TABLE OF CONTENT

CHAPTER

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CONTENT PAGE

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Abstract

Table of Content

List of Figures

List of Tables

List of Abbreviation

1 INTRODUCTION 1

1.1 Mobile Ad-hoc Network (MANET) 1

1.1.1 Classification of Mobile Ad Hoc Network 1

1.1.2 What is Mobile Ad Hoc Network 2

1.2 Current Challenges 4

1.3 Objectives 5

1.4 Motivation 5

1.5 Routing Protocols Benefits 5

1.5.1 Table Driven (Proactive) Routing 5

1.5.2 On Demand (Reactive) Routing 7

1

1.5.3 Hybrid Routing 8

1.5.4 Hierarchical Routing Protocols 9

1.5.4.1 Application Used on Ad Hoc 10

1.5.4.2 Advantages and Disadvantages 10

1.5.4.3 Traditional Routing Protocols 11

1.6 Thesis Target 13

1.7 Thesis Outline 14

2 LITERARY SURVEY 15

2.1 Performance Analysis of Routing Protocols Based on

IPV4 and IPV6 for MANET

15

2.2 Performance comparison of OLSR, GRP and TORA using

OPNET

17

2.3. Performance Analysis of Multicast Routing Protocol for

Wireless Ad Hoc Network Based.

19

2.4 Ad Hoc Wireless Networks: Analysis, Protocols,

Architecture and Towards Convergence.

21

2.5 Simulation and Performance Analysis of AODV, TORA &

OLSR Routing Protocols Network

23

3 SYSTEM ANALYSIS 27

2

3.1 Challenge 28

3.2 Routing Dependability in Adhoc Networks 29

3.2.1 Node Misbehavior 30

3.2.2 Routing Dependability Problems 31

3.2.3 Systematic Performance Evaluation 31

3.3 Adhoc Wireless Routing Protocols 32

3.3.1 Classification of Basic Routing Protocols 32

3.4 Dynamic Source Routing Protocols (DSR) 33

3.4.1 Route Discovery phase 34

3.4.2 Route Maintenance 35

3.5 AODV Routing Protocol 36

3.5.1 Route Discovery phase 36

3.6 OLSR-INRIA 38

3.7 Hybrids - ZRP 40

3.8 Security Aware Routing Protocols 41

3.8.1 Security Goals 42

3.8.1.1 Attacks and Exploits on the Existing Protocols 43

4 SYSTEM ARCHITECTURE 44

4.1 Technical Approach 44

3

4.2 Technical Rationale 45

4.3 Structure Chart 47

4.3.1 Pure General Purpose Manet 47

4.3.2 Mesh Networks 48

4.4 Front End Design 50

4.5 Route Discovery 52

4.5.1 Characteristic Of Manet 53

4.5.2 A Split Design 57

5 EXPERIMENTAL SETUP 59

5.1 Simulation Tool 59

5.2 OPNET Architecture 59

5.3 Network Simulator 61

5.3.1 AODV 62

5.3.2 DSR 64

5.3.2.1 Flooding 64

5.4 OPNET Modeler Wireless Support 65

5.4.1 Implementing the Protocols in the OPNET Modeler 66

5.4.2 Implementing The Attack Model of the OPNET Modeler 68

5.4.3 Running Simulations in the OPNET Modeler 69

4

5.5 Scenario Setup 70

6 EXPERIMENTAL RESULTS 72

6.1 Result Analysis 72

6.2 Experiments in the begin environment 73

6.2.1 Throughput 80

6.2.2 End To End Delay Performance 81

6.3 Evaluation Result 85

6.3.1 Number of RREP Packets Sent By Node2 86

6.3.2 Transmitted Packets Average Delay 88

7 CONCLUSION AND FUTURE WORK 90

Conclusion 90

Future Work 92

Appendix A

Bibliographic 93

LIST OF FIGURES

5

FIGURE NO FIGURE NAME

1.1 Overview of Mobile Ad-hoc Network 3

1.2 OLSR- Overview 6

3.1 Adhoc Node 28

3.2 Routing System 30

3.3 Hierarchy of ad-hoc routing protocols 32

3.4 Route Discovery in DSR 35

3.5 Route Maintenance in DSR 36

3.6 Route discovery in AODV 37

3.7 Route OLSR 39

3.8 Zones a pro-active routing protocol is used while a re-

active protocol is used between zones.

40

3.9 The different components of the Zone Routing Protocol 41

3.10 Classification of attacks on MANET routing protocols 43

4.1 Internet System Architecture 45

4.2 4G Network Architecture 46

4.3 Structure Chart 47

4.4 Flow Chart of Routing Protocol 50

4.5 Route Request and Route Reply 52

4.6 Software Architecture of the AODV 56

6

4.7 Split Design 58

5.1 Simulation Cycle in OPNET 60

5.2 Steps to add new secure routing protocols into OPNET 66

5.3 Secure Conditions at the Intermediate Nodes 67

5.4 Procedure to integrate attack models in the routing

process

68

5.5 Experiments and collecting experimental data 69

6.1 Network scenario comprising of 52 mobile nodes and 7

different sources - Destination traffic pairs.

73

6.2 Clustering Creation and node distributed 74

6.3 Packet Delivery Fraction vs. pause time values in benign

environment

75

6.4 Normalized Routing load 76

6.5 Normalized Routing Load vs. pause time values in

benign environment

76

6.6 Throughput 79

6.7 Comparison of Jitter for OLSR-INRIA & SOLSR-

INRIA, DSR & SDSR and ZRP & SZRP for 52 & 72

79

6.8 Comparison of End-to-End Delay for OLSR-INRIA &

SOLSR-INRIA, DSR & SDSR and ZRP & SZRP for 52

& 72

83

6.9 Delay Vs Time 84

6.10 Delivery Ratio 85

7

6.11 Packet Delivery Ratio Vs Number of Connections 85

6.12 Number of RREP Sends By Node 2 Vs Number of

Connections

86

6.13 Number of RREP Sends By Node 2 Vs Number of

Connections Under Attacks

87

6.14 Average Delay Vs Number of Connections 88

6.15 Average Delay Vs Max Speed Of Node Movements 89

LIST OF ABBREVATIONS

3G - 3rd Generation Wireless Networks

8

AODV - Ad Hoc On Demand Distance Vector

AS - Autonomous System

BGP - Border Gateway Protocol

CBR - Constant Bit Rate

CGRS - Cluster head-Gateway Switching Routing

CIDR - Classless Inter Domain Routing

DHCP - Dynamic Host Configuration Protocol

DNS - Domain Name System

DSR - Dynamic Source Routing

DSDV - Destination Sequenced Distance Vector Routing

ERC - Equity Reciprocity and Competition Theory

FDVB - Fully Distributed Virtual Backbone

FSLS - Fuzzy Sighted Link State

GSM - Global System Mobile communications

HSLS - Hazy Sighted Link State

HSR - Hierarchical State Routing

IERP - Inter-Zone Routing Protocol

IETF - Internet Engineering Task Force

IP - Internet Protocol

ITU-T - International Telecommunication Union

9

IZRP - Intra-Zone Routing Protocol

LAR - Location Aided Routing

LCC - Least Cluster head Change

LSU - Link State Update

MAC - Medium Access Control

MANET - Mobile Ad hoc Networks

MPR - Multipoint Relay

OLSR - Optimised Link State Routing

OSPF - Open Shortest Path First

PAN - Personal Area Networks

PCM - Pulse Code Modulation

PDA - Personal Digital Assistant

POTS - Plain Old Telephony Service

QoS - Quality of Service

RREQ - Route Request

RREP - Route Reply

RTP - Real Time Protocol

SARP - Scalable Ad hoc Routing Protocol

TORA - Temporally Ordered Routing Algorithm

ToS - Type of Service

10

TKK - Teknillinen Korkeakoulu (Helsinki University of Technology)

TTL - Time To Live

UDP - User Datagram Protocol

VoIP - Voice over IP

WLAN - Wireless Local Area Networks

ZRP - Zone Routing Protocol

LIST OF TABLES

TABLE NO TABLE NAME

1.1 Protocol Advantages and Disadvantages 10

11

1.2 Traditional Routing Protocols 11

1.3 Routing Property 12

2.1 Analyzing Method 25

3.1 Summary Result for Test AODV, ERS 250 Nodes 29

3.2 Systematic Performance Evaluation 32

4.1 Hash Function 52

4.2 Surveying Different Techniques we Define the

Advantages and Disadvantages of Techniques

53

4.3 Comparison Between Manet-Protocols 55

5.1 Constants used in the AODV implementation 63

5.2 Constants used in the DSR 64

5.3 Hash Chain Function 67

5.4 Implementation matrix of routing attack models 69

5.5 Malicious node Assignment 71

6.1 The “baseline” metrics of the four protocols 78

6.2 Throughput 81

6.3 End to End Delay 82

CHAPTER 1

INTRODUCTION

1.1 MOBILE AD-HOC NETWORK (MANET):

12

A Mobile Ad-hoc Network (MANET) consists of a number of mobile battery

powered energy constraint nodes communicating with each other in single or multiple

hops over wireless links. They are temporary and infrastructure less without any central

controller. Every node generates its own data traffic and cooperatively forwards others

which are not in direct communication range of each other i.e. acts both as an end

terminal and router. Due to the mobility and dynamic addition/deletion of nodes,

topology changes frequently and on-demand routing protocols are required. MANETs

should be capable of handling these topology changes through network reconfigurations.

Routing protocols for MANET should be adaptive to the topology changes and be

capable of discovering new routes when old routes becomes invalid due to such change.

The number of nodes in MANET changes with time so the routing protocols should be

scalable.

A mobile ad hoc network is a collection of wireless mobile nodes that are

dynamically and arbitrarily located in such a manner that the interconnections between

nodes are capable of changing on a continual basis. There are some unique characteristics

of mobile ad hoc networks.

1.1.1 CLASSIFICATION OF MOBILE AD HOC NETWORK

Current researches classify mobile ad hoc networks into two categories. The first

one is called a managed environment, where a common, trusted authority exists to

provide certain services, such as a certificate authority. Another is called open

environment, where a common authority that regulates the network does not exist.

It is also referred as full self-organization environment, namely the network has

the ability to work without any external management and configuration. Extensive work

has been done recently in both areas.

The routing protocols can be roughly divided into three categories: proactive

(table driven routing protocols), reactive (on-demand routing protocols), and hybrid. The

primary goal of such an ad hoc network routing protocol is to provide correct and

13

efficient route establishment between pair of nodes so that messages may be delivered in

time. Cluster Based Routing Protocol (CBRP) is a routing protocol designed for use in

mobile ad hoc networks. The protocol divides the nodes into a number of overlapping or

disjoint clusters in a distributed manner. A cluster head is elected for each cluster to

maintain cluster membership information. Inter-cluster routes are discovered dynamically

using the cluster membership information kept at each cluster head. By clustering nodes

into groups, the protocol efficiently minimizes the flooding traffic during route discovery

and speeds up this process as well.

1.1.2 WHAT IS MOBILE AD HOC NETWORK?

Mobile Ad-hoc network is a set of wireless devices called wireless nodes, which

dynamically connect and transfer information. Wireless nodes can be personal computers

(desktops/laptops) with wireless LAN cards, Personal Digital Assistants (PDA), or other

types of wireless or mobile communication devices. Figure 1.1 illustrates what MANET

is. In general, a wireless node can be any computing equipment that employs the air as

the transmission medium. As shown, the wireless node may be physically attached to a

person, a vehicle, or an airplane, to enable wireless communication among them.

FIG 1.1 OVERVIEW OF MOBILE AD-HOC NETWORK

14

In MANET, a wireless node can be the source, the destination, or an intermediate

node of data transmission. When a wireless node plays the role of intermediate node, it

serves as a router that can receive and forward data packets to its neighbor closer to the

destination node. Due to the nature of an ad-hoc network, wireless nodes tend to keep

moving rather than stay still. Therefore the network topology changes from time to time.

Wireless ad-hoc network have many advantages:

Low cost of deployment: Ad hoc networks can be deployed on the fly; hence no

expensive infrastructure such as copper wires or data cables is required.

Fast deployment: Ad hoc networks are very convenient and easy to deploy since

there are no cables involved. Deployment time is shortened.

Dynamic Configuration: Ad hoc network configuration can change dynamically

over time. When compared to configurability of LANs, it is very easy to change

the network topology of a wireless network.

MANET has various potential applications. Some typical examples include

emergency search-rescue operations, meeting events, conferences, and battlefield

communication between moving vehicles and/or soldiers. With the abilities to meet the

new demand of mobile computation, the MANET has a very bright future.

