Backup resource pooling in (M:N)n fault recovery schemes in GMPLS optical networks

In resilient optical networks, there is a tradeoff between the amount of resources allocated for protection versus the probability that a failed working path can not be recovered, known as protection blocking probability. Often the network topology permits multiple protected groups of working paths (WPs) to share protection bandwidth and other network resources. The Common Control and Measurement Plane (CCAMP) working group in the IETF has defined an (M:N)n shared recovery scheme, in which defined n WP groups each consisting of N WPs and M backup paths (BPs) share some or all of the BP resources. In this paper, we present an analytical model that predicts protection blocking probability as a function of BP resource sharing for this shared recovery scheme. We also propose an algorithm that efficiently manages BP resources while doing protection assignments. We provide numerical results that highlight the benefits and tradeoffs involved. Our analytical model can assist in providing engineering guidelines to service providers so that they can effectively allocate resources and manage protection and restoration in their networks.