This document compares the performance of two routing protocols for mobile ad hoc networks: Destination Sequenced Distance Vector (DSDV) and Ad Hoc On-Demand Distance Vector (AODV). It presents the results of simulations run using the ns-2 network simulator. The simulations varied the number of nodes, pause time (mobility rate), and number of data sources. The performance metrics measured were packet delivery ratio, average end-to-end delay, and normalized routing load. The results showed that AODV had higher packet delivery ratios and lower routing loads than DSDV. However, AODV experienced higher delays than DSDV due to its on-demand route discovery process. DSDV performed better in low

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International Conference on Advanced Communication Systems, January 10 - 12, 2007, GCT, Coimbatore. ICACS - 2007
Performance Comparison of AODV and DSDV Routing Protocols for Ad-hoc
Wireless Networks
1
Narendra Singh Yadav 2
Dr. R.P.Yadav
1 Department of ECE, The Malaviya National Institute of Technology, Jaipur
Email: narensinghyadav@yahoo.com
2 Department of ECE, The Malaviya National Institute of Technology, Jaipur
Email : rpyadav@mnit.ac.in
ABSTRACT
An ad hoc network is a collection of mobile nodes
communicating through wireless channels without any existing
network infrastructure or centralized administration. Because of
the limited transmission range of wireless network interfaces,
multiple “hops” may be needed to exchange data across the
network. Consequently, many routing algorithms have come into
existence to satisfy the needs of communications in such networks.
This paper presents performance comparison of the three routing
protocols AODV and DSDV. Protocols were simulated using the
ns-2 and were compared in terms of packet delivery fraction,
normalized routing load and average delay, while varying number
of nodes, and pause time. Simulation revealed that although DSDV
perfectly scales to small networks with low node speeds, AODV is
preferred due to its more efficient use of bandwidth.
Keywords:
Ad-Hoc Wireless Networks, AODV, DSDV, Ns-2
I.INTRODUCTION
Advances in computer and telecommunication
industries have made wireless networks increasingly popular.
Basically, there are two types of systems for wireless networks.
One is the base-station (BS) oriented that is cellular (one hop)
networks [1]. In BS- oriented wireless networks the mobile hosts
communicate with base station. The presence of BS simplifies
routing and resource management as the routing decisions are made
in a centralized manner with more information about the destination
node. The BS- oriented wireless network has better performance
and is more reliable
The other is the ad hoc (multihop) wireless networks
[2]. Ad hoc wireless networks (formerly called packet radio
networks) are defined as mobile distributed multihop wireless
networks. In ad hoc wireless networks there is no predetermined
topology (pre existing fixed infrastructure) and no central control.
The nodes in ad hoc communicate without wired connections
among themselves by creating a network “on the fly”. The absence
of any central control makes the routing a complex.Ad hoc wireless
network topology is more desirable because of its low cost, ease
and speed of deployment and flexibility.
Routing is a core problem in networks for delivering
data from one node to another. Ad hoc wireless networks have
special limitations and properties [3]. Therefore, routing protocols
for wired networks cannot be directly used in ad hoc wireless
networks; routing protocols for ad hoc wireless networks need to
be designed and implemented separately.
Routing protocols for ad hoc wireless networks can be
classified into two main categories: Proactive or table driven routing
protocols and Reactive or on-demand routing protocols.
To judge the merit of a routing protocol, one needs
metrics- both quantitative and qualitative- with which to measure
its suitability and performance [3]. These metrics should be
independent of any given routing protocol.
Dozens of routing protocols have been introduced [4],
all of which typically perform well in some situations while having
significant weaknesses in other cases. So the open problem lies in
that no one single routing algorithm/ protocol is suitable for
heterogeneity of ad hoc networks [3]. And this limitation could
not be solved without advanced computer and wireless
communication technology development specially hardware
evolution.
The paper is organized as follows: in Section II, a brief
description of routing protocols discussed in this work are
presented, in Section III the parameters of simulation and the
scenario are shown, in Section IV the simulation results are plotted
and argued, in Section V some conclusions are discussed.
II.DESCRIPTIONOFPROTOCOLS
Destination Sequenced Distance Vector (DSDV)
DSDV, an enhanced version of the distributed ellman-
Ford algorithm, belongs to the proactive or table driven family
where a correct route to any node in the network is always
maintained and updated [5].
