Lightpath-protecting p-Cycle selection for protected working lightpath envelope

Abstract

Protected Working Lightpath Envelope (PWLE) is a promising scheme developed by us to provision survivable services for dynamic traffic [3]. As a a path-oriented protection strategy based on lightpath-protecting p-Cycles, PWLE has the advantages of high capacity efficiency, avoidance of wavelength conversion, good blocking performance and guaranteed optical transmission quality compared with conventional schemes. It partitions the total network capacity into a working layer and a static protection layer in which a set of lightpath-protecting p-Cycles are configured. The lightpath-protecting p-Cycles in PWLE are not designed particularly for a set of pre-defined paths. Instead, they are selected to protect an envelope of working channels that can be used flexibly for working routing. The protected working channels are grouped based on the related Attach Nodes which are defined as the nodes one-hop away from the on-cycle nodes. To design PWLE, pre-computation of a subset of candidate cycles and cycle selection within the subset are crucial. Due to the uniqueness of the lightpath- protecting p-Cycle, no existing algorithms can be applied directly for cycle selection for PWLE. Moreover, existing algorithms for pre-computation of candidate cycles are mostly span-protection- oriented. Therefore, we propose the AttachNode-Based Cycle Generation (ANCG) algorithm for pre-computation of candidate cycles and three algorithms for lightpath-protecting p-cycle selection for PWLE. Numerical results show that ANCG can generate a small subset of cycles with high capacity efficiency. Meanwhile, the algorithms for cycle selection work well with much reduced computational time. © 2008 IEEE.