4168945 evaluation of the wireless ospf routing protocol

Evaluation of the Wireless OSPF Routing Protocol

January

2008

[The goal of this project is to evaluate by simulation the WOSFP extension. We had used the NS “Network Simulator” for that purpose and had compared different ad hoc routing protocols.]

WOSPF

Imam Muhammad Bin Saud Islamic UniversityCollege of Computer & Information Sciences

Department of Computer Science

Graduation Project


Ayoob Ibraheem Al Ali

Supervisor: Dr.Miled Tezeghdanti 2008


Ayoob Al Ali (2311044)

Evaluation of the WOSPF

Jan 2008

[email protected]

This report is submitted in partial fulfilment on the requirements for the degree of BSc Honours in College of Computer & Information Sciences

Department of Computer Science at Imam Muhammad Bin Saud Islamic University, Saudi Arabia.

ABSTRACTRouting in an Ad Hoc network is always a hot research topic and still an open issue.

Many ad hoc routing protocols had been proposed by the network community and still

no agreement on a giving solution as it is the case for wired networks. Recently,

Boeing and Cisco had proposed the extension of the well known OSPF “Open Shortest


Path First” routing protocol for the wireless word. The proposal suggests an

optimization of the OSPF flooding mechanism for wireless networks. The goal of this

project is to evaluate by simulation this extension. We had used the NS “Network

Simulator” for that purpose and had compared different ad hoc routing protocols.


AcknowledgementsI would like to thank Dr.Miled, my project supervisor, who allowed me to study,

explore, and implement this really interesting project.

I am also grateful to people who helped me through in one way or another, as:

Dr.Humayun Bakht at Liverpool John Moores University, who provide me a good

information about Ad Hoc networks.

All people on the NS-2 mailing list, especially Mathieu Gallissot.

Thanks also go to all open source software developers.


TABLE OF CONTENTSABSTRACT..................................................... ..................................4Acknowledgements....................................................................... ......5Chapter 1 Introduction................................................... .....................8

1. 1 Overview.................................................................... ............81.2 Problem statement.................................................. .................81.3 Project Goals...................................................... .....................91.4 Chapters’ Overview.................................................... .............9

Chapter 2 Wireless Networks..................................................... .......102.1 Definition.................................................... .............................102.2 Wireless types....................................................................... ....10

2.2.1 Infrastructure................................... ...................................102.2.2 Ad Hoc.................................................................. ..............11

Chapter 3 Routing in Mobile Ad Hoc Networks.............................153.1 Introduction............................................................................. ....15

3.2 Ad Hoc Routing Protocols................................................ ........163.2.1 Proactive Protocols............................................ ..............163.2.2 Reactive Protocols......................................... ..................203.2.3 Hybrids Protocols....................................... .....................24

Chapter 4 WOSPF............................................................................ .254.1 Open Shortest Path First (OSPF)................................... ........25

4.1.3 OSPF Standard Header....................................... .............274.2 WOSPF Overview....................................................... ..........29

Chapter 5 Implementation............................................................. ....325.1 Network Simulator (NS2).....................................................325.2 Simulation Scenario and results............................................33

5.2.1 First Scenario:................................................................ ..345.2.2 Second Scenario:.................................... .........................355.2.3 Third Scenario:............................................ ....................365.2.4 Fourth Scenario:................................. .............................385.2.5 Fifth Scenario:.......................................... .......................395.2.6 Sixth Scenario:............................ ....................................415.2.7 Scenario Visualization............................. ........................43

Chapter 6 Conclusion and Future Works.......................................... .45References:.................................................... ...................................47List of symbols and/or abbreviations....................... .........................48


List of FiguresFigure 1: Example of infrastructures mode (Access Point)........................................ ............10Figure 2: Example of Ad Hoc networks................................................................... ..............11Figure 3: Example of hidden terminal problem..................................................................... .12Figure 4: A Request To Send (RTS) and Clear To Send (CTS) scheme . [3] ...........................13Figure 5: Example of DSDV (1).......................................................................... ..................17Figure 6: Example of DSDV (2).......................................................................... ..................17Figure 7: Example of AODV route discovery........................................................... .............21Figure 8: flooding in a wireless network......................................................................... .......29Figure 9: Wireless network with an optimized flooding scheme.................................... ........29Figure 10: before and after implement AOR................................................................ ..........30Figure 11: description of NS-2 (merge between C++ and OTCL)................ .........................31Figure 12: packets received and packet lost.............................................................. .............33Figure 13: CPU utilization Figure 14: Traffic engineering............................ ......................33Figure 15 :packets received and packet lost.............................................................. .............34Figure 16: CPU utilization Figure 17: Traffic engineering............................ ......................35Figure 18: packets received and packet lost.............................................................. .............36Figure 19: CPU utilization Figure 20: Traffic engineering............................ ......................36Figure 21: packets received and packet lost.............................................................. .............37Figure 22: CPU utilization Figure 23 : Traffic engineering ............................ ......................37Figure 24: packets received and packet lost.............................................................. .............38Figure 25: CPU utilization Figure 26 : Traffic engineering ........................... ........................39Figure 27: packets received and packet lost.............................................................. .............40Figure 28-a: CPU utilizationFigure 28-b: Traffic engineering.......................... ....................40Figure 29: scenario of 6 nodes send from node 0 to 5.................................................... ........41Figure 30: scenario of 30 nodes send from node 0 to 5................................................. .........41Figure 31: scenario of 30 nodes randomly motion.................................................. ...............42

