Network Simulation and Testing-ns-2 Tutorial

Network Simulation and Testing

Polly Huang EE NTU

ns-2 Tutorial

Tutorial Overview

• Welcome

• Gratitude

• Audience background

Tutorial Intensity

• Intended audience

– try to cover a wide range

– researchers, developers, educators

• Cover

– both API & internal

Schedule: 1

Week

2.20-3.10 overview/intro/essential/getting started 3.30-4.20 tcl/otcl/ns-2 fundamentals

4.30-5.20 examples - TCP, RED, multicast, web, wireless

Schedule: 2

Week

2.20-3.10 lab 1 setup/running examples 3.30-4.20 lab 2 tcl/otcl exercises

Schedule: 3

Week

2.20-3.10 wired internal 3.30-4.20 wireless internal

4.30-5.20 extending ns-2/making changes/case studies

Schedule: 4

Week

2.20-3.10 lab 4 intermediate ns-2 exercise 3.30-4.20 lab 5 getting data you want

Outline: Today

• Introduction

– the project, the software, the philosophy – software architecture

– installation and getting started

• tcl/otcl/ns-2 fundamentals

– programming tcl/otcl

The VINT Project

• Virtual InterNet Testbed

– a common platform for network research

– focus on multi-protocol interactions and scale – http://www.isi.edu/nsnam/vint/index.html

• Follow-up projects

Multi-state collaboration

• USC/ISI

• ACIRI

• UC Berkeley

• CMU

VINT People

• Project leads and co-PIs

– Lee Breslau (AT&T Labs-Research) – Deborah Estrin (UCLA)

– Kevin Fall (INTEL Research) – Sally Floyd (AT&T/ACIRI) – Mark Handley (AT&T/ACIRI) – John Heidemann (USC/ISI)

Project Goal

• To support

collaborative

simulation effort

– promote sharing

• incorporate recent simulation models

– increase confidence in results

• establish regression test suite

ns-2

• Discrete event simulator

• Packet level

• Link layer and up

• Wired and wireless

Development Status

• Columbia NEST

• UCB REAL

• ns-1

• ns-2 (as of 2001…)

Usage and Releases

• Users from approximately

– 600+ institutes – 50+ countries

• Releases

– periodic official releases

– nightly snapshots (probably compiles and works, but buyers beware)

Platforms

• Most UNIX and UNIX-like systems

 FreeBSD or *BSD  Linux

 Sun Solaris  HP, SGI

First Words of Caution

• While we have considerable confidence in

ns, ns is

not a polished

and finished

product, but the result of an ongoing effort

of research and development. In particular,

bugs in the software are still being

Second Words of Caution

• Users of ns are responsible for verifying for

themselves that their simulations are not

invalidated by

bugs

. We are working to

help the users with this by significantly

expanding and automating the validation

tests and demos.

Third Words of Caution

• Similarly, users are responsible for

verifying for themselves that their

simulations are not invalidated because the

model

implemented in the simulator is not

the model that they were expecting. The

ongoing ns Notes and Documentation

Tutorial Goals

• Caution to be taken

• Existing capability

• Design and implementation

• Extendibility

Outline: Today

• Introduction

– the project, the software, the philosophy

– software architecture

– installation and getting started

• tcl/otcl/ns-2 fundamentals

– programming tcl/otcl

Object-Oriented

+ Reusability

+ Maintainability

– Careful planning ahead

– Performance

C++ and otcl Separation

• C++ for data

– per packet action

• otcl for control

– periodic or triggered action

+ Compromize between composibility and

speed

otcl and C++: The Duality

C++

tcl Interpreter With Extents

• otcl: object-oriented support • tclcl: C++ and otcl linkage

tcl otcl tclcl ns-2 Event Scheduler N etw or k C om po ne nt

Installation

• Getting the pieces

– (tcl/tk8.4.5), otcl, tclcl, ns-2, (and nam-1)

• http://www.isi.edu/nsnam/ns/

• [email protected]

– [email protected]

Hello World - Interactive Mode

swallow 71% ns

% set ns [new Simulator]

_o3

% $ns at 1 “puts \“Hello World!\””

1

% $ns at 1.5 “exit”

2

Hello World - Passive Mode

simple.tcl

set ns [new Simulator]

$ns at 1 “puts \“Hello World!\”” $ns at 1.5 “exit”

$ns run

Outline: Today

• Introduction

– the project, the software, the philosophy – software architecture

– installation and getting started

• tcl/otcl/ns-2 fundamentals

– programming tcl/otcl

Fundamentals

• tcl

• otcl

• ns-2

Basic tcl

proc test {} { set a 43 set b 27

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]”

Basic otcl

Class mom

mom instproc init {age} { $self instvar age_ set age_ $age

}

mom instproc greet {} { $self instvar age_

Class kid -superclass mom

kid instproc greet {} { $self instvar age_

puts “$age_ years old kid:

What’s up, dude?” }

set a [new mom 45] set b [new kid 15]

Basic ns-2

• Creating the event scheduler

• [Tracing]

• Creating network

• Computing routes

• Creating connection

• Creating traffic

Creating Event Scheduler

• Create scheduler

– set ns [new Simulator]

• Schedule event

– $ns at <time> <event>

Tracing

• Trace packets on all links

– $ns trace-all [open test.out w]