1.2 CURRENT CHALLENGES

In a mobile ad hoc network, all the nodes cooperate with each other to forward the

packets in the network, and hence each node is effectively a router. Thus one of the most

important issues is routing. This thesis focuses mainly on routing issues in ad hoc

networks. In this section, some of the other issues in ad hoc networks are described:

Distributed network: A MANET is a distributed wireless network without

any fixed infrastructure. That means no centralized server is required to

maintain the state of the clients.

Dynamic topology: The nodes are mobile and hence the network is self-

organizing. Because of this, the topology of the network keeps changing

15

over time. Consequently, the routing protocols designed for such networks

must also be adaptive to the topology changes.

Addressing scheme: The network topology keeps changing dynamically

and hence the addressing scheme used is quite significant. A dynamic

network topology requires a ubiquitous addressing scheme, which avoids

any duplicate addresses. In wireless WAN environments, Mobile IP is

being used. Because the static home agents and foreign agents are needed,

hence, this solution is not suitable for ad hoc network.

Security: Security in an ad hoc network is extremely important in

scenarios such as a battlefield. The five goals of security – availability,

confidentiality, integrity authenticity and non-repudiation - are difficult to

achieve in MANET, mainly because every node in the network

participates equally in routing packets. Security issues in MANETs are

discussed in Chapter III.

1.3 OBJECTIVE:

To study various cluster based routing schemes in mobile ad-hoc networks and

schemes in mobile ad-hoc networks and implement distributed weighted cluster based

implement distributed weighted cluster based routing algorithm.

Design a routing protocol for MANET that is Efficient, scalable, distributed and simple

to implement. Evaluate CBRP through simulation compare with different design

alternatives compare against other MANET protocols.

1.4 MOTIVATION:

16

Major design decision use clustering approach to minimize on-demand route

discovery traffic, use “local repair” to reduce route acquisition delay and new route

discovery traffic suggest a solution to use uni-directional links

A lot of research is currently going on in moiled-hoc networks. Chief occurs being to

develop an efficient routing protocol which provides for efficient communication with

minimum energy requirement.

1.5. ROUTING PROTOCOLS BENEFITS

1.5.1 TABLE-DRIVEN (PROACTIVE) ROUTING

This type of protocols maintains fresh lists of destinations and their routes by periodically

distributing routing tables throughout the network. The main disadvantages of such

algorithms are:

Respective amount of data for maintenance.

Slow reaction on restructuring and failures.

FIG 1.2: OLSR-OVERVIEW

17

EXAMPLES OF PROACTIVE ALGORITHMS ARE:

Optimized Link State Routing Protocol (OLSR) Optimized Link State Routing Protocol RFC 3626.

Babel RFC 6126

Destination Sequence Distance Vector (DSDV)

BENEFITES

Being a proactive protocol, routes to all destinations within the network are

known and maintained before use. Having the routes available within the standard

routing table can be useful for some systems and network applications as there is

no route discovery delay associated with finding a new route.

The routing overhead generated, while generally greater than that of a reactive

protocol, does not increase with the number of routes being created.

Default and network routes can be injected into the system by HNA messages

allowing for connection to the internet or other networks within the

OLSR MANET cloud. Network routes are something reactive protocols do not

currently execute well.

Timeout values and validity information is contained within the messages

conveying information allowing for differing timer values to be used at differing

nodes.

1.5.2 ON-DEMAND (REACTIVE) ROUTING

This type of protocols finds a route on demand by flooding the network with Route

Request packets. The main disadvantages of such algorithms are:

High latency time in route finding.

Excessive flooding can lead to network clogging.

18

Examples of on-demand algorithms are:

Ad hoc On-demand Distance Vector (AODV) (RFC 3561}

Dynamic Source Routing (RFC 4728)

Flow State in the Dynamic Source Routing

Power-Aware DSR-based

BENEFITS

The main advantage of this protocol is having routes established on demand and

that destination sequence numbers are applied to find the latest route to the

destination. The connection setup delay is lower.

One disadvantage of this protocol is that intermediate nodes can lead to

inconsistent routes if the source sequence number is very old and the intermediate

nodes have a higher but not the latest destination sequence number, thereby

having stale entries.

Also, multiple RouteReply packets in response to a single RouteRequest packet

can lead to heavy control overhead. Another disadvantage of AODV is

unnecessary bandwidth consumption due to periodic beaconing.

1.5.3 HYBRID (BOTH PROACTIVE AND REACTIVE) ROUTING

This type of protocol combines the advantages of proactive and reactive routing. The

routing is initially established with some proactively prospected routes and then

serves the demand from additionally activated nodes through reactive flooding. The

choice of one or the other method requires predetermination for typical cases. The

main disadvantages of such algorithms are:

Advantage depends on number of other nodes activated.

Reaction to traffic demand depends on gradient of traffic volume.

19

EXAMPLES OF HYBRID ALGORITHMS ARE:

ZRP (Zone Routing Protocol) ZRP uses IARP as pro-active and IERP as reactive

component.

BENEFITS:

What is called the Intra-zone Routing Protocol (IARP), or a proactive routing

protocol, is used inside routing zones. What is called the Inter-zone Routing

Protocol (IERP), or a reactive routing protocol, is used between routing zones.

IARP uses a routing table. Since this table is already stored, this is considered a

proactive protocol. IERP uses a reactive protocol.

Any route to a destination that is within the same local zone is quickly established

from the sources proactively cached routing table by IARP. Therefore, if the

source and destination of a packet are in the same zone, the packet can be

delivered immediately.

Most existing proactive routing algorithms can be used as the IARP for ZRP.

In ZRP a zone is defined around each node, called the node's k-neighborhood,

which consists of all nodes within k hops of the node. Border nodes are nodes

which are exactly k hops away from a source node.

For routes beyond the local zone, route discovery happens reactively. The source

node sends a route request to the border nodes of its zone, containing its own

address, the destination address and a unique sequence number. Each border node

checks its local zone for the destination. If the destination is not a member of this

local zone, the border node adds its own address to the route request packet and

forwards the packet to its own border nodes. If the destination is a member of the

local zone, it sends a route reply on the reverse path back to the source. The

source node uses the path saved in the route reply packet to send data packets to

the destination

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1.5.4 HIERARCHICAL ROUTING PROTOCOLS

With this type of protocol the choice of proactive and of reactive routing depends on the

hierarchic level in which a node resides. The routing is initially established with some

proactively prospected routes and then serves the demand from additionally activated

nodes through reactive flooding on the lower levels. The choice for one or the other

method requires proper attributation for respective levels. The main disadvantages of

such algorithms are:

Advantage depends on depth of nesting and addressing scheme.

Reaction to traffic demand depends on meshing parameters.

EXAMPLES OF HIERARCHICAL ROUTING ALGORITHMS ARE:

CBRP (Cluster Based Routing Protocol)

FSR (Fisheye State Routing protocol)

1.5.4.1 APPLICATION USED ON ADHOC:

To understand their application we have to see what they offer and how they

establish

Establishing this type of networks requires mobile devices with the right

communicating chip on.

While they could ideally be deployed at any where or in other words

instantaneous deployment.

The cooperation of the users is necessary to the operation of ad-hoc networks;

therefore, game theory provides a good basis to analyze the networks.

Work has been going on to introduce the fundamental concepts of game theory

and its applications in telecommunications.

Crisis management services applications

21

1.5.4.2 ADVANTAGES AND DISADVANTAGES

Table 1.1: Protocol Advanages and Disadvantages

PROTOCOL ADVANTAGES DISADVANTAGES

Proactive Upto date routing information Quick establishments of routes Small Delay A route to every other node in

the network is always.

Slow convergence Tendency of creating

loops Large amount of

resource are needed. Routing information in

not dully used.Reactive Reduction of routing load

Saving resources Loops-free

Not always up to date routes

Large delay Control traffic and

overhead costHybrid Scalability

Limited search cost Up-to date routing information

within zones

Arbitrary proactive schemes within zones.

Inter zone routing latencies.

More resource for large size zones.

The study has been done to compare the efficiency of the various categories of

routing protocols: DSDV, AODV, FSR, LAR, OLSR, STAR, and ZRP. The overall goal

of our simulation study is to analyze the behavior and performance of the protocols under

a range of various scenarios. Simulations have been run using a mobile ad hoc networks

composed of 10, 15, 25, 50 and 75 nodes moving over a rectangular 1500 m × 1500 m

space and operating over 30 seconds of simulation time. All nodes move according to the

random way point mobility model.

Table 1.2: Traditional Routing Protocols

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1.5.4.3 TRADITIONAL ROUTING PROTOCOLS:

Border Gateway Protocol (BGP) is the protocol backing the core routing

decisions on the Internet. It maintains a table of IP networks or ‘prefixes’ which

designate network reach-ability among autonomous systems (AS). It is described

as a path vector protocol. BGP does not use traditional Interior Gateway

Protocol(IGP) metrics, but makes routing decisions based on path, network

policies and/or rule-sets. For this reason, it is more appropriately termed a reach-

ability protocol rather than routing protocol.

Open Shortest Path First (OSPF) is an adaptive routing protocol for Internet

Protocol (IP) networks. It uses a link state routing algorithm and falls into the

group of interior routing protocols, operating within a single autonomous

system (AS).

Table 1.3: Routing Property

Routing property Proactive Reactive Hybrid

Routing structure Both flat and hierarchical

Mostly flat, except CBRP

Mostly hierarchical

Route availability Always available, if the nodes reachable

Determined when needed

Depends on the location of the destination

23

Traffic control Usually high Low Mostly lower than proactive and reactive

Mobility handling effects

usually updates occurs based on mobility at fixed intervals

ABR introduced LBQ, AODV uses local route discovery

Usually more than one path may be available

Storage requirements

High Usually lower than proactive protocols

Usually depends on the size of each cluster

Delay level Some all routes are predetermined

Higher than proactive

For local destination small, since inter zone may be as large as reactive protocols.

Scalability level to perform efficient routing

Usually up to 100 nodes

Source routing protocols up to few 100 nodes point to point may scale higher

Designed for up to 1000 or more nodes

1.6 THESIS TARGET

The mobile ad hoc network is a new model of wireless communication and has

gained increasing attention from industry. As in a general networking environment,

mobile ad-hoc networks have to deal with various security threats. Due to its nature of

dynamic network topology, routing in mobile ad-hoc network plays a vital role for the

performance of the networks. It is understandable that most security threats target routing

protocols – the weakest point of the mobile ad-hoc network. There are various studies

and many researches in this field in an attempt to propose more secure protocols.

However, there is not a complete routing protocol that can secure the operation of an

entire network in every situation. Typically a “secure” protocol is only good at protecting

the network against one specific type of attacks.

24

Many researchers have been done to evaluate the performance of secure routing

protocols in comparison with normal routing protocols. One of the objectives of this

research is to examine the additional cost of adding a security feature into non-secure

routing protocols in various scenarios. The additional cost includes delay in packet

transmission, the low rate of data packets over the total packets sent, etc.

It is well known that the real-world network does not operate in an ideal working

environment, meaning that there are always threats and malicious actions affecting the

performance of the network.

Thus, studying the performance of secure routing protocols in malicious

environments is needed in order to effectively evaluate the performance of those routing

protocols. In the thesis, I have implemented two secure routing protocols: a secure

version of the dynamic source routing - DSR (OLSR) and Secure Ad hoc On-demand

Distance Vector routing protocol (SAODV) in the OPNET simulation environments. I

will also create malicious scenarios by implementing several attacks in the simulation

environments.

In ad hoc networks, nodes are not familiar with the topology of their networks.

Instead, they have to discover it: typically, a new node announces its presence and listens

for announcements broadcast by its neighbors. Each node learns about others nearby and

how to reach them, and may announce that it too can reach them.

1.7 THESIS OUTLINE

This thesis is composed of six chapters. Following the Introduction Chapter (I),

Chapter II classifies the routing protocols. The working description of two reactive

protocols is provided. The chapter is concluded with a summary.

Chapter III discusses security issues in MANETs with a focus on secure routing

in MANETs. It focuses on the attacks and exploits that are possible in an ad hoc wireless

network. It explains the working mechanism of four of the state-of-the-art routing

25

protocols including OLSR and Secure Ad hoc On-demand Distance Vector routing

protocols.

Chapter IV discusses the system Architecture employed to study the performance

of routing protocols in MANETs. A brief description of the OPNET Modeler simulator

environment is provided. The scenarios, metrics and the issues faced are explained. A

summary concludes the chapter.

Chapter V discusses the simulation approach employed to study the performance

of routing protocols in MANETs. A brief description of the OPNET Modeler simulator

environment is provided. The scenarios, metrics and the issues faced are explained. A

summary concludes the chapter.

Chapter VI forms the core of this thesis and discusses the experiments carried out

to analyze the performance of DSR, OLSR-INRIA, AODV, ZRP and SAODV. The

experimental results and their analyses follow the experiments.

Chapter VII concludes this thesis along with suggestions for future work in the

area of mobile ad hoc networks.

