说明：  (AODV creates and uses two phases (1) Discovery of route and (2) Maintenance of route. Protocol uses Request (RREQ)of route, Reply (RREP) of route, Discovery of route and Error of route (RERR) control message in Maintenance of route .The beginning node initiates a connection to ending node, first it checks in the existing route table, as to whether a fresh route to that destination is available or not