Chapter 1Introduction

1 Overview


In a world of increasing mobility, there is a growing need for people to communicate

with each other and have timely access to information regardless of the location of the

individuals or the information. A phone call placed from a commuter train may close a

business deal, remote access to medical records by a paramedic may save a life, or a

request for reconnaissance updates by a soldier with a hand held device may affect the

outcome of a battle. Each of these instances of mobile communications poses an

engineering challenge that can be met only with an efficient, reliable, wireless

communication network. The demand for wireless communication systems of

increasing sophistication and ubiquity has led to the need for a better understanding of

fundamental issues in communication theory and electro magnetic and their

implications for the design of highly-capable wireless systems [1].

Wireless connectivity gives users the freedom of movement they desire. Most of the

wireless networks required an underlying architecture of fixed position: this

architecture in called infrastructure mode. That's means, mobile nodes communicate

directly with access points. In contrast way, the mobile nodes create underlying

architecture for communication between nodes: this architecture is called ad hoc mode.

1.2 Problem statementRouting in an Ad Hoc network is always a hot research topic and still an open issue.

Many ad hoc routing protocols had been proposed by the network community and still

no agreement on a giving solution as it is the case for wired networks. Recently,

Boeing and Cisco had proposed the extension of the well known OSPF “Open Shortest

Path First” routing protocol for the wireless word. The proposal suggests an

optimization of the OSPF flooding mechanism for wireless networks. The goal of this

project is the evaluation by simulation this extension.

1.3 Project Goals

Study OSPF protocol.


Study wireless extensions of the OSPF protocol.

Evaluate by simulation using NS “Network Simulator” the optimization of OSPF

for wireless networks.

Compare WOSPF with some well known ad hoc routing protocols.

1.4 Chapters’ Overview

Chapter 2 Wireless Networks is an overview of wireless technologies and issues

related to computer network.

Chapter 3 Routing in Ad Hoc outlines about some approaches in MANET routing

protocols.

Chapter 4 WOSPF describes the extensions to OSPFv2 needed to support mobile ad

hoc networking.

Chapter 5 Implementation describes our scenarios, simulations and results over some

protocols.

Chapter 6 Conclusions and Future Work Conclusions on the implementation and

suggestions for future work.

Chapter 2Wireless Networks

2.1 Definition


Wireless is a term used to describe telecommunications in which electromagnetic

waves (rather than some form of wire) carry the signal over part or all of the

communication path. Some monitoring devices, such as intrusion alarms, employ

acoustic waves at frequencies above the range of human hearing; these are also

sometimes classified as wireless.

2.2 Wireless types

Wireless networks can operate in two modes:

• Infrastructure • Ad hoc

2.2.1 InfrastructureThese networks are characterized by their use of access points (AP), or base stations.

In addition to acting as a router within the network, an access point can also act as a

bridge connecting, for example, the wireless network to a wired network. GSM, and its

3G counter part UMTS, are examples of well known cellular networks.

Centralized routing and resource management by an AP implies less complexity than

distributed routing. An AP, as opposed to individual nodes, usually possess more

information about the network, and is therefore able to make intelligent routing

decisions.

Figure 1: Example of infrastructures mode (Access Point).

2.2.2 Ad HocAd hoc is a Latin phrase which means "for this purpose". It generally signifies a

solution that has been custom designed for a specific problem ht is non-generalizable

and cannot be adapted to other purposes [11].


2.2.2.1 MANET

MANET is abbreviation of (Mobile Ad Hoc Network), that’s means a collection of

mobile nodes forming short live or temporary networks without the aid of any

centralized structure. All nodes are capable of movement and are connected

dynamically. In this type of network there is no base station that acts as a router,

instead each node functions as a router, forwarding data for other nodes.

Due to the recent advancements and commercial growth in wireless communication

technology, MANET is expected to be very useful for the deployment of temporary

networks in emergency situations such as fire, safety, rescue operations, meetings or

conventions in which persons wish to quickly share information, and data acquisition

operations using autonomous vehicles.

The main challenge of MANET is that the connections between the nodes within the

network are continuously changing. Thus routing protocols must be adaptive and fast

enough to maintain routes in spite of the changing network topology.

Figure 2: Example of Ad Hoc networks.

2.2.2.2 Importance of Ad Hoc Networks

Ad-hoc networks are expected to play an important role in future commercial and

military setting where mobile access to a wired network is either ineffective or

impossible. Potential applications for this class of network include instant network

infrastructure to support collaborative computing in temporary or mobile


environments, emergency rescue networks in disaster, remote control of electrical

appliance, emergency medical situations , communication systems for ITS such as IVC

(Inter-Vehicle Communications) , and mobile access to the global Internet.

Furthermore, ad-hoc networks have the potential to serve as a ubiquitous wireless

infrastructure capable of interconnecting many thousands of devices with a wide range

of capabilities and uses. In order to achieve this status, however, ad-hoc networks must

evolve to support large numbers of heterogeneous systems with a wide range of

application requirements.

2.2.2.3 Issues and Problems in Ad Hoc Networks:

Hidden Terminal Problems

In our figure 3 we see the node B is in range of A and C, but A cannot detect C, and C cannot detect A.