CHAPTER 2

LITERATURE SURVEY

2.1 PERFORMANCE ANALYSIS OF ROUTING PROTOCOLS

BASED ON IPV4 AND IPV6 FOR MANET

Ad hoc network is a collection of wireless mobile nodes where wireless radio

interface connects each device in a MANET to move freely, independently and randomly.

Routing protocols in mobile ad hoc network helps to communicate source node with

destination node by sending and receiving packets. Many authors have compared various

routing protocols such as AODV, DSR, DSDV, TORA, DYMO, OLSR etc in the past. In

this paper, we have analyzed the behavior of three routing protocols AODV (Ad hoc on

26

demand distance vector), DYMO Dynamic MANET On demand), and OLSR (Optimized

link state routing) in the network protocol IPV4 & IPV6 and compared the performance

of these protocols using Qualnet5.0.2 simulator. The performance metrics are

Throughput, Average Jitter, Packet Delivery Ratio & Total Packets Received. To test

competence and effectiveness of all three protocols under IPV4 & IPV6, Changing the

speed and mobility. Finally results are scrutinized from different scenarios to provide

qualitative assessment of the applicability of the protocols.

A mobile ad hoc network (MANET) is a self- configuring network of mobile

devices connected by wireless links. In other words, a MANET is a collection of

communication nodes that wish to communicate with each other, but has no fixed

infrastructure and no predetermined topology of wireless links. Each node in a MANET

is free to move independently in any direction, and will therefore change its links to other

devices frequently. Individual nodes are responsible for dynamically discovering other

nodes that they can directly communicate with. Due to the limitation of signal

transmission range in each node, not all nodes can directly communicate with each other.

Each node must forward traffic unrelated to its own use, and therefore be a router. The

primary challenge in building a MANET is equipping each device to continuously

maintain the information required to properly route traffic. Therefore, nodes are required

to relay packets on behalf of other nodes in order to deliver data across the network.

Ad hoc networks can be built around any wireless technology, including infrared,

radio frequency (RF), global positioning system (GPS), and so on. Usually, each node is

equipped with a transmitter and a receiver to communicate with other nodes. Military

application, Collaborative & Distributed Computing, Emergency Operation, Wireless

Mesh Network and the routing protocol should be able to provide quick, secure and

reliable multicast communication with support for real time traffic. The paper is

distributed as follows. In section 2 we have discuss three routing protocols taken for

comparison. Section 3 gives the details of simulation environment. The simulation results

are shown in section 4. Sections 5 describe conclusion and future scope.

27

SIMULATION RESULTS, WE CONCLUDE THAT FOR IPV4 AND IPV6:

DYMO have better throughput than AODV and OLSR with IPV4.

DYMO have better throughput than AODV and OLSR with IPV6.

OLSR have low jitter and average end to end delay corresponds to high efficiency

than DYMO and AODV with IPV4.

OLSR have low jitter and average end to end delay corresponds to high efficiency

than DYMO and AODV with IPV6.

OLSR have better packet delivery ratio than DYMO and AODV with IPV4.

OLSR have better packet delivery ratio than DYMO and AODV with IPV6.

OLSR have better average packed received and broadcast packet received than

AODV and DYMO with IPV4.

OLSR have better average packed received and broadcast packet received than

DYMO and AODV with IPV6.

We also conclude that IPV6 performs better than IPV4.

2.2. PERFORMANCE COMPARISON OF OLSR, GRP AND TORA

USING OPNET

A MANET is an autonomous collection of mobile users that communicate over

relatively bandwidth constrained wireless links. Since the nodes are mobile, the network

topology may change rapidly 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 incorporated

into mobile nodes.. In this paper routing protocols OLSR, GRP and TORA for mobile ad

hoc network are compared on the basis of delay, load, media access delay and

throughput.

28

MANET is a dynamic distributed network [1], in which mobile devices with

limited energy can move arbitrary. MANET is a self-configurable network without

infrastructure in which nodes are free to move randomly, so topology may change and

this event is unpredictable [6]. Because of these characteristics, routing is a critical issue

and an efficient routing protocol needs to be chosen to make the MANET reliable [2].

The most popular routing protocols [3] in MANET are OLSR (proactive) and

TORA(reactive) and GRP(hybrid) .Proactive protocols are table driven protocols and find

routes before they need it. Reactive protocols find the routes when they are needed And

finally hybrid routing protocols offer an efficient framework that can simultaneously

draw on the strengths of proactive and reactive routing protocols. In this paper, three

MANET routing protocols ,OLSR, TORA and GRP are evaluated on the basis of four

parameters : delay, load, throughput and routing overhead.

ROUTING PROTOCOL:

The performance investigation of reactive and proactive MANET routing

protocols, namely AODV, DSR, TORA and OLSR is done by Ashish Shrestha and Firat

Tekiner. They have concluded that with regards to overall performance, AODV and

OLSR performed pretty well. However,

AODV showed better efficiency to deal with high congestion and it scaled better

by successfully delivering packets over heavily trafficked network compared to OLSR

and TORA. Comparison of OLSR and TORA has been done by Pankaj Palta and Sonia

Goyal in.They have concluded that OLSR is better in those scenario where bandwidth is

large as OLSR always updated their nodes so large bandwidth is used than TORA on

same conditions. Simulation and analysis of GRP routing protocol has been done by

kuldeep vats, Mandeep Dalal , Deepak Rohila and Vikas Laura.Simulation results show

29

that GRP protocol has better performance in terms of delay , total traffic sent and

received routing traffic sent and received in packet and bit form ,packet copy, packet

created and packet destroyed. Manijeh Keshtgary and Vahide Babaiyan, used OPNET

14.5 for simulation. The simulation study for MANET network under routing protocols

AODV, DSR, OLSR, and GRP were deployed using FTP traffic analyzing. These

protocols were tested with QOS parameters. From their analysis, the OLSR outperforms

others in overall performance and GRP has least media access delay and delay. This

result is verified by Kuldeep Vats, Monica Sachdeva and Dr .Krishan Saluja in. They

also concluded that OLSR is best in overall performance followed by GRP.

In this paper, performance of three routing protocols namely OLSR, GRP and

TORA was analyzed .OLSR performs best in terms of load and throughput.GRP

performs best in terms of delay and routing overhead.

2.3. PERFORMANCE ANALYSIS OF MULTICAST ROUTING

PROTOCOL FOR WIRELESS AD HOC NETWORK BASED ON

TRAFFIC PATTERN WITH VARYING NODE MOBILITY

Data and information transmission in a wireless mobile ad-hoc networks

(MANET) mainly relies on the performance of the traffic pattern (application traffic

agent and data traffic) used in a network. The reliability and capability of routing

protocols can be determined using different traffic scenarios, which insist its performance

analysis using traffic patterns TCP/FTP and UDP/CBR with routing protocol generally

implemented in a mobile ad-hoc environment. This paper describes the performance

analysis and comparison of CBR and TCP traffic over conventional AODV and multicast

AODV. The performance metrics, such as throughput, packet delivery ratio and average

30

end to end delay is used for comprehensive performance analysis. The average end to end

delay of CBR/UDP for MAODV and AODV is lesser than TCP/FTP. The Average

End2End Delay of MAODV is lesser than that of AODV for both traffics. The results

follow these trends over a wide range of simulations based on node mobility.

The mobile ad-hoc network is a self-configuring infrastructure less network

without the need of any central administration. Therefore, they are well suited for the

environments as earthquake prone areas, military battlefield operation, virtual

classrooms, and many other emergency services. AODV is a protocol which is capable of

unicast and multicast transmission. Multicasting in a wireless network is a diverse

technique through which the message can be transferred to multiple nodes simultaneously

using fewer links. The information is delivered to each of the links only once, and copies

are created when the link to the destination splits, thus creating an optimal distribution

path.

In general, for multicast transmissions there are two types of nodes, source node

and multicast member node. The source node primarily spreads out a multicast data to

multiple multicast member nodes that want to receive that data and join the multicast

group.

A big challenge in the design of ad hoc networks is the development of dynamic

routing protocols that can find routes, transfer information and data efficiently between

two nodes. Each node in the network also acts as a router, forwarding data packets for

other nodes.

The study of performance of two protocols, unicast AODV and multicast

MAODV has been analysed over different scenarios. The analysis has been carried out

with two traffic types, TCP/FTP and CBR/UDP. From the analysis it is concluded that

MAODV performs slightly better than AODV in terms of Packet Delivery Ratio,

End2End delay with varying node speed over two traffics, TCP and CBR. From

experimental analysis it is concluded that in low density and in low speed the Packet

Delivery Ratio (PDR) is high for both TCP and CBR. In the same scenario the End2End

31

Delay for CBR traffic is lower than TCP traffic for both protocols. With mobility model

it is also concluded that MAODV performs better than AODV for both TCP and CBR

traffic patterns. In future the analysis may be extended to analyze the performance with

node density, packet generation rate, varying pause time etc. By evaluating the

performance of these two protocols over different scenarios, it will help in designing a

new protocol or improvement in the existing protocol.

2.4. AD HOC WIRELESS NETWORKS: ANALYSIS, PROTOCOLS,

ARCHITECTURE AND TOWARDS CONVERGENCE

Traditional routing protocols were developed to support user communication in

networks with a fixed infrastructure with reliable, high-capacity links. On the other hand

Mobile Ad-hoc Network is a collection of wireless mobile nodes which dynamically

forms a temporary network without the use of any existing network infrastructure or

centralized administration. These networks need efficient routing protocols; various ad

hoc routing protocols have been proposed and compared based on some metrics. We

present the analytical simulation results of routing protocols DSR, AODV, OLSR and

GRP for two applications namely ftp and email, using the network simulator OPNET

14.0.

32

Traditional routing protocols were developed to support user communication in

networks with a fixed infrastructure with reliable, high-capacity links. However, in the

mobile ad hoc network, the network infrastructure is dynamically changing, and the links

are wireless with less capacity and more prone to errors. These nodes generally have a

limited transmission range and, so, each node seeks the assistance of its neighboring

nodes in forwarding packets and hence the nodes in an ad-hoc network can act as both

routers and hosts, thus a node may forward packets between other nodes as well as run

user applications. Some examples of the possible uses of ad hoc networking include

students using laptop computers to participate in an interactive lecture, business

associates sharing information during a meeting, soldiers relaying information for

situational awareness on the battlefield and emergency disaster relief personnel

coordinating efforts after a hurricane or earthquake.

It is evident from Table 6 that the performance of DSR for all parameters is worst

as compared to the other protocols. On the other hand OLSR is performing well for all

parameters. The performance of GRP is also very close to OLSR but not better than it.

As far as the present results are concerned in the given scenario the protocols are

ordered in the increasing order of their performance as DSR, AODV, GRP and OLSR.

GEOGRAPHIC ROUTING PROTOCOL (GRP)

GRP is a kind of position-based protocol which belongs to Proactive Routing

Protocol. Each position of the node will be marked by GPS and flooding will be

optimized by quadrants. Flooding position updates on distance the node moved and

neighborhood crossings. A hello protocol will be exchanged between nodes to identify

their neighbors and their positions. At the same time, by means of route locking a node

can return its packet to the last node when it can’t keep on sending the packet to the next

node.

AD-HOC ON DEMAND DISTANCE VECTOR (AODV)

33

AODV discovers routes on an as needed basis via a similar route discovery

process. However, AODV adopts a very different mechanism to maintain routing

information. It uses traditional routing tables, one entry per destination. Without source

routing, AODV relies on routing table entries to propagate an RREP back to the source

and, subsequently, to route data packets to the destination. AODV uses sequence

numbers maintained at each destination to determine freshness of routing information and

to prevent routing loops. All routing packets carry these sequence numbers. An important

feature of AODV is the maintenance of timer-based states in each node, regarding

utilization of individual routing table entries. A routing table entry is expired if not used

recently.

2.5. SIMULATION AND PERFORMANCE ANALYSIS OF AODV, TORA &

OLSR ROUTING PROTOCOLS

An ad hoc network is a collection of wireless mobile nodes dynamically forming

a temporary network without the use of any pre-existing network infrastructure. A

number of ad hoc routing protocols have been developed during the time, but none of

these is able to produce efficient routing of packets in large number of nodes due to their

own limitations. Therefore, scalability is an open issue in all routing protocols.

In this paper, we presented our observations regarding the scalability comparison

of the three MANET routing protocols, Ad hoc On Demand Distance Vector (AODV),

Temporally Ordered Routing Protocols (TORA) and Optimized Link State Routing

(OLSR) by varying the number of nodes.

