A Tutorial on Network A Tutorial on Network A Tutorial on Network A Tutorial on Network Simulator Simulator Simulator Simulator ---- nsnsnsns----2222

Oct, 2001Wendy Huang ( wendy@totoro.cs.nthu.edu.tw )

Anthony Liu ( perp@cs.nthu.edu.tw )

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Contents

1.Ns-2 Components2.Ns-2 Installation3.Objects4.The Language

5.Ns-2 by Examples6.References

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1.Ns-2 Components

Tcl/TkotclTclCL (formerly known as libTcl) ns-2nam-1 (optional) xgraph (optional)perl (optional)

Though some are optional, we suggest you install all-in-onepackage. Also, though ns2 is available for Windows platforms, we do not suggest because it’s tricky to install and use it on those platforms.

Though some are optional, we suggest you install all-in-onepackage. Also, though ns2 is available for Windows platforms, we do not suggest because it’s tricky to install and use it on those platforms.

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1.Ns-2 Components (Cont.)

tcl-debug (optional)dmalloc (optional)sgb2ns conversion program (optional)tiers2ns conversion program(optional)Cweb and sgb source code (optional)

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1.Ns-2 Components (Cont.)

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1.Ns-2 Components (Cont.)

To provide components better performance, C++ and OTcl are glued together.

To provide components better performance, C++ and OTcl are glued together.

The compound architecture of ns2The compound architecture of ns2

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2.Ns-2 Installation

Get the all-in-one package from website:http://www.isi.edu/nsnam/dist/ns-allinone-2.1b8a.tar.gz

Untar with the following command on Unix like platforms:tar zxf ns-allinone-2.1b8a.tar.gz

Move directory ns-2.1b8a to a place with enough space (Requires 200MB)

Build with:cd ns-2.1b8a ; ./install The 200MB requirement does

not include source tar ball.The 200MB requirement does not include source tar ball.

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2.Ns-2 Installation (Cont.)

After compilation, validation is also needed.For any problem or troubleshooting, please contact your nearest computer freak classmates. ☺

You might need to configure your environment variables to accommodate ns-2 execution requirements.

You might need to configure your environment variables to accommodate ns-2 execution requirements.

Ns-2 is installed on CS workstations!!! Further info required by T.A.’s.

Ns-2 is installed on CS workstations!!! Further info required by T.A.’s.

Validation would not pass on Linux with CLE. RedHat7.1 English version is successfully validated.

Validation would not pass on Linux with CLE. RedHat7.1 English version is successfully validated.

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3.Objects

SimulatorNodesLinksAgentsTraffics

The objects are interconnected by using member functions to attach each other.

The Simulator is an exceptions, which is a container object

The objects are interconnected by using member functions to attach each other.

The Simulator is an exceptions, which is a container object

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3.Objects (Cont.)

The relationship between objects of ns-2 can be uncovered from this figure.

The relationship between objects of ns-2 can be uncovered from this figure. I’ll be back.I’ll be back.

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3.Objects (Cont.)

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4.The Language

OTclNo declaration needed in advanceVariables declared as usedVariables referred with $ as prefixObject creation: [new CLASS_NAME]Comments starting with #

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4.1 Language Basics

Variables referred with $ as prefixVariables referred with $ as prefix

Procedure SupportedProcedure Supported

No declaration needed in advanceNo declaration needed in advance

Variables declared as usedVariables declared as used

Comments with #Comments with #

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4.1 Language Basics (Cont.)

Object creation: [new CLASS_NAME]Object creation: [new CLASS_NAME]

Instproc Member functionInstproc Member function

Inherit with -superclassInherit with -superclass

Class defines a classClass defines a class

Self reference with $selfSelf reference with $self

puts message outputs message out

Classwide variable with instvarClasswide variable with instvar

Calling member function Calling member function

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4.2 Total Recall

Variables (declarations, references)

Class (declarations, references, member functions , self reference, classwide variables)

Objects (Create, calling a member function, )

I still have no idea about syntax !!! (Have you ever heard two functions called copy and paste?)

Piece of Cake? (Cheese flavor please)

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5.Ns-2 by Examples

Ex: Two Nodes with trafficEx: XGraph example (graph only)EX: XGraph plus Nam (graph only)

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5.1 Ex1 Sourceset ns [new Simulator]

set nf [open ex1.nam w]

$ns namtrace-all $nf

proc finish {} {global ns nf

$ns flush-traceclose $nfexec nam ex1.nam &exit 0

}

# Create two nodes: 0, 1set n0 [$ns node]set n1 [$ns node]

# Connect $n0 and $n1$ns duplex-link $n0 $n1 1Mb 10ms DropTail

# Create a UDP agent and attach# it to node n0set udp0 [new Agent/UDP]$ns attach-agent $n0 $udp0

# Create a CBR traffic source# and attach it to udp0set cbr0 [new Application/Traffic/CBR]$cbr0 set packetSize_ 500$cbr0 set interval_ 0.005$cbr0 attach-agent $udp0

# Create a Null agent which acts # as traffic sink and attach it to node n1set null0 [new Agent/Null]$ns attach-agent $n1 $null0# Now the two agents have to # be connected with each other$ns connect $udp0 $null0

# Timer bound is 5 seconds.$ns at 5.0 "finish"

# Start Simulation$ns at 0.5 "$cbr0 start"$ns at 4.5 "$cbr0 stop"

$ns run

Save this file as ex1.tcl, run ‘ns ex1.tcl’ on X Window, you will see.

Save this file as ex1.tcl, run ‘ns ex1.tcl’ on X Window, you will see.

Two Nodes with traffic

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Ex 1 Screen Shot A single nam console occurs after the execution. And an animation window occurs for the ex1.tcl, click the play and adjust the step, see what happends!

A single nam console occurs after the execution. And an animation window occurs for the ex1.tcl, click the play and adjust the step, see what happends!

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More Screen Shot

One nam console instance with 2 nam animator instances (can be more, of course.)

One nam console instance with 2 nam animator instances (can be more, of course.)

Multiple Nam Instances

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5.2 XGraph example

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XG

raph

plus

Nam

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6.ReferencesNs-2 Homesite: � http://www.isi.edu/nsnam/ns/

OTcl Tutorials:� MIT Version: ftp://ftp.tns.lcs.mit.edu/pub/otcl/README.html� Berkeley Version: http://bmrc.berkeley.edu/research/cmt/cmtdoc/otcl

Ns-2 By Examples: � http://nile.wpi.edu/NS/

Ns-2 Tutorial (By Marc Gresis): � http://www.isi.edu/nsnam/ns/tutorial/index.html

Ns-2 Manual: � http://www.isi.edu/nsnam/ns/doc/index.html