NS-2 Tutorial

University of Texas at Arlington

CSE 5346/4346 High Performance Networks

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NS-2 TutorialNS-2 Tutorial

Choe, Hyun Jung (Stella)Choe, Hyun Jung (Stella) Spring 2008Spring 2008

High Performance NetworksHigh Performance NetworksDepartment of Computer Science and EngineeringDepartment of Computer Science and Engineering

The University of Texas at ArlingtonThe University of Texas at Arlington



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OutlineOutline

• NS-2 Overview

• How to Run NS-2

• How to Program

• Simulation Examples

• Project Overview

• Q & A


NS-2 OverviewNS-2 Overview



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What is NS-2?What is NS-2?

• VINT Project

- UC Berkeley, LBL, USC/ISI, and Xerox PARC

• Goals

- Support networking research and education

- Freely distributed, open source Share code, protocols, models, etc

• a Discrete Event Simulator

• Link layer and up

• Wired and Wireless



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NS ModelsNS Models

•Wired- Routing: DV, LS, PIM-SM etc.- Transportation: TCP and UDP- Traffic sources: web, ftp, telnet, cbr, stochastic

etc.- Queuing disciplines: drop-tail, RED, FQ, SFQ, DRR

etc.- QoS: IntServ and Diffserv …- Emulation

• Wireless- Ad hoc routing, mobile IP and Satellite- Directed diffusion, sensor-MAC



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NS ArchitectureNS Architecture

• Object-oriented (C++, OTcl)

• data / control separation- C++ for data:

per packet processing, core of ns

fast to run, detailed, complete control

- OTcl for control: Simulation scenario configurations

Periodic or triggered action

Manipulating existing C++ objects

fast to write and change



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OTcl and C++: The DualityOTcl and C++: The Duality

C++

otcl

C++/OTcl split objects Pure C++

objects

Pure OTclobjects

! OTcl (object variant of Tcl) and C++ share class hierarchy !



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NS ComponentsNS Components

- visualize ns (or other) outputPre-processing:- Traffic and topology generators

Post-processing:- simple trace analysis, often in Tcl, Awk or Perl


Part II: How to Run NS-2Part II: How to Run NS-2



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How to Run NS-2How to Run NS-2

① gamma2 server- Version: 2.30- Please use /tmp for your trace files (not codes)

(later)- xdisplay for graphical results

② If you want to install NS2 in your own PC- Current release: ns-2.31, Mar 10, 2007)

http://www.isi.edu/nsnam/ns/ns-build.html

- Platforms Most Unix and Linux Windows and Mac



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How to Setup PathHow to Setup Path

• ls –a• .cshrcsetenv LD_LIBRARY_PATH /opt/ns-allinone-2.30/…

• .bash_profileexport PATH=/opt/ns-allinone-2.30/bin:$PATHexport LD_LIBRARY_PATH=/opt/ns-allinone-2.30/otcl-1.12:/opt/ns-allinone-2.30/lib:$LD_LIBRARY_PATH

export TCL_LIBRARY=/opt/ns-allinone-2.30/tcl8.4.13/library



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gamma /tmp gamma /tmp

• for Temporary Usage only- Do Not save your scripts under /tmp

• Use Your Own directory- mkdir /tmp/your_dir/

• Exampleset nf [open /tmp/your_dir/out.nam w]



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How to Install NS-2 (Under How to Install NS-2 (Under Windows)Windows)• http://nsnam.isi.edu/nsnam/index.php/Running_Ns_a

nd_Nam_Under_Windows_9x/2000/XP_Using_Cygwin

• Cygwin-1.3.12 or later required Select “UNIX” text type to check current mode, type “mount | grep textmode” C:\Cygwin (not C:\Program Files\Cygwin) “Install” <X11> and <Devel> Categories (next page)

and others (e.g., vim) in <Editor> Download NS-2 under Cygwin (E.g., under /usr/local/)• tar zxvf ns-allinone-2.2x.x.tar.gz• cd ns-allinone-2.2x• ./install



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Error?Error?

• error near unexpected token `)'./configure: line 7624: ` OSF*)'tcl8.3.2 configuration failed! Exiting ...Tcl is not part of the ns project. Please see

www.Scriptics.comto see if they have a fix for your platform.

