MANET , known as mobile Ad.Hoc network or mobile self-organized network , is a multi-hop wireless network which is self-organized, uncenter and does not depend on existing fixed infrastructure. In the network, each node operates not only as a host but also as a router. Because the coverage area of radio communication is limited, nodes could communicate only by other nodes fowarding data packets. Due to strong survivability , resistance of being damageded and convenience of building up and moving, MANET makes up the deficiency of Cellular system and cable network. So it plays an important role in many fields , such as battle field, rescue and temporary work place.Because of the dynamic topology, it is very important to choose the suitable routing protocols in MANET. So the research on routing protocols is one of the key problems in MANET. Firstly, the thesis introduces the existing routing protocols of DSDV(Destination- Seque need Distance-Vector Routing), AODV(Ad-hoc On-De- mand Distance Vector Routing), DSR(Dynamic Source Routing), TORA (Temporally-Ordered Routing Algorithm) and ZRP(Zone Routing Protocol) in detail. We evaluate DSDV, AODV and DSR based on the NS2, and compare the performances of three protocols for average packet delivery fraction, average end-to-end delay and routing load.