Figure 3: Example of hidden terminal problem.


The typical solution for this so-called “Hidden terminal” problem is that the nodes

coordinate transmissions themselves by asking and granting permission to send and

receive packets. This scheme is often called RTS/CTS (Request To Send/Clear To

Send). The basic idea is to capture the channel by notifying other nodes about an

upcoming transmission. This is done by stimulating the receiving node to output a

short frame so that nearby nodes can detect that a transmission is going to take place.

The nearby nodes are then expected to avoid transmitting for the duration of the

upcoming (large) data frame. The scheme is illustrated in Figure 4.

Figure 4: A Request To Send (RTS) and Clear To Send (CTS) scheme. First, A and C each transmit a packet simultaneously, causing a packet collision at B. Then A

retransmits the packet before C does, thus capturing the channel. [3]

security

As we know the signal is diffused in the air, then everybody is able to receive it. At

present MANET do not have any stick security policy. This could possibly lead active

attackers to easily exploit or possibly disable mobile ad hoc network. By the nature

Mobile ad hoc networks are highly dynamic i.e. topology changes and link breakage

happen quite frequently. We need a security solution which is dynamic too. [6]


Chapter 3 Routing in Mobile Ad Hoc Networks

MANETs are a subset of wireless networks, as they can be viewed as wireless

networks not dependent on existing infrastructure. An overview of routing in MANETs

is given in this chapter, with some details to the most prominent MANET routing

protocols.

3.1 Introduction

The routing is the process that selects paths in a computer network along which to send

data.In infrastructure mode, the routing part is handled by the access point and the

distribution system; every wireless device just has to forward all its traffic to this

access point. But, in Ad Hoc networks, there is no centralises for connections, and,

every device acts as a router.

This scenario is totally new. Adding to this, devices are not fixed, they can be mobile,

contrary to the Internet where every router has “fixed” neighbours (excepts if a link

goes down).

For solving this problem, the IETF (Internet Engineering Task Force), powerful

standardisation authority in the communication world, created the MANET work

group. This group has a mission to create and discuss routing protocols for Ad Hoc

networks. This task is very important, due to the complexity of routing on Ad Hoc

networks.

The work started in January 1999, with the publication of the informational RFC 2501.

This document presents the 4 main constraints for routing on Ad Hoc networks, such as

dynamics topology, bandwidth constraints, energy constraints and low physical

security. The group has then to comply with these constraints in order to build an

efficient algorithm of route calculation. [2]


3.2 Ad Hoc Routing Protocols

There are three classifications of Ad hoc routing protocols, more details in the follow

subsections.

Proactive

The basic manner that the routing table is built before the data has to be sent. That

means these protocols are constantly making requests to their neighbours (if any) in

order to draw a network topology, and then, build the routing table.

Reactive

Reactive protocols are more specific to Ad Hoc networks. Contrary to the proactive

algorithm, they ask their neighbours for a route when they have data to send. If the

neighbours do not have any known route, they broadcast the request, and so on.

Hybrids

A Hybrid protocols will use the two above algorithms. The main goal is to reduce

broadcasts and latency, but improve the dynamism impact. The whole network will be

separated into logical zones, and each zone will have a gateway. Inside each zone, a

reactive protocol will be used. For inter-zone routing, a proactive protocol will be used.

3.2.1Proactive Protocols

As proactive protocols are constantly updating their routing tables in order to be ready

when data has to be sent, they are called table-driven protocols. This type of protocol is

close to wired networks where the same mechanisms are used in order to take routing

decisions. These mechanisms are used for finding the shortest path across the network

topology; it can be the “Link state” method or the “Distance Vector” method.

With the “Link State” method, each node has its own view of the network, including

the states of its own channels. When an event on the channel occurs, the node floods

the network topology with its own new view of the topology. Other nodes which

receive this information use algorithms to reflect changes on the network table.


With the “Distance Vector” routing approach, each node transmits to its close nodes its

vision of the distance which separate it from all the hosts of the network. Based on the

information received by the neighbourhood, each node performs a calculation in order

to define routing tables with the shortest path to all destinations available in the

network.

3.2.1.1 Destination Sequenced Distance Vector (DSDV)

DSDV was one of the first proactive routing protocols available for Ad Hoc networks.

It was developed by C. Perkins in 1994, 5 years before the informational RFC of the

MANET group. It has not been standardised by any regulation authorities but is still a

reference.

3.2.1.1.1 Algorithm

DSDV is based on the Bellman-Ford algorithm. First designed for graph search

applications, this algorithm is also used for routing since it is the one used by RIP. With

DSDV, each routing table will contain all available destinations, with the associated

next hop, the associated metric (numbers of hops), and a sequence number originated

by the destination node.

Tables are updated in the topology per exchange between nodes. Each node will

broadcast to its neighbours entries in its table. This exchange of entries can be made by

dumping the whole routing table, or by performing an incremental update, that means

exchanging just recently updated routes. Nodes who receive this data can then update

their tables if they received a better route, or a new one. Updates are performed on a

regular basis, and are instantly scheduled if a new event is detected in the topology. If

there are frequent changes in topology, full table exchange will be preferred whereas in

a stable topology, incremental updates will cause less traffic.

The route selection is performed on the metric and sequence number criteria. The

sequence number is a time indication sent by the destination node. It allows the table

update process, as if two identical routes are known, the one with the best sequence

number is kept and used, while the other is destroyed (considered as a stale entry).


