The research describes the performance of the three routing protocols (AODV,DSR,TORA)in different network situations, specially varying the size of the networks. AODV shows a considerable better performance over the others for any number of nodes. TORA and DSR show moderate performance for minimum number of nodes, where in the case of large networks, DSR shows some performance rather than TORA. OPNET Modeler 10.5 is used to model the network and to simulate the protocols. The thesis will show a future performance improvement for more routing protocols using OPNET Modelers or other Network Simulators.