before: -@verbatim +:: + reading from file third-0-1.pcap, link-type IEEE802_11 (802.11) 0.000025 Beacon () [6.0* 9.0 12.0 18.0 24.0 36.0 48.0 54.0 Mbit] IBSS 0.000263 Assoc Request () [6.0 9.0 12.0 18.0 24.0 36.0 48.0 54.0 Mbit] @@ -1288,7 +1260,6 @@ You should see some wifi-looking contents you haven't seen here before: 2.500000 Beacon () [6.0* 9.0 12.0 18.0 24.0 36.0 48.0 54.0 Mbit] IBSS 5.000000 Beacon () [6.0* 9.0 12.0 18.0 24.0 36.0 48.0 54.0 Mbit] IBSS 7.500000 Beacon () [6.0* 9.0 12.0 18.0 24.0 36.0 48.0 54.0 Mbit] IBSS -@end verbatim You can see that the link type is now 802.11 as you would expect. You can probably understand what is going on and find the IP echo request and response @@ -1297,34 +1268,34 @@ trace dump. Now, look at the pcap file of the right side of the point-to-point link, -@verbatim +:: + tcpdump -nn -tt -r third-0-0.pcap -@end verbatim Again, you should see some familiar looking contents: -@verbatim +:: + reading from file third-0-0.pcap, link-type PPP (PPP) 2.002169 IP 10.1.3.3.49153 > 10.1.2.4.9: UDP, length 1024 2.009771 IP 10.1.2.4.9 > 10.1.3.3.49153: UDP, length 1024 -@end verbatim This is the echo packet going from left to right (from Wifi to CSMA) and back again across the point-to-point link. Now, look at the pcap file of the right side of the point-to-point link, -@verbatim +:: + tcpdump -nn -tt -r third-1-0.pcap -@end verbatim Again, you should see some familiar looking contents: -@verbatim +:: + reading from file third-1-0.pcap, link-type PPP (PPP) 2.005855 IP 10.1.3.3.49153 > 10.1.2.4.9: UDP, length 1024 2.006084 IP 10.1.2.4.9 > 10.1.3.3.49153: UDP, length 1024 -@end verbatim This is also the echo packet going from left to right (from Wifi to CSMA) and back again across the point-to-point link with slightly different timings @@ -1333,13 +1304,14 @@ as you might expect. The echo server is on the CSMA network, let's look at the promiscuous trace there: -@verbatim +:: + tcpdump -nn -tt -r third-1-1.pcap -@end verbatim You should see some familiar looking contents: -@verbatim +:: + reading from file third-1-1.pcap, link-type EN10MB (Ethernet) 2.005855 arp who-has 10.1.2.4 (ff:ff:ff:ff:ff:ff) tell 10.1.2.1 2.005877 arp reply 10.1.2.4 is-at 00:00:00:00:00:06 @@ -1347,28 +1319,28 @@ You should see some familiar looking contents: 2.005980 arp who-has 10.1.2.1 (ff:ff:ff:ff:ff:ff) tell 10.1.2.4 2.005980 arp reply 10.1.2.1 is-at 00:00:00:00:00:03 2.006084 IP 10.1.2.4.9 > 10.1.3.3.49153: UDP, length 1024 -@end verbatim This should be easily understood. If you've forgotten, go back and look at -the discussion in @code{second.cc}. This is the same sequence. +the discussion in ``second.cc``. This is the same sequence. Now, we spent a lot of time setting up mobility models for the wireless network and so it would be a shame to finish up without even showing that the STA nodes are actually moving around during the simulation. Let's do this by hooking -into the @code{MobilityModel} course change trace source. This is just a sneak +into the ``MobilityModel`` course change trace source. This is just a sneak peek into the detailed tracing section which is coming up, but this seems a very nice place to get an example in. -As mentioned in the ``Tweaking ns-3'' section, the @command{ns-3} tracing system +As mentioned in the "Tweaking ns-3" section, the |ns3| tracing system is divided into trace sources and trace sinks, and we provide functions to connect the two. We will use the mobility model predefined course change trace source to originate the trace events. We will need to write a trace sink to connect to that source that will display some pretty information for us. Despite its reputation as being difficult, it's really quite simple. -Just before the main program of the @code{scratch/mythird.cc} script, add the +Just before the main program of the ``scratch/mythird.cc`` script, add the following function: -@verbatim +:: + void CourseChange (std::string context, Ptr model) { @@ -1376,51 +1348,51 @@ following function: NS_LOG_UNCOND (context << " x = " << position.x << ", y = " << position.y); } -@end verbatim This code just pulls the position information from the mobility model and unconditionally logs the x and y position of the node. We are going to arrange for this function to be called every time the wireless node with the echo client changes its position. We do this using the -@code{Config::Connect} function. Add the following lines of code to the -script just before the @code{Simulator::Run} call. +``Config::Connect`` function. Add the following lines of code to the +script just before the ``Simulator::Run`` call. + +:: -@verbatim std::ostringstream oss; oss << "/NodeList/" << wifiStaNodes.Get (nWifi - 1)->GetId () << "/$ns3::MobilityModel/CourseChange"; Config::Connect (oss.str (), MakeCallback (&CourseChange)); -@end verbatim What we do here is to create a string containing the tracing namespace path of the event to which we want to connect. First, we have to figure out which -node it is we want using the @code{GetId} method as described earlier. In the +node it is we want using the ``GetId`` method as described earlier. In the case of the default number of CSMA and wireless nodes, this turns out to be node seven and the tracing namespace path to the mobility model would look like, -@verbatim +:: + /NodeList/7/$ns3::MobilityModel/CourseChange -@end verbatim Based on the discussion in the tracing section, you may infer that this trace path references the seventh node in the global NodeList. It specifies -what is called an aggregated object of type @code{ns3::MobilityModel}. The +what is called an aggregated object of type ``ns3::MobilityModel``. The dollar sign prefix implies that the MobilityModel is aggregated to node seven. The last component of the path means that we are hooking into the -``CourseChange'' event of that model. +"CourseChange" event of that model. We make a connection between the trace source in node seven with our trace -sink by calling @code{Config::Connect} and passing this namespace path. Once +sink by calling ``Config::Connect`` and passing this namespace path. Once this is done, every course change event on node seven will be hooked into our trace sink, which will in turn print out the new position. If you now run the simulation, you will see the course changes displayed as they happen. -@verbatim +:: + Build finished successfully (00:00:01) /NodeList/7/$ns3::MobilityModel/CourseChange x = 10, y = 0 /NodeList/7/$ns3::MobilityModel/CourseChange x = 9.41539, y = -0.811313 @@ -1455,4 +1427,3 @@ they happen. /NodeList/7/$ns3::MobilityModel/CourseChange x = 7.33503, y = 2.30328 /NodeList/7/$ns3::MobilityModel/CourseChange x = 7.18682, y = 3.29223 /NodeList/7/$ns3::MobilityModel/CourseChange x = 7.96865, y = 2.66873 -@end verbatim diff --git a/doc/tutorial/source/conceptual-overview.rst b/doc/tutorial/source/conceptual-overview.rst new file mode 100644 index 000000000..d320047a9 --- /dev/null +++ b/doc/tutorial/source/conceptual-overview.rst @@ -0,0 +1,840 @@ +.. include:: replace.txt + + +Conceptual Overview +------------------- + +The first thing we need to do before actually starting to look at or write +|ns3| code is to explain a few core concepts and abstractions in the +system. Much of this may appear transparently obvious to some, but we +recommend taking the time to read through this section just to ensure you +are starting on a firm foundation. + +Key Abstractions +**************** + +In this section, we'll review some terms that are commonly used in +networking, but have a specific meaning in |ns3|. + +Node +++++ +In Internet jargon, a computing device that connects to a network is called +a *host* or sometimes an *end system*. Because |ns3| is a +*network* simulator, not specifically an *Internet* simulator, we +intentionally do not use the term host since it is closely associated with +the Internet and its protocols. Instead, we use a more generic term also +used by other simulators that originates in Graph Theory --- the *node*. + +In |ns3| the basic computing device abstraction is called the +node. This abstraction is represented in C++ by the class ``Node``. The +``Node`` class provides methods for managing the representations of +computing devices in simulations. + +You should think of a ``Node`` as a computer to which you will add +functionality. One adds things like applications, protocol stacks and +peripheral cards with their associated drivers to enable the computer to do +useful work. We use the same basic model in |ns3|. + +Application ++++++++++++ +Typically, computer software is divided into two broad classes. *System +Software* organizes various computer resources such as memory, processor +cycles, disk, network, etc., according to some computing model. System +software usually does not use those resources to complete tasks that directly +benefit a user. A user would typically run an *application* that acquires +and uses the resources controlled by the system software to accomplish some +goal. + +Often, the line of separation between system and application software is made +at the privilege level change that happens in operating system traps. +In |ns3| there is no real concept of operating system and especially +no concept of privilege levels or system calls. We do, however, have the +idea of an application. Just as software applications run on computers to +perform tasks in the "real world," |ns3| applications run on +|ns3| ``Nodes`` to drive simulations in the simulated world. + +In |ns3| the basic abstraction for a user program that generates some +activity to be simulated is the application. This abstraction is represented +in C++ by the class ``Application``. The ``Application`` class provides +methods for managing the representations of our version of user-level +applications in simulations. Developers are expected to specialize the +``Application`` class in the object-oriented programming sense to create new +applications. In this tutorial, we will use specializations of class +``Application`` called ``UdpEchoClientApplication`` and +``UdpEchoServerApplication``. As you might expect, these applications +compose a client/server application set used to generate and echo simulated +network packets + +Channel ++++++++ + +In the real world, one can connect a computer to a network. Often the media +over which data flows in these networks are called *channels*. When +you connect your Ethernet cable to the plug in the wall, you are connecting +your computer to an Ethernet communication channel. In the simulated world +of |ns3|, one connects a ``Node`` to an object representing a +communication channel. Here the basic communication subnetwork abstraction +is called the channel and is represented in C++ by the class ``Channel``. + +The ``Channel`` class provides methods for managing communication +subnetwork objects and connecting nodes to them. ``Channels`` may also be +specialized by developers in the object oriented programming sense. A +``Channel`` specialization may model something as simple as a wire. The +specialized ``Channel`` can also model things as complicated as a large +Ethernet switch, or three-dimensional space full of obstructions in the case +of wireless networks. + +We will use specialized versions of the ``Channel`` called +``CsmaChannel``, ``PointToPointChannel`` and ``WifiChannel`` in this +tutorial. The ``CsmaChannel``, for example, models a version of a +communication subnetwork that implements a *carrier sense multiple +access* communication medium. This gives us Ethernet-like functionality. + +Net Device +++++++++++ +It used to be the case that if you wanted to connect a computers to a network, +you had to buy a specific kind of network cable and a hardware device called +(in PC terminology) a *peripheral card* that needed to be installed in +your computer. If the peripheral card implemented some networking function, +they were called Network Interface Cards, or *NICs*. Today most +computers come with the network interface hardware built in and users don't +see these building blocks. + +A NIC will not work without a software driver to control the hardware. In +Unix (or Linux), a piece of peripheral hardware is classified as a +*device*. Devices are controlled using *device drivers*, and network +devices (NICs) are controlled using *network device drivers* +collectively known as *net devices*. In Unix and Linux you refer +to these net devices by names such as *eth0*. + +In |ns3| the *net device* abstraction covers both the software +driver and the simulated hardware. A net device is "installed" in a +``Node`` in order to enable the ``Node`` to communicate with other +``Nodes`` in the simulation via ``Channels``. Just as in a real +computer, a ``Node`` may be connected to more than one ``Channel`` via +multiple ``NetDevices``. + +The net device abstraction is represented in C++ by the class ``NetDevice``. +The ``NetDevice`` class provides methods for managing connections to +``Node`` and ``Channel`` objects; and may be specialized by developers +in the object-oriented programming sense. We will use the several specialized +versions of the ``NetDevice`` called ``CsmaNetDevice``, +``PointToPointNetDevice``, and ``WifiNetDevice`` in this tutorial. +Just as an Ethernet NIC is designed to work with an Ethernet network, the +``CsmaNetDevice`` is designed to work with a ``CsmaChannel``; the +``PointToPointNetDevice`` is designed to work with a +``PointToPointChannel`` and a ``WifiNetNevice`` is designed to work with +a ``WifiChannel``. + +Topology Helpers +++++++++++++++++ +In a real network, you will find host computers with added (or built-in) +NICs. In |ns3| we would say that you will find ``Nodes`` with +attached ``NetDevices``. In a large simulated network you will need to +arrange many connections between ``Nodes``, ``NetDevices`` and +``Channels``. + +Since connecting ``NetDevices`` to ``Nodes``, ``NetDevices`` +to ``Channels``, assigning IP addresses, etc., are such common tasks +in |ns3|, we provide what we call *topology helpers* to make +this as easy as possible. For example, it may take many distinct +|ns3| core operations to create a NetDevice, add a MAC address, +install that net device on a ``Node``, configure the node's protocol stack, +and then connect the ``NetDevice`` to a ``Channel``. Even more +operations would be required to connect multiple devices onto multipoint +channels and then to connect individual networks together into internetworks. +We provide topology helper objects that combine those many distinct operations +into an easy to use model for your convenience. + +A First ns-3 Script +******************* +If you downloaded the system as was suggested above, you will have a release +of |ns3| in a directory called ``repos`` under your home +directory. Change into that release directory, and you should find a +directory structure something like the following: + +:: + + AUTHORS doc/ README src/ waf.bat* + bindings/ examples/ RELEASE_NOTES utils/ wscript + build/ LICENSE samples/ VERSION wutils.py + CHANGES.html ns3/ scratch/ waf* wutils.pyc + +Change into the ``examples/tutorial`` directory. You should see a file named +``first.cc`` located there. This is a script that will create a simple +point-to-point link between two nodes and echo a single packet between the +nodes. Let's take a look at that script line by line, so go ahead and open +``first.cc`` in your favorite editor. + +Boilerplate ++++++++++++ +The first line in the file is an emacs mode line. This tells emacs about the +formatting conventions (coding style) we use in our source code. + +:: + + /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */ + +This is always a somewhat controversial subject, so we might as well get it +out of the way immediately. The |ns3| project, like most large +projects, has adopted a coding style to which all contributed code must +adhere. If you want to contribute your code to the project, you will +eventually have to conform to the |ns3| coding standard as described +in the file ``doc/codingstd.txt`` or shown on the project web page +`here +`_. + +We recommend that you, well, just get used to the look and feel of |ns3| +code and adopt this standard whenever you are working with our code. All of +the development team and contributors have done so with various amounts of +grumbling. The emacs mode line above makes it easier to get the formatting +correct if you use the emacs editor. + +The |ns3| simulator is licensed using the GNU General Public +License. You will see the appropriate GNU legalese at the head of every file +in the |ns3| distribution. Often you will see a copyright notice for +one of the institutions involved in the |ns3| project above the GPL +text and an author listed below. + +:: + + /* + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation; + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +Module Includes ++++++++++++++++ +The code proper starts with a number of include statements. + +:: + + #include "ns3/core-module.h" + #include "ns3/simulator-module.h" + #include "ns3/node-module.h" + #include "ns3/helper-module.h" + +To help our high-level script users deal with the large number of include +files present in the system, we group includes according to relatively large +modules. We provide a single include file that will recursively load all of +the include files used in each module. Rather than having to look up exactly +what header you need, and possibly have to get a number of dependencies right, +we give you the ability to load a group of files at a large granularity. This +is not the most efficient approach but it certainly makes writing scripts much +easier. + +Each of the |ns3| include files is placed in a directory called +``ns3`` (under the build directory) during the build process to help avoid +include file name collisions. The ``ns3/core-module.h`` file corresponds +to the ns-3 module you will find in the directory ``src/core`` in your +downloaded release distribution. If you list this directory you will find a +large number of header files. When you do a build, Waf will place public +header files in an ``ns3`` directory under the appropriate +``build/debug`` or ``build/optimized`` directory depending on your +configuration. Waf will also automatically generate a module include file to +load all of the public header files. + +Since you are, of course, following this tutorial religiously, you will +already have done a + +:: + + ./waf -d debug configure + +in order to configure the project to perform debug builds. You will also have +done a + +:: + + ./waf + +to build the project. So now if you look in the directory +``../../build/debug/ns3`` you will find the four module include files shown +above. You can take a look at the contents of these files and find that they +do include all of the public include files in their respective modules. + +Ns3 Namespace ++++++++++++++ +The next line in the ``first.cc`` script is a namespace declaration. + +:: + + using namespace ns3; + +The |ns3| project is implemented in a C++ namespace called +``ns3``. This groups all |ns3|-related declarations in a scope +outside the global namespace, which we hope will help with integration with +other code. The C++ ``using`` statement introduces the |ns3| +namespace into the current (global) declarative region. This is a fancy way +of saying that after this declaration, you will not have to type ``ns3::`` +scope resolution operator before all of the |ns3| code in order to use +it. If you are unfamiliar with namespaces, please consult almost any C++ +tutorial and compare the ``ns3`` namespace and usage here with instances of +the ``std`` namespace and the ``using namespace std;`` statements you +will often find in discussions of ``cout`` and streams. + +Logging ++++++++ +The next line of the script is the following, + +:: + + NS_LOG_COMPONENT_DEFINE ("FirstScriptExample"); + +We will use this statement as a convenient place to talk about our Doxygen +documentation system. If you look at the project web site, +`ns-3 project +`_, you will find a link to "Doxygen +(ns-3-dev)" in the navigation bar. If you select this link, you will be +taken to our documentation page for the current development release. There +is also a link to "Doxygen (stable)" that will take you to the documentation +for the latest stable release of |ns3|. + +Along the left side, you will find a graphical representation of the structure +of the documentation. A good place to start is the ``NS-3 Modules`` +"book" in the |ns3| navigation tree. If you expand ``Modules`` +you will see a list of |ns3| module documentation. The concept of +module here ties directly into the module include files discussed above. It +turns out that the |ns3| logging subsystem is part of the ``core`` +module, so go ahead and expand that documentation node. Now, expand the +``Debugging`` book and then select the ``Logging`` page. + +You should now be looking at the Doxygen documentation for the Logging module. +In the list of ``#define``s at the top of the page you will see the entry +for ``NS_LOG_COMPONENT_DEFINE``. Before jumping in, it would probably be +good to look for the "Detailed Description" of the logging module to get a +feel for the overall operation. You can either scroll down or select the +"More..." link under the collaboration diagram to do this. + +Once you have a general idea of what is going on, go ahead and take a look at +the specific ``NS_LOG_COMPONENT_DEFINE`` documentation. I won't duplicate +the documentation here, but to summarize, this line declares a logging +component called ``FirstScriptExample`` that allows you to enable and +disable console message logging by reference to the name. + +Main Function ++++++++++++++ +The next lines of the script you will find are, + +:: + + int + main (int argc, char *argv[]) + { + +This is just the declaration of the main function of your program (script). +Just as in any C++ program, you need to define a main function that will be +the first function run. There is nothing at all special here. Your +|ns3| script is just a C++ program. + +The next two lines of the script are used to enable two logging components that +are built into the Echo Client and Echo Server applications: + +:: + + LogComponentEnable("UdpEchoClientApplication", LOG_LEVEL_INFO); + LogComponentEnable("UdpEchoServerApplication", LOG_LEVEL_INFO); + +If you have read over the Logging component documentation you will have seen +that there are a number of levels of logging verbosity/detail that you can +enable on each component. These two lines of code enable debug logging at the +INFO level for echo clients and servers. This will result in the application +printing out messages as packets are sent and received during the simulation. + +Now we will get directly to the business of creating a topology and running +a simulation. We use the topology helper objects to make this job as +easy as possible. + +Topology Helpers +++++++++++++++++ +NodeContainer +~~~~~~~~~~~~~ +The next two lines of code in our script will actually create the +|ns3| ``Node`` objects that will represent the computers in the +simulation. + +:: + + NodeContainer nodes; + nodes.Create (2); + +Let's find the documentation for the ``NodeContainer`` class before we +continue. Another way to get into the documentation for a given class is via +the ``Classes`` tab in the Doxygen pages. If you still have the Doxygen +handy, just scroll up to the top of the page and select the ``Classes`` +tab. You should see a new set of tabs appear, one of which is +``Class List``. Under that tab you will see a list of all of the +|ns3| classes. Scroll down, looking for ``ns3::NodeContainer``. +When you find the class, go ahead and select it to go to the documentation for +the class. + +You may recall that one of our key abstractions is the ``Node``. This +represents a computer to which we are going to add things like protocol stacks, +applications and peripheral cards. The ``NodeContainer`` topology helper +provides a convenient way to create, manage and access any ``Node`` objects +that we create in order to run a simulation. The first line above just +declares a NodeContainer which we call ``nodes``. The second line calls the +``Create`` method on the ``nodes`` object and asks the container to +create two nodes. As described in the Doxygen, the container calls down into +the |ns3| system proper to create two ``Node`` objects and stores +pointers to those objects internally. + +The nodes as they stand in the script do nothing. The next step in +constructing a topology is to connect our nodes together into a network. +The simplest form of network we support is a single point-to-point link +between two nodes. We'll construct one of those links here. + +PointToPointHelper +~~~~~~~~~~~~~~~~~~ +We are constructing a point to point link, and, in a pattern which will become +quite familiar to you, we use a topology helper object to do the low-level +work required to put the link together. Recall that two of our key +abstractions are the ``NetDevice`` and the ``Channel``. In the real +world, these terms correspond roughly to peripheral cards and network cables. +Typically these two things are intimately tied together and one cannot expect +to interchange, for example, Ethernet devices and wireless channels. Our +Topology Helpers follow this intimate coupling and therefore you will use a +single ``PointToPointHelper`` to configure and connect |ns3| +``PointToPointNetDevice`` and ``PointToPointChannel`` objects in this +script. + +The next three lines in the script are, + +:: + + PointToPointHelper pointToPoint; + pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("5Mbps")); + pointToPoint.SetChannelAttribute ("Delay", StringValue ("2ms")); + +The first line, + +:: + + PointToPointHelper pointToPoint; + +instantiates a ``PointToPointHelper`` object on the stack. From a +high-level perspective the next line, + +:: + + pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("5Mbps")); + +tells the ``PointToPointHelper`` object to use the value "5Mbps" +(five megabits per second) as the "DataRate" when it creates a +``PointToPointNetDevice`` object. + +From a more detailed perspective, the string "DataRate" corresponds +to what we call an ``Attribute`` of the ``PointToPointNetDevice``. +If you look at the Doxygen for class ``ns3::PointToPointNetDevice`` and +find the documentation for the ``GetTypeId`` method, you will find a list +of ``Attributes`` defined for the device. Among these is the "DataRate" +``Attribute``. Most user-visible |ns3| objects have similar lists of +``Attributes``. We use this mechanism to easily configure simulations without +recompiling as you will see in a following section. + +Similar to the "DataRate" on the ``PointToPointNetDevice`` you will find a +"Delay" ``Attribute`` associated with the ``PointToPointChannel``. The +final line, + +:: + + pointToPoint.SetChannelAttribute ("Delay", StringValue ("2ms")); + +tells the ``PointToPointHelper`` to use the value "2ms" (two milliseconds) +as the value of the transmission delay of every point to point channel it +subsequently creates. + +NetDeviceContainer +~~~~~~~~~~~~~~~~~~ +At this point in the script, we have a ``NodeContainer`` that contains +two nodes. We have a ``PointToPointHelper`` that is primed and ready to +make ``PointToPointNetDevices`` and wire ``PointToPointChannel`` objects +between them. Just as we used the ``NodeContainer`` topology helper object +to create the ``Nodes`` for our simulation, we will ask the +``PointToPointHelper`` to do the work involved in creating, configuring and +installing our devices for us. We will need to have a list of all of the +NetDevice objects that are created, so we use a NetDeviceContainer to hold +them just as we used a NodeContainer to hold the nodes we created. The +following two lines of code, + +:: + + NetDeviceContainer devices; + devices = pointToPoint.Install (nodes); + +will finish configuring the devices and channel. The first line declares the +device container mentioned above and the second does the heavy lifting. The +``Install`` method of the ``PointToPointHelper`` takes a +``NodeContainer`` as a parameter. Internally, a ``NetDeviceContainer`` +is created. For each node in the ``NodeContainer`` (there must be exactly +two for a point-to-point link) a ``PointToPointNetDevice`` is created and +saved in the device container. A ``PointToPointChannel`` is created and +the two ``PointToPointNetDevices`` are attached. When objects are created +by the ``PointToPointHelper``, the ``Attributes`` previously set in the +helper are used to initialize the corresponding ``Attributes`` in the +created objects. + +After executing the ``pointToPoint.Install (nodes)`` call we will have +two nodes, each with an installed point-to-point net device and a single +point-to-point channel between them. Both devices will be configured to +transmit data at five megabits per second over the channel which has a two +millisecond transmission delay. + +InternetStackHelper +~~~~~~~~~~~~~~~~~~~ +We now have nodes and devices configured, but we don't have any protocol stacks +installed on our nodes. The next two lines of code will take care of that. + +:: + + InternetStackHelper stack; + stack.Install (nodes); + +The ``InternetStackHelper`` is a topology helper that is to internet stacks +what the ``PointToPointHelper`` is to point-to-point net devices. The +``Install`` method takes a ``NodeContainer`` as a parameter. When it is +executed, it will install an Internet Stack (TCP, UDP, IP, etc.) on each of +the nodes in the node container. + +Ipv4AddressHelper +~~~~~~~~~~~~~~~~~ +Next we need to associate the devices on our nodes with IP addresses. We +provide a topology helper to manage the allocation of IP addresses. The only +user-visible API is to set the base IP address and network mask to use when +performing the actual address allocation (which is done at a lower level +inside the helper). + +The next two lines of code in our example script, ``first.cc``, + +:: + + Ipv4AddressHelper address; + address.SetBase ("10.1.1.0", "255.255.255.0"); + +declare an address helper object and tell it that it should begin allocating IP +addresses from the network 10.1.1.0 using the mask 255.255.255.0 to define +the allocatable bits. By default the addresses allocated will start at one +and increase monotonically, so the first address allocated from this base will +be 10.1.1.1, followed by 10.1.1.2, etc. The low level |ns3| system +actually remembers all of the IP addresses allocated and will generate a +fatal error if you accidentally cause the same address to be generated twice +(which is a very hard to debug error, by the way). + +The next line of code, + +:: + + Ipv4InterfaceContainer interfaces = address.Assign (devices); + +performs the actual address assignment. In |ns3| we make the +association between an IP address and a device using an ``Ipv4Interface`` +object. Just as we sometimes need a list of net devices created by a helper +for future reference we sometimes need a list of ``Ipv4Interface`` objects. +The ``Ipv4InterfaceContainer`` provides this functionality. + +Now we have a point-to-point network built, with stacks installed and IP +addresses assigned. What we need at this point are applications to generate +traffic. + +Applications +++++++++++++ +Another one of the core abstractions of the ns-3 system is the +``Application``. In this script we use two specializations of the core +|ns3| class ``Application`` called ``UdpEchoServerApplication`` +and ``UdpEchoClientApplication``. Just as we have in our previous +explanations, we use helper objects to help configure and manage the +underlying objects. Here, we use ``UdpEchoServerHelper`` and +``UdpEchoClientHelper`` objects to make our lives easier. + +UdpEchoServerHelper +~~~~~~~~~~~~~~~~~~~ +The following lines of code in our example script, ``first.cc``, are used +to set up a UDP echo server application on one of the nodes we have previously +created. + +:: + + UdpEchoServerHelper echoServer (9); + + ApplicationContainer serverApps = echoServer.Install (nodes.Get (1)); + serverApps.Start (Seconds (1.0)); + serverApps.Stop (Seconds (10.0)); + +The first line of code in the above snippet declares the +``UdpEchoServerHelper``. As usual, this isn't the application itself, it +is an object used to help us create the actual applications. One of our +conventions is to place *required* ``Attributes`` in the helper constructor. +In this case, the helper can't do anything useful unless it is provided with +a port number that the client also knows about. Rather than just picking one +and hoping it all works out, we require the port number as a parameter to the +constructor. The constructor, in turn, simply does a ``SetAttribute`` +with the passed value. If you want, you can set the "Port" ``Attribute`` +to another value later using ``SetAttribute``. + +Similar to many other helper objects, the ``UdpEchoServerHelper`` object +has an ``Install`` method. It is the execution of this method that actually +causes the underlying echo server application to be instantiated and attached +to a node. Interestingly, the ``Install`` method takes a +``NodeContainter`` as a parameter just as the other ``Install`` methods +we have seen. This is actually what is passed to the method even though it +doesn't look so in this case. There is a C++ *implicit conversion* at +work here that takes the result of ``nodes.Get (1)`` (which returns a smart +pointer to a node object --- ``Ptr``) and uses that in a constructor +for an unnamed ``NodeContainer`` that is then passed to ``Install``. +If you are ever at a loss to find a particular method signature in C++ code +that compiles and runs just fine, look for these kinds of implicit conversions. + +We now see that ``echoServer.Install`` is going to install a +``UdpEchoServerApplication`` on the node found at index number one of the +``NodeContainer`` we used to manage our nodes. ``Install`` will return +a container that holds pointers to all of the applications (one in this case +since we passed a ``NodeContainer`` containing one node) created by the +helper. + +Applications require a time to "start" generating traffic and may take an +optional time to "stop". We provide both. These times are set using the +``ApplicationContainer`` methods ``Start`` and ``Stop``. These +methods take ``Time`` parameters. In this case, we use an *explicit* +C++ conversion sequence to take the C++ double 1.0 and convert it to an +|ns3| ``Time`` object using a ``Seconds`` cast. Be aware that +the conversion rules may be controlled by the model author, and C++ has its +own rules, so you can't always just assume that parameters will be happily +converted for you. The two lines, + +:: + + serverApps.Start (Seconds (1.0)); + serverApps.Stop (Seconds (10.0)); + +will cause the echo server application to ``Start`` (enable itself) at one +second into the simulation and to ``Stop`` (disable itself) at ten seconds +into the simulation. By virtue of the fact that we have declared a simulation +event (the application stop event) to be executed at ten seconds, the simulation +will last *at least* ten seconds. + +UdpEchoClientHelper +~~~~~~~~~~~~~~~~~~~ + +The echo client application is set up in a method substantially similar to +that for the server. There is an underlying ``UdpEchoClientApplication`` +that is managed by an ``UdpEchoClientHelper``. + +:: + + UdpEchoClientHelper echoClient (interfaces.GetAddress (1), 9); + echoClient.SetAttribute ("MaxPackets", UintegerValue (1)); + echoClient.SetAttribute ("Interval", TimeValue (Seconds (1.))); + echoClient.SetAttribute ("PacketSize", UintegerValue (1024)); + + ApplicationContainer clientApps = echoClient.Install (nodes.Get (0)); + clientApps.Start (Seconds (2.0)); + clientApps.Stop (Seconds (10.0)); + +For the echo client, however, we need to set five different ``Attributes``. +The first two ``Attributes`` are set during construction of the +``UdpEchoClientHelper``. We pass parameters that are used (internally to +the helper) to set the "RemoteAddress" and "RemotePort" ``Attributes`` +in accordance with our convention to make required ``Attributes`` parameters +in the helper constructors. + +Recall that we used an ``Ipv4InterfaceContainer`` to keep track of the IP +addresses we assigned to our devices. The zeroth interface in the +``interfaces`` container is going to correspond to the IP address of the +zeroth node in the ``nodes`` container. The first interface in the +``interfaces`` container corresponds to the IP address of the first node +in the ``nodes`` container. So, in the first line of code (from above), we +are creating the helper and telling it so set the remote address of the client +to be the IP address assigned to the node on which the server resides. We +also tell it to arrange to send packets to port nine. + +The "MaxPackets" ``Attribute`` tells the client the maximum number of +packets we allow it to send during the simulation. The "Interval" +``Attribute`` tells the client how long to wait between packets, and the +"PacketSize" ``Attribute`` tells the client how large its packet payloads +should be. With this particular combination of ``Attributes``, we are +telling the client to send one 1024-byte packet. + +Just as in the case of the echo server, we tell the echo client to ``Start`` +and ``Stop``, but here we start the client one second after the server is +enabled (at two seconds into the simulation). + +Simulator ++++++++++ +What we need to do at this point is to actually run the simulation. This is +done using the global function ``Simulator::Run``. + +:: + + Simulator::Run (); + +When we previously called the methods, + +:: + + serverApps.Start (Seconds (1.0)); + serverApps.Stop (Seconds (10.0)); + ... + clientApps.Start (Seconds (2.0)); + clientApps.Stop (Seconds (10.0)); + +we actually scheduled events in the simulator at 1.0 seconds, 2.0 seconds and +two events at 10.0 seconds. When ``Simulator::Run`` is called, the system +will begin looking through the list of scheduled events and executing them. +First it will run the event at 1.0 seconds, which will enable the echo server +application (this event may, in turn, schedule many other events). Then it +will run the event scheduled for t=2.0 seconds which will start the echo client +application. Again, this event may schedule many more events. The start event +implementation in the echo client application will begin the data transfer phase +of the simulation by sending a packet to the server. + +The act of sending the packet to the server will trigger a chain of events +that will be automatically scheduled behind the scenes and which will perform +the mechanics of the packet echo according to the various timing parameters +that we have set in the script. + +Eventually, since we only send one packet (recall the ``MaxPackets`` +``Attribute`` was set to one), the chain of events triggered by +that single client echo request will taper off and the simulation will go +idle. Once this happens, the remaining events will be the ``Stop`` events +for the server and the client. When these events are executed, there are +no further events to process and ``Simulator::Run`` returns. The simulation +is then complete. + +All that remains is to clean up. This is done by calling the global function +``Simulator::Destroy``. As the helper functions (or low level +|ns3| code) executed, they arranged it so that hooks were inserted in +the simulator to destroy all of the objects that were created. You did not +have to keep track of any of these objects