Next we need to paste the below code to the Main.tcl file and save the file in the ns-2.35 folder.

Code:

set ns [new Simulator]

set namfile [open out.nam w]

$ns namtrace-all $namfile

set tracefile [open out.tr w]

$ns trace-all $tracefile

proc finish {} {

    global ns tracefile namfile

    $ns flush-trace

    close $tracefile

    close $namfile

    exec nam out.nam &

    exit 0

}

set n0 [$ns node]

set n1 [$ns node]

set n2 [$ns node]

set n3 [$ns node]

$ns color 0 magenta

# Define link layer object for MAC layer simulation

set ll [new LL]

$ll set macType Mac/802_11

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

$ns duplex-link $n1 $n2 1Mb 10ms DropTail

$ns duplex-link $n2 $n3 1Mb 10ms DropTail

$ns duplex-link $n3 $n0 1Mb 10ms DropTail

$ns queue-limit $n0 $n1 50

$ns queue-limit $n1 $n2 50

$ns queue-limit $n2 $n3 50

$ns queue-limit $n3 $n0 50

set udp0 [new Agent/UDP]

$ns attach-agent $n0 $udp0

set cbr0 [new Application/Traffic/CBR]

$cbr0 set packetSize_ 500

$cbr0 set rate_ 1Mb

$cbr0 attach-agent $udp0

set null0 [new Agent/Null]

$ns attach-agent $n2 $null0

$ns connect $udp0 $null0

set udp1 [new Agent/UDP]

$ns attach-agent $n1 $udp1

set cbr1 [new Application/Traffic/CBR]

$cbr1 set packetSize_ 500

$cbr1 set rate_ 1Mb

$cbr1 attach-agent $udp1

set null1 [new Agent/Null]

$ns attach-agent $n3 $null1

$ns connect $udp1 $null1

$ns at 0.5 “$cbr0 start”

$ns at 1.0 “$cbr1 start”

$ns at 4.5 “$cbr0 stop”

$ns at 4.8 “$cbr1 stop”

$ns at 5.0 “finish”

$ns run 

Screenshot: