Network Simulator 2: IntroductionPresented by Ke LiuDept. Of Computer ScienceSUNY BinghamtonSpring, 20061NS-2 Overviewc Ke Liu, SUNY-Binghamton, 20062NS-2• Developed by UC Berkeley• Maintained by USC• Popular simulator in scientific environment• Other popular network simulators– QualNet: based on GloMoSim– Others: GloMoSim, OPNET, etcc Ke Liu, SUNY-Binghamton, 20063NS2 Goals• To support networking research and education– Protocol design, traffic studies, etc.– Protocol comparison;– New architecture designs are also supported.• To provide collaborative environment– Freely distributed, open source;– Increase confidence in resultc Ke Liu, SUNY-Binghamton, 20064Two Languages: C++, OTclOTcl: short for MIT Object Tcl,an extension to Tcl/Tk for object-oriented programming.• Used to build the network structure and topologywhich is just the surface of your simulatoion;• Easily to configure your network parameters;• Not enough for research schemes and protocol architecture adaption.c Ke Liu, SUNY-Binghamton, 20065Two Languages (Con’t)C++: Most important and kernel part of the NS2• To implement the kernel of the architecture of the protocol designs;• From the packet flow view, the processes run on a single node;• To change or “comment out” the existing protocols running in NS2;• Details of your research scheme.c Ke Liu, SUNY-Binghamton, 20066Why 2 Languages?• 2 requirements of the simulator– Detailed simulation of Protocol: Run-time speed;– Varying parameters or configuration: easy to use.• C++ is fast to run but slower to code and change;• OTcl is easy to code but runs slowly.c Ke Liu, SUNY-Binghamton, 20067Protocols/Models supported by NS2• Wired Networking– Routing: Unicast, Multicast, and Hierarchical Routing, etc.– Transportation: TCP, UDP, others;– Traffic sources: web, ftp, telnet, cbr, etc.– Queuing disciplines: drop-tail, RED, etc.– QoS: IntServ and Diffserv Wireless Networking• Ad hoc routing and mobile IP– Routing Protocol: AODV, DSDV, DSR, etc.– MAC layer Protocol: TDMA, CDMA(?), IEEE Mac 802.x, etc.– Physical layers: different channels(?), directional attena• Sensor Networksc Ke Liu, SUNY-Binghamton, 20068Researches based on NS2• Intserv/Diffserv (QoS)• Multicast: Routing, Reliable multicast• Transport: TCP Congestion control• Application: Web caching Multimedia• Sensor Networks: LEACH, Directed Diffusion, etc.• etc.c Ke Liu, SUNY-Binghamton, 20069NS2 research actions• NS2: the simulator itself, now version: ns-2.29We will work with the part mostly.•NAM: Network animator. Visualized trace tool(not really).My recommendation is that ”Don’t use nam at all”.•Pre-processing:Traffic and topology generators•Post-processing:Simple trace analysis, often in Awk, Perl(mostly), or Tclc Ke Liu, SUNY-Binghamton, 200610Living under NS2c Ke Liu, SUNY-Binghamton, 200611The NS2 Directory Structurec Ke Liu, SUNY-Binghamton, 200612Warning• Try to avoid using ns2 with version before 2.27• DO NOT use gcc 4.x, suggestion: gcc3.3• If you work withMAC layer protocols, please be careful for the versionsc Ke Liu, SUNY-Binghamton, 200613A Simple SimulationWe just need one Tcl script to do so.c Ke Liu, SUNY-Binghamton, 200614A Simple Simulation, part 1: set up$ns_ use-scheduler Heap ;#Specify the scheduler, default: List Schedulerset ns [new Simulator] ;#Create a simulator object$ns color 1 Blue$ns color 2 Red;#Define different colors for data flows (for NAM)set nf [open out.nam w]$ns namtrace-all $nfset tf [open trace.tr w]$ns trace-all $tf;#Create trace files for simulationproc finish {} {global ns nf tf$ns flush-trace#Close the NAM trace fileclose $nf#Close the ns2 trace fileclose $tfexit 0};#Define a ’finish’ procedurec Ke Liu, SUNY-Binghamton, 200615A Simple Simulation, part 2: n/w structure#Create four nodesset n0 [$ns node]set n1 [$ns node]set n2 [$ns node]set n3 [$ns node]#Create links between the nodes$ns duplex-link $n0 $n2 2Mb 10ms DropTail$ns duplex-link $n1 $n2 2Mb 10ms DropTail$ns duplex-link $n2 $n3 1.7Mb 20ms DropTail#Set Queue Size of link (n2-n3) to 10$ns queue-limit $n2 $n3 10#Give node position (for NAM)$ns duplex-link-op $n0 $n2 orient right-down$ns duplex-link-op $n1 $n2 orient right-up$ns duplex-link-op $n2 $n3 orient right#Monitor the queue for link (n2-n3). (for NAM)$ns duplex-link-op $n2 $n3 queuePos 0.5c Ke Liu, SUNY-Binghamton, 200616A Simple Simulation, part 3: Transport and Traffic#Setup a TCP connection: from node 0 to node 3set tcp [new Agent/TCP]$ns attach-agent $n0 $tcpset sink [new Agent/TCPSink]$ns attach-agent $n3 $sink$ns connect $tcp $sink$tcp set fid_ 1#Setup a FTP over TCP connectionset ftp [new Application/FTP]$ftp attach-agent $tcp$ftp set type_ FTP ;#for Nam#Setup a UDP connection: from node 1 to node 3set udp [new Agent/UDP]$ns attach-agent $n1 $udpset null [new Agent/Null]$ns attach-agent $n3 $null$ns connect $udp $null$udp set fid_ 2c Ke Liu, SUNY-Binghamton, 200617A Simple Simulation, part 4: traffic#Setup a CBR over UDP connectionset cbr [new Application/Traffic/CBR]$cbr attach-agent $udp $cbrset type_ CBR $cbr ;#used by Namset packet_size_ 1000 $cbrset rate_ 1mb $cbrset random_ false ;#generating traffic periodically#Schedule events for the CBR and FTP agents$ns at 0.1 "$cbr start"$ns at 1.0 "$ftp start"$ns at 4.0 "$ftp stop"$ns at 4.5 "$cbr stop"#Detach tcp and sink agents (not really necessary)$ns at 4.5 "$ns detach-agent $n0 $tcp ; $ns detach-agent $n3 $sink"#Call the finish procedure after 5 seconds of simulation time$ns at 5.0 "finish"#Run the simulation$ns runc Ke Liu, SUNY-Binghamton, 200618Steps in writing a simulating script• Create the event scheduler• Turn on tracing• Create network• Setup routing• Insert errors• Create transport connection• Create traffic• Transmit application-level datac Ke Liu, SUNY-Binghamton, 200619The trace file• Turn on tracing on specific links$ns_ trace-queue $n0 $n1• Each line in the trace file is in the format:< event > < time > < f rom > < to > < pkt − type >< pkt − size > < flags > < f id > < src.port > < dst.port >< seq > < unique pkt id >• Trace example:+ 1 0 2 cbr 210 ------- 0 0.0 3.1 0 0- 1 0 2 cbr 210 ------- 0 0.0 3.1 0 0r 1.00234 0 2 cbr 210 ------- 0 0.0 3.1 0 0• Event: s send, r receive, + enqueue, − dequeue, d drop, f forward,c Ke Liu, SUNY-Binghamton, 200620The network Topologyc Ke Liu, SUNY-Binghamton,