Tcl demo code

first.tcl

# The preamble
 
set ns [new Simulator]                                                               ;#initialise the simulation
 
# Predefine tracing
set f [open out.tr w]
$ns trace-all $f
set nf [open out.nam w]
$ns namtrace-all $nf
 
set n0 [$ns node]
set n1 [$ns node]
set n2 [$ns node]
set n3 [$ns node]
 
$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
 
# Some agents.
 
set udp0 [new Agent/UDP]                                                                                    ;#A UDP agent
$ns attach-agent $n0 $udp0                                                                                 ;#on node $n0
set cbr0 [new Application/Traffic/CBR]                          ;#A CBR traffic generator agent
$cbr0 attach-agent $udp0                                                           ;#attached to the UDP agent
$udp0 set class_ 0                                                                             ;#actually, the default, but.
 
set null0 [new Agent/Null]                                                                                              ;#Its sink
$ns attach-agent $n3 $null0                                                                                  ;#on node $n3
 
$ns connect $udp0 $null0
$ns at 1.0 "$cbr0 start"
 
puts [$cbr0 set packetSize_]
puts [$cbr0 set interval_]
 
# A FTP over TCP/Tahoe from $n1 to $n3, flowid 2
set tcp [new Agent/TCP]
$tcp set class_ 1
$ns attach-agent $n1 $tcp
 
set sink [new Agent/TCPSink]
$ns attach-agent $n3 $sink
 
set ftp [new Application/FTP]                               ;#TCP does not generate its own traffic
$ftp attach-agent $tcp
$ns at 1.2 "$ftp start"
 
$ns connect $tcp $sink
$ns at 1.35 "$ns detach-agent $n0 $tcp ; $ns detach-agent $n3 $sink"
 
# The simulation runs for3s.
# The simulation comes to an end when the scheduler invokes the finish{} method.
# This procedure closes all trace files, and invokes nam visualization on trace files.
 
$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
}
 
# Finally, start the simulation.
$ns run