In DSDV, each node maintains a routing table that
contains the shortest distance and the first node on the shortest
path to every other node in the network. A sequence number
created by the destination node tags each entry to prevent loops,
to counter the count –to-infinity problem and for faster
convergence.Thetablesareexchangedbetweenneighborsatregular
intervals to keep an up to date view of the network topology. The
tables are also forwarded if a node finds a significant change in
local topology. This exchange of table imposes a large overhead on
the whole network. To reduce this potential traffic, routing updates
are classified into two categories. The first is known as “full dump”
which includes all available routing information. This type of
updates should be used as infrequently as possible and only in the

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cases of complete topology change. In the cases of occasional
movements, smaller “incremental” updates are sent carrying only
information about changes since the last full dump. Each of these
updates should fit in a single Network Protocol Data Unit (NPDU),
and thus significantly decreasing the amount of traffic. Table
updates are initiated by a destination with a new sequence number
which is always greater than the previous one. Upon receiving an
updated table a node either updates its tables based on the received
information or holds it for some time to select the best metric
received from multiple versions of the same update from different
neighbors.
Ad hoc On-demand Distance Vector Routing (AODV)
AODV [6][7] is an improvement on the DSDV.AODV
uses an on- demand approach for finding routes. Since it is an on
- demand algorithm, a route is established only when it is required
by a source node for transmitting data packets and it maintains
these routes as long as they are needed by the sources.
AODV uses a destination sequence number, created by
the destination, to determine an up to date path to the destination.
A node updates its route information only if the destination
sequence number of the current received packet is greater than the
destination sequence number stored at the node. It indicates the
freshness of the route accepted by the source. To prevent multiple
broadcast of the same packet AODV uses broadcast identifier
number that ensure loop freedom since the intermediate nodes
only forward the first copy of the same packet and discard the
duplicate copies.
To find a path to the destination, the source broadcasts
a Route Request (RREQ) packet across the network. This RREQ
contains the source identifier, the destination identifier, the source
sequence number, the destination sequence number, the broadcast
identifier and the time to live field. Nodes that receives RREQ
either if they are the destination or if they have a fresh route to the
destination, can respond to the RREQ by unicasting a Route Reply
(RREP) back to the source node. Otherwise, the node rebroadcasts
the RREQ.
When a node forwards a RREQ packet to its neighbors,
it also records in its tables the node from which the first copy of
the request came. This information is used to construct the reverse
path for the RREP packet. AODV uses only symmetric links
because the route reply packet follows the reverse path of route
request packet. When a node receives a RREP packet, information
about the previous node from which the packet was received is
also stored in order to forward the data packets to this next node
as the next hop toward the destination. Once the source node
receives a RREP it can begin using the route to send data packets.
The source node rebroadcasts the RREQ if it does not
receive a RREP before the timer expires. It attempts discovery up
to some maximum number of attempts. If it does not discover a
route after this maximum number of attempts, the session is
aborted.
If the source moves then it can reinitiate route discovery
to the destination. If one of the intermediate nodes move then the
moved nodes neighbor realizes the link failure and sends a link
failure notification to its upstream neighbors and so on till it reaches
the source upon which the source can reinitiate route discovery if
needed.
III.SIMULATIONMODEL
For the purpose of a performance comparison detailed
performance simulations are performed for three main ad hoc
routing protocols i.e.AODV and DSDV. The simulations are done
using ns-2 [8].
The Distributed Coordination Function (DCF) of IEEE
802.11 for wireless LANs is used as the MAC layer protocol. An
unslotted carrier sense multiple access (CSMA) technique with
collision avoidance (CSMA/CA) is used to transmit the data
packets. The radio model uses characteristics similar to a
commercial radio interface, Lucent’s WaveLAN. WaveLAN is
modeled as a shared media radio with a nominal bit rate of 2 Mb/
s and a nominal radio range of 250m.
The protocols maintain a send buffer of 64 packets. It
contains all data packets waiting for a route, such as packets for
which route discovery has started, but no reply has arrived yet.
To prevent buffering of packets indefinitely, packets are dropped
if they wait in the send buffer for more than 30s.All packets (both
data and routing) sent by the routing layer are queued at the interface
queue until the MAC layer can transmit them. The interface queue
has a maximum size of 50 packets and is maintained as a priority
queue with two priori-ties each served in FIFO order. Routing
packets get higher priority than data packets.
Traffic Pattern
Continuous bit rate (CBR) traffic sources are used.
Only 512-byte data packets are used.All communication patterns
were peer-to-peer, and connections were started at times
uniformly distributed between 0 and 100 seconds. TCP sources
was avoided because TCP offers a conforming load to the
network, meaning that it changes the times at which it sends
packets based on its perception of the networks ability to carry
packets.
