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 nf [open out.nam w]

$ns namtrace-all $nf

set tracefile [open out.tr w]

$ns trace-all $tracefile

proc finish {} {

    global ns nf tracefile

    $ns flush-trace

    close $tracefile

    close $nf

    exec nam out.nam &

    exit 0}

set n0 [$ns node]

set n1 [$ns node] 

set n2 [$ns node]

set n3 [$ns node]

set n4 [$ns node]

set n5 [$ns node]

set n6 [$ns node]

set n7 [$ns node]

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

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

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

$ns simplex-link $n3 $n4 1Mb 10ms DropTail

$ns simplex-link $n4 $n5 1Mb 10ms DropTail

$ns simplex-link $n5 $n6 1Mb 10ms DropTail

$ns simplex-link $n6 $n7 1Mb 10ms DropTail

$ns simplex-link $n7 $n0 1Mb 10ms DropTail

$ns rtproto LS

set tcp0 [new Agent/TCP] ;# Create TCP agents and attach them to nodes

$ns attach-agent $n0 $tcp0

set tcp1 [new Agent/TCP]

$ns attach-agent $n7 $tcp1

set cbr0 [new Application/Traffic/CBR] ;# Create a TCP traffic generator and attach it to the TCP agent

$cbr0 set packetSize_ 1000

$cbr0 set rate_ 500Kb

$cbr0 attach-agent $tcp0

set null0 [new Agent/Null]

$ns attach-agent $n7 $null0 ; # Connect the TCP agents

$ns connect $tcp0 $null0

$ns at 1.0 “$cbr0 start”

$ns at 10.0 “$cbr0 stop”

$ns at 12.0 “finish”

$ns run

Screenshot: