Recovering guaranteed performance service connections from single and multiple faults

Fault recovery techniques must be reexamined in the light of the new guaranteed performance services that networks will support. We investigate the rerouting of guaranteed performance service connections on the occurrence of link faults, focussing on the aspects of route selection and establishment in the network. In a previous investi-gation, we explored some components of rerouting in the presence of single link faults in the network. In this paper we study the behavior of our techniques in the presence of multiple link faults in the network, and also examine the technique of retries to improve the success of rerouting. Our schemes are simulated on a cross-section of network work-loads, and compared using the criteria of the fraction of the affected traffic that could be rerouted, the time to reroute and the amount of resources consumed in the network. A novel metric, the Queueing Delay Load Index, which captures both the bandwidth and delay demands made on the network by a connection, is used to present and analyze the results