Performance Evaluation of a Distributed Scheme for Protection against Single and Double Faults for MPLS

MPLS can be used to provide network robustness to faults through path protection techniques. In this paper we present a dynamic model supporting different classes of end-to-end protection, including protection against Single Fault and Dual Fault, with and without sharing of backup bandwidth. Beyond link and node failures we also consider protection against Shared Risk Link Group (SLRG) failure. An interesting feature of the proposed scheme is the ability to offer service differentiation with respect to the recovery probability, by coupling the differentiation on the number of backup paths with bandwidth assignment policy. In this paper we describe the underlying algorithms for route selection and backup bandwidth sharing. The route selection is based on explicit load-dependent routing of service and backup paths. We show by simulation that the proposed route selection algorithm is effective in improving the network utilization. We discuss two alternative implementations of our model: distributed and partially centralized. The primary concern with the distributed approach is the message overhead implied by link-load dissemination, e.g. by flooding. However we show by simulation that message overhead can be taken under control by adopting a well-tuned adaptive overhead reduction algorithm. Our conclusion is that both distributed and partially-centralized implementation are feasible.