Università degli Studi di CataniaCorso di Laurea Magistrale in Ingegneria Informatica

Giancarlo RomeoO55 000031

Use of NS-2 to simulate MANET routing algorithms

Architectures and tecnologies for telecommunications systemsProf. Eng. Giacomo Morabito

Ad hoc networks

“A mobile ad hoc network, is a self-configuring infrastructureless network of mobile devices connected by wireless links”.

There is no static infrastructure such as base station. If two hosts are not within radio range, all message communication between them must pass

through one or more intermediate hosts that double as routers.

Source node

Destination node

Mobile Ad hoc NETwork

Route DiscoveryForward

Route Error

Broken Link

Ad hoc routing protocols

Minimize number of exchanged messages

Simplify processing and routing operations

Keeping updated the network scenario

Prevent loops inside the network

Targets

to Steve

Ad hoc routing protocols: pro-active vs. reactive

Maintains fresh lists of destinations and their routes by periodically distributing routing tables throughout the network. The main disadvantages of such algorithms are:

1. Respective amount of data for maintenance.2. Slow reaction on restructuring and failures.

Finds a route on demand by flooding the network with Route Request packets. The main disadvantages of such algorithms are:

1. High latency time in route finding.2. Excessive flooding can lead to network clogging.

Pro-active (table-driven)

Reactive (on-demand)

DSDV (Destination-Sequenced Distance Vector)

DSDV is a table-driven routing scheme for ad hoc mobile networks based on the Bellman-Ford algorithm.

Guarantees for loop free paths (sequence numbers).

Requires a regular update of its routing tables, which uses up battery power and a small amount of bandwidth even when the network is idle.(full dumps and smaller incremental updates).

Advantages

Disadvantages

Since each node knows the complete topology, a node can immediately find the best route to a destination.

AODV (Ad hoc On-Demand Distance Vector)

Guarantees for loop free paths (sequence numbers).

AODV is a reactive routing protocol, meaning that it establishes a route to a destination only on-demand.

Low bandwidth utilization for path keeping.

The connection setup delay is higher (route discovery).

Advantages

Disadvantages

Network Simulator 2 (ns-2)

NS-2 is a discrete event simulator targeted at networking research. Ns provides substantial support for simulation of TCP, routing, and multicast

protocols over wired and wireless (local and satellite) networks.

Transmission ranges

Mobile node

Timeline

Scenarios

Nodes

Area

Speed

Simulation time

$ util/scenariogen -v 2 -n $opt(nn) -s 1 -m $opt(minspeed) -M $opt(maxspeed) -t 300 -P 1 -p 2.0 \-x $opt(x) -y $opt(y) > scenarios/scenario.tcl

Parameters

Free space where mobile nodes move on.

Number of mobile nodes in the area.

Min and max speed of nodes [in m/s].

Duration of simulation [in s].

util/scenariogen

x

yv

v

v

v

v

v

v

v

v

Mobile node

A program that creates TCL script for modeling mobile scenario.

Propagation model

Two-ray ground reflection model

ht hr

d

direct ray

reflect ray

threshold.cc

$ ./util/threshold -m TwoRayGround 120

A C++ program that calculates the thresholds for transmission receipt using the relation between various physical parameters (distance, effect, propagation model etc.) related to transmissions in ns-2.

Propagation model

Distance in meters

Power received at distance d

ground

Tx

Rx

CS Threshold and RX Threshold

RxThresh_CSThresh_

PHY module discards frame

Physical transmission modeling

CSThresh_

RXThresh_

NS2 mainly uses thresholds to determine whether one frame is received correctly by the receiver.

If signal strenght of the frame is less than CSThresh_, the frame is discarded in PHY module and not will be visible to MAC layer.

If signal strenght of the frame is stronger than RXThresh_, the frame is discarded in received correctly. Otherwise, the frame is tagged as corrupted and MAC layer will discard it.

