set ns [new Simulator -multicast on]

set f [open out.tr w]
$ns trace-all $f
$ns namtrace-all [open out.nam w]

$ns color 1 red
# prune/graft packets
$ns color 30 purple
$ns color 31 bisque

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

# Use automatic layout
$ns duplex-link $n0 $n1 1.5Mb 10ms DropTail
$ns duplex-link $n1 $n2 1.5Mb 10ms DropTail
$ns duplex-link $n1 $n3 1.5Mb 10ms DropTail

$ns duplex-link-op $n0 $n1 orient right
$ns duplex-link-op $n1 $n2 orient right-up
$ns duplex-link-op $n1 $n3 orient right-down
$ns duplex-link-op $n0 $n1 queuePos 0.5

set mproto DM
set mrthandle [$ns mrtproto $mproto {}]
set group0 [Node allocaddr]
set group1 [Node allocaddr]

set udp0 [new Agent/UDP]
$ns attach-agent $n1 $udp0
$udp0 set dst_addr_ $group0
$udp0 set dst_port_ 0
set cbr0 [new Application/Traffic/CBR]
$cbr0 attach-agent $udp0

set udp1 [new Agent/UDP]
$udp1 set dst_addr_ $group1
$udp1 set dst_port_ 0
$udp1 set class_ 1
$ns attach-agent $n3 $udp1
set cbr1 [new Application/Traffic/CBR]
$cbr1 attach-agent $udp1

set rcvr [new Agent/LossMonitor]
$ns attach-agent $n2 $rcvr
$ns at 1.2 “$n2 join-group $rcvr $group1”
$ns at 1.25 “$n2 leave-group $rcvr $group1”
$ns at 1.3 “$n2 join-group $rcvr $group1”
$ns at 1.35 “$n2 join-group $rcvr $group0”

$ns at 1.0 “$cbr0 start”
#$ns at 1.001 “$cbr0 stop”
$ns at 1.1 “$cbr1 start”

#set tcp [new Agent/TCP]
#set sink [new Agent/TCPSink]
#$ns attach-agent $n0 $tcp
#$ns attach-agent $n3 $sink
#$ns connect $tcp $sink
#set ftp [new Application/FTP]
#$ftp attach-agent $tcp
#$ns at 1.2 “$ftp start”

#puts [$cbr0 set packetSize_]
#puts [$cbr0 set interval_]

$ns at 2.0 “finish”

proc finish {} {
global ns
$ns flush-trace

puts “running nam…”
exec nam out.nam &
exit 0
}

$ns run