Performance Analysis of AODV and SAODV Routing Protocols in Ad-Hoc Mesh

Networks- A Simulation Study

Sangeeta GhangamSangeeta GhangamDivision of Computing Studies, Arizona State UniversityDivision of Computing Studies, Arizona State University

July 30, 2007July 30, 2007Advisor: Prof. Bruce MillardAdvisor: Prof. Bruce Millard

Introduction to Mesh Networks• Wireless Mesh Networks(WMNs) have a 3-tier

architecture where different protocols work in tandem

• Infrastructure, client and hybrid WMN’s• WMN’s have several applications

Metro area coverage, Military applicationsDisaster recovery, Intelligent transportation systems

• Examples:MIT’s RoofNet- An experimental WMNTempe, Gilbert, Chandler, and Philadelphia – city

WMN

Wireless Mesh Network

A Survey of Wireless Mesh Networks, IEEE Radio Communications, pp S23—S30, Sept 2005

WMN’s & Mobile Ad-hoc Networks (MANET’s)

• WMN’s diversify the capabilities of MANET’s• IEEE 802.11’s Extend Service Set (ESS) mesh

networking task group is working on a routing protocol for WMN based on AODV(Ad-hoc On demand Distance Vector)

• BelAir, Tropos, Strix Systems, Cisco etc. have WMN products using routing protocols based on AODV

Why AODV?• A reactive protocol which

finds routes on demand• Low overhead and adjusts

to dynamic environment• Provides loop free routes

with the use of sequence #’s

• Has both unicasting & multicasting capability

• Works in 3 modes Route discovery Route maintenance Local connectivity

management

Reverse Path Setup Forward Path Setup

C.E.Perkins, E.M.Royer, “Ad-hoc On-Demand Distance Vector Routing”, Proc. of ACM, 2002

AODV

• AODV works in a implicit ‘trust your neighbor’ mode

• Two main security requirementsNode AuthenticationMessage Integrity

• Secure AODV (SAODV) adds an extension to different AODV packet formats to incorporate digital signature for protecting the non-mutable information and hash chains to protect the mutable information(hop count)

OPNET: The Simulation Environment

• Provides an OOP approach to network design

• Has a hierarchical modeling architecture similar to the structure of communication networks

• Provides ease of use via a GUI or the flexibility to create custom models via programming interface

• Integrated post simulation analysis tools

Designing the SAODV Model• SAODV model in OPNET follows from

the pre-existing AODV model• Implements the hash chain

functionality• New data structures for packet

formats• New functions to implement the

revised packet creation, memory allocation & de-allocation etc. has been created

• A cryptoSys API toolkit, which implements a random number generator & MD5 hash algorithm, from DiManagement services (http://www.di-mgt.com.au/crypto.html) is use

The Hash Chain Mechanism Creation(RREQ (Route REQuest)and RREP(Route

REPly)):Set Max-hop-count = TTL (time to live)

Generate a Random Number ( seed) Calculate Top-hash = h max _hop_count ( seed) Set Hash = seedSend:

Type, Length Hash- function, Max-hop-count, Top-hash& Hash fields with the original AODV RREQ and RREPVerification:

Top_hash== h (max_hop_count – hop_count) (Hash)Account for the additional hop h( Hash)

Network Model for Comparisons in OPNET

Server

IP backbone

Gateway1 Gateway2

RRRR

BSS4BSS3BSS1 BSS2

Simulation ParametersParameters Values

Room Size 4000m x 4000mMobile Nodes 2 in each BSS

Mobility

Random WaypointSpeed - 2m/s to 7 m/s

Start: Uniform( 0, 100)sPause: Uniform(50, 100)s

Mac Layer Wired Links: 100 Base TWireless Links: IEEE 802.11g @ 11Mbps

Routing Protocols Wired Links: OSPFWireless Links: AODV/SAODV

Application TrafficStartEnd

RequestResponse

Request/hr

BurstyUniform(100,110)s

Poisson (9000)Poisson (4000)Poisson (8000)Poisson (80)

Simulation Time 200 minutes

Metrics

Throughput (bits/sec)Route discovery time(sec)

Delay (sec)Routing traffic sent ( bits/sec)

Routing traffic received ( bits/sec)Load (bits/sec)

Throughput & DelayTh

roug

hput

(bits

/sec

)

Del

ay (s

ec)

Time Time

SAODVSAODV

AODVAODV

SAODVSAODV

AODVAODV

SAODV has a higher delay and throughput for a similar sized network even with less number of nodes creating application traffic.

Load & Route Discovery Time

Time

Load

(bits

/sec

)

Rout

e di

scov

ery

time

(sec

)

Time

SAODVSAODV

AODVAODVSAODVSAODV

AODVAODV

SAODV and AODV have comparable route discovery time.SAODV though imposes a higher load on the network than AODV.

Routing Traffic Received & Sent

Time Time

Routi

ng T

raffi

c Re

ceiv

ed (

bits

/sec

)

Routi

ng T

raffi

c Se

nt (

bits

/sec

)

SAODVSAODV

AODVAODV

SAODVSAODV

AODVAODV

SAODV is bandwidth intensive compared to AODV as it has a higher amount of control traffic.

Scalability of AODV and SAODV

Time

Rout

e D

isco

very

Tim

e (/

sec)

Time

Rout

e D

isco

very

Tim

e (/

sec)

50 nodes

30 nodes15 nodes

50 nodes

30 nodes15 nodes

AODVAODV SAODVSAODV

The Route Discovery time more than doubles, as the number of nodes increases for AODV and SAODV.

Summary & ConclusionsSummary: SAODV model created in OPNET and compared against the

existing AODV model. Different sized networks designed for comparing and

analyzing the protocols.Conclusions: Both SAODV and AODV show comparable results up to a

mid-sized network of about 30 nodes with some mobile nodes.

AODV performs well over different network architectures and is well suited for mesh networks.

SAODV only works well in a single tier and hence cannot be used without modifications for mesh networks.