MAC tags corrupted frame

Good frame

Traffic

Nodes

Protocol

Connections

$ util/trafficgen.tcl -nn $opt(nn) -cn $opt(cn) > traffic/traffic.tcl

Type of communication protocol. (e.g. TCP)

Number of mobile nodes.

Number of connections between mobile nodes.

Parameters

util/trafficgen.tcl

FTPFTPApplication

Agent

Tx Rx

create-connection

TCP SinkTCP

Communication model stack

An OTCL script that creates traffic between nodes in ns-2.

MAC / PHY Layer

util/trafficgen.tcl

proc tcp_connect {src dst} { global ftp_cnt opt; puts "\n# Node $src connecting through TCP to Node $dst." # create TCP Agent and attach it to the source node puts "set tcp_($ftp_cnt) \[new Agent/TCP\]" puts "\$ns_ attach-agent \$node_($src) \$tcp_($ftp_cnt)" puts "\$tcp_($ftp_cnt) set window_ $opt(winsize)" puts "\$tcp_($ftp_cnt) set packetSize_ $opt(pktsize)" # create TCPSink Agent and attach it to the destination node puts "set sink_($ftp_cnt) \[new Agent/TCPSink\]" puts "\$ns_ attach-agent \$node_($dst) \$sink_($ftp_cnt)" # create a connection between source and destination puts "\$ns_ connect \$tcp_($ftp_cnt) \$sink_($ftp_cnt)" # create an FTP Application and attach it to the source node puts "set ftp_($ftp_cnt) \[new Application/FTP\]" puts "\$ftp_($ftp_cnt) attach-agent \$tcp_($ftp_cnt)" puts "set ftp_($ftp_cnt) \[\$tcp_($ftp_cnt) attach-source FTP\]" # starts the FTPs transmission puts "\$ns_ at 0 \"\$ftp_($ftp_cnt) start\"" incr ftp_cnt}

Procedures/tcp-connectwhile {$ftp_cnt < $opt(cn)} { set src [expr int(rand() * $opt(nn))] while 1 { set dst [expr int(rand() * $opt(nn))] if {$src != $dst} { break } } tcp_connect $src $dst}

Main

FTPFTPApplication

Agent

Tx Rx

create-connection

TCP SinkTCP

Connects source and destination

sim.tcl

Options

set opt(chan)set opt(prop)set opt(ant)set opt(ll)set opt(ifq)set opt(ifqlen)set opt(netif)set opt(mac)set opt(rp) set opt(nn)set opt(pktsize)

Channel/WirelessChannel ;# channel typePropagation/TwoRayGround ;# radio-propagation modelAntenna/OmniAntenna ;# antenna typeLL ;# link layer typeQueue/DropTail/PriQueue ;# interface queue type50 ;# max packet in ifqPhy/WirelessPhy ;# network interface typeMac/802_11 ;# MAC typeDSDV ;# ad-hoc routing protocol 300 ;# number of mobilenodes

Procedures

proc finish {} {...}proc getargs {argc argv} {...}proc usage {} {...}

Physical configuration

sim.tclMain

getargs $argc $argvset ns_ [new Simulator]

set tracef [open traces/$opt(sim)/[string tolower $opt(rp)]/trace_$opt(par).tr w]$ns_ trace-all $tracef

set topo [new Topography]$topo load_flatgrid $opt(x) $opt(y)

set god_ [create-god $opt(nn)]

$ns_ node-config -adhocRouting $opt(rp) \ -llType $opt(ll) \ -macType $opt(mac) \ -ifqType $opt(ifq) \ -ifqLen $opt(ifqlen) \ -antType $opt(ant) \ -propType $opt(prop) \ -phyType $opt(netif) \ -topoInstance $topo \ -channel [new $opt(chan)]

Node configuration

Open trace file

sim.tclMain

for {set i 0} {$i < $opt(nn)} {incr i} { set node_($i) [$ns_ node] $node_($i) random-motion 0 $ns_ initial_node_pos $node_($i) 10}

source scenarios/$opt(sim)/scenario_$opt(par).tclsource traffic/sim$sim/traffic.tcl

