Network Simulator 2 Tejas Vasavada

Contents Simulation of wired networks Simulation of wireless networks Traffic and movement-pattern files Trace files Analyzing trace files using 'awk' script 'gnuplot' – utility to plot graphs

Contents (contd.) DSR – A protocol for MANETs Source code of DSR in NS2 How to change DSR (with examples) Printing packet header Configuring nodes to drop packets Adding a new function in DSR Calling previous function from Tcl Passing arguments from Tcl to DSR Use of timers

Contents How to add new package in NS Simulation of Wired-cum-Wireless Networks

Introduction Simulation comes before implementation. A newly designed protocol is simulated first to test the performance.

Simulation Tools OmNet++, NS2, Qualnet, Opnet, GlomoSim etc. NS2 - an open source tool, widely used in academics for research purpose.

How to use NS2 Front end – Tcl (Tool Command Langauage) Back end – C++ Today we will learn Tcl.

Wired Network

Tcl script set ns [new Simulator] creates an instance of ‘Simulator’ class. Output is stored in .nam files (Network AniMator) set nf [open out.nam w] $ns namtrace-all $nf

Tcl script (contd.) proc finish {} { global ns nf $ns flush-trace close $nf exec nam out.nam & exit 0 } ‘finish’ will be called at the end of simulation.

Tcl Script (contd.) $ns at 5.0 "finish“ finish() is called at 5th second. $ns run Starts simulation.

Tcl script (contd.) set n0 [$ns node] set n1 [$ns node] Creates two nodes - n0 and n1. $ns duplex-link $n0 $n1 1Mb 10ms DropTail Connects both the nodes.

Tcl script (contd.) #Create a UDP agent and attach it to node n0 set udp0 [new Agent/UDP] $ns attach-agent $n0 $udp0 # Create a CBR traffic source and attach it to udp0 set cbr0 [new Application/Traffic/CBR] $cbr0 set packetSize_ 500 $cbr0 set interval_ 0.005 $cbr0 attach-agent $udp0

Tcl script (contd.) set null0 [new Agent/Null] $ns attach-agent $n1 $null0 Creates a null agent and attaches it to n1. $ns connect $udp0 $null0 Two agents are connected togother.

Tcl script (contd.) $ns at 0.5 "$cbr0 start" $ns at 4.5 "$cbr0 stop“ Node n0 will start sending packets at time 0.5 sec and will stop at 4.5 sec.

Exercise 1 Read example1.tcl provided to you. Run it using following command ns example1.tcl Read & Run Example2.tcl

Example2.tcl $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 Creates star shape topology.

Example2.tcl (contd.)

Example2.tcl (contd.) Nodes n0 and n1 connect to n3 via n2. Bandwidth n2-n3 < (bandwidth n0-n2 + bandwidth n1-n2) Node n2 drops packets.

Example2.tcl To see what is happening at n2, different flows should be coloured differently. $udp0 set class_ 1 $udp1 set class_ 2 $ns color 1 Blue $ns color 2 Red

Example2.tcl (contd.)

Example3.tcl for {set i 0} {$i < 7} {incr i} { set n($i) [$ns node] Creates 7 nodes. $ns duplex-link $n($i) $n([expr ($i+1)%7]) 1Mb 10ms DropTail

Example3.tcl (contd.)

Example3.tcl (contd.) Node n0 is connected to n3. Packets will pass through n1 and n2 (shortest path). Break n1-n2 link using following commands. $ns rtmodel-at 1.0 down $n(1) $n(2) $ns rtmodel-at 2.0 up $n(1) $n(2)

Example3.tcl (contd.)

Example3.tcl (contd.) Use following command to use alternate path. $ns rtproto DV

Example3.tcl (contd.)

Wireless Network

Simple-wireless.tcl Components of a mobile node… Link Layer, Interface Queue between LL and Network Layer, MAC Layer Routing Layer Parameters of a mobile node Type of antenna, Radio propagation model

Simple-wireless.tcl (contd.) set val(chan) Channel/WirelessChannel ;# channel type set val(prop) Propagation/TwoRayGround ;# radio-propagation model set val(ant) Antenna/OmniAntenna ;# Antenna type set val(ll) LL ;# Link layer type set val(ifq) Queue/DropTail/PriQueue ;# Interface queue type set val(ifqlen) 50 ;# max packet in ifq set val(netif) Phy/WirelessPhy ;# network interface type set val(mac) Mac/802_11 ;# MAC type set val(rp) DSDV ;# ad-hoc routing protocol set val(nn) 2 ;# number of mobilenodes

Simple-wireless.tcl (contd.) set ns_ [new Simulator] Creates new instance of ‘Simulator’. set tracefd [open simple.tr w] $ns_ trace-all $tracefd Creates new instance of trace file.

Simple-wireless.tcl (contd.) set topo [new Topography] Creates new topology. $topo load_flatgrid 500 500 Sets resolution of topology to 500 x 500.

Simple-wireless.tcl (contd.) # Configure nodes $ns_ node-config -adhocRouting $val(rp) -llType $val(ll) \ -macType $val(mac) ifqType $val(ifq) \ -ifqLen $val(ifqlen) -antType $val(ant) \ -propType $val(prop) –phyType $val(netif) \ -topoInstance $topo \ -channelType $val(chan) \ -agentTrace ON \ -routerTrace ON \ -macTrace OFF \ -movementTrace OFF

Simple-wireless.tcl (contd.) for {set i 0} {$i < $val(nn) } {incr i} { set node_($i) [$ns_ node ] $node_($i) random-motion 0 } Random motion is disabled. We will provide initial position and movement parameters.

