ns2 (network simulator version 2)

無線暨行動通訊實驗室 1

NS2 (Network Simulator version 2)

國立中正大學資訊工程研究所無線暨行動通訊研究室

報告人：江昭佑指導教授：陳裕賢副教授日期： 92 年 11 月 19 日


Outline

Introduction and the elements of ns2 Overview Tcl Script Overview nam Animation How to analyze the performance of protocols How to run wireless simulations in ns

Generating node-movement and traffic-connection files for large wireless scenarios

Homework


Introduction and the elements of ns2


Introduction

1. 在 1.0 秒時 , 假設 A 點送出了一個封包； 2. 在 1.005 秒時 , A 點上的網路卡開始解析封包 , 並進行傳送； 3. 在 1.006 秒時 , B 點收到了 A 點送過來的封包； 4. 在 1.1 秒時 , B 點的網路卡解析封包 , 並送給 B 點的應用程

式

NS is a discrete event simulator targeted at networking research


The elements of NS2

OTcl (version 1.0a8) Tcl (version 8.3.2) Tk (version 8.3.2) Nam (version 1.9) Tclcl (version 1.0b13) Xgraph (version 12.1)


Simplified User’s View of NS


C++ and OTcl


Architectural View of NS


The Procedure of using NS2


Overview Tcl Script


What is Tcl/Tk Tcl/Tk 是什麼

Tcl/Tk 是一個跨平臺 (cross-platform)﹑ 可擴充 (extensible) 的高階 scripting 語言 , 可用以發展 GUI 應用程式

還有那些具有相近優點的語言可以考慮 Java, Perl/Tk, Python/Tk, Guile/Tk

Tcl/Tk 的優缺點基本功能簡單易上手；程式囉嗦沒有複雜的資料結構 incr Tcl 可提供物件導向功能，但受限於語言基本架構，很難

把所有重要物件導向功能完整表達 . Tk 提供的功能幾乎已成為所有此類 ( 跨平臺 , 可擴充 ) 語

言的標準 GUI 元件。也可以 ( 不太精確地 ) 說： Tk 語言不僅跨平臺， Tk 的觀念與術語甚至跨程式語言，對於程式設計師而言，是具有前瞻性，值得長期投資心力學習的工具 (Tool Kit)


Introduction of OTcl syntax(set variable number)

# 設定 x 變數， x 值為 100( 注意這 100 是字串 ) set x 100

# 設定 y 變數， y 值為 200 set y 200

# 透過 expr 將 $x $y 當成數字作數學運算 , 並設定 z 變數為 300 set z [expr $x+$y]

# 設定 a = b = 100 set a [set b 100]

# 設定一個陣列叫 array_, 並把 array_(1) 的值設為 27 set array_(1) 21


Introduction of OTcl syntax(if-else)

if 的範例範例說明 : 如果變數 k 大於 4, 則顯示出 “ k > 4”, 反之則顯示 “ k < =4 ” ，要注意的是 if 後面接的是大括號 “ {” ，不同於我們在 C 語言中所寫的 “ (” 。

if { $k>4 } { puts " k > 4 " } else { puts " k < = 4 " }

while 的範例範例說明：下面程式，代表一個 while 如在 i 大於等於 0 的情況下，則將 b 的值和 i 相加並再回傳給 b ，然後 i 再減 1

set b 0 set i 100 while {$i > = 0} { set b [expr $b+$i] incr i -1 } for 的範例 for {set i 100} {$i > =0} {incr i -1} { # for 迴圈內所要執行的程式碼 }


Introduction of OTcl syntax(sub-function)

# 定義一個叫做 show 的 procedure proc show {} { ... # 副程式內容 ... }

# 範例 : ( 計算 x 階乘的 procedure) proc fac {x} { if {$x < 0} { error "Invalid argument $x: must be a positive integer" } elseif {$x < = 1} { return 1 } else { return [expr $x * [fac [expr $x-1]]] } }


A Sample Tcl Script


A Sample OTcl Script


Overview nam Animation


Nam tool

Nam is a Tcl/TK based animation tool for viewing network simulation traces and real world packet traces. It supports topology layout, packet level animation, and various data inspection tools.


Nam environment


Nam example (Rate-based Pacing Animation )


Xgraph tool


How to analyze the performance of protocols


Trace file 假如我們的 tcp script 有做 trace-all 的動作 , 那當

我們執行完 ns2 之後 , 就會產生一個紀錄的檔案 , 而這個檔案主要就是紀錄一些 packet 在我們模擬中的傳輸情況 . 我們可以試著去打開這個檔案來研究看看 , 如下 :


Definition of flags 1 代表事件的類別

r ：代表目的端收到 packet + ：代表 packet 放入 queue 中 - ：代表 packet 從 queue 中取出 d ：代表 queue 已經滿了，這個 packet 被 drop 掉

2 代表事件發生的時間 3 代表 packet 的 source node 4 代表 packet 的 destination node 5 代表 packet 的類別 6 代表 packet 的大小 (encoded in IP header) 7 代表 packet 的 flags 8 代表 connection(flow) 的 id 9 代表 source address ( node.port ) 10 代表 destinations address ( node.port ) 11 代表 packet 的 sequence number ( network layer protocol's ) 12 代表 packet 的 id ( unique )


