Simulation of Routing Protocols in Mobile Ad-Hoc Networks - Nusrah Kanwal

Simulation of Routing Protocols in Mobile

Ad-Hoc Networks

Submitted By

Nusrah Kanwal BETL – F05 - 0136

[email protected]

Project Supervisor

Shams Ul Arfeen

FACULTY OF ENGINEERING SCIENCES & TECHNOLOGY

Hamdard Institute of Information Technology

Hamdard University, Main Campus, Karachi, Pakistan.

NOVEMBER 2009

ii

Dedication

This report is dedicated to Shaheed Hakim Mohammad Saeed, my Teachers, my Supervisor, my

Parents, my fellow colleagues and the hard working students of HIIT with a hope that they will

succeed in every aspect of their Academic Career.

iii

Acknowledgement

In the name of Allah, the Most Gracious and the Most Merciful.

Peace and blessings of Allah be upon Prophet Muhammad (SAWW).

First and foremost, praise be to Allah, for giving me this opportunity, the strength and the

patience to complete my dissertation finally, after all the challenges and difficulties. I would like

to thank my supervisor, Shams Ul Arfeen for his highly motivated and most significant

contribution in this project. I would also like to thank my parents for financial and moral support

and also my friends who have helped and motivated me throughout.

May Allah reward them all abundantly.

Nusrah Kanwal

BETL – F05 – 0136

iv

Certificate

This is to certify that Ms. Nusrah Kanwal, D/O Syed Muhammad Farooq, BETL/F05/0136

have successfully completed her final year project. This project, “Simulation of Routing

Protocols in Mobile Ad-Hoc Networks” was assigned to her, to fulfill the partial requirement

for the bachelor degree of Telecommunication Engineering.

(Shams Ul Arfeen)

Project Supervisor

(Rashid Hussain)

Member

Project Committee

(Ahmed Sikandar)

Member

Project Committee

(Fahad Azim)

Deputy Director, HIIT

(Dr. Iqbal Ahmed Khan)

Director, HIIT

v

Table of Contents

Dedication ................................................................................................................................. ii

Acknowledgement ................................................................................................................... iii

Certificate ................................................................................................................................ iv

Table of Contents ..................................................................................................................... v

List of Tables ......................................................................................................................... viii

List of Figures .......................................................................................................................... ix

List of Graphs ........................................................................................................................... x

Abbreviations .......................................................................................................................... xi

Abstract ................................................................................................................................. xiii

1. Introduction to MANET ................................................................................................... 1

1.1. Background................................................................................................................. 1

1.2. Classification of Ad hoc Networks .............................................................................. 1

1.2.1. Infrastructure based wireless networks.............................................................................. 1

1.2.2. Ad hoc wireless networks(infrastructure less) ................................................................... 2

1.3. Overview of MANETs ................................................................................................ 2

1.4. Issues in MANET ....................................................................................................... 3

1.5. Aims and Objectives ................................................................................................... 4

1.6. Thesis structure ........................................................................................................... 4

2. Mobile Ad hoc Routing Protocols ..................................................................................... 5

2.1. MANET Routing Overview ........................................................................................ 5

2.2. Classification of Routing Protocols ............................................................................. 6

2.2.1. Proactive Routing Protocols ............................................................................................. 6

2.2.2. Reactive Routing Protocols .............................................................................................. 7

2.2.3. Hybrid Routing Protocols ................................................................................................. 7

2.3. Analysis of MANET Routing Protocols ...................................................................... 7

2.3.1. Ad hoc On-demand Distance Vector Routing (AODV) ..................................................... 8

2.3.1.1. Description .................................................................................................... 8

2.3.1.1.1. Route table management............................................................................. 9

2.3.1.1.2. Route discovery ........................................................................................ 9 2.3.1.1.3. Route Maintenance ................................................................................. 10

vi

2.3.1.2. Properties .................................................................................................... 10

2.3.2. Destination Sequenced Distance Vector Routing (DSDV) .............................................. 10

2.3.2.1. Description .................................................................................................. 10

2.3.2.2. Properties .................................................................................................... 12

2.3.3. Dynamic Source Routing (DSR) ..................................................................................... 12

2.3.3.1. Description .................................................................................................. 12

2.3.3.1.1. Route Discovery ..................................................................................... 13

2.3.3.1.2. Route Maintenance ................................................................................. 14 2.3.3.2. Properties .................................................................................................... 14

2.3.4. Temporarily Ordered Routing Algorithm (TORA) .......................................................... 15

2.3.4.1. Description .................................................................................................. 15

2.3.4.2. Properties .................................................................................................... 17

2.4. Comparison............................................................................................................... 17

3. Simulation Environment ................................................................................................. 19

3.1. Network Simulators Overview .................................................................................. 19

3.1.1. Network Simulator-2 ...................................................................................................... 20

3.1.2. GloMoSim ..................................................................................................................... 20

3.1.3. QualNet ......................................................................................................................... 21

3.1.4. OPNET .......................................................................................................................... 21

3.2. Choice of Simulator .................................................................................................. 22

3.2.1. NS-2 Working Flow ....................................................................................................... 23

3.2.1.1. Network Animator ........................................................................................ 23

3.2.1.2. Tool Command Language ............................................................................ 24

3.2.1.3. Trace File Format ........................................................................................ 27

3.2.1.4. AWK Script .................................................................................................. 28

4. Performance Analysis ..................................................................................................... 31

4.1. Simulation Parameters .............................................................................................. 31

4.2. Performance Analysis Factors ................................................................................... 32

4.3. Simulation Results .................................................................................................... 32

4.3.1. End to End Delay ........................................................................................................... 33

4.3.2. Normalized Routing Load .............................................................................................. 35

4.3.3. Packet Loss Ratio ........................................................................................................... 37

4.3.4. Routing Overhead .......................................................................................................... 39

4.3.5. Packet Delivery Fraction (PDF) ...................................................................................... 41

vii

5. Conclusion ....................................................................................................................... 43

5.1. Summary .................................................................................................................. 43

5.2. Future Work.............................................................................................................. 44

6. References ........................................................................................................................ 45

7. Appendix A ...................................................................................................................... 47

7.1. Installation Process of Linux ..................................................................................... 47

7.1.1. Introduction to VMware Workstation ............................................................................. 47

7.1.2. Creating new Virtual Machine ........................................................................................ 47

7.1.3. Installing VM Tools ....................................................................................................... 52

7.2. Installation Process of Network Simulator ................................................................. 53

7.2.1. Getting NS-2 .................................................................................................................. 53

7.2.2. Steps for Installation....................................................................................................... 53

8. Appendix B ...................................................................................................................... 55

8.1. AWK Program Used ................................................................................................. 55

viii

List of Tables

Table 1: DSDV Routing Table ................................................................................................. 11 Table 2: DSDV Routing Table ................................................................................................. 11

Table 3: Comparison of MANET Routing Protocols ................................................................. 17 Table 4: Simulation Parameters ................................................................................................ 31

Table 5: Simulation Results: End to End Delay ........................................................................ 33 Table 6: Simulation Results: Normalized Routing Load ........................................................... 35

Table 7: Simulation Results: Packet Loss Ratio ........................................................................ 37 Table 8: Simulation Results: Routing Overhead........................................................................ 39

Table 9: Simulation Results: Packet Delivery Fraction ............................................................. 41 Table 10: Comparison of MANET Routing Protocols (on the basis of results) .......................... 43

ix

List of Figures

Figure 1: MANET ...................................................................................................................... 2

Figure 2: Ad hoc On-demand Distance Vector Routing Protocol ................................................ 8 Figure 3: Destination Sequenced Distance Vector..................................................................... 11

Figure 4: Destination Sequenced Distance Vector..................................................................... 11 Figure 5: Dynamic Source Routing Protocol ............................................................................. 14

Figure 6: Temporarily Ordered Routing Algorithm ................................................................... 16 Figure 7: Simulators Utilization Trend...................................................................................... 19

Figure 8: NS-2 Working Flow .................................................................................................. 23 Figure 9: Screen Shot of Network Animator ............................................................................. 24

Figure 10: Old Wireless Trace File Format ............................................................................... 27 Figure 11: Screen Shot of VMware Workstation....................................................................... 47

Figure 12: Screen shot of New Virtual Machine Icon................................................................ 47 Figure 13: Screen Shot of New Virtual Machine Wizard 1........................................................ 48

Figure 14: Screen Shot of New Virtual Machine Wizard 2........................................................ 48 Figure 15: Screen Shot of CentOS Installation 1 ....................................................................... 49

Figure 16: Screen Shot of CentOS Installation 2 ....................................................................... 49 Figure 17: Screen Shot of CentOS Installation 3 ....................................................................... 50




Figure 24: Screen Shot of VM Tools Installation ...................................................................... 52 Figure 25: Screen Shot of VM Tools Icon................................................................................. 53

x

List of Graphs

Graph 1: End to End Delay [2 m/s] ........................................................................................... 34

Graph 2: End to End Delay [15 m/s] ......................................................................................... 34 Graph 3: End to End Delay [30 m/s] ......................................................................................... 34

Graph 4: End to End Delay [45 m/s] ......................................................................................... 34 Graph 5: Normalized Routing Load [2 m/s] .............................................................................. 36

Graph 6: Normalized Routing Load [15 m/s] ............................................................................ 36 Graph 7: Normalized Routing Load [30 m/s] ............................................................................ 36

Graph 8: Normalized Routing Load [45 m/s] ............................................................................ 36 Graph 9: Packet Loss Ratio [2 m/s] .......................................................................................... 38

Graph 10: Packet Loss Ratio [15 m/s] ....................................................................................... 38 Graph 11: Packet Loss Ratio [30 m/s] ....................................................................................... 38

Graph 12: Packet Loss Ratio [45 m/s] ....................................................................................... 38 Graph 13: Routing Overhead [2 m/s] ........................................................................................ 40

Graph 14: Routing Overhead [15 m/s] ...................................................................................... 40 Graph 15: Routing Overhead [30 m/s] ...................................................................................... 40

Graph 16: Routing Overhead [45 m/s] ...................................................................................... 40 Graph 17: Packet Delivery Fraction [2 m/s] .............................................................................. 42

Graph 18: Packet Delivery Fraction [15 m/s] ............................................................................ 42 Graph 19: Packet Delivery Fraction [30 m/s] ............................................................................ 42

Graph 20: Packet Delivery Fraction [45 m/s] ............................................................................ 42

xi

Abbreviations

AGT AGenT

AODV Ad hoc On-demand Distance Vector

AWK Aho Weinberger and Kernighan

BRP Bordercast Resolution Protocol

CBR Constant Bit Rate

CLR Clear

CMU Carngie Mellon University

DAG Directed Acyclic Graph

DSDV Destination Sequenced Distance Vector

DSR Dynamic Source Routing

DYMO Dynamic MANET On-demand

FAQ Frequently Asked Questions

GloMoSim Global Mobile information systems Simulation library

IARP IntrAzone Routing Protocol

IERP IntErzone Routing Protocol

IMEP Internet MANET Encapsulation Protocol

IP Internet IP

LAR Location Aided Routing

MAC Media Access Protocol

MANET Mobile Ad hoc NETworks

NAM Network Animator

NS Network Simulator

ODMRP On-Demand Multicast Routing Protocol

OLSR Optimized Link State Routing

OPNET Operations Network

OPSF Open Shortest Path First

OS Operation System

xii

PDF Packet Delivery Fraction

RREP Route REPly

RREQ Route REQuest

RTR RouTeR

SNT Scalable Network Technologies

STAR Source-Tree Adaptive Routing protocol

Tcl/Tk Tool Command Language

TCP Transmission Control Protocol

TORA Temporarily Ordered Routing Algorithm

UPD Update

QoS Quality of Service

QRY Query

VMware Virtual Machine ware

WRP Wireless Routing Protocol

ZRP Zone Routing Protocol

xiii

Abstract

A MANET is a collection of wireless mobile nodes dynamically forming a temporary

network without the use of any existing network infrastructure or centralized administration. Due

to the limited transmission range of a node, data is forwarded using multi-hops so that one node

can be able to exchange data with another node across the network.

A variety of new routing protocols targeted specifically at this environment have been

developed. This thesis presents the results of a detailed packet-level simulation comparing four

prominent MANET routing protocols: Ad hoc On-demand Distance Vector Routing (AODV),

Destination Sequenced Distance Vector Routing (DSDV), Dynamic Source Routing (DSR) and

Temporarily Ordered Routing Algorithm (TORA).

The comparison has been done on the basis of End to End Delay, Normalized Routing Load,

Packet Loss Ratio, Routing Overhead and Packet Delivery Fraction (PDF) by varying the

maximum speed and pause time.

The results reveal that DSDV shows a poor result as compared to AODV and DSR with

respect to packet delivery fraction. Also that DSDV will perform better in case of higher traffic

load, whereas, AODV and DSR will experience an increased overhead. DSDV is a proactive

routing protocol, and so, due to stale information, its performance is indirectly proportional to

mobility. It is also concluded that DSR is not very suitable for real-time traffic.

1

1. Introduction to MANET

1.1. Background

The next generation of wireless communication systems, needs a rapid deployment of

independent mobile users. Major examples include establishing survivable, efficient, dynamic

communication for emergency/rescue operations, disaster relief efforts, and military networks.

Such network scenarios cannot depend on centralized and organized connectivity, and can be

conceived as applications of MANETs. A MANET is an independent collection of mobile nodes

that communicate over comparatively bandwidth constrained wireless links. Since the nodes are

mobile, the network topology may change quickly and unpredictably over time. The network is

decentralized, where all network activity including discovering the topology and delivering

messages must be executed by the nodes themselves, i.e., routing functionality will be integrated

into mobile nodes.

1.2. Classification of Ad hoc Networks

As compared to wired networks, wireless networks have a unique capability of conducting

transmission without any wired links to the nodes. Nodes just have to be in each other‟s

transmission range. There are two categories of wireless networks, infrastructure based wireless

networks and infrastructure less or ad hoc wireless networks.

1.2.1. Infrastructure based wireless networks

Infrastructure networks have fixed network topology. Wireless nodes connect through a

fixed point known as base station or access point. Mostly, the access point or base station is

connected to the main network through a wired link. All of the wireless connections must pass

from the base station. If a node is in the range of several base stations, it will connect to any one

of those stations on the bases of some criteria [1], for example, communication quality or the

content of communication services.

2

1.2.2. Ad hoc wireless networks(infrastructure less)

An ad hoc wireless network is an autonomous system consisting of nodes, which may or

may not be mobile, connected with wireless links and without using pre-existing communication

infrastructure or central authority. Ad hoc networking is expected to play an important role in the

future of wireless mobile networks due to the widespread use of mobile and hand-held devices.

1.3. Overview of MANETs

MANET is a self-configuring network of mobile devices connected by wireless links.

Each device or node in a MANET is free to move by itself in any direction, and will

therefore change its links to other devices frequently. Each node must relay traffic, to another

node within its range, and therefore be a router. The most important challenge in building a

MANET is equipping each device, such that it can continuously maintain the information

required to properly route traffic.

Figure 1: MANET

A MANET can be a standalone network or it can be connected to external networks such as

the Internet.

MANETs are different from the traditional wired networks on the basis of some

characteristics; some of them are discussed below:

Limited bandwidth: Wireless links continue to have significantly lower capacity than their

hardwired counterparts [2]. In addition, the realized throughput of wireless communications,

after accounting for the effects of multiple access, fading, noise, and interference conditions, etc.,

is often much less than a radio‟s maximum transmission rate [2].

3

Dynamic topology: Nodes are free to move arbitrarily; thus, the network topology which is

typically multihop may change randomly and rapidly at unpredictable times, and may consist of

both bidirectional and unidirectional links.

Energy-constrained operation: Some or all of the nodes in a MANET may rely on batteries

or other exhaustible means for their energy. For these nodes, the most important system design

criteria for optimization may be energy conservation.

Limited physical security: Mobile wireless networks are generally more prone to physical

security threats than are fixed-cable networks. The increased possibility of eavesdropping,

spoofing, and denial-of-service attacks should be carefully considered.

Asymmetric Links: All nodes in a MANET do not have the same transmission range, and

therefore the links between them posses‟ asymmetric properties.

1.4. Issues in MANET

Some salient features that affect the design, deployment, and performance of MANET are as

follows:

Routing

Medium access scheme

Multicasting

Transport layer protocol

Pricing scheme

Quality of service provisioning

Self-organization

Security

Energy management

Addressing and service discovery

Scalability

Deployment considerations

4

1.5. Aims and Objectives

The objective for this thesis is to evaluate some of the proposed routing protocols for

MANET, based on performance. Furthermore, the following goals have been focused in the

thesis:

Get a general understanding of MANETs

Generate a simulation environment that could be used for analysis

Analyze some of the proposed routing protocols for MANETs

1.6. Thesis structure

This thesis consists of 6 chapters and two appendices. Chapter 1 enlightens the basic concept

of MANETs and its issues. Chapter 2 describes the different routing protocols. Chapter 3

describes the simulator used. Chapter 4 includes the performance analysis that has been done on

the protocols. Chapter 5 concludes the whole thesis and chapter 6 is the references that have been

used. The appendices contain the installation process of Linux and the simulator along with their

screen shots, the AWK program that has been used and the modified codes for protocols.

5

2. Mobile Ad hoc Routing Protocols

2.1. MANET Routing Overview

Routing is the most important aspect in ad hoc network since ad hoc network topology

frequently changes and multi-hop communication is required.

In MANET, routing is different from other networks and so it has its own protocols for

achieving the task of routing, some of them are invented primarily for MANETs, and some were

adapted from routing protocols in used wired networks. One of the most important targets of

these protocols is that they must be able to work with any topology, because MANET‟s topology

may change at any time.

The most important differences between MANETS and conventional networks with respect

to routing are:

Conventional networks are usually static. This is very different from Ad Hoc networks,

where the topology can be very different at different times and may change rapidly. In

conventional networks, all the routes can be known in advance. Whereas, in MANETs,

this is not always possible due to mobility and it is possible for each node to have the

route to reach all the other nodes.

In the MANETS it is not wise to overflow the routing information through the network.

This is in contrast to conventional networks where bandwidth is not limited.

Therefore it becomes clear that MANET routing protocols need to accomplish some goals

such as the followings:

1. Distributed operation: Conventional networks always worked in a centralized structure;

this does not exist in MANETS. Therefore, routing protocols need to work in a

decentralized network without any hierarchy operations are without structure and

decentralized.

2. Uni-directional links: Ad hoc routing protocols are designed with a wired network in

mind. However, in wired networks, links are assumed to be directional. In ad hoc

networks, this is not the case; differences in wireless networking hardware of nodes or

radio signal fluctuations may cause uni-directional links, which can only be traversed in

one direction.

6

3. Reactive approach: Protocols that follow a reactive approach have to provide the route

only when it is needed by the nodes. The problem related to this is that latency can be high

[3].

4. Proactive approach: With this approach the routing protocol must provide the capability

to create and maintain the routes in the routing tables continuously without introducing

high overhead [3].

2.2. Classification of Routing Protocols

Routing protocols can be classified into these categories depending on their properties

Proactive Routing Protocols

Reactive Routing Protocols

Hybrid Routing Protocols

2.2.1. Proactive Routing Protocols

For all protocols in this category (also called table-driven protocols), the route is already

available when one node wants to send data.

It does not matter that the nodes do not need the route at any particular time; they

continuously look for an available route. Therefore when the route is needed the information is

already available. The time interval at which a route advertisement broadcast is sent is important

because it will be a factor which will decide if the network has a good performance or there will

be higher overhead in the network. The nodes keep the current route information in two ways,

periodically when they do the route discovery and when they discover that any route has changed

even if they are not part of the route.

An advantage of proactive routing protocols is that when the nodes need the route, they

already have the information; hence it provides a very low latency and very good performance.

The problem arises when there is overhead in the network; due to routing packets,

because nodes require the available routes at all times. Routes which are not required are also

maintained. It can be concluded that the overhead is the main disadvantage for proactive routing

protocols [4].

Examples of proactive routing protocols are OLSR [5] or DSDV [6]

7

2.2.2. Reactive Routing Protocols

Reactive routing protocols (also called on-demand protocols) obtain routes only when

needed. When the node needs to send a packet, it will broadcast a route request. The nodes in its

transmission range will receive it and they will broadcast, and so on until some node has a route

to the destination or the route request is received by the destination. The nodes which have the

route to the destination or the destination itself unicasts a route reply towards the source node. In

this kind of protocols the nodes do not try to keep routing information if they do not need it.

An advantage of this approach is the overhead in the network is typically low. Therefore,

nodes save energy, bandwidth and memory. But as a disadvantage, these protocols have higher

route acquisition latency; because when they need a route it first needs to be discovered [4].

Examples of these protocols are AODV [7] or DSR [8].

2.2.3. Hybrid Routing Protocols

Both approaches (reactive and proactive) have advantages and disadvantages depending

on the characteristics of the networks. The hybrid routing protocols have been created to avoid

the disadvantages of the reactive and proactive protocols, but to get the advantages of both at the

same time.

In hybrid approach there are two different zones, the first one where the nodes are near

source node, proactive approach is followed the nodes will maintain the routing tables with the

neighbors within a determinate number of hops. In the other zone, the nodes far from the source,

the approach to get these nodes is reactive. [3].

Example of these protocols is ZRP [10].

2.3. Analysis of MANET Routing Protocols

The protocols that have been analyzed in this thesis are:

Ad hoc On-demand Distance Vector Routing

Destination Sequenced Distance Vector Routing

Dynamic Source Routing

Temporarily Ordered Routing Algorithm

8

2.3.1. Ad hoc On-demand Distance Vector Routing (AODV)

2.3.1.1. Description

The Ad hoc On-Demand Distance Vector(AODV) [7] routing protocol enables multi-

hop routing between participating mobile nodes wishing to establish and maintain an ad-hoc

network.

AODV is based upon the distance vector algorithm. It is a reactive protocol, it only

requests a route when needed and does not require nodes to maintain routes to destinations that

are not actively participating in the communication. As long as the end points of a

communication connection have valid routes to each other, AODV does not play any role.

Features of this protocol include loop freedom and that link breakages cause immediate

notifications to be sent to the affected set of nodes, but only that set. Additionally, AODV has

support for multicast routing and avoids the Bellman Ford "counting to infinity" problem [11].

The use of destination sequence numbers guarantees that a route is "fresh".

The algorithm uses various messages to discover and maintain links. Whenever a node

wants to find a route to another node, it broadcasts a Route Request (RREQ) to all its neighbors. The

RREQ circulates through the network until it reaches the destination or a node with a fresh

enough route to the destination. Then the route is created by unicasting a RREP back to the

source.

Figure 2: Ad hoc On-demand Distance Vector Routing Protocol

The algorithm uses hello messages (a special RREP) that are broadcasted periodically

to the immediate neighbors. If hello messages stop coming from a particular node, the neighbor

can assume that the node has moved away and mark that link to the node as broken and notify the

9

affected set of nodes by sending a link failure notification (a special RREP) to that set of nodes.

2.3.1.1.1. Route table management

AODV needs to keep track of the following information for each route table entry:

Destination IP Address: IP address of the destination node.

Destination Sequence Number: Sequence number of the destination.

Hop Count: Number of hops required to reach the destination.

Next Hop: The neighbor, which has been chosen to forward packets to the

destination for this route entry.

Lifetime: The time for which the route is available.

Active neighbor list: Neighbor nodes that are currently using this route entry.

Request buffer: Makes sure that a request is only used once.

2.3.1.1.2. Route discovery

A node broadcasts a RREQ when it needs a route to a destination and does not

have one already. This can happen if the route to the destination is unknown, or if a previously

valid route expires. After broadcasting a RREQ, the node waits for a RREP. If the reply is not

received within a certain time, the node may rebroadcast the RREQ or assume that there is no

route to the destination.

Forwarding of RREQs is done when the node receiving a RREQ does not

have a route to the destination. Therefore it rebroadcasts a RREQ. The node also creates a

temporary reverse route to the Source IP Address in its routing table with next hop equal to the IP

address field of the neighboring node that sent the broadcast RREQ. This is done to keep track

of a route back to the original node making the request, and might be used for the last RREP to

find its way back to the requesting node. The route is temporary in the sense that it is valid for a

much shorter time, than an actual route entry.

When the RREQ reaches a node that either is the destination node or a node with

a valid route to the destination, a RREP is generated and unicasted back to the requesting node.

While this RREP is forwarded, a route is created to the destination and when the RREP reaches the

source node, there exists a route from the source to the destination.

10

2.3.1.1.3. Route Maintenance

When a node detects that a route to a neighbor no longer is valid, it will eliminate

the routing entry and send a link failure message, a triggered route reply message to the

neighbors that are actively using the route, informing them that this route no longer is

available. For this purpose AODV uses an active neighbor list to monitor the neighbors that are

using a particular route. The nodes that receive this message will repeat this procedure. The

message will finally be received by the affected sources that can chose to either stop sending

data or requesting a new route by sending out a new RREQ.

2.3.1.2. Properties

The advantage with AODV compared to classical routing protocols like distance vector

and link-state is that AODV has very less number of routing messages in the network. This is

because of AODV‟s reactive approach. This advantage pays off when the topology is changing

often.

AODV routes in a more traditional sense as compared to DSR. The advantage with

a more traditional routing protocol in an ad-hoc network is that connections from the ad-hoc

network to a wired network like the Internet is most likely easier.

The sequence numbers that AODV uses represents the freshness of a route and is

increased when something happens in the surrounding area. The sequence numbers prevents

the formation of loops.

AODV only maintains one route for each destination. It uses hello messages at the IP-

level. The hello messages add a large overhead to the protocol.

AODV only supports bi-directional links and not the unidirectional links. When a

node receives a RREQ, it will setup a reverse route to the source by using the node that

forwarded the RREQ as next hop. This means that the route reply, in most cases is unicasted back

the same way as the route request used.

2.3.2. Destination Sequenced Distance Vector Routing (DSDV)


DSDV [6] is a hop-by-hop distance vector routing protocol. Each node has a routing

11

table that for all reachable destinations stores the next-hop and number of hops for that

destination. Like distance-vector, DSDV requires each node to periodically broadcast routing

updates. The advantage with DSDV over traditional distance vector protocols is that DSDV

assures loop-freedom.

Figure 3: Destination Sequenced Distance Vector

Table 1: DSDV Routing Table

Figure 4: Destination Sequenced Distance Vector

Table 2: DSDV Routing Table

Dest. Next

Hop

Metric Seq. No

N4 N4 0 S406_N4

N1 N2 2 S128_N1

N2 N2 1 S564_N2

N3 N2 2 S710_N3

N5 N6 2 S392_N5

N6 N6 1 S076_N6

N7 N6 2 S128_N7

N8 N6 3 S050_N8

Dest. Next

Hop

Metric Seq. No

N4 N4 0 S516_N4

N1 N6 3 S238_N1

N2 N2 1 S674_N2

N3 N2 2 S820_N3

N5 N6 2 S502_N5

N6 N6 1 S186_N6

N7 N6 2 S238_N7

N8 N6 3 S160_N8

12

Table 1 shows the routing table of DSDV before N1 changes its position, as N1

changes its position; the entries in the routing table are also changed, and can be seen in table 2.

To assure loop-freedom DSDV uses a sequence numbers to tag each route. The

sequence number represents the freshness of a route and routes with higher sequence numbers

are favorable. If the routes have the same sequence number then the one with a lower hop-count I

considered to be used. The sequence number is increased when a node N4 detects that a route to

a destination N1 has broken. So the next time node N4 advertises its routes, it will advertise the

route to N1 with an infinite hop-count and a sequence number that is larger than before.

DSDV essentially is distance vector with some adjustments to make it better suited

for ad-hoc networks. These adjustments consist of triggered updates that will take care of

topology changes in the time between broadcasts. To reduce the amount of information in these

packets there are two types of update messages defined: full and incremental dump. The full

dump carries all available routing information and the incremental dump only carries the

information that has changed since the last dump.

2.3.2.2. Properties

Because DSDV is dependent on periodic broadcasts it requires some time to converge

before a route can be used. This converge time can probably be considered negligible in a static

wired network, where the topology is not changing so frequently. On the other hand, in an ad-

hoc network, where the topology is very dynamic, this converge time will probably mean a lot of

dropped packets before a suitable route is detected. The periodic broadcasts add a lot of overhead

into the network.

2.3.3. Dynamic Source Routing (DSR)


Dynamic Source Routing (DSR) [8] [12] is also a reactive protocol. It allows nodes to

dynamically discover a route across multiple network hops to any destination. Source routing

means that each packet carries the complete ordered list of nodes through which the packet must

pass, in its header. DSR does not use periodic routing messages/router advertisements, and so it

reduces network bandwidth overhead, conserves battery power and avoids large routing updates

throughout the ad-hoc network. DSR relies on support from the MAC layer (the MAC layer

13

should inform the routing protocol about link failures). Route discovery and route maintenance

are the two basic modes of operation in DSR.

2.3.3.1.1. Route Discovery

Route discovery is the mechanism in which a node N1 wishing to send a packet to

N8, obtains the source route to N8. Node N1 requests a route by broadcasting a Route Request

(RREQ) packet. Every node receiving this RREQ searches through its route cache for a route to

the requested destination. DSR stores all known routes in its route cache. If no route is found, it

forwards the RREQ further and adds its own address to the recorded hop sequence. This request

propagates through the network until either the destination or a node with a route to the

destination is reached. When this happens, a Route Reply (RREP) is unicasted back to the

initiator. This RREP packet contains the sequence of network hops through which it may reach

the destination.

In Route Discovery, a node first sends a RREQ with the maximum propagation

limit (hop limit) set to zero, not allowing its neighbors to rebroadcast it. By using just a single

broadcast packet, this method allows a node to query the route caches of all its neighbors.

Nodes can also operate their network interface in promiscuous mode; the interface

address filtering is disabled and causes the network protocol to receive all packets that the

interface overhears. These packets are scanned for useful source routes or route error messages

and then they are discarded.

The route back to the initiator can be retrieved in several ways. The simplest way

is to reverse the hop record in the packet. Though, this assumes symmetrical links. In order to

deal with this, DSR checks the route cache of the replying node. If a route is found, it is used as

an alternative. Another way is to piggyback the reply on a RREQ targeted at the initiator. This

means that DSR can calculate correct routes in the presence of asymmetric (unidirectional) links.

Once a route is found, it is stored in the cache with a time stamp and the route maintenance

begins.

14

Figure 5: Dynamic Source Routing Protocol

2.3.3.1.2. Route Maintenance

Route maintenance is the mechanism by which a packet sender N1 detects if the

network topology has changed, lest the route to the destination N8 can no longer be in use. This

might happen because a host within a source route, moves out of wireless transmission range or

is powered off making the route unusable. A failed link is sensed by either actively monitoring

acknowledgements or passively by running in promiscuous mode, overhearing that a packet is

forwarded by a neighboring node.

When route maintenance senses a problem with a route in use, a route error

packet is sent back to the source node. When this error packet is received, the hop in error is

removed from this hosts route cache, and all routes that contain this hop are shortened at this

point.

2.3.3.2. Properties

DSR has an advantage of source routing. Intermediate nodes do not need to maintain

up-to-date routing information in order to route the packets they relay. There is also no need for

periodic routing advertisement messages, which leads to reduced network bandwidth overhead,

particularly when little or no significant host is moving. Battery power is also conserved on the

mobile hosts, both by not sending the advertisements and by not needing to receive them; a host

could go down to sleep as an alternative.

The key advantage of this protocol is that it learns routes by scanning for information

in packets that are received. A route from N1 to N8 through N2 means that N1 learns the route to

15

N8, but also that it will learn the route to N2. The source route will also mean that N2 learns the

route to N1 and N8 and that N8 learns the route to N1 and N2. This form of active learning

reduces overhead in the network, which is very good.

Each packet carries a slight overhead which contains the source route of the packet.

This overhead increases when the packet has to go through more hops to reach the destination.

So the packets sent will be somewhat bigger, because of the overhead.

Running the interfaces in promiscuous mode can be a serious security issue. As the

address filtering of the interface is turned off and all packets are scanned for information. A

potential intruder could listen to all packets and scan them for useful information such as

passwords and credit card numbers. Applications have to provide the security by encrypting their

data packets before transmission. The routing protocols are prime targets for impersonation

attacks and therefore they must also be encrypted.

2.3.4. Temporarily Ordered Routing Algorithm (TORA)


Temporally Ordered Routing Algorithm (TORA) [9] is a distributed routing protocol.

The core algorithm is one in a family referred to as link reversal algorithms. TORA is designed

to minimize the effect of topological changes. A key concept in its design is that control

messages are typically confined to a very small set of nodes. It guarantees that all routes are

loop-free, but temporary loops may form, and typically provides multiple routes for any

source/destination pair. It provides only the routing mechanism and depends on Internet MANET

Encapsulation Protocol (IMEP) [13] for other basic functions.

TORA can be divided into three basic functions: creating routes, maintaining routes,

and erasing routes. The creation of routes basically assigns directions to links in an undirected

network or portion of the network, building a directed acyclic graph (DAG) rooted at the

destination (See Figure 6).

TORA assigns a height to node in the network. All messages in the network flow

downstream, from a node with higher height to a node with lower height. Query (QRY) and

Update (UPD) packets are used to discover routes. When a node with no downstream links needs

a route to a destination, it will broadcast a QRY packet. This QRY packet will spread through the

16

network until it reaches a node that has a route to the destination or it is the destination itself.

Such a node will then broadcast a UPD packet that contains the node height. Every node

receiving this UPD packet will set its own height to a larger height than specified in the UPD

message. The node then broadcasts its own UPD packet. This will result in a number of directed

links from the originator of the QRY packet to the destination. This process may result in

multiple routes. Maintaining routes refers to reacting to topological changes in the network in a

manner such that routes to the destination are re-established within a finite time, meaning that its

directed portions return to a destination-oriented graph within a finite time. Upon detection of a

network partition, all links in the portion of the network that has become partitioned from the

destination are marked as undirected to erase invalid routes. Routes are erased by using clear

(CLR) messages.

Figure 6: Temporarily Ordered Routing Algorithm

17

2.3.4.2. Properties

A comparison made by the CMU Monarch project [12] has shown that the overhead

in TORA is quite large because it uses IMEP for some of its basic functions.

The graph is aimed at the destination, which has the lowest height. However, the

source originating the QRY does not necessarily have the highest height. This can lead to the

situation, where multiple routes are possible from the source to the destination, but only one

route will be discovered. The reason for this is that the height is initially based on the distance in

number of hops from the destination.

2.4. Comparison

As yet, the protocols have been analyzed theoretically. Table 3 summarizes and compares the

result from these theoretical analyses and shows which protocol has what property.

Table 3: Comparison of MANET Routing Protocols

AODV DSDV DSR TORA

Loop-free Yes Yes Yes No, (temporary loops)

Multiple routes No No Yes Yes

Distributed Yes Yes Yes Yes

Routing Philosophy Reactive Proactive Reactive Reactive

Unidirectional link

support

No No Yes No

QoS Support No No No No

Multicast Yes No No No

Security No No No No

Power conservation No No No No

Periodic broadcasts Yes (When

needed)

Yes No Yes (IMEP)

Requires reliable or

sequenced data

No No No Yes

Routing Metric Freshest &

shortest path

Shortest

path

Shortest

path

Shortest

path

18

The only proactive protocol in this comparison is DSDV. It is the most similar protocol to

traditional routing protocol in wired networks. The addition of sequence numbers ensures loop-

free routes. DSDV will probably be good enough in networks, with low mobility. The authors of

DSDV reckoned the same and designed AODV, which is a reactive version of DSDV. They also

added multicast capabilities, which will enhance the performance considerably when one node

communicates with several nodes. The reactive approach in AODV has many similarities with

that of DSR. They both have a route discovery mode that uses request messages to find new

routes. The difference is that DSR is based on source routing and will learn more routes than

AODV. DSR also has the advantage that it supports unidirectional links. DSR has however one

major drawback and it is the source route that must be carried in each packet, causing an increase

in overhead. This can be quite costly, especially when considering QoS and also when there are a

lot of nodes. AODV can connect to the internet more easily, as compared to DSR because of its

traditional routing.

It can be concluded that none of these protocols take smart routing decisions when a

networks goes through high traffic load. Since the route selection factor used by these protocols

are metrics such as the shortest hop count and the fastest response time to a request, it might lead

to a situation where all the traffic gets routed through the same route even if there are other

routes available with lesser traffic load.

