Local Rerouting for Handling Transient Link Failures

Link failures are part of the day to day operation of a network due to various causes such as maintenance, faulty interfaces, and accidental fiber cuts. Due to several delays in detection, propagation and recomputation, intra-domain routing protocols may take tens of seconds to minutes after a link failure to resume forwarding of packets to the affected destinations. During this period, some destinations would be unreachable and the corresponding services unavailable. Careful tuning of various parameters to accelerate routing convergence may cause routing instability when the majority of failures are transient. To improve failure resiliency without jeopardizing routing stability, we propose a local rerouting approach. Under this approach, upon a link failure, adjacent router suppresses global updating and instead initiates local rerouting. All other routers infer potential link failures from packet’s flight, precompute interface dependent forwarding tables and route around failed links without explicit link state updates. This article demonstrates feasibility, reliability and stability of the proposed approach.