Traffic is generated using the following parameters:
Traffic Type : CBR
No of nodes : 50
No of sources: 15, 30, 45 sources
Rate: 4 packets per second for 15 and 30 sources, 3 packets per
sec for 45 sources
Movement Model
The node movement generator of ns-2 is used to
generate node movement scenarios. The parameters this
movement generator takes as input are number of nodes, pause
time, maximum speed, field configuration and simulation time.
The parameter, which is of primary importance, is pause time.
Pause time basically determines the mobility rate of the model,
as pause time increases the mobility rate decreases.
At the start of the simulations nodes are assigned some
random position within the specified field configuration, for pause

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time seconds nodes stay at that position and after that they make
a random movement to some other position. The movement speed
is uniformly distributed between 0 and maximum speed.
The following parameter values are used forgenerating
various mobility models:
Number of nodes: 50 nodes
Pause times: 0, 20, 40, 60, 80, 100 seconds
Maximum speed: 20 m/s
Field configuration: 500 X 500
Simulation time: 100 seconds.
Performance Metrics
The following performance metrics are evaluated:
•Packet delivery ratio The ratio of the data packets delivered to
the destinations to those generated by the CBR sources.
•Averageend-to-enddelay Thisincludesallpossibledelayscaused
by buffering during route discovery latency, queuing at the interface
queue, retransmission delays at the MAC, and propagation and
transfer times.
•Normalized routing load the number of routing packets
“transmitted” per data packet “delivered” at the destination
IV.PERFORMANCERESULTS
The simulation results are shown in the following
section in the form of line graphs. Graphs show comparison
between the two protocols by varying different numbers of
sources on the basis of the above-mentioned metrics as a function
of pause time.
Packet Delivery Fraction
Figure 1 show a comparison between both the routing protocols
on the basis of packet delivery fraction using a different number of
traffic sources.
Packet delivery fraction of protocols for 15 sources
Packet delivery fraction of protocols for 30 sources
Packet delivery fraction of protocols for 45 sources
Fig. 1. Packet delivery fraction for the 50-node model with
various numbers of sources.
Both of the protocols deliver a greater percentage of the
originateddatapacketswhenthereislittlenodemobility,converging
to 100% delivery ration when there is no node motion.
The On-demand protocol, AODV performed
particularly well, delivering almost 100% of the data packets
regardless of the mobility rate. The packet delivery of AODV is
almost independent of the number of sources that is varying number
of sources does not effect AODV that much.
DSDV performance is worst when mobility is high.
This poor performance is because of the reason that DSDV is not
a On demand protocol and it keeps only one route per destination,
therefore lack of alternate routes and presence of stale routes in
the routing table when nodes are moving at higher rate leads to
packet drops. The packet delivery of DSDV protocol depends on
the number of sources, as it is obvious from figure 1.
Average end to end delay of protocols for 15 sources
Average end to end delay of protocols for 30 sources

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Average end to end delay of protocols for 45 sources
Fig. 2. Average End to End Delay for the 50-node model with
various numbers of sources
DSDV performed pretty stable and the delay kept
about 0.04 seconds when pause time increased from 0 seconds
to 100 second. The reason is that it is a table driven protocol, so
a node does not need to find a route before transmitting packets.
So the delay is quite stable.
For AODV the delay is much more then the DSDV. As
AODV is On-demand protocol, with an increased number of
sources and high mobility there are more link failures therefore
there are more route discoveries.AODV takes more time duringthe
route discovery process as first it finds the route hop by hop and
then it gets back to the source by back tracking that route.All this
leads to delays in the delivery of data packets.
Normalized Routing Load
Figure 3 show a comparison between both the routing
protocols on the basis of normalized routing load using a different
number of sources.
Normalized routing load of protocols for 15 sources
Normalized routing load of protocols for 30 sources
Normalized routing load of protocols for 45 sources
Fig 3. Normalized routing load for the 50-node model with
various numbers of sources
As DSDV is a table driven routing protocol its overhead
is almost the same with respect to node mobility.
In cases of AODV, as the pause time increases, route
stability increases, resulting in a decreased number of routing packet
routing packet transmissions, and therefore a decrease in the routing
overhead.Arelatively stable normalized routing load is a desirable
property for scalability of the protocols,
V.CONCLUSION
This paper compared the two ad hoc routing protocols.
AODV a On – Demand routing protocol, and DSDV a table driven
protocol.
Simulation results show that both of the protocols deliver
a greater percentage of the originated data packets when there is
little node mobility, converging to 100% delivery ration when
there is no node motion. The packet delivery of AODV almost
independent of the number of sources. DSDV generates less routing
load then AODV. AODV suffers from end to end delays. DSDV
packet delivery fraction is very low for high mobility scenarios.
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