Research On Shared Path Protection In Elastic Optical Networks

Elastic optical networks(EONs), based on optical orthogonal frequency division multiplexing(OFDM), have achieved widespread attention, due to its efficient spectrum utilization. In EONs, single-link failure may cause the loss of data. Therefore, network survivability has become particularly important in EONs. The protection strategy is manly divided into link-based protection policy and path-based protection policy.Although the link-based protection policy has a faster recovery time, it achieves lower resource utilization compared with the path-based protection policy. The path-based protection policy includes dedicated path protection and shared path protection.Compared with dedicated path protection, the shared path protection has higher resource utilization. Therefore, the shared path protection in EONs is the focus of this thesis.For improving the resource sharing efficiency of dynamic shared path protection in elastic optical networks, a resource efficiency survivable RSA(RESRSA) based on heuristic algorithm is proposed in the thesis. In RESRSA, an adaptive adjustment link cost function is devised to effectively select the working and protection paths. The cost function sufficiently considers the available spectrum resources and the length of light paths for both working and protection paths. In order to achieve high resource sharing efficiency, a spectrum allocation strategy, named as Minimal Cost Stable Set, is proposed to allocate spectrum for the protection paths with respect to the resource efficiency in the link cost function. And the graph coloring algorithm is introduced to select the sharing protection path with the highest resource efficiency for the request.Simulation results show that the proposed RESRSA decreases blocking probability and achieves high resource efficiency.Multipath transmission causes the differential delay among different paths and affects the usage of spectrum resources. To address the problem, a genetic multipath protection algorithm(GMPA) based on NSGA-II is proposed. According to traffic requests, the K link-disjoined paths and bandwidth assignments are designed as the population initialization scheme. A vector function is proposed to balance the path-distance difference and network spectrum resources by optimizing population classification and crowding distance sorting. For improving the algorithm search ability and convergence, an individual self-cross pattern is introduced to improve individual'sdiversity in the cross operation. And the variation range and constraint conditions of bandwidth gene are designed to speed up individual's convergence in the mutation process. GMPA algorithm can get the lowest bandwidth blocking probability, and the path-distance difference performance of GMPA is better.