19

3. Simulation Environment

3.1. Network Simulators Overview

There are several simulation programs that can be used for the simulation. According to a

survey carried out in 2005, the simulator utilization rate are as seen in Figure 7 in the form of a

pie chart, in which each segment represents a particular simulator. From this figure, the three

most popular simulators, NS-2 (39%), GloMoSim (21%), and OPNET (9%), accounted for more

than 2/3 of the simulators used. NS-2, GloMoSim, and OPNET are highly modular discrete event

simulators. These simulators are provided for simulating the behavior of networks in a complex

network topology [14]. For this thesis, a survey was carried out to find the best suitable

simulator, based on the following criteria:

How difficult is the installation?

How frequent is the simulator used in research-papers regarding MANETs?

Is it open source?

Which protocols does it support?

How user friendly is it?

How well is its documentation?

Figure 7: Simulators Utilization Trend

20

3.1.1. Network Simulator-2

This simulator is probably the most commonly used software of the four. Network

Simulator 2 [15], also called NS-2, is developed by ISI, the Information Sciences Institute at the

USC School of engineering. The source code is free of charge. There is a comprehensive manual

for the installation and use of the software on the NS-2 homepage [16].

The software is mostly text-based and can be complicated to use if the user is not familiar

with Unix-commands. Some parts are managed with GUIs, which makes it easier to understand

the happenings.

NS-2 (now NS-3) is constantly under development and its progress can be monitored on its

homepage. There is also a bug report forum where users can report any problems and bugs they

encounter while using NS-2. In addition to these features there are also a FAQ and the possibility

to sign up to different ns-related mailing lists.

3.1.2. GloMoSim

GloMoSim stands for Global Mobile information systems Simulation library and

supports protocols for a purely wireless network [17]. It‟s developed at UCLA Parallel

Computing Laboratory (UCLA PCL) and is intended for academic institutions for research

purposes. The current version, GloMoSim 2.0 (December 2000), can be downloaded from the

GloMoSim homepage if you are within the „edu‟ domain. If commercial users want to use

GloMoSim they‟ll have to obtain the commercial version called QualNet. This version is

extended in some areas. You can read more about it in section 3.1.3.

In order to get GloMoSim to work you will need the latest Parsec Compiler (included

with the GloMoSim distribution), Parsec is a C-based simulation language developed by PCL at

UCLA. There is very little documentation of the installation procedure, which is poorly

described. If the user runs into trouble while installing, the documentation would not be of much

use.

Protocols supported by GloMoSim are AODV, Bellman-Ford, DSR, Fisheye, LAR,

ODMRP and WRP. Developing one‟s own protocols in GloMoSim is possible. But to do so the

user should have some familiarity with Parsec. Although the code to the protocols will be written

21

purely in C code, with some Parsec functions for time management, Parsec compiler will be

needed.

Although there are some papers in which GloMoSim have been used, it‟s not as

frequently used as NS-2. Also there is no FAQ, forum or a mailing list on the homepage.

3.1.3. QualNet

QualNet is a software for network simulations, developed by SNT (Scalable Network

Technologies). SNT claims that QualNet can be used for designing a network or network device

to optimize it, saving time and money [18].

The QualNet software consists of five tools plus integration modules and model libraries.

QualNet Animator allows for graphically designing the network model (using a wide library of

components) and can be used to display the simulation as it runs or later on. QualNet Designer

allows users to generate code for their own protocol from scratch and make special statistic

reports. Adjustments can be made to already defined protocol models. QualNet Analyzer is a

graphic tool that presents statistics of different experiments in graphs.

The QualNet model library is a large library of networking options and contains the

MANET library. It includes models for providing wireless dynamic routing, shadowing, fading,

mobility, detailed physical layer effects such as steerable directional antennas and complex

modulation schemes. Routing protocols provided are AODV, BRP, DSR, DYMO, Fisheye,

IARP, IERP, LAR, OLSR, STAR, ZRP and ODMRP.

Documentation and help can be found at their homepage [18]. There are manuals as well

as a FAQ and a forum. Users can also get support by emailing or phoning SNT.

QualNet‟s customers include companies like Microsoft and Boeing and it is used by the

military. There are also some publications done featuring QualNet as the simulation tool.

3.1.4. OPNET

OPNET is a simulation tool that is developed by OPNET Technologies Inc. They are a

leading provider of management software for networks and applications. OPNET have a number

solutions that aims to help the customer in different areas like, application performance

troubleshooting, application deployment planning, network configuration auditing, network

capacity and resiliency planning and network technology R&D.

22

For simulating a MANET, OPNET provides a software platform called the OPNET

Modeler. This software also contains a large number of different models for simulating network

protocols, technologies and applications. There is a wireless model included that provides these

routing protocols AODV, DSR, OLSR, OPSF and TORA.

Although OPNET is rather intended for companies to diagnose and organize their

networks, individual users can develop and implement their own protocol or modify existing

implementations of standard protocols.

The software tends to be well documented and there shouldn‟t be any problems either

with the installation or support. On the homepage [19] there are technical resources with a FAQ

and product updates as well as a forum for OPNET users. To be able to participate in the forum

and download the documents you have to have a license since they are protected by passwords.

On the negative part the software is very expensive and not easy to obtain for single individuals.

3.2. Choice of Simulator

When choosing a simulation program the question of what you want to simulate and which

resources you have to conduct these simulations are of key importance. The simulation work for

this thesis can be done on any of these four simulators. But due to time limitation and the

available backup provided, the choice was quite limited.

The question also arises of how much open source code that is publicly available. This is an

important factor since time is limited and implementing a protocol or writing the simulation code

will require a lot of time.

GloMoSim is available for downloading only if your IP address resolves to an academic

domain name. The documentation isn‟t very good and it seems to be hard to get any kind of

support. Although some papers have used GloMoSim to simulate MANET protocols, the

question is how to compare results with those who have used other simulators.

NS-2 is free to download and researchers for simulating MANETs commonly use it. It has an

extensive manual and some support in the mailing list. New features are developed continuously

and added functions for protocols are available for downloading.

Altogether the choice of simulation program is quite clear; NS-2 provides the best overall

solution.

23

3.2.1. NS-2 Working Flow

Figure 8 shows a block diagram of the working flow of NS-2.

The mobility pattern file specifies the initial position and the gradual movement of the

nodes. The connection pattern file specifies the traffic flow and how the nodes are connected.

These two files are embedded into the Tcl script, which subsequently runs on an NS-2. This Tcl

file creates two output files: NAM file and trace file. The NAM file contains the visual animation

of the scenario and can be viewed on the network animator (NAM). The trace file contains the

operations of a simulation represented as a chronological sequence of events. Each event occurs

at an instant in time.

Trace file contains raw data and AWK is used to extract useful data from them e.g. delay,

overhead, throughput etc. After having the information in the appropriate format, to plot the

result graphs is the last task for obtaining the information to evaluate the simulations. The graphs

are used to examine and compare the results of different simulation scenarios.

Figure 8: NS-2 Working Flow

3.2.1.1. Network Animator

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. Visualization of mobile nodes can be viewed as animations on NAM.

Figure 9 shows the animation of a MANET with 25 nodes.

24

Figure 9: Screen Shot of Network Animator

3.2.1.2. Tool Command Language

Tcl is a scripting language which provides interfacing with C++ objects such as

agents, protocols, links, queues etc.

In the beginning of a Tcl file, variables are defined and can be seen in the code below:

1. set val(chan) Channel/WirelessChannel

2. set val(prop) Propagation/TwoRayGround

3. set val(netif) Phy/WirelessPhy

4. set val(mac) Mac/802_11

5. set val(ifq) Queue/DropTail/PriQueue

6. set val(ll) LL

7. set val(ant) Antenna/OmniAntenna

8. set val(x) 1000 ;# X dimension of the topography

9. set val(y) 1000 ;# Y dimension of the topography

10. set val(ifqlen) 50 ;# max packet in ifq

11. set val(seed) 1.0

12. set val(adhocRouting) AODV

13. set val(nn) 25 ;# how many nodes are simulated

14. set val(cp) "/root/ns-allinone-2.33/ns-

2.33/tcl/mobility/scene/aodv/cp/aodv-00-15-3"

25

15. set val(sc) "/root/ns-allinone-2.33/ns-

2.33/tcl/mobility/scene/aodv/sc/aodv-00-15-3"

16. set val(stop) 600.0 ;# simulation time

In the main program, first of all, the global variables are initialized:

17. set ns_ [new Simulator]

18. set topo [new Topography]

19. set tracefd [open aodv-00-15-3.tr w]

20. set namtrace [open aodv-00-15-3.nam w]

21. $ns_ trace-all $tracefd

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

A simulator instance is being created in line 17, line 18 sets up a topography object.

Line 19, 20, 21 and 22 creates trace object for NS and NAM.

23. $topo load_flatgrid $val(x) $val(y)

24. set god_ [create-god $val(nn)]

In line 23 a new topology instance is being defined as a flat grid of area „x‟ meters x

„y‟ meters, the values of „x‟ and „y‟ are defined in the beginning.

Line 24 creates a God instance. The number of wireless nodes is passed as an

argument. It is used to create a matrix to store connectivity information of the topology.

