Experiment-2

Using Free Open Source Software tools for network simulation – I Preliminary usage of the tool ns3 Simulate telnet and ftp between N sources – N sinks (N = 1, 2, 3). Evaluate the effect of increasing data rate on congestion.

Objectives

• Get a basic understanding of the way objectives interact in ns.
• Lay the foundations for more complicated simulations.
• Create a script that simulates the simplest topology

Network:

#Create NS Object :

set ns [new Simulator]

#Open the nam trace file

set nf [open out.nam w]

$ns namtrace-all $nf

#Define a ‘finish’ procedure

proc finish {} {

global ns nf

$ns flush-trace

#Close the trace file

close $nf

#Execute nam on the trace file

exec nam –a out.nam &

exit 0

}

#Create two nodes

set n0 [$ns node]

set n1 [$ns node]

#Create a duplex link between the nodes

$ns duplex-link $n0 $n1 1Mb 10ms DropTail

#Call the finish procedure after 5 seconds of simulation time

$ns at 5.0 “finish”

#Run the simulation

$ns run

#Execute a ns-2 script:

 ns example1a.tcl

PART-B :  To attach traffic from node 0 to node 1

set ns [new Simulator]

#open Trace Files

set f [open out.tr w]

$ns trace-all $f

set nf [open out.nam w]

$ns namtrace-all $nf

#define “finish” procedure

proc finish {} {

global ns

$ns flush-trace

#Execute the nam animation file

exec nam out.nam &

exit 0

}

#creating Node

set n0 [$ns node]

set n1 [$ns node]

#creating link and Queue

$ns duplex-link $n0 $n1 1Mb 10ms DropTail

#create UDP agent and attach it to nod 0

set udp0 [new Agent/UDP]

$ns attach-agent $n0 $udp0

#Adding Traffic to link

#create cbr traffic source and attach it to udp0

set cbr0 [new Application/Traffic/CBR]

$cbr0 set packetSize_ 500

$cbr0 set interval_ 0.005500

$cbr0 attach-agent $udp0

 

 

 

#Adding Traffic to link ; create null agent (a traffic sink) and attach it to node n1

set null0 [new Agent/Null]

$ns attach-agent $n1 $null0

#connect traffic source with the traffic sink

$ns connect $udp0 $null0

 

 

 

#schedule event for CBR agent

$ns at 0.5 “$cbr0 start”

$ns at 4.5 “$cbr0 stop”

$ns at 5.0 “finish”

#start ns

$ns run

#stop ns

exit 0