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Fault Management in Mobile Ad-Hoc Networks

Fault Management in Mobile Ad-Hoc Networks. by Tridib Mukherjee. Transient Faults in Mobile Ad-Hoc Networks. Mobility of the Nodes Error Prone Medium Link Failures Low Battery Power Node Corruption. Fault Tolerance.

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Fault Management in Mobile Ad-Hoc Networks

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  1. Fault Management in Mobile Ad-Hoc Networks by Tridib Mukherjee

  2. Transient Faults in Mobile Ad-Hoc Networks • Mobility of the Nodes • Error Prone Medium • Link Failures • Low Battery Power • Node Corruption

  3. Fault Tolerance • Ability of a system to perform its function correctly even in the presence of internal faults. • Makes the network system more dependable. • Hides the faults from the user. • Two basic kinds of Fault Tolerance : Proactive and Reactive.

  4. Self Stabilization • Stabilizes a Distributed System to a legitimate state from any arbitrary initial state. • Used as a Proactive Fault Tolerant Scheme. • There are 2 properties : Closure and Convergence.

  5. Self-stabilizing Multicast Routing Protocols For Mobile Ad-Hoc Networks • Shortest Path Spanning Tree (SPST) • Used in this project • Maintains Shortest Path from source to destination. • Beacon Messages provide information about neighbors. • Recreates the tree in case of faults. • Unnecessarily propagates limited faults across the network.

  6. Fault Containment • Contains the fault in the region where it has occurred • Improves stabilization time Considerably. • Increases Computational and Communication Overhead. • Does not contain faults in all the desired cases in Mobile Ad-Hoc Networks. • Tradeoff needed for optimal Energy Efficiency while managing the faults.

  7. Fault-containment Algo. can_stabilize :

  8. Propose for Adaptation • Adapt to the changing Fault Scenarios. • Use Self Stabilization where Fault Containment can not contain the faults. • Use Fault Containment where it can contain the faults.

  9. Fault Classification • Fault-Containable (FC) Faults • Fault can be contained using Fault Containment • Non-Fault-Containable (NFC) Faults • Fault Containment can not contain the faults • Self-stabilization and Fault-containment have same performance • Fault-containment executes self-stabilization internally • Fault-containment adds computational overhead

  10. Valid SPST Tree Level 0 R Level 1 A M X Level 2 Y Level 3 Level 4

  11. M moves out Level 0 R A Level 1 M X Level 2 Y Level 3 C D can_stabilize(Y) is false can_stabilize(X) is false can_stabilize(C) is false can_stabilize(D) is false Level 4

  12. This is NFC fault R A X Level 2 Y Level 3

  13. Neighborhood of Y is different Level 0 R A Level 1 M X Level 2 Y Level 3 C D can_stabilize(Y) is true can_stabilize(A) is false can_stabilize(C) is false can_stabilize(D) is false Level 4

  14. FC faults • The scenario of the previous slide • Faults occurred due to corruption are FC faults • Both NFC and FC faults can occur in multiple nodes simultaneously • For NFC faults, self stabilization is executed internally

  15. Two FC faults within 2 hops R M Y A B X 0 1 2 3 4 5 • Level of A gets corrupted to 6 • M moves out and X becomes the parent of Y • Both the FC faults become Non-containable • Distance of 2 hops is named as Containability Limit (CL)

  16. Reason • Gp(Y) and Gp(A) are true • Can_stabilize(Y) and Can_stabilize(A) are false • So Fault Containing Algorithm executes self-stabilization internally • FC faults becomes NFC if they occur within CL

  17. Improved_Can_Stabilize • Check if local action can nullify Gp in all the two hop neighbors instead of one hop neighbors as in the original algorithm • Otherwise check if local actions in all the one hop neighbors can eradicate fault in all the two hop neighbors

  18. Improved Fault-containment

  19. Reasoning • Gp(Y) and Gp(A) are true • Can_stabilize(Y) and Can_stabilize(A) are also true • Fault Containing Algorithm executes self-stabilization internally only if faults are NFC • Containability Limit is 0

  20. Simulation • Simulation is done in NS2 • Comparison between Self-stabilization, Fault-containment and Improved Fault-containment • Simulation is done for NFC and FC faults as well as multiple FC faults occurring within CL • Performance is measured in terms of Beacon Intervals

  21. NFC Fault Simulation Result

  22. FC faults with distance greater than CL

  23. FC faults with distance less than CL

  24. Advantages & Disadvantages • If a fault can be contained, it is contained regardless of its occurrence in the network • Costs more communication overhead if a fault is not containable

  25. References • Sukumar Ghosh, Arobinda Gupta, Sriram V. Pemmaraju. ”Fault-containing network protocols”. Proceedings of the 1997 ACM symposium on Applied computing, p.431-37, April 1997, San Jose, California, United States. • Sukumar Ghosh, Arobinda Gupta, T. Herman, Sriram V. Pemmaraju. Faultcontaining Self-Stabilizing Algorithms”. 15th Annual ACM Symposium on Principles of Distributed Computing, 1996, pp. 45-54.

  26. References (Contd…) • Sandeep K. S. Gupta, Pradip K. Srimani. ”Self-stabilizing multicast protocols for ad hoc networks”. Journal of Parallel and Distributed Computing 63(1): 87-96 (2003)

  27. Questions?

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