1. Fault-Tolerant Routing
Providing Fault-Tolerant Ad-hoc Routing Service in Adversarial Environments
Yuan Xue and Klara Nahrstedt
Fault-Tolerant Routing
Observation
High Redundancy
Problem
Trade-off between packet delivery ratio and overhead
Motivation when misbehaving nodes exist in ad hoc networks, the performance of its routing protocols will significantly degrade.
Possible Approaches
Isolation
Authentication infrastructure
Intrusion detection
Toleration
Route the packets in the presence of misbehaving nodes
Misbehavior Assumptions
Byzantine faulty behavior in routing and forwarding
No denial of service attack to the MAC/physical layer
I: percentage that network has a “good” path
II: percentage that DSR route protocol discovers a “good” path
III:percentage that DSR uses a “good” path
I N F O R M A T I O N T R U S T I N S T I T U T E
University of Illinois at Urbana-Champaign

2. Best-effort FT Routing
Providing Fault-Tolerant Ad-hoc Routing Service in Adversarial Environments
Yuan Xue and Klara Nahrstedt
Method end-to-end performance measurement
Security Assumptions
Source and destination are well-behaved nodes
Priori trust relationship between source and destination
Strategies
Assume bad, until confirmed good
Assume good, until confirmed bad
Assured FT routing
Start with all available paths
Refine the route progressively
Drop unnecessary path
Confirm a good path
Lower bound on packet delivery ratio
Upper bound on overhead
Algorithm
Property
Best-effort FT Routing
Start with the shortest path
Hypothesis test
Discard the bad path
Proceed with next shortest path
Upper Bound on false positive probability
Lower Bound on packet delivery ratio
I N F O R M A T I O N T R U S T I N S T I T U T E
University of Illinois at Urbana-Champaign

3. percent of misbehaving nodes
Providing Fault-Tolerant Ad-hoc Routing Service in Adversarial Environments
Yuan Xue and Klara Nahrstedt
Results
1.1 1
0.9
0.8
Greatly improved packet delivery ratio
Controlled Overhead
Packet delivery ratio
0.7
DSR
AFTR
BFTR
Multipath
0.6
0.5
0.4 10 20 30 40
percent of misbehaving nodes
Conclusion
Fault tolerant routing is an efficient and effective approach to address the problem of misbehaving nodes in ad hoc networks
Acknowledgement
ONR MURI CU fund
Professor Nitin Vaidya and Pradeep Kyasanur for their comments and helpful suggestions
I N F O R M A T I O N T R U S T I N S T I T U T E
University of Illinois at Urbana-Champaign