Research On P-cycle Heuristicalgorithm In Optical Network

Optical network is the backbone transmission network for information transmission. However,due to the harm caused by optical network failures, optical network survivability is particularlyimportant. P-cycle is an effective optical network survivability protection technology, it can notonly achieve quick recovery like circle protection, but also have high resource utilization like meshprotection.P-cycle protection algorithm is a heuristic algorithm and it is divided into two steps: p-cycleconstruction and p-cycle capacity allocation. This paper studies the algorithms of p-cycleconstruction and improves the classic heuristic p-cycle construction Grow algorithm. In the Growalgorithm, all of the intermediate cycles are chosen to expand, however, different intermediatep-cycle has different priori efficiency and the selection of intermediate p-cycle will finally affect thewhole performance of p-cycles. Study finds that if all of the intermediate cycles are chosen toexpand, the whole performance of p-cycles is not the best. To solve this problem, this paper choosesa prior efficiency as the standard, the top N intermediate p-cycles that generated by primary cyclewho have the highest prior efficiencies are chosen to expand. Using the VC simulation platform tosimulate the improved Grow algorithm, results show that different parameter N will lead to differentwhole performance of p-cycles, when N=2, the algorithm gets the best performance, the number ofconstructed p-cycles reduces more than half, the whole prior efficiency of p-cycles increases andthe resource utilization improves.After p-cycle construction is completed, capacity is allocated for p-cycle in order to achievenetwork protection. Study finds that the classic heuristic CIDA algorithm only applies to thenetwork whose capacity is large enough, but can’t provide good protection for the network whennetwork capacity is relatively small. To solve the problem, this paper puts forward a new heuristicspace capacity allocation algorithm. It utilizes the constructed p-cycle to allocate the capacityreasonably on the basis of spare capacity and by the expanded standard of maximum work capacity.Using the simulation platform to simulate the new algorithm, results show that whether the networkcapacity is large enough or limited, the new algorithm can use less spare capacity to protect morework capacity, and reduce the number of configuration p-cycle.