- Remove ‘ only if there are two ‘ at the end of relid

- find . | xargs -n 1 grep -H relid\‘

• Others-

http://ns-2.blogspot.com/2006/05/problem-in-installing-ns-2292-allinone.html

- http://www.isi.edu/nsnam/ns/ns-cygwin-old.html



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How to Use Cygwin-XHow to Use Cygwin-X

• http://xfree86.cygwin.com/docs/ug//usr/X11R6/

• Run /usr/X11R6/bin/startxwin.bat

• % sh /usr/X11R6/bin/startxwin.sh

• % cp /etc/X11/xinit/xinitrc ~/.xinitrc

• PATH=%PATH:/usr/X11R6/bin

• % startx &



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NS-2 Directory StructureNS-2 Directory Structure

TK8.4.13 OTcl tclclTcl8.4.13 ns-2 nam-1.12

tcl

ex test lib

...

...

examples validation tests

C++ code

OTcl code

ns-allinone

mcast

/opt/ns-allinone-2.30/

...


Part III: How to ProgramPart III: How to Program



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Basic Tcl ProgrammingBasic Tcl Programming

• set b 0- “b = 0” in C

• set x $b• set x [expr $a + $b]

• http://www-sop.inria.fr/maestro/personnel/Eitan.Altman/COURS-NS/n3.pdf

•



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Basic TclBasic Tcl

# Command arg1 arg2 arg3 …set a 43set b 27proc test { a b } {

set c [expr $a + $b]set d [expr [expr $a - $b] * $c]for {set k 0} {$k < 10} {incr k} {

if {$k < 5} { puts “k < 5, pow = [expr pow($d, $k)]” } else { puts “k >= 5, mod = [expr $d % $k]” } }}



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Elements of NS-2Elements of NS-2

• Create the event scheduler

• [Turn on tracing]

• Create network

• Setup routing

• Insert errors

• Create transport connection

• Create traffic

• Transmit application-level data



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How to SimulateHow to Simulate

•Create event scheduler- set ns [new Simulator]

• Schedule events- $ns at <time> <event>

<event>:any legitimate ns/tcl commands

- $ns at 5.0 “finish”

• Start scheduler- $ns run

• TclCL- C++ and OTcl linkage - glue library that makes it easy to share

functions, variables, etc

NS-2NS-2

Tcl

OTcl

TclCL

Event

Sch

edu

ler

Network Components

C/C++



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Example: Example: helloWorld.tclhelloWorld.tcl

set ns [new Simulator]

$ns at 1 “puts \“Hello World!\””

$ns at 1.5 “exit”

$ns run

% ns simple.tcl

Hello World!

%



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Creating NetworkCreating Network

• Nodes- set n0 [$ns node]- set n1 [$ns node]

• Links and queuing- $ns duplex-link $n0 $n1 <bandwidth> <delay>

<queue_type>- <queue_type>: DropTail, RED, CBQ, FQ, SFQ,

DRR- $ns duplex-link-op $no $n1 OPTIONS

n0 n1



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Setup RoutingSetup Routing

• Unicast- $ns rtproto <type>- <type>: Static, Session, DV, cost, multi-path

• Multicast- $ns multicast (right after [new Simulator])- $ns mrtproto <type>- <type>: CtrMcast, DM, ST, BST



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Creating Connection: UDPCreating Connection: UDP

• UDP- set udp [new Agent/UDP]

- set null [new Agent/Null]- $ns attach-agent $n0 $udp- $ns attach-agent $n1 $null- $ns connect $udp $null

n0 n1UDP null



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Creating Traffic: On Top of UDPCreating Traffic: On Top of UDP

• CBR- set src [new Application/Traffic/CBR]- $src attach-agent $udp0

• Exponential or Pareto on-off- set src [new Application/Traffic/Exponential]- set src [new Application/Traffic/Pareto]- $src attach-agent $udp0

n0 n1UDP null

CBR



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Structure of a Unicast NodeStructure of a Unicast Node



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Structure of a Simplex LinkStructure of a Simplex Link



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Creating Connection: TCPCreating Connection: TCP

