Ngô Hải Anh: IEEE 802.11 Simulation Using NS-2

[Source: https://www.evanjones.ca/ns2/]

What can I do with ns2?

Wired network simulations
Wireless network simulations
Includes common protocols (TCP, RealAudio, etc)
Many low level details are configurable (queuing policy, MAC protocol, etc)

High Level Structure

Library of C objects with TCL interfaces

Nodes
Routing Protocols
Application Protocols
etc.

Connect the objects together via TCL

Workflow

(Optional) Create custom ns2 object
Create TCL scenario file
Run the scenario to produce a trace file
Process the trace file to get results

Basic Wireless Scenario

Chain of 5 nodes, spaced 200m apart
Use DSDV routing
FTP transfer from one end to the other
Want to measure the throughput

Diagram

Options

# ===============
# Define options 
# ===============
set val(chan)         Channel/WirelessChannel  ;# channel type 
set val(prop)         Propagation/TwoRayGround ;# radio-propagation model 
set val(ant)          Antenna/OmniAntenna      ;# Antenna type 
set val(ll)           LL                       ;# Link layer type 
set val(ifq)          Queue/DropTail/PriQueue  ;# Interface queue type 
set val(ifqlen)       50                       ;# max packet in ifq 
set val(netif)        Phy/WirelessPhy          ;# network interface type 
set val(mac)          Mac/802_11               ;# MAC type 
set val(rp)           DSDV                     ;# ad-hoc routing protocol  
set val(nn)           5                        ;# number of mobilenodes

Set Up Simulator

# Create simulator
set ns_    [new Simulator]

# Set up trace file
$ns_ use-newtrace
set tracefd [open simple.tr w]
$ns_ trace-all $tracefd

# Create the "general operations director"
# Used internally by MAC layer: must create!
create-god $val(nn)

# Create and configure topography (used for mobile scenarios)
set topo [new Topography]
# 1000x1000m terrain
$topo load_flatgrid 1000 1000

Configure Nodes

$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) \
        -channel [new $val(chan)] \
        -topoInstance $topo \
        -agentTrace ON \
        -routerTrace ON \
        -macTrace OFF \
        -movementTrace OFF

Create Nodes

for {set i 0} {$i < $val(nn) } {incr i} {
        set node_($i) [$ns_ node]       
        $node_($i) random-motion 0  ;# disable random motion
        $node_($i) set X_ 0.0
        $node_($i) set Y_ 0.0
        $node_($i) set Z_ 0.0
}

$node_(0) set X_ 0.0
$node_(1) set X_ 200.0
$node_(2) set X_ 400.0
$node_(3) set X_ 600.0
$node_(4) set X_ 800.0

Source and Destination

# 1500 - 20 byte IP header - 40 byte TCP header = 1440 bytes
Agent/TCP set packetSize_ 1440 ;# This size EXCLUDES the TCP header

set agent [new Agent/TCP]
set app [new Application/FTP]
set sink [new Agent/TCPSink]

$app attach-agent $agent

$ns_ attach-agent $node_(0) $agent
$ns_ attach-agent $node_(4) $sink
$ns_ connect $agent $sink

Node Structure

Run It

# 120 seconds of running the simulation time
$ns_ at 0.0 "$app start"
$ns_ at 120.0 "$ns_ halt"
$ns_ run

$ns_ flush-trace
close $tracefd

Trace File

s -t 0.000000000 -Hs 0 -Hd -2 -Ni 0 -Nx 0.00 -Ny 0.00 -Nz 0.00 -Ne -1.000000 -Nl AGT ...
r -t 0.000000000 -Hs 0 -Hd -2 -Ni 0 -Nx 0.00 -Ny 0.00 -Nz 0.00 -Ne -1.000000 -Nl RTR ...

