Optimization of DSR routing protocol in MANET using passive clustering

Routing algorithms in Mobile Ad hoc Networks like DSR, AODV use flooding as the primary mechanism for discovery of routes in the network. In flooding, each node forwards flood packets to its neighbors so as to ensure that the packets reach the intended destination. Forwarding of redundant flood packets create extra overhead on network bandwidth. However, only a subset of nodes need to forward the packet to make it reach its destination. Clustering has been proven as an efficient mechanism to reduce flooding overhead in MANETs. Active Clustering algorithms use explicit control packets to create and maintain clusters whereas passive clustering piggybacks the control information in the outgoing data packets thus significantly reducing control overhead. The proposed algorithm integrates Passive Clustering with DSR routing protocol. Route Discovery phase of DSR floods the Route Request packets in the entire network. However, the proposed algorithm creates the clusters in the network in the initial phase of Route Discovery process and once the clusters are formed only a subset of nodes will forward the Route Request packets. This approach reduces the overhead on bandwidth by curtailing the flooding of packets and thereby increasing the packet delivery ratio. The simulation results show that optimized DSR algorithm enhances the packet delivery ratio by minimum of 20% and reduces the RREQ flooding by a minimum of 30%.