yourself --- all you had to do +was to call ``Simulator::Destroy`` and exit. The |ns3| system +took care of the hard part for you. The remaining lines of our first +|ns3| script, ``first.cc``, do just that: + +:: + + Simulator::Destroy (); + return 0; + } + +Building Your Script +++++++++++++++++++++ +We have made it trivial to build your simple scripts. All you have to do is +to drop your script into the scratch directory and it will automatically be +built if you run Waf. Let's try it. Copy ``examples/tutorial/first.cc`` into +the ``scratch`` directory after changing back into the top level directory. + +:: + + cd .. + cp examples/tutorial/first.cc scratch/myfirst.cc + +Now build your first example script using waf: + +:: + + ./waf + +You should see messages reporting that your ``myfirst`` example was built +successfully. + +:: + + Waf: Entering directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' + [614/708] cxx: scratch/myfirst.cc -> build/debug/scratch/myfirst_3.o + [706/708] cxx_link: build/debug/scratch/myfirst_3.o -> build/debug/scratch/myfirst + Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' + 'build' finished successfully (2.357s) + +You can now run the example (note that if you build your program in the scratch +directory you must run it out of the scratch directory): + +:: + + ./waf --run scratch/myfirst + +You should see some output: + +:: + + Waf: Entering directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' + Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' + 'build' finished successfully (0.418s) + Sent 1024 bytes to 10.1.1.2 + Received 1024 bytes from 10.1.1.1 + Received 1024 bytes from 10.1.1.2 + +Here you see that the build system checks to make sure that the file has been +build and then runs it. You see the logging component on the echo client +indicate that it has sent one 1024 byte packet to the Echo Server on +10.1.1.2. You also see the logging component on the echo server say that +it has received the 1024 bytes from 10.1.1.1. The echo server silently +echoes the packet and you see the echo client log that it has received its +packet back from the server. + +Ns-3 Source Code +**************** + +Now that you have used some of the |ns3| helpers you may want to +have a look at some of the source code that implements that functionality. +The most recent code can be browsed on our web server at the following link: +http://code.nsnam.org/ns-3-dev. There, you will see the Mercurial +summary page for our |ns3| development tree. + +At the top of the page, you will see a number of links, + +:: + + summary | shortlog | changelog | graph | tags | files + +Go ahead and select the ``files`` link. This is what the top-level of +most of our *repositories* will look: + +:: + + drwxr-xr-x [up] + drwxr-xr-x bindings python files + drwxr-xr-x doc files + drwxr-xr-x examples files + drwxr-xr-x ns3 files + drwxr-xr-x samples files + drwxr-xr-x scratch files + drwxr-xr-x src files + drwxr-xr-x utils files + -rw-r--r-- 2009-07-01 12:47 +0200 560 .hgignore file | revisions | annotate + -rw-r--r-- 2009-07-01 12:47 +0200 1886 .hgtags file | revisions | annotate + -rw-r--r-- 2009-07-01 12:47 +0200 1276 AUTHORS file | revisions | annotate + -rw-r--r-- 2009-07-01 12:47 +0200 30961 CHANGES.html file | revisions | annotate + -rw-r--r-- 2009-07-01 12:47 +0200 17987 LICENSE file | revisions | annotate + -rw-r--r-- 2009-07-01 12:47 +0200 3742 README file | revisions | annotate + -rw-r--r-- 2009-07-01 12:47 +0200 16171 RELEASE_NOTES file | revisions | annotate + -rw-r--r-- 2009-07-01 12:47 +0200 6 VERSION file | revisions | annotate + -rwxr-xr-x 2009-07-01 12:47 +0200 88110 waf file | revisions | annotate + -rwxr-xr-x 2009-07-01 12:47 +0200 28 waf.bat file | revisions | annotate + -rw-r--r-- 2009-07-01 12:47 +0200 35395 wscript file | revisions | annotate + -rw-r--r-- 2009-07-01 12:47 +0200 7673 wutils.py file | revisions | annotate + +Our example scripts are in the ``examples`` directory. If you click on ``examples`` +you will see a list of files. One of the files in that directory is ``first.cc``. If +you click on ``first.cc`` you will find the code you just walked through. + +The source code is mainly in the ``src`` directory. You can view source +code either by clicking on the directory name or by clicking on the ``files`` +link to the right of the directory name. If you click on the ``src`` +directory, you will be taken to the listing of the ``src`` subdirectories. If you +then click on ``core`` subdirectory, you will find a list of files. The first file +you will find (as of this writing) is ``abort.h``. If you click on the +``abort.h`` link, you will be sent to the source file for ``abort.h`` which +contains useful macros for exiting scripts if abnormal conditions are detected. + +The source code for the helpers we have used in this chapter can be found in the +``src/helper`` directory. Feel free to poke around in the directory tree to +get a feel for what is there and the style of |ns3| programs. diff --git a/doc/tutorial/source/conclusion.rst b/doc/tutorial/source/conclusion.rst new file mode 100644 index 000000000..53be0d3f3 --- /dev/null +++ b/doc/tutorial/source/conclusion.rst @@ -0,0 +1,37 @@ +.. include:: replace.txt + + +Conclusion +---------- + +Futures +******* + +This document is a work in process. We hope and expect it to grow over time +to cover more and more of the nuts and bolts of |ns3|. + +We hope to add the following chapters over the next few releases: + +* The Callback System +* The Object System and Memory Management +* The Routing System +* Adding a New NetDevice and Channel +* Adding a New Protocol +* Working with Real Networks and Hosts + +Writing manual and tutorial chapters is not something we all get excited about, +but it is very important to the project. If you are an expert in one of these +areas, please consider contributing to |ns3| by providing one of these +chapters; or any other chapter you may think is important. + +Closing +******* + +|ns3| is a large and complicated system. It is impossible to cover all +of the things you will need to know in one small tutorial. + +We have really just scratched the surface of |ns3| in this tutorial, +but we hope to have covered enough to get you started doing useful networking +research using our favorite simulator. + +-- The |ns3| development team. diff --git a/doc/tutorial/source/conf.py b/doc/tutorial/source/conf.py new file mode 100644 index 000000000..41c66bd6e --- /dev/null +++ b/doc/tutorial/source/conf.py @@ -0,0 +1,216 @@ +# -*- coding: utf-8 -*- +# +# ns-3 documentation build configuration file, created by +# sphinx-quickstart on Tue Dec 14 09:00:39 2010. +# +# This file is execfile()d with the current directory set to its containing dir. +# +# Note that not all possible configuration values are present in this +# autogenerated file. +# +# All configuration values have a default; values that are commented out +# serve to show the default. + +import sys, os + +# If extensions (or modules to document with autodoc) are in another directory, +# add these directories to sys.path here. If the directory is relative to the +# documentation root, use os.path.abspath to make it absolute, like shown here. +#sys.path.insert(0, os.path.abspath('.')) + +# -- General configuration ----------------------------------------------------- + +# If your documentation needs a minimal Sphinx version, state it here. +#needs_sphinx = '1.0' + +# Add any Sphinx extension module names here, as strings. They can be extensions +# coming with Sphinx (named 'sphinx.ext.*') or your custom ones. +extensions = ['sphinx.ext.pngmath'] + +# Add any paths that contain templates here, relative to this directory. +templates_path = ['_templates'] + +# The suffix of source filenames. +source_suffix = '.rst' + +# The encoding of source files. +#source_encoding = 'utf-8-sig' + +# The master toctree document. +master_doc = 'index' + +# General information about the project. +project = u'ns-3' +copyright = u'2010, ns-3 project' + +# The version info for the project you're documenting, acts as replacement for +# |version| and |release|, also used in various other places throughout the +# built documents. +# +# The short X.Y version. +version = 'ns-3.10' +# The full version, including alpha/beta/rc tags. +release = 'ns-3.10' + +# The language for content autogenerated by Sphinx. Refer to documentation +# for a list of supported languages. +#language = None + +# There are two options for replacing |today|: either, you set today to some +# non-false value, then it is used: +#today = '' +# Else, today_fmt is used as the format for a strftime call. +#today_fmt = '%B %d, %Y' + +# List of patterns, relative to source directory, that match files and +# directories to ignore when looking for source files. +exclude_patterns = [] + +# The reST default role (used for this markup: `text`) to use for all documents. +#default_role = None + +# If true, '()' will be appended to :func: etc. cross-reference text. +#add_function_parentheses = True + +# If true, the current module name will be prepended to all description +# unit titles (such as .. function::). +#add_module_names = True + +# If true, sectionauthor and moduleauthor directives will be shown in the +# output. They are ignored by default. +#show_authors = False + +# The name of the Pygments (syntax highlighting) style to use. +pygments_style = 'sphinx' + +# A list of ignored prefixes for module index sorting. +#modindex_common_prefix = [] + + +# -- Options for HTML output --------------------------------------------------- + +# The theme to use for HTML and HTML Help pages. See the documentation for +# a list of builtin themes. +html_theme = 'default' + +# Theme options are theme-specific and customize the look and feel of a theme +# further. For a list of options available for each theme, see the +# documentation. +#html_theme_options = {} + +# Add any paths that contain custom themes here, relative to this directory. +#html_theme_path = [] + +# The name for this set of Sphinx documents. If None, it defaults to +# " v documentation". +#html_title = None + +# A shorter title for the navigation bar. Default is the same as html_title. +#html_short_title = None + +# The name of an image file (relative to this directory) to place at the top +# of the sidebar. +#html_logo = None + +# The name of an image file (within the static path) to use as favicon of the +# docs. This file should be a Windows icon file (.ico) being 16x16 or 32x32 +# pixels large. +#html_favicon = None + +# Add any paths that contain custom static files (such as style sheets) here, +# relative to this directory. They are copied after the builtin static files, +# so a file named "default.css" will overwrite the builtin "default.css". +html_static_path = ['_static'] + +# If not '', a 'Last updated on:' timestamp is inserted at every page bottom, +# using the given strftime format. +#html_last_updated_fmt = '%b %d, %Y' + +# If true, SmartyPants will be used to convert quotes and dashes to +# typographically correct entities. +#html_use_smartypants = True + +# Custom sidebar templates, maps document names to template names. +#html_sidebars = {} + +# Additional templates that should be rendered to pages, maps page names to +# template names. +#html_additional_pages = {} + +# If false, no module index is generated. +#html_domain_indices = True + +# If false, no index is generated. +#html_use_index = True + +# If true, the index is split into individual pages for each letter. +#html_split_index = False + +# If true, links to the reST sources are added to the pages. +#html_show_sourcelink = True + +# If true, "Created using Sphinx" is shown in the HTML footer. Default is True. +#html_show_sphinx = True + +# If true, "(C) Copyright ..." is shown in the HTML footer. Default is True. +#html_show_copyright = True + +# If true, an OpenSearch description file will be output, and all pages will +# contain a tag referring to it. The value of this option must be the +# base URL from which the finished HTML is served. +#html_use_opensearch = '' + +# This is the file name suffix for HTML files (e.g. ".xhtml"). +#html_file_suffix = None + +# Output file base name for HTML help builder. +htmlhelp_basename = 'ns-3doc' + + +# -- Options for LaTeX output -------------------------------------------------- + +# The paper size ('letter' or 'a4'). +#latex_paper_size = 'letter' + +# The font size ('10pt', '11pt' or '12pt'). +#latex_font_size = '10pt' + +# Grouping the document tree into LaTeX files. List of tuples +# (source start file, target name, title, author, documentclass [howto/manual]). +latex_documents = [ + ('index', 'ns-3.tex', u'ns-3 Tutorial', + u'ns-3 project', 'manual'), +] + +# The name of an image file (relative to this directory) to place at the top of +# the title page. +#latex_logo = None + +# For "manual" documents, if this is true, then toplevel headings are parts, +# not chapters. +#latex_use_parts = False + +# If true, show page references after internal links. +#latex_show_pagerefs = False + +# If true, show URL addresses after external links. +#latex_show_urls = False + +# Additional stuff for the LaTeX preamble. +#latex_preamble = '' + +# Documents to append as an appendix to all manuals. +#latex_appendices = [] + +# If false, no module index is generated. +#latex_domain_indices = True + + +# -- Options for manual page output -------------------------------------------- + +# One entry per manual page. List of tuples +# (source start file, name, description, authors, manual section). +man_pages = [ + ('index', 'ns-3', u'ns-3 Tutorial', + [u'ns-3 project'], 1) +] diff --git a/doc/tutorial/source/figures b/doc/tutorial/source/figures new file mode 120000 index 000000000..7edfd1af6 --- /dev/null +++ b/doc/tutorial/source/figures @@ -0,0 +1 @@ +../figures \ No newline at end of file diff --git a/doc/tutorial/getting-started.texi b/doc/tutorial/source/getting-started.rst similarity index 61% rename from doc/tutorial/getting-started.texi rename to doc/tutorial/source/getting-started.rst index ee44a9770..2d5009998 100644 --- a/doc/tutorial/getting-started.texi +++ b/doc/tutorial/source/getting-started.rst @@ -1,101 +1,71 @@ + .. include:: replace.txt -@c ======================================================================== -@c Begin document body here -@c ======================================================================== -@c ======================================================================== -@c PART: Getting Started -@c ======================================================================== -@c The below chapters are under the major heading "Getting Started" -@c This is similar to the Latex \part command -@c -@c ======================================================================== -@c Getting Started -@c ======================================================================== -@node Getting Started -@chapter Getting Started +Getting Started +--------------- -@menu -* Downloading ns-3:: -* Building ns-3:: -* Testing ns-3:: -* Running a Script:: -@end menu +Downloading ns-3 +**************** -@c ======================================================================== -@c Downloading ns-3 -@c ======================================================================== - -@node Downloading ns-3 -@section Downloading ns-3 - -@cindex Prerequisites -@cindex Dependencies -The @command{ns-3} system as a whole is a fairly complex system and has a +The |ns3| system as a whole is a fairly complex system and has a number of dependencies on other components. Along with the systems you will most likely deal with every day (the GNU toolchain, Mercurial, you programmer editor) you will need to ensure that a number of additional libraries are -present on your system before proceeding. @command{ns-3} provides a wiki +present on your system before proceeding. |ns3| provides a wiki for your reading pleasure that includes pages with many useful hints and tips. -One such page is the ``Installation'' page, -@uref{http://www.nsnam.org/wiki/index.php/Installation}. +One such page is the "Installation" page, +http://www.nsnam.org/wiki/index.php/Installation. -The ``Prerequisites'' section of this wiki page explains which packages are -required to support common @command{ns-3} options, and also provides the +The "Prerequisites" section of this wiki page explains which packages are +required to support common |ns3| options, and also provides the commands used to install them for common Linux variants. Cygwin users will have to use the Cygwin installer (if you are a Cygwin user, you used it to install Cygwin). -You may want to take this opportunity to explore the @command{ns-3} wiki +You may want to take this opportunity to explore the |ns3| wiki a bit since there really is a wealth of information there. -@cindex Linux -@cindex Cygwin -@cindex GNU -@cindex toolchain -@cindex Mercurial -@cindex Waf From this point forward, we are going to assume that the reader is working in Linux or a Linux emulation environment (Linux, Cygwin, etc.) and has the GNU toolchain installed and verified along with the prerequisites mentioned above. We are also going to assume that you have Mercurial and Waf installed -and running on the target system as described in the ``Getting Started'' section -of the @command{ns-3} web site: -@uref{http://www.nsnam.org/getting_started.html}. +and running on the target system as described in the "Getting Started" section +of the |ns3| web site: +http://www.nsnam.org/getting_started.html. -@cindex tarball -The @command{ns-3} code is available in Mercurial repositories on the server -@uref{http://code.nsnam.org}. You can also download a tarball release at -@uref{http://www.nsnam.org/releases/}, or you can work with repositories +The |ns3| code is available in Mercurial repositories on the server +http://code.nsnam.org. You can also download a tarball release at +http://www.nsnam.org/releases/, or you can work with repositories using Mercurial. We recommend using Mercurial unless there's a good reason not to. See the end of this section for instructions on how to get a tarball release. -@cindex repository The simplest way to get started using Mercurial repositories is to use the -@code{ns-3-allinone} environment. This is a set of scripts that manages the -downloading and building of various subsystems of @command{ns-3} for you. We -recommend that you begin your @command{ns-3} adventures in this environment +``ns-3-allinone`` environment. This is a set of scripts that manages the +downloading and building of various subsystems of |ns3| for you. We +recommend that you begin your |ns3| adventures in this environment as it can really simplify your life at this point. -@subsection Downloading ns-3 Using Mercurial -One practice is to create a directory called @code{repos} in one's home +Downloading ns-3 Using Mercurial +++++++++++++++++++++++++++++++++ +One practice is to create a directory called ``repos`` in one's home directory under which one can keep local Mercurial repositories. -@emph{Hint: we will assume you do this later in the tutorial.} If you adopt -that approach, you can get a copy of @code{ns-3-allinone} by typing the +*Hint: we will assume you do this later in the tutorial.* If you adopt +that approach, you can get a copy of ``ns-3-allinone`` by typing the following into your Linux shell (assuming you have installed Mercurial): -@verbatim +:: + cd mkdir repos cd repos hg clone http://code.nsnam.org/ns-3-allinone -@end verbatim As the hg (Mercurial) command executes, you should see something like the following displayed, -@verbatim +:: + destination directory: ns-3-allinone requesting all changes adding changesets @@ -103,31 +73,29 @@ following displayed, adding file changes added 31 changesets with 45 changes to 7 files 7 files updated, 0 files merged, 0 files removed, 0 files unresolved -@end verbatim After the clone command completes, you should have a directory called -@code{ns-3-allinone} under your @code{~/repos} directory, the contents of which should +``ns-3-allinone`` under your ``~/repos`` directory, the contents of which should look something like the following: -@verbatim +:: + build.py* constants.py dist.py* download.py* README util.py -@end verbatim Notice that you really just downloaded some Python scripts. The next step -will be to use those scripts to download and build the @command{ns-3} +will be to use those scripts to download and build the |ns3| distribution of your choice. -@cindex repository -If you go to the following link: @uref{http://code.nsnam.org/}, +If you go to the following link: http://code.nsnam.org/, you will see a number of repositories. Many are the private repositories of -the @command{ns-3} development team. The repositories of interest to you will -be prefixed with ``ns-3''. Official releases of @command{ns-3} will be -numbered as @code{ns-3..}. For example, a second hotfix to a -still hypothetical release nine of @command{ns-3} would be numbered as -@code{ns-3.9.2}. +the |ns3| development team. The repositories of interest to you will +be prefixed with "ns-3". Official releases of |ns3| will be +numbered as ``ns-3..``. For example, a second hotfix to a +still hypothetical release nine of |ns3| would be numbered as +``ns-3.9.2``. -The current development snapshot (unreleased) of @command{ns-3} may be found -at @uref{http://code.nsnam.org/ns-3-dev/}. The +The current development snapshot (unreleased) of |ns3| may be found +at http://code.nsnam.org/ns-3-dev/. The developers attempt to keep these repository in consistent, working states but they are in a development area with unreleased code present, so you may want to consider staying with an official release if you do not need newly- @@ -135,38 +103,40 @@ introduced features. Since the release numbers are going to be changing, I will stick with the more constant ns-3-dev here in the tutorial, but you can replace the -string ``ns-3-dev'' with your choice of release (e.g., ns-3.6) in the +string "ns-3-dev" with your choice of release (e.g., ns-3.10) in the text below. You can find the latest version of the code either by inspection of the repository list or by going to the -@uref{http://www.nsnam.org/getting_started.html,,``Getting Started''} +`"Getting Started" +`_ web page and looking for the latest release identifier. -Go ahead and change into the @code{ns-3-allinone} directory you created when -you cloned that repository. We are now going to use the @code{download.py} -script to pull down the various pieces of @command{ns-3} you will be using. +Go ahead and change into the ``ns-3-allinone`` directory you created when +you cloned that repository. We are now going to use the ``download.py`` +script to pull down the various pieces of |ns3| you will be using. Go ahead and type the following into your shell (remember you can substitute -the name of your chosen release number instead of @code{ns-3-dev} -- like -@code{"ns-3.6"} if you want to work with a +the name of your chosen release number instead of ``ns-3-dev`` -- like +``"ns-3.10"`` if you want to work with a stable release). -@verbatim - ./download.py -n ns-3-dev -@end verbatim +:: -Note that the default for the @code{-n} option is @code{ns-3-dev} and so the + ./download.py -n ns-3-dev + +Note that the default for the ``-n`` option is ``ns-3-dev`` and so the above is actually redundant. We provide this example to illustrate how to -specify alternate repositories. In order to download @code{ns-3-dev} you +specify alternate repositories. In order to download ``ns-3-dev`` you can actually use the defaults and simply type, -@verbatim +:: + ./download.py -@end verbatim As the hg (Mercurial) command executes, you should see something like the following, -@verbatim +:: + # # Get NS-3 # @@ -179,9 +149,8 @@ following, adding file changes added 4634 changesets with 16500 changes to 1762 files 870 files updated, 0 files merged, 0 files removed, 0 files unresolved -@end verbatim -This is output by the download script as it fetches the actual @code{ns-3} +This is output by the download script as it fetches the actual ``ns-3`` code from the repository. The download script is smart enough to know that on some platforms various @@ -189,7 +158,8 @@ pieces of ns-3 are not supported. On your platform you may not see some of these pieces come down. However, on most platforms, the process should continue with something like, -@verbatim +:: + # # Get PyBindGen # @@ -198,14 +168,14 @@ continue with something like, Trying to fetch pybindgen; this will fail if no network connection is available. Hit Ctrl-C to skip. => bzr checkout -rrevno:640 https://launchpad.net/pybindgen pybindgen Fetch was successful. -@end verbatim This was the download script getting the Python bindings generator for you. Note that you will need bazaar (bzr), a version control system, to download PyBindGen. Next you should see (modulo platform variations) something along the lines of, -@verbatim +:: + # # Get NSC # @@ -219,114 +189,106 @@ the lines of, adding file changes added 273 changesets with 17565 changes to 15175 files 10622 files updated, 0 files merged, 0 files removed, 0 files unresolved -@end verbatim This part of the process is the script downloading the Network Simulation Cradle for you. Note that NSC is not supported on OSX or Cygwin and works best with gcc-3.4 or gcc-4.2 or greater series. After the download.py script completes, you should have several new directories -under @code{~/repos/ns-3-allinone}: +under ``~/repos/ns-3-allinone``: + +:: -@verbatim build.py* constants.pyc download.py* nsc/ README util.pyc constants.py dist.py* ns-3-dev/ pybindgen/ util.py -@end verbatim -Go ahead and change into @code{ns-3-dev} under your @code{~/repos/ns-3-allinone} +Go ahead and change into ``ns-3-dev`` under your ``~/repos/ns-3-allinone`` directory. You should see something like the following there: -@verbatim +:: + AUTHORS examples/ RELEASE_NOTES utils/ wscript bindings/ LICENSE samples/ VERSION wutils.py CHANGES.html ns3/ scratch/ waf* doc/ README src/ waf.bat* -@end verbatim -You are now ready to build the @command{ns-3} distribution. +You are now ready to build the |ns3| distribution. -@subsection Downloading ns-3 Using a Tarball -The process for downloading @command{ns-3} via tarball is simpler than the +Downloading ns-3 Using a Tarball +++++++++++++++++++++++++++++++++ +The process for downloading |ns3| via tarball is simpler than the Mercurial process since all of the pieces are pre-packaged for you. You just have to pick a release, download it and decompress it. -As mentioned above, one practice is to create a directory called @code{repos} +As mentioned above, one practice is to create a directory called ``repos`` in one's home directory under which one can keep local Mercurial repositories. -One could also keep a @code{tarballs} directory. @emph{Hint: the tutorial -will assume you downloaded into a @code{repos} directory, so remember the -placekeeper.} If you adopt the @code{tarballs} directory approach, you can +One could also keep a ``tarballs`` directory. *Hint: the tutorial +will assume you downloaded into a ``repos`` directory, so remember the +placekeeper.``* If you adopt the ``tarballs`` directory approach, you can get a copy of a release by typing the following into your Linux shell (substitute the appropriate version numbers, of course): -@verbatim +:: + cd mkdir tarballs cd tarballs - wget http://www.nsnam.org/releases/ns-allinone-3.6.tar.bz2 - tar xjf ns-allinone-3.6.tar.bz2 -@end verbatim + wget http://www.nsnam.org/releases/ns-allinone-3.10.tar.bz2 + tar xjf ns-allinone-3.10.tar.bz2 -If you change into the directory @code{ns-allinone-3.6} you should see a +If you change into the directory ``ns-allinone-3.10`` you should see a number of files: -@verbatim -build.py* ns-3.6/ pybindgen-0.12.0.700/ util.py -constants.py nsc-0.5.1/ README -@end verbatim +:: -You are now ready to build the @command{ns-3} distribution. + build.py ns-3.10/ pybindgen-0.15.0/ util.py + constants.py nsc-0.5.2/ README -@c ======================================================================== -@c Building ns-3 -@c ======================================================================== +You are now ready to build the |ns3| distribution. -@node Building ns-3 -@section Building ns-3 +Building ns-3 +************* -@subsection Building with build.py -@cindex building with build.py -The first time you build the @command{ns-3} project you should build using the -@command{allinone} environment. This will get the project configured for you +Building with build.py +++++++++++++++++++++++ +The first time you build the |ns3| project you should build using the +``allinone`` environment. This will get the project configured for you in the most commonly useful way. Change into the directory you created in the download section above. If you downloaded using Mercurial you should have a directory called -@code{ns-3-allinone} under your @code{~/repos} directory. If you downloaded +``ns-3-allinone`` under your ``~/repos`` directory. If you downloaded using a tarball you should have a directory called something like -@code{ns-allinone-3.6} under your @code{~/tarballs} directory. Take a deep +``ns-allinone-3.10`` under your ``~/tarballs`` directory. Take a deep breath and type the following: -@verbatim +:: + ./build.py -@end verbatim You will see lots of typical compiler output messages displayed as the build script builds the various pieces you downloaded. Eventually you should see the following magic words: -@verbatim +:: + Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' 'build' finished successfully (2m30.586s) -@end verbatim Once the project has built you can say goodbye to your old friends, the -@code{ns-3-allinone} scripts. You got what you needed from them and will now -interact directly with Waf and we do it in the @code{ns-3-dev} directory, -not in the @code{ns-3-allinone} directory. Go ahead and change into the -@code{ns-3-dev} directory (or the directory for the appropriate release you +``ns-3-allinone`` scripts. You got what you needed from them and will now +interact directly with Waf and we do it in the ``ns-3-dev`` directory, +not in the ``ns-3-allinone`` directory. Go ahead and change into the +``ns-3-dev`` directory (or the directory for the appropriate release you downloaded. -@verbatim - cd ns-3-dev -@end verbatim +:: -@subsection Building with Waf -@cindex building with Waf -@cindex configuring Waf -@cindex building debug version with Waf -@cindex compiling with Waf -@cindex unit tests with Waf -We use Waf to configure and build the @command{ns-3} project. It's not + cd ns-3-dev + +Building with Waf ++++++++++++++++++ +We use Waf to configure and build the |ns3| project. It's not strictly required at this point, but it will be valuable to take a slight detour and look at how to make changes to the configuration of the project. Probably the most useful configuration change you can make will be to @@ -335,15 +297,16 @@ your project to build the debug version. Let's tell the project to do make an optimized build. To explain to Waf that it should do optimized builds you will need to execute the following command, -@verbatim +:: + ./waf -d optimized configure -@end verbatim This runs Waf out of the local directory (which is provided as a convenience for you). As the build system checks for various dependencies you should see output that looks similar to the following, -@verbatim +:: + Checking for program g++ : ok /usr/bin/g++ Checking for program cpp : ok /usr/bin/cpp Checking for program ar : ok /usr/bin/ar @@ -401,79 +364,74 @@ output that looks similar to the following, Build examples and samples : enabled Static build : not enabled (option --enable-static not selected) 'configure' finished successfully (2.870s) -@end verbatim Note the last part of the above output. Some ns-3 options are not enabled by default or require support from the underlying system to work properly. For instance, to enable XmlTo, the library libxml-2.0 must be found on the -system. If this library were not found, the corresponding @command{ns-3} feature +system. If this library were not found, the corresponding |ns3| feature would not be enabled and a message would be displayed. Note further that there is -a feature to use the program @code{sudo} to set the suid bit of certain programs. -This is not enabled by default and so this feature is reported as ``not enabled.'' +a feature to use the program ``sudo`` to set the suid bit of certain programs. +This is not enabled by default and so this feature is reported as "not enabled." Now go ahead and switch back to the debug build. -@verbatim +:: + ./waf -d debug configure -@end verbatim The build system is now configured and you can build the debug versions of -the @command{ns-3} programs by simply typing, +the |ns3| programs by simply typing, + +:: -@verbatim ./waf -@end verbatim Some waf commands are meaningful during the build phase and some commands are valid in the configuration phase. For example, if you wanted to use the emulation -features of @command{ns-3} you might want to enable setting the suid bit using +features of |ns3| you might want to enable setting the suid bit using sudo as described above. This turns out to be a configuration-time command, and so you could reconfigure using the following command -@verbatim +:: + ./waf -d debug --enable-sudo configure -@end verbatim If you do this, waf will have run sudo to change the socket creator programs of the emulation code to run as root. There are many other configure- and build-time options available in waf. To explore these options, type: -@verbatim +:: + ./waf --help -@end verbatim We'll use some of the testing-related commands in the next section. -Okay, sorry, I made you build the @command{ns-3} part of the system twice, +Okay, sorry, I made you build the |ns3| part of the system twice, but now you know how to change the configuration and build optimized code. -@c ======================================================================== -@c Testing ns-3 -@c ======================================================================== +Testing ns-3 +************ -@node Testing ns-3 -@section Testing ns-3 +You can run the unit tests of the |ns3| distribution by running the +"./test.py -c core" script, -@cindex unit tests -You can run the unit tests of the @command{ns-3} distribution by running the -``./test.py -c core'' script, +:: -@verbatim ./test.py -c core -@end verbatim These tests are run in parallel by waf. You should eventually see a report saying that, -@verbatim +:: + 47 of 47 tests passed (47 passed, 0 failed, 0 crashed, 0 valgrind errors) -@end verbatim This is the important message. You will also see output from the test runner and the output will actually look something like, -@verbatim +:: + Waf: Entering directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' 'build' finished successfully (1.799s) @@ -494,66 +452,61 @@ You will also see output from the test runner and the output will actually look PASS: TestSuite object PASS: TestSuite random-number-generators 47 of 47 tests passed (47 passed, 0 failed, 0 crashed, 0 valgrind errors) -@end verbatim -This command is typically run by @code{users} to quickly verify that an -@command{ns-3} distribution has built correctly. +This command is typically run by ``users`` to quickly verify that an +|ns3| distribution has built correctly. -@c ======================================================================== -@c Running a Script -@c ======================================================================== - -@node Running a Script -@section Running a Script -@cindex running a script with Waf +Running a Script +**************** We typically run scripts under the control of Waf. This allows the build system to ensure that the shared library paths are set correctly and that the libraries are available at run time. To run a program, simply use the -@code{--run} option in Waf. Let's run the @command{ns-3} equivalent of the +``--run`` option in Waf. Let's run the |ns3| equivalent of the ubiquitous hello world program by typing the following: -@verbatim +:: + ./waf --run hello-simulator -@end verbatim Waf first checks to make sure that the program is built correctly and executes a build if required. Waf then executes the program, which produces the following output. -@verbatim +:: + Hello Simulator -@end verbatim -@emph{Congratulations. You are now an ns-3 user.} +*Congratulations. You are now an ns-3 user.* -@emph{What do I do if I don't see the output?} +*What do I do if I don't see the output?