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Backup Path Allocation Based on A Link Failure Probability Model in Overlay Networks. Weidong Cui, Ion Stoica, and Randy H. Katz EECS, UC Berkeley {wdc, istoica, randy}@EECS.Berkeley.EDU. Motivation. The Internet is actually a BIG overlay network.
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Backup Path Allocation Based on A Link Failure Probability Model in Overlay Networks Weidong Cui, Ion Stoica, and Randy H. Katz EECS, UC Berkeley {wdc, istoica, randy}@EECS.Berkeley.EDU
Motivation • The Internet is actually a BIG overlay network. • Link failures in an overlay network usually are not independent because they may share same links/nodes in the lower level network. • Having two orthogonal service/communication paths (a primary path and a backup path) can improve service availability. • This project studies the problem of how to find and set up two orthogonal paths based on a correlated link failure model in overlay networks.
A Link Failure Probability Model in Overlay Networks • The link failure probability model has • Single link failure probabilities • Double link failure probabilities • Assumption: probabilities are SMALL! • Path failure probabilities • Single path failure probability • Double path failure probability • How to obtain the link failure probabilities?
Backup Path Routing Algorithms • Probability Cost Routing Algorithm • Goal: find a backup path such that it minimizes the joint path failure probability given a shortest path as the primary path • Probability cost for link used in the backup path is: • Second Shortest Routing Algorithm • Find a second shortest path as the backup path which is disjoint from the primary path
Backup Path Bandwidth Allocation Algorithms • Duplicate Bandwidth Allocation • Same bandwidth on backup paths as on primary paths • Single-Link-Failure Bandwidth Allocation • Allocate bandwidth on backup paths such that it can recover from a single link failure • Zero Bandwidth Allocation • A baseline for comparison.
Simulation Experiments • Use GT-ITM to generate random network topology. • Assume the link failures in the lower level network are independent. • Calculate the link failure probabilities in the overlay network based on the link failure probabilities in the lower level network. • Simulate the link failures in the lower level network
Conclusion and Future Work • Probability-cost routing algorithm and single-link-failure bandwidth allocation algorithm have good performance on robustness and efficiency. • Probability-cost routing algorithm is fault tolerant to noise of overlay link failure probabilities. • Future Work • Test the algorithms both in NISTNet emulation testbed and in a real overlay network • Study how to obtain overlay link failure probabilities in real networks.