#Create a simulator object
set ns [new Simulator]
#Tell the simulator to use dynamic routing
$ns rtproto DV
#Open the nam trace file
set nf [open out.nam w]
$ns namtrace-all $nf
#Define a ’finish’ procedure
proc finish {} {
global ns nf
$ns flush-trace
#Close the trace file
close $nf
#Execute nam on the trace file
exec nam out.nam &
exit 0
}
#RING TOPOLOGY (Topologie Anneau)
# IMPORTANT : 1- Remarquez que les noeuds sont d´efinis sur un tableau
# 2- ESSAYEZ DE REFAIRE LA MEME BOUCLE AVEC UN WHILE
#Create eight nodes
for {set i 0} {$i < 8} {incr i} {
set n($i) [$ns node]
}
#Create links between the nodes
for {set i 0} {$i < 8} {incr i} {
$ns duplex-link $n($i) $n([expr ($i+1)%8]) 1Mb 10ms DropTail
}
#Create a UDP agent and attach it to node n(0)
set udp0 [new Agent/UDP]
$ns attach-agent $n(0) $udp0
# Create a CBR traffic source and attach it to udp0
set cbr0 [new Application/Traffic/CBR]
$cbr0 set packetSize_ 500
$cbr0 set interval_ 0.005
$cbr0 attach-agent $udp0

#Create a Null agent (a traffic sink) and attach it to node n(3)
set null0 [new Agent/Null]
$ns attach-agent $n(3) $null0
#Connect the traffic source with the traffic sink
$ns connect $udp0 $null0
#Schedule events for the CBR agent and the network dynamics
$ns at 0.5 "$cbr0 start"
$ns rtmodel-at 1.0 down $n(1) $n(2)
$ns rtmodel-at 2.0 up $n(1) $n(2)
$ns at 4.5 "$cbr0 stop"
#Call the finish procedure after 5 seconds of simulation time
$ns at 5.0 "finish"
#Run the simulation
$ns run