Spare capacity planning using survivable alternate routing for long-haul WDM networks

Spare capacity planning is designed to find the minimum amount of spare capacity to be allocated throughout a network so that the network can survive from network component failures. In this paper, the spare capacity planning problem is investigated for long-haul wavelength division multiplexing (WDM) networks. A three-step method is developed for solving the problem. First, heuristic approaches are used to select both candidate working routes and protection routes in order to achieve approximate optimal performance while maintaining a computational feasibility. Second, traffic requests are distributed on the obtained candidate working and protection routes optimally using genetic algorithms (GA). Finally wavelengths are assigned to working lightpaths and shared protection lightpaths. The major advantage of the new approach is the ability to incorporate nonlinear constraints and nonlinear cost functions into the GA, which are introduced by sharing protection links between shared risk link groups (SRLG). Moreover, by considering SRLG constraints in the spare capacity planning phase, wavelengths can be allocated to each shared protection route before failures happen, so that shorter restoration latency can be achieved. Numerical results illustrate that the proposed approach is more cost-effective than the single-path protection method.