Fault Tolerant Routing in Mobile Ad hoc Networks

1. Fault Tolerant Routing in Mobile Ad hoc Networks Yuan Xue and Klara Nahrstedt xue,klara@cs.uiuc.edu Computer Science Department University of Illinois at Urbana-Champaign http://cairo.cs.uiuc.edu This research was supported by the ONR MURI NAVY CU 37515-6281 grant, and the NSF EIA 99-72884EQ grant. Any opinions, findings, and conclusions are those of the authors and do not necessarily reflect the views of the above agencies

2. Outline • Motivation • Model and problem formulation • Algorithm and its analysis • Example • Discussion • Simulation results • Related work • Conclusion

3. Motivation • Most existing routing protocols need mobile nodes to cooperate with each other. • If there exist non-cooperative nodes or faulty nodes, then the performance of the current routing protocols will degrade.

4. Our approach – tolerating faulty nodes • Observation: • Ad hoc networks are highly redundant – there exist multiple paths between source and destination. • Approach: • Exploring the network redundancy through multipath routing. • Challenge: • Trade off between effectiveness (packet delivery rate) and efficiency (packet overhead).

5. Model • Network Model • Faulty Node Model

6. Problem Formulation • Assumption • Perfect knowledge of faulty nodes behaviors • Packet-delivery-rate-constrained overhead-minimization problem (PCOO) • PCOO problem is NP-complete

7. E2FT Algorithm (I) • Challenges revisit • No precise knowledge of nodes behaviors • NP-complete complexity • Algorithm overview • Route estimation (end-to-end estimation) • Estimate • Route selection • Select so that and can be reduced

8. E2FT Algorithm (II) – route estimation • raw estimation • Estimation • Raw estimation • Iterative estimation method • Problem: different estimation accuracy • a-estimation • Definition • Property

9. E2FT Algorithm (III) – route selection • Initially • Progressive route refinement via • Confirmation • Confirm a path p if • Dropping • Drop a path pmin if satisfies

10. Property analysis • Bounded packet delivery rate • Bounded route selection overhead

11. Example (I)

12. Example (II)

13. Discussion • Accommodation to node mobility • Node estimation (max-min rule) • Path estimation • Accommodation to node behavior dynamics • Soft state – long term dynamics • Dynamics during estimation • Route set discovery • Needs to integrate with route discovery protocol

14. Simulation Setup • Network settings • 700m*700m • 50 nodes • M faulty nodes – simulation parameter • Mobility model • Random waypoint • Speed: 20m/s • Pause time – simulation parameter • Default values

15. Result (I) – packet delivery rate

16. Result (II) -- overhead

17. Result (III) – node mobility

18. Result (IV) – node mobility

19. Other Approaches • Protection • SAR (Security-Aware Routing) by S. Yi et al. • Secure route discovery by Papadimitratos and Hass • URSA (Ubiquitous and Robust Security Architecture) by H. Luo et al. • Detection • Intrusion detection by Zhang and Lee • Detect misbehaving nodes by S. Marti et al. • Toleration • Blind multipath routing by Z. Hass et al.

20. Conclusion • Fault tolerant routing is an effective approach to address the problem of faulty/misbehaving nodes in ad hoc networks • E2FT can obtain high and stable packet delivery rate and acceptable additional overhead simultaneously

21. Thank you very much!