$ns_ at $opt(duration) "finish"$ns_ run

Import scenario and traffic files

Initialize nodes

Optionsset opt(nn)set opt(x)set opt(y)set opt(cn)

set opt(nsim)set opt(rp)

set opt(minspeed)set opt(maxspeed)

10050050030

5{AODV DSDV}

{0.1 5.1 10.1 15.1 20.1}{5.0 10.0 15.0 20.0 25.0}

;# number of nodes;# area width;# area length;# number of connections

;# number of simulations;# routing protocols

;# minimum speed;# maximum speed

allsim.tcl

4. analize-traces3. run-simulations

1. create-scenarios 2. create-traffic

allsim.tcl

sim.tclutil traces_analizer.awk

trafficgen.tclscenariogen

Architecture

Procedures: create-scenarios

proc create-scenarios {} {global opt

file mkdir scenariosfor {set sim 1} {$sim <= $opt(nsim)} {incr sim} {

puts "Creating simulation n.$sim"

file mkdir scenarios/sim$simfor {set j 0} {$j < 5} {incr j} {

puts " Creating scenario (m=[lindex $opt(minspeed) $j] m/s, M=[lindex $opt(maxspeed) $j] m/s)"puts " => Writing \"scenarios/sim$sim/scenario_[expr $j+1].tcl\""

exec util/scenariogen -v 2 -n $opt(nn) -s 1 -m [lindex $opt(minspeed) $j] -M [lindex $opt(maxspeed) $j] \-t 300 -P 1 -p 2.0 -x $opt(x) -y $opt(y) > scenarios/$sim/scenario_[expr $j+1].tcl

} } puts "Scenarios have been successfully created!\n" puts "Press any key to continue..." gets stdin -}

allsim.tcl

Creates scenarios

Number of simulations

Procedures: create-traffic

proc create-traffic {} { global opt file mkdir traffic for {set sim 1} {$sim <= $opt(nsim)} {incr sim} {

puts "Creating simulation n.$sim"

file mkdir traffic/sim$sim puts " Creating traffic (nn=$opt(nn), cn=$opt(cn))"

puts " => writing \"traffic/sim$sim/traffic.tcl\"\n" exec ns util/trafficgen.tcl -nn $opt(nn) -cn $opt(cn) > traffic/sim$sim/traffic.tcl

}

puts "Traffic has been successfully created!" puts "\nPress any key to continue..." gets stdin -}

Creates traffic

allsim.tcl

Number of simulations

allsim.tclProcedures: run-simulations

proc run-simulations {} {global opt

for {set sim 1} {$sim <= $opt(nsim)} {incr sim} {puts "Running simulation n.$sim"

foreach rp $opt(rp) {puts " Simulating $rp algorithm"

for {set j 0} {$j < 5} {incr j} {puts " Running simulation (speed=[lindex $opt(minspeed) $j]-[lindex $opt(maxspeed) $j])"puts " => writing \"traces/sim$sim/$rp/trace_[expr $j+1].tr\""catch {exec ns sim.tcl -nn $opt(nn) -rp $rp -x $opt(x) -y $opt(y) -sim $sim -par [expr $j+1]}

} } } puts "Simulations have been successfully executed!" puts "\nPress any key to continue..." gets stdin -}

Runs simulation on NS2

Number of simulations

Procedures: analize-traces

proc analize-traces {} {global optputs "Analyzing traces"

file mkdir resultsforeach rp $opt(rp) {

puts " Analyzing $rp algorithm"file mkdir results/[string tolower $rp]for {set j 0} {$j < 5} {incr j} {

set resultsf [open results/[string tolower $rp]/results_[expr $j+1].txt w]puts " => writing \"results/[string tolower $rp]/results_[expr $j+1].txt\""

for {set sim 1} {$sim <= $opt(nsim)} {incr sim} {puts $resultsf [exec awk -f util/traces_analizer.awk traces/$sim/[string tolower $rp]/trace_[expr $j+1].tr]

