Program 2

2. Implement transmission of ping messages/trace route over a network topology consisting of 6 nodes and find the number of packets dropped due to congestion.

set ns [new Simulator]
set nf [open lab2.nam w]
$ns namtrace-all $nf
set tf [open lab2.tr w]
$ns trace-all $tf
set n0 [$ns node]
set n1 [$ns node]
set n2 [$ns node]
set n3 [$ns node]
set n4 [$ns node]
set n5 [$ns node]
$n4 shape box

$ns duplex-link $n0 $n4 1005Mb 1ms DropTail
$ns duplex-link $n1 $n4 5Mb 1ms DropTail
$ns duplex-link $n2 $n4 20Mb 1ms DropTail
$ns duplex-link $n3 $n4 20Mb 1ms DropTail
$ns duplex-link $n5 $n4 1Mb 1ms DropTail
set p0 [new Agent/Ping]
$ns attach-agent $n0 $p0
$p0 set packetSize_ 5000
$p0 set interval_ 0.001
set p1 [new Agent/Ping]
$ns attach-agent $n1 $p1
set p2 [new Agent/Ping]
$ns attach-agent $n2 $p2
$p2 set packetSize_ 50000
$p2 set interval_ 0.0001
set p3 [new Agent/Ping]
$ns attach-agent $n3 $p3
set p4 [new Agent/Ping]
$ns attach-agent $n4 $p4
$ns queue-limit $n0 $n4 1ms
$ns queue-limit $n2 $n4 2ms
$ns queue-limit $n4 $n3 1ms
Agent/Ping inst var proc{from rtt} {
$selfinstvar node_
puts"[$node_id]received answer from $from round trip time $rtt msec"
}
$ns connect $p0 $p4
$ns connect $p2 $p3
proc finish { } {
global ns nf tf
$ns flush-trace
close $nf
close $tf
exec nam lab2.nam &
exit 0
}
$ns at 0.1 "$p0 send"
$ns at 0.2 "$p0 send"
$ns at 0.3 "$p0 send"
$ns at 0.4 "$p0 send"
$ns at 0.5 "$p0 send"
$ns at 0.6 "$p0 send"
$ns at 0.7 "$p0 send"
$ns at 0.8 "$p0 send"
$ns at 0.9 "$p0 send"
$ns at 1.0 "$p0 send"
$ns at 0.1 "$p2 send"
$ns at 0.2 "$p2 send"
$ns at 0.3 "$p2 send"
$ns at 0.4 "$p2 send"
$ns at 0.5 "$p2 send"
$ns at 0.6 "$p2 send"
$ns at 0.7 "$p2 send"
$ns at 0.8 "$p2 send"
$ns at 0.9 "$p2 send"
$ns at 1.0 "$p2 send"
$ns at 1.3 "finish"
$ns run

AWK file (Open a new editor using “gedit command” and write awk file and save with “.awk” extension) 

BEGIN{
drop=0;
}
{
 if($1=="d")
{
   drop++;
}
}
END{
printf("total no of %s packets dropped due to congestion=%d\n",drop,$5);
}