* -If you don't see @code{waf} messages indicating that the build was -completed successfully, but do not see the ``Hello Simulator'' output, -chances are that you have switched your build mode to ``optimized'' in -the ``Building with Waf'' section, but have missed the change back to -``debug'' mode. All of the console output used in this tutorial uses a -special @command{ns-3} logging component that is useful for printing +If you don't see ``waf`` messages indicating that the build was +completed successfully, but do not see the "Hello Simulator" output, +chances are that you have switched your build mode to "optimized" in +the "Building with Waf" section, but have missed the change back to +"debug" mode. All of the console output used in this tutorial uses a +special |ns3| logging component that is useful for printing user messages to the console. Output from this component is automatically disabled when you compile optimized code -- it is -``optimized out.'' If you don't see the ``Hello Simulator'' output, +"optimized out." If you don't see the "Hello Simulator" output, type the following, -@verbatim - ./waf -d debug configure -@end verbatim +:: -to tell @code{waf} to build the debug versions of the @command{ns-3} + ./waf -d debug configure + +to tell ``waf`` to build the debug versions of the |ns3| programs. You must still build the actual debug version of the code by typing, -@verbatim - ./waf -@end verbatim +:: -Now, if you run the @code{hello-simulator} program, you should see the + ./waf + +Now, if you run the ``hello-simulator`` program, you should see the expected output. If you want to run programs under another tool such as gdb or valgrind, -see this @uref{http://www.nsnam.org/wiki/index.php/User_FAQ#How_to_run_NS-3_programs_under_another_tool,,wiki entry}. +see this `wiki entry +`_. diff --git a/doc/tutorial/source/index.rst b/doc/tutorial/source/index.rst new file mode 100644 index 000000000..d0731737a --- /dev/null +++ b/doc/tutorial/source/index.rst @@ -0,0 +1,18 @@ +.. only:: html or latex + + Welcome to ns-3's tutorial! + ================================ + + Contents: + +.. toctree:: + :maxdepth: 2 + + introduction + resources + getting-started + conceptual-overview + tweaking + building-topologies + tracing + conclusion diff --git a/doc/tutorial/source/introduction.rst b/doc/tutorial/source/introduction.rst new file mode 100644 index 000000000..1b489a01a --- /dev/null +++ b/doc/tutorial/source/introduction.rst @@ -0,0 +1,125 @@ +.. include:: replace.txt + +Introduction +------------ + +The |ns3| simulator is a discrete-event network simulator targeted +primarily for research and educational use. The +`ns-3 project +`_, +started in 2006, is an open-source project developing |ns3|. + +Primary documentation for the |ns3| project is available in four +forms: + +* `ns-3 Doxygen/Manual + `_: + Documentation of the public APIs of the simulator +* Tutorial (this document) +* `Reference Manual + `_: Reference Manual +* `ns-3 wiki + `_ + +The purpose of this tutorial is to introduce new |ns3| users to the +system in a structured way. It is sometimes difficult for new users to +glean essential information from detailed manuals and to convert this +information into working simulations. In this tutorial, we will build +several example simulations, introducing and explaining key concepts and +features as we go. + +As the tutorial unfolds, we will introduce the full |ns3| documentation +and provide pointers to source code for those interested in delving deeper +into the workings of the system. + +A few key points are worth noting at the onset: + +* Ns-3 is not an extension of `ns-2 + `_; + it is a new simulator. The two simulators are both written in C++ but + |ns3| is a new simulator that does not support the ns-2 APIs. Some + models from ns-2 have already been ported from ns-2 to |ns3|. The + project will continue to maintain ns-2 while |ns3| is being built, + and will study transition and integration mechanisms. +* |ns3| is open-source, and the project strives to maintain an + open environment for researchers to contribute and share their software. + + +For ns-2 Users +************** + +For those familiar with ns-2, the most visible outward change when moving to +|ns3| is the choice of scripting language. Ns-2 is +scripted in OTcl and results of simulations can be visualized using the +Network Animator nam. It is not possible to run a simulation +in ns-2 purely from C++ (i.e., as a main() program without any OTcl). +Moreover, some components of ns-2 are written in C++ and others in OTcl. +In |ns3|, the simulator is written entirely in C++, with optional +Python bindings. Simulation scripts can therefore be written in C++ +or in Python. The results of some simulations can be visualized by +nam, but new animators are under development. Since |ns3| +generates pcap packet trace files, other utilities can be used to +analyze traces as well. +In this tutorial, we will first concentrate on scripting +directly in C++ and interpreting results via trace files. + +But there are similarities as well (both, for example, are based on C++ +objects, and some code from ns-2 has already been ported to |ns3|). +We will try to highlight differences between ns-2 and |ns3| +as we proceed in this tutorial. + +A question that we often hear is "Should I still use ns-2 or move to +|ns3|?" The answer is that it depends. |ns3| does not have +all of the models that ns-2 currently has, but on the other hand, |ns3| +does have new capabilities (such as handling multiple interfaces on nodes +correctly, use of IP addressing and more alignment with Internet +protocols and designs, more detailed 802.11 models, etc.). ns-2 +models can usually be ported to |ns3| (a porting guide is under +development). There is active development on multiple fronts for +|ns3|. The |ns3| developers believe (and certain early users +have proven) that |ns3| is ready for active use, and should be an +attractive alternative for users looking to start new simulation projects. + +Contributing +************ + +|ns3| is a research and educational simulator, by and for the +research community. It will rely on the ongoing contributions of the +community to develop new models, debug or maintain existing ones, and share +results. There are a few policies that we hope will encourage people to +contribute to |ns3| like they have for ns-2: + +* Open source licensing based on GNU GPLv2 compatibility; +* `wiki + `_; +* `Contributed Code + `_ page, similar to ns-2's popular Contributed Code + `page + `_; +* ``src/contrib`` directory (we will host your contributed code); +* Open `bug tracker + `_; +* |ns3| developers will gladly help potential contributors to get + started with the simulator (please contact `one of us + `_). + +We realize that if you are reading this document, contributing back to +the project is probably not your foremost concern at this point, but +we want you to be aware that contributing is in the spirit of the project and +that even the act of dropping us a note about your early experience +with |ns3| (e.g. "this tutorial section was not clear..."), +reports of stale documentation, etc. are much appreciated. + +Tutorial Organization +********************* + +The tutorial assumes that new users might initially follow a path such as the +following: + +* Try to download and build a copy; +* Try to run a few sample programs; +* Look at simulation output, and try to adjust it. + +As a result, we have tried to organize the tutorial along the above +broad sequences of events. + diff --git a/doc/tutorial/source/replace.txt b/doc/tutorial/source/replace.txt new file mode 100644 index 000000000..4cb2f2303 --- /dev/null +++ b/doc/tutorial/source/replace.txt @@ -0,0 +1,3 @@ +.. |ns3| replace:: *ns-3* + +.. |ns2| replace:: *ns-2* diff --git a/doc/tutorial/source/resources.rst b/doc/tutorial/source/resources.rst new file mode 100644 index 000000000..34e77b776 --- /dev/null +++ b/doc/tutorial/source/resources.rst @@ -0,0 +1,144 @@ +.. include:: replace.txt + +Resources +--------- + +The Web +******* + +There are several important resources of which any |ns3| user must be +aware. The main web site is located at http://www.nsnam.org and +provides access to basic information about the |ns3| system. Detailed +documentation is available through the main web site at +http://www.nsnam.org/documents.html. You can also find documents +relating to the system architecture from this page. + +There is a Wiki that complements the main |ns3| web site which you will +find at http://www.nsnam.org/wiki/. You will find user and developer +FAQs there, as well as troubleshooting guides, third-party contributed code, +papers, etc. + +The source code may be found and browsed at http://code.nsnam.org/. +There you will find the current development tree in the repository named +``ns-3-dev``. Past releases and experimental repositories of the core +developers may also be found there. + +Mercurial +********* + +Complex software systems need some way to manage the organization and +changes to the underlying code and documentation. There are many ways to +perform this feat, and you may have heard of some of the systems that are +currently used to do this. The Concurrent Version System (CVS) is probably +the most well known. + +The |ns3| project uses Mercurial as its source code management system. +Although you do not need to know much about Mercurial in order to complete +this tutorial, we recommend becoming familiar with Mercurial and using it +to access the source code. Mercurial has a web site at +http://www.selenic.com/mercurial/, +from which you can get binary or source releases of this Software +Configuration Management (SCM) system. Selenic (the developer of Mercurial) +also provides a tutorial at +http://www.selenic.com/mercurial/wiki/index.cgi/Tutorial/, +and a QuickStart guide at +http://www.selenic.com/mercurial/wiki/index.cgi/QuickStart/. + +You can also find vital information about using Mercurial and |ns3| +on the main |ns3| web site. + +Waf +*** + +Once you have source code downloaded to your local system, you will need +to compile that source to produce usable programs. Just as in the case of +source code management, there are many tools available to perform this +function. Probably the most well known of these tools is ``make``. Along +with being the most well known, ``make`` is probably the most difficult to +use in a very large and highly configurable system. Because of this, many +alternatives have been developed. Recently these systems have been developed +using the Python language. + +The build system Waf is used on the |ns3| project. It is one +of the new generation of Python-based build systems. You will not need to +understand any Python to build the existing |ns3| system, and will +only have to understand a tiny and intuitively obvious subset of Python in +order to extend the system in most cases. + +For those interested in the gory details of Waf, the main web site can be +found at http://code.google.com/p/waf/. + +Development Environment +*********************** + +As mentioned above, scripting in |ns3| is done in C++ or Python. +As of ns-3.2, most of the |ns3| API is available in Python, but the +models are written in C++ in either case. A working +knowledge of C++ and object-oriented concepts is assumed in this document. +We will take some time to review some of the more advanced concepts or +possibly unfamiliar language features, idioms and design patterns as they +appear. We don't want this tutorial to devolve into a C++ tutorial, though, +so we do expect a basic command of the language. There are an almost +unimaginable number of sources of information on C++ available on the web or +in print. + +If you are new to C++, you may want to find a tutorial- or cookbook-based +book or web site and work through at least the basic features of the language +before proceeding. For instance, `this tutorial +`_. + +The |ns3| system uses several components of the GNU "toolchain" +for development. A +software toolchain is the set of programming tools available in the given +environment. For a quick review of what is included in the GNU toolchain see, +http://en.wikipedia.org/wiki/GNU_toolchain. |ns3| uses gcc, +GNU binutils, and gdb. However, we do not use the GNU build system tools, +neither make nor autotools. We use Waf for these functions. + +Typically an |ns3| author will work in Linux or a Linux-like +environment. For those running under Windows, there do exist environments +which simulate the Linux environment to various degrees. The |ns3| +project supports development in the Cygwin environment for +these users. See http://www.cygwin.com/ +for details on downloading (MinGW is presently not officially supported, +although some of the project maintainers to work with it). Cygwin provides +many of the popular Linux system commands. It can, however, sometimes be +problematic due to the way it actually does its emulation, and sometimes +interactions with other Windows software can cause problems. + +If you do use Cygwin or MinGW; and use Logitech products, we will save you +quite a bit of heartburn right off the bat and encourage you to take a look +at the `MinGW FAQ +`_. + +Search for "Logitech" and read the FAQ entry, "why does make often +crash creating a sh.exe.stackdump file when I try to compile my source code." +Believe it or not, the ``Logitech Process Monitor`` insinuates itself into +every DLL in the system when it is running. It can cause your Cygwin or +MinGW DLLs to die in mysterious ways and often prevents debuggers from +running. Beware of Logitech software when using Cygwin. + +Another alternative to Cygwin is to install a virtual machine environment +such as VMware server and install a Linux virtual machine. + +Socket Programming +****************** + +We will assume a basic facility with the Berkeley Sockets API in the examples +used in this tutorial. If you are new to sockets, we recommend reviewing the +API and some common usage cases. For a good overview of programming TCP/IP +sockets we recommend `TCP/IP Sockets in C, Donahoo and Calvert +`_. + +There is an associated web site that includes source for the examples in the +book, which you can find at: +http://cs.baylor.edu/~donahoo/practical/CSockets/. + +If you understand the first four chapters of the book (or for those who do +not have access to a copy of the book, the echo clients and servers shown in +the website above) you will be in good shape to understand the tutorial. +There is a similar book on Multicast Sockets, +`Multicast Sockets, Makofske and Almeroth +`_. +that covers material you may need to understand if you look at the multicast +examples in the distribution. diff --git a/doc/tutorial/tracing.texi b/doc/tutorial/source/tracing.rst similarity index 61% rename from doc/tutorial/tracing.texi rename to doc/tutorial/source/tracing.rst index 7890f9950..fa1d52400 100644 --- a/doc/tutorial/tracing.texi +++ b/doc/tutorial/source/tracing.rst @@ -1,41 +1,21 @@ -@c ============================================================================ -@c Begin document body here -@c ============================================================================ +.. include:: replace.txt -@c ============================================================================ -@c PART: The Tracing System -@c ============================================================================ -@c The below chapters are under the major heading "The Tracing System" -@c This is similar to the Latex \part command -@c -@c ============================================================================ -@c The Tracing System -@c ============================================================================ -@node The Tracing System -@chapter The Tracing System -@menu -* Background:: -* Overview:: -* A Real Example:: -* Using Mid-Level Trace Helpers:: -@end menu +Tracing +------- -@c ============================================================================ -@c Background -@c ============================================================================ -@node Background -@section Background +Background +********** As mentioned in the Using the Tracing System section, the whole point of running -an @code{ns-3} simulation is to generate output for study. You have two basic -strategies to work with in @code{ns-3}: using generic pre-defined bulk output +an |ns3| simulation is to generate output for study. You have two basic +strategies to work with in |ns3|: using generic pre-defined bulk output mechanisms and parsing their content to extract interesting information; or somehow developing an output mechanism that conveys exactly (and perhaps only) the information wanted. Using pre-defined bulk output mechanisms has the advantage of not requiring any -changes to @code{ns-3}, but it does require programming. Often, pcap or NS_LOG +changes to |ns3|, but it does require programming. Often, pcap or NS_LOG output messages are gathered during simulation runs and separately run through scripts that use grep, sed or awk to parse the messages and reduce and transform the data to a manageable form. Programs must be written to do the @@ -44,10 +24,10 @@ of interest in does not exist in any of the pre-defined output mechanisms, this approach fails. If you need to add some tidbit of information to the pre-defined bulk mechanisms, -this can certainly be done; and if you use one of the @code{ns-3} mechanisms, +this can certainly be done; and if you use one of the |ns3| mechanisms, you may get your code added as a contribution. -@code{ns-3} provides another mechanism, called Tracing, that avoids some of the +|ns3| provides another mechanism, called Tracing, that avoids some of the problems inherent in the bulk output mechanisms. It has several important advantages. First, you can reduce the amount of data you have to manage by only tracing the events of interest to you (for large simulations, dumping everything @@ -57,16 +37,18 @@ postprocessing step with sed or awk script. If you desire, your output can be formatted directly into a form acceptable by gnuplot, for example. You can add hooks in the core which can then be accessed by other users, but which will produce no information unless explicitly asked to do so. For these reasons, we -believe that the @code{ns-3} tracing system is the best way to get information +believe that the |ns3| tracing system is the best way to get information out of a simulation and is also therefore one of the most important mechanisms -to understand in @command{ns-3}. +to understand in |ns3|. -@subsection Blunt Instruments +Blunt Instruments ++++++++++++++++++ There are many ways to get information out of a program. The most straightforward way is to just directly print the information to the standard output, as in, -@verbatim +:: + #include ... void @@ -77,11 +59,10 @@ output, as in, std::cout << "The value of x is " << x << std::endl; ... } -@end verbatim -Nobody is going to prevent you from going deep into the core of @code{ns-3} and +Nobody is going to prevent you from going deep into the core of |ns3| and adding print statements. This is insanely easy to do and, after all, you have -complete control of your own @code{ns-3} branch. This will probably not turn +complete control of your own |ns3| branch. This will probably not turn out to be very satisfactory in the long term, though. As the number of print statements increases in your programs, the task of @@ -89,59 +70,57 @@ dealing with the large number of outputs will become more and more complicated. Eventually, you may feel the need to control what information is being printed in some way; perhaps by turning on and off certain categories of prints, or increasing or decreasing the amount of information you want. If you continue -down this path you may discover that you have re-implemented the @code{NS_LOG} +down this path you may discover that you have re-implemented the ``NS_LOG`` mechanism. In order to avoid that, one of the first things you might consider -is using @code{NS_LOG} itself. +is using ``NS_LOG`` itself. -We mentioned above that one way to get information out of @code{ns-3} is to +We mentioned above that one way to get information out of |ns3| is to parse existing NS_LOG output for interesting information. If you discover that some tidbit of information you need is not present in existing log output, you -could edit the core of @code{ns-3} and simply add your interesting information +could edit the core of |ns3| and simply add your interesting information to the output stream. Now, this is certainly better than adding your own -print statements since it follows @code{ns-3} coding conventions and could +print statements since it follows |ns3| coding conventions and could potentially be useful to other people as a patch to the existing core. Let's pick a random example. If you wanted to add more logging to the -@code{ns-3} TCP socket (@code{tcp-socket-impl.cc}) you could just add a new -message down in the implementation. Notice that in TcpSocketImpl::ProcessAction() -there is no log message for the @code{ACK_TX} case. You could simply add one, +|ns3| TCP socket (``tcp-socket-base.cc``) you could just add a new +message down in the implementation. Notice that in TcpSocketBase::ReceivedAck() +there is no log message for the no ack case. You could simply add one, changing the code from: -@verbatim - bool TcpSocketImpl::ProcessAction (Actions_t a) - { // These actions do not require a packet or any TCP Headers - NS_LOG_FUNCTION (this << a); - switch (a) - { - case NO_ACT: - NS_LOG_LOGIC ("TcpSocketImpl " << this <<" Action: NO_ACT"); - break; - case ACK_TX: - SendEmptyPacket (TcpHeader::ACK); - break; - ... -@end verbatim +:: -to add a new @code{NS_LOG_LOGIC} in the appropriate @code{case} statement: + /** Process the newly received ACK */ + void + TcpSocketBase::ReceivedAck (Ptr packet, const TcpHeader& tcpHeader) + { + NS_LOG_FUNCTION (this << tcpHeader); -@verbatim - bool TcpSocketImpl::ProcessAction (Actions_t a) - { // These actions do not require a packet or any TCP Headers - NS_LOG_FUNCTION (this << a); - switch (a) - { - case NO_ACT: - NS_LOG_LOGIC ("TcpSocketImpl " << this << " Action: NO_ACT"); - break; - case ACK_TX: - NS_LOG_LOGIC ("TcpSocketImpl " << this << " Action: ACK_TX"); - SendEmptyPacket (TcpHeader::ACK); - break; - ... -@end verbatim + // Received ACK. Compare the ACK number against highest unacked seqno + if (0 == (tcpHeader.GetFlags () & TcpHeader::ACK)) + { // Ignore if no ACK flag + } + ... + +to add a new ``NS_LOG_LOGIC`` in the appropriate statement: + +:: + + /** Process the newly received ACK */ + void + TcpSocketBase::ReceivedAck (Ptr packet, const TcpHeader& tcpHeader) + { + NS_LOG_FUNCTION (this << tcpHeader); + + // Received ACK. Compare the ACK number against highest unacked seqno + if (0 == (tcpHeader.GetFlags () & TcpHeader::ACK)) + { // Ignore if no ACK flag + NS_LOG_LOGIC ("TcpSocketBase " << this << " no ACK flag"); + } + ... This may seem fairly simple and satisfying at first glance, but something to -consider is that you will be writing code to add the @code{NS_LOG} statement +consider is that you will be writing code to add the ``NS_LOG`` statement and you will also have to write code (as in grep, sed or awk scripts) to parse the log output in order to isolate your information. This is because even though you have some control over what is output by the logging system, you @@ -154,14 +133,14 @@ through huge amounts of extraneous messages that are of no interest to you. You may be forced to save huge log files to disk and process them down to a few lines whenever you want to do anything. -Since there are no guarantees in @code{ns-3} about the stability of @code{NS_LOG} +Since there are no guarantees in |ns3| about the stability of ``NS_LOG`` output, you may also discover that pieces of log output on which you depend disappear or change between releases. If you depend on the structure of the output, you may find other messages being added or deleted which may affect your parsing code. -For these reasons, we consider prints to @code{std::cout} and NS_LOG messages -to be quick and dirty ways to get more information out of @code{ns-3}. +For these reasons, we consider prints to ``std::cout`` and NS_LOG messages +to be quick and dirty ways to get more information out of |ns3|. It is desirable to have a stable facility using stable APIs that allow one to reach into the core system and only get the information required. It is @@ -170,12 +149,12 @@ core system. Even better would be a system that notified the user when an item of interest changed or an interesting event happened so the user doesn't have to actively poke around in the system looking for things. -The @command{ns-3} tracing system is designed to work along those lines and is +The |ns3| tracing system is designed to work along those lines and is well-integrated with the Attribute and Config subsystems allowing for relatively simple use scenarios. -@node Overview -@section Overview +Overview +******** The ns-3 tracing system is built on the concepts of independent tracing sources and tracing sinks; along with a uniform mechanism for connecting sources to sinks. @@ -206,19 +185,19 @@ getting exactly what they want and only what they want out of the system. Neith of you are impacting any other user by changing what information is output by the system. If you happen to add a trace source, your work as a good open-source citizen may allow other users to provide new utilities that are perhaps very useful -overall, without making any changes to the @code{ns-3} core. +overall, without making any changes to the |ns3| core. -@node A Simple Low-Level Example -@subsection A Simple Low-Level Example +A Simple Low-Level Example +++++++++++++++++++++++++++ Let's take a few minutes and walk through a simple tracing example. We are going to need a little background on Callbacks to understand what is happening in the example, so we have to take a small detour right away. -@node Callbacks -@subsubsection Callbacks +Callbacks +~~~~~~~~~ -The goal of the Callback system in @code{ns-3} is to allow one piece of code to +The goal of the Callback system in |ns3| is to allow one piece of code to call a function (or method in C++) without any specific inter-module dependency. This ultimately means you need some kind of indirection -- you treat the address of the called function as a variable. This variable is called a pointer-to-function @@ -229,55 +208,55 @@ In C the canonical example of a pointer-to-function is a pointer-to-function-returning-integer (PFI). For a PFI taking one int parameter, this could be declared like, -@verbatim - int (*pfi)(int arg) = 0; -@end verbatim +:: -What you get from this is a variable named simply ``pfi'' that is initialized + int (*pfi)(int arg) = 0; + +What you get from this is a variable named simply "pfi" that is initialized to the value 0. If you want to initialize this pointer to something meaningful, you have to have a function with a matching signature. In this case, you could provide a function that looks like, -@verbatim +:: + int MyFunction (int arg) {} -@end verbatim If you have this target, you can initialize the variable to point to your function: -@verbatim +:: + pfi = MyFunction; -@end verbatim You can then call MyFunction indirectly using the more suggestive form of the call, -@verbatim +:: + int result = (*pfi) (1234); -@end verbatim This is suggestive since it looks like you are dereferencing the function pointer just like you would dereference any pointer. Typically, however, people take advantage of the fact that the compiler knows what is going on and will just use a shorter form, -@verbatim - int result = pfi (1234); -@end verbatim +:: -This looks like you are calling a function named ``pfi,'' but the compiler is -smart enough to know to call through the variable @code{pfi} indirectly to -the function @code{MyFunction}. + int result = pfi (1234); + +This looks like you are calling a function named "pfi," but the compiler is +smart enough to know to call through the variable ``pfi`` indirectly to +the function ``MyFunction``. Conceptually, this is almost exactly how the tracing system will work. -Basically, a trace source @emph{is} a callback. When a trace sink expresses +Basically, a trace source *is* a callback. When a trace sink expresses interest in receiving trace events, it adds a Callback to a list of Callbacks internally held by the trace source. When an interesting event happens, the -trace source invokes its @code{operator()} providing zero or more parameters. -The @code{operator()} eventually wanders down into the system and does something +trace source invokes its ``operator()`` providing zero or more parameters. +The ``operator()`` eventually wanders down into the system and does something remarkably like the indirect call you just saw. It provides zero or more -parameters (the call to ``pfi'' above passed one parameter to the target function -@code{MyFunction}. +parameters (the call to "pfi" above passed one parameter to the target function +``MyFunction``. The important difference that the tracing system adds is that for each trace source there is an internal list of Callbacks. Instead of just making one @@ -286,16 +265,17 @@ sink expresses interest in notifications from a trace source, it basically just arranges to add its own function to the callback list. If you are interested in more details about how this is actually arranged in -@code{ns-3}, feel free to peruse the Callback section of the manual. +|ns3|, feel free to peruse the Callback section of the manual. -@node Example Code -@subsubsection Example Code +Example Code +~~~~~~~~~~~~ We have provided some code to implement what is really the simplest example of tracing that can be assembled. You can find this code in the tutorial -directory as @code{fourth.cc}. Let's walk through it. +directory as ``fourth.cc``. Let's walk through it. + +:: -@verbatim /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */ /* * This program is free software; you can redistribute it and/or modify @@ -320,7 +300,6 @@ directory as @code{fourth.cc}. Let's walk through it. #include using namespace ns3; -@end verbatim Most of this code should be quite familiar to you. As mentioned above, the trace system makes heavy use of the Object and Attribute systems, so you will @@ -328,7 +307,7 @@ need to include them. The first two includes above bring in the declarations for those systems explicitly. You could use the core module header, but this illustrates how simple this all really is. -The file, @code{traced-value.h} brings in the required declarations for tracing +The file, ``traced-value.h`` brings in the required declarations for tracing of data that obeys value semantics. In general, value semantics just means that you can pass the object around, not an address. In order to use value semantics at all you have to have an object with an associated copy constructor and @@ -340,11 +319,12 @@ What this all really means is that you will be able to trace changes to a C++ object made using those operators. Since the tracing system is integrated with Attributes, and Attributes work -with Objects, there must be an @command{ns-3} @code{Object} for the trace source +with Objects, there must be an |ns3| ``Object`` for the trace source to live in. The next code snippet declares and defines a simple Object we can work with. -@verbatim +:: + class MyObject : public Object { public: @@ -363,32 +343,32 @@ work with. MyObject () {} TracedValue m_myInt; }; -@end verbatim The two important lines of code, above, with respect to tracing are the -@code{.AddTraceSource} and the @code{TracedValue} declaration of @code{m_myInt}. +``.AddTraceSource`` and the ``TracedValue`` declaration of ``m_myInt``. -The @code{.AddTraceSource} provides the ``hooks'' used for connecting the trace -source to the outside world through the config system. The @code{TracedValue} +The ``.AddTraceSource`` provides the "hooks" used for connecting the trace +source to the outside world through the config system. The ``TracedValue`` declaration provides the infrastructure that overloads the operators mentioned above and drives the callback process. -@verbatim +:: + void IntTrace (int32_t oldValue, int32_t newValue) { std::cout << "Traced " << oldValue << " to " << newValue << std::endl; } -@end verbatim This is the definition of the trace sink. It corresponds directly to a callback function. Once it is connected, this function will be called whenever one of the -overloaded operators of the @code{TracedValue} is executed. +overloaded operators of the ``TracedValue`` is executed. We have now seen the trace source and the trace sink. What remains is code to connect the source to the sink. -@verbatim +:: + int main (int argc, char *argv[]) { @@ -397,27 +377,26 @@ connect the source to the sink. myObject->m_myInt = 1234; } -@end verbatim Here we first create the Object in which the trace source lives. -The next step, the @code{TraceConnectWithoutContext}, forms the connection -between the trace source and the trace sink. Notice the @code{MakeCallback} +The next step, the ``TraceConnectWithoutContext``, forms the connection +between the trace source and the trace sink. Notice the ``MakeCallback`` template function. This function does the magic required to create the -underlying @code{ns-3} Callback object and associate it with the function -@code{IntTrace}. TraceConnect makes the association between your provided -function and the overloaded @code{operator()} in the traced variable referred -to by the ``MyInteger'' Attribute. After this association is made, the trace -source will ``fire'' your provided callback function. +underlying |ns3| Callback object and associate it with the function +``IntTrace``. TraceConnect makes the association between your provided +function and the overloaded ``operator()`` in the traced variable referred +to by the "MyInteger" Attribute. After this association is made, the trace +source will "fire" your provided callback function. The code to make all of this happen is, of course, non-trivial, but the essence -is that you are arranging for something that looks just like the @code{pfi()} +is that you are arranging for something that looks just like the ``pfi()`` example above to be called by the trace source. The declaration of the -@code{TracedValue m_myInt;} in the Object itself performs the magic +``TracedValue m_myInt;`` in the Object itself performs the magic needed to provide the overloaded operators (++, ---, etc.) that will use the -@code{operator()} to actually invoke the Callback with the desired parameters. -The @code{.AddTraceSource} performs the magic to connect the Callback to the -Config system, and @code{TraceConnectWithoutContext} performs the magic to +``operator()`` to actually invoke the Callback with the desired parameters. +The ``.AddTraceSource`` performs the magic to connect the Callback to the +Config system, and ``TraceConnectWithoutContext`` performs the magic to connect your function to the trace source, which is specified by Attribute name. @@ -425,58 +404,60 @@ Let's ignore the bit about context for now. Finally, the line, -@verbatim +:: + myObject->m_myInt = 1234; -@end verbatim -should be interpreted as an invocation of @code{operator=} on the member -variable @code{m_myInt} with the integer @code{1234} passed as a parameter. +should be interpreted as an invocation of ``operator=`` on the member +variable ``m_myInt`` with the integer ``1234`` passed as a parameter. -It turns out that this operator is defined (by @code{TracedValue}) to execute +It turns out that this operator is defined (by ``TracedValue``) to execute a callback that returns void and takes two integer values as parameters --- an old value and a new value for the integer in question. That is exactly -the function signature for the callback function we provided --- @code{IntTrace}. +the function signature for the callback function we provided --- ``IntTrace``. To summarize, a trace source is, in essence, a variable that holds a list of callbacks. A trace sink is a function used as the target of a callback. The Attribute and object type information systems are used to provide a way to -connect trace sources to trace sinks. The act of ``hitting'' a trace source +connect trace sources to trace sinks. The act of "hitting" a trace source is executing an operator on the trace source which fires callbacks. This results in the trace sink callbacks registering interest in the source being called with the parameters provided by the source. If you now build and run this example, -@verbatim - ./waf --run fourth -@end verbatim +:: -you will see the output from the @code{IntTrace} function execute as soon as the + ./waf --run fourth + +you will see the output from the ``IntTrace`` function execute as soon as the trace source is hit: -@verbatim - Traced 0 to 1234 -@end verbatim +:: -When we executed the code, @code{myObject->m_myInt = 1234;}, the trace source + Traced 0 to 1234 + +When we executed the code, ``myObject->m_myInt = 1234;``, the trace source fired and automatically provided the before and after values to the trace sink. -The function @code{IntTrace} then printed this to the standard output. No +The function ``IntTrace`` then printed this to the standard output. No problem. -@subsection Using the Config Subsystem to Connect to Trace Sources +Using the Config Subsystem to Connect to Trace Sources +++++++++++++++++++++++++++++++++++++++++++++++++++++++ -The @code{TraceConnectWithoutContext} call shown above in the simple example is -actually very rarely used in the system. More typically, the @code{Config} +The ``TraceConnectWithoutContext`` call shown above in the simple example is +actually very rarely used in the system. More typically, the ``Config`` subsystem is used to allow selecting a trace source in the system using what is -called a @emph{config path}. We saw an example of this in the previous section -where we hooked the ``CourseChange'' event when we were playing with -@code{third.cc}. +called a *config path*. We saw an example of this in the previous section +where we hooked the "CourseChange" event when we were playing with +``third.cc``. Recall that we defined a trace sink to print course change information from the mobility models of our simulation. It should now be a lot more clear to you what this function is doing. -@verbatim +:: + void CourseChange (std::string context, Ptr model) { @@ -484,244 +465,246 @@ what this function is doing. NS_LOG_UNCOND (context << " x = " << position.x << ", y = " << position.y); } -@end verbatim -When we connected the ``CourseChange'' trace source to the above trace sink, -we used what is called a ``Config Path'' to specify the source when we +When we connected the "CourseChange" trace source to the above trace sink, +we used what is called a "Config Path" to specify the source when we arranged a connection between the pre-defined trace source and the new trace sink: -@verbatim +:: + std::ostringstream oss; oss << "/NodeList/" << wifiStaNodes.Get (nWifi - 1)->GetId () << "/$ns3::MobilityModel/CourseChange"; Config::Connect (oss.str (), MakeCallback (&CourseChange)); -@end verbatim Let's try and make some sense of what is sometimes considered relatively mysterious code. For the purposes of discussion, assume that the node -number returned by the @code{GetId()} is ``7''. In this case, the path +number returned by the ``GetId()`` is "7". In this case, the path above turns out to be, -@verbatim - "/NodeList/7/$ns3::MobilityModel/CourseChange" -@end verbatim +:: -The last segment of a config path must be an @code{Attribute} of an -@code{Object}. In fact, if you had a pointer to the @code{Object} that has the -``CourseChange'' @code{Attribute} handy, you could write this just like we did + "/NodeList/7/$ns3::MobilityModel/CourseChange" + +The last segment of a config path must be an ``Attribute`` of an +``Object``. In fact, if you had a pointer to the ``Object`` that has the +"CourseChange" ``Attribute`` handy, you could write this just like we did in the previous example. You know by now that we typically store pointers to -our nodes in a NodeContainer. In the @code{third.cc} example, the Nodes of -interest are stored in the @code{wifiStaNodes} NodeContainer. In fact, while +our nodes in a NodeContainer. In the ``third.cc`` example, the Nodes of +interest are stored in the ``wifiStaNodes`` NodeContainer. In fact, while putting the path together, we used this container to get a Ptr which we used to call GetId() on. We could have used this Ptr directly to call a connect method directly: -@verbatim +:: + Ptr theObject = wifiStaNodes.Get (nWifi - 1); theObject->TraceConnectWithoutContext ("CourseChange", MakeCallback (&CourseChange)); -@end verbatim -In the @code{third.cc} example, we actually want an additional ``context'' to +In the ``third.cc`` example, we actually want an additional "context" to be delivered along with the Callback parameters (which will be explained below) so we could actually use the following equivalent code, -@verbatim +:: + Ptr theObject = wifiStaNodes.Get (nWifi - 1); theObject->TraceConnect ("CourseChange", MakeCallback (&CourseChange)); -@end verbatim -It turns out that the internal code for @code{Config::ConnectWithoutContext} and -@code{Config::Connect} actually do find a Ptr and call the appropriate +It turns out that the internal code for ``Config::ConnectWithoutContext`` and +``Config::Connect`` actually do find a Ptr and call the appropriate TraceConnect method at the lowest level. -The @code{Config} functions take a path that represents a chain of @code{Object} +The ``Config`` functions take a path that represents a chain of ``Object`` pointers. Each segment of a path corresponds to an Object Attribute. The last segment is the Attribute of interest, and prior segments must be typed to contain -or find Objects. The @code{Config} code parses and ``walks'' this path until it +or find Objects. The ``Config`` code parses and "walks" this path until it gets to the final segment of the path. It then interprets the last segment as -an @code{Attribute} on the last Object it found while walking the path. The -@code{Config} functions then call the appropriate @code{TraceConnect} or -@code{TraceConnectWithoutContext} method on the final Object. Let's see what +an ``Attribute`` on the last Object it found while walking the path. The +``Config`` functions then call the appropriate ``TraceConnect`` or +``TraceConnectWithoutContext`` method on the final Object. Let's see what happens in a bit more detail when the above path is walked. -The leading ``/'' character in the path refers to a so-called namespace. One -of the predefined namespaces in the config system is ``NodeList'' which is a +The leading "/" character in the path refers to a so-called namespace. One +of the predefined namespaces in the config system is "NodeList" which is a list of all of the nodes in the simulation. Items in the list are referred to -by indices into the list, so ``/NodeList/7'' refers to the eighth node in the +by indices into the list, so "/NodeList/7" refers to the eighth node in the list of nodes created during the simulation. This reference is actually a -@code{Ptr} and so is a subclass of an @code{ns3::Object}. +``Ptr`` and so is a subclass of an ``ns3::Object``. -As described in the Object Model section of the @code{ns-3} manual, we support +As described in the Object Model section of the |ns3| manual, we support Object Aggregation. This allows us to form an association between different Objects without any programming. Each Object in an Aggregation can be reached from the other Objects. -The next path segment being walked begins with the ``$'' character. This -indicates to the config system that a @code{GetObject} call should be made +The next path segment being walked begins with the "$" character. This +indicates to the config system that a ``GetObject`` call should be made looking for the type that follows. It turns out that the MobilityHelper used in -@code{third.cc} arranges to Aggregate, or associate, a mobility model to each of -the wireless Nodes. When you add the ``$'' you are asking for another Object that +``third.cc`` arranges to Aggregate, or associate, a mobility model to each of +the wireless Nodes. When you add the "$" you are asking for another Object that has presumably been previously aggregated. You can think of this as switching -pointers from the original Ptr as specified by ``/NodeList/7'' to its -associated mobility model --- which is of type ``$ns3::MobilityModel''. If you -are familiar with @code{GetObject}, we have asked the system to do the following: +pointers from the original Ptr as specified by "/NodeList/7" to its +associated mobility model --- which is of type "$ns3::MobilityModel". If you +are familiar with ``GetObject``, we have asked the system to do the following: + +:: -@verbatim Ptr mobilityModel = node->GetObject () -@end verbatim We are now at the last Object in the path, so we turn our attention to the -Attributes of that Object. The @code{MobilityModel} class defines an Attribute -called ``CourseChange''. You can see this by looking at the source code in -@code{src/mobility/mobility-model.cc} and searching for ``CourseChange'' in your +Attributes of that Object. The ``MobilityModel`` class defines an Attribute +called "CourseChange". You can see this by looking at the source code in +``src/mobility/mobility-model.cc`` and searching for "CourseChange" in your favorite editor. You should find, -@verbatim - .AddTraceSource (``CourseChange'', - ``The value of the position and/or velocity vector changed'', +:: + + .AddTraceSource ("CourseChange", + "The value of the position and/or velocity vector changed", MakeTraceSourceAccessor (&MobilityModel::m_courseChangeTrace)) -@end verbatim which should look very familiar at this point. If you look for the corresponding declaration of the underlying traced variable -in @code{mobility-model.h} you will find +in ``mobility-model.h`` you will find + +:: -@verbatim TracedCallback > m_courseChangeTrace; -@end verbatim -The type declaration @code{TracedCallback} identifies @code{m_courseChangeTrace} +The type declaration ``TracedCallback`` identifies ``m_courseChangeTrace`` as a special list of Callbacks that can be hooked using the Config functions described above. -The @code{MobilityModel} class is designed to be a base class providing a common +The ``MobilityModel`` class is designed to be a base class providing a common interface for all of the specific subclasses. If you search down to the end of -the file, you will see a method defined called @code{NotifyCourseChange()}: +the file, you will see a method defined called ``NotifyCourseChange()``: + +:: -@verbatim void MobilityModel::NotifyCourseChange (void) const { m_courseChangeTrace(this); } -@end verbatim Derived classes will call into this method whenever they do a course change to -support tracing. This method invokes @code{operator()} on the underlying -@code{m_courseChangeTrace}, which will, in turn, invoke all of the registered +support tracing. This method invokes ``operator()`` on the underlying +``m_courseChangeTrace``, which will, in turn, invoke all of the registered Callbacks, calling all of the trace sinks that have registered interest in the trace source by calling a Config function. -So, in the @code{third.cc} example we looked at, whenever a course change is -made in one of the @code{RandomWalk2dMobilityModel} instances installed, there -will be a @code{NotifyCourseChange()} call which calls up into the -@code{MobilityModel} base class. As seen above, this invokes @code{operator()} -on @code{m_courseChangeTrace}, which in turn, calls any registered trace sinks. +So, in the ``third.cc`` example we looked at, whenever a course change is +made in one of the ``RandomWalk2dMobilityModel`` instances installed, there +will be a ``NotifyCourseChange()`` call which calls up into the +``MobilityModel`` base class. As seen above, this invokes ``operator()`` +on ``m_courseChangeTrace``, which in turn, calls any registered trace sinks. In the example, the only code registering an interest was the code that provided -the config path. Therefore, the @code{CourseChange} function that was hooked +the config path. Therefore, the ``CourseChange`` function that was hooked from Node number seven will be the only Callback called. -The final piece of the puzzle is the ``context''. Recall that we saw an output -looking something like the following from @code{third.cc}: +The final piece of the puzzle is the "context". Recall that we saw an output +looking something like the following from ``third.cc``: + +:: -@verbatim /NodeList/7/$ns3::MobilityModel/CourseChange x = 7.27897, y = 2.22677 -@end verbatim The first part of the output is the context. It is simply the path through which the config code located the trace source. In the case we have been looking at there can be any number of trace sources in the system corresponding to any number of nodes with mobility models. There needs to be some way to identify which trace source is actually the one that fired the Callback. An easy way is to request a -trace context when you @code{Config::Connect}. +trace context when you ``Config::Connect``. -@subsection How to Find and Connect Trace Sources, and Discover Callback Signatures +How to Find and Connect Trace Sources, and Discover Callback Signatures ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ The first question that inevitably comes up for new users of the Tracing system is, -``okay, I know that there must be trace sources in the simulation core, but how do -I find out what trace sources are available to me''? +"okay, I know that there must be trace sources in the simulation core, but how do +I find out what trace sources are available to me"? -The second question is, ``okay, I found a trace source, how do I figure out the -config path to use when I connect to it''? +The second question is, "okay, I found a trace source, how do I figure out the +config path to use when I connect to it"? -The third question is, ``okay, I found a trace source, how do I figure out what -the return type and formal arguments of my callback function need to be''? +The third question is, "okay, I found a trace source, how do I figure out what +the return type and formal arguments of my callback function need to be"? -The fourth question is, ``okay, I typed that all in and got this incredibly bizarre -error message, what in the world does it mean''? +The fourth question is, "okay, I typed that all in and got this incredibly bizarre +error message, what in the world does it mean"? -@subsection What Trace Sources are Available? +What Trace Sources are Available? ++++++++++++++++++++++++++++++++++ -The answer to this question is found in the @code{ns-3} Doxygen. Go to the -@code{ns-3} web site @uref{http://www.nsnam.org/getting_started.html,,``here''} -and select the ``Doxygen (stable)'' link ``Documentation'' on the navigation -bar to the left side of the page. Expand the ``Modules'' book in the NS-3 -documentation tree a the upper left by clicking the ``+'' box. Now, expand -the ``Core'' book in the tree by clicking its ``+'' box. You should now +The answer to this question is found in the |ns3| Doxygen. Go to the +|ns3| web site `"here" +`_ +and select the "Doxygen (stable)" link "Documentation" on the navigation +bar to the left side of the page. Expand the "Modules" book in the NS-3 +documentation tree a the upper left by clicking the "+" box. Now, expand +the "Core" book in the tree by clicking its "+" box. You should now see three extremely useful links: -@itemize @bullet -@item The list of all trace sources -@item The list of all attributes -@item The list of all global values -@end itemize +* The list of all trace sources +* The list of all attributes +* The list of all global values -The list of interest to us here is ``the list of all trace sources''. Go +The list of interest to us here is "the list of all trace sources". Go ahead and select that link. You will see, perhaps not too surprisingly, a -list of all of the trace sources available in the @code{ns-3} core. +list of all of the trace sources available in the |ns3| core. -As an example, scroll down to @code{ns3::MobilityModel}. You will find +As an example, scroll down to ``ns3::MobilityModel``. You will find an entry for -@verbatim - CourseChange: The value of the position and/or velocity vector changed -@end verbatim +:: -You should recognize this as the trace source we used in the @code{third.cc} + CourseChange: The value of the position and/or velocity vector changed + +You should recognize this as the trace source we used in the ``third.cc`` example. Perusing this list will be helpful. -@subsection What String do I use to Connect? +What String do I use to Connect? +++++++++++++++++++++++++++++++++ -The easiest way to do this is to grep around in the @code{ns-3} codebase for someone +The easiest way to do this is to grep around in the |ns3| codebase for someone who has already figured it out, You should always try to copy someone else's working code before you start to write your own. Try something like: -@verbatim +:: + find . -name '*.cc' | xargs grep CourseChange | grep Connect -@end verbatim and you may find your answer along with working code. For example, in this -case, @code{./ns-3-dev/examples/wireless/mixed-wireless.cc} has something +case, ``./ns-3-dev/examples/wireless/mixed-wireless.cc`` has something just waiting for you to use: -@verbatim - Config::Connect (``/NodeList/*/$ns3::MobilityModel/CourseChange'', +:: + + Config::Connect ("/NodeList/*/$ns3::MobilityModel/CourseChange", MakeCallback (&CourseChangeCallback)); -@end verbatim If you cannot find any examples in the distribution, you can find this out -from the @code{ns-3} Doxygen. It will probably be simplest just to walk -through the ``CourseChanged'' example. +from the |ns3| Doxygen. It will probably be simplest just to walk +through the "CourseChanged" example. -Let's assume that you have just found the ``CourseChanged'' trace source in -``The list of all trace sources'' and you want to figure out how to connect to -it. You know that you are using (again, from the @code{third.cc} example) an -@code{ns3::RandomWalk2dMobilityModel}. So open the ``Class List'' book in -the NS-3 documentation tree by clicking its ``+'' box. You will now see a -list of all of the classes in @code{ns-3}. Scroll down until you see the -entry for @code{ns3::RandomWalk2dMobilityModel} and follow that link. -You should now be looking at the ``ns3::RandomWalk2dMobilityModel Class -Reference''. +Let's assume that you have just found the "CourseChanged" trace source in +"The list of all trace sources" and you want to figure out how to connect to +it. You know that you are using (again, from the ``third.cc`` example) an +``ns3::RandomWalk2dMobilityModel``. So open the "Class List" book in +the NS-3 documentation tree by clicking its "+" box. You will now see a +list of all of the classes in |ns3|. Scroll down until you see the +entry for ``ns3::RandomWalk2dMobilityModel`` and follow that link. +You should now be looking at the "ns3::RandomWalk2dMobilityModel Class +Reference". -If you now scroll down to the ``Member Function Documentation'' section, you -will see documentation for the @code{GetTypeId} function. You constructed one +If you now scroll down to the "Member Function Documentation" section, you +will see documentation for the ``GetTypeId`` function. You constructed one of these in the simple tracing example above: -@verbatim +:: + static TypeId GetTypeId (void) { static TypeId tid = TypeId ("MyObject") @@ -733,7 +716,6 @@ of these in the simple tracing example above: ; return tid; } -@end verbatim As mentioned above, this is the bit of code that connected the Config and Attribute systems to the underlying trace source. This is also the @@ -743,180 +725,184 @@ connect. You are looking at the same information for the RandomWalk2dMobilityModel; and the information you want is now right there in front of you in the Doxygen: -@verbatim +:: + This object is accessible through the following paths with Config::Set and Config::Connect: /NodeList/[i]/$ns3::MobilityModel/$ns3::RandomWalk2dMobilityModel -@end verbatim -The documentation tells you how to get to the @code{RandomWalk2dMobilityModel} +The documentation tells you how to get to the ``RandomWalk2dMobilityModel`` Object. Compare the string above with the string we actually used in the example code: -@verbatim - "/NodeList/7/$ns3::MobilityModel" -@end verbatim +:: -The difference is due to the fact that two @code{GetObject} calls are implied -in the string found in the documentation. The first, for @code{$ns3::MobilityModel} + "/NodeList/7/$ns3::MobilityModel" + +The difference is due to the fact that two ``GetObject`` calls are implied +in the string found in the documentation. The first, for ``$ns3::MobilityModel`` will query the aggregation for the base class. The second implied -@code{GetObject} call, for @code{$ns3::RandomWalk2dMobilityModel}, is used to ``cast'' +``GetObject`` call, for ``$ns3::RandomWalk2dMobilityModel``, is used to "cast" the base class to the concrete implementation class. The documentation shows both of these operations for you. It turns out that the actual Attribute you are going to be looking for is found in the base class as we have seen. -Look further down in the @code{GetTypeId} doxygen. You will find, +Look further down in the ``GetTypeId`` doxygen. You will find, + +:: -@verbatim No TraceSources defined for this type. TraceSources defined in parent class ns3::MobilityModel: CourseChange: The value of the position and/or velocity vector changed Reimplemented from ns3::MobilityModel -@end verbatim This is exactly what you need to know. The trace source of interest is found in -@code{ns3::MobilityModel} (which you knew anyway). The interesting thing this +``ns3::MobilityModel`` (which you knew anyway). The interesting thing this bit of Doxygen tells you is that you don't need that extra cast in the config path above to get to the concrete class, since the trace source is actually in -the base class. Therefore the additional @code{GetObject} is not required and +the base class. Therefore the additional ``GetObject`` is not required and you simply use the path: -@verbatim +:: + /NodeList/[i]/$ns3::MobilityModel -@end verbatim which perfectly matches the example path: -@verbatim +:: + /NodeList/7/$ns3::MobilityModel -@end verbatim -@subsection What Return Value and Formal Arguments? +What Return Value and Formal Arguments? ++++++++++++++++++++++++++++++++++++++++ -The easiest way to do this is to grep around in the @code{ns-3} codebase for someone +The easiest way to do this is to grep around in the |ns3| codebase for someone who has already figured it out, You should always try to copy someone else's working code. Try something like: -@verbatim +:: + find . -name '*.cc' | xargs grep CourseChange | grep Connect -@end verbatim and you may find your answer along with working code. For example, in this -case, @code{./ns-3-dev/examples/wireless/mixed-wireless.cc} has something +case, ``./ns-3-dev/examples/wireless/mixed-wireless.cc`` has something just waiting for you to use. You will find -@verbatim - Config::Connect (``/NodeList/*/$ns3::MobilityModel/CourseChange'', - MakeCallback (&CourseChangeCallback)); -@end verbatim +:: -as a result of your grep. The @code{MakeCallback} should indicate to you that + Config::Connect ("/NodeList/*/$ns3::MobilityModel/CourseChange", + MakeCallback (&CourseChangeCallback)); + +as a result of your grep. The ``MakeCallback`` should indicate to you that there is a callback function there which you can use. Sure enough, there is: -@verbatim +:: + static void CourseChangeCallback (std::string path, Ptr model) { ... } -@end verbatim -@subsubsection Take my Word for It +Take my Word for It +~~~~~~~~~~~~~~~~~~~ If there are no examples to work from, this can be, well, challenging to actually figure out from the source code. Before embarking on a walkthrough of the code, I'll be kind and just tell you a simple way to figure this out: The return value of your callback will always -be void. The formal parameter list for a @code{TracedCallback} can be found +be void. The formal parameter list for a ``TracedCallback`` can be found from the template parameter list in the declaration. Recall that for our -current example, this is in @code{mobility-model.h}, where we have previously +current example, this is in ``mobility-model.h``, where we have previously found: -@verbatim +:: + TracedCallback > m_courseChangeTrace; -@end verbatim There is a one-to-one correspondence between the template parameter list in the declaration and the formal arguments of the callback function. Here, -there is one template parameter, which is a @code{Ptr}. +there is one template parameter, which is a ``Ptr``. This tells you that you need a function that returns void and takes a -a @code{Ptr}. For example, +a ``Ptr``. For example, + +:: -@verbatim void CourseChangeCallback (Ptr model) { ... } -@end verbatim -That's all you need if you want to @code{Config::ConnectWithoutContext}. If -you want a context, you need to @code{Config::Connect} and use a Callback +That's all you need if you want to ``Config::ConnectWithoutContext``. If +you want a context, you need to ``Config::Connect`` and use a Callback function that takes a string context, then the required argument. -@verbatim +:: + void CourseChangeCallback (std::string path, Ptr model) { ... } -@end verbatim -If you want to ensure that your @code{CourseChangeCallback} is only visible -in your local file, you can add the keyword @code{static} and come up with: +If you want to ensure that your ``CourseChangeCallback`` is only visible +in your local file, you can add the keyword ``static`` and come up with: + +:: -@verbatim static void CourseChangeCallback (std::string path, Ptr model) { ... } -@end verbatim -which is exactly what we used in the @code{third.cc} example. +which is exactly what we used in the ``third.cc`` example. -@subsubsection The Hard Way +The Hard Way +~~~~~~~~~~~~ This section is entirely optional. It is going to be a bumpy ride, especially for those unfamiliar with the details of templates. However, if you get through -this, you will have a very good handle on a lot of the @code{ns-3} low level +this, you will have a very good handle on a lot of the |ns3| low level idioms. So, again, let's figure out what signature of callback function is required for -the ``CourseChange'' Attribute. This is going to be painful, but you only need +the "CourseChange" Attribute. This is going to be painful, but you only need to do this once. After you get through this, you will be able to just look at -a @code{TracedCallback} and understand it. +a ``TracedCallback`` and understand it. The first thing we need to look at is the declaration of the trace source. -Recall that this is in @code{mobility-model.h}, where we have previously +Recall that this is in ``mobility-model.h``, where we have previously found: -@verbatim +:: + TracedCallback > m_courseChangeTrace; -@end verbatim This declaration is for a template. The template parameter is inside the angle-brackets, so we are really interested in finding out what that -@code{TracedCallback<>} is. If you have absolutely no idea where this might +``TracedCallback<>`` is. If you have absolutely no idea where this might be found, grep is your friend. We are probably going to be interested in some kind of declaration in the -@code{ns-3} source, so first change into the @code{src} directory. Then, +|ns3| source, so first change into the ``src`` directory. Then, we know this declaration is going to have to be in some kind of header file, so just grep for it using: -@verbatim +:: + find . -name '*.h' | xargs grep TracedCallback -@end verbatim You'll see 124 lines fly by (I piped this through wc to see how bad it was). Although that may seem like it, that's not really a lot. Just pipe the output through more and start scanning through it. On the first page, you will see some very suspiciously template-looking stuff. -@verbatim +:: + TracedCallback::TracedCallback () TracedCallback::ConnectWithoutContext (c ... TracedCallback::Connect (const CallbackB ... @@ -930,38 +916,38 @@ some very suspiciously template-looking stuff. TracedCallback::operator() (T1 a1, T2 a2 ... TracedCallback::operator() (T1 a1, T2 a2 ... TracedCallback::operator() (T1 a1, T2 a2 ... -@end verbatim It turns out that all of this comes from the header file -@code{traced-callback.h} which sounds very promising. You can then take a -look at @code{mobility-model.h} and see that there is a line which confirms +``traced-callback.h`` which sounds very promising. You can then take a +look at ``mobility-model.h`` and see that there is a line which confirms this hunch: -@verbatim +:: + #include "ns3/traced-callback.h" -@end verbatim Of course, you could have gone at this from the other direction and started -by looking at the includes in @code{mobility-model.h} and noticing the -include of @code{traced-callback.h} and inferring that this must be the file +by looking at the includes in ``mobility-model.h`` and noticing the +include of ``traced-callback.h`` and inferring that this must be the file you want. -In either case, the next step is to take a look at @code{src/core/traced-callback.h} +In either case, the next step is to take a look at ``src/core/traced-callback.h`` in your favorite editor to see what is happening. You will see a comment at the top of the file that should be comforting: -@verbatim +:: + An ns3::TracedCallback has almost exactly the same API as a normal ns3::Callback but instead of forwarding calls to a single function (as an ns3::Callback normally does), it forwards calls to a chain of ns3::Callback. -@end verbatim This should sound very familiar and let you know you are on the right track. Just after this comment, you will find, -@verbatim +:: + template > m_courseChangeTrace; -@end verbatim +:: -The @code{typename T1} in the templated class declaration corresponds to the -@code{Ptr} in the declaration above. All of the other + TracedCallback > m_courseChangeTrace; + +The ``typename T1`` in the templated class declaration corresponds to the +``Ptr`` in the declaration above. All of the other type parameters are left as defaults. Looking at the constructor really doesn't tell you much. The one place where you have seen a connection made -between your Callback function and the tracing system is in the @code{Connect} -and @code{ConnectWithoutContext} functions. If you scroll down, you will see -a @code{ConnectWithoutContext} method here: +between your Callback function and the tracing system is in the ``Connect`` +and ``ConnectWithoutContext`` functions. If you scroll down, you will see +a ``ConnectWithoutContext`` method here: + +:: -@verbatim template}. +the declaration above, the compiler will replace ``T1`` with +``Ptr``. + +:: -@verbatim void TracedCallback::ConnectWithoutContext ... cb { @@ -1013,21 +999,21 @@ the declaration above, the compiler will replace @code{T1} with cb.Assign (callback); m_callbackList.push_back (cb); } -@end verbatim You can now see the implementation of everything we've been talking about. The code creates a Callback of the right type and assigns your function to it. This -is the equivalent of the @code{pfi = MyFunction} we discussed at the start of +is the equivalent of the ``pfi = MyFunction`` we discussed at the start of this section. The code then adds the Callback to the list of Callbacks for this source. The only thing left is to look at the definition of Callback. -Using the same grep trick as we used to find @code{TracedCallback}, you will be -able to find that the file @code{./core/callback.h} is the one we need to look at. +Using the same grep trick as we used to find ``TracedCallback``, you will be +able to find that the file ``./core/callback.h`` is the one we need to look at. If you look down through the file, you will see a lot of probably almost incomprehensible template code. You will eventually come to some Doxygen for the Callback template class, though. Fortunately, there is some English: -@verbatim +:: + This class template implements the Functor Design Pattern. It is used to declare the type of a Callback: - the first non-optional template argument represents @@ -1042,73 +1028,74 @@ the Callback template class, though. Fortunately, there is some English: the type of the fourth argument to the callback. - the sixth optional template argument represents the type of the fifth argument to the callback. -@end verbatim We are trying to figure out what the -@verbatim +:: + Callback > cb; -@end verbatim declaration means. Now we are in a position to understand that the first -(non-optional) parameter, @code{void}, represents the return type of the -Callback. The second (non-optional) parameter, @code{Ptr} +(non-optional) parameter, ``void``, represents the return type of the +Callback. The second (non-optional) parameter, ``Ptr`` represents the first argument to the callback. The Callback in question is your function to receive the trace events. From -this you can infer that you need a function that returns @code{void} and takes -a @code{Ptr}. For example, +this you can infer that you need a function that returns ``void`` and takes +a ``Ptr``. For example, + +:: -@verbatim void CourseChangeCallback (Ptr model) { ... } -@end verbatim -That's all you need if you want to @code{Config::ConnectWithoutContext}. If -you want a context, you need to @code{Config::Connect} and use a Callback -function that takes a string context. This is because the @code{Connect} +That's all you need if you want to ``Config::ConnectWithoutContext``. If +you want a context, you need to ``Config::Connect`` and use a Callback +function that takes a string context. This is because the ``Connect`` function will provide the context for you. You'll need: -@verbatim +:: + void CourseChangeCallback (std::string path, Ptr model) { ... } -@end verbatim -If you want to ensure that your @code{CourseChangeCallback} is only visible -in your local file, you can add the keyword @code{static} and come up with: +If you want to ensure that your ``CourseChangeCallback`` is only visible +in your local file, you can add the keyword ``static`` and come up with: + +:: -@verbatim static void CourseChangeCallback (std::string path, Ptr model) { ... } -@end verbatim -which is exactly what we used in the @code{third.cc} example. Perhaps you +which is exactly what we used in the ``third.cc`` example. Perhaps you should now go back and reread the previous section (Take My Word for It). If you are interested in more details regarding the implementation of -Callbacks, feel free to take a look at the @code{ns-3} manual. They are one -of the most frequently used constructs in the low-level parts of @code{ns-3}. +Callbacks, feel free to take a look at the |ns3| manual. They are one +of the most frequently used constructs in the low-level parts of |ns3|. It is, in my opinion, a quite elegant thing. -@subsection What About TracedValue? +What About TracedValue? ++++++++++++++++++++++++ Earlier in this section, we presented a simple piece of code that used a -@code{TracedValue} to demonstrate the basics of the tracing code. +``TracedValue`` to demonstrate the basics of the tracing code. We just glossed over the way to find the return type and formal arguments -for the @code{TracedValue}. Rather than go through the whole exercise, we -will just point you at the correct file, @code{src/core/traced-value.h} and +for the ``TracedValue``. Rather than go through the whole exercise, we +will just point you at the correct file, ``src/core/traced-value.h`` and to the important piece of code: -@verbatim +:: + template class TracedValue { @@ -1126,212 +1113,215 @@ to the important piece of code: T m_v; TracedCallback m_cb; }; -@end verbatim -Here you see that the @code{TracedValue} is templated, of course. In the simple +Here you see that the ``TracedValue`` is templated, of course. In the simple example case at the start of the section, the typename is int32_t. This means -that the member variable being traced (@code{m_v} in the private section of the -class) will be an @code{int32_t m_v}. The @code{Set} method will take a -@code{const int32_t &v} as a parameter. You should now be able to understand -that the @code{Set} code will fire the @code{m_cb} callback with two parameters: -the first being the current value of the @code{TracedValue}; and the second +that the member variable being traced (``m_v`` in the private section of the +class) will be an ``int32_t m_v``. The ``Set`` method will take a +``const int32_t &v`` as a parameter. You should now be able to understand +that the ``Set`` code will fire the ``m_cb`` callback with two parameters: +the first being the current value of the ``TracedValue``; and the second being the new value being set. -The callback, @code{m_cb} is declared as a @code{TracedCallback} which -will correspond to a @code{TracedCallback} when the class is +The callback, ``m_cb`` is declared as a ``TracedCallback`` which +will correspond to a ``TracedCallback`` when the class is instantiated. -Recall that the callback target of a TracedCallback always returns @code{void}. +Recall that the callback target of a TracedCallback always returns ``void``. Further recall that there is a one-to-one correspondence between the template parameter list in the declaration and the formal arguments of the callback function. Therefore the callback will need to have a function signature that looks like: -@verbatim +:: + void MyCallback (int32_t oldValue, int32_t newValue) { ... } -@end verbatim It probably won't surprise you that this is exactly what we provided in that simple example we covered so long ago: -@verbatim +:: + void IntTrace (int32_t oldValue, int32_t newValue) { std::cout << "Traced " << oldValue << " to " << newValue << std::endl; } -@end verbatim -@c ============================================================================ -@c A Real Example -@c ============================================================================ -@node A Real Example -@section A Real Example +A Real Example +************** Let's do an example taken from one of the best-known books on TCP around. -``TCP/IP Illustrated, Volume 1: The Protocols,'' by W. Richard Stevens is a +"TCP/IP Illustrated, Volume 1: The Protocols," by W. Richard Stevens is a classic. I just flipped the book open and ran across a nice plot of both the congestion window and sequence numbers versus time on page 366. Stevens calls -this, ``Figure 21.10. Value of cwnd and send sequence number while data is being -transmitted.'' Let's just recreate the cwnd part of that plot in @command{ns-3} -using the tracing system and @code{gnuplot}. +this, "Figure 21.10. Value of cwnd and send sequence number while data is being +transmitted." Let's just recreate the cwnd part of that plot in |ns3| +using the tracing system and ``gnuplot``. -@subsection Are There Trace Sources Available? +Are There Trace Sources Available? +++++++++++++++++++++++++++++++++++ The first thing to think about is how we want to get the data out. What is it -that we need to trace? The first thing to do is to consult ``The list of all -trace sources'' to see what we have to work with. Recall that this is found -in the @command{ns-3} Doxygen in the ``Core'' Module section. If you scroll +that we need to trace? The first thing to do is to consult "The list of all +trace sources" to see what we have to work with. Recall that this is found +in the |ns3| Doxygen in the "Core" Module section. If you scroll through the list, you will eventually find: -@verbatim - ns3::TcpSocketImpl +:: + + ns3::TcpNewReno CongestionWindow: The TCP connection's congestion window -@end verbatim -It turns out that the @command{ns-3} TCP implementation lives (mostly) in the -file @code{src/internet-stack/tcp-socket-impl.cc}. If you don't know this a -priori, you can use the recursive grep trick: +It turns out that the |ns3| TCP implementation lives (mostly) in the +file ``src/internet-stack/tcp-socket-base.cc`` while congestion control +variants are in files such as ``src/internet-stack/tcp-newreno.cc``. +If you don't know this a priori, you can use the recursive grep trick: + +:: -@verbatim find . -name '*.cc' | xargs grep -i tcp -@end verbatim You will find page after page of instances of tcp pointing you to that file. -If you open @code{src/internet-stack/tcp-socket-impl.cc} in your favorite +If you open ``src/internet-stack/tcp-newreno.cc`` in your favorite editor, you will see right up at the top of the file, the following declarations: -@verbatim +:: + TypeId - TcpSocketImpl::GetTypeId () + TcpNewReno::GetTypeId () { - static TypeId tid = TypeId(``ns3::TcpSocketImpl'') - .SetParent () - .AddTraceSource (``CongestionWindow'', - ``The TCP connection's congestion window'', - MakeTraceSourceAccessor (&TcpSocketImpl::m_cWnd)) + static TypeId tid = TypeId("ns3::TcpNewReno") + .SetParent () + .AddConstructor () + .AddTraceSource ("CongestionWindow", + "The TCP connection's congestion window", + MakeTraceSourceAccessor (&TcpNewReno::m_cWnd)) ; return tid; } -@end verbatim -This should tell you to look for the declaration of @code{m_cWnd} in the header -file @code{src/internet-stack/tcp-socket-impl.h}. If you open this file in your +This should tell you to look for the declaration of ``m_cWnd`` in the header +file ``src/internet-stack/tcp-newreno.h``. If you open this file in your favorite editor, you will find: -@verbatim +:: + TracedValue m_cWnd; //Congestion window -@end verbatim You should now understand this code completely. If we have a pointer to the -@code{TcpSocketImpl}, we can @code{TraceConnect} to the ``CongestionWindow'' trace +``TcpNewReno``, we can ``TraceConnect`` to the "CongestionWindow" trace source if we provide an appropriate callback target. This is the same kind of trace source that we saw in the simple example at the start of this section, -except that we are talking about @code{uint32_t} instead of @code{int32_t}. +except that we are talking about ``uint32_t`` instead of ``int32_t``. We now know that we need to provide a callback that returns void and takes -two @code{uint32_t} parameters, the first being the old value and the second +two ``uint32_t`` parameters, the first being the old value and the second being the new value: -@verbatim +:: + void CwndTrace (uint32_t oldValue, uint32_t newValue) { ... } -@end verbatim -@subsection What Script to Use? +What Script to Use? ++++++++++++++++++++ It's always best to try and find working code laying around that you can modify, rather than starting from scratch. So the first order of business now -is to find some code that already hooks the ``CongestionWindow'' trace source +is to find some code that already hooks the "CongestionWindow" trace source and see if we can modify it. As usual, grep is your friend: -@verbatim +:: + find . -name '*.cc' | xargs grep CongestionWindow -@end verbatim This will point out a couple of promising candidates: -@code{examples/tcp/tcp-large-transfer.cc} and -@code{src/test/ns3tcp/ns3tcp-cwnd-test-suite.cc}. +``examples/tcp/tcp-large-transfer.cc`` and +``src/test/ns3tcp/ns3tcp-cwnd-test-suite.cc``. We haven't visited any of the test code yet, so let's take a look there. You will typically find that test code is fairly minimal, so this is probably a -very good bet. Open @code{src/test/ns3tcp/ns3tcp-cwnd-test-suite.cc} in your -favorite editor and search for ``CongestionWindow''. You will find, +very good bet. Open ``src/test/ns3tcp/ns3tcp-cwnd-test-suite.cc`` in your +favorite editor and search for "CongestionWindow". You will find, -@verbatim - ns3TcpSocket->TraceConnectWithoutContext (``CongestionWindow'', +:: + + ns3TcpSocket->TraceConnectWithoutContext ("CongestionWindow", MakeCallback (&Ns3TcpCwndTestCase1::CwndChange, this)); -@end verbatim This should look very familiar to you. We mentioned above that if we had a -pointer to the @code{TcpSocketImpl}, we could @code{TraceConnect} to the -``CongestionWindow'' trace source. That's exactly what we have here; so it +pointer to the ``TcpNewReno``, we could ``TraceConnect`` to the +"CongestionWindow" trace source. That's exactly what we have here; so it turns out that this line of code does exactly what we want. Let's go ahead and extract the code we need from this function -(@code{Ns3TcpCwndTestCase1::DoRun (void)}). If you look at this function, -you will find that it looks just like an @code{ns-3} script. It turns out that +(``Ns3TcpCwndTestCase1::DoRun (void)``). If you look at this function, +you will find that it looks just like an |ns3| script. It turns out that is exactly what it is. It is a script run by the test framework, so we can just -pull it out and wrap it in @code{main} instead of in @code{DoRun}. Rather than +pull it out and wrap it in ``main`` instead of in ``DoRun``. Rather than walk through this, step, by step, we have provided the file that results from -porting this test back to a native @code{ns-3} script -- -@code{examples/tutorial/fifth.cc}. +porting this test back to a native |ns3| script -- +``examples/tutorial/fifth.cc``. -@subsection A Common Problem and Solution +A Common Problem and Solution ++++++++++++++++++++++++++++++ -The @code{fifth.cc} example demonstrates an extremely important rule that you -must understand before using any kind of @code{Attribute}: you must ensure -that the target of a @code{Config} command exists before trying to use it. +The ``fifth.cc`` example demonstrates an extremely important rule that you +must understand before using any kind of ``Attribute``: you must ensure +that the target of a ``Config`` command exists before trying to use it. This is no different than saying an object must be instantiated before trying to call it. Although this may seem obvious when stated this way, it does trip up many people trying to use the system for the first time. Let's return to basics for a moment. There are three basic time periods that -exist in any @command{ns-3} script. The first time period is sometimes called -``Configuration Time'' or ``Setup Time,'' and is in force during the period -when the @code{main} function of