/**

 * \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. Defines the abstract interfaces which 

 *       must be implemented by every node and more specifically, by ipv4 nodes.       

 *     - 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

 *    - \ref config

 *    - a base class for objects which need to support reference counting 

 *      and QueryInterface: ns3::Object and ns3::InterfaceId

 *    - a ns3::ComponentManager which can be used to manage the creation

 *      of any object which derives from ns3::Object through an ns3::ClassId

 *    - a smart-pointer class ns3::Ptr designed to work together with ns3::Object

 *

 * 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. This packet class also supports per-packet ns3::Tag which are

 *      globs of data which can be attached to any packet.

 *    - a set of low-level trace facilities: \ref lowleveltracing

 *

 * The "node" module contains:

 *    - a ns3::Node base class which should be subclassed by any new type of

 *      network Node.

 *    - models which abstract the MAC-layer from the IP layer protocols:

 *      ns3::NetDevice and ns3::Channel.

 *    - models which abstract the application-layer API: ns3::Application,

 *      ns3::Socket, ns3::SocketFactory, and, ns3::Udp

 *

 * The "internet-node" module contains a set of classes which implement the

 * APIs defined in the "node" module:

 *    - an Ipv4/Udp stack with socket support

 *    - an ARP module

 *    - an InternetNode class which is a Node subclass. 

 *

 * 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

 */