The next code will define how nodes should be created:

25. $ns_ node-config -adhocRouting $val(adhocRouting) \

26. -llType $val(ll) \

27. -macType $val(mac) \

28. -ifqType $val(ifq) \

29. -ifqLen $val(ifqlen) \

30. -antType $val(ant) \

31. -propType $val(prop) \

32. -phyType $val(netif) \

33. -channelType $val(chan) \

34. -topoInstance $topo \

35. -agentTrace ON \

36. -routerTrace ON \

37. -macTrace OFF

26

Line 25 – 37 defines the global node setting; the variables defined in the beginning

are being called in this section.

38. for {set i 0} {$i < $val(nn) } {incr i} {

39. set node_($i) [$ns_ node]

40. $node_($i) random-motion 0 ;# disable random motion

41. }

Line 38 – 41 creates the specified number of nodes [$val(nn)] and "attach" them to

the channel.

42. puts "Loading connection pattern..."

43. source $val(cp)

44. puts "Loading scenario file..."

45. source $val(sc)

Line 42 and 43 defines the node movement model, whose path is provided in the

beginning. Line 44 and 45 defines the traffic model whose path is also provided in the beginning.

46. for {set i 0} {$i < $val(nn)} {incr i} {

47. $ns_ initial_node_pos $node_($i) 20

48. }

Line 46 – 48 defines the initial position of the nodes in NAM.

49. for {set i 0} {$i < $val(nn) } {incr i} {

50. $ns_ at $val(stop).0 "$node_($i) reset";

51. }

52. $ns_ at $val(stop).0002 "puts \"NS EXITING...\" ; $ns_ halt"

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

$val(adhocRouting)"

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

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

56. puts "Starting Simulation..."

57. $ns_ run

Line 49 – 57 tells the nodes when the simulation ends.

27

3.2.1.3. Trace File Format

The trace file provides traces of all the events that occurred during the simulation in a

chronological sequence. Each event occurs at an instant in time.

The trace file format used in this thesis is the „old wireless trace format‟. The traces in

a trace file may look like this:

s 100.691175361 _13_ RTR --- 758 cbr 532 [0 0 0 0] ------- [13:1 14:0 30 8] [17] 0 3

r 100.694465925 _11_ AGT --- 757 cbr 532 [13a b 12 800] ------- [9:3 11:0 29 11] [64] 2 2

r 100.700628759 _8_ RTR --- 758 cbr 532 [13a 8 d 800] ------- [13:1 14:0 30 8] [17] 1 3

f 100.700628759 _8_ RTR --- 758 cbr 532 [13a 8 d 800] ------- [13:1 14:0 29 19] [17] 1 3

It can be seen that the variables are separated by spaces. Figure 10 explains the

format:

Figure 10: Old Wireless Trace File Format

Some variables are further explained as follows [20]:

The operation performed can be of four types:

o s = send

o r = receive

28

o f = forward

o D = drop

Service of the node or the trace level can be

o AGT = agent

o RTR = router

o MAC = media access control

The different reasons for dropping a packet are given below:

o END = end of simulation

o COL = MAC collision

o DUP = MAC duplicate

o ERR = MAC packet error

o RET = MAC retry count exceeded

o STA = MAC invalid state

o BSY = MAC busy

o NRTE = no route is available

o LOOP = there is a routing loop

o TTL = time to live has reached zero

o TOUT = packet has expired

o CBK = MAC callback

o IFQ = no buffer space in IFQ

o ARP = dropped by ARP

o OUT = dropped by base stations on receiving routing updates from nodes

outside its domain

3.2.1.4. AWK Script

The word AWK is derived from the names of its inventors (Aho Weinberger and

Kernighan).

AWK is a C-like-programming language designed to search files for lines (or other

units of text) that contain certain patterns, either in files or data streams.

The raw data contained in trace files can be processed using AWK to extract useful

data, such as throughput, jitter, packet loss ratio, end to end delay etc.

29

The structure of an AWK script contains three sections:

BEGIN

Pattern

END

The BEGIN section executes only one time i.e.in the beginning of the script. Usually,

variables are defined in this section, if a user wants to print a heading; it could be done in this

section too.

As the name says, the pattern section contains the pattern that the user is looking for,

in a particular file or data stream. This pattern executes throughout the file. The functions

defined in this section are executed on one line at a time.

The END section also executes only once i.e. in the end. This section usually contains

printf functions and final calculations.

Consider the following input data stream:

s 100.691175361 _13_ AGT --- 758 cbr 532 [0 0 0 0] ------- [13:1 14:0 30 8] [17] 0 3

r 100.694465925 _11_ AGT --- 757 cbr 532 [13a b 12 800] ------- [9:3 11:0 29 11] [64] 2 2

r 100.700628759 _8_ RTR --- 758 cbr 532 [13a 8 d 800] ------- [13:1 14:0 30 8] [17] 1 3

f 100.700628759 _8_ RTR --- 758 cbr 532 [13a 8 d 800] ------- [13:1 14:0 29 19] [17] 1 3

And an AWK script which calculates sent packets:

BEGIN{

printf (“Sent Packets:”);

Sent=0;

}

{

if (( $1 == "s") && ($7 == “cbr”) && ($4=="AGT" ))

{ sent++; }

}

END{

printf ( “Sent Packets = %d,\n”, sent);

}

30

After running this AWK script on the data stream, the output would be:

Sent Packets:

Sent Packets = 1

31

4. Performance Analysis

4.1. Simulation Parameters

As scenario is a very crucial part of the simulation, 5 instances were created for each

scenario. The result was then compiled using average of those 5 instances. The simulation

parameters that have been used for the simulations are shown in Table 4.

It can be seen that the maximum speed, the pause time and the protocols have been varied.

Parameter Value

Transmission Range of each node 250 m

Total Nodes 25 nodes

Maximum Connections 15 connections

Data Rate 11 Mbps

Packet Rate 1 Packet/sec

Node Speed 2, 15, 30 and 45 m/s

Pause Time 0, 15, 30, 45 and 100 sec

Traffic Type Constant Bit Rate (CBR)

Routing Protocols AODV, DSDV, DSR and TORA

Propagation Model Random WayPoint

Queue Type Droptail

Simulation Time 600 sec

Area Size 1000 x 1000 m

Packet Size 512 bytes

Initial Node Placement Random

NS-2 version NS-2.29 and NS-2.33

Table 4: Simulation Parameters

32

4.2. Performance Analysis Factors

Before going into the actual simulation results, the factors to be measured when comparing

routing protocols in MANET are described. The performance analysis is based on the following

factors as a function of maximum speed and pause time:

End to End Delay

o It is the time taken by a packet to reach the destination

o It is preferred low

Normalized Routing Load

o It is a ratio of network control packets to all delivered packets


Packet Loss Ratio

o It is the ratio of sent packets to those not received at their destinations


Routing Overhead

o It is the number of routing packets


Packet Delivery Fraction (PDF)

o The ratio of the data packets delivered to the destinations to those generated

by the CBR sources

o It is preferred high

4.3. Simulation Results

The results obtained during the simulation are depicted in this section. The protocols that

have been simulated are DSDV, AODV, DSR and TORA, to compare how much better/worse

these protocols perform in different scenarios.

The simulations were conducted on a Dell Latitude E5500 Laptop with an Intel® Core™ 2

Duo processor at 2.4 GHz, with 2 Gigabytes of RAM.

In these simulations there are four types of different scenarios used, based on the maximum

speed of the nodes. The results will conclude how each protocol performs in the different

scenarios. The simulation results on the basis of chosen factors can be seen as follows:

33

4.3.1. End to End Delay

End to End Delay

Max. Speed 2 m/s

Pause Time AODV DSDV DSR TORA

0 0.110 0.066 0.260 0.358

15 0.084 0.048 0.640 0.418

30 0.070 0.042 0.552 0.334

45 0.214 0.044 0.514 0.670

100 0.172 0.054 0.730 0.364

Max. Speed 15 m/s


0 0.254 0.232 1.544 0.764

15 0.378 0.150 1.038 1.392

30 0.388 0.178 2.078 0.880

45 0.490 0.090 1.562 1.108

100 0.404 0.088 1.080 1.094

Max. Speed 30 m/s


0 0.452 0.256 1.658 0.972

15 0.352 0.248 1.896 1.486

30 0.466 0.302 2.376 1.642

45 0.482 0.226 1.616 1.450

100 0.466 0.146 2.568 1.710

Max. Speed 45 m/s


0 0.438 0.208 1.134 1.682

15 0.570 0.510 1.738 1.306

30 0.588 0.310 2.192 1.558

45 0.710 0.370 3.170 1.590

100 0.536 0.108 2.392 1.368

Table 5: Simulation Results: End to End Delay

34

Graph 1: End to End Delay [2 m/s]




End-to-end delay of data packets includes all possible delay caused by buffering during

route discovery latency, transmission delays at the MAC, queuing at interface queue, and

propagation and transfer time. Among these four protocols, DSDV has the least average end-to-

end delay. DSDV is a proactive protocol and the advantage of being one is that a path to a

destination is immediately available, so it experiences no delay for route discovery, when an

application needs to send a packet.

DSR is a source routing protocol, therefore it has longer delay because its route

discovery takes more time as every intermediate node tries to extract information before

forwarding the reply, throughout the path. Hence, while source routing makes route discovery

more profitable, it slows down the transmission of packets. This is the reason why AODV

performs better than two other reactive protocols in general.

