Shortest Path First with Emergency Exits

Under heavy and dynamic traffic, the SPF routing algorithm often suffers from wild oscillation and severe congestion, and results in degradation of the network performance. In this paper, we present a new routing algorithm (SPF-EE) which attempts to eliminate the problems associated with the SPF algorithm by providing alternate paths as emergency exits. With the SPF-EE algorithm, traffic is routed along the shortest-paths under normal condition. However, in the presence of congestion and resource failures, the traffic can be dispersed temporarily to alternate paths without route re-computation. Simulation experiments show that the SPF-EE algorithm achieves grater throughput, higher responsiveness, better congestion control and fault tolerance, and substantially improves the performance of routing in a dynamic environment.