An investigation into fault recovery in guaranteed performance service connections

As high speed networks are starting to provide guaranteed performance services, it is imperative that fault recovery techniques be revised to support these new services. The authors investigate one aspect of fault recovery, in this context, the rerouting of guaranteed performance connections affected by link faults in the network. Recovery is achieved by rerouting the affected connection so as to avoid the failed link while ensuring that the traffic and performance guarantees made along the previous route are satisfied along the new route. The goal of the rerouting schemes is to reroute as much of the affected traffic as quickly and efficiently as possible. The authors investigate rerouting along the lines of two orthogonal components: the locus of reroute, which determines the node that does route selection and the new route selected; and the timing component, which determines when the individual reroute attempts are initiated. Within each of these two components they examine approaches that span the spectrum of that component. They compare all possible combinations of these approaches under a cross-section of network workloads, using in their comparisons a novel metric, the queueing delay load index, that captures both the bandwidth and delay resources required by a connection. Extensive simulation experiments were conducted on the various combinations and some of their results and analyses are presented in the paper