Simple-wireless.tcl (contd.) $node_(0) set X_ 5.0 $node_(0) set Y_ 2.0 $node_(0) set Z_ 0.0 $node_(1) set X_ 390.0 $node_(1) set Y_ 385.0 $node_(1) set Z_ 0.0

Simple-wireless.tcl (contd.) # Node_(1) starts to move towards node_(0) $ns_ at 50.0 "$node_(1) setdest 25.0 20.0 15.0" $ns_ at 10.0 "$node_(0) setdest 20.0 18.0 1.0“ # Node_(1) then starts to move away from node_(0) $ns_ at 100.0 "$node_(1) setdest 490.0 480.0 15.0"

Simple-wireless.tcl (contd.) # TCP connections between node_(0) and node_(1) set tcp [new Agent/TCP] $tcp set class_ 2 set sink [new Agent/TCPSink] $ns_ attach-agent $node_(0) $tcp $ns_ attach-agent $node_(1) $sink $ns_ connect $tcp $sink set ftp [new Application/FTP] $ftp attach-agent $tcp $ns_ at 10.0 "$ftp start"

Simple-wireless.tcl (contd.) # Tell nodes when the simulation ends for {set i 0} {$i < $val(nn) } {incr i} { $ns_ at 150.0 "$node_($i) reset"; } $ns_ at 150.0001 "stop" $ns_ at 150.0002 "puts \"NS EXITING...\" ; $ns_ halt" proc stop {} { global ns_ tracefd close $tracefd

Simple-wireless.tcl (contd.) puts "Starting Simulation..." $ns_ run Prints the message and starts simulation.

Traffic-pattern file and movement-pattern file

Wireless-1.tcl set val(cp) “/root/cbr-3-test" set val(sc) “/root/scen-3-test“ cbr-3-test is connection-pattern file. scen-3-test is movement-pattern file.

Wireless-1.tcl (contd.) set val(x) 670 set val(y) 670 set namtrace [open wireless1-out.nam w] $ns_ namtrace-all-wireless $namtrace $val(x) $val(y)

Wireless-1.tcl (contd.) puts "Loading connection pattern..." source $val(cp) Loads connection-pattern file. puts "Loading scenario file..." source $val(sc) Loads movement-pattern(scenario) file.

Wireless-1.tcl (contd.) for {set i 0} {$i < $val(nn)} {incr i} { $ns_ initial_node_pos $node_($i) 20 } Defines size of node in nam

Traffic pattern file ns cbrgen.tcl [-type cbr|tcp] [-nn nodes] [-seed seed] [-mc connections] [-rate rate] > [filenm] Generates a traffic pattern. It is saved in file ‘filenm’. -type : type of connection cbr or tcp -nn : no. of nodes -seed : seed value used by random number generator -mc : no. of connections -rate : rate at with packets are sent

Traffic pattern file (contd.) ns cbrgen.tcl -type cbr -nn 10 -seed 1.0 -mc 8 -rate 4.0 > cbr-10-test Generates traffic-pattern and saves in file cbr-10-test. Create traffice-pattern file for tcp traffic and check how it differs from cbr-10-test

Movement-pattern file ‘setdest’ utility available at: ns-x.xx/indep-utils/cmu-scen-gen/setdest /setdest –v 1 –n <nodes> -p <pause time> -M <max speed> -t <sim time> -x <maxx> -y <maxy>

Movement-pattern file (contd.) ./setdest –v 2 –n <nodes> -s <speed type> -m <min speed> -M <max speed> -t <sim time> -P <pause type> -p <pause time> -x <maxx> -y <maxy> Speed type: 1 - uniform speed 2 - normal speed

Pause type: 1 - constant 2 – uniform [ 0, 2 x pause ] For e.g. ./setdest –v 2 -n 50 -s 1 -m 1 -M 20 -t 200 -P 1 -p 0 -x 200 -y 200 > /root/Desktop/scen-3-test

Trace file format

Trace files Output of simulation is in trace format. Trace file has two formats: old and new To use new format add following line in tcl script before calling trace-all . $ns use-newtrace

Trace file format Event type s send d drop r receive f forward Time -t

Trace file format (contd.) Node property tag -Ni Node id -Nx Node’s x-coordinate -Ny Node’s y-coordinate -Nz Node’s z-coordinate -Ne Node’s energy level -Nl Trace level (AGT, RTR, MAC)

Trace file format (contd.) -Is source address.source port number -Id dest address.dest port number -It packet type -Il packet size -If flow id -Ii unique id -Iv ttl value

Trace file format (contd.) Next hop information -Hs id for this node -Hd id of next node towards destination

Awk script

Awk script ‘Awk’ is a scripting language used to process text files. Processes the file row by row. Columns are identified like $1,$2 etc. awk –f <.awk file> <.tr> file. Use the awk file provided to calculate throughput from tracefile.

Sample Script - dr.awk BEGIN { sent=0 recd=0 }

dr.awk event=$1 level=$19 if(event == “s” && level == “AGT”) sent++ if(event == “r” && level == “AGT”) recd++ }

dr.awk END { printf("sent %g, recd %g, fwd %g, del. %g\n",sent,recd,fwd,recd/sent); }

GnuPlot

'gnuplot' Syntax: gnuplot <file.gnu> Read dr.gnu file to understand use of 'gnuplot' to plot graphs.

Adding new Files in NS Find ns2_ricean_dist folder available with this presentation. Follow the procedure in “README” file.