Introducción a NS2

UNIVERSIDAD DISTRITAL FRANCISCO JOSE DE CALDAS

FACULTAD DE INGENIERÍA

Agenda

Introducción al NS2 Introducción al TCL, variables,

procedimientos, llamado a otros programas, Comandos de TCL

Estructura de una simulación en NS2, Scripts de simulación

Network AniMator Construcción de nodos, wireless nodes,

configuración, variables globales de NS2 Análisis de archivos de Trace de NS2

NS2, Network Simulator

A discrete event simulator

Developed for networking research

Focused on modeling network protocols

Not a finished product

NS Goals

Support networking research and education Protocol design, traffic studies, etc.

Provide a collaborative environment Freely distributed, open source

Share code, protocols, models, etc.

Allow easy comparison of similar protocols Increase confidence in results

Multiple levels of detail in one simulator

NS functionalities Wired world

Routing Protocols Transport Protocols Traffic sources: HTTP, FTP, Telnet, CBR Queuing disciplines QoS Models: IntServ and Diffserv

Wireless Ad hoc routing and mobile IP Sensor-MAC

Tracing, visualization, various utilities

NS Components

NS, the simulator itself NAM, the network animator

Visualize NS (or other) output NAM editor: GUI interface

Pre-processing: Traffic and topology generators

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

Installation, resources

Download ns fromhttp://www.isi.edu/nsnam/ns/ns-build.html

Installation problems and bug fixeshttp://www.isi.edu/nsnam/ns/ns-problems.html

ns mailing list: ns-users@isi.edu ns manual

http://www.isi.edu/nsnam/ns/ns-documentation.html ns-nam search site:

http://www.isi.edu/nsnam/htdig/search.html

TCL

Lenguaje de Script, orientado a la configuración de las entidades de la simulación.

set ns [new Simulator]

set n0 [$ns node]set n1 [$ns node]$ns duplex-link $n0 $n1 1Mb 10ms DropTail

set udp0 [new Agent/UDP]$ns attach-agent $n0 $udp0

set cbr0 [new Application/Traffic/CBR]$cbr0 set packetSize_ 500$cbr0 set interval_ 0.001$cbr0 attach-agent $udp0

set null0 [new Agent/Null]$ns attach-agent $n1 $null0$ns connect $udp0 $null0

$ns at 5.0 "finish"$ns at 0.5 "$cbr0 start"$ns at 4.99 "$cbr0 stop"$ns run

TCL

Declaración y utilización de variables

Store a random number in the variable r: set r [expr rand()] set a 10 set b 20 set c [expr $a + $b]

Usando NS

Problem

Simulationmodel

Setup/run simulation

with ns

Resultanalysis

Modifyns

Estructura de una simulación

Definición de parámetros, configuración general.

Definición de procedimientos varios. Definición de entidades, topología. Programación de eventos. Ejecución de la simulación.

Creación de nodos en el NS2$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 ON \-movementTrace OFF

#Create nodesfor {set i 0} {$i < $val(nn) } {incr i} {

set node_($i) [$ns node ]}

Dentro de los Scripts analizados, se ejecutaron comandos como los siguientes.

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

set val(chan) Channel/WirelessChannel; set val(prop) Propagation/TwoRayGround; set val(ant) Antenna/OmniAntenna ; set val(ll) LL ; set val(ifq) CMUPriQueue ;set val(ifqlen) 50 ; set val(netif) Phy/WirelessPhy ;

set val(mac) Mac/802_11 ; set val(rp) DSR ;set val(nn) 2 ;

Wireless Internals

Mobilenode Basic node that has address and port de-

muxes, routing agent etc Stack of network components consisting

of LL, MAC, NetIF radio-model etc Wireless channel

Mobile Node: Components

Link Layer Same as LAN, but with a separate ARP module Sends queries to ARP

ARP Resolves IP address to hardware (MAC) address Broadcasts ARP query

Interface queue Gives priority to routing protocol packets Has packet filtering capacity

Mobile Node: Components

MAC 802.11

IEEE RTS/CTS/DATA/ACK for unicast Sends DATA directly for broadcast

Network interface (PHY) Used by mobilenode to access channel Stamps outgoing packets with meta-data Interface with radio/antenna models

Ad Hoc Routing

Four routing protocols currently supported: DSDV

Contributed by CMU DSR

Contributed by CMU; recently updated AODV

Recently updated from Univ. of Cincinnati TORA

Contributed by CMU Examples under tcl/test/test-suite-wireless- { lan-newnode.tcl, lan-aodv.tcl, lan-tora.tcl }

Creating Network

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

Links and queuing$ns <link_type> $n0 $n1 <bandwidth>

<delay> <queue_type> <link_type>: duplex-link, simplex-link <queue_type>: DropTail, RED, CBQ, FQ,

SFQ, DRR, diffserv RED queues

Creating Connection and Traffic

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

CBRset src [new

Application/Traffic/CBR] Exponential or Pareto

on-offset src [new

Application/Traffic/Exponential]set src [new

Application/Traffic/Pareto]

Creating Connection and Traffic II

TCPset tcp [new Agent/TCP]set tcpsink [new Agent/TCPSink]$ns attach-agent $n0 $tcp$ns attach-agent $n1 $tcpsink$ns connect $tcp $tcpsink

FTPset ftp [new Application/FTP]$ftp attach-agent $tcp Telnetset telnet [new Application/Telnet]$telnet attach-agent $tcp

Creating Event Scheduler

Create event schedulerset ns [new Simulator]

Schedule events$ns at <time> <event>

<event>: any legitimate ns/tcl commands$ns at 5.0 “finish”

Start scheduler$ns run

Tracing and Monitoring

Packet tracing: On all links: $ns trace-all [open out.tr w] On one specific link: $ns trace-queue $n0 $n1 $tr

<Event> <time> <from> <to> <pkt> <size> -- <fid> <src> <dst> <seq> <attr>

+ 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

Visualize trace in nam$ns namtrace-all [open test.nam w]

$ns namtrace-queue $n0 $n1

Archivos de salida de NS2

Mostrar los formatos de los archivos de salida de NS2.

Mostrar las herramientas de análisis de Unix cat, awk.

Preguntas