your script is running, but before -@code{Simulator::Run} is called. The second time period is sometimes called -``Simulation Time'' and is in force during the time period when -@code{Simulator::Run} is actively executing its events. After it completes -executing the simulation, @code{Simulator::Run} will return control back to -the @code{main} function. When this happens, the script enters what can be -called ``Teardown Time,'' which is when the structures and objects created +exist in any |ns3| script. The first time period is sometimes called +"Configuration Time" or "Setup Time," and is in force during the period +when the ``main`` function of your script is running, but before +``Simulator::Run`` is called. The second time period is sometimes called +"Simulation Time" and is in force during the time period when +``Simulator::Run`` is actively executing its events. After it completes +executing the simulation, ``Simulator::Run`` will return control back to +the ``main`` function. When this happens, the script enters what can be +called "Teardown Time," which is when the structures and objects created during setup and taken apart and released. Perhaps the most common mistake made in trying to use the tracing system is assuming that entities constructed dynamically during simulation time are -available during configuration time. In particular, an @command{ns-3} -@code{Socket} is a dynamic object often created by @code{Applications} to -communicate between @code{Nodes}. An @command{ns-3} @code{Application} -always has a ``Start Time'' and a ``Stop Time'' associated with it. In the -vast majority of cases, an @code{Application} will not attempt to create -a dynamic object until its @code{StartApplication} method is called at some -``Start Time''. This is to ensure that the simulation is completely +available during configuration time. In particular, an |ns3| +``Socket`` is a dynamic object often created by ``Applications`` to +communicate between ``Nodes``. An |ns3| ``Application`` +always has a "Start Time" and a "Stop Time" associated with it. In the +vast majority of cases, an ``Application`` will not attempt to create +a dynamic object until its ``StartApplication`` method is called at some +"Start Time". This is to ensure that the simulation is completely configured before the app tries to do anything (what would happen if it tried to connect to a node that didn't exist yet during configuration time). The answer to this issue is to 1) create a simulator event that is run after the dynamic object is created and hook the trace when that event is executed; or 2) create the dynamic object at configuration time, hook it then, and give the object to the system to use during simulation time. We took the second -approach in the @code{fifth.cc} example. This decision required us to create -the @code{MyApp} @code{Application}, the entire purpose of which is to take -a @code{Socket} as a parameter. +approach in the ``fifth.cc`` example. This decision required us to create +the ``MyApp`` ``Application``, the entire purpose of which is to take +a ``Socket`` as a parameter. -@subsection A fifth.cc Walkthrough +A fifth.cc Walkthrough +++++++++++++++++++++++ Now, let's take a look at the example program we constructed by dissecting -the congestion window test. Open @code{examples/tutorial/fifth.cc} in your +the congestion window test. Open ``examples/tutorial/fifth.cc`` in your favorite editor. You should see some familiar looking code: -@verbatim - /* -*- Mode:C++; c-file-style:''gnu''; indent-tabs-mode:nil; -*- */ +:: + + /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */ /* * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as @@ -1357,13 +1347,13 @@ favorite editor. You should see some familiar looking code: using namespace ns3; NS_LOG_COMPONENT_DEFINE ("FifthScriptExample"); -@end verbatim This has all been covered, so we won't rehash it. The next lines of source are the network illustration and a comment addressing the problem described above -with @code{Socket}. +with ``Socket``. + +:: -@verbatim // =========================================================================== // // node 0 node 1 @@ -1398,14 +1388,14 @@ with @code{Socket}. // install in the source node. // =========================================================================== // -@end verbatim This should also be self-explanatory. -The next part is the declaration of the @code{MyApp} @code{Application} that -we put together to allow the @code{Socket} to be created at configuration time. +The next part is the declaration of the ``MyApp`` ``Application`` that +we put together to allow the ``Socket`` to be created at configuration time. + +:: -@verbatim class MyApp : public Application { public: @@ -1432,125 +1422,126 @@ we put together to allow the @code{Socket} to be created at configuration time. bool m_running; uint32_t m_packetsSent; }; -@end verbatim -You can see that this class inherits from the @command{ns-3} @code{Application} -class. Take a look at @code{src/node/application.h} if you are interested in -what is inherited. The @code{MyApp} class is obligated to override the -@code{StartApplication} and @code{StopApplication} methods. These methods are -automatically called when @code{MyApp} is required to start and stop sending +You can see that this class inherits from the |ns3| ``Application`` +class. Take a look at ``src/node/application.h`` if you are interested in +what is inherited. The ``MyApp`` class is obligated to override the +``StartApplication`` and ``StopApplication`` methods. These methods are +automatically called when ``MyApp`` is required to start and stop sending data during the simulation. -@subsubsection How Applications are Started and Stopped (optional) +How Applications are Started and Stopped (optional) +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ It is worthwhile to spend a bit of time explaining how events actually get started in the system. This is another fairly deep explanation, and can be ignored if you aren't planning on venturing down into the guts of the system. It is useful, however, in that the discussion touches on how some very important -parts of @code{ns-3} work and exposes some important idioms. If you are +parts of |ns3| work and exposes some important idioms. If you are planning on implementing new models, you probably want to understand this section. -The most common way to start pumping events is to start an @code{Application}. +The most common way to start pumping events is to start an ``Application``. This is done as the result of the following (hopefully) familar lines of an -@command{ns-3} script: +|ns3| script: + +:: -@verbatim ApplicationContainer apps = ... apps.Start (Seconds (1.0)); apps.Stop (Seconds (10.0)); -@end verbatim -The application container code (see @code{src/helper/application-container.h} if +The application container code (see ``src/helper/application-container.h`` if you are interested) loops through its contained applications and calls, -@verbatim +:: + app->SetStartTime (startTime); -@end verbatim -as a result of the @code{apps.Start} call and +as a result of the ``apps.Start`` call and + +:: -@verbatim app->SetStopTime (stopTime); -@end verbatim -as a result of the @code{apps.Stop} call. +as a result of the ``apps.Stop`` call. The ultimate result of these calls is that we want to have the simulator -automatically make calls into our @code{Applications} to tell them when to -start and stop. In the case of @code{MyApp}, it inherits from class -@code{Application} and overrides @code{StartApplication}, and -@code{StopApplication}. These are the functions that will be called by -the simulator at the appropriate time. In the case of @code{MyApp} you -will find that @code{MyApp::StartApplication} does the initial @code{Bind}, -and @code{Connect} on the socket, and then starts data flowing by calling -@code{MyApp::SendPacket}. @code{MyApp::StopApplication} stops generating +automatically make calls into our ``Applications`` to tell them when to +start and stop. In the case of ``MyApp``, it inherits from class +``Application`` and overrides ``StartApplication``, and +``StopApplication``. These are the functions that will be called by +the simulator at the appropriate time. In the case of ``MyApp`` you +will find that ``MyApp::StartApplication`` does the initial ``Bind``, +and ``Connect`` on the socket, and then starts data flowing by calling +``MyApp::SendPacket``. ``MyApp::StopApplication`` stops generating packets by cancelling any pending send events and closing the socket. -One of the nice things about @command{ns-3} is that you can completely -ignore the implementation details of how your @code{Application} is -``automagically'' called by the simulator at the correct time. But since -we have already ventured deep into @command{ns-3} already, let's go for it. +One of the nice things about |ns3| is that you can completely +ignore the implementation details of how your ``Application`` is +"automagically" called by the simulator at the correct time. But since +we have already ventured deep into |ns3| already, let's go for it. -If you look at @code{src/node/application.cc} you will find that the -@code{SetStartTime} method of an @code{Application} just sets the member -variable @code{m_startTime} and the @code{SetStopTime} method just sets -@code{m_stopTime}. From there, without some hints, the trail will probably +If you look at ``src/node/application.cc`` you will find that the +``SetStartTime`` method of an ``Application`` just sets the member +variable ``m_startTime`` and the ``SetStopTime`` method just sets +``m_stopTime``. From there, without some hints, the trail will probably end. The key to picking up the trail again is to know that there is a global list of all of the nodes in the system. Whenever you create a node in -a simulation, a pointer to that node is added to the global @code{NodeList}. +a simulation, a pointer to that node is added to the global ``NodeList``. -Take a look at @code{src/node/node-list.cc} and search for -@code{NodeList::Add}. The public static implementation calls into a private -implementation called @code{NodeListPriv::Add}. This is a relatively common -idom in @command{ns-3}. So, take a look at @code{NodeListPriv::Add}. There +Take a look at ``src/node/node-list.cc`` and search for +``NodeList::Add``. The public static implementation calls into a private +implementation called ``NodeListPriv::Add``. This is a relatively common +idom in |ns3|. So, take a look at ``NodeListPriv::Add``. There you will find, -@verbatim - Simulator::ScheduleWithContext (index, TimeStep (0), &Node::Start, node); -@end verbatim +:: -This tells you that whenever a @code{Node} is created in a simulation, as -a side-effect, a call to that node's @code{Start} method is scheduled for + Simulator::ScheduleWithContext (index, TimeStep (0), &Node::Start, node); + +This tells you that whenever a ``Node`` is created in a simulation, as +a side-effect, a call to that node's ``Start`` method is scheduled for you that happens at time zero. Don't read too much into that name, yet. It doesn't mean that the node is going to start doing anything, it can be -interpreted as an informational call into the @code{Node} telling it that -the simulation has started, not a call for action telling the @code{Node} +interpreted as an informational call into the ``Node`` telling it that +the simulation has started, not a call for action telling the ``Node`` to start doing something. -So, @code{NodeList::Add} indirectly schedules a call to @code{Node::Start} +So, ``NodeList::Add`` indirectly schedules a call to ``Node::Start`` at time zero to advise a new node that the simulation has started. If you -look in @code{src/node/node.h} you will, however, not find a method called -@code{Node::Start}. It turns out that the @code{Start} method is inherited -from class @code{Object}. All objects in the system can be notified when -the simulation starts, and objects of class @code{Node} are just one kind +look in ``src/node/node.h`` you will, however, not find a method called +``Node::Start``. It turns out that the ``Start`` method is inherited +from class ``Object``. All objects in the system can be notified when +the simulation starts, and objects of class ``Node`` are just one kind of those objects. -Take a look at @code{src/core/object.cc} next and search for @code{Object::Start}. +Take a look at ``src/core/object.cc`` next and search for ``Object::Start``. This code is not as straightforward as you might have expected since -@command{ns-3} @code{Objects} support aggregation. The code in -@code{Object::Start} then loops through all of the objects that have been -aggregated together and calls their @code{DoStart} method. This is another -idiom that is very common in @command{ns-3}. There is a public API method, +|ns3| ``Objects`` support aggregation. The code in +``Object::Start`` then loops through all of the objects that have been +aggregated together and calls their ``DoStart`` method. This is another +idiom that is very common in |ns3|. There is a public API method, that stays constant across implementations, that calls a private implementation method that is inherited and implemented by subclasses. The names are typically -something like @code{MethodName} for the public API and @code{DoMethodName} for +something like ``MethodName`` for the public API and ``DoMethodName`` for the private API. -This tells us that we should look for a @code{Node::DoStart} method in -@code{src/node/node.cc} for the method that will continue our trail. If you +This tells us that we should look for a ``Node::DoStart`` method in +``src/node/node.cc`` for the method that will continue our trail. If you locate the code, you will find a method that loops through all of the devices in the node and then all of the applications in the node calling -@code{device->Start} and @code{application->Start} respectively. +``device->Start`` and ``application->Start`` respectively. -You may already know that classes @code{Device} and @code{Application} both -inherit from class @code{Object} and so the next step will be to look at -what happens when @code{Application::DoStart} is called. Take a look at -@code{src/node/application.cc} and you will find: +You may already know that classes ``Device`` and ``Application`` both +inherit from class ``Object`` and so the next step will be to look at +what happens when ``Application::DoStart`` is called. Take a look at +``src/node/application.cc`` and you will find: + +:: -@verbatim void Application::DoStart (void) { @@ -1561,38 +1552,39 @@ what happens when @code{Application::DoStart} is called. Take a look at } Object::DoStart (); } -@end verbatim Here, we finally come to the end of the trail. If you have kept it all straight, -when you implement an @command{ns-3} @code{Application}, your new application -inherits from class @code{Application}. You override the @code{StartApplication} -and @code{StopApplication} methods and provide mechanisms for starting and -stopping the flow of data out of your new @code{Application}. When a @code{Node} -is created in the simulation, it is added to a global @code{NodeList}. The act -of adding a node to this @code{NodeList} causes a simulator event to be scheduled -for time zero which calls the @code{Node::Start} method of the newly added -@code{Node} to be called when the simulation starts. Since a @code{Node} inherits -from @code{Object}, this calls the @code{Object::Start} method on the @code{Node} -which, in turn, calls the @code{DoStart} methods on all of the @code{Objects} -aggregated to the @code{Node} (think mobility models). Since the @code{Node} -@code{Object} has overridden @code{DoStart}, that method is called when the -simulation starts. The @code{Node::DoStart} method calls the @code{Start} methods -of all of the @code{Applications} on the node. Since @code{Applications} are -also @code{Objects}, this causes @code{Application::DoStart} to be called. When -@code{Application::DoStart} is called, it schedules events for the -@code{StartApplication} and @code{StopApplication} calls on the @code{Application}. +when you implement an |ns3| ``Application``, your new application +inherits from class ``Application``. You override the ``StartApplication`` +and ``StopApplication`` methods and provide mechanisms for starting and +stopping the flow of data out of your new ``Application``. When a ``Node`` +is created in the simulation, it is added to a global ``NodeList``. The act +of adding a node to this ``NodeList`` causes a simulator event to be scheduled +for time zero which calls the ``Node::Start`` method of the newly added +``Node`` to be called when the simulation starts. Since a ``Node`` inherits +from ``Object``, this calls the ``Object::Start`` method on the ``Node`` +which, in turn, calls the ``DoStart`` methods on all of the ``Objects`` +aggregated to the ``Node`` (think mobility models). Since the ``Node`` +``Object`` has overridden ``DoStart``, that method is called when the +simulation starts. The ``Node::DoStart`` method calls the ``Start`` methods +of all of the ``Applications`` on the node. Since ``Applications`` are +also ``Objects``, this causes ``Application::DoStart`` to be called. When +``Application::DoStart`` is called, it schedules events for the +``StartApplication`` and ``StopApplication`` calls on the ``Application``. These calls are designed to start and stop the flow of data from the -@code{Application} +``Application`` This has been another fairly long journey, but it only has to be made once, and -you now understand another very deep piece of @command{ns-3}. +you now understand another very deep piece of |ns3|. -@subsubsection The MyApp Application +The MyApp Application +~~~~~~~~~~~~~~~~~~~~~ -The @code{MyApp} @code{Application} needs a constructor and a destructor, +The ``MyApp`` ``Application`` needs a constructor and a destructor, of course: -@verbatim +:: + MyApp::MyApp () : m_socket (0), m_peer (), @@ -1609,33 +1601,33 @@ of course: { m_socket = 0; } -@end verbatim The existence of the next bit of code is the whole reason why we wrote this -@code{Application} in the first place. +``Application`` in the first place. -@verbatim -void -MyApp::Setup (Ptr socket, Address address, uint32_t packetSize, - uint32_t nPackets, DataRate dataRate) -{ - m_socket = socket; - m_peer = address; - m_packetSize = packetSize; - m_nPackets = nPackets; - m_dataRate = dataRate; -} -@end verbatim +:: + void + MyApp::Setup (Ptr socket, Address address, uint32_t packetSize, + uint32_t nPackets, DataRate dataRate) + { + m_socket = socket; + m_peer = address; + m_packetSize = packetSize; + m_nPackets = nPackets; + m_dataRate = dataRate; + } + This code should be pretty self-explanatory. We are just initializing member variables. The important one from the perspective of tracing is the -@code{Ptr socket} which we needed to provide to the application -during configuration time. Recall that we are going to create the @code{Socket} -as a @code{TcpSocket} (which is implemented by @code{TcpSocketImpl}) and hook -its ``CongestionWindow'' trace source before passing it to the @code{Setup} +``Ptr socket`` which we needed to provide to the application +during configuration time. Recall that we are going to create the ``Socket`` +as a ``TcpSocket`` (which is implemented by ``TcpNewReno``) and hook +its "CongestionWindow" trace source before passing it to the ``Setup`` method. -@verbatim +:: + void MyApp::StartApplication (void) { @@ -1645,23 +1637,23 @@ method. m_socket->Connect (m_peer); SendPacket (); } -@end verbatim -The above code is the overridden implementation @code{Application::StartApplication} -that will be automatically called by the simulator to start our @code{Application} -running at the appropriate time. You can see that it does a @code{Socket} @code{Bind} +The above code is the overridden implementation ``Application::StartApplication`` +that will be automatically called by the simulator to start our ``Application`` +running at the appropriate time. You can see that it does a ``Socket`` ``Bind`` operation. If you are familiar with Berkeley Sockets this shouldn't be a surprise. It performs the required work on the local side of the connection just as you might -expect. The following @code{Connect} will do what is required to establish a connection -with the TCP at @code{Address} m_peer. It should now be clear why we need to defer -a lot of this to simulation time, since the @code{Connect} is going to need a fully -functioning network to complete. After the @code{Connect}, the @code{Application} -then starts creating simulation events by calling @code{SendPacket}. +expect. The following ``Connect`` will do what is required to establish a connection +with the TCP at ``Address`` m_peer. It should now be clear why we need to defer +a lot of this to simulation time, since the ``Connect`` is going to need a fully +functioning network to complete. After the ``Connect``, the ``Application`` +then starts creating simulation events by calling ``SendPacket``. -The next bit of code explains to the @code{Application} how to stop creating +The next bit of code explains to the ``Application`` how to stop creating simulation events. -@verbatim +:: + void MyApp::StopApplication (void) { @@ -1677,25 +1669,25 @@ simulation events. m_socket->Close (); } } -@end verbatim -Every time a simulation event is scheduled, an @code{Event} is created. If the -@code{Event} is pending execution or executing, its method @code{IsRunning} will -return @code{true}. In this code, if @code{IsRunning()} returns true, we -@code{Cancel} the event which removes it from the simulator event queue. By -doing this, we break the chain of events that the @code{Application} is using to -keep sending its @code{Packets} and the @code{Application} goes quiet. After we -quiet the @code{Application} we @code{Close} the socket which tears down the TCP +Every time a simulation event is scheduled, an ``Event`` is created. If the +``Event`` is pending execution or executing, its method ``IsRunning`` will +return ``true``. In this code, if ``IsRunning()`` returns true, we +``Cancel`` the event which removes it from the simulator event queue. By +doing this, we break the chain of events that the ``Application`` is using to +keep sending its ``Packets`` and the ``Application`` goes quiet. After we +quiet the ``Application`` we ``Close`` the socket which tears down the TCP connection. -The socket is actually deleted in the destructor when the @code{m_socket = 0} is +The socket is actually deleted in the destructor when the ``m_socket = 0`` is executed. This removes the last reference to the underlying Ptr which causes the destructor of that Object to be called. -Recall that @code{StartApplication} called @code{SendPacket} to start the -chain of events that describes the @code{Application} behavior. +Recall that ``StartApplication`` called ``SendPacket`` to start the +chain of events that describes the ``Application`` behavior. + +:: -@verbatim void MyApp::SendPacket (void) { @@ -1707,18 +1699,18 @@ chain of events that describes the @code{Application} behavior. ScheduleTx (); } } -@end verbatim -Here, you see that @code{SendPacket} does just that. It creates a @code{Packet} -and then does a @code{Send} which, if you know Berkeley Sockets, is probably +Here, you see that ``SendPacket`` does just that. It creates a ``Packet`` +and then does a ``Send`` which, if you know Berkeley Sockets, is probably just what you expected to see. -It is the responsibility of the @code{Application} to keep scheduling the -chain of events, so the next lines call @code{ScheduleTx} to schedule another -transmit event (a @code{SendPacket}) until the @code{Application} decides it +It is the responsibility of the ``Application`` to keep scheduling the +chain of events, so the next lines call ``ScheduleTx`` to schedule another +transmit event (a ``SendPacket``) until the ``Application`` decides it has sent enough. -@verbatim +:: + void MyApp::ScheduleTx (void) { @@ -1728,31 +1720,31 @@ has sent enough. m_sendEvent = Simulator::Schedule (tNext, &MyApp::SendPacket, this); } } -@end verbatim -Here, you see that @code{ScheduleTx} does exactly that. If the @code{Application} -is running (if @code{StopApplication} has not been called) it will schedule a -new event, which calls @code{SendPacket} again. The alert reader will spot -something that also trips up new users. The data rate of an @code{Application} is -just that. It has nothing to do with the data rate of an underlying @code{Channel}. -This is the rate at which the @code{Application} produces bits. It does not take +Here, you see that ``ScheduleTx`` does exactly that. If the ``Application`` +is running (if ``StopApplication`` has not been called) it will schedule a +new event, which calls ``SendPacket`` again. The alert reader will spot +something that also trips up new users. The data rate of an ``Application`` is +just that. It has nothing to do with the data rate of an underlying ``Channel``. +This is the rate at which the ``Application`` produces bits. It does not take into account any overhead for the various protocols or channels that it uses to -transport the data. If you set the data rate of an @code{Application} to the same -data rate as your underlying @code{Channel} you will eventually get a buffer overflow. +transport the data. If you set the data rate of an ``Application`` to the same +data rate as your underlying ``Channel`` you will eventually get a buffer overflow. -@subsubsection The Trace Sinks +The Trace Sinks +~~~~~~~~~~~~~~~ The whole point of this exercise is to get trace callbacks from TCP indicating the congestion window has been updated. The next piece of code implements the corresponding trace sink: -@verbatim +:: + static void CwndChange (uint32_t oldCwnd, uint32_t newCwnd) { - NS_LOG_UNCOND (Simulator::Now ().GetSeconds () << ``\t'' << newCwnd); + NS_LOG_UNCOND (Simulator::Now ().GetSeconds () << "\t" << newCwnd); } -@end verbatim This should be very familiar to you now, so we won't dwell on the details. This function just logs the current simulation time and the new value of the @@ -1763,30 +1755,32 @@ immediately see a nice graph of the congestion window behavior over time. We added a new trace sink to show where packets are dropped. We are going to add an error model to this code also, so we wanted to demonstrate this working. -@verbatim +:: + static void RxDrop (Ptr p) { NS_LOG_UNCOND ("RxDrop at " << Simulator::Now ().GetSeconds ()); } -@end verbatim -This trace sink will be connected to the ``PhyRxDrop'' trace source of the +This trace sink will be connected to the "PhyRxDrop" trace source of the point-to-point NetDevice. This trace source fires when a packet is dropped -by the physical layer of a @code{NetDevice}. If you take a small detour to the -source (@code{src/devices/point-to-point/point-to-point-net-device.cc}) you will -see that this trace source refers to @code{PointToPointNetDevice::m_phyRxDropTrace}. -If you then look in @code{src/devices/point-to-point/point-to-point-net-device.h} +by the physical layer of a ``NetDevice``. If you take a small detour to the +source (``src/devices/point-to-point/point-to-point-net-device.cc``) you will +see that this trace source refers to ``PointToPointNetDevice::m_phyRxDropTrace``. +If you then look in ``src/devices/point-to-point/point-to-point-net-device.h`` for this member variable, you will find that it is declared as a -@code{TracedCallback >}. This should tell you that the +``TracedCallback >``. This should tell you that the callback target should be a function that returns void and takes a single -parameter which is a @code{Ptr} -- just what we have above. +parameter which is a ``Ptr`` -- just what we have above. -@subsubsection The Main Program +The Main Program +~~~~~~~~~~~~~~~~ The following code should be very familiar to you by now: -@verbatim +:: + int main (int argc, char *argv[]) { @@ -1799,7 +1793,6 @@ The following code should be very familiar to you by now: NetDeviceContainer devices; devices = pointToPoint.Install (nodes); -@end verbatim This creates two nodes with a point-to-point channel between them, just as shown in the illustration at the start of the file. @@ -1810,45 +1803,46 @@ window. To see any interesting behavior, we really want to introduce link errors which will drop packets, cause duplicate ACKs and trigger the more interesting behaviors of the congestion window. -@command{ns-3} provides @code{ErrorModel} objects which can be attached to -@code{Channels}. We are using the @code{RateErrorModel} which allows us -to introduce errors into a @code{Channel} at a given @emph{rate}. +|ns3| provides ``ErrorModel`` objects which can be attached to +``Channels``. We are using the ``RateErrorModel`` which allows us +to introduce errors into a ``Channel`` at a given *rate*. + +:: -@verbatim Ptr em = CreateObjectWithAttributes ( "RanVar", RandomVariableValue (UniformVariable (0., 1.)), "ErrorRate", DoubleValue (0.00001)); devices.Get (1)->SetAttribute ("ReceiveErrorModel", PointerValue (em)); -@end verbatim -The above code instantiates a @code{RateErrorModel} Object. Rather than +The above code instantiates a ``RateErrorModel`` Object. Rather than using the two-step process of instantiating it and then setting Attributes, -we use the convenience function @code{CreateObjectWithAttributes} which -allows us to do both at the same time. We set the ``RanVar'' -@code{Attribute} to a random variable that generates a uniform distribution -from 0 to 1. We also set the ``ErrorRate'' @code{Attribute}. -We then set the resulting instantiated @code{RateErrorModel} as the error -model used by the point-to-point @code{NetDevice}. This will give us some +we use the convenience function ``CreateObjectWithAttributes`` which +allows us to do both at the same time. We set the "RanVar" +``Attribute`` to a random variable that generates a uniform distribution +from 0 to 1. We also set the "ErrorRate" ``Attribute``. +We then set the resulting instantiated ``RateErrorModel`` as the error +model used by the point-to-point ``NetDevice``. This will give us some retransmissions and make our plot a little more interesting. -@verbatim +:: + InternetStackHelper stack; stack.Install (nodes); Ipv4AddressHelper address; - address.SetBase (``10.1.1.0'', ``255.255.255.252''); + address.SetBase ("10.1.1.0", "255.255.255.252"); Ipv4InterfaceContainer interfaces = address.Assign (devices); -@end verbatim The above code should be familiar. It installs internet stacks on our two nodes and creates interfaces and assigns IP addresses for the point-to-point devices. Since we are using TCP, we need something on the destination node to receive -TCP connections and data. The @code{PacketSink} @code{Application} is commonly -used in @command{ns-3} for that purpose. +TCP connections and data. The ``PacketSink`` ``Application`` is commonly +used in |ns3| for that purpose. + +:: -@verbatim uint16_t sinkPort = 8080; Address sinkAddress (InetSocketAddress(interfaces.GetAddress (1), sinkPort)); PacketSinkHelper packetSinkHelper ("ns3::TcpSocketFactory", @@ -1856,109 +1850,110 @@ used in @command{ns-3} for that purpose. ApplicationContainer sinkApps = packetSinkHelper.Install (nodes.Get (1)); sinkApps.Start (Seconds (0.)); sinkApps.Stop (Seconds (20.)); -@end verbatim This should all be familiar, with the exception of, -@verbatim +:: + PacketSinkHelper packetSinkHelper ("ns3::TcpSocketFactory", InetSocketAddress (Ipv4Address::GetAny (), sinkPort)); -@end verbatim -This code instantiates a @code{PacketSinkHelper} and tells it to create sockets -using the class @code{ns3::TcpSocketFactory}. This class implements a design -pattern called ``object factory'' which is a commonly used mechanism for +This code instantiates a ``PacketSinkHelper`` and tells it to create sockets +using the class ``ns3::TcpSocketFactory``. This class implements a design +pattern called "object factory" which is a commonly used mechanism for specifying a class used to create objects in an abstract way. Here, instead of -having to create the objects themselves, you provide the @code{ PacketSinkHelper} -a string that specifies a @code{TypeId} string used to create an object which +having to create the objects themselves, you provide the ``PacketSinkHelper`` +a string that specifies a ``TypeId`` string used to create an object which can then be used, in turn, to create instances of the Objects created by the factory. -The remaining parameter tells the @code{Application} which address and port it -should @code{Bind} to. +The remaining parameter tells the ``Application`` which address and port it +should ``Bind`` to. The next two lines of code will create the socket and connect the trace source. -@verbatim +:: + Ptr ns3TcpSocket = Socket::CreateSocket (nodes.Get (0), TcpSocketFactory::GetTypeId ()); - ns3TcpSocket->TraceConnectWithoutContext (``CongestionWindow'', + ns3TcpSocket->TraceConnectWithoutContext ("CongestionWindow", MakeCallback (&CwndChange)); -@end verbatim -The first statement calls the static member function @code{Socket::CreateSocket} -and provides a @code{Node} and an explicit @code{TypeId} for the object factory +The first statement calls the static member function ``Socket::CreateSocket`` +and provides a ``Node`` and an explicit ``TypeId`` for the object factory used to create the socket. This is a slightly lower level call than the -@code{PacketSinkHelper} call above, and uses an explicit C++ type instead of +``PacketSinkHelper`` call above, and uses an explicit C++ type instead of one referred to by a string. Otherwise, it is conceptually the same thing. -Once the @code{TcpSocket} is created and attached to the @code{Node}, we can -use @code{TraceConnectWithoutContext} to connect the CongestionWindow trace +Once the ``TcpSocket`` is created and attached to the ``Node``, we can +use ``TraceConnectWithoutContext`` to connect the CongestionWindow trace source to our trace sink. -Recall that we coded an @code{Application} so we could take that @code{Socket} +Recall that we coded an ``Application`` so we could take that ``Socket`` we just made (during configuration time) and use it in simulation time. We now -have to instantiate that @code{Application}. We didn't go to any trouble to -create a helper to manage the @code{Application} so we are going to have to -create and install it ``manually''. This is actually quite easy: +have to instantiate that ``Application``. We didn't go to any trouble to +create a helper to manage the ``Application`` so we are going to have to +create and install it "manually". This is actually quite easy: + +:: -@verbatim Ptr app = CreateObject (); app->Setup (ns3TcpSocket, sinkAddress, 1040, 1000, DataRate ("1Mbps")); nodes.Get (0)->AddApplication (app); app->Start (Seconds (1.)); app->Stop (Seconds (20.)); -@end verbatim -The first line creates an @code{Object} of type @code{MyApp} -- our -@code{Application}. The second line tells the @code{Application} what -@code{Socket} to use, what address to connect to, how much data to send +The first line creates an ``Object`` of type ``MyApp`` -- our +``Application``. The second line tells the ``Application`` what +``Socket`` to use, what address to connect to, how much data to send at each send event, how many send events to generate and the rate at which to produce data from those events. -Next, we manually add the @code{MyApp Application} to the source node -and explicitly call the @code{Start} and @code{Stop} methods on the -@code{Application} to tell it when to start and stop doing its thing. +Next, we manually add the ``MyApp Application`` to the source node +and explicitly call the ``Start`` and ``Stop`` methods on the +``Application`` to tell it when to start and stop doing its thing. -We need to actually do the connect from the receiver point-to-point @code{NetDevice} +We need to actually do the connect from the receiver point-to-point ``NetDevice`` to our callback now. -@verbatim +:: + devices.Get (1)->TraceConnectWithoutContext("PhyRxDrop", MakeCallback (&RxDrop)); -@end verbatim It should now be obvious that we are getting a reference to the receiving -@code{Node NetDevice} from its container and connecting the trace source defined -by the attribute ``PhyRxDrop'' on that device to the trace sink @code{RxDrop}. +``Node NetDevice`` from its container and connecting the trace source defined +by the attribute "PhyRxDrop" on that device to the trace sink ``RxDrop``. -Finally, we tell the simulator to override any @code{Applications} and just +Finally, we tell the simulator to override any ``Applications`` and just stop processing events at 20 seconds into the simulation. -@verbatim +:: + Simulator::Stop (Seconds(20)); Simulator::Run (); Simulator::Destroy (); return 0; } -@end verbatim -Recall that as soon as @code{Simulator::Run} is called, configuration time +Recall that as soon as ``Simulator::Run`` is called, configuration time ends, and simulation time begins. All of the work we orchestrated by -creating the @code{Application} and teaching it how to connect and send +creating the ``Application`` and teaching it how to connect and send data actually happens during this function call. -As soon as @code{Simulator::Run} returns, the simulation is complete and -we enter the teardown phase. In this case, @code{Simulator::Destroy} takes +As soon as ``Simulator::Run`` returns, the simulation is complete and +we enter the teardown phase. In this case, ``Simulator::Destroy`` takes care of the gory details and we just return a success code after it completes. -@subsection Running fifth.cc +Running fifth.cc +++++++++++++++++ -Since we have provided the file @code{fifth.cc} for you, if you have built +Since we have provided the file ``fifth.cc`` for you, if you have built your distribution (in debug mode since it uses NS_LOG -- recall that optimized builds optimize out NS_LOGs) it will be waiting for you to run. -@verbatim +:: + ./waf --run fifth Waf: Entering directory `/home/craigdo/repos/ns-3-allinone-dev/ns-3-dev/build Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone-dev/ns-3-dev/build' @@ -1972,71 +1967,72 @@ builds optimize out NS_LOGs) it will be waiting for you to run. 1.2508 9112 RxDrop at 1.25151 ... -@end verbatim You can probably see immediately a downside of using prints of any kind in your traces. We get those extraneous waf messages printed all over our interesting information along with those RxDrop messages. We will remedy that soon, but I'm sure you can't wait to see the results of all of this work. Let's redirect that -output to a file called @code{cwnd.dat}: +output to a file called ``cwnd.dat``: + +:: -@verbatim ./waf --run fifth > cwnd.dat 2>&1 -@end verbatim -Now edit up ``cwnd.dat'' in your favorite editor and remove the waf build status +Now edit up "cwnd.dat" in your favorite editor and remove the waf build status and drop lines, leaving only the traced data (you could also comment out the -@code{TraceConnectWithoutContext("PhyRxDrop", MakeCallback (&RxDrop));} in the +``TraceConnectWithoutContext("PhyRxDrop", MakeCallback (&RxDrop));`` in the script to get rid of the drop prints just as easily. You can now run gnuplot (if you have it installed) and tell it to generate some pretty pictures: -@verbatim +:: + gnuplot> set terminal png size 640,480 gnuplot> set output "cwnd.png" gnuplot> plot "cwnd.dat" using 1:2 title 'Congestion Window' with linespoints gnuplot> exit -@end verbatim You should now have a graph of the congestion window versus time sitting in the -file ``cwnd.png'' in all of its glory, that looks like: +file "cwnd.png" that