34

In last three decades, wireless network has grown enormously. Although, wireless

network has eased the information sharing and communication but we have to setup static

links before we can start the communication between two systems. This form of network

is known as infrastructure network. These networks can only work in the environment

where a fixed infrastructure exists. This motivates the need of infrastructure less

networks which are known as ad hoc networks. Ad-hoc means “for one specific purpose

only”. Hence, these networks are formed when needed. All available nodes are aware of

all other nodes within range. The entire collection of nodes is interconnected in many

different ways. The topology of such networks changes very rapidly because the nodes in

ad hoc network are mobile and independent of each other. This makes the routing very

difficult.

In this research study, we have performed simulations of three MANET routing

protocols AODV, TORA and OLSR to evaluate their scalability and then compared them.

Simulation is done using the OPNET Modeler 14.5. In the research work, Average end to

end delay and throughput are considered as the performance evaluation parameters.

HTTP heavy browsing is used for traffic generation. The simulation results conclude that

on increasing the number of nodes there is performance degradation in all protocols, but

it varies from protocol to protocol. As the number of nodes increased the network

average end to end delay also increased for all three routing protocols. However, OLSR

protocol outperformed the AODV and TORA protocols and has least network latency.

TORA performed worst even it uses the localization.

In case of network throughput too, it is observed that on varying the number of

nodes performance of TORA protocol was very poor. Whereas, the performance of the

OLSR protocol was far better than the AODV and TORA in terms of throughput. AODV

performance was average during the simulation however; it reduces the routing overhead

to great extent and reacts quickly during its operation. Hence, this paper concludes that

the OLSR protocol in highly scalable with reference to varying network size, however the

AODV protocol is almost equally scalable but less than OLSR. This comparative analysis

35

is done to identify the suitable protocols according to the network size, so that the routing

could be more efficient and cost effective.

TABLE 2.1: ANALYZING METHOD

Author Name

References

Protocols

Used

Simulator Performance

Metrics

Variable

Parameters

Guntupalli et

al.

DSDV, DSR,

AODV

NS2 Average End to

End Delay,

Normalized

Routing Load,

Packet Delivery

Ratio

Number of

nodes, Speed,

pause time,

Transmission

Power.

Yogesh et al. AODV, DSR GLOMOSIM Packet Delivery

Ratio, End to

End Delay,

Normalized

Number of

nodes, Speed,

pause time

36

routing

overhead.

Chenna et al, DSDV,

AODV, DSR,

TORA

NS2 Throughput,

Routing

Overhead, Path

Optimality,

Packet Loss,

Average DeLay

Traffic Loads,

Movement

Patterns.

G. Jayakumar

et al,

AODV, DSR NS2 Packet Delivery

Ratio, Routing

Overhead,

MAC load and

average End to

End Delay

Speed

Birdar et al, AODV, DSR Packet Delivery

Ratio, Routing

Overhead,

Normalized

Routing

Overhead and

Average End to

End Delay

Pause Time

Vijayalaskhmi

et al,

DSDV,

AODV

NS2 Packet Delivery

Ratio, Average

End to End

Delay and

Throughput.

Number of

Nodes, Speed,

Time

Shaily et al, AODV, ZRP Qual Net Packet Delivery

Traction,

Average End to

Pause Time

37

End Delay and

Throughput.

Li Layuan st

al,

DSDV,

AODV, DSR,

TORA

NS2 Average Delay,

Jitter, Routing

Load, Loss

Ratio,

Throughput and

Connectivity

Network Size.

CHAPTER 3

SYSTEM ANALYSIS

In MANET the wireless links between adjacent nodes are subject to interference

from external sources, intra and inter transmission in the network, ambient noise in the

system and jamming signals from malicious nodes. The cumulative effect of all these

factors results in low link capacity and reliability. In literature Kumar et al modifies the

MANET routing protocols to reduce network congestion without taking into account the

reliability of wireless links. It resulted in an only traffic load aware routing to reduce

congestion. On the other hand Vijayavani et al modifies and compares various routing

protocols in MANET based on network size, density and node mobility. Here also the

wireless link status is not considered. Ghosh et al considered the status of wireless links

in DSR and achieved good results.

38

In our work we have modified the route discovery process of OLSR-INRIA, DSR

and ZRP to select the most reliable path amongst multiple available paths based on its

SNR value. The reliability of a path is the minimum SNR value of the wireless links

constituting the path as it defines the weakest portion of the path. The structure of the

RREQ packet is modified to include an additional field known as ROUTE_MIN_SNR, to

store the minimum SNR value among all the path links. It gives us a measure of the path

reliability. During the initial stages of the route discovery process the source node

broadcasts RREQ packets to its immediate neighborhood. The ROUTE_MIN_SNR field

of the RREQ packets received by the neighborhood nodes is updated with the SNR value

of the link from the physical layer. After this updating the RREQ packets are further

broadcasted in the immediate neighborhood. This process continues until the RREQ

packets reaches destination node

. When the destination node receives the RREQ packets, it compares the SNR

value of each path to the source which is above a certain threshold (10dB in our method).

Among the possible paths one with the maximum SNR value is selected as it gives the

maximum throughput, reliability with minimum delay.

39

HOW TO ANALYZE (MOBILE AD HOC) NETWORKS?

FIG 3.1: ADHOC NODE

3.1 CHALLENGE:

Qualify and quantify the effects of Node misbehavior on the overall performance

of the routing system.

We would like to see how the system behaves.

What about choice of evaluation technique?

Real world observations are not possible because there is no large scale manet,

and it would be expensive to set up a new one.

Emulation / Tested experiments are possible but in a small scale.

Simulation studies are being conducted.

Security, 

QoS, 

40

TABLE 3.1: SUMMARY RESULT FOR TEST AODV, ERS, 250 NODES

It is for sure that there are many issues need to be handled if an optimized ad hoc network

needs to be implemented which does not seem possible with today's technology.

3.2 ROUTING DEPENDABILITY IN AD HOC NETWORKS

The effects of node misbehavior.

Modeling adhoc networks.

 There might be cases that the protocols that we have discussed cannot help out. For

instance what if there are some nodes that do not want to cooperate? Or some other

problems related proximity to each other. Some might behave as malicious and etc.

Recall that in ad hoc networks, there is mobility, dynamic situations. In this part, our

concern is Routing system.  

41

FIG 3.2: ROUTING SYSTEM

3.2.1 NODE MISBEHAVIOR

A node in the middle may keep the message and not forward to package. It can

affect the overall performance of the system. There are three different nodes.

1. Well-behaving nodes: that works, forwards the packet.

2. Malicious nodes:  the ones that inject false information into messages or remove them

completely from the network (black holes).

It has been proven that if the number of selfish nodes increases the packet loss in the

network increases linearly as well.

Besides that, in case of AODV, if there are many selfish nodes in the network we need to

incerase the number of control messages ( to keep the track of what is going on in the

network , and reestablish route if a node does not forward the packet ) . It results in

increase of routing overhead.   Selfish nodes:  the ones that receives the packet but do not

forward it. 

42

3.2.2 ROUTING DEPENDABILITY PROBLEMS

Most ad hoc routing algorithms assume only well-behaving nodes to support

multi-hop operation of the network. However if something goes wrong in between,

everything can be affected in a negative way.

UNDERLYING PROBLEMS

Induced by mobility : High topology dynamics

Induced by wireless communication

Induced by node misbehavior ( we might want to add some extra mechanisms to

overcome this)

3.2.3 SYSTEMATIC PERFORMANCE EVALUATION

Performance analysis = analysis + computer systems

System = any collection of hardware + software

Metrics = the criteria used to evaluate the system performance

Workloads = the requests made by the users of the system

You need to know what you want to characterize in your system. You need to have a

proper goal first. There is no such thing as general model.

Goals -> correct metrics, workloads, methodology.

Your performance evaluation should represent the actual usage of the system.

43

TABLE 3.2: SYSTEMATIC PERFORMANCE EVALUATION

3.3 AD HOC WIRELESS ROUTING PROTOCOLS

3.3.1 CLASSIFICATION OF BASIC ROUTING PROTOCOLS

Routing protocols in ad hoc mobile wireless network can generally be divided

into three groups (Figure 3.2):

44

FIG 3.3 HIERARCHY OF AD-HOC ROUTING PROTOCOLS

Table driven: Every node in the network maintains complete routing information

about the network by periodically updating the routing table. Thus, when a node

needs to send data packets, there is no delay for discovering the route throughout the

network. This kind of routing protocols roughly works the same way as that of

routing protocols for wired networks.

Source initiated (or demand driven): In this type of routing, a node simply maintains

routes to active destination that it needs to send data. The routes to active destinations

will expire after some time of inactivity, during which the network is not being used.

Hybrid: This type of routing protocols combines features of the above two categories.

Nodes belonging to a particular geographical region or within a certain distance from

a concerned node are said to be in the routing zone and use table driven routing

protocol. Communication between nodes in different zones will rely on the on-

demand or source-initiated protocols.

In the rest of this chapter, I will give an overview of two of the most common routing

protocols used in mobile ad hoc network: Dynamic Source Routing protocol (DSR) and

Ad hoc On-demand Distance Vector routing protocol (AODV)

3.4 DYNAMIC SOURCE ROUTING PROTOCOL (DSR)

The Dynamic Source Routing Protocol is one of the on-demand routing protocols,

and is based on the concept of source routing. In source routing, a sender node has in the

packet header the complete list of the path that the packet must travel to the destination

node. That is, every node in the path just forwards the packet to its next hop specified in

the header without having to check its routing table as in table-driven routing protocols.

Besides, the nodes don’t have to periodically broadcast their routing tables to the

neighboring nodes. This saves a lot of network bandwidth. The two phases of the DSR

operation are described below:

45

3.4.1 ROUTE DISCOVERY PHASE

In this phase, the source node searches a route by broadcasting route request

(RREQ) packets to its neighbors. Each of the neighbor nodes that has received the RREQ

broadcast then checks the packet to determine which of the following conditions apply:

(a) Was this RREQ received before ? (b) Is the TTL (Time To Live) counter greater than

zero? (c) Is it itself the destination of the RREQ? (d) Should it broadcast the RREQ to its

neighbors? The request ids are used to determine if a particular route request has been

previously received by the node. Each node maintains a table of RREQs recently

received. Each entry in the table is a <initiator, request id> pair. If two RREQs with the

same <initiator, request id> are received by a node, it broadcasts only the one received

first and discards the other. This mechanism also prevents formation of routing loops

within the network. When the RREQ packet reaches the destination node, the destination

node sends a reply packet (RREP) on the reverse path back to the sender. This RREP

contains the recorded route to that destination.

Figure 3.2 shows an example of the route discovery phase. When node A wants

to communicate with node G, it initiates a route discovery mechanism and broadcasts a

request packet (RREQ) to its neighboring nodes B, C and D as shown in the figure.

However, node C also receives the same broadcast packets from nodes B and D. It then

drops both of them and broadcasts the previously received RREQ packet to its neighbors.

The other nodes follow the same procedure. When the packet reaches node G, it inserts

its own address and reverses the route in the record and unicasts it back on the reversed

path to the destination which is the originator of the RREQ.

The destination node unicasts the best route (the one received first) and caches the

other routes for future use. A route cache is maintained at every node so that, whenever a

node receives a route request and finds a route for the destination node in its own cache,

it sends a RREP packet itself instead of broadcasting it further.

46

FIG 3.4: ROUTE DISCOVERY IN DSR

3.4.2 ROUTE MAINTENANCE

The route maintenance phase is carried out whenever there is a broken link

between two nodes. A broken link can be detected by a node by either passively

monitoring in promiscuous mode or actively monitoring the link. As shown in Figure 3.3,

when a link break (F-G) happens, a route error packet (RERR) is sent by the intermediate

node back to the originating node. The source node re-initiates the route discovery

procedure to find a new route to the destination. It also removes any route entries it may

have in its cache to that destination node. DSR benefits from source routing since the

intermediate nodes do not need to maintain up-to-date routing information in order to

route the packets that they receive. There is also no need for any periodic routing

advertisement messages.

47

FIG 3.5: ROUTE MAINTENANCE IN DSR

3.5 AD-HOC ON-DEMAND DISTANCE VECTOR (AODV)

ROUTING PROTOCOL

To find routes, the AODV routing protocol uses a reactive approach and to

identify the most recent path it uses a proactive approach. That is, it uses the route

discovery process similar to DSR to find routes and to compute fresh routes it uses

destination sequence numbers. The two phases of the AODV routing protocol are

described below.

3.5.1 ROUTE DISCOVERY

In this phase, RREQ packets are transmitted by the source node in a way similar

to DSR. The components of the RREQ packet include fields such as the source identifier

(SId), the destination identifier (DId), the source sequence number (SSeq), the destination

sequence number (DSeq), the broadcast identifier (BId), and TTL. When a RREQ packet

is received by an intermediate node, it could either forward the RREQ packet or prepare a

Route Reply (RREP) packet if there is an available valid route to the destination in its

48

cache. To verify if a particular RREQ has already been received to avoid duplicates, the

(SId, BId) pair is used. While transmitting a RREQ packet, every intermediate node

enters the previous node’s address and its BId. A timer associated with every entry is also

maintained by the node in an attempt to delete a RREQ packet in case the reply has not

been received before it expires.

