Hybrid alternative routing strategies in communication networks

Abstract

This paper re-visits a model that was used to compare Fixed and Dynamic Alternate Routing (FAR and DAR). These Alternative Routing (AR) schemes, as do all current AR schemes, use 2-1ink alternative routes. We remove this restriction, and identify optimal sequences of alternative routes consisting of 2 or more links. We construct a simple two stage hybrid AR scheme which first uses FAR on the optimal sequences, and then uses DAR on the overflow calls that cannot be carried on the optimal alternative routes. The first stage optimally redistributes the overload flows and the second stage exploits the random spare capacity that emerges in the network. The model is evaluated using discrete-event simulation. We show that, for a wide range of offered loads, the hybrid scheme offers a substantially lower blocking probability and a higher expected rate of earning revenue than either DAR or FAR. The hybrid scheme is robust in terms of preserving network revenue in the event of link failures and inaccuracies in traffic measurement.