INTRODUCTION

Network simulator covers a very large number of applications, protocols, network types, network elements and traffic models.
Ns simulator is based on two languages an object oriented simulator, written in C++, and a OTcl interpreter object oriented extension of Tcl.

TOOL COMMAND LANGUAGE:
Tcl is a language with very simple syntax and it allows very easy integration with other language.
OTcl script is written in particular network topology and specific protocol and applications wish to simulates.
It allows fast development
It provides graphical interface
It is compatible with many platforms
It is flexible for integration
It is easy to use
It is free

NS SIMULATOR PRELIMINARIES:
Initialization and termination aspects of ns simulator
Network nodes Queues, link and topology
Agent and application
Nam visualization tool
Tracing and
Random variables

TRANSPORT CONTROL PROTOCOL/INTERNET PROTOCOL:
Adapt the transmission rate of packets to the available bandwidth.
Avoid congestion at network
Create reliable connection by retransmitting lost packets.


WIRELESS SENSOR NETWORK (WSN):
WSN are spatially distributed autonomous sensors to monitor physical or environmental conditions, such as temperature, sound, pressure, etc. and to cooperatively pass their data through the network to a main location.

MOBILE AD HOC NETWORK (MANET):
A mobile ad hoc network is a continuously self-configuring, infrastructure-less network of mobile devices connected without wires.

VEHICULAR AD HOC NETWORKS (VANET):
VANETs are created by applying the principles of mobile ad hoc networks (MANETs) the spontaneous creation of a wireless network for data exchange - to the domain of vehicles. They are a key component of intelligent transportation systems (ITS).

SOFTWARE REQUIREMENTS:

Operating system - VMWARE/UBUNTU.
Implementation - NS2
NS2 Version - NS2.34
Front End - OTCL (Object Oriented Tool Command Language)