When a node receives a RREP packet, the information of the previous node is

also stored in it in order to forward the packet to it as the next hop of the destination. This

plays a role of a “forward pointer” to the destination node. By doing it, each node

contains only the next hop information; whereas in the source routing, all the

intermediate nodes on the route towards the destination are stored.

Figure 3.5 depicts an example of route discovery mechanism in AODV. Suppose

that node A wishes to forward a data packet to node G but it has not an available route in

its cache. It then initiates a route discovery process by broadcasting a RREQ packet to all

its neighboring nodes (B, C and D).

FIG 3.6: ROUTE DISCOVERY IN AODV

49

All the SId, DId, SSeq, DSeq, BId, and TTL fields are inserted in the RREQ packet.

When RREQ packet reaches to nodes B, C and D, these nodes immediately search their

respective route caches for an existing route. In the case where no route is available, they

forward the RREQ to their neighbors; otherwise a comparison is made between the

destination sequence number (DSeq) in the RREQ packet and the DSeq in its

corresponding entry in the route cache. It replies to the source node with a RREP packet

consisting of the route to the destination in the case the DSeq in the RREQ packet is

greater. In Figure 2.4, node C gets a route to G in its cache and its DSeq is greater when

compared with that in the RREQ packet.

3.6 OLSR-INRIA

The Optimized Link State Routing (OLSR) protocol was designed by the French

National Institute for Research in Computer Science and Control (INRIA) for mobile ad-

hoc networks. It is a proactive routing protocol that employs an efficient link state packet

forwarding mechanism called multipoint relaying on its way to optimize pure link state

routing protocol. There is a two way optimization. One by reducing the size of the control

packets and other by reducing the number of links that are used for forwarding link state

packets. The reduction in the size of the link state packets is made by declaring only a

subset of the links in the link state updates which are assigned the responsibility of packet

forwarding known as Multipoint Relays. Periodic link state updates are facilitated by the

optimization done by multipoint relaying facilities. No control packet is generated on the

event of a link break or addition of a new link by the link state update mechanism which

achieves higher efficiency when operating in a highly dense network.

50

FIG 3.7: ROUTE OLSR.

51

3.7HYBRIDS - ZRP

FIG 3.8:  ZONES A PRO-ACTIVE ROUTING PROTOCOL IS USED WHILE A

RE-ACTIVE PROTOCOL IS USED BETWEEN ZONES.

Hybrid protocols seek to combine the proactive and reactive approaches. An

example of such a protocol is the Zone Routing Protocol (ZRP). ZRP divides the

topology into zones and seek to utilize different routing protocols within and between the

zones based on the weaknesses and strengths of these protocols. ZRP is totally modular,

meaning that any routing protocol can be used within and between zones. The size of the

zones is defined by a parameter r describing the radius in hops. Figure 3.6 illustrates a

ZRP scenario with r set to 1. Intra-zone routing is done by a proactive protocol since

these protocols keep an up to date view of the zone topology, which results in no initial

delay when communicating with nodes within the zone. Inter-zone routing is done by a

reactive protocol. This eliminates the need for nodes to keep a proactive fresh state of the

entire network.

52

ZRP defines a technique called the Border cast Resolution Protocol (BRP) to

control traffic between zones. If a node has no route to a destination provided by the

proactive inter-zone routing, BRP is used to spread the reactive route request.

Figure 3.7 illustrates the different components of ZRP.

FIG 3.9: THE DIFFERENT COMPONENTS OF THE ZONE ROUTING

PROTOCOL.

3.8 SECURITY AWARE ROUTING PROTOCOLS

MANETs have certain unique characteristics that make them vulnerable to several

types of attacks. Since they are deployed in an open environment where all nodes co-

operate in forwarding the packets in the network, malicious nodes are difficult to detect.

Hence, it is relatively difficult to design a secure protocol for MANET, when compared

to wired or infrastructure-based wireless networks. This section discusses the security

goals for an ad hoc network. Sample attacks and threats against existing MANET routing

protocols are then discussed. I then discuss the working of two secure routing protocols

to address these threats, OLSR and SAODV.

53

3.8.1 SECURITY GOALS

To secure the routing protocols in MANETs, researchers have considered the

following security services: availability, confidentiality, integrity, authentication and

non-repudiation

Availability guarantees the survivability of the network services despite attacks. A

Denial-of-Service (DoS) is a potential threat at any layer of an ad hoc network.

On the media access control layer, an adversary could jam the physical

communication channels. On the network layer disruption of the routing operation

may result in a partition of the network, rendering certain nodes inaccessible. On

higher levels, an attacker could bring down high-level services like key

management service.

Confidentiality ensures that certain information be never disclosed to

unauthorized entities. It is of paramount importance to strategic or tactical

military communications. Routing information must also remain confidential in

some cases, because the information might be valuable for enemies to locate their

targets in a battlefield.

Integrity ensures that a message that is on the way to the destination is never

corrupted. A message could be corrupted because of channel noise or because of

malicious attacks on the network.

Authentication enables a node to ensure the identity of the peer node. Without

authentication, an attacker could masquerade as a normal node, thus gaining

access to sensitive information.

Non-repudiation ensures that the originator of a message cannot deny that it is

the real originator. Non-repudiation is important for detection and isolation of

compromised nodes.

The networking environment in wireless schemes makes the routing protocols

vulnerable to attacks ranging from passive eavesdropping to active attacks such as

impersonation, message replay, message littering, network partitioning, etc.

Eavesdropping is a threat to confidentiality and active attacks are threats to availability,

54

integrity, authentication and non-repudiation. Nodes roaming in an ad hoc environment

with poor physical protection are quite vulnerable and they may be compromised. Once

the nodes are compromised, they can be used as starting points to launch attacks against

the routing protocols.

3.8.1.1 ATTACKS AND EXPLOITS ON THE EXISTING PROTOCOLS

In general, the attacks on routing protocols can generally be classified as routing

disruption attacks and resource consumption attacks. In routing disruption attacks, the

attacker tries to disrupt the routing mechanism by routing packets in wrong paths; in

resource consumption attacks, some non-cooperative or selfish nodes may try to inject

false packets in order to consume network bandwidth. Both of these attacks are examples

of Denial of Service (DoS) attacks. Figure 3.1 depicts a broader classification of the

possible attacks in MANETs.

FIG 3.10: CLASSIFICATION OF ATTACKS ON MANET ROUTING

PROTOCOLS

55

CHAPTER 4

SYSTEM ARCHITECTURE

4.1 TECHNICAL APPROACH:

Uses the Open Access Research Test bed for Next-Generation Wireless Networks

(ORBIT), which consists of open API wireless terminals, forwarding nodes,

access points, switches and routers, to evaluate different approaches both in terms

of protocol functionality and software performance.

Compatible upgrades to WLAN protocols for service features such as flow QoS

and multicasting; interworking (global roaming, handoff, etc.) of multiple radio

link technologies such as Bluetooth, 802.11, GPRS and 3G/WCDMA.

Self-organizing ad-hoc network protocols for discovery and routing, with

particular focus on a hierarchical 802.11b architecture consisting of mobile nodes

(MN), radio forwarding nodes (FN) and access points (AP).

Theoretical analysis of the capacity and scaling properties of the three-tier

hierarchical hybrid wireless network, and system evaluation for an 802.11-based

hierarchical network.

Cross-layer approaches to MAC, routing and transport in ad-hoc network

scenarios.

Global Control Plane (GCP) approach to help disseminate control information

among ad-hoc nodes and facilitate cross-layer algorithms such as the integrated

routing/MAC scheduling algorithm and cross-layer transport protocol.

Content delivery techniques for mobile users, including those based on proactive

Infostations caching and novel semantic routing techniques. [This project involves

collaboration with Semandex Networks, Princeton, NJ

56

FIG 4.1: INTERNET SYSTEM ARCHITECTURE

4.2 TECHNICAL RATIONALE:

Mobile networks have traditionally been designed via extensions of existing fixed

network protocols to support key mobility functions such as location management,

authentication and handoff. Typically, these protocols were used in the context of

homogeneous vertical architectures in which a single service such as GSM or 3G is

provided to large numbers of mobile users. With the emergence of various new short-

range and medium-range wireless data networks (such as Bluetooth and WLAN), there is

a need for a more horizontal network architecture that accommodates heterogeneous

radio links and permits evolution of mobile network services to include basic mobility

features as well as newer requirements such as self-organization, ad-hoc routing, QoS,

multicasting, content caching, etc.

Such “4G” wireless networks can be realized with an IP-based core network for

global routing along with more customized local-area radio access networks that support

features such as dynamic handoff and ad-hoc routing.

57

4G is all about an integrated global network based on an open-systems approach.

Integrating different types of wireless networks with wireline backbone networks

seamlessly and the convergence of voice, multimedia, and data traffic over a single IP-

based core network will be the main focus of 4G. With the availability of ultrahigh

bandwidth of up to 100 Mbps, multimedia services can be supported efficiently.

Ubiquitous computing is enabled with enhanced system mobility and portability support,

and location-based services and support of ad hoc networking are expected. The

illustration below shows the networks and components within the 4G network

architecture.

FIG 4.2: 4G NETWORK ARCHITECTURE

58

4.3 STRUCTURE CHART

FIG 4.3: MANET ROUTING PROTOCOLS

Survey of applications of MANET : We shall now get an overview of different types of

MANET and their uses.

4.3.1 PURE GENERAL PURPOSE MANET

The mostly discussed application scenario for pure general-purpose MANET is

Battlefield or disaster-recovery networks. However, these kinds of networks have not yet

achieved the envisaged impact in terms of real world implementation and industrial

deployment.

59

AD-Hoc Mobile routing protocols

On demand driven reactiveHybridTable Driven proactive

DSRABRZRPWRPDSDV

RDMBRCBRPSTARCGSR

AODVTORA

4.3.2 MESH NETWORKS

Mesh networks are built upon a mix of fixed and mobile nodes interconnected via

wireless links to form a multihop ad hoc network. Unlike pure MANETs, a mesh network

introduces a hierarchyin the network architecture by adding dedicated nodes (called mesh

routers) that communicate wirelessly to construct a wireless backbone. An example is

MIT Roofnet providing the city of Boston, with broadband access with an 802.11b-based

wireless network backbone infrastructure.

Opportunistic Networking (Delay Tolerant Networking)

(I)POCKET SWITCHED NETWORKS IN THE HAGGLE PROJECT

It targets solutions for communication in autonomic/opportunistic networks. In

this framework, researchers are studying the properties of Pocket Switched Networks

(PSNs), i.e., opportunistic networks that can exploit any possible encountered device

(e.g., cell phones and PDAs that users carry in their pockets) to forward messages.

(II)WILDLIFE MONITORING

Wildlife monitoring is an interesting application field for opportunistic networks.

It focuses on tracking wild species to deeply investigate their behavior and understand the

interactions and influences on each other, as well as their reaction to the ecosystem

changes caused by human activities.

(III)VEHICULAR AD HOC NETWORKS

VANETs use ad hoc communications for performing efficient driver assistance

and car safety. The communications include data from the roadside and from other cars.

VANET research aims to supply drivers with information regarding obstacles on the road

and emergency events, mainly due to line-of-sight limitations and large processing

delays. VANET can be used to communicate premonitions, notification of emergencies,

and warnings about traffic conditions.

60

(IV) WIRELESS SENSOR NETWORKS (WSN)

Benefit from the advances in computing technology, which led to the production

of small, wireless, battery powered, smart sensor nodes. These nodes are active devices

with computing and communication capabilities that not only sample real world

phenomena but also can filter, share, combine, and operate on the data they sense.

The general process of creating a simulation can be divided into several steps:-

Topology definition:- To ease the creation of basic facilities and define their

interrelationships, ns-3 has a system of containers and helpers that facilitates this

process.

Model usage:- Models are added to simulation (for example, UDP, IPv4, point-

to-point devices and links, applications); most of the time this is done using

helpers.

Node and link configuration:- Models set their default values (for example, the

size of packets sent by an application or MTU of a point-to-point link); most of

the time this is done using the attribute system.

Execution:- Simulation facilities generate events, data requested by the user is

logged.

Performance analysis:-  After the simulation is finished and data is available as

a time-stamped event trace. This data can then be statistically analysed with

tools like R to draw conclusions.

Graphical Visualization:-  Raw or processed data collected in a simulation can

be graphed using tools like Gnuplot, matplotlib or Xgraph. Xgraph is the

plotting tool bundled with many of the installation packages.

61

4.4 FRONT END DESIGN

FIG 4.4: FLOW CHART OF ROUTING PROTOCOL

62

Start

Broadcast Packets (BP)

AuthenticationNeighbor discovery and

exchange of ID

Cluster maintenance by detecting events

Received NBR Info ?

Data aggregation at CH & Upload at BP

Create neighbor table

Wait for Time T (stop)

Wait for Time T (boostrap) Receive CH &join

Selected CH by CH Transmit CH

Counter Expired

Compute counter weight values

Stop

The Secure Ad hoc On-Demand Distance Vector (SAODV) protocol was

proposed to answer the challenge of securing a MANET network. SAODV is an

extension of the AODV routing protocol, and it can be used to protect the route discovery

mechanism by providing security features like integrity, authentication and non-

repudiation.

SAODV assumes that each ad hoc node has a signature key pair from a suitable

asymmetric cryptosystem. Further, each node is capable of securely verifying the

association between the address of other node and the public key of that node. A key

management scheme is needed for SAODV. Two mechanisms are used to secure the

AODV messages:

Digital signatures to authenticate the non-mutable fields of the messages, and

Hash chains to secure the mutable hop count field of the message.

For the non-mutable fields, authentication can be performed in a point-to-point

manner, but the techniques cannot be applied to the mutable information. Route error

messages are protected in a different manner because of a big amount of mutable

information. According to the author, it is not important which node started the route

error and which nodes are just forwarding it. The important information is that a neighbor

node is informing other nodes that it is not able to route messages to certain destinations

anymore. Therefore, every node (generating or forwarding a route error message) uses

digital signatures to sign the whole RERR message and that any neighbor that receives

RERR verifies the signature. The RREQ and RREP have the following extension fields

63

TABLE 4.1: HASH FUNCTION

Value Hash function

0 Reserved

1 MD5HMAC96

2 SHA1HMAC96

3 – 127 Reserved

128 – 255 Implementation dependent

4.5 ROUTE DISCOVERY

TESLA handles the authentication of RERR messages in a way similar to how the

RREQ messages are handled. In order to avoid the injection of invalid route errors

(RERR) into the network by any node other than the node that sees a broken link, each

node on the return path to the source node just forwards the RERR. On the other hand

TESLA authentication is delayed, so all the nodes on the return path buffer the error but

do not process it until it is authenticated. Later, the node that saw the broken link

discloses the key and sends it over the return path, which enables nodes on that path to

authenticate the buffered error message. The RERR contains six fields

FIG 4.5: ROUTE REQUEST AND ROUTE REPLY

64

4.5.1 CHARACTERISTIC OF MANET

TABLE 4.2: SURVEYING DIFFERENT TECHNIQUES WE DEFINE THE ADVANTAGES AND DISADVANTAGES OF TECHNIQUES

Techniques Advantages/ Merits Disadvantages

/Future

Improvement

Direction

MANET, AODV,

Trusted Networks;

Trust Model

The proposed approach is the

extension of existing AODV

routing protocol for creating

secure route for communication.

Proposed modifications are in

acceptable limit. With this

minimum overhead, we can easily

eliminate the malicious node as

well as they can establish a best

trusted route between source and

destination.

Using simulation results,

the performance of this

protocol is not sufficient

justified. In the future, it

will be incorporate with

other MANET routing

protocols.

DAAODV, Secure

Routing Protocol

They presented a secure ad hoc

routing protocol which can

prevent most attacks including

worm-hole attacks, vertex cut

attacks, and traffic analysis

attacks, and adopt a new efficient

signing and verifying scheme

preventing DoS attacks.

This protocol doesn't use

TTP, and doesn't add

much overhead in ns-2

simulation. In future

work is to make a fine-

grained construction of

the routing software, as

the design of DAAODV

on software level is a

little coarsegrained.

65

Multipath Routing, Ad-

hoc Networks, AODVsec

The results show that AODVsec

outperforms traditional multipath

routing on ensuring security. As a

common case, attacker cannot

intercept all the paths, AODVsec

avoids maliciously accessing a

entire data packet, so it improves

system's security with negligible

routing overhead.

The AODVsec still has

some imperfect points.

As a future work, it will

need to focus on

designing the

synchronization control

mechanism to solve this

problem .

WirelessSsecurity1,;

MANE, IEEE 802.11b4

The efficient security algorithm

ES-AODV enhances the security

in ad hoc wireless networks.

According to the analysis of the

results obtained from extensive

simulation, it concludes that the

secure routing solution scales well

to both mobility and network size.

The routing protocol

performs Does not better

than the existing secure

AODV routing protocol

with increased mobility

in the network. It should

be improve in future

extension .

MANET, Routing,

Security

In the implementation of such

routing protocols, the need is to

eliminate the shortcoming of these

protocols by evaluating

performance of them on a

simulation platform. To minimize

the associated overhead like

delay, routing overhead demands

an intensive optimization in both

the protocols.

In future it will require

more specifically

SAODV to decrease the

processing requirements

to tackle hash chains and

digital signatures to

implement the security.

66

MANET, SecureAODV This paper, presents the protocol

being proposed which utilizes the

dual cooperative mobile agents

and stationary agents for routing

in dynamic networks as MANET.

Every mobile agent computes the

transmission capacity of all the

nodes so that Routing Agent

System (RAS) can take the

efficient reliable decision which

routing path is more efficient and

reliable.

The transmission

capacity factor into the

networking as MANET

of the protocol will need

to improve in future.

TABLE 4.3: COMPARISON BETWEEN MANET-PROTOCOL

67

FIG 4.6: SOFTWARE ARCHITECTURE OF THE AODV

The component called AODV defines the main flow of control inside the AODV

routing daemon. The control flow is based on an event-driven design. The set of possible

events include reception of routing control packets, expiration of various timers, and

reception of route requests on the ASL socket. Possible actions include sending out

packets, setting new timers and updating various data structures. The daemon program is

essentially a big select() loop which monitors various file descriptors for the events and

takes the appropriate actions. This component also initializes ASL by calling the

functions int route_add() and open\_route\_request().

68

The RREQ, RREP and RERR components take care of both generating as well as

processing incoming route requests, route replies and route error packets respectively.

The Routing Table component (routeTable) handles updates to the aodv routing table as

well as to the kernel routing table. It also maintains a route cache using the aodv-helper

module through the corresponding API function query_route_idle_time_aodv(), as

explained in the next subsection. The Pending Route Request component

(rreqPendingList) implements the expanding ring search and RREQ retransmission

features of the AODV routing protocol. The Forward Route Request component ensures

that a node does not process a particular RREQ packet multiple times, by storing a list of

recently seen RREQ packets. The Local Repair component attempts to repair links

locally and the Blacklist component takes care of routing in the presence of uni-

directional links. Finally, the TimerQueue component maintains various AODV timers

including reboot timer, periodic refresh timer, hello timer and rreq retransmission timer.

4.5.2 A SPLIT DESIGN

As we have explained earlier, due to the inseparable forwarding and routing

functions, there are usually two ways to implement such protocols: a complete in-kernel

approach, and a complete user-space approach. Both approaches have pros and cons. A

complete user-space approach will be inefficient for the forwarding function, but an in-

kernel approach is different to maintain, different to modify, and different to port to other

operating systems.

In our implementation, we attempt a split-system approach. The idea is to

segregate the forwarding and routing functions to some extent, even though they are

intermixed in the protocol design. We believe that the core of the source-routing based

forwarding activities, i.e., to send a data packet to the next-hop based on its DSR header,

should be as efficient as possible and reside inside the kernel. We call this the source

forwarding function. The majority of other source routing activities, which are induced

by source forwarding, need to be flexible and can reside in user-space.

69

FIG 4.7: SPLIT DESIGN

70

CHAPTER 5

EXPERIMENTAL SETUP

5.1 SIMULATION TOOL

One common method to conduct research in the networking and security fields is

to simulate and evaluate the protocol(s) in various scenarios. Fortunately, there are

various computer simulation applications that are available for doing those tasks, such as

NS-2, OPNET, GLOMOSIM, etc. My thesis is heavily based on the implementation and

experiments in the OPNET simulation environment. OPNET Modeled was chosen as a

simulation environment because it is one of the leading environments for network

modeling and simulation. It supports large number of built-in industry standard network

protocols, devices, and applications. In addition, its programming library helps

researchers to easily modify the network elements and measure their performance in the

simulation environment. OPNET also provides rich data analysis features.

5.2 OPNET ARCHITECTURE

OPNET provides a comprehensive environment to model and do performance

evaluation of networks and distributed systems. The OPNET package includes numbers

of tools. Those tools fall into three categories corresponding to the three phases of

modeling and simulation projects: Specification, Simulation and Data Collection, and

Analysis. These phases should necessarily be in sequence and form a simulation cycle as

in Figure 4.1.

OPNET uses the concept of modeling domains to represent its modeling

environments, and graphical editors for editing the Network, Node and Process models.

Specifically, there are several editors in OPNET: project editor, node editor, process

editor, external system editor, link model editor, packet format editor, Interface Control

Information editor, and probability density function editor.

71

FIG 5.1: SIMULATION CYCLE IN OPNET

Network Domain is used to define the network topology of a communication network.

The communicating entities are called nodes. Network domain is created by using the

Project editor tool of the OPNET modeler.

Node Domain describes nodes’ internal architecture in terms of functional elements in

the node and data flow between them.

Process defines the behavior of processes, including protocols, algorithms and

application, specified using infinite state machines and an extended high-level language.

External System specifies the interfaces to the models provided by other simulators

running concurrently with an OPNET simulation (a co-simulation).

72

5.3 NETWORK SIMULATOR

Network simulator 2 is the result of an on-going effort of research and development

that is administrated by researchers at Berkeley. It is a discrete event simulator targeted at

networking research. It provides substantial support for simulation of TCP. Routing, and

multicast protocols.

The simulator is written in C++ and a script language called OTcl2. Ns uses an Otcl

interpreter towards the user. This means that the user writes an OTcl script that defines

the network (number of nodes, links), the traffic in the network (sources, destinations,

type of traffic) and which protocols it will use. This script is then used by ns during the

simulations. The result of the simulations is an output trace file that can be used to do

data processing (calculate delay, throughput etc) and to visualize the simulation with a

program called Network Animator (NAM). See Appendix C for a screenshot of NAM.

NAM is a very good visualization tool that visualizes the packets as they propagate

through the network. An overview of how a simulation is done in

Ns

The current version of the Network simulator does not support mobile wireless

environments. The Network simulator alone is only intended for stationary networks with

wired links. This caused us some problems in the beginning of this master thesis. We

needed mobility and therefore started to design and implement a mobility model that

would extend the simulator. We also started to implement the AODV protocol. This

implementation of AODV is compatible with NAM and therefore gives a good picture of

how AODV behaves. It is very easy to follow for instance the route discovery procedure.

About two months later, in August 1998. two separate mobility extensions were released.

These extensions had everything that we wanted from an extension, so we decided to use

one of them. This however meant that the implementation of AODV that we made earlier

no longer was compatible and had to be ported.

73

5.3.1 AODV

We have implemented the AODV protocol The implementation is done accord to

the AODV draft released in August 1993. It must however be noted that a new version of

the draft was released in the end of November 1998. The new draft contains some

changes that would enhance the performance. These changes that affect the unicast

routing part is primarily:

• Reduced or complete elimination of hello messages.

• Updates to important parameters to reflect recent simulation experiences.

To be able to test how the hello messages and link layer support affects the

behavior of the protocol we have implemented three versions:

• AODV with only IP-based hello messages

• AODV with only Link Layer notification of broken links

• AODV with both IP-based hello messages and Link layer notification of broken links

The implementation of the different versions lias some major differences that will affect

the performance. First of all AODV with only MAC-layer support will not get the routes

to the neighbors installed in the routing table, neither will it update the routes to the

neighbor who forwarded a message to you. Both AODV versions that have hello

messages will have this neighbor detection process that keeps track of the neighbors. This

means that the protocols with this feature will have more information in the routing

tables. Without this support buffering of the packets may be necessary while a request is

sent out in search for a node that could be a neighbor. It must however be noted that the

removal of hello messages somewhat changes the behavior of the AODV protocol. The

hello messages add overhead to the protocol, but also give us some prior knowledge of

link breakages. Removing the hello messages makes the protocol completely on-demand,

broken links can only be detected when actually sending something on the broken link.

74

The DSR implementation that was included in the mobility extension used a

sendbuffer that buffered all packets that the application sent while the routing protocol

searched for a route. To get a fair comparison of the protocols we implemented the same

feature for AODV. This buffer can hold 64 packets and packets are allowed to stay in the

buffer for 8 seconds.

The parameters that can be adjusted for AODV and the values we have used is .