<event> <time> <from> <to> <pkt> <size>--<flowid> <src> <dst> <seqno> <aseqno> + 1 0 2 cbr 210 --- 0 0.0 3.1 0 0

- 1 0 2 cbr 210 --- 0 0.0 3.1 0 0

r 1.00234 0 2 cbr 210 --- 0 0.0 3.1 0 0

• Trace packets on all links in nam-1 format

Creating Network

• Nodes

– set n0 [$ns node] – set n1 [$ns node]

• Links & Queuing

– $ns duplex-link $n0 $n1 <bandwidth> <delay> <queue_type>

Tracing Specific links

• $ns trace-queue $n0 $n1

Creating Network: LAN

• LAN

– $ns make-lan <node_list> <bandwidth>

<delay> <ll_type> <ifq_type> <mac_type> <channel_type>

– <ll_type>: LL

Computing routes

• Unicast

– $ns rtproto <type>

Creating 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

Creating 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

Creating Traffic: On Top of TCP

• FTP

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

– $ns at <time> “$ftp start”

• Telnet

Creating Traffic: On Top of UDP

• CBR

– set src [new Application/Traffic/CBR]

• Exponential or Pareto on-off

– set src [new Application/Traffic/Exponential] – set src [new Application/Traffic/Pareto]

Creating Traffic: Trace Driven

• Trace driven

– set tfile [new Tracefile] – $tfile filename <file>

– set src [new Application/Traffic/Trace] – $src attach-tracefile $tfile

Inserting Errors

• Creating Error Module

– set loss_module [new ErrorModel] – $loss_module set rate_ 0.01

– $loss_module unit pkt

– $loss_module ranvar [new RandomVariable/Uniform]

Network Dynamics

• Link failures

– route changes reflected automatically – can emulate node failure

Four Models

• $ns rtmodel-at <time> <up|down> $n0 $n1

• $ns rtmodel Trace <config_file> $n0 $n1

• $ns rtmodel <model> <params> $n0 $n1

• <model>: Deterministic, Exponential

• <params>: [<start>] <up_interval>

<down_interval> [<finish>]

Outlines

• Essentials

• Getting Started

• Fundamental tcl, otcl and ns-2

Case Studies

• TCP (tcp.tcl)

• Web (web.tcl & dumbbell.tcl)

• Queuing - RED (red.tcl)

Visualization Tools

• nam-1 (Network AniMator Version 1)

• xgraph

Basic ns-2: Special Topics

• multicast support

• application-level support

• wireless support

Multicast - 5 components

• enable multicast capability

• configure multicast routing

• create a multicast group/sender

• create a multicast receiver

Enabling multicast capability

• set ns [new Simulator -multicast on]

• or $ns multicast (right after [new

Configuring multicast routing

• $ns mrtproto <type>

Creating a multicast group

• set udp [new Agent/UDP]

• $ns attach-agent $n0 $udp

• set group [Node allocaddr]

• $udp set dst_addr_ $group

Creating a multicast receiver

• set rcvr [new Agent/NULL]

• $ns attach-agent $n1 $rcvr

• $ns at <time> “$n1 join-group $rcvr

$group”

Attaching a traffic source

• set cbr [new Application/Traffic/CBR]

• $cbr attach-agent $udp

Application - 2 components

• two-way TCP

Application: Two-way TCP

• FullTcp connection

– set tcp1 [new Agent/TCP/FullTcp] – set tcp2 [new Agent/TCP/FullTcp] – $ns attach-agent $n1 $tcp1

– $ns attach-agent $n2 $tcp2 – $ns connect $tcp1 $tcp2

Application: TcpApp

• User data transfer

– set app1 [new Application/TcpApp $tcp1] – set app2 [new Application/TcpApp $tcp2] – $app1 connect $app2

– $ns at 1.0 “$app1 send <data_byte> \”<ns-2 command>\””

Wireless - 5 components

• setup

• node configuration

– layer 3-2, layer 1, tracing, energy

• node coordinates

• node movements

• nam tracing

Setup

• set ns [new Simulator]

• set topo [new Topography]

Node Configuration: Layer 3-2

• $ns node-config

– adhocRouting <adhoc routing type> – llType LL

– ifqType Queue/DropTail/PriQueue – ifqLen <queue length>

– macType Mac/802_11

Node Configuring: Layer 1

– phyType Phy/WirelessPhy

– antType Antenna/OmniAntenna – propType <propagation model>

– channelType Channel/WirelessChannel – topoInstance $topo

Node Configuration: Tracing

• $ns node-config

– agentTrace <ON or OFF> – routerTrace <ON or OFF> – macTrace <ON or OFF>

Node Configuration: Energy

• $ns node-config

– energyModel EnergyModel – initialEnergy <total energy> – txPower <energy to transmit> – rxPower <energy to receive>

Creating Nodes

Node Coordinates

• $mnode set X_ <x>

• $mnode set Y_ <y>

• $mnode set Z_ 0

Node Movement

• Disable random motion

– $mnode random-motion 0

• Specified

– $ns at 1.0 “$mnode setdest <x> <y> <speed>”

• Random

Tracing

• at the beginning

– $ns namtrace-all-wireless [open test.nam w] <length> <width>

• initialize nodes

Case Studies

• multicast (mcast.tcl)

Basic ns-2: Not Covered

• mobile IP

• satellite

• DiffServ

• emulation

Next Week

• Bring your laptop

• Local FreeBSD

– Xwindows and network

• Remote FreeBSD