35

4.3.2. Normalized Routing Load

Normalized Routing Load

Max. Speed 2 m/s


0 0.654 0.318 0.328 3.172

15 0.686 0.302 0.448 3.784

30 0.738 0.282 0.382 3.634

45 0.960 0.314 0.356 3.158

100 1.012 0.310 0.446 3.890

Max. Speed 15 m/s


0 2.148 0.570 1.544 7.236

15 2.236 0.620 1.174 10.188

30 2.240 0.640 1.708 8.346

45 2.322 0.562 1.558 8.622

100 1.854 0.548 1.006 8.500

Max. Speed 30 m/s


0 3.140 0.806 2.084 10.900

15 2.834 0.960 2.270 12.658

30 2.884 0.876 2.116 12.442

45 2.922 0.822 1.764 12.306

100 2.528 0.598 1.538 10.094

Max. Speed 45 m/s


0 3.884 0.950 2.948 15.128

15 3.698 1.180 2.540 14.032

30 3.554 1.190 2.590 12.220

45 3.148 1.008 2.520 12.296

100 2.672 0.684 1.970 7.588

Table 6: Simulation Results: Normalized Routing Load

36

Graph 5: Normalized Routing Load [2 m/s]




The results show that TORA has the highest normalized routing load; this is because

TORA uses IMEP for its basic functions. DSDV being a proactive protocol enjoys the advantage

of having the lowest normalized routing load, because proactive routing protocols do not need

too much routing packets.

The normalized routing load of AODV is higher than DSR, because AODV periodically

broadcasts hello messages and DSR does not.

The normalized routing load of TORA increases drastically as the mobility is increased,

whereas, in the case of AODV and DSR, it increases slightly.

37

4.3.3. Packet Loss Ratio

Packet Loss Ratio

Max. Speed 2 m/s


0 7.010 27.850 4.720 19.823

15 10.440 25.130 10.550 24.573

30 9.330 21.570 5.680 20.155

45 18.990 25.640 4.890 21.955

100 21.540 29.910 10.430 23.453

Max. Speed 15 m/s


0 14.110 43.350 6.540 21.221

15 15.190 47.150 4.950 30.683

30 15.890 50.180 12.170 25.712

45 19.830 44.140 11.160 30.449

100 20.390 46.490 7.930 32.025

Max. Speed 30 m/s


0 14.760 52.690 6.170 26.575

15 14.960 59.160 7.310 34.059

30 17.080 57.130 8.550 35.465

45 20.320 56.960 8.230 35.795

100 25.790 48.030 14.530 35.780

Max. Speed 45 m/s


0 17.260 60.740 4.980 31.626

15 18.160 65.040 7.320 31.173

30 21.640 65.450 7.380 33.052

45 23.170 62.040 11.030 36.687

100 27.650 51.820 16.950 34.362

Table 7: Simulation Results: Packet Loss Ratio

38

Graph 9: Packet Loss Ratio [2 m/s]




DSR has the lowest packet loss ratio because it stores the information of multiple paths,

whereas AODV does not. Whenever a link breaks AODV broadcasts a route request and waits

for some time to get new information by receiving a route reply; during this time AODV will

queue the packets, which are sometimes dropped because of expiration in the AODV queue. But

DSR will send the packets through an alternate path.

DSDV has the highest packet loss ratio because, being a proactive protocol, it sends

packets even before the routing tables have had enough time to converge and so the packets are

dropped, because it sends packets on a broken route that is listed as valid in its routing table.

Majority of dropped packets in TORA are due to routing loops, and it increases with the

increase in mobility.

39

4.3.4. Routing Overhead

Routing Overhead

Max. Speed 2 m/s


0 4922.6 1853.6 2396.2 20569.0

15 4973.8 1838.0 3113.2 21338.4

30 5194.6 1776.8 2906.6 22665.8

45 6224.0 1885.8 2725.2 19167.8

100 6364.2 1749.8 3205.2 23126.4

Max. Speed 15 m/s


0 14877.0 2618.2 11633.4 45000.4

15 15402.0 2644.2 9072.6 51545.2

30 15199.6 2580.2 12159.6 48791.6

45 15091.6 2517.4 11285.8 47144.0

100 11928.4 2364.2 7532.0 46046.4

Max. Speed 30 m/s


0 21682.6 3059.6 15813.8 64271.2

15 19475.2 3163.2 16962.8 65920.2

30 19413.8 2987.6 15627.4 62297.2

45 18793.2 2848.2 13139.6 62582.2

100 14829.8 2499.8 10617.0 49306.0

Max. Speed 45 m/s


0 26147.4 3030.6 22788.2 81468.6

15 24290.6 3342.8 19151.2 76536.0

30 22514.4 3320.4 19424.6 64518.6

45 19400.6 3074.8 17403.4 61352.2

100 15530.8 2568.2 13110.8 38457.6

Table 8: Simulation Results: Routing Overhead

40

Graph 13: Routing Overhead [2 m/s]




TORA has high routing overhead because IMEP‟s feedback loops cause heavy

congestion and it increases significantly with the increase in mobility.

AODV has more routing overhead than DSR because route discoveries usually propagate

to every node in the network. DSR uses routing cache aggressively, and maintains multiple

routes per destination.

Routing overhead in DSDV is more or less constant. This is due to the tremendous

overhead incurred by DSDV when exchanging routing tables.

41

4.3.5. Packet Delivery Fraction (PDF)

Packet Delivery Fraction

Max. Speed 2 m/s


0 92.938 72.140 95.234 79.546

15 89.398 74.764 89.294 72.428

30 80.422 78.326 94.232 77.322

45 80.848 74.286 88.492 76.406

100 78.276 69.994 89.362 74.776

Max. Speed 15 m/s


0 85.788 56.660 93.138 78.180

15 84.510 52.812 94.802 68.122

30 84.002 49.770 87.538 72.964

45 80.008 55.864 91.558 67.450

100 79.168 53.476 91.866 65.842

Max. Speed 30 m/s


0 85.108 47.324 93.654 72.656

15 84.894 40.852 92.472 64.814

30 82.704 42.842 91.088 63.060

45 79.460 43.016 88.646 63.248

100 73.720 51.950 85.072 61.368

Max. Speed 45 m/s


0 82.668 39.260 94.948 68.084

15 81.644 34.974 92.586 67.902

30 78.070 34.568 92.456 65.598

45 76.438 37.916 88.646 61.790

100 71.866 48.170 82.590 63.464

Table 9: Simulation Results: Packet Delivery Fraction

42

Graph 17: Packet Delivery Fraction [2 m/s]




DSDV‟s packet delivery fraction (PDF) is very less due to stale routing information. If a

node using DSDV is transmitting data and link failure occurs, it queues the packets until it gets a

new path for the desired destination. Node starts to drop the packets if the queue is full, and

happens frequently at high mobility. Also, as the node‟s speed increases, the difference in PDF

becomes bigger; this is because as speed increases, the probability of link failure increases.

AODV broadcasts a route request immediately in case of a link failure, and so its PDF is

quite better as compared to DSDV.

DSR on the other hand uses alternate path that it has saved during route discovery, and so

enjoys a higher PDF.

TORA has comparatively less PDF than AODV and DSR, due to the reason that it drops

a lot of packets as a result of routing loops.

43

5. Conclusion

5.1. Summary

In the previous chapter, the performance analysis was done, which brings out these

comparative results:

Factors Best to Worse Performer

End to End Delay DSDV AODV TORA DSR

Normalized Routing Load DSDV DSR AODV TORA

Packet Loss Ratio DSR AODV TORA DSDV

Routing Overhead DSDV DSR AODV TORA

Packet Delivery Fraction DSR AODV TORA DSDV

Table 10: Comparison of MANET Routing Protocols (on the basis of results)

The results are summarized as follows:

The fraction of packets received for AODV is in a range of 70-100%, and for DSR, it

is in a range of 80-100%, this is because they have link layer support for link

breakage and so they are much more stable. Whereas DSDV highly depends on

periodic broadcasts and so it shows a rather poor result, not even 50% of the packets

are received when mobility is increased.

In case of a higher traffic load, congestion will occur and packets will be dropped. So

if the routing protocol is fast enough in finding a route, the packets will have to spend

less time in a buffer, which will result in a smaller probability of packet drops. DSDV

would perform very well in such cases, but the overhead of AODV and DSR would

definitely increase.

The overall performance of DSDV decreases as mobility is increased, because of

stale information in its routing tables.

44

DSR performs better over AODV and TORA, because it has source routing, and it

stores multiple paths, so that it may react instantly in case of a broken route.

It is also observed that DSR has higher end to end delay, and that makes DSR not

very suitable for real-time traffic.

5.2. Future Work

Mobile ad-hoc networks are of increasing interest in a lot of applications, such as

collaborative computing, sensing networks, potential fourth generation wireless systems, and

reaction to incidents that destroyed the existing communication structure. There is much research

going on and there are yet many issues that could be subject to further studies.

Some of them are:

Simulator Environment: Using an improved simulator environment, e.g. by using

more protocols (e.g. ZRP), by varying number of nodes, by varying transmission

range etc.

Security: It is an important issue, as routing protocols are prime targets for

impersonation attacks, and MANETS are formed without any centralized authority.

TCP Variants: As TCP is optimized for wired links, it is not suitable for MANETs;

therefore its variants are designed such that they can use the bandwidth efficiently.