Some of these parameters are very important and affects the performance of the protocol

in drastic ways. The hello interval is maybe the most important parameter when dealing

with AODV that uses hello messages. If the interval is too long, link breakages would not

be detected fast enough, but if the interval is to short, a great amount of extra control

overhead would be added. Most of the parameters in Table 3 are obvious. The maximum

rate for sending replies prevents a node to do a triggered route reply storm. This means

that AODV in each node is only allowed to send one triggered RREP per second for each

broken route. This could for instance happen if a forwarding node receives a lot of data

packets that the node no longer has a route for. In this case the node should only send a

triggered RREP. as a response to the first data packet and if the node keeps receiving data

packets after that, a triggered RREP is only allowed to be sent once per second.

TABLE 5.1: CONSTANTS USED IN THE AODV IMPLEMENTATION

.

Parameter Value

Hello interval 1,5 s

Active route timeout 300 s

Route reply lifetime 300 s

Allowed hello loss 2

Request retries

Time between retransmitted requests 3 s

Time to hold packets awaiting routes 8 s

75

5.3.2 DSR

The DSR implementation that came with the extension uses promiscuous mode (i.e.

eavesdropping), which means that the protocol learns information from packets that it

overhears. The question is how realistic this is in a real environment. In a real case

scenario we will probably have some sort of encryption, probably IP-Sec that uses IP-Sec

tunneling to transport messages. We have made some small change to DSR that makes it

possible to turn the eavesdropping feature on and off. The parameters that are

configurable for DSR are shown in These values are the values specified in the DSR draft

and have not been changed. The no propagating timeout is the time a node waits for a

reply for a no propagating search. A no propagating search is a request that first goes to

the neighbors. If the neighbors do not answer in this specified amount of a tune, a new

request that will be forwarded by the neighbors will be sent. The send buffer in the DSR

can hold 64 packets and the packets are allowed to stay in the buffer for 30 seconds

FIG 5.2: CONSTANTS USED IN THE DSR

Parameter Value

Time between retransmitted requests 500 ms

Size of source route header carrying n addresses 4n + 4 bytes

Timeout for no propagating search 30 ms

Time to hold packets awaiting routes 30 s

5.3.2.1 FLOODING

We have implemented a simple flooding protocol that simply floods all user data

packets to all nodes m the network. To have some sort cleverness in this flooding and

avoiding data to bounce back and forth we use a sequence number in each packet. This

sequence number is incremented for each new packet.

76

Each node keeps track of (source IP, sequence number) for all destinations and

does not process a packet if the packet has a sequence number smaller than the stored

sequence number. The idea was to do the simulations on the flooding protocol and

compare the results with the results for the routing protocols. After some initial

simulations on flooding this plan was abandoned. The simulations took too long to

complete. The reason is that flooding generates too many packets (events in the

simulator).

5.4 OPNET MODELER WIRELESS SUPPORT

The Wireless module in OPNET provides a flexible and scalable wireless network

modeling environment, including a broad range of powerful technologies. The Wireless

module integrates OPNET’s full protocol stack modeling capability, including MAC,

routing, higher layer protocols, and applications, with the ability to model all aspects of

wireless transmissions, including:

Radio Frequency propagation (path loss with terrain diffraction, fading, and

atmospheric and foliage attenuation)

Interference

Transmitter/receiver characteristics

Node mobility, including handover

The wireless module has rich protocol model suites to optimize the R&D

processes, and more effectively design technologies such as MANET, 802.11, 3G/4G,

Ultra Wide Band, 802.16, Bluetooth, and Transformational Communications systems.

Wireless network planners, architects, and operations professionals can analyze end-to-

end behavior, tune network performance, and evaluate growth scenarios for revenue-

generating network services.

5.4.1 IMPLEMENTING THE PROTOCOLS IN THE OPNET MODELER

77

In this thesis, I have implemented two secure routing protocols, SAODV and

OLSR, in the OPNET Modeler simulation environment, using the Application

Programming Interface functions of the OPNET development kit and the embedded C

language. The malicious feature of a wireless node is integrated into the routing protocol

model, so that each wireless node can be easily switched back and forth between the

normal mode and the malicious mode.

We can use the C/C++ language to implement/modify the behavior of a module.

For easy development, OPNET provides quite a large library with over 400 predefined

functions and procedures .

Figure 5.2 shows steps to add new secure routing protocols OLSR and SAODV

into the OPNET Modeler. OLSR and SAODV are respectively based on the DSR and

AODV protocols, which are supported in OPNET, so I did not have to re-implement the

whole protocols. Instead, I duplicate the original protocols (DSR and AODV) and then

add security features to turn them into the secure versions (that is, OLSR and SAODV).

FIG 5.2: STEPS TO ADD NEW SECURE ROUTING PROTOCOLS INTO

OPNET

Step 2 in Figure 5.2 (Add security features into new protocols) is further

concretized in Figure 5.3. At the origin nodes that generate the routing packets, the

security fields are added into the routing packets at the packet creation phase of the

routing process. These security fields will be verified against the secure conditions at the

intermediate nodes and at the destination node. If the security conditions are not met, the

nodes will discard the routing packets; otherwise they accept the packets and proceed to

next appropriate processing phase. These conditions are defined by each specific protocol

and added at the processing phase of the routing process.

78

FIG 5.3: SECURE CONDITIONS AT THE INTERMEDIATE NODES

TABLE 5.3: HASH CHAIN FUNCTION

Function Name Purpose

initialize_hash (<arguments>) Convert a string into an array of bytes

generate_hash_chain (<arguments>)) Hash an array for a given number of times

generate_signature (<arguments>)) Generate a digital signature based on the

private/public key pair of a wireless node

publickey_extraction (<arguments>)) Get the public key of a wireless node (to

be sent to other nodes)

verify_signature (<arguments>)) Verify the signature of a routing packet

verify_hop_count (<arguments>)) Verify the hop count field contained in a

routing packet

initialize_mac (<arguments>)) Generate a hash value based on the MD5

algorithm

OLSR_generate_hash (<arguments>)) Generate a hash value for the OLSR

protocol

79

OLSR_verify_hash (<arguments>)) Verify the hash values in an OLSR

routing packet

5.4.2 IMPLEMENTING THE ATTACK MODELS IN THE OPNET MODELER

In the simulation, the attack models are implemented as part of the routing

process. Figure 4.4 illustrates how attack models are integrated into the routing processes.

Each wireless node, during the routing process, will check if it itself is a malicious node.

If it is, it will turn on the appropriate attacking process; otherwise, it will process the

routing packets as a normal node.

FIGURE 5.4: PROCEDURE TO INTEGRATE ATTACK MODELS IN THE

ROUTING PROCESS

5.4.3 RUNNING SIMULATIONS IN THE OPNET MODELER AND

COLLECTING EXPERIMENT RESULTS

80

Figure 5.5 shows the steps to run experimental scenarios in OPNET. There are

two ways to collect the experimental data from OPNET. The first approach is to use the

OPNET Statistic Analysis tool. Values such as average number of routing packets,

number of data sent or received over various points during the simulation time, etc., are

collected by this tool. Other values like average number of end-to-end delay of data

packets are dumped into a scalar file. This scalar file needs to be converted into a text file

to be readable by other tools.

FIG 5.5: THE FLOW CHART ILLUSTRATING THE PROCESS OF RUNNING

SIMULATION EXPERIMENTS AND COLLECTING EXPERIMENTAL DATA

TABLE 5.4: IMPLEMENTATION MATRIX OF ROUTING ATTACK

MODELS.

PROTOCOL ATTACK-1 ATTACK-2 ATTACK-3

DSR Route Drop Route modification Route Fabrication

OLSR Route Drop Route modification Route Fabrication

AODV Route Drop Route modification Impersonation

SAODV Route Drop Route modification Impersonation

81

5.5 SCENARIO SETUP

In this thesis, I set up a network with 25 wireless nodes moving at random, each

with various speed between 1 and 10 meters per second, which is the average speed of a

walking person or a running vehicle. This is a medium group that represents some of the

typical scenarios, such as a rescue team working in a disastrous area, a group of moving

vehicles in the city, a squad of soldiers or armored vehicles in an army operation, or a

place of an event. The pause time values represent the movement of the objects. Each of

the objects can move at a random direction, stop for some time (per the pause time), and

then change its direction at random and move again. The traffic pattern models the voice

data transferred from one node to the other. The data is sent at a rate of 2 kbps to

represent compressed voice data. The number of data source nodes is chosen based on the

assumption that a half of the nodes send the data and a half of the nodes receive the data.

The destination of data is determined at random to mimic the real situations. The

simulation scenario is summarized below:

- Mobility Model: Random Waypoint

- Simulation time: 400 seconds

- Network setup:

o Number of nodes: 25

o Mobility model: random mobility

o Simulation Area: 4000m x 4000 m

o Node speed : 1-10 m/second

o Mobility pause time values (seconds): 0, 10, 20, 30, 40, 50, 60, 70, 80, 90,

100.

o Number of data source: 10 nodes–node 8, 9, 11, 13, 14, 15, 17, 22, 23 ,24

o Traffic pattern:

Type of traffic: Constant Bit Rate (voice)

82

Packet size: 512 bytes (or ~ 4096 bits)

Sending frequency: 4 packets/second

Traffic destination: random

To create the malicious environments, five nodes are selected to launch the attacks

discussed in the previous section. The attacks are launched separately with various

numbers of malicious nodes. Table 4.2 shows the nodes assigned to implement the

attacks, given different number of malicious nodes.

TABLE 5.5 MALICIOUS NODE ASSIGNMENTS

Number of

malicious nodes

Malicious nodes assigned

1 node 24

2 node 24, node 3

3 node 24, node 3, node 7

4 node 24, node 3, node 7, node 16

5 node 24, node 3, node 7, node 16, node 18

The order in which malicious nodes are involved in attacking the network remains the

same for each protocol’s evaluation.

83

CHAPTER 6

EXPERIMENTAL RESULTS

6.1 RESULT ANALYSIS:

We have considered two different network scenarios with the first one having 52

nodes with 7 different source and destination pairs (Figure 6.1) and the second one

having 72 nodes with 7 different source and destination pairs (Figure 6.2) respectively.

Qualnet 4.5 network simulator is used to extensively simulate the above mentioned

scenarios. We have taken the packet size to be 512 bytes. User Datagram Protocol (UDP)

is used as the transport layer protocol and Constant Bit Rate (CBR) traffic is used as the

application layer protocol applied between the source and destination. In the first scenario

CBR traffic is applied between seven source destination node pairs namely (3, 40), (5,

38), (13, 47), (17, 49), (19, 46), (28, 35) and (39, 07) respectively as depicted in figure 1

over randomly deployed 52 nodes in the deployment area. In the second scenario

similarly CBR traffic is applied between seven source destination node pairs namely (2,

39), (12, 30), (19, 27), (23, 41), (45, 31), (55, 29) and (65, 16) respectively as shown in

figure 2 over randomly deployed 72 nodes in the deployment area. In both the scenarios

Random Waypoint (RWP) mobility model is considered.

It gives a list of various simulation parameters. We have enhanced both security

and throughput at the same reducing end-to-end delay and jitter in our proposed schemes.

This can be attributed to the fact by taking only links with high SNR value we ensure

reliability, increased throughput and security. Jamming and interfering signals from

intruder or malicious nodes lowers a link's SNR ratio and provides a good indication

about its reliability and security

84

FIG 6.1. NETWORK SCENARIO COMPRISING OF 52 MOBILE NODES AND 7 DIFFERENT SOURCES - DESTINATION TRAFFIC PAIRS.

6.2 EXPERIMENTS IN THE BEGIN ENVIRONMENT

In this phase, the performance data of four routing protocols (DSR, OLSR,

AODV and SAODV) are collected. A scenario is set up for data collection. This scenario

is run 11 times with 11 different values of the mobility pause time ranging from 0 to 100

seconds. The data is collected according to two metrics – Packet Delivery Fraction and

Normalized Routing Load. In general, the actual values of the performance metrics in a

given scenario are affected by many factors, such as node speed, moving direction of the

nodes, the destination of the traffic, data flow, congestion at a specific node, etc.

85

It is therefore difficult to evaluate the performance of a protocol by directly

comparing the acquired metrics from individual scenarios. In order to obtain

representative values for the performance metrics, we decided to take the average values

of multiple simulation runs. The average values of these 11 simulation runs are then

calculated for the two metrics and used as a baseline to evaluate the performance of

routing protocols in malicious environments.

FIG 6.2 CLUSTERING CREATION AND NODE DISTRIBUTED

86

FIG 6.3: PACKET DELIVERY FRACTION VS. PAUSE TIME VALUES IN

BENIGN ENVIRONMENT

As shown in Figure 6.1, the percentage of packets delivered in AODV and

SAODV is fairly close to each other, and both methods exhibit superior performance

(~90% in general). The security features in SAODV lower the performance a little bit.

Actually, the generation and verification of digital signatures depends on the power of the

mobile nodes and causes a delay in routing packet processing. In the simulation

environments, this delay depends on the simulation running machine and is not high

enough to make the significant difference for the PDF metric. On the other hand, the

packet delivery fraction in DSR and OLSR are 20-40% lower than that of

AODV/SAODV across the board given different mobility pause times.

