1. Performance Analysis of AODV and SAODV Routing Protocols in Ad-Hoc Mesh Networks- A Simulation Study
Sangeeta Ghangam
Division of Computing Studies, Arizona State University
July 30, 2007
Advisor: Prof. Bruce Millard 1

2. 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 applications
Disaster recovery, Intelligent transportation systems
Examples:
MIT’s RoofNet- An experimental WMN
Tempe, Gilbert, Chandler, and Philadelphia – city WMN 2

3. Wireless Mesh Network
A Survey of Wireless Mesh Networks, IEEE Radio Communications, pp S23—S30, Sept 2005 3

4. WMN’s & Mobile Ad-hoc Networks (MANET’s)
WMN’s diversify the capabilities of MANET’s
IEEE ’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 4

5. 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 5

6. AODV AODV works in a implicit ‘trust your neighbor’ mode
Two main security requirements
Node Authentication
Message 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) 6

7. 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 7

8. 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 ( is use 8

9. 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 = seed
Send:
Type, Length Hash- function, Max-hop-count, Top-hash& Hash fields with the original AODV RREQ and RREP
Verification:
Top_hash== h (max_hop_count – hop_count) (Hash)
Account for the additional hop h( Hash) 9

10. Network Model for Comparisons in OPNET
Server
IP backbone
Gateway1
Gateway2 R R R R
BSS1
BSS2
BSS3
BSS4 10

11. Simulation Parameters
Values
Room Size
4000m x 4000m
Mobile Nodes
2 in each BSS
Mobility
Random Waypoint Speed - 2m/s to 7 m/s Start: Uniform( 0, 100)s Pause: Uniform(50, 100)s
Mac Layer
Wired Links: 100 Base T Wireless Links: IEEE 11Mbps
Routing Protocols
Wired Links: OSPF Wireless Links: AODV/SAODV
Application Traffic Start End Request Response Request/hr
Bursty Uniform(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) 11

12. Throughput (bits/sec)
Throughput & Delay
SAODV
SAODV
Throughput (bits/sec)
AODV
AODV
Delay (sec)
Time
Time
SAODV has a higher delay and throughput for a similar sized network even with less number of nodes creating application traffic. 12

13. Load & Route Discovery Time
SAODV
AODV
AODV
SAODV
Route discovery time (sec)
Load (bits/sec)
Time
Time
SAODV and AODV have comparable route discovery time.
SAODV though imposes a higher load on the network than AODV. 13

14. Routing Traffic Received (bits/sec) Routing Traffic Sent (bits/sec)
Routing Traffic Received & Sent
SAODV
SAODV
AODV
Routing Traffic Received (bits/sec)
AODV
Routing Traffic Sent (bits/sec)
Time
Time
SAODV is bandwidth intensive compared to AODV as it has a higher amount of control traffic. 14

15. Route Discovery Time (/sec) Route Discovery Time (/sec)
Scalability of AODV and SAODV
AODV
SAODV
50 nodes
50 nodes
Route Discovery Time (/sec)
Route Discovery Time (/sec)
30 nodes
15 nodes
30 nodes
15 nodes
Time
Time
The Route Discovery time more than doubles, as the number of nodes increases for AODV and SAODV. 15

16. Summary & Conclusions Summary:
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. 16