3.2.1.1.2 Illustration

Let us consider the two following topologies (figure 5 and figure 6). At t=0, the

network is organized as shows figure 5. We suppose at this time the network is stable,

each node has a correct routing table of all destinations.

Figure 5: Example of DSDV (1)

Then, we suppose G is moving, and at t+1, the topology is as shown in figure 6.

Figure 6: Example of DSDV (2)

At this stage, the following events are detected, and actions are taken:

On node C: link with G is broken, the route entry is deleted, and updates are sent to

node D. On node A and F, a new link is detected, the new entry is added to the routing

table and updates are sent to neighbours. On node G, two new links are detected (to A

and F), and one is broken (to C), the routing table is updated and a full dump is sent to

neighbours (as the routing table is entirely changed, a full dump equals an incremental

update).

3.2.1.1.3 Performance

As with every table-driven protocol, DSDV reduces the latency by having a route when

the data has to be sent. But, DSDV presents a few problems, mainly in the route table

update process. One of the major problems is that data is exchanged only between

neighbours, and then, a change in the topology can take time to be spread in the whole

topology. That introduces the notion of route fluctuation. When a node disappears, it

takes time for this change to be reflected in the whole topology. So, if the topology is

dynamic, the routing layer will be unstable until changes are reflected everywhere.

This route fluctuation problem can be demonstrated with the example in 3.2.1.1.2.

Updates are sent after events, links broken and new links. At t+1, the routing protocol


will transmit routing table updates according to the newly detected events. But, once

these updates are processed by nodes D, B and E, nodes C and D still have no routes

for G, and it will take two more updates until the entire topology will be updated on all

nodes.

3.2.1.2 Optimized Linked State Routing (OLSR)

OLSR is another proactive protocol. Initiated by the INRIA, It has been proposed for

standardisation to the IETF with the RFC 3626 in October 2003. As a proactive

protocol (table driven), OLSR is table-driven. The change comparing to other proactive

protocols is in the route updating process. [12]

3.2.1.3 Fisheye State Routing (FSR)

The FSR protocol is based on the “Fisheye” method proposed by Kleinrock and

Stevens. This method was, as the Bellman-Ford algorithm, primarily designed for

graph processing, in particular, the amount of data needed for drawing a graph.

For routing, the fisheye approach tends to rely on the accuracy of routing tables. This

means that on nearest nodes, the routing information will be much more accurate than

for far nodes. This accuracy is represented by the amount of information exchanged

and the time interval they are exchanged over.

3.2.1.4 Hierarchical State Routing (HSR)

HSR is a proactive routing protocol introducing a notion of hierarchy. It uses dynamic

groups, hierarchic levels with an efficient management of localisation. With HSR, the

topology of the network is saved on a hierarchic basis, and, the network is split into

subsets, or groups. In each group, a node must be elected for representing other nodes.

This representative node will be part of the higher level group, and then, must elect

again another representative.

The routing decision is taken using nodes’ addresses. The address scheme must be also

hierarchic, following the same tree as the topology.


3.2.1.5 Distance Routing Effect Algorithm for Mobility

(DREAM)

DREAM is based on the localisation of mobile nodes, and introduces a notion of

geography. Each node knows approximately its localisation in the topology. When data

has to be sent, and the sender knows approximately the localisation of the destination,

it broadcasts the packet in the destination direction. Otherwise, the packet is simply

broadcast on the whole topology. In order to localise properly each node in the

network, “TOPOLOGY CONTROL” packets with localisation information are

broadcasted regularly.

3.2.2Reactive Protocols

As covered in chapter 3.2.1, proactive protocols define a best path through the

topology for every available node. This route is saved even if not used. Permanently

saving routes cause a high traffic control on the topology, in particular in networks

with a high number of nodes.

Reactive protocols are the most advanced design proposed for routing on Ad Hoc

networks. They define and maintain routes depending on needs. There are different

approaches for that, but most are using a backward learning mechanism or a source

routing mechanism.

3.2.2.1Ad hoc On-demand Distance Vector (AODV)

AODV was proposed to standardisation by the RFC 3561 in July 2003. It was designed

by the same people who designed DSDV. AODV is a distance vector routing protocol,

which means routing decisions will be taken depending on the number of hops to

destination.

A particularity of this network is to support both multicast and unicast routing.

3.2.2.1.1Algorithm

The AODV algorithm is inspired from the Bellman-Ford algorithm like DSDV. The

principal change is to be On Demand. The node will be silent while it does not have

data to send. Then, if the upper layer is requesting a route for a packet, a “ROUTE


REQUEST” packet will be sent to the direct neighbourhood. If a neighbour has a route

corresponding to the request, a packet “ROUTE REPLY” will be returned. This packet

is like a “use me” answer. Otherwise, each neighbour will forward the “ROUTE

REQUEST” to their own neighbourhood, except for the originator and increment the

hop value in the packet data. They also use this packet for building a reverse route

entry (to the originator). This process occurs until a route has been found.

Another part of this algorithm is the route maintenance. While a neighbour is no longer

available, if it was a hop for a route, this route is not valid anymore. AODV uses

“HELLO” packets on a regular basis to check if they are active neighbours. Active

neighbours are the ones used during a previous route discovery process. If there is no

response to the “HELLO” packet sent to a node, then, the originator deletes all

associated routes in its routing table. “HELLO” packets are similar to ping requests.

