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

proc finish {} {

    global ns nf

    $ns flush-trace

    close $nf

    exec nam out.nam &

    exit 0}

set topo [new Topography]

$topo load_flatgrid 1000 1000

set rng [new RNG]                ;# Random number generator object & Create a random variable generator

$rng seed 0                      ;# Seed the RNG

set num_nodes 5

set nodes [list]

for {set i 0} {$i < $num_nodes} {incr i} {

    set n [$ns node]

    lappend nodes $n

    set xpos [expr {int([$rng uniform 0 1000])}]

    set ypos [expr {int([$rng uniform 0 1000])}]

    $n set X_ $xpos

    $n set Y_ $ypos

    $n set Z_ 0

    puts “Node $i placed at position ($xpos, $ypos)”}

for {set i 0} {$i < [expr {$num_nodes – 1}]} {incr i} {

    $ns duplex-link [lindex $nodes $i] [lindex $nodes [expr {$i + 1}]] 1Mb 10ms DropTail}

set udp0 [new Agent/UDP]

$ns attach-agent [lindex $nodes 0] $udp0

set null0 [new Agent/Null]

$ns attach-agent [lindex $nodes 4] $null0

$ns connect $udp0 $null0

set cbr [new Application/Traffic/CBR]

$cbr set packetSize_ 512

$cbr set rate_ 1Mb

$cbr attach-agent $udp0

$ns at 0.1 “$cbr start”

$ns at 4.0 “$cbr stop”

$ns at 5.0 “finish”

$ns run

Screenshot: