Extension of segment protection for bandwidth efficiency and differentiated quality of protection in optical/MPLS networks

This paper investigates the problem of dynamic survivable lightpath provisioning against single node/link failures in optical mesh networks employing wavelength-division multiplexing (WDM). We unify various forms of segment protection into generalized segment protection (GSP). In GSP, the working path of a lightpath is divided into multiple overlapping working segments, each of which is protected by a node/link disjoint backup segment. We design an efficient heuristic which, upon the arrival of a lightpath request, dynamically divides a judiciously-selected working path into multiple overlapping working segments and computes a backup segment for each working segment while accommodating backup sharing. Compared to the widely-considered share-path protection scheme, GSP achieves much lower blocking probability and shorter protection-switching time for a small sacrifice in control and management overhead. Based on generalized segment protection, we present a new approach to provisioning lightpath requests according to their differentiated quality-of-protection (QoP) requirements. We focus on one of the most important QoP parameters—namely, protection-switching time— since lightpath requests may have differentiated protectionswitching-time requirements. For example, lightpaths carrying voice traffic may require 50-ms protection-switching time while lightpaths carrying data traffic may have a wide range of protection-switching-time requirements. Numerical results show that our approach achieves significant performance gain which leads to a remarkable reduction in blocking probability. While our focus is on optical WDM network, the basic ideas of our approaches can be applied to Multi-Protocol Label Switching (MPLS) networks with appropriate adjustments, e.g., differentiated bandwidth granularities.