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] # Create a NS object for simulator

set nf [open out.nam w]

$ns namtrace-all $nf

set tf [open out.tr w]

$ns trace-all $tf

proc finish {} {

    global ns nf tf

    $ns flush-trace

    close $nf

    close $tf

    exec nam out.nam &

    exit 0}

set n0 [$ns node]

set n1 [$ns node]

set n2 [$ns node]

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

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

$ns queue-limit $n0 $n1 20

$ns queue-limit $n1 $n2 20

set udp0 [new Agent/UDP]

set udp1 [new Agent/UDP]

$ns attach-agent $n0 $udp0

$ns attach-agent $n1 $udp1

set cbr0 [new Application/Traffic/CBR]

$cbr0 set packetSize_ 512

$cbr0 set interval_ 0.01

$cbr0 attach-agent $udp0

set cbr1 [new Application/Traffic/CBR]

$cbr1 set packetSize_ 512

$cbr1 set interval_ 0.01

$cbr1 attach-agent $udp1

set null0 [new Agent/Null]

$ns attach-agent $n2 $null0

$ns connect $udp0 $null0

$ns connect $udp1 $null0

$ns at 0.5 “$cbr0 start”

$ns at 1.0 “$cbr1 start”

$ns at 10.0 “finish”

$ns run

Screenshot: