Ad hoc On-demand Distance Vector Routing (AODV)

1. Ad hoc On-demand Distance Vector Routing(AODV) • Pure on-demand protocol • Node does not need to maintain knowledge of another node unless it communicates with it • AODV includes route discovery and route maintenance. • AODV minimizes the number of broadcasts by creating routes on-demand • AODV uses only symmetric links because the route reply packet follows the reverse path of route request packet • AODV uses hello messages to know its neighbors and to ensure symmetric links

2. Path discovery • In the path discovery (RREQ) phase, source broadcasts RREQ message. • Intermediate nodes record in their route tables the address of neighbor from which RREQ is received to establish a reverse path. • When RREQ reaches destination or an intermediate node responds by unicasting a route reply (RREP) back to neighbor.

3. Path maintenance • If source node moves, reestablish the path. • If destination or intermediate node moves, send link failure notification message to each of its active upstream. • Then source reinitiates path discovery .