Failure-independent path protection with p-cycles: efficient, fast and simple protection for transparent optical networks

Failure independent path-protecting (FIPP) p-cycles are an extension of the basic p-cycle concept which retains the property of pre-cross-connection of protection paths while acheiving end-to-end failure-independent path protection switching against either span or node failures. An issue with the current method of shared-backup path protection (SBPP) in a transparent optical network is that spare channels for the backup path must be cross-connected on-the-fly upon failure. It takes extra time and signaling to make the required cross-connections but, more importantly, until all connections are made it is not actually known if the backup optical path has adequate transmission integrity. Thus, pre-failure certainty about optical path integrity is an important reason to have backup paths fully pre-connected before failure. FIPP p-cycles support the same failure-independent, end-node activated switching of SBPP but with fully pre-connected protection paths. FIPP p-cycles may therefore be especially attractive for transparent optical networks. FIPP p-cycle network designs also exhibit capacity efficiency that is characteristic of path-oriented schemes. We think it is the only scheme known with these very high efficiencies, failure independence, and the property of fully pre-cross-connected protection paths.