looks like: -@sp 1 -@center @image{figures/cwnd,,,,png} +.. figure:: figures/cwnd.png -@subsection Using Mid-Level Helpers +Using Mid-Level Helpers ++++++++++++++++++++++++ In the previous section, we showed how to hook a trace source and get hopefully interesting information out of a simulation. Perhaps you will recall that we -called logging to the standard output using @code{std::cout} a ``Blunt Instrument'' +called logging to the standard output using ``std::cout`` a "Blunt Instrument" much earlier in this chapter. We also wrote about how it was a problem having to parse the log output in order to isolate interesting information. It may have occurred to you that we just spent a lot of time implementing an example -that exhibits all of the problems we purport to fix with the @code{ns-3} tracing +that exhibits all of the problems we purport to fix with the |ns3| tracing system! You would be correct. But, bear with us. We're not done yet. One of the most important things we want to do is to is to have the ability to easily control the amount of output coming out of the simulation; and we also want to save those data to a file so we can refer back to it later. We can use -the mid-level trace helpers provided in @code{ns-3} to do just that and complete +the mid-level trace helpers provided in |ns3| to do just that and complete the picture. We provide a script that writes the cwnd change and drop events developed in -the example @code{fifth.cc } to disk in separate files. The cwnd changes are +the example ``fifth.cc`` to disk in separate files. The cwnd changes are stored as a tab-separated ASCII file and the drop events are stored in a pcap file. The changes to make this happen are quite small. -@subsubsection A sixth.cc Walkthrough +A sixth.cc Walkthrough +~~~~~~~~~~~~~~~~~~~~~~ -Let's take a look at the changes required to go from @code{fifth.cc} to -@code{sixth.cc}. Open @code{examples/tutorial/fifth.cc} in your favorite +Let's take a look at the changes required to go from ``fifth.cc`` to +``sixth.cc``. Open ``examples/tutorial/fifth.cc`` in your favorite editor. You can see the first change by searching for CwndChange. You will find that we have changed the signatures for the trace sinks and have added a single line to each sink that writes the traced information to a stream representing a file. -@verbatim +:: + static void CwndChange (Ptr stream, uint32_t oldCwnd, uint32_t newCwnd) { @@ -2050,48 +2046,48 @@ representing a file. NS_LOG_UNCOND ("RxDrop at " << Simulator::Now ().GetSeconds ()); file->Write(Simulator::Now(), p); } -@end verbatim -We have added a ``stream'' parameter to the @code{CwndChange} trace sink. +We have added a "stream" parameter to the ``CwndChange`` trace sink. This is an object that holds (keeps safely alive) a C++ output stream. It turns out that this is a very simple object, but one that manages lifetime issues for the stream and solves a problem that even experienced C++ users run into. It turns out that the copy constructor for ostream is marked private. This means that ostreams do not obey value semantics and cannot be used in any mechanism that requires the stream to be copied. This includes -the @command{ns-3} callback system, which as you may recall, requires objects +the |ns3| callback system, which as you may recall, requires objects that obey value semantics. Further notice that we have added the following -line in the @code{CwndChange} trace sink implementation: +line in the ``CwndChange`` trace sink implementation: + +:: -@verbatim *stream->GetStream () << Simulator::Now ().GetSeconds () << "\t" << oldCwnd << "\t" << newCwnd << std::endl; -@end verbatim -This would be very familiar code if you replaced @code{*stream->GetStream ()} -with @code{std::cout}, as in: +This would be very familiar code if you replaced ``*stream->GetStream ()`` +with ``std::cout``, as in: + +:: -@verbatim std::cout << Simulator::Now ().GetSeconds () << "\t" << oldCwnd << "\t" << newCwnd << std::endl; -@end verbatim -This illustrates that the @code{Ptr} is really just -carrying around a @code{std::ofstream} for you, and you can use it here like +This illustrates that the ``Ptr`` is really just +carrying around a ``std::ofstream`` for you, and you can use it here like any other output stream. -A similar situation happens in @code{RxDrop} except that the object being -passed around (a @code{Ptr}) represents a pcap file. There +A similar situation happens in ``RxDrop`` except that the object being +passed around (a ``Ptr``) represents a pcap file. There is a one-liner in the trace sink to write a timestamp and the contents of the packet being dropped to the pcap file: -@verbatim +:: + file->Write(Simulator::Now(), p); -@end verbatim Of course, if we have objects representing the two files, we need to create them somewhere and also cause them to be passed to the trace sinks. If you -look in the @code{main} function, you will find new code to do just that: +look in the ``main`` function, you will find new code to do just that: + +:: -@verbatim AsciiTraceHelper asciiTraceHelper; Ptr stream = asciiTraceHelper.CreateFileStream ("sixth.cwnd"); ns3TcpSocket->TraceConnectWithoutContext ("CongestionWindow", MakeBoundCallback (&CwndChange, stream)); @@ -2101,7 +2097,6 @@ look in the @code{main} function, you will find new code to do just that: PcapHelper pcapHelper; Ptr file = pcapHelper.CreateFile ("sixth.pcap", std::ios::out, PcapHelper::DLT_PPP); devices.Get (1)->TraceConnectWithoutContext("PhyRxDrop", MakeBoundCallback (&RxDrop, file)); -@end verbatim In the first section of the code snippet above, we are creating the ASCII trace file, creating an object responsible for managing it and using a @@ -2110,134 +2105,135 @@ passed to the sink. Our ASCII trace helpers provide a rich set of functions to make using text (ASCII) files easy. We are just going to illustrate the use of the file stream creation function here. -The @code{CreateFileStream{}} function is basically going to instantiate +The ``CreateFileStream{}`` function is basically going to instantiate a std::ofstream object and create a new file (or truncate an existing file). -This ofstream is packaged up in an @code{ns-3} object for lifetime management +This ofstream is packaged up in an |ns3| object for lifetime management and copy constructor issue resolution. -We then take this @code{ns-3} object representing the file and pass it to -@code{MakeBoundCallback()}. This function creates a callback just like -@code{MakeCallback()}, but it ``binds'' a new value to the callback. This +We then take this |ns3| object representing the file and pass it to +``MakeBoundCallback()``. This function creates a callback just like +``MakeCallback()``, but it "binds" a new value to the callback. This value is added to the callback before it is called. -Essentially, @code{MakeBoundCallback(&CwndChange, stream)} causes the trace -source to add the additional ``stream'' parameter to the front of the formal +Essentially, ``MakeBoundCallback(&CwndChange, stream)`` causes the trace +source to add the additional "stream" parameter to the front of the formal parameter list before invoking the callback. This changes the required -signature of the @code{CwndChange} sink to match the one shown above, which -includes the ``extra'' parameter @code{Ptr stream}. +signature of the ``CwndChange`` sink to match the one shown above, which +includes the "extra" parameter ``Ptr stream``. In the second section of code in the snippet above, we instantiate a -@code{PcapHelper} to do the same thing for our pcap trace file that we did -with the @code{AsciiTraceHelper}. The line of code, +``PcapHelper`` to do the same thing for our pcap trace file that we did +with the ``AsciiTraceHelper``. The line of code, + +:: -@verbatim Ptr file = pcapHelper.CreateFile ("sixth.pcap", "w", PcapHelper::DLT_PPP); -@end verbatim -creates a pcap file named ``sixth.pcap'' with file mode ``w''. This means that +creates a pcap file named "sixth.pcap" with file mode "w". This means that the new file is to truncated if an existing file with that name is found. The -final parameter is the ``data link type'' of the new pcap file. These are -the same as the pcap library data link types defined in @code{bpf.h} if you are -familar with pcap. In this case, @code{DLT_PPP} indicates that the pcap file +final parameter is the "data link type" of the new pcap file. These are +the same as the pcap library data link types defined in ``bpf.h`` if you are +familar with pcap. In this case, ``DLT_PPP`` indicates that the pcap file is going to contain packets prefixed with point to point headers. This is true since the packets are coming from our point-to-point device driver. Other common data link types are DLT_EN10MB (10 MB Ethernet) appropriate for csma devices and DLT_IEEE802_11 (IEEE 802.11) appropriate for wifi devices. These -are defined in @code{src/helper/trace-helper.h"} if you are interested in seeing -the list. The entries in the list match those in @code{bpf.h} but we duplicate +are defined in ``src/helper/trace-helper.h"`` if you are interested in seeing +the list. The entries in the list match those in ``bpf.h`` but we duplicate them to avoid a pcap source dependence. -A @code{ns-3} object representing the pcap file is returned from @code{CreateFile} +A |ns3| object representing the pcap file is returned from ``CreateFile`` and used in a bound callback exactly as it was in the ascii case. An important detour: It is important to notice that even though both of these objects are declared in very similar ways, -@verbatim +:: + Ptr file ... Ptr stream ... -@end verbatim The underlying objects are entirely different. For example, the -Ptr is a smart pointer to an @command{ns-3} Object that is a -fairly heaviweight thing that supports @code{Attributes} and is integrated into +Ptr is a smart pointer to an |ns3| Object that is a +fairly heaviweight thing that supports ``Attributes`` and is integrated into the config system. The Ptr, on the other hand, is a smart pointer to a reference counted object that is a very lightweight thing. Remember to always look at the object you are referencing before making any -assumptions about the ``powers'' that object may have. +assumptions about the "powers" that object may have. -For example, take a look at @code{src/common/pcap-file-object.h} in the +For example, take a look at ``src/common/pcap-file-object.h`` in the distribution and notice, -@verbatim - class PcapFileWrapper : public Object -@end verbatim +:: -that class @code{PcapFileWrapper} is an @command{ns-3} Object by virtue of -its inheritance. Then look at @code{src/common/output-stream-wrapper.h} and + class PcapFileWrapper : public Object + +that class ``PcapFileWrapper`` is an |ns3| Object by virtue of +its inheritance. Then look at ``src/common/output-stream-wrapper.h`` and notice, -@verbatim - class OutputStreamWrapper : public SimpleRefCount -@end verbatim +:: -that this object is not an @command{ns-3} Object at all, it is ``merely'' a + class OutputStreamWrapper : public SimpleRefCount + +that this object is not an |ns3| Object at all, it is "merely" a C++ object that happens to support intrusive reference counting. The point here is that just because you read Ptr it does not necessarily -mean that ``something'' is an @command{ns-3} Object on which you can hang @command{ns-3} -@code{Attributes}, for example. +mean that "something" is an |ns3| Object on which you can hang |ns3| +``Attributes``, for example. Now, back to the example. If you now build and run this example, -@verbatim +:: + ./waf --run sixth -@end verbatim -you will see the same messages appear as when you ran ``fifth'', but two new -files will appear in the top-level directory of your @code{ns-3} distribution. +you will see the same messages appear as when you ran "fifth", but two new +files will appear in the top-level directory of your |ns3| distribution. + +:: -@verbatim sixth.cwnd sixth.pcap -@end verbatim -Since ``sixth.cwnd'' is an ASCII text file, you can view it with @code{cat} +Since "sixth.cwnd" is an ASCII text file, you can view it with ``cat`` or your favorite file viewer. -@verbatim +:: + 1.20919 536 1072 1.21511 1072 1608 ... 9.30922 8893 8925 9.31754 8925 8957 -@end verbatim You have a tab separated file with a timestamp, an old congestion window and a new congestion window suitable for directly importing into your plot program. There are no extraneous prints in the file, no parsing or editing is required. -Since ``sixth.pcap'' is a pcap file, you can fiew it with @code{tcpdump}. +Since "sixth.pcap" is a pcap file, you can fiew it with ``tcpdump``. + +:: -@verbatim reading from file ../../sixth.pcap, link-type PPP (PPP) 1.251507 IP 10.1.1.1.49153 > 10.1.1.2.8080: . 17689:18225(536) ack 1 win 65535 1.411478 IP 10.1.1.1.49153 > 10.1.1.2.8080: . 33808:34312(504) ack 1 win 65535 ... 7.393557 IP 10.1.1.1.49153 > 10.1.1.2.8080: . 781568:782072(504) ack 1 win 65535 8.141483 IP 10.1.1.1.49153 > 10.1.1.2.8080: . 874632:875168(536) ack 1 win 65535 -@end verbatim You have a pcap file with the packets that were dropped in the simulation. There are no other packets present in the file and there is nothing else present to make life difficult. It's been a long journey, but we are now at a point where we can appreciate the -@code{ns-3} tracing system. We have pulled important events out of the middle +|ns3| tracing system. We have pulled important events out of the middle of a TCP implementation and a device driver. We stored those events directly in files usable with commonly known tools. We did this without modifying any of the core code involved, and we did this in only 18 lines of code: -@verbatim +:: + static void CwndChange (Ptr stream, uint32_t oldCwnd, uint32_t newCwnd) { @@ -2265,43 +2261,39 @@ core code involved, and we did this in only 18 lines of code: PcapHelper pcapHelper; Ptr file = pcapHelper.CreateFile ("sixth.pcap", "w", PcapHelper::DLT_PPP); devices.Get (1)->TraceConnectWithoutContext("PhyRxDrop", MakeBoundCallback (&RxDrop, file)); -@end verbatim -@c ============================================================================ -@c Using Trace Helpers -@c ============================================================================ -@node Using Trace Helpers -@section Using Trace Helpers +Using Trace Helpers +******************* -The @code{ns-3} trace helpers provide a rich environment for configuring and +The |ns3| trace helpers provide a rich environment for configuring and selecting different trace events and writing them to files. In previous -sections, primarily ``Building Topologies,'' we have seen several varieties +sections, primarily "Building Topologies," we have seen several varieties of the trace helper methods designed for use inside other (device) helpers. Perhaps you will recall seeing some of these variations: -@verbatim +:: + pointToPoint.EnablePcapAll ("second"); pointToPoint.EnablePcap ("second", p2pNodes.Get (0)->GetId (), 0); csma.EnablePcap ("third", csmaDevices.Get (0), true); pointToPoint.EnableAsciiAll (ascii.CreateFileStream ("myfirst.tr")); -@end verbatim What may not be obvious, though, is that there is a consistent model for all of the trace-related methods found in the system. We will now take a little time -and take a look at the ``big picture''. +and take a look at the "big picture". -There are currently two primary use cases of the tracing helpers in @code{ns-3}: +There are currently two primary use cases of the tracing helpers in |ns3|: Device helpers and protocol helpers. Device helpers look at the problem of specifying which traces should be enabled through a node, device pair. For example, you may want to specify that pcap tracing should be enabled on a -particular device on a specific node. This follows from the @code{ns-3} device +particular device on a specific node. This follows from the |ns3| device conceptual model, and also the conceptual models of the various device helpers. Following naturally from this, the files created follow a -- naming convention. Protocol helpers look at the problem of specifying which traces should be -enabled through a protocol and interface pair. This follows from the @code{ns-3} +enabled through a protocol and interface pair. This follows from the |ns3| protocol stack conceptual model, and also the conceptual models of internet stack helpers. Naturally, the trace files should follow a -- naming convention. @@ -2311,237 +2303,244 @@ There are subtleties that prevent all four classes from behaving identically, but we do strive to make them all work as similarly as possible; and whenever possible there are analogs for all methods in all classes. -@verbatim +:: + | pcap | ascii | -----------------+------+-------| Device Helper | | | -----------------+------+-------| Protocol Helper | | | -----------------+------+-------| -@end verbatim -We use an approach called a @code{mixin} to add tracing functionality to our -helper classes. A @code{mixin} is a class that provides functionality to that +We use an approach called a ``mixin`` to add tracing functionality to our +helper classes. A ``mixin`` is a class that provides functionality to that is inherited by a subclass. Inheriting from a mixin is not considered a form of specialization but is really a way to collect functionality. Let's take a quick look at all four of these cases and their respective -@code{mixins}. +``mixins``. -@subsection Pcap Tracing Device Helpers +Pcap Tracing Device Helpers ++++++++++++++++++++++++++++ The goal of these helpers is to make it easy to add a consistent pcap trace -facility to an @code{ns-3} device. We want all of the various flavors of +facility to an |ns3| device. We want all of the various flavors of pcap tracing to work the same across all devices, so the methods of these helpers are inherited by device helpers. Take a look at -@code{src/helper/trace-helper.h} if you want to follow the discussion while +``src/helper/trace-helper.h`` if you want to follow the discussion while looking at real code. -The class @code{PcapHelperForDevice} is a @code{mixin} provides the high level -functionality for using pcap tracing in an @code{ns-3} device. Every device +The class ``PcapHelperForDevice`` is a ``mixin`` provides the high level +functionality for using pcap tracing in an |ns3| device. Every device must implement a single virtual method inherited from this class. -@verbatim +:: + virtual void EnablePcapInternal (std::string prefix, Ptr nd, bool promiscuous, bool explicitFilename) = 0; -@end verbatim The signature of this method reflects the device-centric view of the situation at this level. All of the public methods inherited from class -2@code{PcapUserHelperForDevice} reduce to calling this single device-dependent +2``PcapUserHelperForDevice`` reduce to calling this single device-dependent implementation method. For example, the lowest level pcap method, -@verbatim - void EnablePcap (std::string prefix, Ptr nd, bool promiscuous = false, bool explicitFilename = false); -@end verbatim +:: -will call the device implementation of @code{EnablePcapInternal} directly. All + void EnablePcap (std::string prefix, Ptr nd, bool promiscuous = false, bool explicitFilename = false); + +will call the device implementation of ``EnablePcapInternal`` directly. All other public pcap tracing methods build on this implementation to provide additional user-level functionality. What this means to the user is that all device helpers in the system will have all of the pcap trace methods available; and these methods will all work in the same way across devices if the device -implements @code{EnablePcapInternal} correctly. +implements ``EnablePcapInternal`` correctly. -@subsubsection Pcap Tracing Device Helper Methods +Pcap Tracing Device Helper Methods +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +:: -@verbatim void EnablePcap (std::string prefix, Ptr nd, bool promiscuous = false, bool explicitFilename = false); void EnablePcap (std::string prefix, std::string ndName, bool promiscuous = false, bool explicitFilename = false); void EnablePcap (std::string prefix, NetDeviceContainer d, bool promiscuous = false); void EnablePcap (std::string prefix, NodeContainer n, bool promiscuous = false); void EnablePcap (std::string prefix, uint32_t nodeid, uint32_t deviceid, bool promiscuous = false); void EnablePcapAll (std::string prefix, bool promiscuous = false); -@end verbatim In each of the methods shown above, there is a default parameter called -@code{promiscuous} that defaults to false. This parameter indicates that the +``promiscuous`` that defaults to false. This parameter indicates that the trace should not be gathered in promiscuous mode. If you do want your traces to include all traffic seen by the device (and if the device supports a promiscuous mode) simply add a true parameter to any of the calls above. For example, -@verbatim +:: + Ptr nd; ... helper.EnablePcap ("prefix", nd, true); -@end verbatim -will enable promiscuous mode captures on the @code{NetDevice} specified by @code{nd}. +will enable promiscuous mode captures on the ``NetDevice`` specified by ``nd``. -The first two methods also include a default parameter called @code{explicitFilename} +The first two methods also include a default parameter called ``explicitFilename`` that will be discussed below. -You are encouraged to peruse the Doxygen for class @code{PcapHelperForDevice} +You are encouraged to peruse the Doxygen for class ``PcapHelperForDevice`` to find the details of these methods; but to summarize ... You can enable pcap tracing on a particular node/net-device pair by providing a -@code{Ptr} to an @code{EnablePcap} method. The @code{Ptr} is -implicit since the net device must belong to exactly one @code{Node}. +``Ptr`` to an ``EnablePcap`` method. The ``Ptr`` is +implicit since the net device must belong to exactly one ``Node``. For example, -@verbatim +:: + Ptr nd; ... helper.EnablePcap ("prefix", nd); -@end verbatim You can enable pcap tracing on a particular node/net-device pair by providing a -@code{std::string} representing an object name service string to an -@code{EnablePcap} method. The @code{Ptr} is looked up from the name -string. Again, the @code is implicit since the named net device must -belong to exactly one @code{Node}. For example, +``std::string`` representing an object name service string to an +``EnablePcap`` method. The ``Ptr`` is looked up from the name +string. Again, the ```` is implicit since the named net device must +belong to exactly one ``Node``. For example, + +:: -@verbatim Names::Add ("server" ...); Names::Add ("server/eth0" ...); ... helper.EnablePcap ("prefix", "server/ath0"); -@end verbatim You can enable pcap tracing on a collection of node/net-device pairs by -providing a @code{NetDeviceContainer}. For each @code{NetDevice} in the container +providing a ``NetDeviceContainer``. For each ``NetDevice`` in the container the type is checked. For each device of the proper type (the same type as is -managed by the device helper), tracing is enabled. Again, the @code is -implicit since the found net device must belong to exactly one @code{Node}. +managed by the device helper), tracing is enabled. Again, the ```` is +implicit since the found net device must belong to exactly one ``Node``. For example, -@verbatim +:: + NetDeviceContainer d = ...; ... helper.EnablePcap ("prefix", d); -@end verbatim You can enable pcap tracing on a collection of node/net-device pairs by -providing a @code{NodeContainer}. For each @code{Node} in the @code{NodeContainer} -its attached @code{NetDevices} are iterated. For each @code{NetDevice} attached +providing a ``NodeContainer``. For each ``Node`` in the ``NodeContainer`` +its attached ``NetDevices`` are iterated. For each ``NetDevice`` attached to each node in the container, the type of that device is checked. For each device of the proper type (the same type as is managed by the device helper), tracing is enabled. -@verbatim +:: + NodeContainer n; ... helper.EnablePcap ("prefix", n); -@end verbatim You can enable pcap tracing on the basis of node ID and device ID as well as -with explicit @code{Ptr}. Each @code{Node} in the system has an integer node ID +with explicit ``Ptr``. Each ``Node`` in the system has an integer node ID and each device connected to a node has an integer device ID. -@verbatim +:: + helper.EnablePcap ("prefix", 21, 1); -@end verbatim Finally, you can enable pcap tracing for all devices in the system, with the same type as that managed by the device helper. -@verbatim - helper.EnablePcapAll ("prefix"); -@end verbatim +:: -@subsubsection Pcap Tracing Device Helper Filename Selection + helper.EnablePcapAll ("prefix"); + +Pcap Tracing Device Helper Filename Selection +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Implicit in the method descriptions above is the construction of a complete filename by the implementation method. By convention, pcap traces in the -@code{ns-3} system are of the form ``--.pcap'' +|ns3| system are of the form "--.pcap" As previously mentioned, every node in the system will have a system-assigned node id; and every device will have an interface index (also called a device id) relative to its node. By default, then, a pcap trace file created as a result -of enabling tracing on the first device of node 21 using the prefix ``prefix'' -would be ``prefix-21-1.pcap''. +of enabling tracing on the first device of node 21 using the prefix "prefix" +would be "prefix-21-1.pcap". -You can always use the @code{ns-3} object name service to make this more clear. -For example, if you use the object name service to assign the name ``server'' +You can always use the |ns3| object name service to make this more clear. +For example, if you use the object name service to assign the name "server" to node 21, the resulting pcap trace file name will automatically become, -``prefix-server-1.pcap'' and if you also assign the name ``eth0'' to the +"prefix-server-1.pcap" and if you also assign the name "eth0" to the device, your pcap file name will automatically pick this up and be called -``prefix-server-eth0.pcap''. +"prefix-server-eth0.pcap". Finally, two of the methods shown above, -@verbatim +:: + void EnablePcap (std::string prefix, Ptr nd, bool promiscuous = false, bool explicitFilename = false); void EnablePcap (std::string prefix, std::string ndName, bool promiscuous = false, bool explicitFilename = false); -@end verbatim -have a default parameter called @code{explicitFilename}. When set to true, +have a default parameter called ``explicitFilename``. When set to true, this parameter disables the automatic filename completion mechanism and allows you to create an explicit filename. This option is only available in the methods which enable pcap tracing on a single device. For example, in order to arrange for a device helper to create a single -promiscuous pcap capture file of a specific name (``my-pcap-file.pcap'') on a +promiscuous pcap capture file of a specific name ("my-pcap-file.pcap") on a given device, one could: -@verbatim +:: + Ptr nd; ... helper.EnablePcap ("my-pcap-file.pcap", nd, true, true); -@end verbatim -The first @code{true} parameter enables promiscuous mode traces and the second -tells the helper to interpret the @code{prefix} parameter as a complete filename. +The first ``true`` parameter enables promiscuous mode traces and the second +tells the helper to interpret the ``prefix`` parameter as a complete filename. -@subsection Ascii Tracing Device Helpers +Ascii Tracing Device Helpers +++++++++++++++++++++++++++++ -The behavior of the ascii trace helper @code{mixin} is substantially similar to -the pcap version. Take a look at @code{src/helper/trace-helper.h} if you want to +The behavior of the ascii trace helper ``mixin`` is substantially similar to +the pcap version. Take a look at ``src/helper/trace-helper.h`` if you want to follow the discussion while looking at real code. -The class @code{AsciiTraceHelperForDevice} adds the high level functionality for +The class ``AsciiTraceHelperForDevice`` adds the high level functionality for using ascii tracing to a device helper class. As in the pcap case, every device -must implement a single virtual method inherited from the ascii trace @code{mixin}. +must implement a single virtual method inherited from the ascii trace ``mixin``. + +:: -@verbatim virtual void EnableAsciiInternal (Ptr stream, std::string prefix, Ptr nd, bool explicitFilename) = 0; -@end verbatim The signature of this method reflects the device-centric view of the situation at this level; and also the fact that the helper may be writing to a shared output stream. All of the public ascii-trace-related methods inherited from -class @code{AsciiTraceHelperForDevice} reduce to calling this single device- +class ``AsciiTraceHelperForDevice`` reduce to calling this single device- dependent implementation method. For example, the lowest level ascii trace methods, -@verbatim +:: + void EnableAscii (std::string prefix, Ptr nd, bool explicitFilename = false); void EnableAscii (Ptr stream, Ptr nd); -@verbatim -will call the device implementation of @code{EnableAsciiInternal} directly, + +will call the device implementation of ``EnableAsciiInternal`` directly, providing either a valid prefix or stream. All other public ascii tracing methods will build on these low-level functions to provide additional user-level functionality. What this means to the user is that all device helpers in the system will have all of the ascii trace methods available; and these methods will all work in the same way across devices if the devices implement -@code{EnablAsciiInternal} correctly. +``EnablAsciiInternal`` correctly. -@subsubsection Ascii Tracing Device Helper Methods +Ascii Tracing Device Helper Methods +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +:: -@verbatim void EnableAscii (std::string prefix, Ptr nd, bool explicitFilename = false); void EnableAscii (Ptr stream, Ptr nd); @@ -2559,9 +2558,8 @@ will all work in the same way across devices if the devices implement void EnableAscii (std::string prefix, uint32_t nodeid, uint32_t deviceid, bool explicitFilename); void EnableAscii (Ptr stream, uint32_t nodeid, uint32_t deviceid); -@end verbatim -You are encouraged to peruse the Doxygen for class @code{TraceHelperForDevice} +You are encouraged to peruse the Doxygen for class ``TraceHelperForDevice`` to find the details of these methods; but to summarize ... There are twice as many methods available for ascii tracing as there were for @@ -2573,30 +2571,31 @@ replaced by a mechanism to refer to a common file; and the number of API methods is doubled to allow all combinations. Just as in pcap tracing, you can enable ascii tracing on a particular -node/net-device pair by providing a @code{Ptr} to an @code{EnableAscii} -method. The @code{Ptr} is implicit since the net device must belong to -exactly one @code{Node}. For example, +node/net-device pair by providing a ``Ptr`` to an ``EnableAscii`` +method. The ``Ptr`` is implicit since the net device must belong to +exactly one ``Node``. For example, + +:: -@verbatim Ptr nd; ... helper.EnableAscii ("prefix", nd); -@end verbatim -The first four methods also include a default parameter called @code{explicitFilename} +The first four methods also include a default parameter called ``explicitFilename`` that operate similar to equivalent parameters in the pcap case. In this case, no trace contexts are written to the ascii trace file since they would be redundant. The system will pick the file name to be created using the same rules as described in the pcap section, except that the file will -have the suffix ``.tr'' instead of ``.pcap''. +have the suffix ".tr" instead of ".pcap". If you want to enable ascii tracing on more than one net device and have all traces sent to a single file, you can do that as well by using an object to -refer to a single file. We have already seen this in the ``cwnd'' example +refer to a single file. We have already seen this in the "cwnd" example above: -@verbatim +:: + Ptr nd1; Ptr nd2; ... @@ -2604,20 +2603,21 @@ above: ... helper.EnableAscii (stream, nd1); helper.EnableAscii (stream, nd2); -@verbatim + In this case, trace contexts are written to the ascii trace file since they are required to disambiguate traces from the two devices. Note that since the -user is completely specifying the file name, the string should include the ``,tr'' +user is completely specifying the file name, the string should include the ",tr" for consistency. You can enable ascii tracing on a particular node/net-device pair by providing a -@code{std::string} representing an object name service string to an -@code{EnablePcap} method. The @code{Ptr} is looked up from the name -string. Again, the @code is implicit since the named net device must -belong to exactly one @code{Node}. For example, +``std::string`` representing an object name service string to an +``EnablePcap`` method. The ``Ptr`` is looked up from the name +string. Again, the ```` is implicit since the named net device must +belong to exactly one ``Node``. For example, + +:: -@verbatim Names::Add ("client" ...); Names::Add ("client/eth0" ...); Names::Add ("server" ...); @@ -2625,14 +2625,14 @@ belong to exactly one @code{Node}. For example, ... helper.EnableAscii ("prefix", "client/eth0"); helper.EnableAscii ("prefix", "server/eth0"); -@end verbatim -This would result in two files named ``prefix-client-eth0.tr'' and -``prefix-server-eth0.tr'' with traces for each device in the respective trace +This would result in two files named "prefix-client-eth0.tr" and +"prefix-server-eth0.tr" with traces for each device in the respective trace file. Since all of the EnableAscii functions are overloaded to take a stream wrapper, you can use that form as well: -@verbatim +:: + Names::Add ("client" ...); Names::Add ("client/eth0" ...); Names::Add ("server" ...); @@ -2642,70 +2642,69 @@ you can use that form as well: ... helper.EnableAscii (stream, "client/eth0"); helper.EnableAscii (stream, "server/eth0"); -@end verbatim -This would result in a single trace file called ``trace-file-name.tr'' that +This would result in a single trace file called "trace-file-name.tr" that contains all of the trace events for both devices. The events would be disambiguated by trace context strings. You can enable ascii tracing on a collection of node/net-device pairs by -providing a @code{NetDeviceContainer}. For each @code{NetDevice} in the container +providing a ``NetDeviceContainer``. For each ``NetDevice`` in the container the type is checked. For each device of the proper type (the same type as is -managed by the device helper), tracing is enabled. Again, the @code is -implicit since the found net device must belong to exactly one @code{Node}. +managed by the device helper), tracing is enabled. Again, the ```` is +implicit since the found net device must belong to exactly one ``Node``. For example, -@verbatim +:: + NetDeviceContainer d = ...; ... helper.EnableAscii ("prefix", d); -@end verbatim This would result in a number of ascii trace files being created, each of which follows the --.tr convention. Combining all of the traces into a single file is accomplished similarly to the examples above: -@verbatim +:: + NetDeviceContainer d = ...; ... Ptr stream = asciiTraceHelper.CreateFileStream ("trace-file-name.tr"); ... helper.EnableAscii (stream, d); -@end verbatim You can enable ascii tracing on a collection of node/net-device pairs by -providing a @code{NodeContainer}. For each @code{Node} in the @code{NodeContainer} -its attached @code{NetDevices} are iterated. For each @code{NetDevice} attached +providing a ``NodeContainer``. For each ``Node`` in the ``NodeContainer`` +its attached ``NetDevices`` are iterated. For each ``NetDevice`` attached to each node in the container, the type of that device is checked. For each device of the proper type (the same type as is managed by the device helper), tracing is enabled. -@verbatim +:: + NodeContainer n; ... helper.EnableAscii ("prefix", n); -@end verbatim This would result in a number of ascii trace files being created, each of which follows the --.tr convention. Combining all of the traces into a single file is accomplished similarly to the examples above: You can enable pcap tracing on the basis of node ID and device ID as well as -with explicit @code{Ptr}. Each @code{Node} in the system has an integer node ID +with explicit ``Ptr``. Each ``Node`` in the system has an integer node ID and each device connected to a node has an integer device ID. -@verbatim +:: + helper.EnableAscii ("prefix", 21, 1); -@end verbatim Of course, the traces can be combined into a single file as shown above. Finally, you can enable pcap tracing for all devices in the system, with the same type as that managed by the device helper. -@verbatim +:: + helper.EnableAsciiAll ("prefix"); -@end verbatim This would result in a number of ascii trace files being created, one for every device in the system of the type managed by the helper. All of these @@ -2713,122 +2712,127 @@ files will follow the --.tr convention. Combining all of the traces into a single file is accomplished similarly to the examples above. -@subsubsection Ascii Tracing Device Helper Filename Selection +Ascii Tracing Device Helper Filename Selection +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Implicit in the prefix-style method descriptions above is the construction of the complete filenames by the implementation method. By convention, ascii traces -in the @code{ns-3} system are of the form ``--.tr'' +in the |ns3| system are of the form "--.tr" As previously mentioned, every node in the system will have a system-assigned node id; and every device will have an interface index (also called a device id) relative to its node. By default, then, an ascii trace file created as a result -of enabling tracing on the first device of node 21, using the prefix ``prefix'', -would be ``prefix-21-1.tr''. +of enabling tracing on the first device of node 21, using the prefix "prefix", +would be "prefix-21-1.tr". -You can always use the @code{ns-3} object name service to make this more clear. -For example, if you use the object name service to assign the name ``server'' +You can always use the |ns3| object name service to make this more clear. +For example, if you use the object name service to assign the name "server" to node 21, the resulting ascii trace file name will automatically become, -``prefix-server-1.tr'' and if you also assign the name ``eth0'' to the +"prefix-server-1.tr" and if you also assign the name "eth0" to the device, your ascii trace file name will automatically pick this up and be called -``prefix-server-eth0.tr''. +"prefix-server-eth0.tr". -Several of the methods have a default parameter called @code{explicitFilename}. +Several of the methods have a default parameter called ``explicitFilename``. When set to true, this parameter disables the automatic filename completion mechanism and allows you to create an explicit filename. This option is only available in the methods which take a prefix and enable tracing on a single device. -@subsection Pcap Tracing Protocol Helpers +Pcap Tracing Protocol Helpers ++++++++++++++++++++++++++++++ -The goal of these @code{mixins} is to make it easy to add a consistent pcap trace +The goal of these ``mixins`` is to make it easy to add a consistent pcap trace facility to protocols. We want all of the various flavors of pcap tracing to work the same across all protocols, so the methods of these helpers are -inherited by stack helpers. Take a look at @code{src/helper/trace-helper.h} +inherited by stack helpers. Take a look at ``src/helper/trace-helper.h`` if