} close $resultsf } } puts "Calculating throughput has been successfully executed!" puts "\nPress any key to continue..." gets stdin -}

allsim.tcl

Filters trace files with awk and computes throughput

Main

while 1 {exec clear >@ stdout

puts "Welcome to NS2 Ad-hoc Network Simulator"puts "-- Speed ------------------------------\n"puts "Simulation info:"puts " Nodes: \t\t $opt(nn)"puts " Grid: \t\t $opt(x) m x $opt(y) m"puts " Connections: \t\t $opt(cn)"puts " Algorithms: \t\t $opt(rp)"

puts "\nCommand menu:"puts " 1. Create scenarios (varying max speed 5-25 m/s)"puts " 2. Create traffic"puts " 3. Run simulation on NS2"puts " 4. Analize traces"puts "\n 0. Exit"puts "\nWhat dou you choose?"gets stdin i

switch $i {1 {create-scenarios}2 {create-traffic}3 {run-simulations}4 {analize-traces}0 {exit 0}

}}

allsim.tcl

Running allsim.tcl script screenshot

$ tclsh allsim.tcl

Usage

Interactive menu

Simulations/Speed

Connections: 30

Nodes: 100

Area: 500m x 500m

Speed: {5.0 10.0 15.0 20.0 25.0} m/s

CSThreshold: 120m

RXThreshold: 80m

0Kb

160Kb

320Kb

480Kb

640Kb

800Kb

5 m/s 10 m/s 15 m/s 20 m/s 25 m/s

727K

208K

91K 81K 56K

792K

531K

406K353K 321K

Thr

ough

put

Nodes speed

AODV DSDV

+overhead

high link failures

Simulations/Nodes

Connections: 30

Area: 500m x 500m

Nodes: {50 75 100 125 150}

CSThreshold: 120m

RXThreshold: 80m

10 m/s

0Kb

120Kb

240Kb

360Kb

480Kb

600Kb

50 75 100 125 150

226K 240K

134K

193K146K

591K 580K

428K482K

458K

Thr

ough

put

Number of nodes

AODV DSDV

+overhead

high link failures

Simulations/Nodes

Connections: 30

Area: 500m x 500m

Nodes: {50 75 100 125 150}

CSThreshold: 120m

RXThreshold: 80m

20 m/s

0Kb

80Kb

160Kb

240Kb

320Kb

400Kb

50 75 100 125 150

51K35K

68K47K 59K

364K 363K 362K332K 329K

Thr

ough

put

Number of nodes

AODV DSDV

+overhead

high link failures

Simulations/Nodes

Connections: 30

Area: 500m x 500m

Nodes: {50 75 100 125 150}

CSThreshold: 120m

RXThreshold: 80m

10-20 m/s

0Kb

120Kb

240Kb

360Kb

480Kb

600Kb

50 75 100 125 150

226K 240K

134K

193K146K

591K 580K

428K482K

458K

51K 35K68K 47K 59K

364K 363K 362K332K 329K

Thr

ough

put

Number of nodes

AODV 10 m/sDSDV 10 m/sAODV 20 m/sDSDV 20 m/s

+overhead

high link failures

Simulations/Range

Connections: 30

Nodes: 100

Area: 500m x 500m

CSThreshold: 120m

RXThreshold: 80m

0K

120K

240K

360K

480K

600K

130 125 124 123 122 121 120 115 110 100 80 60 40

Thr

ough

put

Range

AODV DSDV

Range: {130 ... 120 100 80 60 40}

+overhead

high link failures

tx range too small

DSDV vs. AODV

Better throughput: low bandwidth utilization for link

keeping.

High latency: the connection setup delay is higher (route discovery).

Worst throughput: high bandwidth utilization for link

keeping.

Low latency: the connection setup delay is lower (update table).

DSDV AODV