INTRODUCTION TO NETWORK SIMULATOR-2

What is ns?

Object-oriented, discrete event driven network simulator

It was normally used in wired & wireless protocol Written in C++ and OTcl

ADVANTAGES

1. Debugging of errors makes easy,2. It is cheap doesnot not require any

equipment,3. Even an complex scenario can be

tested effiently.

ns Architecture

Tcl

OTcl

TclCL

ns-2

Event

Sch

ed

ule

rNetwork Components

C/C++

Simulation NetworkWired Network

◦Routing: Distance Vector, Link State◦Transportation: TCP and UDP◦Queuing disciplines: drop-tail

Wireless◦Ad-hoc routing and mobile IP: AODV◦Sensor-MAC, WiMAX (new)◦Power control in wireless networks

NS2 Functionalities

Traffic models and applications◦FTP, CBR

Transport protocols◦Unicast: TCP, UDP

Routing and queuing◦Wired and ad-hoc routing◦Queuing protocols: drop-tail, etc

Physical media◦Wired (point-to-point, LANs), wireless (multiple propagation models), satellite

Ns – structure

Types1. Event Schedular2. Turn on Tracing3. Network Topology4.Transport Connection5. Generate Traffic6.Start Simulation

Attaching Transport Agents to Nodes-tcp/udp

TCP :set src [new Agent/TCP/FullTcp]set sink [new Agent/TCP/FullTcp]$ns_ attach-agent $node_(s1) $src$ns_ attach-agent $node_(k1) $sink$ns_ connect $src $sink

Udp agent

Set udp0 [new Agent/Null]ns attach-agent $n0 $udp0set cbr0 [new Application/Traffic/CBR]$cbr0 attach-agent $udp0$udp0 set packetSize_ 536 ; #(max=1000)set null0 [new Agent/Null]$ns attach-agent $n1 $null0$ns connect $udp0 $null0

PACKETS

It is the collection of data,whether header is called or not all header files where present in the stack registers.

Cmn header

Ip header

Tcp header

Rtp header

Trace header

Header

data

Trace Analysis

Trace packets on individual linkTracefile format:

NAM

ns has a companion network animator called nam

hence, has been called the nsnam project

Xgraph

One part of the ns-allinone package is 'xgraph', a plotting program which can be used to create graphic representations of simulation results.