While transmitting, if a link is broken (a station did not receive acknowledgment from

the layer 2), a “ROUTE ERROR” packet is unicast to all previous forwarders and to

the sender of the packet.

3.2.2.1.2Illustration

Figure 7: Example of AODV route discovery


In the example illustrated by figure 7, A needs to send a packet to I. A “ROUTE

REQUEST” packet will be generated and sent to B and D (a). B and D add A in their

routing table, as a reverse route, and forward the “ROUTE REQUEST” packet to their

neighbours (b). B and D ignored the packet they exchanged each others (as duplicates).

The forwarding process continues while no route is known (c).

Once that receives the “ROUTE REQUEST” from G (d), it generates the “ROUTE

REPLY” packet and sends it to the node it received from. Duplicate packets continue to

be ignored while the “ROUTE REPLY” packet goes on the shortest way to A, using

previously established reverse routes (e and f).

The reverse routes created by the other nodes that have not been used for the “ROUTE

REPLY” are deleted after a delay. G and D will add the route to I once they receive the

“ROUTE REPLY” packet.

3.2.2.2Dynamic Source Routing (DSR)

As a reactive protocol, DSR has some similitude with AODV. Thus, the difference with

AODV is that DSR focuses on the source routing rather than on exchanging tables [7].

3.2.2.3Temporally-Ordered Routing Algorithm (TORA)

This protocol has been made for reducing the impact of mobility in Ad Hoc networks.

For reducing this impact, each node is learning more than one route for each

destination. By this way, if links are broken, the impact is minimal, only a few routes

will be broken. Another characteristic of this protocol is that control messages are only

concerned with nodes near the event source of these messages. For example, if a link is

broken, the broadcast concerning this event will not be relayed on the whole topology.

In this protocol, using the shortest path is not the most important, as using the longest

path avoids traffic and latency related to the route discovery process.

TORA also uses Directed Acyclic Graph (DAG), using the direction of the node for the

broadcasting process.


3.2.2.4Relative Distance Micro-discovery Ad Hoc Routing

(RDMAR)

RDMAR has been made in order to reduce the amount of control traffic caused by

quick topology changes. This protocol uses a new way to discover routes, called

Relative Distance Micro-discover (RDM). The idea of RDM is to rely on the fact that

broadcast messages can be based on a relative distance (RD) between two nodes. An

algorithm is used for estimating the distance between two nodes, using information

about node mobility, time past between the last communication and the last value of

the RD. Based on this new RD, flooding can be made only in the direction where the

node might be found.

3.2.3Hybrids Protocols

A routing protocol is proactive when it continually maintains its routing table. By this

way, routes are available when needed. Reactive protocol starts a route discovery

process when data has to be sent. The advantage of a proactive protocol is that when a

datagram must be sent, the route is already available, so, the processing time to find a

route in the routing table is not important. Reactive protocols require much more time

for finding a route as they are “On Demand”. But, in an Ad Hoc environment, nodes

are willing to move, and then, it reflects frequent changes in the topology. In such an

environment, reactive protocols are much more reliable and efficient as proactive

protocol will require exchanging a lot of data.

Hybrid protocols tend to merge advantages of reactive and proactive protocols. Their

aim is to use an “On Demand” route discovery system, but, with a limited research

cost.


Chapter 4WOSPF

This chapter describes the extensions to OSPFv2 [4] needed to support mobile ad hoc

networking. The extensions are based on the ideas proposed in Cisco’s Internet-draft

[8] proposing a MANET extension to OSPFv3. Throughout this thesis, the term

“Cisco’s draft” will refer to [8]. Before describes the WOSPF, I Make some important

details to understand the OSPF protocol.

4.1Open Shortest Path First (OSPF)

OSPF is a very comprehensive and complex routing protocol, and has implemented

several extensions to adapt to different network types. This section describes a selected

OSPF relevant to the wireless extensions described in this chapter. Which is OSPFv2

(described in RFC 2328).

4.1.1 Overview

OSPF is a link-state (LS) routing protocol. Each router running OSPF maintains a

database describing the Autonomous System's (AS) topology. The database is referred

to as the Link-State database (LS-database). All routers run the same algorithm in

parallel. From the LS-database each router constructs a tree of shortest path to the rest

of the network with itself as a root. Each router distributes its local state throughout the

AS by flooding. OSPF routes IP packets based solely on the destination IP address;

they are routed "as-is", then, they are not encapsulated in any further protocol headers.

When several equal-cost routes to a destination exist, traffic is distributed equally

among them. The cost of a route is described by a simple dimensionless metric. OSPF

allows sets of networks to be grouped together on areas. The topology of an area is

hidden from the rest of the AS. All OSPF protocol exchanges are authenticated.

Externally derived routing data is advertised throughout the AS.Two routers that have

interfaces to a common network are called neighboring routers. These routers form

relationships between them called adjacencies. The adjacencies are formed to exchange

routing information.The unit of information describing the local state of a router is


called a Link-State Advertisement (LSA). These advertisements are flooded throughout

the routing domain. The flooding is done using the Hello protocol.Each network that

has at least two routers has a Designated Router (DR) that is elected by the Hello

protocol. This router enables a reduction in the number of adjacencies required to run

OSPF.

