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] 

$ns color 0 purple 

$ns color 1 lightblue 

$ns color 2 green 

set n0 [$ns node] 

set n1 [$ns node] 

set n2 [$ns node] 

set n3 [$ns node]

set n4 [$ns node] 

set f [open out.tr w] 

$ns trace-all $f 

set nf [open out.nam w] 

$ns namtrace-all $nf 

$ns duplex-link $n0 $n2 5Mb 2ms DropTail

$ns duplex-link $n1 $n2 5Mb 2ms DropTail 

$ns duplex-link $n2 $n3 1.5Mb 10ms DropTail

$ns duplex-link $n3 $n4 2.5Mb 5ms DropTail 

$ns duplex-link-op $n0 $n2 orient right-up 

$ns duplex-link-op $n1 $n2 orient right-down 

$ns duplex-link-op $n2 $n3 orient right 

$ns duplex-link-op $n2 $n3 queuePos 0.5

$ns duplex-link-op $n3 $n4 queuePos 0.9 

set udp0 [new Agent/UDP] 

$ns attach-agent $n0 $udp0 

set cbr0 [new Application/Traffic/CBR] 

$cbr0 attach-agent $udp0 

set udp1 [new Agent/UDP] 

$ns attach-agent $n4 $udp1 

$udp1 set class_ 1 

set cbr1 [new Application/Traffic/CBR] 

$cbr1 attach-agent $udp1 

set null0 [new Agent/Null] 

$ns attach-agent $n4 $null0 

set null1 [new Agent/Null] 

$ns attach-agent $n1 $null1 

$ns connect $udp0 $null0 

$ns connect $udp1 $null1 

$ns at 1.0 “$cbr0 start” 

$ns at 1.1 “$cbr1 start” 

set tcp [new Agent/TCP] 

$tcp set class_ 2 

set sink [new Agent/TCPSink] 

$ns attach-agent $n0 $tcp 

$ns attach-agent $n4 $sink 

$ns connect $tcp $sink 

set ftp [new Application/FTP] 

$ftp attach-agent $tcp 

$ns at 1.2 “$ftp start” 

$ns at 1.35 “$ns detach-agent $n0 $tcp ; $ns detach-agent $n4 $sink” 

puts [$cbr0 set packetSize_] 

puts [$cbr0 set interval_] 

$ns at 3.0 “finish” 

proc finish {} { 

               global ns f nf 

               $ns flush-trace 

               close $f 

               close $nf 

               puts “running nam…” 

               exec nam out.nam & 

               exit 0 

} 

$ns run 

 Screenshot: