DSR Optimization: Route Caching

•Each node caches a new route it learns by any means

•When node S finds route [S,E,F,J,D]to node D, node S also learns route [S,E,F] to node F

•When node K receives Route Request [S,C,G] destined for node, node K learns route [K,G,C,S] to node S

•When node F forwards Route Reply RREP[S,E,F,J,D],node F learns route [F,J,D] to node D

•When node E forwards Data [S,E,F,J,D]it learns route [E,F,J,D] to node D

Dynamic Source Routing: Advantages

•Routes maintained only between nodes who need to communicate

–reduces overhead of route maintenance

•Route caching can further reduce route discovery overhead

•A single route discovery may yield many routes to the destination, due to intermediate nodes replying from local caches

Dynamic Source Routing: Disadvantages

•Packet header size grows with route length due to source routing

•Flood of route requests may potentially reach all nodes in the network

•Potential collisions between route requests propagated by neighboring nodes

–insertion of random delays before forwarding RREQ

•Increased contention if too many route replies come back due to nodes replying using their local cache

–Route Reply Stormproblem