# Pragmatic General Multicast (PGM), Reliable Multicast## Example to demonstrate Constrained NAK forwarding, NAK elmination,# and NAK suppression.## Ryan S. Barnett, 2001# rbarnett@catarina.usc.eduset ns [new Simulator -multicast on]$ns node-config -PGM ON$ns namtrace-all [open out.nam w]$ns color 0 red$ns color 1 black$ns color 2 white$ns color 3 blue$ns color 4 yellow$ns color 5 LightBlue$ns color 6 green$ns color 7 magenta$ns color 8 orangeset colors { red black white blue yellow LightBlue green magenta orange }set group [Node allocaddr]puts "Group addr: $group"proc makelinks { bw delay pairs } {        global ns n        foreach p $pairs {                set src $n([lindex $p 0])                set dst $n([lindex $p 1])                $ns duplex-link $src $dst $bw $delay DropTail        }}proc disable-pgm { pairs } {    global n    foreach p $pairs {	set agent [$n($p) get-pgm]	$agent set pgm_enabled_ 0    }}proc create-receiver {rcv i group} {   upvar $rcv r   global ns n   set r [new Agent/PGM/Receiver]   $r set nak_bo_ivl_ 100ms   $ns attach-agent $n($i) $r   $ns at 0.01 "$n($i) join-group $r $group"   $n($i) color "blue"}# Create nodes.for {set k 0} { $k < 12 } { incr k } {    set n($k) [$ns node]    $n($k) shape "circle"    $n($k) color "green"}makelinks 1.5Mb 10ms {    { 0 1 }    { 1 2 }    { 1 3 }    { 2 4 }    { 3 8 }    { 2 5 }    { 2 6 }    { 2 7 }    { 3 9 }    { 3 10 }    { 3 11 }}$ns duplex-link-op $n(0) $n(1) color "red"$ns duplex-link-op $n(0) $n(1) orient down$ns duplex-link-op $n(1) $n(2) orient left-down$ns duplex-link-op $n(1) $n(3) orient right-down$ns duplex-link-op $n(2) $n(4) orient left$ns duplex-link-op $n(3) $n(8) orient left# Set routing protocol.set mproto DMset mrthandle [$ns mrtproto $mproto {}]# Create sender.set src0 [new Agent/PGM/Sender]$ns attach-agent $n(0) $src0$src0 set dst_addr_ $group$src0 set dst_port_ 0$src0 set set rdata_delay_ 40msset cbr0 [new Application/Traffic/CBR]$cbr0 attach-agent $src0$cbr0 set rate_ 448Kb$cbr0 set packetSize_ 210$cbr0 set random_ 0$n(0) color "magenta"# Create receivers.create-receiver rcv4 4 $groupcreate-receiver rcv5 5 $groupcreate-receiver rcv6 6 $groupcreate-receiver rcv7 7 $groupcreate-receiver rcv8 8 $groupcreate-receiver rcv9 9 $groupcreate-receiver rcv10 10 $groupcreate-receiver rcv11 11 $group# Disable Agent/PGM on receivers.disable-pgm { 4 5 6 7 8 9 10 11 }# Disable Agent/PGM on sender.disable-pgm { 0 }# Disable Agent/PGM on Node 2.disable-pgm { 2 }$n(2) color "black"# Create a lossy link between 0 and 1.set loss_module [new PGMErrorModel]# Drop the third ODATA packet going on this link.$loss_module drop-packet ODATA 50 3$loss_module drop-target [$ns set nullAgent_]$ns lossmodel $loss_module $n(0) $n(1)$ns at 0.2 "$src0 start-SPM"$ns at 0.25 "$cbr0 start"$ns at 0.4 "$cbr0 stop"$ns at 0.45 "$src0 stop-SPM"$ns at 0.5 "finish"proc finish {} {    exit 0}$ns run