Simulation and Analysis of Ad-hoc On-demand Distance
Vector Routing Protocol
Md. Monzur Morshed
Tiger Hats
Department of Computer Science and Engineering East West University, Mohakhali
Dhaka-1212, Bangladesh
m.monzur@gmail.com
Md. Rezaur Rahman Mazumder
Tiger Hats
Department of Computer Science and Engineering East West University, Mohakhali
Dhaka-1212, Bangladesh
m_rezaur@yahoo.com
Md. Habibur Rahman
Tiger Hats
Department of Computer Science and Engineering East West University, Mohakhali
Dhaka-1212, Bangladesh
mmmhabib@gmail.com
K. A. M. Lutfullah
Tiger Hats
Assistant System Manager East West University, MohakhaliDhaka-1212, Bangladesh
kallolrahman@yahoo.com
ABSTRACT
Mobile Ad-hoc Network is a decentralized network. There are many routing protocols have been proposed for Mobile Ad-hoc Network. In this paper, we have simulated AODV routing protocol to visualize the performance of AODV Routing Protocol. AODV is a reactive protocol; it uses traditional routing tables. This means that for each destination exist one entry in routing table and uses sequence number, this number ensure the freshness of routs and guarantee the loop-free routing. To evaluate the performance of AODV routing protocol, the simulation results were analyzed by graphical manner and trace file based on QoS metrics such as Delay, Jitter. The simulation result analysis verifies the AODV routing protocol performance.
Keywords
AODV, MANET, QoS, Network Simulator (NS2).
1.
INTRODUCTION
Mobile Ad-hoc Network (MANET) is a composition of a group of mobile, wireless nodes which cooperate in forwarding packets in a multi-hop fashion without any centralized administration. In MANET, each mobile node acts as a router as well as an end node which is either source or destination. AODV is perhaps the most well-known routing protocol for MANET [1]. It offers quick adaptation to dynamic link conditions, low processing and memory overhead, low network utilization, and determines unicast routes to destinations within the ad hoc network [2].
Another usual characteristic is that it is an On-demand algorithm; it determines a route to the destination only when packets send to destination. If the wireless nodes are within the range of each other, the routing is not necessary. If a node moves out of range then the node will not be able to communicate with others directly, intermediate nodes are needed to organize the network which takes care of the data transmission.
2.
AODV PROTOCOL MECHANISM
Ad-hoc On-demand Distance Vector (AODV) routing protocol is essentially a combination of both DSR and DSDV protocol [2]. It borrows the basic on-demand mechanism of Route Discovery and Route Maintenance from DSR protocol, plus the use of hop-by-hop routing, sequence numbers, and periodic beacons from DSDV protocol [3]. The AODV protocol is loop-free and avoids the count-to-infinity problem by the use of sequence numbers. AODV protocol uses a simple request-reply mechanism for route discovery [4]. Source node require a route to sends a Routes Request message to its neighbors. Source address and Request ID fields uniquely identify the ROUTE REQUEST packet to allow nodes to discard any duplicates they may receive. Sequence number of source and the most recent value of destination sequence number that the source has seen and the Hop count field will keep track of how many hops the packet has traveled. When source include destination sequence numbers in its route request that actually last known destination sequence number for a particular destination. Every intermediate nodes store most recent sequence number of source. If a neighbor has a route to destination then it informs the source node. If neighbors have no route then it rebroadcast RREQ and increment hop count. Eventually a route must be found if exists. In reverse path calculation, all nodes remember source of the RREQ. When a route is found then it working backwards, route is discovered. The receiver looks up the destination in its route table.
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To test freshness it compares destination sequence number, if RREQ packet destination sequence number is greater than the Route destination sequence numbers assumes route is still present and remains unused. If route is found Route Reply (RREP) message is returned to source.
3.
SIMULATION TOPOLOGY
Simulation environment consists of 16 wireless mobile nodes which are place uniformly and forming a Mobile Ad-hoc Network, moving about over a 1000 × 1000 meters area for 40 seconds of simulated time. We have used standard two-ray ground propagation model, the IEEE 802.11 MAC, and omni-directional antenna model of NS2. We have used AODV routing algorithm and interface queue length 50 at each node. The source nodes are respectively 6, 15 and 5 and the receiving nodes are respectively 0, 1 and 11.
Figure 1: Simulation Topology
4.
SIMULATION DESCRIPTION
Table 1: Simulation parameters
Method Value
Channel type Channel/Wireless channel
Radio-propagation model Propagation/Two ray round
Network interface type Phy/wirelessphy
MAC type Mac/802.11
Interface queue type Queue/Drop Tail
Link Layer Type LL
Antenna Antenna/omni antenna
Maximum packet in ifq 50
Area (m×m) 1000×1000
Number of mobile nodes 16
Source type UDP, TCP
Simulation Time 40 sec
Routing protocol AODV
5.
QoS METRICS
We used different parameter of QoS metrics such as delay, jitter, packet drop, round trip time, and throughput to understand the behavior of AODV Routing Protocol.
6.
SIMULATION RESULT
6.1
Drop
The routers might fail to deliver (drop) some packets if they arrive when their buffers are already full. Some, none, or all of the packets might be dropped, depending on the state of the network, and it is impossible to determine what will happen in advance. The receiving application may ask for this information to be retransmitted, possibly causing severe delays in the overall transmission. Table 2 shows the scenario of two types of packet (TCP, UDP) flow from source to destination node where UDP packet drop rates of UDP are greater than TCP packets. We use Constant Bit Rate (CBR) as a User Datagram Protocol (UDP).
Table 2: Packet Drop of TCP and UDP
Packet type Send Receive Drop
TCP 759 673 86
UDP 1963 1229 734
6.2
Throughput
Throughput is the measurement of number of packets passing through the network in a unit of time [5]. This metric show the total number of packets that have been successfully delivered to the destination nodes and throughput improves with increasing
nodes density.
6.2.1
Transmission Throughput
202752 202240 202240
Range of Time (second)
S
Figure 2: Transmission Throughput for UDP
166144
Range Of Time (second)
S
Figure 3: Transmission Throughput for TCP
Figure 3 shows the time interval 24 to 32 was maximum amount TCP packets send from the source node because it shows the maximum job was done by the source node. In this particular unit time interval sending throughput was high due to less traffic and source and destination distance node close to each other.
6.2.2
Receiving Throughput
139916
Range of Time (second)
R
Figure 4: Receiving Throughput for UDP
Figure 4 shows the maximum receiving throughput in the time interval of 16 to 24 as well as maximum amount UDP packets actually received by the intended destinations because in that particular time interval the send node and receive node distance is less, free of channel for those packets.
Figure 5 the time range 8 to 16 maximum TCP packets received because in this particular time range destination node face less traffic and free channel which shows the maximum work was done by the intended destinations. And the rest of the time interval received throughput reasonably stable for TCP packets. From the Figure 2 to Figure 5 shows throughput which is the number of routing packets (TCP, UDP) received successfully by AODV routing protocol.
166144
Range Of Time (second)
S
Figure 5: Receiving Throughput for TCP
6.3
Delay
A specific packet is transmitting from source to destination and calculates the difference between send times and received times. Delays due to route discovery, queuing, propagation and transfer time are included in the delay metric [6].
0
Figure 6: Send Time VS Delay Graph for UDP
0
Figure 7: Send Time VS Delay Graph for TCP
Figure 7 shows after certain time interval the delay increases because of the node distance and busy nodes. The delay decreases when the source and destination nodes close to each other while having free channel and minimum traffic. From Figure 6 and Figure 7 we conclude that there is trend of increasing delay with increasing distance between source and destination, busy channel, busy nodes and node density. When nodes keep on moving more frequently there will be more topology changes and more link breakages. This will cause activation of routes discovery process to find additional links. Thus packets have to wait in buffers until new routes are discovered. This results in larger delay.
6.4
Jitter
Jitter is the variation of the packet arrival time. In jitter calculation the variation in the packet arrival time is expected to minimum. The delays between the different packets need to be low if we want better performance in Mobile Ad-hoc Networks.
-8
Figure 8: Send Time vs. Jitter Graph for UDP
Figure 8 we can see few spikes are comparatively higher than others because there were long delays, destination node far away from source node, more traffic and busy channel. In rest of the time UDP packets delay was low.
-2
Figure 9: Send Time VS Jitter Graph for TCP
Figure 9 shows when the send time 10 jitter values was close to zero and after certain time interval jitter value increased and later repeated old scenario for the TCP packets. There is a trend of increasing of jitter value with increasing of delay between the packets. Jitter values of routing packets (TCP, UDP) are affected by packets delay if we compare Figure 7 with Figure 9 for TCP data packets and Figure 6 with Figure 8 for UDP data packets.
6.5
Round Trip Time (RTT)
Round-trip time (RTT), also called round-trip delay, is the time required for a signal pulse or packet to travel from a specific source to a specific destination and back again. For each connection, TCP maintains a variable, RTT that is the best current estimation of round-trip time to the destination. When a segment is sent, a timer is started, both to see how long the acknowledgement takes and to trigger a retransmission if it takes too long.
Figure 10: Send Time Vs RTT
during the packet transmission. From Figure 10 Round Trip Time (RTT) also affected by TCP delay which is shown in Figure 7.
7.
CONCLUSION
In our simulation, we have simulated and analyzed the AODV routing protocol using different parameter of QoS metrics. As a reactive protocol AODV transmits network information only on-demand. We have analyzed two types of data packets TCP, UDP and both packet drop rate are respectively 11.33% and 37.39%.
For DSR and AODV Routing Protocol, packet delivery ratio is independent of offered traffic load, with both protocols delivering between 85% and 100% of the packets in all cases [4]. Comparing results we conclude that AODV routing protocol perform well under voice or data transmission but poor performance for video transmissions as well as lack of Quality of Service (QoS).
Simulation result shows the performance of TCP and UDP packets with respect to delay, throughput, jitter, round trip time. As a result, we can say that for real time applications we need more robust routing protocol which will perform better than AODV routing protocol.
8.
REFERENCES
[1] Davide Cerri, Alessandro Ghioni, “Securing AODV: The A-SAODV Secure Routing Prototype,” IEEE Communications Magazine, February 2008.
[2] C. Perkins, E. Belding-Royer and S. Das, “Ad hoc On-Demand Distance Vector (AODV) Routing,” IETF RFC, 3561, July 2003.
[3] Geetha Jayakumar and G. Gopinath, “Performance
comparison of two on-demand routing protocols for Ad-hoc networks based on random way point mobility model,” American Journal of Applied Sciences, June 2008, pp. 659-664.
[4] Geetha Jayakumar and Gopinath Ganapathy, “Performance Comparison of Mobile Ad-hoc Network Routing Protocol,” International Journal of Computer Science and Network Security (IJCSNS 2007), vol. 7, no. 11, November 2007, pp. 77-84.
[5] Rekha Patil, DrA.Damodaram, “Cost Based Power Aware Cross Layer Routing Protocol,” International Journal of Computer Science and Network Security (IJCSNS 2008), vol. 8 no. 12, December 2008, pp. 388-393.
[6] S H Manjula, C N Abhilash, Shaila K, K R Venugopal, L M Patnaik, “Performance of AODV Routing Protocol using Group and Entity Mobility Models in Wireless Sensor Networks,” Proceedings of the International
