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  1. 1. Viral Parekh, K. H. Wandra / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 3, Issue 1, January -February 2013, pp.467-472 Effects of Traffic Load and Mobility on AODV, DSR and DSDV Routing Protocols in MANET Viral Parekh1, K. H. Wandra21 Computer Engineering Department, C. U. Shah College of Engineering and Technology, Gujarat Technological University 2 Principal, C. U. Shah College of Engineering and Technology, Gujarat Technological UniversityAbstract Mobile Ad-hoc network is an In either case, the routing protocols typically specifyinfrastructure less multi hop wireless network that each node makes periodic advertisements towithout the aid of any centralized administration. supply current routing information to its neighbors.MANET is a self configuring and self organizing The neighbor is then able to determine routes tocollection of mobile nodes. As the nodes provided network nodes based on the received information.mobility, the routing is a very complex task in The node can also include the information it hasMANET. In MANET each node works as a host received into its own advertisements, as essentialas well as a router to forward the packets from according to the protocol. In the case of link-statesource to destination. As in MANET the network protocols, the advertisements can have informationtopology is dynamic and frequently changes, so about every known link between other routingrouting protocols should be designed to meet the agents in the network. On the other hand, Distance-requirement of the MANET. There are various vector protocols supply next-hop information aboutprotocols available for the routing. This paper all destinations in the network. For Internet routingmainly compares the working of AODV with protocols, routing information is aggregatedDSR and DSDV for various traffic load and according to a well-defined subnet structure in orderdifferent mobility. Also in future we can compare to reduce the size of the advertisements. Routes toAODV with other routing protocols. all hosts on a particular subnet are represented by a single route entry to a routing prefix, and theKeywords- MANET, NS-2, AODV. DSR, DSDV, addresses of all the hosts on the subnet are thenZRP, TORA throughput, PDR, End-to-end delay required to use the routing prefix as the initial bits of their network-layer address. Subnets with longerI. INTRODUCTION prefixes (i.e., more specific addressing) are Basically there are two types of networks: themselves typically aggregated into larger subnetsInfrastructure based and Infrastructure less networks. with shorter prefixes. At the core (center) of theMobile Ad-hoc networks (MANETs) are Internet, there is finally a requirement to advertiseinfrastructure less networks as there is no existing all of the routing prefixes with no furtherinfrastructure available. Currently Ad hoc networks aggregation possible. The routers in the Internetare enjoying extraordinary research interest, and are (core and otherwise) are often considered to be theexpected to provide opportunities for utilization of infrastructure of the Internet. Ad hoc network studynetwork applications in new scenario in which has suggested that such periodic advertisements maytoday’s internet-based communication paradigms are be uneconomical because the presumptions aboutno longer applicable. Ad-hoc networks are formed in fixed relationships between hosts and subnets are nota situation where no infrastructure is available and necessarily valid in these networks. There may nothaving no central administration. For MANET no be any flat relationship between wireless, mobilepredetermined subnet structure is known. Ad hoc devices and any distinguished routing node. Therenetworks are considered to be composed of mobile may not be any infrastructure, and hence ad hocwireless devices, so the interconnection pathways networks are often characterized to be infrastructurebetween the devices can change rapidly. less networks. Since the communication medium of interest is often wireless, it is matter to capacity As in MANET each device is free to move constraints, and is less appropriate for periodicindependently, links between the devices may advertisements containing volumes of routing data.change frequently. Routing is the process offorwarding the packets from source to the Two techniques for solving this problemdestination with efficient performance. As in are 1) to limit the amount of information advertisedMANET devices are moving frequently, routing is and 2) to establish routes only on demand so thatthe most complex process. There are basically two periodic advertisements are no longer required.types of traditional routing protocols: Link-State Though, such on-demand routing protocols have therouting and Distance Vector routing protocols. disadvantage that routes are often unavailable at the 467 | P a g e
  2. 2. Viral Parekh, K. H. Wandra / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 3, Issue 1, January -February 2013, pp.467-472time an application first needs them. This means that Acknowledgement (RREP-ACK) are message typesapplications in networks using such routing defined by AODV [3]. Due to simple AODVprotocols often experience initial delay during the messages require little computations to minimizetime it takes to establish a route between the processing overhead. AODV allows mobile nodes tocommunication endpoints. find routes quickly for new destination, and does not require nodes to maintain routes to destinations thatII. ROUTING PROTOCOLS are not in active communication. AODV allowsMainly there are three types of routing protocols: mobile nodes to react to link breakages and changes (1) Proactive (Table-Driven) in network topology in a timely manner. When links (2) Reactive (On-Demand) break, AODV causes the affected set of nodes to be (3) Hybrid notified so that they are able to invalidate the routes Proactive routing protocols find paths for using the lost link. The operation of AODV is loop-all source-destination pairs in advance and stores in free, and by avoiding the Bellman-Ford "counting tothe routing tables. Each node periodically exchanges infinity" problem offers quick convergence when thethe routing information by broadcasting. The adhoc network topology changes (typically, when aprotocols are also known as table-driven routing node moves in the network).protocol. Destination-Sequenced Distance-VectorRouting (DSDV) is a proactive routing protocol. B. Dynamic Source Routing (DSR) Dynamic Source Routing (DSR) [4] is a Reactive routing protocols discover a path reactive routing protocol which is source-initiatedwhen a packet needs to be transmitted and no known rather than hop-by-hop and is based on the theory ofpath exists between source and destination. So the source-based routing rather than table-based. Everyprotocol is known as on-demand routing protocol. In node in the network maintains a route cache to storecase of routing failure occurs the protocol discovers the complete and ordered list of nodes throughan alternate path. Dynamic Source Routing (DSR) which the packet must pass to reach to theand Ad-hoc On-demand Distance Vector (AODV) destination. Since the hop sequence is known to therouting protocol are the most popular routing source, any loop in routing can be excluded, and theprotocols. routing decision is determined when sending out data packets. Thus data packets are appended with Hybrid routing protocols are the the same complete hop sequence in the packetcombination of proactive and reactive routing header; intermediate nodes just forward the packetprotocols. Hybrid routing protocol use the proactive to the next hop along the hop sequence. A node thatas well as reactive routing protocols for route desires to send a packet to other node first checksfinding. For the route finding between two networks its entry in the route cache. If the route is availablehybrid protocols are used. To find a route in the then it uses that path to transmit the packet andnetwork proactive routing protocols are used when node also attaches its source address on the find a route between two different networks If the route is not available in the cache or the entryreactive routing protocols are used (i.e. for short in the cache is expired, the sender initiates routedistance proactive routing protocols are used and for discovery process by broadcasting a new Routelong distance reactive routing protocols are used). Request packet message tagged with a uniqueZone Routing Protocol (ZRP) is an example of Request ID set by the source. The Request ID, withhybrid routing protocol. the source node address, helps to identify Route Requests uniquely and discards any duplicate RouteA. Ad-hoc On-Demand Distance-Vector Requests. While receiving a non-duplicate Route Ad-hoc On-demand Distance Vector Request, if the node is neither the destination nor a(AODV) [1] routing protocol is the most popular node with a valid route to the destination, it appendsreactive unicast routing protocol, essentially its own address into the message and re-broadcastscombination of DSDV and DSR. AODV uses it to its neighbors; otherwise, the node can sendmechanism of route maintenance from DSDV and back a Route Reply with a complete and ordered listroute discovery from DSR. AODV was first of intermediate nodes from the source to theproposed in an Internet engineering task force destination. Throughout propagation of the Route(IETF) Internet draft in fall of 1997. AODV was Reply back to the source, any intermediate node anddesigned to meet the following goals: [2] the source can get the hop sequence, the entire route• Minimal control overhead. to the destination, and record it in one’s route cache.• Minimal processing overhead. In DSR no periodic routing-update messages are• Multi-hop path routing capability. used. The route is used till some link on that• Dynamic topology maintenance. hop sequence breaks. The link breakage is• Loop prevention. detected by using a wireless MAC layer Route Requests (RREQs), Route Replies retransmission and acknowledgement mechanism(RREPs), Route Errors (RERRs) and Route Reply or passive acknowledgements as described in 468 | P a g e
  3. 3. Viral Parekh, K. H. Wandra / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 3, Issue 1, January -February 2013, pp.467-472[5]. Once a link breakage occurs at an III. COMPARISON OF AODV, DSR AND DSDVintermediate node, the node sends a Route Error For the comparison the simulation tool usedmessage back to the source node. Along the traverse is NS-2[8] which is highly preferred by researchof the Route Error, the broken link and the links community.after it are removed from any route cache that TABLE 1: SIMULATION PARAMETERScontains this hop. Any route containing that Serial Parameters Valuebroken link is also removed by the source. If the No.source still needs to send data packets to thatdestination, a new route discovery process is 1 Number of nodes 50initiated; otherwise, there is no need to discover a 2 Simulation Time route. Several optimization options proposed 3 Area 500*500m2by DSR are: (1) salvaging used for repairing a 4 Max Speed 20 m/sdisconnected route locally; (2) promiscuous 5 Traffic Source CBRlistening used for finding smaller hop-count route;and (3) piggybacking the bad link on its next Route 6 Pause Time (sec) 0, 20, 10, 30 ,40,Request, which can assist to remove the broken link 100in the caches of other nodes, and keep other nodes 7 Packet Size 512 Bytesaway from generating Route Replies containing the 8 Packet Rate 4 Packets/sbad link. 9 Max. Number of 10,20,30,40 connectionsC. Destination-Sequenced Distance-Vector 10 Bandwidth 10MbpsRouting (DSDV) 11 Delay 10ms Destination-Sequenced Distance-Vector 12 Mobility model used Random wayRouting (DSDV) [6] is a distance vector routing pointprotocol based on classical Bellman-Ford routingalgorithm. It was developed by C. Perkins and The performance metrics that are taken intoP.Bhagwat in 1994. Each node in DSDV maintains consideration for the comparison are:next hop table, which it exchanges with its neighbor. 1) Throughput 3) Packet Delivery RatioPeriodic full-table broadcast and event-driven (PDR)incremental updating are two types of next-hop table 2) Packets Dropped 4) End-to-end delayexchange. It eliminates route looping, increasesconvergence speed, and reduces control message A. Simulation Results : Effect of mobilityoverhead, by having a monotonically increasing The number of nodes is taken as 50 and theeven sequence number for each node, which maximum number of connection as 20. For theincrements whenever a new routing-update message analysis of the effect of mobility, pause time wasis sent out, thus letting other nodes know about varied from 0 seconds (high mobility) to 100which routing information is fresher. Routing table seconds (low mobility). Graphs shown in Fig (1-4)also contains the hop count to the destination, next show the effect of Mobility for AODV, DSR andhop to the destination and currently known largest DSDV protocols with respect to varioussequence number of the destination in addition to the performance metrics.destination node address. Packets are routed usingthe information available in the routing table. The 1) Pause Time Vs Throughputrelative frequency of the full-table broadcast andincremental updating is determined by node 250mobility. The source node appends a sequence T h 200number to each data packet sent during a next-hop rtable broadcast or incremental updating. This 150 ( o ksequence number is propagated by all nodes 100 DSR u breceiving the corresponding distance-vector updates, g p 50 DSDVand is stored in the next-hop table entry of these h s AODV 0 )nodes. A node updates its route to a destination, after preceiving a new next-hop table from its neighbor, u 0 10 20 30 40 100only if the new sequence number is the same as the trecorded one, but the new route is shorter or if the Pause Time (sec)new sequence number is larger than the recordedone. A settling time is estimated for each route in Fig. 1 Pause Time Vs Throughputorder to further reduce the control messageoverhead. A node updates to its neighbors with a Throughput of DSDV is poor at lowernew route only if the settling time of the route has pause times (high mobility), therefore performanceexpired and the route remains optimal [7]. of DSDV protocol decreases as mobility increases 469 | P a g e
  4. 4. Viral Parekh, K. H. Wandra / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 3, Issue 1, January -February 2013, pp.467-472compared to on demand protocols DSR and AODV. 4) Pause Time Vs End-to-end DelayAODV and DSR perform better at high mobility. 2502) Pause Time Vs Packets Dropped E n D 200 d e 2500 l 150 P D T a 100 DSR 2000 a r o y DSDV 50 c o 1500 AODV ( k p DSR E m 0 e p 1000 n s 0 10 20 30 40 100 ) t e DSDV d s d 500 AODV Pause Time (sec) 0 0 20 40 Fig. 4 Pause Time Vs End-to-end Delay Pause Time (sec) As DSDV always holds optimal paths to all other destinations in their routing tables, delayFig. 2 Pause Time Vs Packets Dropped involved in sending data packets at highest mobility is very less. Mobility decrease end-to-end delay DSDV performs poorly as it is dropping increase in DSDV. As mobility increases AODVmore number of packets at high mobility. This is performs better as it adopts hop-by-hop routing.attributed to only one route per destination DSR performs better at lower and moderate trafficmaintained by DSDV. Each packet that the MAC load as it uses source routing.layer is unable to deliver is dropped since there areno alternate routes. Both AODV and DSR allow B. Simulation Results: The effect of traffic loadpackets to stay in the send buffer for 30 seconds for The network was simulated for highroute discovery and once the route is discovered, on mobility scenario keeping the pause time 0 seconds.that route data packets are sent to be delivered at the The number of connections was varied as 10, 20, 30destination. If route fails, both DSR and AODV find and 40 connections to study the effect of traffic loadnew path within 30 seconds thereby minimizing the on the network. Graphs in Fig (5-8) show the effectpossibility of packet drop. Traffic Load for AODV, DSR and DSDV protocols with respect to various performance metrics.3) Pause Time Vs Packet Delivery Ratio (PDR) 1) Max. Number of Connections Vs 150 Throughput D R P e 100 400 a l a t DSR T c i 50 i h 300 k v DSDV o r ( e e 0 200 ( AODV o k t r % DSR u b 0 20 40 ) y 100 DSDV g p Pause Time (sec) h s AODV 0 ) p u 10 20 30 40 tFig. 3 Pause Time Vs PDR Maximum Number of Connections Packet delivery ratio of DSDV is very lessas compared to on demand protocols DSR andAODV at lower pause time (high mobility). AODV Fig. 5 Maximum Number of Connections Vsand DSR perform best among all at high mobility Throughputbecause both allow packets to stay in the send buffer As the traffic load increases both on-for 30 seconds for route discovery and once the demand protocols work better compared to DSDV.route is discovered, on that route data packets aresent to be delivered at the destination. Using AODV99.38% PDR is obtained. 470 | P a g e
  5. 5. Viral Parekh, K. H. Wandra / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 3, Issue 1, January -February 2013, pp.467-4722) Max. Number of Connections Vs Packets 1400 Dropped E 1200 n D 5000 d e 1000 P D l 4000 a 800 a r t 3000 600 DSR c o o y k p DSR DSDV 2000 400 ( e p DSDV E m AODV t e 1000 n s 200 AODV ) s d 0 d 0 10 20 30 40 10 20 30 40 Maximum Number of Connections Maximum Number of ConnectionsFig. 6 Maximum Number of Connections Vs Fig. 8 Maximum Number of Connections Vs End-Packets Dropped to-End Delay As the traffic load increases packets IV. CONCLUSIONS AND FUTURE WORKdropped will also increase. The reason is bandwidth The analysis of adhoc routing protocolsrequirement increases as load increases. Each packet indicate that DSDV is more preferable for a networkthat the MAC layer is unable to deliver is dropped in with low mobility and less number of nodes. TheDSDV since there are no alternate routes. DSR and performance of DSR which uses source routings isAODV drops less packets compared to DSDV. preferable for the normal network of general nature with moderate traffic and moderate mobility.3) Max. Number of Connections Vs Packet Investigation also suggests that AODV performs Delivery Ratio (PDR) better for the robust scenario where high mobility, nodes are dense, the amount of traffic is more, area 120 is large, and network pattern sustains for longer D 100 period. e In future AODV can be compared with P 80 l other routing protocols like TORA and ZRP for a 60 various traffic loads and different mobility. i DSR c 40 v DSDV k 20 REFERENCES e AODV e r 0 [1] Perkins, C. E. and Royer, E. M.; "Ad-hoc t On-Demand Distance Vector Routing", y 10 20 30 40 … Proceedings of the 2nd IEEE Workshop on Maximum Number of Connections Mobile Computing Systems and Applications (WMCSA.99), New Orleans,Fig. 7 Max. Number of Connections Vs PDR LA, USA, February 1999, pages 90-100. [2] “Evolution and future directions of the ad AODV and DSR to build the routing hoc on-demand distance-vector routinginformation as and when they are required to send protocol”, Elizabeth M. Belding-Royer,data, which makes them more adaptive and results in Charles E. Perkins, 2003 Elsevier B.V,better performance with respective to high packet doi:10.1016/S1570-8705(03) fraction. AODV delivers more packets at [3] Mobile Ad Hoc Networking Workinghigh traffic load compared to DSR. Group – AODV, Max. Number of Connections Vs End-to-end [4] D. B. Johnson, D. A. Maltz and Y.C. Hu, delay “The Dynamic Source Routing Protocol for As DSDV always holds optimal paths to all Mobile Ad Hoc Networks (DSR)”, IETFother destinations in their routing tables, delay Draft,, April 2003.involved in sending data packets at lower traffic load [5] Maltz, D. A.; Broch, J.; Jetcheva, J. andis very less. As traffic load increases AODV Johnson, D. B.; .The Effects of On-Demandperforms better as it adopts hop-by-hop routing. Behavior in Routing Protocols for MultihopDSR performs better at lower and moderate traffic Wireless Ad Hoc Networks., IEEE Journalload as it uses source routing. on Selected Areas in Communications Special Issue on Mobile and Wireless 471 | P a g e
  6. 6. Viral Parekh, K. H. Wandra / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 3, Issue 1, January -February 2013, pp.467-472 Networks, August 1999, Vol. 17, No. 8, pages 1439-1453.[6] Perkins, C. E. and Bhagwat, P.; "Highly Dynamic Destination-Sequenced Distance- Vector Routing (DSDV) for Mobile Computers", Proceedings of the ACM SIGCOMM.94 Conference on Communications Architectures, Protocols and Applications, London, UK, August 1994, pages 234-244.[7] “Wireless Ad Hoc Networks” Zygmunt J. Haas, Jing Deng, Ben Liang, Panagiotis Papadimitratos, and S. Sajama Cornell University School of Electrical and Computer Engineering.[8] Tutorial for Simulation-based Performance Analysis of MANET Routing Protocols in ns-2By Karthik sadasivam ISSN 472 | P a g e