Ns 2 Network Simulator An Introduction

1. Ns-2 Network Simulator An Introduction

6. Event Driven Simulation Event Queue Simulation Finished! TX Pkt Event @ 1.5sec Node 1 Module Node 2 Module TX Pkt Event @ 1.5sec RX Pkt Event @ 1.7sec RX Pkt Event @ 1.7sec TX Ack Event @ 1.8sec TX Ack Event @ 1.8sec RX Ack Event @ 2.0sec RX Ack Event @ 2.0sec

7. Simplified User’s View of NS-2

17. Example 1: TCP (FTP from n0 to n1) set ns [new Simulator] #Create 2 nodes set n0 [$ns node] set n1 [$ns node] set ftp [new Application/FTP] $ftp attach-agent $tcp $ns at 0.2 "$ftp start" $ns at 1.2 ”exit" $ns run $ns duplex-link $n0 $n1 1Mb 10ms DropTail set tcp [new Agent/TCP] set tcpsink [new Agent/TCPSink] $ns attach-agent $n0 $tcp $ns attach-agent $n1 $tcpsink $ns connect $tcp $tcpsink n0 n1

19. Screenshots

22. Example 1 (contd.) – Basic tracing #Create a simulator object set ns [new Simulator] #Open the nam trace file set nf [open out.nam w] # Start tracing $ns namtrace-all $nf #Open the general trace file set tf [open out.tr w] # Start tracing $ns trace-all $tf #Define a 'finish' procedure proc finish {} { global ns nf tf $ns flush-trace #Close the trace files close $nf close $tf #Execute nam on the trace file exec nam out.nam & exit 0 } # Say when to stop simulation $ns at 5.0 "finish“ #Run the simulation $ns run