Execute Tcl Online

set ns [new Simulator]

set tf [open main.tf w]
$ns trace-all $tf

set nf [open main.nam w]
$ns namtrace-all $nf

set n0 [$ns node]
set n1 [$ns node]
set n2 [$ns node]
set n3 [$ns node]

$ns make-lan "$n0 $n1 $n2 $n3" 10Mb 10ms LL
Queue/DropTail Mac/802_3

$n0 label "source1"
$n2 label "source2"
$n1 label "destination1"
$n3 label "destination2"
$ns color 1 "red"
$ns color 2 "blue"

set tcp0 [new Agent/TCP]
$ns attach-agent $n0 $tcp0
set tcp2 [new Agent/TCP]
$ns attach-agent $n2 $tcp2
set sink1 [new Agent/TCPSink]
$ns attach-agent $n1 $sink1
set sink3 [new Agent/TCPSink]
$ns attach-agent $n3 $sink3

set ftp0 [new Application/FTP]
$ftp0 attach-agent $tcp0
set ftp2 [new Application/FTP]
$ftp2 attach-agent $tcp2

$ns connect $tcp0 $sink3
$ns connect $tcp2 $sink1
$tcp0 set class_ 1
$tcp2 set class_ 2

set file0 [open file0.tr w]
$tcp0 attach $file0
$tcp0 trace cwnd_
$tcp0 set maxcwnd_ 10
set file2 [open file2.tr w]
$tcp2 attach $file2 
$tcp2 trace cwnd_

proc finish { } {
	global ns nf tf
	$ns flush-trace	
	exec nam main.nam &
	close $nf
	exit 0 }

$ns at 0.1 "$ftp0 start"
$ns at 1.5 "$ftp0 stop"
$ns at 2 "$ftp0 start"
$ns at 3 "$ftp0 stop"
$ns at 0.2 "$ftp2 start"
$ns at 2 "$ftp2 stop"
$ns at 2.5 "$ftp2 start"
$ns at 4 "$ftp2 stop"
$ns at 5.0 "finish"
$ns run