Transcript Slide 1

Performance Analysis of AODV and
SAODV Routing Protocols in Ad-Hoc Mesh
NetworksA Simulation Study
Sangeeta Ghangam
Division of Computing Studies, Arizona State University
July 30, 2007
Advisor: 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 applications
Disaster recovery, Intelligent transportation systems
• Examples:
MIT’s RoofNet- An experimental WMN
Tempe, 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 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)
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.dimgt.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 = seed
Send:
Type, Length Hash- function, Max-hop-count, Tophash&
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)
Network Model for Comparisons in
OPNET
Server
IP backbone
Gateway1
R
BSS1
Gateway2
R
BSS2
R
BSS3
R
BSS4
Simulation Parameters
Parameters
Values
Room Size
Mobile Nodes
4000m x 4000m
2 in each BSS
Random Waypoint
Speed - 2m/s to 7 m/s
Start: Uniform( 0, 100)s
Pause: Uniform(50, 100)s
Wired Links: 100 Base T
Wireless Links: IEEE 802.11g @ 11Mbps
Wired Links: OSPF
Wireless Links: AODV/SAODV
Bursty
Uniform(100,110)s
Poisson (9000)
Poisson (4000)
Poisson (8000)
Poisson (80)
200 minutes
Throughput (bits/sec)
Route discovery time(sec)
Delay (sec)
Routing traffic sent ( bits/sec)
Routing traffic received ( bits/sec)
Load (bits/sec)
Mobility
Mac Layer
Routing Protocols
Application Traffic
Start
End
Request
Response
Request/hr
Simulation Time
Metrics
Throughput & Delay
SAODV
AODV
Time
Delay (sec)
Throughput (bits/sec)
SAODV
AODV
Time
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
Load (bits/sec)
AODV
Time
Route discovery time (sec)
SAODV
AODV
SAODV
Time
SAODV and AODV have comparable route discovery time.
SAODV though imposes a higher load on the network than AODV.
SAODV
AODV
Time
Routing Traffic Sent (bits/sec)
Routing Traffic Received (bits/sec)
Routing Traffic Received & Sent
SAODV
AODV
Time
SAODV is bandwidth intensive compared to AODV as it has a higher amount of
control traffic.
Scalability of AODV and SAODV
AODV
SAODV
30 nodes
Route Discovery Time (/sec)
Route Discovery Time (/sec)
50 nodes
50 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.
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.