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Two general approaches: * Source (“path”) routing - Source specifies entire route: places complete path to destination in message header: A – D – F – G * Destination (“hop-by-hop”) routing - Source specifies only destination address in the header

Ad-hoc On-demand Distance Vector (AODV) routing

  1. Source node A sends route request (RREQ) with target node E
  2. RREQ messages are flooded by receiving nodes
  3. When an intermediate node re-broadcasts a Route Request, it sets up a reverse path pointing towards the source
  4. When RREQ reches target node, target node sends a route reply (RREP) back on the reverse path.

Furthermore: An intermediate node (not the destination) may also send a Route Reply (RREP) provided that it knows a more recent path than the one previously known to sender S. To determine whether the path known to an intermediate node is more recent, destination sequence numbers are used.