Code:

set val(stop)   7.0                         ;# time of simulation end  #=================================== #        Initialization         #=================================== #Create a ns simulator set ns [new Simulator]  #Open the NS trace file set tracefile [open wr5nodes.tr w] $ns trace-all $tracefile  #Open the NAM trace file set namfile [open wr5nodes.nam w] $ns namtrace-all $namfile  #=================================== #        Nodes Definition         #=================================== #Create 5 nodes set n0 [$ns node] set n1 [$ns node] set n2 [$ns node] set n3 [$ns node] set n4 [$ns node]  #=================================== #        Links Definition         #=================================== #Createlinks between nodes $ns duplex-link $n0 $n1 100.0Mb 10ms DropTail $ns queue-limit $n0 $n1 50 $ns duplex-link $n1 $n2 100.0Mb 10ms DropTail $ns queue-limit $n1 $n2 50 $ns duplex-link $n1 $n3 100.0Mb 10ms DropTail $ns queue-limit $n1 $n3 50 $ns duplex-link $n1 $n4 100.0Mb 10ms DropTail $ns queue-limit $n1 $n4 50  #Give node position (for NAM) $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 $ns duplex-link-op $n1 $n4 orient right-downset tcp [new Agent/TCP]set tcpsink [new Agent/TCPSink]$ns attach-agent $n0 $tcp$ns attach-agent $n1 $tcpsink$ns connect $tcp $tcpsinkset tcp1 [new Agent/TCP]set tcpsink1 [new Agent/TCPSink]$ns attach-agent $n1 $tcp1$ns attach-agent $n2 $tcpsink1$ns connect $tcp1 $tcpsink1set tcp2 [new Agent/TCP]set tcpsink2 [new Agent/TCPSink]$ns attach-agent $n1 $tcp2$ns attach-agent $n4 $tcpsink2$ns connect $tcp2 $tcpsink2set tcp3 [new Agent/TCP]set tcpsink3 [new Agent/TCPSink]$ns attach-agent $n2 $tcp3$ns attach-agent $n1 $tcpsink3$ns connect $tcp3 $tcpsink3set tcp4 [new Agent/TCP]set tcpsink4 [new Agent/TCPSink]$ns attach-agent $n1 $tcp4$ns attach-agent $n0 $tcpsink4$ns connect $tcp4 $tcpsink4set tcp5 [new Agent/TCP]set tcpsink5 [new Agent/TCPSink]$ns attach-agent $n0 $tcp5$ns attach-agent $n1 $tcpsink5$ns connect $tcp5 $tcpsink5set tcp6 [new Agent/TCP]set tcpsink6 [new Agent/TCPSink]$ns attach-agent $n1 $tcp6$ns attach-agent $n3 $tcpsink6$ns connect $tcp6 $tcpsink6set tcp7 [new Agent/TCP]set tcpsink7 [new Agent/TCPSink]$ns attach-agent $n4 $tcp7$ns attach-agent $n1 $tcpsink7$ns connect $tcp7 $tcpsink7set tcp8 [new Agent/TCP]set tcpsink8 [new Agent/TCPSink]$ns attach-agent $n2 $tcp8$ns attach-agent $n1 $tcpsink8$ns connect $tcp8 $tcpsink8set tcp9 [new Agent/TCP]set tcpsink9 [new Agent/TCPSink]$ns attach-agent $n1 $tcp9$ns attach-agent $n0 $tcpsink9$ns connect $tcp9 $tcpsink9set cbr [new  Application/Traffic/CBR] set cbr1 [new  Application/Traffic/CBR] set cbr2 [new  Application/Traffic/CBR]set cbr3 [new  Application/Traffic/CBR]set cbr4 [new  Application/Traffic/CBR]set cbr5 [new  Application/Traffic/CBR]set cbr6 [new  Application/Traffic/CBR]set cbr7 [new  Application/Traffic/CBR]set cbr8 [new  Application/Traffic/CBR]set cbr9 [new  Application/Traffic/CBR]$cbr attach-agent $tcp$cbr1 attach-agent $tcp1$cbr2 attach-agent $tcp2$cbr3 attach-agent $tcp3$cbr4 attach-agent $tcp4$cbr5 attach-agent $tcp5$cbr6 attach-agent $tcp6$cbr7 attach-agent $tcp7$cbr8 attach-agent $tcp8$cbr9 attach-agent $tcp9 #Define a 'finish' procedure proc finish {} {     global ns tracefile namfile     $ns flush-trace     close $tracefile     close $namfile }$ns at 0.5 "$cbr start" $ns at 1.0 "$cbr stop"$ns at 1.0 "$cbr1 start" $ns at 1.5 "$cbr1 stop"$ns at 1.5 "$cbr2 start" $ns at 2.0 "$cbr2 stop"$ns at 2.0 "$cbr3 start" $ns at 2.5 "$cbr3 stop"$ns at 2.5 "$cbr4 start" $ns at 3.0 "$cbr4 stop"$ns at 3.5 "$cbr5 start" $ns at 4.0 "$cbr5 stop"$ns at 4.0 "$cbr6 start" $ns at 4.5 "$cbr6 stop"$ns at 5.0 "$cbr7 start" $ns at 5.5 "$cbr7 stop"$ns at 5.0 "$cbr8 start" $ns at 5.5 "$cbr8 stop"$ns at 5.5 "$cbr9 start" $ns at 6.0 "$cbr9 stop" $ns at $val(stop) "$ns nam-end-wireless $val(stop)" $ns at $val(stop) "finish" $ns at $val(stop) "puts \"done\" ; $ns halt" $ns run