4.1.2 OSPF Functional Summary A separate copy of OSPF's routing

algorithm runs in each area. Routers having interfaces to multiple areas run multiple

copies of the algorithm. Routing algorithm is as follows:

• Intra-Area RoutingWhen a router starts, it first initializes the routing

protocol data structure. Then, it waits for indication from the lower-level

protocols that its interfaces are functional. Being the interfaces functional,

the router sends Hello packets to its neighbors, and in turn receives Hello

packets. The router will attempt to form adjacencies with some of it’s newly

acquired neighbors. LS-databases are synchronized between pairs of

adjacent routers. The Designated Router (DR) determines which routers

should become adjacent. Adjacencies control the distribution of routing

information; routing updates are sent and received only on adjacencies. A

router periodically advertises its link-state. Link-state is also advertised

when a router's state changes. Router's adjacencies are reflected in its Link-

State Advertisements (LSAs). The relationship between adjacencies and

link-state allows the protocol to detect dead routers in a timely fashion.

LSAs are flooded throughout the area. The flooding algorithm ensures that

all routers in an area have the same LS-database. The database consists of

the collection of LSAs originated by routers belonging to the area. From

this database, each router calculates a shortest-path tree with itself as root.

From this tree a routing table is built for the protocol.

• Inter-Area RoutingIn order to be able to route to destinations outside of

the area, the area border routers (ABRs) inject additional routing

information into the area. This information is a distillation of the rest of the

AS's topology. Each ABR is connected to the backbone; each of them

summarizes the topology of its attached non-backbone areas for


transmission on the backbone and hence to all other ABRs. Each ABR then

has complete topological information concerning the backbone and the area

summaries from each of the other ABRs. From this information the router

calculates paths to all inter-area destinations. The router then advertises

these paths into its attached areas. This enables the internal routers to pick

the best exit route when forwarding to inter-area destinations.

• AS external routesRouters that have information regarding other ASs

can flood this information throughout the AS. This information is

distributed verbatim to every router, except for those belonging to stub

areas.

4.1.3 OSPF Standard Header

OSPF runs directly over IP. All OSPF packets share a common protocol header. Every

OSPF packet starts with a standard 24 byte header. This header contains all the

information necessary to determine whether the packet should be accepted for further

processing.

Version #: The version number of the protocol.

Packet Type

The OSPF packet types are one of this as follow:


Type Packet name Protocol function

1 Hello Discover/maintain neighbors

2 Database Description Summarize database contents

3 Link State Request Database download

4 Link State Update Database update

5 Link State Ack Flooding acknowledgment

Packet Length: Total length, including the standard header.Router ID: Router

identification of the packet's originator.Area ID: The OSPF area that the packet is

being sent into.Checksum: Standard IP 16-bit one's complement checksum of the entire

packet, excluding the 64-bit authentication field.AuType and Authentication: AuType

indicates the type of authentication procedure in use. The 64-bit field is then used by

the chosen authentication procedure.

4.2WOSPF OverviewDeploying a legacy routing protocol defined for wired networks in an OSPF-MANET

calls for modifications and optimizations. First of all, non-MANET routing protocols

are not designed for operation in a multi-hop environment. Second, dissemination of

routing packets in a network whose topology is rapidly changing requires intelligent

and optimized techniques, unless resource consuming, pure flooding is to be used.

OSPF-MANET interfaces should take into account the different aspects of resource

constrained OSPF-MANET environments; the bandwidth may be scarce, topology is

unpredictable, and link quality poor. The wireless extensions described in this chapter

aim to define an interface that can cope with these properties.

4.2.1 OSPF Extensions

Since the winter of 2005 a working group, referred to as the OSPF MANET design

team, within the IETF have been focusing on two active Internet drafts. One of these is

Cisco’s draft [8]. The other (and competitive) draft is a draft published by Boeing [10].

The approach proposed in [10] is often referred to as OSPF MANET Designated


Router (OSPFMDR), while the approach proposed in Cisco’s draft is referred to as

Overlapping Relays.

• Wireless OSPF-OR

This draft comes from Cisco’s draft, elects a source dependent set of

routers that are to relay routing packets. It is close connection with OLSR.

• Wireless OSPF-MDR

Elects a source independent set3 of routers that are to relay routing packets

extends the OSPFv3 Hello packet to carry such information

4.2.2 WOSPF-OR

One of the most deployed flooding optimizations used in OSPF networks today, the

DR mechanism, will not perform correctly in OSPF-MANETs. This is because OSPF-

MANETs are not true multi-access networks, as is a DR assumption, in OSPF-

MANETs, two nodes on the same network segment cannot be assumed to have two-

way connectivity. Therefore, the [3] adopt the ideas behind the OLSR optimized

flooding scheme MPR Relays, and implement the overlapping relays mechanism.

Figure 8 depicts a very simple scenario, consisting of only four nodes. It is assumed

that the leftmost node is the originator of the packet, although the flooding would be

exactly the same for either of the nodes. As the figure shows, every node (except the

packet originator) retransmits the packet. Hence, we have n − 1 retransmissions. This

scheme is not optimal, as many duplicate packet received are the result of an

unnecessary transmission. This scheme could benefit from some flooding

modifications designed especially for OSPF-MANETs as in figure 9.


Figure 8: flooding in a wireless network

Figure 9: Wireless network with an optimized flooding scheme.