you want to follow the discussion while looking at real code. In this section we will be illustrating the methods as applied to the protocol -@code{Ipv4}. To specify traces in similar protocols, just substitute the -appropriate type. For example, use a @code{Ptr} instead of a -@code{Ptr} and call @code{EnablePcapIpv6} instead of @code{EnablePcapIpv4}. +``Ipv4``. To specify traces in similar protocols, just substitute the +appropriate type. For example, use a ``Ptr`` instead of a +``Ptr`` and call ``EnablePcapIpv6`` instead of ``EnablePcapIpv4``. -The class @code{PcapHelperForIpv4} provides the high level functionality for -using pcap tracing in the @code{Ipv4} protocol. Each protocol helper enabling these +The class ``PcapHelperForIpv4`` provides the high level functionality for +using pcap tracing in the ``Ipv4`` protocol. Each protocol helper enabling these methods must implement a single virtual method inherited from this class. There -will be a separate implementation for @code{Ipv6}, for example, but the only +will be a separate implementation for ``Ipv6``, for example, but the only difference will be in the method names and signatures. Different method names -are required to disambiguate class @code{Ipv4} from @code{Ipv6} which are both -derived from class @code{Object}, and methods that share the same signature. +are required to disambiguate class ``Ipv4`` from ``Ipv6`` which are both +derived from class ``Object``, and methods that share the same signature. + +:: -@verbatim virtual void EnablePcapIpv4Internal (std::string prefix, Ptr ipv4, uint32_t interface, bool explicitFilename) = 0; -@end verbatim The signature of this method reflects the protocol and interface-centric view of the situation at this level. All of the public methods inherited from class -@code{PcapHelperForIpv4} reduce to calling this single device-dependent +``PcapHelperForIpv4`` reduce to calling this single device-dependent implementation method. For example, the lowest level pcap method, -@verbatim - void EnablePcapIpv4 (std::string prefix, Ptr ipv4, uint32_t interface, bool explicitFilename = false); -@verbatim +:: -will call the device implementation of @code{EnablePcapIpv4Internal} directly. + void EnablePcapIpv4 (std::string prefix, Ptr ipv4, uint32_t interface, bool explicitFilename = false); + + +will call the device implementation of ``EnablePcapIpv4Internal`` directly. All other public pcap tracing methods build on this implementation to provide additional user-level functionality. What this means to the user is that all protocol helpers in the system will have all of the pcap trace methods available; and these methods will all work in the same way across -protocols if the helper implements @code{EnablePcapIpv4Internal} correctly. +protocols if the helper implements ``EnablePcapIpv4Internal`` correctly. -@subsubsection Pcap Tracing Protocol Helper Methods +Pcap Tracing Protocol Helper Methods +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -These methods are designed to be in one-to-one correspondence with the @code{Node}- -and @code{NetDevice}- centric versions of the device versions. Instead of -@code{Node} and @code{NetDevice} pair constraints, we use protocol and interface +These methods are designed to be in one-to-one correspondence with the ``Node``- +and ``NetDevice``- centric versions of the device versions. Instead of +``Node`` and ``NetDevice`` pair constraints, we use protocol and interface constraints. Note that just like in the device version, there are six methods: -@verbatim +:: + void EnablePcapIpv4 (std::string prefix, Ptr ipv4, uint32_t interface, bool explicitFilename = false); void EnablePcapIpv4 (std::string prefix, std::string ipv4Name, uint32_t interface, bool explicitFilename = false); void EnablePcapIpv4 (std::string prefix, Ipv4InterfaceContainer c); void EnablePcapIpv4 (std::string prefix, NodeContainer n); void EnablePcapIpv4 (std::string prefix, uint32_t nodeid, uint32_t interface, bool explicitFilename); void EnablePcapIpv4All (std::string prefix); -@end verbatim -You are encouraged to peruse the Doxygen for class @code{PcapHelperForIpv4} +You are encouraged to peruse the Doxygen for class ``PcapHelperForIpv4`` to find the details of these methods; but to summarize ... You can enable pcap tracing on a particular protocol/interface pair by providing a -@code{Ptr} and @code{interface} to an @code{EnablePcap} method. For example, +``Ptr`` and ``interface`` to an ``EnablePcap`` method. For example, + +:: -@verbatim Ptr ipv4 = node->GetObject (); ... helper.EnablePcapIpv4 ("prefix", ipv4, 0); -@end verbatim You can enable pcap tracing on a particular node/net-device pair by providing a -@code{std::string} representing an object name service string to an -@code{EnablePcap} method. The @code{Ptr} is looked up from the name +``std::string`` representing an object name service string to an +``EnablePcap`` method. The ``Ptr`` is looked up from the name string. For example, -@verbatim +:: + Names::Add ("serverIPv4" ...); ... helper.EnablePcapIpv4 ("prefix", "serverIpv4", 1); -@end verbatim You can enable pcap tracing on a collection of protocol/interface pairs by -providing an @code{Ipv4InterfaceContainer}. For each @code{Ipv4} / interface +providing an ``Ipv4InterfaceContainer``. For each ``Ipv4`` / interface pair in the container the protocol type is checked. For each protocol of the proper type (the same type as is managed by the device helper), tracing is enabled for the corresponding interface. For example, -@verbatim +:: + NodeContainer nodes; ... NetDeviceContainer devices = deviceHelper.Install (nodes); @@ -2838,43 +2842,43 @@ enabled for the corresponding interface. For example, Ipv4InterfaceContainer interfaces = ipv4.Assign (devices); ... helper.EnablePcapIpv4 ("prefix", interfaces); -@end verbatim You can enable pcap tracing on a collection of protocol/interface pairs by -providing a @code{NodeContainer}. For each @code{Node} in the @code{NodeContainer} +providing a ``NodeContainer``. For each ``Node`` in the ``NodeContainer`` the appropriate protocol is found. For each protocol, its interfaces are enumerated and tracing is enabled on the resulting pairs. For example, -@verbatim +:: + NodeContainer n; ... helper.EnablePcapIpv4 ("prefix", n); -@end verbatim You can enable pcap tracing on the basis of node ID and interface as well. In -this case, the node-id is translated to a @code{Ptr} and the appropriate +this case, the node-id is translated to a ``Ptr`` and the appropriate protocol is looked up in the node. The resulting protocol and interface are used to specify the resulting trace source. -@verbatim +:: + helper.EnablePcapIpv4 ("prefix", 21, 1); -@end verbatim Finally, you can enable pcap tracing for all interfaces in the system, with associated protocol being the same type as that managed by the device helper. -@verbatim - helper.EnablePcapIpv4All ("prefix"); -@end verbatim +:: -@subsubsection Pcap Tracing Protocol Helper Filename Selection + helper.EnablePcapIpv4All ("prefix"); + +Pcap Tracing Protocol Helper Filename Selection +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Implicit in all of the method descriptions above is the construction of the complete filenames by the implementation method. By convention, pcap traces -taken for devices in the @code{ns-3} system are of the form -``--.pcap''. In the case of protocol traces, -there is a one-to-one correspondence between protocols and @code{Nodes}. -This is because protocol @code{Objects} are aggregated to @code{Node Objects}. +taken for devices in the |ns3| system are of the form +"--.pcap". In the case of protocol traces, +there is a one-to-one correspondence between protocols and ``Nodes``. +This is because protocol ``Objects`` are aggregated to ``Node Objects``. Since there is no global protocol id in the system, we use the corresponding node id in file naming. Therefore there is a possibility for file name collisions in automatically chosen trace file names. For this reason, the @@ -2888,65 +2892,69 @@ relative to its protocol. We use the convention helpers. Therefore, by default, a pcap trace file created as a result of enabling tracing -on interface 1 of the Ipv4 protocol of node 21 using the prefix ``prefix'' -would be ``prefix-n21-i1.pcap''. +on interface 1 of the Ipv4 protocol of node 21 using the prefix "prefix" +would be "prefix-n21-i1.pcap". -You can always use the @code{ns-3} object name service to make this more clear. -For example, if you use the object name service to assign the name ``serverIpv4'' +You can always use the |ns3| object name service to make this more clear. +For example, if you use the object name service to assign the name "serverIpv4" to the Ptr on node 21, the resulting pcap trace file name will -automatically become, ``prefix-nserverIpv4-i1.pcap''. +automatically become, "prefix-nserverIpv4-i1.pcap". -Several of the methods have a default parameter called @code{explicitFilename}. +Several of the methods have a default parameter called ``explicitFilename``. When set to true, this parameter disables the automatic filename completion mechanism and allows you to create an explicit filename. This option is only available in the methods which take a prefix and enable tracing on a single device. -@subsection Ascii Tracing Protocol Helpers +Ascii Tracing Protocol Helpers +++++++++++++++++++++++++++++++ The behavior of the ascii trace helpers is substantially similar to the pcap -case. Take a look at @code{src/helper/trace-helper.h} if you want to +case. Take a look at ``src/helper/trace-helper.h`` if you want to follow the discussion while looking at real code. In this section we will be illustrating the methods as applied to the protocol -@code{Ipv4}. To specify traces in similar protocols, just substitute the -appropriate type. For example, use a @code{Ptr} instead of a -@code{Ptr} and call @code{EnableAsciiIpv6} instead of @code{EnableAsciiIpv4}. +``Ipv4``. To specify traces in similar protocols, just substitute the +appropriate type. For example, use a ``Ptr`` instead of a +``Ptr`` and call ``EnableAsciiIpv6`` instead of ``EnableAsciiIpv4``. -The class @code{AsciiTraceHelperForIpv4} adds the high level functionality +The class ``AsciiTraceHelperForIpv4`` adds the high level functionality for using ascii tracing to a protocol helper. Each protocol that enables these methods must implement a single virtual method inherited from this class. -@verbatim +:: + virtual void EnableAsciiIpv4Internal (Ptr stream, std::string prefix, Ptr ipv4, uint32_t interface, bool explicitFilename) = 0; -@end verbatim The signature of this method reflects the protocol- and interface-centric view of the situation at this level; and also the fact that the helper may be writing to a shared output stream. All of the public methods inherited from class -@code{PcapAndAsciiTraceHelperForIpv4} reduce to calling this single device- +``PcapAndAsciiTraceHelperForIpv4`` reduce to calling this single device- dependent implementation method. For example, the lowest level ascii trace methods, -@verbatim +:: + void EnableAsciiIpv4 (std::string prefix, Ptr ipv4, uint32_t interface, bool explicitFilename = false); void EnableAsciiIpv4 (Ptr stream, Ptr ipv4, uint32_t interface); -@verbatim -will call the device implementation of @code{EnableAsciiIpv4Internal} directly, + +will call the device implementation of ``EnableAsciiIpv4Internal`` directly, providing either the prefix or the stream. All other public ascii tracing methods will build on these low-level functions to provide additional user-level functionality. What this means to the user is that all device helpers in the system will have all of the ascii trace methods available; and these methods will all work in the same way across protocols if the protocols implement -@code{EnablAsciiIpv4Internal} correctly. +``EnablAsciiIpv4Internal`` correctly. -@subsubsection Ascii Tracing Protocol Helper Methods +Ascii Tracing Protocol Helper Methods +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +:: -@verbatim void EnableAsciiIpv4 (std::string prefix, Ptr ipv4, uint32_t interface, bool explicitFilename = false); void EnableAsciiIpv4 (Ptr stream, Ptr ipv4, uint32_t interface); @@ -2964,9 +2972,8 @@ will all work in the same way across protocols if the protocols implement void EnableAsciiIpv4 (std::string prefix, uint32_t nodeid, uint32_t deviceid, bool explicitFilename); void EnableAsciiIpv4 (Ptr stream, uint32_t nodeid, uint32_t interface); -@end verbatim -You are encouraged to peruse the Doxygen for class @code{PcapAndAsciiHelperForIpv4} +You are encouraged to peruse the Doxygen for class ``PcapAndAsciiHelperForIpv4`` to find the details of these methods; but to summarize ... There are twice as many methods available for ascii tracing as there were for @@ -2978,27 +2985,28 @@ file name generation mechanism is replaced by a mechanism to refer to a common file; and the number of API methods is doubled to allow all combinations. Just as in pcap tracing, you can enable ascii tracing on a particular -protocol/interface pair by providing a @code{Ptr} and an @code{interface} -to an @code{EnableAscii} method. +protocol/interface pair by providing a ``Ptr`` and an ``interface`` +to an ``EnableAscii`` method. For example, -@verbatim +:: + Ptr ipv4; ... helper.EnableAsciiIpv4 ("prefix", ipv4, 1); -@end verbatim In this case, no trace contexts are written to the ascii trace file since they would be redundant. The system will pick the file name to be created using the same rules as described in the pcap section, except that the file will -have the suffix ``.tr'' instead of ``.pcap''. +have the suffix ".tr" instead of ".pcap". If you want to enable ascii tracing on more than one interface and have all traces sent to a single file, you can do that as well by using an object to refer to a single file. We have already something similar to this in the -``cwnd'' example above: +"cwnd" example above: + +:: -@verbatim Ptr protocol1 = node1->GetObject (); Ptr protocol2 = node2->GetObject (); ... @@ -3006,34 +3014,34 @@ refer to a single file. We have already something similar to this in the ... helper.EnableAsciiIpv4 (stream, protocol1, 1); helper.EnableAsciiIpv4 (stream, protocol2, 1); -@verbatim In this case, trace contexts are written to the ascii trace file since they are required to disambiguate traces from the two interfaces. Note that since the user is completely specifying the file name, the string should include the -``,tr'' for consistency. +",tr" for consistency. You can enable ascii tracing on a particular protocol by providing a -@code{std::string} representing an object name service string to an -@code{EnablePcap} method. The @code{Ptr} is looked up from the name -string. The @code in the resulting filenames is implicit since there +``std::string`` representing an object name service string to an +``EnablePcap`` method. The ``Ptr`` is looked up from the name +string. The ```` in the resulting filenames is implicit since there is a one-to-one correspondence between protocol instances and nodes, For example, -@verbatim +:: + Names::Add ("node1Ipv4" ...); Names::Add ("node2Ipv4" ...); ... helper.EnableAsciiIpv4 ("prefix", "node1Ipv4", 1); helper.EnableAsciiIpv4 ("prefix", "node2Ipv4", 1); -@end verbatim -This would result in two files named ``prefix-nnode1Ipv4-i1.tr'' and -``prefix-nnode2Ipv4-i1.tr'' with traces for each interface in the respective +This would result in two files named "prefix-nnode1Ipv4-i1.tr" and +"prefix-nnode2Ipv4-i1.tr" with traces for each interface in the respective trace file. Since all of the EnableAscii functions are overloaded to take a stream wrapper, you can use that form as well: -@verbatim +:: + Names::Add ("node1Ipv4" ...); Names::Add ("node2Ipv4" ...); ... @@ -3041,20 +3049,20 @@ stream wrapper, you can use that form as well: ... helper.EnableAsciiIpv4 (stream, "node1Ipv4", 1); helper.EnableAsciiIpv4 (stream, "node2Ipv4", 1); -@end verbatim -This would result in a single trace file called ``trace-file-name.tr'' that +This would result in a single trace file called "trace-file-name.tr" that contains all of the trace events for both interfaces. The events would be disambiguated by trace context strings. You can enable ascii tracing on a collection of protocol/interface pairs by -providing an @code{Ipv4InterfaceContainer}. For each protocol of the proper +providing an ``Ipv4InterfaceContainer``. For each protocol of the proper type (the same type as is managed by the device helper), tracing is enabled -for the corresponding interface. Again, the @code is implicit since +for the corresponding interface. Again, the ```` is implicit since there is a one-to-one correspondence between each protocol and its node. For example, -@verbatim +:: + NodeContainer nodes; ... NetDeviceContainer devices = deviceHelper.Install (nodes); @@ -3065,13 +3073,13 @@ For example, ... ... helper.EnableAsciiIpv4 ("prefix", interfaces); -@end verbatim This would result in a number of ascii trace files being created, each of which follows the -n-i.tr convention. Combining all of the traces into a single file is accomplished similarly to the examples above: -@verbatim +:: + NodeContainer nodes; ... NetDeviceContainer devices = deviceHelper.Install (nodes); @@ -3083,40 +3091,39 @@ traces into a single file is accomplished similarly to the examples above: Ptr stream = asciiTraceHelper.CreateFileStream ("trace-file-name.tr"); ... helper.EnableAsciiIpv4 (stream, interfaces); -@end verbatim You can enable ascii tracing on a collection of protocol/interface pairs by -providing a @code{NodeContainer}. For each @code{Node} in the @code{NodeContainer} +providing a ``NodeContainer``. For each ``Node`` in the ``NodeContainer`` the appropriate protocol is found. For each protocol, its interfaces are enumerated and tracing is enabled on the resulting pairs. For example, -@verbatim +:: + NodeContainer n; ... helper.EnableAsciiIpv4 ("prefix", n); -@end verbatim This would result in a number of ascii trace files being created, each of which follows the --.tr convention. Combining all of the traces into a single file is accomplished similarly to the examples above: You can enable pcap tracing on the basis of node ID and device ID as well. In -this case, the node-id is translated to a @code{Ptr} and the appropriate +this case, the node-id is translated to a ``Ptr`` and the appropriate protocol is looked up in the node. The resulting protocol and interface are used to specify the resulting trace source. -@verbatim +:: + helper.EnableAsciiIpv4 ("prefix", 21, 1); -@end verbatim Of course, the traces can be combined into a single file as shown above. Finally, you can enable ascii tracing for all interfaces in the system, with associated protocol being the same type as that managed by the device helper. -@verbatim +:: + helper.EnableAsciiIpv4All ("prefix"); -@end verbatim This would result in a number of ascii trace files being created, one for every interface in the system related to a protocol of the type managed by the @@ -3124,38 +3131,36 @@ helper. All of these files will follow the -n-i--.tr'' +in the |ns3| system are of the form "--.tr" As previously mentioned, every node in the system will have a system-assigned node id. Since there is a one-to-one correspondence between protocols and nodes we use to node-id to identify the protocol identity. Every interface on a given protocol will have an interface index (also called simply an interface) relative to its protocol. By default, then, an ascii trace file created as a result -of enabling tracing on the first device of node 21, using the prefix ``prefix'', -would be ``prefix-n21-i1.tr''. Use the prefix to disambiguate multiple protocols +of enabling tracing on the first device of node 21, using the prefix "prefix", +would be "prefix-n21-i1.tr". Use the prefix to disambiguate multiple protocols per node. -You can always use the @code{ns-3} object name service to make this more clear. -For example, if you use the object name service to assign the name ``serverIpv4'' +You can always use the |ns3| object name service to make this more clear. +For example, if you use the object name service to assign the name "serverIpv4" to the protocol on node 21, and also specify interface one, the resulting ascii -trace file name will automatically become, ``prefix-nserverIpv4-1.tr''. +trace file name will automatically become, "prefix-nserverIpv4-1.tr". -Several of the methods have a default parameter called @code{explicitFilename}. +Several of the methods have a default parameter called ``explicitFilename``. When set to true, this parameter disables the automatic filename completion mechanism and allows you to create an explicit filename. This option is only available in the methods which take a prefix and enable tracing on a single device. -@c ============================================================================ -@c Summary -@c ============================================================================ -@node Summary -@section Summary +Summary +******* -@code{ns-3} includes an extremely rich environment allowing users at several +|ns3| includes an extremely rich environment allowing users at several levels to customize the kinds of information that can be extracted from simulations. @@ -3169,6 +3174,6 @@ in a way that will be immediately accessible to users at higher levels. This is a very comprehensive system, and we realize that it is a lot to digest, especially for new users or those not intimately familiar with C++ and its idioms. We do consider the tracing system a very important part of -@code{ns-3} and so recommend becoming as familiar as possible with it. It is -probably the case that understanding the rest of the @code{ns-3} system will +|ns3| and so recommend becoming as familiar as possible with it. It is +probably the case that understanding the rest of the |ns3| system will be quite simple once you have mastered the tracing system diff --git a/doc/tutorial/tweaking.texi b/doc/tutorial/source/tweaking.rst similarity index 64% rename from doc/tutorial/tweaking.texi rename to doc/tutorial/source/tweaking.rst index 84ad60361..499636895 100644 --- a/doc/tutorial/tweaking.texi +++ b/doc/tutorial/source/tweaking.rst @@ -1,51 +1,30 @@ +.. include:: replace.txt -@c ======================================================================== -@c Begin document body here -@c ======================================================================== -@c ======================================================================== -@c PART: Tweaking ns-3 -@c ======================================================================== -@c The below chapters are under the major heading "Tweaking ns-3" -@c This is similar to the Latex \part command -@c -@c ======================================================================== -@c Tweaking ns-3 -@c ======================================================================== -@node Tweaking ns-3 -@chapter Tweaking ns-3 +Tweaking +-------- -@menu -* Using the Logging Module:: -* Using Command Line Arguments:: -* Using the Tracing System:: -@end menu +Using the Logging Module +************************ -@c ======================================================================== -@c Using the Logging Module -@c ======================================================================== -@node Using the Logging Module -@section Using the Logging Module - -@cindex logging -We have already taken a brief look at the @command{ns-3} logging module while -going over the @code{first.cc} script. We will now take a closer look and +We have already taken a brief look at the |ns3| logging module while +going over the ``first.cc`` script. We will now take a closer look and see what kind of use-cases the logging subsystem was designed to cover. -@node Logging Overview -@subsection Logging Overview +Logging Overview +++++++++++++++++ Many large systems support some kind of message logging facility, and -@command{ns-3} is not an exception. In some cases, only error messages are -logged to the ``operator console'' (which is typically @code{stderr} in Unix- +|ns3| is not an exception. In some cases, only error messages are +logged to the "operator console" (which is typically ``stderr`` in Unix- based systems). In other systems, warning messages may be output as well as more detailed informational messages. In some cases, logging facilities are used to output debug messages which can quickly turn the output into a blur. -@command{Ns-3} takes the view that all of these verbosity levels are useful +|ns3| takes the view that all of these verbosity levels are useful and we provide a selectable, multi-level approach to message logging. Logging can be disabled completely, enabled on a component-by-component basis, or enabled globally; and it provides selectable verbosity levels. The -@command{ns-3} log module provides a straightforward, relatively easy to use +|ns3| log module provides a straightforward, relatively easy to use way to get useful information out of your simulation. You should understand that we do provide a general purpose mechanism --- @@ -58,22 +37,18 @@ easily get a quick message out of your scripts or models. There are currently seven levels of log messages of increasing verbosity defined in the system. -@itemize @bullet -@item NS_LOG_ERROR --- Log error messages; -@item NS_LOG_WARN --- Log warning messages; -@item NS_LOG_DEBUG --- Log relatively rare, ad-hoc debugging messages; -@item NS_LOG_INFO --- Log informational messages about program progress; -@item NS_LOG_FUNCTION --- Log a message describing each function called; -@item NS_LOG_LOGIC -- Log messages describing logical flow within a function; -@item NS_LOG_ALL --- Log everything. -@end itemize +* NS_LOG_ERROR --- Log error messages; +* NS_LOG_WARN --- Log warning messages; +* NS_LOG_DEBUG --- Log relatively rare, ad-hoc debugging messages; +* NS_LOG_INFO --- Log informational messages about program progress; +* NS_LOG_FUNCTION --- Log a message describing each function called; +* NS_LOG_LOGIC -- Log messages describing logical flow within a function; +* NS_LOG_ALL --- Log everything. We also provide an unconditional logging level that is always displayed, irrespective of logging levels or component selection. -@itemize @bullet -@item NS_LOG_UNCOND -- Log the associated message unconditionally. -@end itemize +* NS_LOG_UNCOND -- Log the associated message unconditionally. Each level can be requested singly or cumulatively; and logging can be set up using a shell environment variable (NS_LOG) or by logging system function @@ -83,73 +58,73 @@ documentation if you have not done so. Now that you have read the documentation in great detail, let's use some of that knowledge to get some interesting information out of the -@code{scratch/myfirst.cc} example script you have already built. +``scratch/myfirst.cc`` example script you have already built. -@node Enabling Logging -@subsection Enabling Logging -@cindex NS_LOG +Enabling Logging +++++++++++++++++ Let's use the NS_LOG environment variable to turn on some more logging, but first, just to get our bearings, go ahead and run the last script just as you did previously, -@verbatim - ./waf --run scratch/myfirst -@end verbatim +:: -You should see the now familiar output of the first @command{ns-3} example + ./waf --run scratch/myfirst + +You should see the now familiar output of the first |ns3| example program -@verbatim +:: + Waf: Entering directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' 'build' finished successfully (0.413s) Sent 1024 bytes to 10.1.1.2 Received 1024 bytes from 10.1.1.1 Received 1024 bytes from 10.1.1.2 -@end verbatim -It turns out that the ``Sent'' and ``Received'' messages you see above are -actually logging messages from the @code{UdpEchoClientApplication} and -@code{UdpEchoServerApplication}. We can ask the client application, for +It turns out that the "Sent" and "Received" messages you see above are +actually logging messages from the ``UdpEchoClientApplication`` and +``UdpEchoServerApplication``. We can ask the client application, for example, to print more information by setting its logging level via the NS_LOG environment variable. I am going to assume from here on that you are using an sh-like shell that uses -the``VARIABLE=value'' syntax. If you are using a csh-like shell, then you -will have to convert my examples to the ``setenv VARIABLE value'' syntax +the"VARIABLE=value" syntax. If you are using a csh-like shell, then you +will have to convert my examples to the "setenv VARIABLE value" syntax required by those shells. Right now, the UDP echo client application is responding to the following line -of code in @code{scratch/myfirst.cc}, +of code in ``scratch/myfirst.cc``, + +:: -@verbatim LogComponentEnable("UdpEchoClientApplication", LOG_LEVEL_INFO); -@end verbatim -This line of code enables the @code{LOG_LEVEL_INFO} level of logging. When +This line of code enables the ``LOG_LEVEL_INFO`` level of logging. When we pass a logging level flag, we are actually enabling the given level and -all lower levels. In this case, we have enabled @code{NS_LOG_INFO}, -@code{NS_LOG_DEBUG}, @code{NS_LOG_WARN} and @code{NS_LOG_ERROR}. We can +all lower levels. In this case, we have enabled ``NS_LOG_INFO``, +``NS_LOG_DEBUG``, ``NS_LOG_WARN`` and ``NS_LOG_ERROR``. We can increase the logging level and get more information without changing the script and recompiling by setting the NS_LOG environment variable like this: -@verbatim +:: + export NS_LOG=UdpEchoClientApplication=level_all -@end verbatim -This sets the shell environment variable @code{NS_LOG} to the string, +This sets the shell environment variable ``NS_LOG`` to the string, + +:: -@verbatim UdpEchoClientApplication=level_all -@end verbatim The left hand side of the assignment is the name of the logging component we want to set, and the right hand side is the flag we want to use. In this case, we are going to turn on all of the debugging levels for the application. If -you run the script with NS_LOG set this way, the @command{ns-3} logging +you run the script with NS_LOG set this way, the |ns3| logging system will pick up the change and you should see the following output: -@verbatim +:: + Waf: Entering directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' 'build' finished successfully (0.404s) @@ -165,20 +140,19 @@ system will pick up the change and you should see the following output: UdpEchoClientApplication:StopApplication() UdpEchoClientApplication:DoDispose() UdpEchoClientApplication:~UdpEchoClient() -@end verbatim The additional debug information provided by the application is from the NS_LOG_FUNCTION level. This shows every time a function in the application is called during script execution. Note that there are no requirements in the -@command{ns-3} system that models must support any particular logging +|ns3| system that models must support any particular logging functionality. The decision regarding how much information is logged is left to the individual model developer. In the case of the echo applications, a good deal of log output is available. You can now see a log of the function calls that were made to the application. If you look closely you will notice a single colon between the string -@code{UdpEchoClientApplication} and the method name where you might have -expected a C++ scope operator (@code{::}). This is intentional. +``UdpEchoClientApplication`` and the method name where you might have +expected a C++ scope operator (``::``). This is intentional. The name is not actually a class name, it is a logging component name. When there is a one-to-one correspondence between a source file and a class, this @@ -189,13 +163,13 @@ logging component name from the class name. It turns out that in some cases, it can be hard to determine which method actually generates a log message. If you look in the text above, you may -wonder where the string ``@code{Received 1024 bytes from 10.1.1.2}'' comes -from. You can resolve this by OR'ing the @code{prefix_func} level into the -@code{NS_LOG} environment variable. Try doing the following, +wonder where the string "``Received 1024 bytes from 10.1.1.2``" comes +from. You can resolve this by OR'ing the ``prefix_func`` level into the +``NS_LOG`` environment variable. Try doing the following, + +:: -@verbatim export 'NS_LOG=UdpEchoClientApplication=level_all|prefix_func' -@end verbatim Note that the quotes are required since the vertical bar we use to indicate an OR operation is also a Unix pipe connector. @@ -204,7 +178,8 @@ Now, if you run the script you will see that the logging system makes sure that every message from the given log component is prefixed with the component name. -@verbatim +:: + Waf: Entering directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' 'build' finished successfully (0.417s) @@ -220,28 +195,28 @@ name. UdpEchoClientApplication:StopApplication() UdpEchoClientApplication:DoDispose() UdpEchoClientApplication:~UdpEchoClient() -@end verbatim You can now see all of the messages coming from the UDP echo client application -are identified as such. The message ``Received 1024 bytes from 10.1.1.2'' is +are identified as such. The message "Received 1024 bytes from 10.1.1.2" is now clearly identified as coming from the echo client application. The remaining message must be coming from the UDP echo server application. We can enable that component by entering a colon separated list of components in the NS_LOG environment variable. -@verbatim +:: + export 'NS_LOG=UdpEchoClientApplication=level_all|prefix_func: UdpEchoServerApplication=level_all|prefix_func' -@end verbatim -Warning: You will need to remove the newline after the @code{:} in the +Warning: You will need to remove the newline after the ``:`` in the example text above which is only there for document formatting purposes. Now, if you run the script you will see all of the log messages from both the echo client and server applications. You may see that this can be very useful in debugging problems. -@verbatim +:: + Waf: Entering directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' 'build' finished successfully (0.406s) @@ -263,20 +238,20 @@ in debugging problems. UdpEchoServerApplication:DoDispose() UdpEchoClientApplication:~UdpEchoClient() UdpEchoServerApplication:~UdpEchoServer() -@end verbatim It is also sometimes useful to be able to see the simulation time at which a log message is generated. You can do this by ORing in the prefix_time bit. -@verbatim +:: + export 'NS_LOG=UdpEchoClientApplication=level_all|prefix_func|prefix_time: UdpEchoServerApplication=level_all|prefix_func|prefix_time' -@end verbatim Again, you will have to remove the newline above. If you run the script now, you should see the following output: -@verbatim +:: + Waf: Entering directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' 'build' finished successfully (0.418s) @@ -298,35 +273,34 @@ you should see the following output: UdpEchoServerApplication:DoDispose() UdpEchoClientApplication:~UdpEchoClient() UdpEchoServerApplication:~UdpEchoServer() -@end verbatim You can see that the constructor for the UdpEchoServer was called at a simulation time of 0 seconds. This is actually happening before the simulation starts, but the time is displayed as zero seconds. The same is true for the UdpEchoClient constructor message. -Recall that the @code{scratch/first.cc} script started the echo server +Recall that the ``scratch/first.cc`` script started the echo server application at one second into the simulation. You can now see that the -@code{StartApplication} method of the server is, in fact, called at one second. +``StartApplication`` method of the server is, in fact, called at one second. You can also see that the echo client application is started at a simulation time of two seconds as we requested in the script. You can now follow the progress of the simulation from the -@code{ScheduleTransmit} call in the client that calls @code{Send} to the -@code{HandleRead} callback in the echo server application. Note that the +``ScheduleTransmit`` call in the client that calls ``Send`` to the +``HandleRead`` callback in the echo server application. Note that the elapsed time for the packet to be sent across the point-to-point link is 3.69 milliseconds. You see the echo server logging a message telling you that it has echoed the packet and then, after another channel delay, you see the echo -client receive the echoed packet in its @code{HandleRead} method. +client receive the echoed packet in its ``HandleRead`` method. There is a lot that is happening under the covers in this simulation that you are not seeing as well. You can very easily follow the entire process by turning on all of the logging components in the system. Try setting the -@code{NS_LOG} variable to the following, +``NS_LOG`` variable to the following, + +:: -@verbatim export 'NS_LOG=*=level_all|prefix_func|prefix_time' -@end verbatim The asterisk above is the logging component wildcard. This will turn on all of the logging in all of the components used in the simulation. I won't @@ -334,9 +308,9 @@ reproduce the output here (as of this writing it produces 1265 lines of output for the single packet echo) but you can redirect this information into a file and look through it with your favorite editor if you like, -@verbatim +:: + ./waf --run scratch/myfirst > log.out 2>&1 -@end verbatim I personally use this extremely verbose version of logging when I am presented with a problem and I have no idea where things are going wrong. I can follow the @@ -349,67 +323,67 @@ can be especially useful when your script does something completely unexpected. If you are stepping using a debugger you may miss an unexpected excursion completely. Logging the excursion makes it quickly visible. -@node Adding Logging to your Code -@subsection Adding Logging to your Code -@cindex NS_LOG +Adding Logging to your Code ++++++++++++++++++++++++++++ You can add new logging to your simulations by making calls to the log -component via several macros. Let's do so in the @code{myfirst.cc} script we -have in the @code{scratch} directory. +component via several macros. Let's do so in the ``myfirst.cc`` script we +have in the ``scratch`` directory. Recall that we have defined a logging component in that script: -@verbatim +:: + NS_LOG_COMPONENT_DEFINE ("FirstScriptExample"); -@end verbatim You now know that you can enable all of the logging for this component by -setting the @code{NS_LOG} environment variable to the various levels. Let's +setting the ``NS_LOG`` environment variable to the various levels. Let's go ahead and add some logging to the script. The macro used to add an -informational level log message is @code{NS_LOG_INFO}. Go ahead and add one +informational level log message is ``NS_LOG_INFO``. Go ahead and add one (just before we start creating the nodes) that tells you that the script is -``Creating Topology.'' This is done as in this code snippet, +"Creating Topology." This is done as in this code snippet, -Open @code{scratch/myfirst.cc} in your favorite editor and add the line, +Open ``scratch/myfirst.cc`` in your favorite editor and add the line, + +:: -@verbatim NS_LOG_INFO ("Creating Topology"); -@end verbatim right before the lines, -@verbatim +:: + NodeContainer nodes; nodes.Create (2); -@end verbatim -Now build the script using waf and clear the @code{NS_LOG} variable to turn +Now build the script using waf and clear the ``NS_LOG`` variable to turn off the torrent of logging we previously enabled: -@verbatim +:: + ./waf export NS_LOG= -@end verbatim Now, if you run the script, -@verbatim - ./waf --run scratch/myfirst -@end verbatim +:: -you will @emph{not} see your new message since its associated logging -component (@code{FirstScriptExample}) has not been enabled. In order to see your -message you will have to enable the @code{FirstScriptExample} logging component -with a level greater than or equal to @code{NS_LOG_INFO}. If you just want to + ./waf --run scratch/myfirst + +you will ``not`` see your new message since its associated logging +component (``FirstScriptExample``) has not been enabled. In order to see your +message you will have to enable the ``FirstScriptExample`` logging component +with a level greater than or equal to ``NS_LOG_INFO``. If you just want to see this particular level of logging, you can enable it by, -@verbatim - export NS_LOG=FirstScriptExample=info -@end verbatim +:: -If you now run the script you will see your new ``Creating Topology'' log + export NS_LOG=FirstScriptExample=info + +If you now run the script you will see your new "Creating Topology" log message, -@verbatim +:: + Waf: Entering directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' 'build' finished successfully (0.404s) @@ -417,18 +391,14 @@ message, Sent 1024 bytes to 10.1.1.2 Received 1024 bytes from 10.1.1.1 Received 1024 bytes from 10.1.1.2 -@end verbatim -@c ======================================================================== -@c Using Command Line Arguments -@c ======================================================================== -@node Using Command Line Arguments -@section Using Command Line Arguments +Using Command Line Arguments +**************************** -@subsection Overriding Default Attributes -@cindex command line arguments -Another way you can change how @command{ns-3} scripts behave without editing -and building is via @emph{command line arguments.