• TCP- 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 n1TCP sink



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Creating Traffic: On Top of TCPCreating Traffic: On Top of TCP

• FTP- set ftp [new Application/FTP]- $ftp attach-agent $tcp

• Telnet- set telnet [new Application/Telnet]- $telnet attach-agent $tcp

n0 n1TCP sink

FTP



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A simulation exampleA simulation example

n0

n1

n2 n3

n4

n5

tcp

tcp

sink

sink

ftp

ftp

5Mb, 15ms10Mb,2ms 10Mb,2ms

W=32

W=32



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TCP AgentsTCP Agents

• ns has several variants of TCP available: - -- Agent/TCP/Tahoe a ``tahoe'' TCP sender - -- Agent/TCP/Reno a ``Reno'' TCP sender - -- Agent/TCP/NewReno Reno with a modification - -- Agent/TCP/Sack1 TCP with selective repeat (follows RFC2018) - -- Agent/TCP/Vegas TCP Vegas - -- Agent/TCP/Fack Reno TCP with ``forward acknowledge ment''

• The oneway TCP receiving agents currently supported are: - -- Agent/TCPSink TCP sink with one ACK per packet - -- Agent/TCPSink/DelAck TCP sink with configurable delay per ACK - -- Agent/TCPSink/Sack1 selective ACK sink (follows RFC2018) - -- Agent/TCPSink/Sack1/DelAck Sack1 with DelAck

• The twoway experimental sender currently supports only a Reno form of TCP: - -- Agent/TCP/FullTcp



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TCP Agent ParametersTCP Agent Parameters

• Agent/TCP set tcpTick— 0.1 ;# timer granularity in sec (.1 is NONST ANDARD)

• Agent/TCP set maxrto— 64 ;# bound on RTO (seconds) • Agent/TCP set dupacks— 0 ;# duplicate ACK counter

• Agent/TCP set ack— 0 ;# highest ACK received

• Agent/TCP set cwnd— 0 ;# congestion window (packets)

• Agent/TCP set awnd— 0 ;# averaged cwnd (experimental) • Agent/TCP set ssthresh— 0 ;# slowstat threshold (packets) • Agent/TCP set rtt— 0 ;# rtt sample

• Agent/TCP set srtt— 0 ;# smoothed (averaged) rtt • Agent/TCP set rttvar— 0 ;# mean deviation of rtt samples • Agent/TCP set backoff— 0 ;# current RTO backoff factor • Agent/TCP set maxseq— 0 ;# max (packet) seq number sent



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Tracing and Monitoring ITracing and Monitoring I

• Trace packets on all links • #Open the NAM trace file #Open the Trace file

- set nf [open out.nam w] set tf [open out.tr w]

- $ns namtrace-all $nf $ns trace-all $tf

• Must appear immediately after creating scheduler• Turn on tracing on specific links

- $ns trace-queue $n0 $n1- $ns namtrace-queue $n0 $n1

• Event tracing (support TCP right now)- Record “event” in trace file: $ns eventtrace-all



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Tracing and Monitoring IITracing and Monitoring II



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Tracing and Monitoring IIITracing and Monitoring III

• Queue monitor set qmon [$ns monitor-queue $n0 $n1 $q_f $sample_interval] - Get statistics for a queue

$qmon set pdrops_

- Record to trace file as an optional29.000000000000142 0 1 0.0 0.0 4 4 0 1160 1160 0

• Flow monitorset fmon [$ns_ makeflowmon Fid]$ns_ attach-fmon $slink $fmon$fmon set pdrops_



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Tracing and Monitoring IVTracing and Monitoring IV

• Variable tracing in namAgent/TCP set nam_tracevar_ true$tcp tracevar srtt_$tcp tracevar cwnd_

• Monitor agent variables in nam$ns add-agent-trace $tcp $tcp$ns add-agent-trace $tcp $tcp$ns monitor-agent-trace $tcp$ns monitor-agent-trace $tcp$srm0 tracevar cwnd_$srm0 tracevar cwnd_…………$ns delete-agent-trace $tcp$ns delete-agent-trace $tcp



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Visualization ToolsVisualization Tools

• nam-1 (Network AniMator Version 1)- Packet-level animation- Well supported by ns

• xgraph- Conversion from ns trace to xgraph format



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xgraphxgraph

• The xgraph program draws a graph on an X display given data read from either data files. - To run it: xgraph dataFileName

• You can save the hardcopy of the graph as a postscript file.