The major difference between AODV and DSR is caused by difference in their

respective routing algorithms. It was reported by other researchers that, in high mobility

and/or stressful data transmission scenarios, AODV outperforms DSR. The reason is that

DSR heavily depends on the cached routes and lack any mechanism to expire stale

routes. In the benign environment of our experiments, the default expiry timer of cached

route for DSR and OLSR is 300 seconds, while this number is 3 seconds for AODV and

SAODV. In respect to the protocol design, these values are kept unchanged through all

the simulation scenarios.

87

Furthermore, DSR and OLSR store the complete path to the destination. Hence,

if any node moves out of the communication range, the whole route becomes invalid. In

MANETs, the nodes are mobile, so route change frequently occurs. Without being aware

of most recent route changes,

The situation is even worse for OLSR, mainly because OLSR relies on the

delayed key disclosure mechanism of TESLA when authenticating packets, including the

RERR packets (see section III.3.1 for details). When an intermediate node in OLSR

notices a broken link, it sends a RERR message to the source node of the data packet.

The source node, however, simply saves the RERR message, because it has not yet

received from the intermediate node the key needed to authenticate the route error. The

source node keeps sending the data until the second route error is triggered, and another

RERR is received. Only then would the previous route error be authenticated, and the

broken link not be used any more. This explains the worse performance of OLSR in

comparison with DSR and other protocols.

88

FIG 6.4: NORMALIZED ROUTING LOAD

Normalized Routing Load of the routing protocols in benign environment

0

0.5

1

1.5

2

2.5

3

3.5

0 10 20 30 40 50 60 70 80 90 100

Pause time (sec)

NR

L

DSR

ARIADNE

AODV

SAODV

FIG 6.5: NORMALIZED ROUTING LOAD VS. PAUSE TIME VALUES IN

BENIGN ENVIRONMENT

89

As shown in Figure 5.2, the NRL metric is, in general, inversely proportional to

the PDF metric (Figure 5.1). A low PDF value (for example, OLSR in Figure 5.1)

corresponds to a high NRL value (Figure 5.2). This relationship between PDF and NRL

is further illustrated in Table 5.1, which lists the average values of the two metrics over

11 simulation runs for each of the four protocols.

6.1 THE “BASELINE” METRICS OF THE FOUR PROTOCOLS

Pause Time

(seconds)

Packet

Delivery

Fraction (%)

Normalized

Routing

Load

DSR 68.41% 1.72

OLSR 54.70% 2.58

AODV 93.45% 1.01

SAODV 92.00% 0.98

The comparison between the normal routing protocols (DSR and AODV) and

their respective secure version (that is, OLSR and SAODV) in benign environments has

been extensively conducted by other researchers. In the next section, I will discuss the

performance of the protocols in various malicious environments.

90

Fig 6.7.Comparision of Jitter for OLSR-INRIA & SOLSR-INRIA, DSR & SDSR and ZRP & SZRP for 52 & 72 Nodes.

FIG 6.6: THROUGHPUT

91

6.2.1 THROUGHPUT

We have measured end to end throughput in Kbits/sec for each source destination

pair over both the network scenarios. A high individual and average throughput is

observed in all the cases by the modified protocols. The result obtained can be attributed

to the fact that due to the selection of the path having highest SNR value the impact of

interference and jamming signals are less and path bandwidth is increased which is

reflected as higher throughput that is desirable for almost every envisaged application of

MANET. A considerable improvement in average throughput is observed in both the

scenario for all routing protocol.

In case of the end-to-end packet delay is calculated as the elapsed time interval

when the packet is sent by the source to the time when it is received at the destination

node. The modified protocols exhibits a low end to end delay every source destination

pair and on the average as well. This can be attributed to the fact due to the selection of

high SNR value paths offering high bandwidth resulting in lower queuing delay at the

intermediate nodes.

The overall end to end delay is reduced which is an important QoS in applications

such as video streaming, live telecast and others. Fig 6 shows the end to end delay for

scenario 1 and scenario 2 as well. A significant reduction in average end to end delay is

observed which makes this type of modified protocol suitable for video streaming

operations.

92

Figure 6.8 . Comparison of End-to-End Delay for OLSR-INRIA & SOLSR-INRIA, DSR & SDSR and ZRP & SZRP for 52 & 72Nodes.

6.2 THROUGHPUT

6.2.2 END TO END DELAY PERFORMANCE

93

End-to-End

Delay

52 Nodes 72 Nodes

(In Sec) Scenario Scenario

OLSR-INRIA 0.818 0.727

SOLSR-INRIA 0.329 0.131

DSR 01.48 1.404

SDSR 0.178 0.235

ZRP 0.185 04.04

SZRP 0.126 0.171

In case of SOLSR-INRIA the End-to-End Delay is decreased by 59% for the first

scenario and 81% for the second scenario. In case of SDSR the End-to-End Delay is

decreased by 87% for the first scenario and 83% for the second scenario. As well as for

SZRP the End-to-End Delay is decreased by 32% for the first scenario and 95% for the

second scenario.

generates an evenly spaced stream, unavoidable jitter is introduced by the network due to

the variable queuing and propagation delays, and packets arrive at the destination with a

wide range of inter-arrival times. The jitter increases at switches along the path of a

connection due to many factors, such as conflicts with other packets wishing to use the

same links, and nondeterministic propagation delay in the data-link layer. In our modified

protocol average jitter decreases for SOLSR-INRIA, SDSR and as well as for SZRP. .

In case of SOLSR-INRIA the Jitter is decreased by 52% for the first scenario and 67%

for the second scenario. In case of SDSR the Jitter is decreased by 84% for the first

scenario and 75% for the second scenario. As well as for SZRP the Jitter is decreased by

68% for the first scenario and 76% for the second scenario

TABLE 6.3: END TO END DELAY

94

Jitter 52 Nodes 72 Nodes

(In Sec) Scenario Scenario

OLSR-INRIA 0.124 0.112

SOLSR-

INRIA

0.059 0.036

DSR 0.497 0.493

SDSR 0.077 0.120

ZRP 0.067 0.264

SZRP 0.021 0.061

FIG 6.9: DELAY VS TIME

95

Fig 6.10: Delivery Ratio

96

6.3 EVALUATION RESULT:

The AODV protocol performance was evaluated with the "Network Simulator 2"

(ns–2), which is one of the most powerful tools used to simulate wired and wireless

network protocols. For our case of study, three simulation scenarios were considered: in

the first one the simulation was carried out in normal conditions, in other words, all the

nodes participated correctly in the routing functions. In the second scenario, one of the

nodes was a malicious node which accomplished the sequence number attack. In the third

scenario, an attack detection module was proposed and it was incorporated in the AODV

protocol and simulated again.

The metrics that we used to evaluate the attack detection module performance are

the following: (1) Packet delivery ratio or percentage (considered as our most important

metric), (2) Number of RREP packets sent by node number 2 (the malicious node), (3)

Accuracy on attack detection, and (4) Average latency of the transmitted packets.

FIG 6.11: PACKET DELIVERY RATIO VS NUMBER OF

CONNECTIONS

97

6.3.1 NUMBER OF RREP PACKETS SENT BY NODE 2 (MALICIOUS NODE)

It shows the number of RREP packets sent by node 2 (the malicious node) versus

the number of connections in normal conditions. In order to evaluate this metric and

observe the behavior of the curves, we have placed the respective graphics on separate

figures. Figures 9 and 10 depict the number of sent RREP packets versus the number of

connections without or with the module incorporated, respectively, and both under attack

conditions.

FIG 6.12: NUMBER OF RREP SENDS BY NODE 2 VS NUMBER OF

CONNECTIONS

The three graphics show a proportional behavior between the number of

connections and the number of RREP packets sent by node 2. This is normal since a great

number of traffic connections in the network provides a greater chance to the malicious

node to send RREP packets. Nevertheless, when the attack takes place the number of sent

RREP messages (false messages in this case) is much bigger than the number of

messages sent under normal conditions.

98

This is because the attack is implemented in such a way that the malicious node

replies with a false RREP to any route request that reaches it.

With the detection module incorporated the number is even bigger; this is because

there is a moment in which the source node discards any RREP it receives (due to broken

links or increments in the sequence number). In that moment there is not an available

route for the source node, which is continuously sending route requests, and that explains

the increment on the number of RREP.

FIG 6.13: NUMBER OF RREP SENDS BY NODE 2 VS NUMBER OF

CONNECTIONS UNDER ATTACKS

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6.3.2 TRANSMITTED PACKETS AVERAGE DELAY

It show the graphics obtained when analyzing the packets' average delay versus

the number of connections and the node mobility for every simulation scenario. We are

including here the possible delays due to buffering during the route discovering delay, the

interface queue, the MAC layer's transmission delay and the time for transferring.

FIG 6.14: AVERAGE DELAY VS NUMBER OF CONNECTIONS

It shows that there is a decrease on the average delay when the protocol in under

attack (compared with the normal operation). It is important to mention that in this case

the average is obtained from a fewer quantity of packets, that is, only those that are

delivered to their destinations. When the detection module is incorporated there is a light

increasing on the average delay due to the time used by the source node in determining

whether it is being attacked or not.

100

FIGURE 6.15: AVERAGE DELAY VS MAX SPEED OF NODE

MOVEMENTS

101

CHAPTER 7

CONCLUSION AND FUTURE WORK

CONCLUSION

From the simulation results it can be concluded that for SOLSR-INRIA, SDSR

and SZRP average throughput increases while average end-to-end delay and jitter

decreases considerably as compared to OLSR-INRIA, DSR and ZRP in both the

scenarios. The modified protocols avoid malicious nodes and noisy links by choosing the

highest SNR path which increases overall network reliability. Random Waypoint (RWP)

mobility model is considered as it encompasses most of the envisaged application areas

of MANETs. We have extensively simulated our methods using QualNet 4.5 network

simulator. As a future work other mobility models and data traffic might be considered.

Intrusion detection methods may be incorporated in the route discovery phase of OLSR-

INRIA, DSR and ZRP for detection of malicious nodes to enhance network reliability.

In this thesis, I have implemented two secure routing protocols, OLSR and

SAODV, based on their respective underlying protocols, DSR and AODV, in the OPNET

simulation environment. I have also simulated four popular network attack models that

exploit the weakness of the protocols. The attack models are used to make malicious

wireless nodes and create various malicious environments, in which the performance of

DSR, AODV, OLSR, and SAODV are evaluated. With three different attack models for

each of the protocols, and with the number of malicious nodes varying from one to five,

totally 65 scenarios are created to evaluate the four protocols.

102

The ultimate goal of a routing protocol is to efficiently deliver the network data

to the destinations; therefore, two metrics, Packet Delivery Fraction (PDF) and

Normalized Routing Load (NRL), are used to evaluate the protocols. In order to get the

accurate experimental results, each scenario is run eleven times in order to calculate the

average value for the two evaluation metrics. Through the collected evaluation metrics

from the various scenarios, the impacts of attacks upon the routing protocols are then

studied. The procedure is summarized below:

First, the four protocols are used in a benign environment, in which there is no

network attack, in order to collect baseline values for the metrics. The differences

amongst baseline values of the protocols are also discussed in order to get better

understanding of each protocol’s operation.

Second, each of the protocols is evaluated in various simulated malicious

environments. The collected metrics are compared with the respective baseline values, in

order to assess the impact of a particular network attack on the protocol operation. Based

on the results we’ve collected, we conclude that, in all the malicious environments,

normal routing protocols (DSR and AODV) can not guarantee to deliver data to the

destinations as well as in the benign environments. In other words, the data is redirected

or discarded due to the attacks on the routing protocol. When the number of malicious

nodes increases, the number of received data packets decreases. For the secure versions

of the routing protocols (OLSR and SAODV), they are designed to detect the changes in

routing packets; hence, even under attacks, they are still able to deliver the data to the

destinations. However, under specific attacks like route fabrication attack for OLSR and

impersonation attack for SAODV, the protocol requires the existence of a specific

security mechanism, in order to maintain the normal operation. That is the key

management center for SAODV and the secure cached routes for OLSR.

Another conclusion is that the mobility model of the malicious nodes affects the

number of data packets to the destinations. Preliminary analysis and discussions of this

issue can be found in Chapter VI

103

FUTURE WORK

More research is needed in the following issues:

The OLSR protocol needs to be improved in order for the cached route feature to

be secure and effective in malicious environments.

A public key verification mechanism, such as certificate-based authentication, is

needed for SAODV, in order to verify the binding between the node’s identity and

its public key.

More research is needed in the mobility of the nodes in order to comprehensively

evaluate the impact of the malicious nodes’ movement on the protocol’s

performance.

104

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