Mobile ad hoc network (MANET) is an autonomous system of mobile nodes connected by wireless links. Each node operates not only as an end system, but also as a router to forward packets. The nodes are free to move about and organize themselves into a network. These nodes change position frequently. The main classes of routing protocols are Proactive, Reactive and Hybrid. A Reactive (on-demand) routing strategy is a popular routing category for wireless ad hoc routing. It is a relatively new routing philosophy that provides a scalable solution to relatively large network topologies. The design follows the idea that each node tries to reduce routing overhead by sending routing packets whenever a communication is requested. In this paper an attempt has been made to compare the performance of two prominent on demand reactive routing protocols for MANETs: Ad hoc On Demand Distance Vector (AODV), Dynamic Source Routing (DSR) protocols. DSR and AODV are reactive gateway discovery algorithms where a mobile device of MANET connects by gateway only when it is needed. As per our findings the differences in the protocol mechanics lead to significant performance differentials for both of these protocols. The performance differentials are analyzed using varying simulation time. These simulations are carried out using the ns-2 network simulator. The results presented in this work illustrate the importance in carefully evaluating and implementing routing protocols in an ad hoc environment.

1. Hadi Sargolzaey, Ayyoub Akbari Moghanjoughi and Sabira Khatun, ―A Review and Comparison of Reliable Unicast Routing Protocols For Mobile Ad Hoc Networks, IJCSNS International Journal of Computer Science and Network Security, VOL.9 No.1, pp. 186-196, January 2009.
2. Mobile Ad-hoc Networks (MANET), http://www.ietf.org/html.charters/ manetcharter.html. (1998-11-29)
3. J. P. Macker and M. S. Corson, "Mobile Ad Hoc Networking and the IETF", ACM SIGMOBILE Mobile Computing and Communications Reviews, Vol. 2, No. 2, pp. 9-14, January 1998.
4. Changling Liu, Jörg Kaiser, "A Survey of Mobile Ad Hoc Network Routing Protocols", the University of Magdeburg, October 2005.
5. Murthy, S. and J.J. Garcia-Luna-Aceves, “An Efficient Routing Protocol for Wireless Networks”, ACM Mobile Networks and App. J., Special Issue on Routing in Mobile Communication Networks, Oct. 1996, pp. 183-97.
6. C. E. Perkins and P. Bhagwat, “Highly Dynamic Destination-Sequenced Distance-Vector Routing (DSDV) for mobile computers”, ACM Computer Communication Review, Vol. 24, No.4, (ACM SIGCOMM’94) Oct. 1994, pp.234-244.
7. G. Pei, M. Gerla and T.-W. Chen, “Fisheye State Routing in Mobile Ad Hoc Networks”, In Proceedings of the 2000 ICDCS Workshops, Taipei, Taiwan, Apr. 2000, pp. D71-D78.
8. D. Johnson, D. A. Maltz, “Dynamic source routing in ad hoc wireless networks”, in Mobile Computing (T. Imielinski and H. Korth, eds.), Kluwer Acad. Publ., 1996.
9. C.E. Perkins and E.M. Royer. “Ad hoc on demand Distance Vector routing”, mobile computing systems and applications, 1999. Proceedings. WMCSA ’99. Second IEEE Workshop on, 1999, p90 - p10.
10. Z. J. Haas. “The Zone Routing Protocol (ZRP) for ad hoc networks”, Internet Draft, Nov. 1997.
11. M. Joa-Ng and I-Tai Lu, “A peer-to-peer zone-based two level link state routing for mobile ad hoc net-works”, IEEE on Selected Areas in Communications, vol. 17, no. 8, pp.1415 1425, 1999.
12. Navid Nikaein, Christian Bonnet and Neda Nikaein, “HARP - Hybrid Ad Hoc Routing Protocol”, in proceeding of IST 2001: International Symposium on Telecommunications, Iran/Tehran 2001.
13. Y. B. Ko and N. H. Vaidya. “Location Aid Routing (LAR) in mobile ad hoc networks”, In Proc. ACM/IEEE MOBICOM, Oct. 1998.
14. S. Basagni, I. Chlamtac, V. Syrotiuk and B. WoodWard, “A Distance Routing Effect Algorithm for Mobility (DREAM)”, Proc. 4th MOBCOM, 1998.
15. Broustis, G. Jakllari, T. Repantis, and M. Molle. “A Performance Comparison of Routing Protocols for Large-Scale Wireless Mobile Ad Hoc Networks”, Technical Report, University of California, Riverside, 2006.
16. Fang Xie, Lei Du, Yong Bai, Lan Chen, “Energy Aware Reliable Routing Protocol for Mobile Ad-Hoc Networks”, IEEE Communication Society, WCNC 2007 proceedings.
17. Nen-Chung Wang, Yung-Fa Huang, Jhu-Chan Chen, “A stable weight-based on-demand routing protocol for mobile ad hoc networks”, Elsevier Information Sciences 177,
18. Laura Marie Feeney, ―A taxonomy for routing protocols in mobile ad hoc networks, Technical report, Swedish Institute of Computer Science, Sweden, 1999.
19. C.E. Perkins and E.M. Royer, ―Ad hoc On Demand Distance Vector Routing, University of California, Santa Barbara.
20. Elizabeth M. Royer and Chai-Keong Toh, ―A review of current routing protocols for ad hoc mobile wireless networks, Technical report, University of California and Georgia Institute of Technology, USA, 1999.
21. Ad-hoc distance vector protocol for mobile ad hoc network http://www.olsr.org/docs/report_html/node16.html#adhoc_aodv#adhoc_aodv –accessed on may 2009.
22. Natrajan Meghanathan, ―A Location Prediction-Based Reactive Routing Protocol to Minimize the Number of Route Discoveries and Hop Count per Path in Mobile Ad Hoc Networks- Department of Computer Science, Jackson State University, Jackson, MS 39217, USA.
23. Vincent D. Park and M. Scott Corson, ―Temporally-Ordered Routing Algorithm (TORA) Version 1: Functional specification, Internet draft, draft-ietf-manettoraspec- 01 .txt, August 1998.

Ad hoc On Demand Distance Vector (AODV) Distance Source Routing (DSR) Mobile Ad Hoc Network (MANET)