Each line represents a message being transferred
Common fields:

Event type (s = send, r = received, d = drop)

Time stamp
Source and destination
XYZ co-ordinates of the node
Network layer (AGT = agent, RTR = router, ...)
... many many others

Miscellaneous Tools

Both command line tools and a Python API [details]
ns2stats.py: Aggregate statistics
throughputOverTime.py: Throughput per second
stupidplot.py: Plot data from Python

Throughput Over Time Output

Time    0:0 -> 4:0      4:0 -> 0:0
1.0     0.0     0.0
2.0     0.0     0.0
3.0     0.0     0.0
4.0     0.0     0.0
5.0     0.0     0.0
6.0     0.0     0.0
7.0     0.0     0.0
8.0     0.0     0.0
9.0     0.0     0.0
10.0    0.0     0.0

Stick it in GnuPlot

if len( sys.argv ) != 3:
        print "example.py trace-file output-eps-file"
        sys.exit( 1 )

input = file( sys.argv[1] )
flows = flowanalysis.parseFlowsFromTrace( input )
input.close()

data = throughputOverTime.throughputOverTime( flows )

stupidplot.gnuplotTable( data, sys.argv[2] )

Results

Random Tips and Tricks

Automate everything
Use command line parameters to customize scenario
Read the trace files to understand what is happening
GnuPlot sucks, but its the best thing available

Resources
http://evanjones.ca/ns2.html

# File: simple.tcl
# ====================================================================== 
# Define options 
# ====================================================================== 
set val(chan)         Channel/WirelessChannel   ;# channel type 
set val(prop)         Propagation/TwoRayGround  ;# radio-propagation model 
set val(ant)          Antenna/OmniAntenna       ;# Antenna type 
set val(ll)           LL                        ;# Link layer type 
set val(ifq)          CMUPriQueue               ;# Interface queue type 
set val(ifqlen)       50                        ;# max packet in ifq 
set val(netif)        Phy/WirelessPhy           ;# network interface type 
set val(mac)          Mac/802_11                ;# MAC type 
set val(rp)           DSR                       ;# ad-hoc routing protocol  
set val(nn)           5                         ;# number of mobilenodes 


# Create simulator
set ns_    [new Simulator]

# Set up trace file
$ns_ use-newtrace
set tracefd [open simple.tr w]
$ns_ trace-all $tracefd

# Create the "general operations director"
# Used internally by MAC layer: must create!
create-god $val(nn)


# Create and configure topography (used for mobile scenarios)
set topo [new Topography]
# 1000x1000m terrain
$topo load_flatgrid 1000 1000

$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) \
 -channel [new $val(chan)] \
 -topoInstance $topo \
 -agentTrace ON \
 -routerTrace ON \
 -macTrace OFF \
 -movementTrace OFF

for {set i 0} {$i < $val(nn) } {incr i} {
 set node_($i) [$ns_ node] 
 $node_($i) random-motion 0  ;# disable random motion
 $node_($i) set Y_ 0.0
 $node_($i) set Z_ 0.0
}

$node_(0) set X_ 0.0
$node_(1) set X_ 200.0
$node_(2) set X_ 400.0
$node_(3) set X_ 600.0
$node_(4) set X_ 800.0


# 1500 - 20 byte IP header - 40 byte TCP header = 1440 bytes
Agent/TCP set packetSize_ 1440 ;# This size EXCLUDES the TCP header

set agent [new Agent/TCP]
set app [new Application/FTP]
set sink [new Agent/TCPSink]

$app attach-agent $agent

$ns_ attach-agent $node_(0) $agent
$ns_ attach-agent $node_(4) $sink
$ns_ connect $agent $sink

# 120 seconds of running the simulation time
$ns_ at 0.0 "$app start"
$ns_ at 120.0 "$ns_ halt"
$ns_ run

$ns_ flush-trace
close $tracefd

Installation Notes

Error:

checking for tclsh8.4... /usr/bin/tclsh8.4
configure: error: Installation of tcl seems incomplete or can't be found automatically.
Please correct the problem by telling configure where tcl is
using the argument --with-tcl=/path/to/package
(perhaps after installing it),
or the package is not required, disable it with --with-tcl=no.

Solved: install 'tcl' package

make clean

make depend

g++  -Wall -Wno-write-strings -DCPP_NAMESPACE=std -o ucb-tr-stat tr-stat.o logparse.o utils.o -L/home/acgrid/ns2/lib -ltcl8.5  -lnsl -lpcap -ldl -lm
make[1]: Leaving directory `/home/acgrid/ns2/ns-2.35.test/indep-utils/webtrace-conv/ucb'

Ngô Hải Anh

Saturday, May 01, 2010

IEEE 802.11 Simulation Using NS-2

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