• Xgraph is available on gamma:

- /opt/ns-allinone-2.30/xgraph-12.1



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namnam

• Basic visualization- Topology layout- Animation control- Synchronous replay

• Fine-tune layout• TCP/SRM visualization• Editor: generate ns simulation scripts



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nsnsnam Interfacenam Interface

• Color• Node manipulation• Link manipulation• Topology layout• Protocol state• Misc



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nam Interface: Colornam Interface: Color

• Color mapping$ns color 1 red$ns color 1 red

$ns color 2 blue$ns color 2 blue

$ns color 3 chocolate$ns color 3 chocolate

• Color flow id association$tcp0 set fid_ 1$tcp0 set fid_ 1 ;# red packets;# red packets

$tcp1 set fid_ 2$tcp1 set fid_ 2 ;# blue packets;# blue packets



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nam Interface: Nodesnam Interface: Nodes

• Color$node color red$node color red

• Shape (can’t be changed after sim starts)$node shape box$node shape box ;# circle, box, hexagon;# circle, box, hexagon

• Marks (concentric “shapes”)$ns at 1.0 “$n0 add-mark m0 blue box”$ns at 1.0 “$n0 add-mark m0 blue box”

$ns at 2.0 “$n0 delete-mark m0”$ns at 2.0 “$n0 delete-mark m0”

• Label (single string)$ns at 1.1 “$n0 label \”web cache 0\””$ns at 1.1 “$n0 label \”web cache 0\””



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nam Interfaces: Linksnam Interfaces: Links

• Color$ns duplex-link-op $n0 $n1 color "green"$ns duplex-link-op $n0 $n1 color "green"

• Label$ns duplex-link-op $n0 $n1 label "abced"$ns duplex-link-op $n0 $n1 label "abced"

• Dynamics (automatically handled)$ns rtmodel Deterministic {2.0 0.9 0.1} $n0 $n1$ns rtmodel Deterministic {2.0 0.9 0.1} $n0 $n1

• Asymmetric links not allowed



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nam Interface: Topo Layoutnam Interface: Topo Layout

• “Manual” layout: specify everything

$ns duplex-link-op $n(0) $n(1) orient right$ns duplex-link-op $n(0) $n(1) orient right



$ns duplex-link-op $n(3) $n(4) orient 60deg$ns duplex-link-op $n(3) $n(4) orient 60deg

• If anything missing automatic layout



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nam Interface: Protocol Statenam Interface: Protocol State

• Monitor values of agent variables

$ns add-agent-trace $srm0 srm_agent0$ns add-agent-trace $srm0 srm_agent0

$ns monitor-agent-trace $srm0$ns monitor-agent-trace $srm0

$srm0 tracevar C1_$srm0 tracevar C1_

$srm0 tracevar C2_$srm0 tracevar C2_

# … …# … …

$ns delete-agent-trace $tcp1$ns delete-agent-trace $tcp1



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nam Interface: Miscnam Interface: Misc

• Annotation- Add textual explaination to your sim

$ns at 3.5 "$ns trace-annotate \“packet drop\"“$ns at 3.5 "$ns trace-annotate \“packet drop\"“

• Set animation rate

$ns at 0.0 "$ns set-animation-rate 0.1ms"$ns at 0.0 "$ns set-animation-rate 0.1ms"



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Summary: Generic Script StructureSummary: Generic Script Structure

set ns [new Simulator]set ns [new Simulator]

# [Turn on tracing]# [Turn on tracing]

# Create topology# Create topology

# Setup packet loss, link dynamics# Setup packet loss, link dynamics

# Create routing agents# Create routing agents

# Create: # Create:

# - multicast groups# - multicast groups

# - protocol agents# - protocol agents

# - application and/or setup traffic sources# - application and/or setup traffic sources

# Post-processing procs# Post-processing procs

# Start simulation# Start simulation

Documents

NS-2 Tutorial