4.2.3 Active Overlapping Relay (AOR)

The AOR is method used in WOSPF-OR that deals with wireless OSPF MANET

routing protocol, the algorithm which that used on AOR is as follow:

1. Select all neighbors which have one hop from originator.

2. On each neighbor compute the number of the one hop.

3. Remove the ones neighbor which is already exist on originated.

4. Select the node with the highest number of neighbor as an AOR, after that

recomputed the number of neighbors of the originated.

5. Return step 4 until create own network.

As we see in figure below, in this situation before calculating and manipulating the

AOR. In figure, the OR selected an AOR set which that can be forward data from

originator to the next hop.


Figure 10: before and after implement AOR

4.2.4 Flooding in WOSPF-OR and

OLSR

As MANETs typically consist of resource constraint nodes communicating over low

capacity wireless links, some sort of flooding optimization would clearly be beneficial.

The flooding scheme used in WOSPF-OR is essentially the same as the use of MPRs in

the OLSR protocol.

Chapter 5Implementation


In this chapter we discuss our implementation. I used some of tools that help me to

reach at my goals. The main software I used with along of my project is The Network

Simulator NS-2, Network Animator NAM, XGRAPH, TCL & C++ programming,

kivio and Linux OS. I made some evaluation between different ad hoc routing

protocols, since the WOSPF-OR It is close connection with OLSR I am used OLSR

rather than WOSPF-OR.

5.1Network Simulator (NS2)

NS is a discrete event simulator targeted at networking research provided by USC/ISI

[NS2]. It is open source which allows to modification. It models system as events,

which the simulator has, list of the process is made such way: “take next one, run it,

until done”. Each event happens in an instant of virtual (simulated) time, but takes an

arbitrary amount of real time. The design of the simulator is separating the “data” from

the control: C++ for “data” (per packet processing, core of ns, fast to run, detailed,

complete control); and OTCL for control (simulation scenario configurations, periodic

or triggered action, manipulating existing C++ objects, fast to write and change).

Figure 11: description of NS-2 (merge between C++ and OTCL)

“NS” Components are Ns the simulator it self and Nam the network animator that

permits to visualize ns output and that provides a GUI interface to generate ns scripts.

For the wireless part, NS provides ad hoc routing and mobile IP. NS provides also

traffic and topology generators and simple trace analysis.


For running a simulation using NS2, the first thing to do is describe the scenario to

simulate using a TCL script. Then, NS2 will compute the simulation and produce a

trace file of events happened. This trace file contains data about packets sent, received,

forwarded, dropped, size of packets, type of packets, and It also contains nodes moved

logs. [6]

5.2Simulation Scenario and results

The scenarios for simulation must demonstrate efficiency of protocols depending on

Ad Hoc specifications. I used the sixth different scenarios and implemented in each our

routing protocol that we considered before (OLSR, AODV, and DSDV). The

evaluations metric which I am supposed are as follow:

• Packet receives and packet lost.

• CPU utilization.

• Traffic engineering.

5.2.1First Scenario:

Number of nodes: 6 nodes.

Mobility: no.

Topology: 800m * 800m.

Time of simulation: 120s (2minutes).


Figure 12: packets received and packet lost.

Figure 13: CPU utilization Figure 14: Traffic engineering

Result:

As we saw in figure 12 the AODV routing protocol gives us the best result

regarding packets received and good result regarding lost packets. On the other hand

side, the DSDV routing protocol gives us the best result regarding packets lost and not

enough result regarding received packets. Then, in figure 13 the OLSR routing

protocol gives us the best result regarding CPU utilization. Finally, The AODV in

figure 14 gives us the best result regarding traffic engineering


Regarding this scenario we conclude the best protocol is AODV routing protocol.

5.2.2Second Scenario:


Mobility: only one node that have mobility.



Figure 15 :packets received and packet lost.



Result:

As we saw in figure 15 the OLSR routing protocol gives us the best result

regarding packets received and the best result regarding lost packets. On the other hand

side, the AODV routing protocol gives us good result regarding packets received but

not good result regarding packets lost. Then, in figure 16 the DSDV routing protocol

gives us the best result regarding CPU utilization. Finally, The AODV in figure 17

gives us the best result regarding traffic engineering

Regarding this scenario we conclude the best protocol is OLSR routing protocol.

5.2.3Third Scenario:


Mobility: yes, with random mobility.

Node speed: randomly change between 0-20m/s with 2s pause time






Result:

As we saw in figure 18 the DSDV routing protocol gives us the best result

regarding packets received and good result regarding lost packets. On the other hand

side, the OLSR routing protocol gives us good result regarding packets received and

the best result regarding packets lost. Then, in figure 19 the OSLR routing protocol

gives us the best result regarding CPU utilization. Finally, The DSDV in figure 20

gives us the best result regarding traffic engineering.

Regarding this scenario we conclude the best protocol is DSDV routing protocol.

5.2.4Fourth Scenario:


Mobility: no.






Result:

As we saw in figure 21 the AODV routing protocol gives us the best result

regarding packets received and bad result regarding lost packets. On the other hand

side, the OLSR routing protocol gives us the best result regarding packets lost. Then, in

figure 22 the DSDV routing protocol gives us the best result regarding CPU utilization.

Finally, The DSDV in figure 23 gives us the best result regarding traffic engineering.