Quality of Service: the needs for Quality of Service can be taken under concern,

considering what purpose the network is created for.

Energy Management: It is an essential requirement for the efficient operation of the

battery powered MANETs.

The field of MANETs is rapidly on the rise and changing, and while there are yet many

challenges that need to be met, it is likely that such networks will see widespread use in a few

years time.

45

6. References

[1] K. Leung, et. al., “Transmission Control Protocol (TCP) in wireless Networks: issues,

approaches and challenges”. IEEE Communications Survey, Vol. 8 No. 4, pp. 64-79, 4th

October 2006.

[2] http://www.ietf.org/rfc/rfc2501.txt

[3] Björn Wigerg, et. al., “Porting AODV-UU Implementation to NS-2 and Enabling Trace-

Based Simulation”. Uppsala University, December 2002.

[4] C.Siva Murthy, et. al., “Ad Hoc Wireless Networks Architectures and Protocols”.

Published May 24, 2004 by Prentice Hall.

[5] http://www.ietf.org/rfc/rfc3626.txt

[6] Charles Perkins, et. al., “Highly dynamic destination-sequenced distance vector routing

(DSDV) for mobile computers”.

[7] Charles Perkins, et. al., “Ad-hoc On-Demand Distance Vector Routing”. In Proceedings

WMC-SA ‟99, Second IEEE Workshop on Mobile Computing Systems and Applications,

pp.90-100, Feb 1999.

[8] D. Johnson, et. al., “Dynamic Source Routing in Ad Hoc Wireless Networks”. Computer

Communication Review – Proceedings of SIGCOMM „96, Aug. 1996.

[9] V. D. Park, et. al., “A Highly Adaptive Distributed Routing Algorithm for Mobile Wireless

Networks,” Proc. INFOCOM ‟97, Apr. 1997.

[10] Haas, J., 1997, “A new routing protocol for the reconfigurable wireless networks”, Proc. of

IEEE 6th International Conference on Universal Personal Communications 97, pp. 562–

566.

[11] http://wiki.uni.lu/secan-lab/Count-To-Infinity+Problem.html

[12] Josh Broch, et. al., “A Performance Comparison of Multi-hop wireless Ad hoc Network

Routing Protocols”. Mobicom ‟98, Dallas Texas, 25-30 October, 1998.

[13] M. S. Corson, et. al., “Internet MANET Encapsulation Protocol (IMEP) Specification”.

Internet Draft draft-ietf-manet-imep-spec-01.txt

46

[14] C. R. Dow, et. al., “A Study of Recent Research Trends and Experimental Guidelines in

Mobile Ad-hoc Networks”. Proceedings of the 19th International Conference on Advanced

Information Networking and Applications (AINA‟05).

[15] http://www.isi.edu/nsnam/ns/

[16] http://www.isi.edu/nsnam/ns/ns-documentation.html

[17] http://pcl.cs.ucla.edu/projects/glomosim/

[18] http://www.scalable-networks.com/products/qualnet/

[19] http://www.opnet.com/

[20] http://www.isi.edu/nsnam/ns/doc/node186.html

47

7. Appendix A

7.1. Installation Process of Linux

7.1.1. Introduction to VMware Workstation

Virtual Machine ware (VMware) allows multiple standard operating systems and their

applications to run with high performance in secure and transportable virtual machines. Each

virtual machine is equivalent to a PC with a unique network address and full complement of

hardware choices.

Figure 11: Screen Shot of VMware Workstation

7.1.2. Creating new Virtual Machine

A new virtual machine can be created by clicking the icon shown in the figure below:

Figure 12: Screen shot of New Virtual Machine Icon

It is optional whether you install the operating system using a CD or an iso image.

48

Figure 13: Screen Shot of New Virtual Machine Wizard 1

As Cent OS is not a pre defined system in VMware, Red Hat Enterprise Linux 5 is used

as an equivalent.

Figure 14: Screen Shot of New Virtual Machine Wizard 2

Chose the disk size you want to assign to this particular machine and power it on, the

following screen will appear.

49

Figure 15: Screen Shot of CentOS Installation 1

The machine will now load the iso image… and installation of the operating system will

start.

Click next and follow instructions.


50

Choose „Customize now‟ and click next.

Select the following packages:

Desktop Environment:

o Gnome desktop environment

o KDE desktop environment

Applications:

o Editors

o Emacs

o Engineering and scientific

o Games and entertainment

o Graphical and internet

o Office/productivity

o Sound and video

Figure 17: Screen Shot of CentOS

Installation 3


Installation 4


Installation 5


Installation 6

51

o Text based internet

Development:

o Development libraries

o Development tools

o Gnome software development

o KDE software development

o Legacy software development

o Ruby software development

o X- software development

Server:

o Printing support

Base System:

o Base

o Dial-up network support

o X-window support

And none from Clustering, Cluster storage and Languages

Click next and continue.


52



Now chose a user name and its password.

CentOS 5.3 is now installed.

7.1.3. Installing VM Tools

Power the virtual machine on, and on the VMware Workstation click on VMInstall

VM Tools… and follow these instructions.

Figure 24: Screen Shot of VM Tools Installation

53

An icon for VM Tools will appear on the desktop

Figure 25: Screen Shot of VM Tools Icon

Extract the tar.gz file from this CD, and the place the folder in root home

Now go to vmware-tools-distrib folder and run the file vmware –install.pl as

follows:

o [root@localhost vmware-tools-distrib]# ./vmware-install.pl

This will install VM tools, now log out and log in again…

The VM Tools are now active.

7.2. Installation Process of Network Simulator

7.2.1. Getting NS-2

NS-2 is freely available from:

http://www.isi.edu/nsnam/dist/

7.2.2. Steps for Installation

a. Download the latest version of ns-allinone package

b. Copy this package into Cent OS

c. Extract package in root home

d. Go to folder ‟ns-allinone-2.33‟ and run “./install” in the terminal

[root@localhost ns-allinone-2.33]# ./install

e. After installation go back to root home and open bash profile in gedit

[root@localhost ~]# gedit .bash_profile

f. Copy the following paths in the bash profile (write the correct folder names)

# .bash_profile

# Get the aliases and functions

if [ -f ~/.bashrc ]; then

. ~/.bashrc

54

fi

# User specific environment and startup programs

PATH=$PATH:~/ns-allinone-2.33/bin:~/ns-allinone-

2.33/tcl8.4.18/unix:~/ns-allinone-2.33/tk8.4.18/unix

LD_LIBRARY_PATH=~/ns-allinone-2.33/otcl-1.13:~/ns-allinone-

2.33/lib

TCL_LIBRARY=~/ns-allinone-2.33/tcl8.4.18/library

export PATH

export LD_LIBRARY_PATH

export TCL_LIBRARY

unset USERNAME

g. Save and close gedit

h. Log out from root and then again log in

i. Now to validate the software go to /root/ns-allinone-2.33/ns-2.33 and run

“./validate”

[root@localhost ns-2.33]# ./validate

NS-2 is now ready to be used.

55

8. Appendix B

8.1. AWK Program Used

BEGIN {

sends=0;

recvs=0;

routing_packets=0.0;

droppedBytes=0;

droppedPackets=0;

highest_packet_id =0;

sum=0;

recvnum=0;

}

{

time = $2;

packet_id = $6;

# CALCULATE PACKET DELIVERY FRACTION

if (( $1 == "s") && ( $7 == "cbr" ) && ( $4=="AGT" )) { sends++; }

if (( $1 == "r") && ( $7 == "cbr" ) && ( $4=="AGT" )) { recvs++; }

# CALCULATE DELAY

if ( start_time[packet_id] == 0 ) {

start_time[packet_id] = time;

}

if (( $1 == "r") && ( $7 == "cbr" ) && ( $4=="AGT" ))

{ end_time[packet_id] = time; }

else { end_time[packet_id] = -1; }

# CALCULATE TOTAL OVERHEAD

if (($1 == "s" || $1 == "f") && $4 == "RTR" && $7 =="AODV")

routing_packets++;

# DROPPED PACKETS

if (( $1 == "D" ) && ( $7 == "cbr" ) && ( $2 > 0 ))

{

droppedBytes=droppedBytes+$8;

droppedPackets=droppedPackets+1;

}

#find the number of packets in the simulation

if (packet_id > highest_packet_id)

highest_packet_id = packet_id;

}

END {

for ( i in end_time )

{

start = start_time[i];

end = end_time[i];

56

packet_duration = end - start;

if ( packet_duration > 0 )

{ sum += packet_duration;

recvnum++;

}

}

delay=sum/recvnum;

NRL = routing_packets/recvs; #normalized routing load

PDF = (recvs/sends)*100; #packet delivery ratio[fraction]

printf("Sent packets = %.2f\n",sends);

printf("Received packets = %.2f\n",recvs);

printf("Dropped packets = %d\n",droppedPackets);

printf("Packet Delivery Fraction = %.2f\n",PDF);

printf("Normalized Routing Load = %.2f\n",NRL);

printf("E2E Delay in seconds = %.2f\n",delay);

printf("Routing Overhead = %.2f\n",routing_packets++);

printf("No. of dropped data (bytes) = %d\n",droppedBytes);

}

Documents

Simulation of Routing Protocols in Mobile Ad-Hoc Networks - Nusrah Kanwal