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. E 2 FT 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. E 2 FT Algorithm (II) – route estimation raw estimation Estimation Raw estimation Iterative estimation method Problem: different estimation accuracy  -estimation Definition Property

9. E 2 FT Algorithm (III) – route selection Initially Progressive route refinement via Confirmation  Confirm a path p if Dropping  Drop a path p min 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 E 2 FT can obtain high and stable packet delivery rate and acceptable additional overhead simultaneously

21. Thank you very much!