5.2.5Fifth Scenario:


Mobility: only one node which is received data that have mobility.






Result:

As we saw in figure 24 the DSDV routing protocol gives us the best result

regarding packets received and the best result regarding lost packets. On the other hand

side, the AODV routing protocol gives us good result regarding packets received and

good result regarding packets lost. Then, in figure 25 the DSDV routing protocol gives

us the best result regarding CPU utilization. Finally, The AODV in figure 26 gives us

the best result regarding traffic engineering.


5.2.6Sixth Scenario:


Mobility: yes, with random mobility.

Node speed: randomly change between 0-20m/s with 2s pause time





Figure 28-a: CPU utilization Figure 29-b: Traffic engineering

Result:

As we saw in figure 27 all routing protocols gives us the worst result regarding

packets received and packets lost, in this situation the AODV routing protocol gives us

best result regarding packets received relatively the others protocols. Then, in figure

28-a the AODV routing protocol gives us the best result regarding CPU utilization.

Finally, the DSDV in figure 28-b gives us the best result regarding traffic engineering.

Regarding this scenario we conclude the best protocol is AODV routing protocol.


5.2.7Scenario Visualization


Figure 30: scenario of 6 nodes send from node 0 to5.

Figure 31: scenario of 30 nodes send from node 0 to 5.


Figure 32: scenario of 30 nodes randomly motion.


Chapter 6Conclusion and Future Works

This chapter concludes this final project. We discovered during this project the

problems associated with Ad Hoc networks, more specifically routing on Ad Hoc

networks. We also discovered some of solutions for these problems. Then, we

discovered in more details the OSPF and WOSPF and conclude it by similarities with

OLSR. After that, we make six different scenarios and applied over three protocols,

which are “OLSR”, “AODV”, and “DSDV” to evaluate performance. We saw in the

first scenario of 6 fixed nodes the AODV is the best choice. In the second scenario 6

nodes only the receiving nodes have mobility in the topology, the OLSR is the best

choice. In the third scenario 6 nodes with random motion in the topology, the DSDV is

the best choice. In the fourth scenario 30 fixed nodes, the DSDV is the best choice. In

the fifth scenario 30 nodes only the receiving nodes have mobility in the topology, the

DSDV is the best choice. In the sixth scenario 30 nodes with random motion in the

topology, the AODV is the best choice. Even by testing these three protocols, there is

no perfect solution to make decision that an X protocol is the best. It is dependent on

the context. So we suggest that you use the NS simulator as a tool for choosing the

most adequate ad hoc routing protocol for your wireless ad hoc network before

implementing it.

At the end of this project, we get a lot information and knowledge such as:

• Simulation

1. Perform NS simulation

2. Wireless OTCL scripts

3. Extension to the NS simulator

4. Ability to add contributed modules to NS even with different versions

(which required some modification to some NS source code).

5. Ability to implement a new protocol in NS (in both parts C++ and

OTCL).

• Networking


1. I had learned OSPF which is the most complex Internet protocol.

2. I had learned MANET routing protocol.


References:

[1]http://www.ece.clemson.edu/commnet/import.htm

[2] Mathieu Gallissot “Routing on Ad Hoc Networks” may 2007.

[3] Kenneth Holter, Wireless Extensions to OSPF, Master thesis, 2nd May 2006.[4]RFC 2328 : OSPF Version 2[5]Humayun Bakht, “Problems in MANET” presentation.[6]Henrik Christiansen, ” Simulator requirements“ , sep 2003[7]David A. Maltz, On-Demand Routing in Multi-hop Wireless Mobile Ad Hoc

Networks, Doctor of Philosophy thesis, May 2001[8]M. Chandra, Extensions to OSPF to Support Mobile Ad Hoc Networking,

IETF, April 2005.[9] A. Roy, .Adjacency Reduction in OSPF using SPT Reachability,.Internet-Draft

(work in progress) draft-roy-ospf-smart-peering-01, IETF, November 2005.[10]R. Ogier and P. Spagnolo, .MANET Extension of OSPF using CDS Flooding,.

Internet-Draft (work in progress) draft-ogier-manet-ospfextension- 07, IETF, March 2006.

[11]http://en.wikipedia.org [12]Philippe Jacquet, OLSR for MANET, INRIA.


http://en.wikipedia.org/

List of symbols and/or abbreviations

GSM: Global System for Mobile Communications

IETF: Internet Engineering Task Force

MANET: Mobile Ad hoc NETworks

RFC: Request for Comments

INRIA : French National Institute for Research in Computer Science and

Automatic Control

OSPF : Open Shortest Path First.

WOSPF : Wireless Open Shortest Path First.

DSDV : Destination Sequenced Distance Vector.

OLSR : Optimized Linked State Routing

FSR : Fisheye State Routing

HSR : Hierarchical State Routing

DREAM : Distance Routing Effect Algorithm for Mobility

AODV : Ad hoc On-demand Distance Vector

DSR : Dynamic Source Routing

TORA : Temporally-Ordered Routing Algorithm

RDMAR : Relative Distance Micro-discovery Ad Hoc Routing

ZRP : Zone Routing Protocol

HSLS : Hazy Sighted Link State Routing Protocol

NS-2 : Network Simulator

NAM : Network Animator


4168945 evaluation of the wireless ospf routing protocol

Documents

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