} We provide a mechanism to +Overriding Default Attributes ++++++++++++++++++++++++++++++ +Another way you can change how |ns3| scripts behave without editing +and building is via *command line arguments.* We provide a mechanism to parse command line arguments and automatically set local and global variables based on those arguments. @@ -436,7 +406,8 @@ The first step in using the command line argument system is to declare the command line parser. This is done quite simply (in your main program) as in the following code, -@verbatim +:: + int main (int argc, char *argv[]) { @@ -447,24 +418,24 @@ in the following code, ... } -@end verbatim This simple two line snippet is actually very useful by itself. It opens the -door to the @command{ns-3} global variable and @code{Attribute} systems. Go -ahead and add that two lines of code to the @code{scratch/myfirst.cc} script at -the start of @code{main}. Go ahead and build the script and run it, but ask +door to the |ns3| global variable and ``Attribute`` systems. Go +ahead and add that two lines of code to the ``scratch/myfirst.cc`` script at +the start of ``main``. Go ahead and build the script and run it, but ask the script for help in the following way, -@verbatim +:: + ./waf --run "scratch/myfirst --PrintHelp" -@end verbatim -This will ask Waf to run the @code{scratch/myfirst} script and pass the command -line argument @code{--PrintHelp} to the script. The quotes are required to +This will ask Waf to run the ``scratch/myfirst`` script and pass the command +line argument ``--PrintHelp`` to the script. The quotes are required to sort out which program gets which argument. The command line parser will -now see the @code{--PrintHelp} argument and respond with, +now see the ``--PrintHelp`` argument and respond with, + +:: -@verbatim Waf: Entering directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' 'build' finished successfully (0.413s) @@ -476,48 +447,48 @@ now see the @code{--PrintHelp} argument and respond with, --PrintGroup=[group]: Print all TypeIds of group. --PrintAttributes=[typeid]: Print all attributes of typeid. --PrintGlobals: Print the list of globals. -@end verbatim -Let's focus on the @code{--PrintAttributes} option. We have already hinted -at the @command{ns-3} @code{Attribute} system while walking through the -@code{first.cc} script. We looked at the following lines of code, +Let's focus on the ``--PrintAttributes`` option. We have already hinted +at the |ns3| ``Attribute`` system while walking through the +``first.cc`` script. We looked at the following lines of code, + +:: -@verbatim PointToPointHelper pointToPoint; pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("5Mbps")); pointToPoint.SetChannelAttribute ("Delay", StringValue ("2ms")); -@end verbatim -and mentioned that @code{DataRate} was actually an @code{Attribute} of the -@code{PointToPointNetDevice}. Let's use the command line argument parser -to take a look at the @code{Attributes} of the PointToPointNetDevice. The help -listing says that we should provide a @code{TypeId}. This corresponds to the -class name of the class to which the @code{Attributes} belong. In this case it -will be @code{ns3::PointToPointNetDevice}. Let's go ahead and type in, +and mentioned that ``DataRate`` was actually an ``Attribute`` of the +``PointToPointNetDevice``. Let's use the command line argument parser +to take a look at the ``Attributes`` of the PointToPointNetDevice. The help +listing says that we should provide a ``TypeId``. This corresponds to the +class name of the class to which the ``Attributes`` belong. In this case it +will be ``ns3::PointToPointNetDevice``. Let's go ahead and type in, + +:: -@verbatim ./waf --run "scratch/myfirst --PrintAttributes=ns3::PointToPointNetDevice" -@end verbatim -The system will print out all of the @code{Attributes} of this kind of net device. -Among the @code{Attributes} you will see listed is, +The system will print out all of the ``Attributes`` of this kind of net device. +Among the ``Attributes`` you will see listed is, + +:: -@verbatim --ns3::PointToPointNetDevice::DataRate=[32768bps]: The default data rate for point to point links -@end verbatim -This is the default value that will be used when a @code{PointToPointNetDevice} -is created in the system. We overrode this default with the @code{Attribute} -setting in the @code{PointToPointHelper} above. Let's use the default values +This is the default value that will be used when a ``PointToPointNetDevice`` +is created in the system. We overrode this default with the ``Attribute`` +setting in the ``PointToPointHelper`` above. Let's use the default values for the point-to-point devices and channels by deleting the -@code{SetDeviceAttribute} call and the @code{SetChannelAttribute} call from -the @code{myfirst.cc} we have in the scratch directory. +``SetDeviceAttribute`` call and the ``SetChannelAttribute`` call from +the ``myfirst.cc`` we have in the scratch directory. -Your script should now just declare the @code{PointToPointHelper} and not do -any @code{set} operations as in the following example, +Your script should now just declare the ``PointToPointHelper`` and not do +any ``set`` operations as in the following example, + +:: -@verbatim ... NodeContainer nodes; @@ -529,19 +500,19 @@ any @code{set} operations as in the following example, devices = pointToPoint.Install (nodes); ... -@end verbatim -Go ahead and build the new script with Waf (@code{./waf}) and let's go back +Go ahead and build the new script with Waf (``./waf``) and let's go back and enable some logging from the UDP echo server application and turn on the time prefix. -@verbatim +:: + export 'NS_LOG=UdpEchoServerApplication=level_all|prefix_time' -@end verbatim If you run the script, you should now see the following output, -@verbatim +:: + Waf: Entering directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' 'build' finished successfully (0.405s) @@ -554,58 +525,58 @@ If you run the script, you should now see the following output, 10s UdpEchoServerApplication:StopApplication() UdpEchoServerApplication:DoDispose() UdpEchoServerApplication:~UdpEchoServer() -@end verbatim Recall that the last time we looked at the simulation time at which the packet was received by the echo server, it was at 2.00369 seconds. -@verbatim +:: + 2.00369s UdpEchoServerApplication:HandleRead(): Received 1024 bytes from 10.1.1.1 -@end verbatim Now it is receiving the packet at 2.25732 seconds. This is because we just dropped -the data rate of the @code{PointToPointNetDevice} down to its default of +the data rate of the ``PointToPointNetDevice`` down to its default of 32768 bits per second from five megabits per second. -If we were to provide a new @code{DataRate} using the command line, we could +If we were to provide a new ``DataRate`` using the command line, we could speed our simulation up again. We do this in the following way, according to the formula implied by the help item: -@verbatim - ./waf --run "scratch/myfirst --ns3::PointToPointNetDevice::DataRate=5Mbps" -@end verbatim +:: -This will set the default value of the @code{DataRate} @code{Attribute} back to + ./waf --run "scratch/myfirst --ns3::PointToPointNetDevice::DataRate=5Mbps" + +This will set the default value of the ``DataRate`` ``Attribute`` back to five megabits per second. Are you surprised by the result? It turns out that in order to get the original behavior of the script back, we will have to set the speed-of-light delay of the channel as well. We can ask the command line -system to print out the @code{Attributes} of the channel just like we did for +system to print out the ``Attributes`` of the channel just like we did for the net device: -@verbatim - ./waf --run "scratch/myfirst --PrintAttributes=ns3::PointToPointChannel" -@end verbatim +:: -We discover the @code{Delay} @code{Attribute} of the channel is set in the following + ./waf --run "scratch/myfirst --PrintAttributes=ns3::PointToPointChannel" + +We discover the ``Delay`` ``Attribute`` of the channel is set in the following way: -@verbatim +:: + --ns3::PointToPointChannel::Delay=[0ns]: Transmission delay through the channel -@end verbatim We can then set both of these default values through the command line system, -@verbatim +:: + ./waf --run "scratch/myfirst --ns3::PointToPointNetDevice::DataRate=5Mbps --ns3::PointToPointChannel::Delay=2ms" -@end verbatim in which case we recover the timing we had when we explicitly set the -@code{DataRate} and @code{Delay} in the script: +``DataRate`` and ``Delay`` in the script: + +:: -@verbatim Waf: Entering directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' 'build' finished successfully (0.417s) @@ -618,42 +589,43 @@ in which case we recover the timing we had when we explicitly set the 10s UdpEchoServerApplication:StopApplication() UdpEchoServerApplication:DoDispose() UdpEchoServerApplication:~UdpEchoServer() -@end verbatim Note that the packet is again received by the server at 2.00369 seconds. We -could actually set any of the @code{Attributes} used in the script in this way. -In particular we could set the @code{UdpEchoClient Attribute MaxPackets} +could actually set any of the ``Attributes`` used in the script in this way. +In particular we could set the ``UdpEchoClient Attribute MaxPackets`` to some other value than one. How would you go about that? Give it a try. Remember you have to comment -out the place we override the default @code{Attribute} and explicitly set -@code{MaxPackets} in the script. Then you have to rebuild the script. You +out the place we override the default ``Attribute`` and explicitly set +``MaxPackets`` in the script. Then you have to rebuild the script. You will also have to find the syntax for actually setting the new default attribute value using the command line help facility. Once you have this figured out you should be able to control the number of packets echoed from the command line. Since we're nice folks, we'll tell you that your command line should end up looking something like, -@verbatim +:: + ./waf --run "scratch/myfirst --ns3::PointToPointNetDevice::DataRate=5Mbps --ns3::PointToPointChannel::Delay=2ms --ns3::UdpEchoClient::MaxPackets=2" -@end verbatim -@subsection Hooking Your Own Values +Hooking Your Own Values ++++++++++++++++++++++++ You can also add your own hooks to the command line system. This is done -quite simply by using the @code{AddValue} method to the command line parser. +quite simply by using the ``AddValue`` method to the command line parser. Let's use this facility to specify the number of packets to echo in a -completely different way. Let's add a local variable called @code{nPackets} -to the @code{main} function. We'll initialize it to one to match our previous +completely different way. Let's add a local variable called ``nPackets`` +to the ``main`` function. We'll initialize it to one to match our previous default behavior. To allow the command line parser to change this value, we need to hook the value into the parser. We do this by adding a call to -@code{AddValue}. Go ahead and change the @code{scratch/myfirst.cc} script to +``AddValue``. Go ahead and change the ``scratch/myfirst.cc`` script to start with the following code, -@verbatim +:: + int main (int argc, char *argv[]) { @@ -664,26 +636,26 @@ start with the following code, cmd.Parse (argc, argv); ... -@end verbatim -Scroll down to the point in the script where we set the @code{MaxPackets} -@code{Attribute} and change it so that it is set to the variable @code{nPackets} -instead of the constant @code{1} as is shown below. +Scroll down to the point in the script where we set the ``MaxPackets`` +``Attribute`` and change it so that it is set to the variable ``nPackets`` +instead of the constant ``1`` as is shown below. + +:: -@verbatim echoClient.SetAttribute ("MaxPackets", UintegerValue (nPackets)); -@end verbatim -Now if you run the script and provide the @code{--PrintHelp} argument, you -should see your new @code{User Argument} listed in the help display. +Now if you run the script and provide the ``--PrintHelp`` argument, you +should see your new ``User Argument`` listed in the help display. Try, -@verbatim - ./waf --run "scratch/myfirst --PrintHelp" -@end verbatim +:: + + ./waf --run "scratch/myfirst --PrintHelp" + +:: -@verbatim Waf: Entering directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' 'build' finished successfully (0.403s) @@ -695,18 +667,18 @@ Try, --PrintGlobals: Print the list of globals. User Arguments: --nPackets: Number of packets to echo -@end verbatim If you want to specify the number of packets to echo, you can now do so by -setting the @code{--nPackets} argument in the command line, +setting the ``--nPackets`` argument in the command line, + +:: -@verbatim ./waf --run "scratch/myfirst --nPackets=2" -@end verbatim You should now see -@verbatim +:: + Waf: Entering directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone/ns-3-dev/build' 'build' finished successfully (0.404s) @@ -723,29 +695,26 @@ You should now see 10s UdpEchoServerApplication:StopApplication() UdpEchoServerApplication:DoDispose() UdpEchoServerApplication:~UdpEchoServer() -@end verbatim You have now echoed two packets. Pretty easy, isn't it? -You can see that if you are an @command{ns-3} user, you can use the command -line argument system to control global values and @code{Attributes}. If you are -a model author, you can add new @code{Attributes} to your @code{Objects} and +You can see that if you are an |ns3| user, you can use the command +line argument system to control global values and ``Attributes``. If you are +a model author, you can add new ``Attributes`` to your ``Objects`` and they will automatically be available for setting by your users through the command line system. If you are a script author, you can add new variables to your scripts and hook them into the command line system quite painlessly. -@c ======================================================================== -@c Using the Tracing System -@c ======================================================================== -@node Using the Tracing System -@section Using the Tracing System +Using the Tracing System +************************ The whole point of simulation is to generate output for further study, and -the @command{ns-3} tracing system is a primary mechanism for this. Since -@command{ns-3} is a C++ program, standard facilities for generating output +the |ns3| tracing system is a primary mechanism for this. Since +|ns3| is a C++ program, standard facilities for generating output from C++ programs could be used: -@verbatim +:: + #include ... int main () @@ -754,34 +723,31 @@ from C++ programs could be used: std::cout << "The value of x is " << x << std::endl; ... } -@end verbatim You could even use the logging module to add a little structure to your solution. There are many well-known problems generated by such approaches and so we have provided a generic event tracing subsystem to address the issues we thought were important. -The basic goals of the @command{ns-3} tracing system are: +The basic goals of the |ns3| tracing system are: -@itemize @bullet -@item For basic tasks, the tracing system should allow the user to generate -standard tracing for popular tracing sources, and to customize which objects -generate the tracing; -@item Intermediate users must be able to extend the tracing system to modify -the output format generated, or to insert new tracing sources, without -modifying the core of the simulator; -@item Advanced users can modify the simulator core to add new tracing sources -and sinks. -@end itemize +* For basic tasks, the tracing system should allow the user to generate + standard tracing for popular tracing sources, and to customize which objects + generate the tracing; +* Intermediate users must be able to extend the tracing system to modify + the output format generated, or to insert new tracing sources, without + modifying the core of the simulator; +* Advanced users can modify the simulator core to add new tracing sources + and sinks. -The @command{ns-3} tracing system is built on the concepts of independent +The |ns3| tracing system is built on the concepts of independent tracing sources and tracing sinks, and a uniform mechanism for connecting sources to sinks. Trace sources are entities that can signal events that happen in a simulation and provide access to interesting underlying data. For example, a trace source could indicate when a packet is received by a net device and provide access to the packet contents for interested trace sinks. -Trace sources are not useful by themselves, they must be ``connected'' to +Trace sources are not useful by themselves, they must be "connected" to other pieces of code that actually do something useful with the information provided by the sink. Trace sinks are consumers of the events and data provided by the trace sources. For example, one could create a trace sink @@ -800,93 +766,85 @@ show how they may be customized with little user effort. See the ns-3 manual or how-to sections for information on advanced tracing configuration including extending the tracing namespace and creating new tracing sources. -@cindex tracing -@cindex ASCII tracing -@subsection ASCII Tracing -@command{Ns-3} provides helper functionality that wraps the low-level tracing +ASCII Tracing ++++++++++++++ +|ns3| provides helper functionality that wraps the low-level tracing system to help you with the details involved in configuring some easily understood packet traces. If you enable this functionality, you will see output in a ASCII files --- thus the name. For those familiar with -@command{ns-2} output, this type of trace is analogous to the @command{out.tr} +|ns2| output, this type of trace is analogous to the ``out.tr`` generated by many scripts. -@cindex tracing packets Let's just jump right in and add some ASCII tracing output to our -@code{scratch/myfirst.cc} script. Right before the call to -@code{Simulator::Run ()}, add the following lines of code: +``scratch/myfirst.cc`` script. Right before the call to +``Simulator::Run ()``, add the following lines of code: + +:: -@verbatim AsciiTraceHelper ascii; pointToPoint.EnableAsciiAll (ascii.CreateFileStream ("myfirst.tr")); -@end verbatim -Like in many other @command{ns-3} idioms, this code uses a helper object to +Like in many other |ns3| idioms, this code uses a helper object to help create ASCII traces. The second line contains two nested method calls. -The ``inside'' method, @code{CreateFileStream()} uses an unnamed object idiom +The "inside" method, ``CreateFileStream()`` uses an unnamed object idiom to create a file stream object on the stack (without an object name) and pass it down to the called method. We'll go into this more in the future, but all you have to know at this point is that you are creating an object representing -a file named ``myfirst.tr'' and passing it into @code{ns-3}. You are telling -@code{ns-3} to deal with the lifetime issues of the created object and also to +a file named "myfirst.tr" and passing it into ``ns-3``. You are telling +``ns-3`` to deal with the lifetime issues of the created object and also to deal with problems caused by a little-known (intentional) limitation of C++ ofstream objects relating to copy constructors. -The outside call, to @code{EnableAsciiAll()}, tells the helper that you +The outside call, to ``EnableAsciiAll()``, tells the helper that you want to enable ASCII tracing on all point-to-point devices in your simulation; and you want the (provided) trace sinks to write out information about packet movement in ASCII format. -For those familiar with @command{ns-2}, the traced events are equivalent to +For those familiar with |ns2|, the traced events are equivalent to the popular trace points that log "+", "-", "d", and "r" events. You can now build the script and run it from the command line: -@verbatim - ./waf --run scratch/myfirst -@end verbatim +:: + + ./waf --run scratch/myfirst -@cindex myfirst.tr Just as you have seen many times before, you will see some messages from Waf and then -``'build' finished successfully'' with some number of messages from +"'build' finished successfully" with some number of messages from the running program. -When it ran, the program will have created a file named @code{myfirst.tr}. +When it ran, the program will have created a file named ``myfirst.tr``. Because of the way that Waf works, the file is not created in the local directory, it is created at the top-level directory of the repository by default. If you want to control where the traces are saved you can use the -@code{--cwd} option of Waf to specify this. We have not done so, thus we +``--cwd`` option of Waf to specify this. We have not done so, thus we need to change into the top level directory of our repo and take a look at -the ASCII trace file @code{myfirst.tr} in your favorite editor. +the ASCII trace file ``myfirst.tr`` in your favorite editor. -@subsubsection Parsing Ascii Traces -@cindex parsing ascii traces +Parsing Ascii Traces +~~~~~~~~~~~~~~~~~~~~ There's a lot of information there in a pretty dense form, but the first thing to notice is that there are a number of distinct lines in this file. It may be difficult to see this clearly unless you widen your window considerably. -Each line in the file corresponds to a @emph{trace event}. In this case -we are tracing events on the @emph{transmit queue} present in every +Each line in the file corresponds to a *trace event*. In this case +we are tracing events on the *transmit queue* present in every point-to-point net device in the simulation. The transmit queue is a queue through which every packet destined for a point-to-point channel must pass. Note that each line in the trace file begins with a lone character (has a space after it). This character will have the following meaning: -@cindex ascii trace enqueue operation -@cindex ascii trace dequeue operation -@cindex ascii trace drop operation -@cindex ascii trace receive operation -@itemize @bullet -@item @code{+}: An enqueue operation occurred on the device queue; -@item @code{-}: A dequeue operation occurred on the device queue; -@item @code{d}: A packet was dropped, typically because the queue was full; -@item @code{r}: A packet was received by the net device. -@end itemize +* ``+``: An enqueue operation occurred on the device queue; +* ``-``: A dequeue operation occurred on the device queue; +* ``d``: A packet was dropped, typically because the queue was full; +* ``r``: A packet was received by the net device. Let's take a more detailed view of the first line in the trace file. I'll break it down into sections (indented for clarity) with a two digit reference number on the left side: -@verbatim +:: + 00 + 01 2 02 /NodeList/0/DeviceList/0/$ns3::PointToPointNetDevice/TxQueue/Enqueue @@ -898,38 +856,32 @@ number on the left side: 08 ns3::UdpHeader ( 09 length: 1032 49153 > 9) 10 Payload (size=1024) -@end verbatim -@cindex trace event -@cindex simulation time The first line of this expanded trace event (reference number 00) is the -operation. We have a @code{+} character, so this corresponds to an -@emph{enqueue} operation on the transmit queue. The second line (reference 01) +operation. We have a ``+`` character, so this corresponds to an +*enqueue* operation on the transmit queue. The second line (reference 01) is the simulation time expressed in seconds. You may recall that we asked the -@code{UdpEchoClientApplication} to start sending packets at two seconds. Here +``UdpEchoClientApplication`` to start sending packets at two seconds. Here we see confirmation that this is, indeed, happening. -@cindex node number -@cindex net device number -@cindex smart pointer The next line of the example trace (reference 02) tell us which trace source originated this event (expressed in the tracing namespace). You can think of the tracing namespace somewhat like you would a filesystem namespace. The -root of the namespace is the @code{NodeList}. This corresponds to a container -managed in the @command{ns-3} core code that contains all of the nodes that are +root of the namespace is the ``NodeList``. This corresponds to a container +managed in the |ns3| core code that contains all of the nodes that are created in a script. Just as a filesystem may have directories under the -root, we may have node numbers in the @code{NodeList}. The string -@code{/NodeList/0} therefore refers to the zeroth node in the @code{NodeList} -which we typically think of as ``node 0''. In each node there is a list of +root, we may have node numbers in the ``NodeList``. The string +``/NodeList/0`` therefore refers to the zeroth node in the ``NodeList`` +which we typically think of as "node 0". In each node there is a list of devices that have been installed. This list appears next in the namespace. -You can see that this trace event comes from @code{DeviceList/0} which is the +You can see that this trace event comes from ``DeviceList/0`` which is the zeroth device installed in the node. -The next string, @code{$ns3::PointToPointNetDevice} tells you what kind of +The next string, ``$ns3::PointToPointNetDevice`` tells you what kind of device is in the zeroth position of the device list for node zero. -Recall that the operation @code{+} found at reference 00 meant that an enqueue +Recall that the operation ``+`` found at reference 00 meant that an enqueue operation happened on the transmit queue of the device. This is reflected in -the final segments of the ``trace path'' which are @code{TxQueue/Enqueue}. +the final segments of the "trace path" which are ``TxQueue/Enqueue``. The remaining lines in the trace should be fairly intuitive. References 03-04 indicate that the packet is encapsulated in the point-to-point protocol. @@ -944,7 +896,8 @@ transmit queue on the same node. The Third line in the trace file shows the packet being received by the net device on the node with the echo server. I have reproduced that event below. -@verbatim +:: + 00 r 01 2.25732 02 /NodeList/1/DeviceList/0/$ns3::PointToPointNetDevice/MacRx @@ -954,69 +907,67 @@ device on the node with the echo server. I have reproduced that event below. 06 ns3::UdpHeader ( 07 length: 1032 49153 > 9) 08 Payload (size=1024) -@end verbatim -Notice that the trace operation is now @code{r} and the simulation time has +Notice that the trace operation is now ``r`` and the simulation time has increased to 2.25732 seconds. If you have been following the tutorial steps -closely this means that you have left the @code{DataRate} of the net devices -and the channel @code{Delay} set to their default values. This time should +closely this means that you have left the ``DataRate`` of the net devices +and the channel ``Delay`` set to their default values. This time should be familiar as you have seen it before in a previous section. The trace source namespace entry (reference 02) has changed to reflect that -this event is coming from node 1 (@code{/NodeList/1}) and the packet reception -trace source (@code{/MacRx}). It should be quite easy for you to follow the +this event is coming from node 1 (``/NodeList/1``) and the packet reception +trace source (``/MacRx``). It should be quite easy for you to follow the progress of the packet through the topology by looking at the rest of the traces in the file. -@subsection PCAP Tracing -@cindex pcap -@cindex Wireshark -The @command{ns-3} device helpers can also be used to create trace files in the -@code{.pcap} format. The acronym pcap (usually written in lower case) stands -for @emph{p}acket @emph{cap}ture, and is actually an API that includes the -definition of a @code{.pcap} file format. The most popular program that can +PCAP Tracing +++++++++++++ +The |ns3| device helpers can also be used to create trace files in the +``.pcap`` format. The acronym pcap (usually written in lower case) stands +for packet capture, and is actually an API that includes the +definition of a ``.pcap`` file format. The most popular program that can read and display this format is Wireshark (formerly called Ethereal). However, there are many traffic trace analyzers that use this packet format. We encourage users to exploit the many tools available for analyzing pcap traces. In this tutorial, we concentrate on viewing pcap traces with tcpdump. -@cindex pcap tracing The code used to enable pcap tracing is a one-liner. -@verbatim +:: + pointToPoint.EnablePcapAll ("myfirst"); -@end verbatim Go ahead and insert this line of code after the ASCII tracing code we just -added to @code{scratch/myfirst.cc}. Notice that we only passed the string -``myfirst,'' and not ``myfirst.pcap'' or something similar. This is because the +added to ``scratch/myfirst.cc``. Notice that we only passed the string +"myfirst," and not "myfirst.pcap" or something similar. This is because the parameter is a prefix, not a complete file name. The helper will actually create a trace file for every point-to-point device in the simulation. The file names will be built using the prefix, the node number, the device number -and a ``.pcap'' suffix. +and a ".pcap" suffix. -In our example script, we will eventually see files named ``myfirst-0-0.pcap'' -and ``myfirst-1-0.pcap'' which are the pcap traces for node 0-device 0 and +In our example script, we will eventually see files named "myfirst-0-0.pcap" +and "myfirst-1-0.pcap" which are the pcap traces for node 0-device 0 and node 1-device 0, respectively. Once you have added the line of code to enable pcap tracing, you can run the script in the usual way: -@verbatim +:: + ./waf --run scratch/myfirst -@end verbatim If you look at the top level directory of your distribution, you should now -see three log files: @code{myfirst.tr} is the ASCII trace file we have -previously examined. @code{myfirst-0-0.pcap} and @code{myfirst-1-0.pcap} +see three log files: ``myfirst.tr`` is the ASCII trace file we have +previously examined. ``myfirst-0-0.pcap`` and ``myfirst-1-0.pcap`` are the new pcap files we just generated. -@subsubsection Reading output with tcpdump -@cindex tcpdump -The easiest thing to do at this point will be to use @code{tcpdump} to look -at the @code{pcap} files. +Reading output with tcpdump +~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The easiest thing to do at this point will be to use ``tcpdump`` to look +at the ``pcap`` files. + +:: -@verbatim tcpdump -nn -tt -r myfirst-0-0.pcap reading from file myfirst-0-0.pcap, link-type PPP (PPP) 2.000000 IP 10.1.1.1.49153 > 10.1.1.2.9: UDP, length 1024 @@ -1026,21 +977,20 @@ at the @code{pcap} files. reading from file myfirst-1-0.pcap, link-type PPP (PPP) 2.257324 IP 10.1.1.1.49153 > 10.1.1.2.9: UDP, length 1024 2.257324 IP 10.1.1.2.9 > 10.1.1.1.49153: UDP, length 1024 -@end verbatim -You can see in the dump of @code{myfirst-0-0.pcap} (the client device) that the +You can see in the dump of ``myfirst-0-0.pcap`` (the client device) that the echo packet is sent at 2 seconds into the simulation. If you look at the -second dump (@code{myfirst-1-0.pcap}) you can see that packet being received +second dump (``myfirst-1-0.pcap``) you can see that packet being received at 2.257324 seconds. You see the packet being echoed back at 2.257324 seconds in the second dump, and finally, you see the packet being received back at the client in the first dump at 2.514648 seconds. -@subsubsection Reading output with Wireshark -@cindex Wireshark +Reading output with Wireshark +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ If you are unfamiliar with Wireshark, there is a web site available from which -you can download programs and documentation: @uref{http://www.wireshark.org/}. +you can download programs and documentation: http://www.wireshark.org/. Wireshark is a graphical user interface which can be used for displaying these trace files. If you have Wireshark available, you can open each of the trace files and display the contents as if you had captured the packets using a -@emph{packet sniffer}. +*packet sniffer*. diff --git a/doc/tutorial/tutorial.css b/doc/tutorial/tutorial.css deleted file mode 100644 index a7586ac83..000000000 --- a/doc/tutorial/tutorial.css +++ /dev/null @@ -1,156 +0,0 @@ -body { - font-family: "Trebuchet MS", "Bitstream Vera Sans", verdana, lucida, arial, helvetica, sans-serif; - background: white; - color: black; - font-size: 11pt; -} - -h1, h2, h3, h4, h5, h6 { -# color: #990000; - color: #009999; -} - -pre { - font-size: 10pt; - background: #e0e0e0; - color: black; -} - -a:link, a:visited { - font-weight: normal; - text-decoration: none; - color: #0047b9; -} - -a:hover { - font-weight: normal; - text-decoration: underline; - color: #0047b9; -} - -img { - border: 0px; -} - -#main th { - font-size: 12pt; - background: #b0b0b0; -} - -.odd { - font-size: 12pt; - background: white; -} - -.even { - font-size: 12pt; - background: #e0e0e0; -} - -.answer { - font-size: large; - font-weight: bold; -} - -.answer p { - font-size: 12pt; - font-weight: normal; -} - -.answer ul { - font-size: 12pt; - font-weight: normal; -} - -#container { - position: absolute; - width: 100%; - height: 100%; - top: 0px; -} - -#feedback { - color: #b0b0b0; - font-size: 9pt; - font-style: italic; -} - -#header { - position: absolute; - margin: 0px; - top: 10px; - height:96px; - left: 175px; - right: 10em; - bottom: auto; - background: white; - clear: both; -} - -#middle { - position: absolute; - left: 0; - height: auto; - width: 100%; -} - -#main { - position: absolute; - top: 50px; - left: 175px; - right: 100px; - background: white; - padding: 0em 0em 0em 0em; -} - -#navbar { - position: absolute; - top: 75px; - left: 0em; - width: 146px; - padding: 0px; - margin: 0px; - font-size: 10pt; -} - -#navbar a:link, #navbar a:visited { - font-weight: normal; - text-decoration: none; - color: #0047b9; -} - -#navbar a:hover { - font-weight: normal; - text-decoration: underline; - color: #0047b9; -} - -#navbar dl { - width: 146px; - padding: 0; - margin: 0 0 10px 0px; - background: #99ffff url(images/box_bottom2.gif) no-repeat bottom left; -} - -#navbar dt { - padding: 6px 10px; - font-size: 100%; - font-weight: bold; - background: #009999; - margin: 0px; - border-bottom: 1px solid #fff; - color: white; - background: #009999 url(images/box_top2.gif) no-repeat top left; -} - -#navbar dd { - font-size: 100%; - margin: 0 0 0 0px; - padding: 6px 10px; - color: #0047b9; -} - -dd#selected { - background: #99ffff url(images/arrow.gif) no-repeat; - background-position: 4px 10px; -} diff --git a/doc/tutorial/tutorial.texi b/doc/tutorial/tutorial.texi deleted file mode 100644 index f4fca50b0..000000000 --- a/doc/tutorial/tutorial.texi +++ /dev/null @@ -1,106 +0,0 @@ -\input texinfo @c -*-texinfo-*- -@c %**start of header -@setfilename ns-3.info -@settitle ns-3 tutorial -@c @setchapternewpage odd -@c %**end of header - -@ifinfo -Primary documentation for the @command{ns-3} project is available in -four forms: -@itemize @bullet -@item @uref{http://www.nsnam.org/doxygen/index.html,,ns-3 Doxygen/Manual}: Documentation of the public APIs of the simulator -@item Tutorial (this document) -@item @uref{http://www.nsnam.org/docs/manual.html,,Reference Manual}: Reference Manual -@item @uref{http://www.nsnam.org/wiki/index.php,, ns-3 wiki} -@end itemize - -This document is written in GNU Texinfo and is to be maintained in revision -control on the @command{ns-3} code server. Both PDF and HTML versions should -be available on the server. Changes to the document should be discussed on -the ns-developers@@isi.edu mailing list. -@end ifinfo - -@copying - -This is an @command{ns-3} tutorial. -Primary documentation for the @command{ns-3} project is available in -four forms: -@itemize @bullet -@item @uref{http://www.nsnam.org/doxygen/index.html,,ns-3 Doxygen/Manual}: Documentation of the public APIs of the simulator -@item Tutorial (this document) -@item @uref{http://www.nsnam.org/docs/manual.html,,Reference Manual}: Reference Manual -@item @uref{http://www.nsnam.org/wiki/index.php,, ns-3 wiki} -@end itemize - -This document is written in GNU Texinfo and is to be maintained in revision -control on the @command{ns-3} code server. Both PDF and HTML versions should -be available on the server. Changes to the document should be discussed on -the ns-developers@@isi.edu mailing list. - -This software is free software; you can redistribute it and/or modify -it under the terms of the GNU General Public License as published by -the Free Software Foundation; either version 2 of the License, or -(at your option) any later version. - -This software is distributed in the hope that it will be useful, -but WITHOUT ANY WARRANTY; without even the implied warranty of -MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -GNU General Public License for more details. - -You should have received a copy of the GNU General Public License -along with this program. If not, see @uref{http://www.gnu.org/licenses/}. -@end copying - -@titlepage -@title ns-3 Tutorial -@author ns-3 project -@author feedback: ns-developers@@isi.edu -@today{} - -@c @page -@vskip 0pt plus 1filll -@insertcopying -@end titlepage - -@c So the toc is printed at the start. -@ifnottex -@anchor{Full Table of Contents} -@end ifnottex -@contents - -@ifnottex -@node Top, Introduction, Full Table of Contents -@top ns-3 Tutorial (html version) - -For a pdf version of this tutorial, -see @uref{http://www.nsnam.org/docs/tutorial.pdf}. - -@insertcopying -@end ifnottex - -@menu -* Introduction:: -* Resources:: -* Getting Started:: -* Conceptual Overview:: -* Tweaking ns-3:: -* Building Topologies:: -* The Tracing System:: -* Closing Remarks:: -* Index:: -@end menu - -@include introduction.texi -@include getting-started.texi -@include conceptual-overview.texi -@include tweaking.texi -@include building-topologies.texi -@include tracing.texi -@include conclusion.texi - -@node Index -@unnumbered Index -@printindex cp - -@bye