“Ad-hoc On-Demand Distance Vector Routing”

1. “Ad-hoc On-Demand Distance Vector Routing” A dynamic routing algorithm for mobile ad-hoc networks

2. AODV Characteristics • On-demand routing • Symmetric links • Distance vector algorithm • Route table

3. Goals • Discovery only when necessary • Distinguish between neighborhood detection and route maintenance • Disseminate change information to those neighbors most likely to be in need

4. Path Discovery • Broadcast RREQ • <src_addr, src_seq_#, broadcast_id, dest_addr, dest_seq_#, hop_cnt> • Unique <src_addr, broadcast_id> • Path Setup • Reverse • Forward

5. Reverse Path Setup • src_seq_# • dest_seq_# • Reverse path • Timeout D S

6. Forward Path Setup • Bi-directional link? • Route current? • Unicast back to neighbor RREP • <src_addr, dest_addr, dest_seq_#, hop_cnt, lifetime> D S

7. Forward Path Setup • Each node on path • forward pointer • updates timeout • records dest_seq_# • Nodes not on path timeout • Propagate first, then only new information D S

8. Route Table • Destination • Next Hop • Number of hobs (metric) • Sequence number for the destination • Active neighbors for this route • Expiration time for the route table entry

9. Path Maintenance • Link failure • Timeout on ‘Hello’ • Packet forwarding error • Unsolicited RREP • Propagates to active path members • Fresh sequence number • Hop count is infinity • Path repair via RREQ

10. Local Connectivity • ‘Hello’ message • Identity • Sequence Number • Neighbors heard • TTL = 1 • hello_interval • allowed_hello_loss

11. Local Connectivity • rreq_retries • Bi-directional connectivity • Inactive neighbors

12. Simulation Results • Number of nodes set to 50, 100, 500, and 1000 • Voice and data traffic • allowed_hello_loss and rreq_retries determined to be optimal at 2 • Scalable

13. Current Status • AODV submitted as an Internet Draft • Multicast • Intermediate node route rebuilding • Goodbye ‘Hello’? • Locality of association and QoS • delay • bandwidth assurances

14. Conclusions • Longer route establishment latency But... • Intermediate node route return • Immediate report of link outage • Stale routes aged out

15. Comparison • “A Performance Comparison of Multi-Hop Wireless Ad Hoc Network Routing Protocols” • DSDV, TORA, DSR, AODV • Conclusion: “DSR Rules!” • “Performance Comparison of Two On-demand Routing Protocols for Ad Hoc Networks” • DSR, AODV • Delay and throughput • DSR better for low loads • AODV better for high loads

16. References • Charles E. Perkins and Elizabeth M. Royer. “Ad-hoc On-Demand Distance Vector Routing.”Proceedings of the 2nd IEEE Workshop on Mobile Computing Systems and Applications, New Orleans, LA, February 1999, pp. 90-100. • Charles E. Perkins, Elizabeth M. Royer, and Samir R. Das. “Ad-hoc On-Demand Distance Vector Routing.”IETF Internet Draft, draft-ietf-manet-aodv-05.txt, March 2000 (Work in Progress). • J. Broch, D. Maltz, D. Johnson, Y. Hu, and J. Jetcheva. “A Performance Comparison of Multi-Hop Wireless Ad Hoc Network Routing Protocols.” Proceedings of the Fourth Annual ACM/IEEE International Conference on Mobile Computing and Networking (MobiCom'98) • Samir R. Das, Charles E. Perkins, and Elizabeth M. Royer. “Performance Comparison of Two On-demand Routing Protocols for Ad Hoc Networks.”Proceedings of the IEEE Conference on Computer Communications (INFOCOM), Tel Aviv, Israel, March 2000, p. 3-12.