How to run wireless simulations in ns


Tcl program in wireless scenario

set val(chan) Channel/WirelessChannel set val(prop) Propagation/TwoRayGround set val(netif) Phy/WirelessPhy set val(mac) Mac/802_11 set val(ifq) Queue/DropTail/PriQueue set val(ll) LL set val(ant) Antenna/OmniAntenna set val(x) 670 ;# X dimension of the topography set val(y) 670 ;# Y dimension of the topography set val(ifqlen) 50 ;# max packet in ifq set val(seed) 0.0 set val(adhocRouting) DSR set val(nn) 3 ;# how many nodes are simulated set val(cp) "../mobility/scene/cbr-3-test" set val(sc) "../mobility/scene/scen-3-test" set val(stop) 2000.0 ;# simulation time



set tracefd [open wireless1-out.tr w] ;# for wireless traces

$ns_ trace-all $tracefd

set namtrace [open wireless1-out.nam w] ;# for nam tracing

$ns_ namtrace-all-wireless $namtrace $val(x) $val(y)



# # Define node movement model # puts "Loading connection pattern...“source $val(cp) # # Define traffic model # puts "Loading scenario file..." source $val(sc)



$ns_ at 50 "$node_(2) setdest 369.4 170.5 3.37“

$god_ set-dist 1 2 2



# Define node initial position in nam for {set i 0} {$i < $val(nn)} {incr i} { # 20 defines the node size in nam, must adjust it

according to your # scenario size. # The function must be called after mobility

model is defined $ns_ initial_node_pos $node_($i) 20 }



puts $tracefd "M 0.0 nn $val(nn) x $val(x) y $val(y) rp $val(adhocRouting)"

puts $tracefd "M 0.0 sc $val(sc) cp $val(cp) seed $val(seed)"

puts $tracefd "M 0.0 prop $val(prop) ant $val(ant)"



ns wireless1.tcl


Creating random traffic-pattern for wireless scenarios

ns cbrgen.tcl [-type cbr|tcp] [-nn nodes] [-seed seed] [-mc connections] [-rate rate]

ns cbrgen.tcl -type cbr -nn 10 -seed 1.0 -mc 8 -rate 4.0 > cbr-10-test


Creating random traffic-pattern for wireless scenarios

./setdest [-n num_of_nodes] [-p pausetime] [-s maxspeed] [-t simtime] [-x maxx] [-y maxy] > [outdir/movement-file]

./setdest -n 20 -p 2.0 -s 10.0 -t 200 -x 500 -y 500 >

scen-20-test


Reference

http://www.isi.edu/nsnam/ns/tutorial/index.html (tutorial for the network simulator)

http://nile.wpi.edu/NS/ (ns by example) http://netlab.cse.yzu.edu.tw/ns2/ns2_websit

e/ (learning ns website)


Homework

Performance Evaluation of Ad Hoc Routing Protocols using ns2 simulations Dynamic Source Routing (DSR) Ad-Hoc On-Demand Distance Vector Routing

(AODV) Temporally Order Routing Algorithm (TORA) Destination-Sequenced Distance-Vector

(DSDV)


Simulation model

Traffic models ~/ns/indep-utils/cmu-scen-gen

Mobility models ~ns/indep-utils/cmu-scen-gen/setdest


Performance Matrics

Packet delivery fraction The ratio of the data packets delivered to the

destinations to those generated by the CBR sources. Average end-to-end delay of data packets

This includes all possible delays caused by buffering during route discovery latency, queuing at the interface queue, retransmission delays at the MAC, and propagation and transfer times.


Performance Metrics

Normalized routing load The number of routing packets transmitted per data

packet delivered at the destination. Each hop-wise transmission of a routing packet is counted as one transmission.


Detail of Performance Metrics Evaluating Packet delivery fraction (pdf)

Calculate the number of “sent packets” that have the trace form Calculate the number of “received packets” of the trace form Packet delivery fraction (pdf %) = (received packets / sent

packets) *100 Evaluating Average End-End packet delivery time

For each packet with id of trace level (AGT) and type (CBR), calculate the send(s) time(s) and the receive(r) time(t) and average it

Evaluating Normalized routing load Normalized routing load = (routing packets sent) / receives


Examples(PDF v.s. Pause time)

Packet Delivery Fraction (PDF)

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100

Pause time (secs)

Packet

delivery

fra

cti

on

(%

)

AODV, 20 sources

DSR, 20 sources

DSDV, 20 sources


Examples (Average End-to-End delay v.s. Pause time)

Average End-End delay

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0 10 20 30 40 50 60 70 80 90 100

Pause time (secs)

Ave

rag

e d

elay

(se

cs) AODV, 20 sources

DSR, 20 sources

DSDV, 20 sources


Basic and Advanced function

Basic Area is 500X500m The number of nodes is 20

Advanced function Comparison of different number of nodes Comparison of different size of area


~ ~ The End ~ ~

Thank you for your attention to my presentation !

ns2 (network simulator version 2)

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