A disjoint route-sets approach to design of path-protecting p-cycle networks

Recent work has proposed the concept of failure-independent path-protecting (FIPP) p-cycles as a pre-connected, failure independent, path-protecting network architecture [A. Kodian, W. D. Grover (2005)]. FIPP p-cycles extend p-cycles by adding the property, like shared backup path protection (SBPP), of providing end-to-end failure independent path switching against either span or node failures. Especially in a transparent or translucent optical network, the property of pre-cross-connection of protection paths can be even more important than just increasing restoration-speed: when optical protection paths are pre-cross-connected, they can be guaranteed in advance to work when required. FIPP p-cycles therefore offer a fully pre-connected, alternative to SBPP in which protection paths must be assembled on the fly from spare wavelength channels. Design results from small networks in [A. Kodian, W. D. Grover (2005)] showed that FIPP p-cycle designs can be as efficient as SBPP but it is very difficult to design larger networks using the ILP design model in [A. Kodian, W. D. Grover (2005)]. We now develop a new ILP model and a related heuristic method for FIPP p-cycle design that produces network designs with much faster runtimes. Results indicate that the heuristic generates FIPP p-cycle designs that have total capacity costs within 10-18% of optimally designed SBPP solutions.