update NSC documentation

src/internet/doc/tcp.rst

@@ -172,24 +172,49 @@ network stacks by hand. Not a single line of code has been changed in the
 network protocol implementations of any of the above four stacks. However, a
 custom C parser was built to programmatically change source code.
 
-NSC has previously been ported to |ns2| and OMNeT++, and recently 
-was added to |ns3|.  This section describes the |ns3| port of NSC and
-how to use it.
+NSC has previously been ported to |ns2| and OMNeT++, and was 
+was added to |ns3| in September 2008 (ns-3.2 release).  This section 
+describes the |ns3| port of NSC and how to use it.
+
+To some extent, NSC has been superseded by the Linux kernel support within 
+`Direct Code Execution (DCE) <http://www.nsnam.org/docs/dce/manual/singlehtml/index.html>`_.  However, NSC is still available through the bake build
+system.  NSC supports Linux kernels 2.6.18 and 2.6.26, but newer
+versions of the kernel have not been ported.  
 
 Prerequisites
 +++++++++++++
 
 Presently, NSC has been tested and shown to work on these platforms:
-Linux i386 and Linux x86-64. NSC does not support powerpc.
+Linux i386 and Linux x86-64.  NSC does not support powerpc.  Use on
+FreeBSD or OS X is unsupported (although it may be able to work).
 
 Building NSC requires the packages flex and bison.  
 
 Configuring and Downloading
 +++++++++++++++++++++++++++
 
-Using the ``build.py`` script in ns-3-allinone directory, NSC will be enabled by
-default unless the platform does not support it. To disable it when building
-|ns3|, type:
+As of ns-3.17 or later, NSC must either be downloaded separately from
+its own repository, or downloading when using the bake build system of 
+|ns3|.  
+
+For ns-3.17 or later, when using bake, one must configure NSC as part of
+an "allinone" configuration, such as:
+
+.. sourcecode:: bash
+
+  $ cd bake
+  $ python bake.py configure -e ns-allinone-3.19
+  $ python bake.py download
+  $ python bake.py build
+
+Instead of a released version, one may use the ns-3 development version
+by specifying "ns-3-allinone" to the configure step above.
+
+NSC may also be downloaded and built using 
+
+Prior to ns-3.17 release, using the ``build.py`` script in ns-3-allinone 
+directory, NSC will be enabled by default unless the platform does not 
+support it. To disable it when building |ns3|, type:
 
 .. sourcecode:: bash
 
@@ -198,11 +223,42 @@ default unless the platform does not support it. To disable it when building
 Building and validating
 +++++++++++++++++++++++
 
-Building |ns3| with nsc support is the same as building it without; no
-additional arguments are needed for waf. Building nsc may take some time
-compared to |ns3|; it is interleaved in the |ns3| building process.
+NSC may be built as part of the bake build process; alternatively, one
+may build NSC by itself using its build system; e.g.:
 
-Try running the following ns-3 test suite:
+.. sourcecode:: bash
+
+  $ cd nsc-dev
+  $ python scons.py
+
+Once NSC has been built either manually or through the bake system, change
+into the |ns3| source directory and try running the following configuration:
+
+.. sourcecode:: bash
+
+  $ ./waf configure
+
+If NSC has been previously built and found by waf, then you will see:
+
+.. sourcecode:: bash
+
+  Network Simulation Cradle     : enabled
+
+If NSC has not been found, you will see:
+
+.. sourcecode:: bash
+
+  Network Simulation Cradle     : not enabled (NSC not found (see option --with-nsc))
+
+In this case, you must pass the relative or absolute path to the NSC libraries
+with the "--with-nsc" configure option; e.g.
+
+.. sourcecode:: bash
+
+  $ ./waf configure --with-nsc=/path/to/my/nsc/directory
+
+If waf detects NSC, then building |ns3| with NSC is the same as building it
+without.  Once |ns3| is built, try running the following test suite:
 
 .. sourcecode:: bash
 
@@ -374,7 +430,7 @@ Limitations
 
 * NSC only works on single-interface nodes; attempting to run it on a
   multi-interface node will cause a program error.  
-* Cygwin and OS X PPC are not supported
+* Cygwin and OS X PPC are not supported; OS X Intel is not supported but may work
 * The non-Linux stacks of NSC are not supported in |ns3|
 * Not all socket API callbacks are supported