An Investigation into Fault Recovery in Guaranteed Performance Service Connections†

As high speed networks are starting to provide guaranteed performance service, it is imperative to revise fault recovery techniques to support this new service. In this paper we 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. We 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 we examine approaches that span the spectrum of that component. We compare all possible combinations of these approaches under a cross-section of network workloads, using in our comparisons a novel metric, the Queuing 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 their results and analysis are presented in the paper. hhhhhhhhhhhhhhhhhh †This research was supported by the National Science Foundation and the Defense Advanced Research Projects Agency (DARPA) under Cooperative Agreement NCR-8919038 with the Corporation for National Research Initiatives, by AT&T Bell Laboratories, Hitachi, Ltd., Hitachi America, Ltd., Pacific Bell, the University of California under a MICRO grant, and the International Computer Science Institute. The views and conclusions contained in this document are those of the authors, and should not be interpreted as representing official policies, either expressed or implied, of the U.S. Government or any of the sponsoring organizations.