/**
 * \mainpage An Introduction to ns-3
 *
 * The ns-3 library is split across multiple modules:
 *     - core: located in src/core and contains a number of facilities which
 *       do not depend on any other module. Some of these facilities are
 *       OS-dependent.
 *     - simulator: located in src/simulator and contains event scheduling
 *       facilities.
 *     - common: located in src/common and contains facilities specific
 *       to network simulations but shared by pretty much every model
 *       of a network component.
 *     - node: located in src/node. Contains an ipv4/udp model.
 *     - devices: located in src/devices. Contains a set of MAC-level models
 *
 * The "core" module contains:
 *    - a Functor class: ns3::Callback
 *    - an os-independent interface to get access to the elapsed wall clock time: ns3::SystemWallClockMs
 *    - a class to register regression tests with the test manager: ns3::Test and ns3::TestManager
 *    - debugging facilities: \ref debugging, \ref assert, \ref error
 *    - \ref randomvariable
 *    - a class to handle automatic deletion of multiple sets of objects of different types: 
 *      ns3::ObjectContainer
 *
 * The "simulator" module contains:
 *    - a time management class to hold a time and convert between various time units: ns3::Time
 *    - a scheduler base class used to implement new simulation event schedulers: 
 *      ns3::Scheduler and ns3::SchedulerFactory
 *    - a simulator class used to create, schedule and cancel events: ns3::Simulator
 *
 * The "common" module contains:
 *    - a packet class to create and manipulate simulation packets: ns3::Packet, ns3::Header, 
 *      and ns3::Trailer
 *    - a set of low-level trace facilities: \ref lowleveltracing
 *
 * The "node" module contains:
 *    - a ns3::Node base class and an ns3::InternetNode implementation which model
 *      network nodes.
 *    - a set of models contained in InternetNode: ns3::Ipv4, ns3::Udp, ns3::L3Demux,
 *      ns3::L3Protocol, ns3::Ipv4L4Demux, ns3::Ipv4L4Protocol, ns3::Ipv4Interface,
 *      ns3::DatagramSocket
 *    - models which abstract the MAC-layer from the IP layer protocols:
 *      ns3::NetDevice and ns3::Channel.
 *    - an Arp model if the underlying NetDevice object needs it: ns3::ArpIpv4Interface
 *    - a set of traffic generation models: ns3::OnOffApplication
 *
 * The "devices" module contains:
 *    - a PointToPoint MAC device: ns3::PointToPointNetDevice, ns3::PointToPointChannel,
 *      and ns3::PointToPointTopology.
 */
/**
 * \namespace ns3
 * \brief Every class exported by the ns3 library is enclosed in the
 * ns3 namespace.
 */
/**
 * \defgroup constants Constants
 * \brief Constants you can change
 */