Link failures are part of the day-to-day operation of a network due to many causes such as maintenance, faulty interfaces, and accidental fiber cuts. Commonly deployed link state routing protocols such as OSPF react to link failures through global link state advertisements and routing table recomputations causing significant forwarding discontinuity after a failure. Careful tuning of various parameters to accelerate routing convergence may cause instability when the majority of failures are transient. To enhance failure resiliency without jeopardizing routing stability, we propose a local rerouting based approach called failure insensitive routing. The proposed approach prepares for failures using interface-specific forwarding, and upon a failure, suppresses the link state advertisement and instead triggers local rerouting using a backwarding table. With this approach, when no more than one link failure notification is suppressed, a packet is guaranteed to be forwarded along a loop-free path to its destination if such a path exists. This paper demonstrates the feasibility, reliability, and stability of our approach.
Bibliographical noteFunding Information:
Manuscript received July 29, 2004; revised December 11, 2005; approved by IEEE/ACM TRANSACTIONS ON NETWORKING Editor T. Griffin. This work was supported in part by the National Science Foundation under Grant ANI-0073819 and Grant ITR-0085824 and CAREER Award NCR-9734428 and Award CNS-0448272.
- Fast rerouting
- Interface-specific forwarding
- Transient failures