Fault Tolerant Routing in Mobile Ad hoc Networks

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Fault Tolerant Routing in Mobile Ad hoc Networks

• Yuan Xue and Klara Nahrstedt
• xue,klara_at_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
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Outline

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

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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.

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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).

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Model

• Network Model
• Faulty Node Model

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Problem Formulation

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

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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

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E2FT Algorithm (II) route estimation

• raw estimation
• Estimation
• Raw estimation
• Iterative estimation method
• Problem different estimation accuracy
• a-estimation
• Definition
• Property

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E2FT Algorithm (III) route selection

• Initially
• Progressive route refinement via
• Confirmation
• Confirm a path p if
• Dropping
• Drop a path pmin if satisfies

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Property analysis

• Bounded packet delivery rate
• Bounded route selection overhead

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Example (I)
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Example (II)
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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

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Simulation Setup

• Network settings
• 700m700m
• 50 nodes
• M faulty nodes simulation parameter
• Mobility model
• Random waypoint
• Speed 20m/s
• Pause time simulation parameter
• Default values

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Result (I) packet delivery rate
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Result (II) -- overhead
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Result (III) node mobility
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Result (IV) node mobility
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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.

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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

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Thank you very much!