A practical perspective in designing mesh networks based on 1 : N self-healing wavelength division multiplexing rings

A fundamental task of the optical layer in modern telecommunication systems consists of providing a fast protection mechanism against possible faults in the network. A particularly attractive protection technique in the optical layer is the so called shared line protection, in which network lines are protected using shared resources. A previous work of the authors formally describes the problem of minimizing the total wavelength mileage necessary in a Wavelength Routing mesh network to provide shared line protection. However, two practical issues remain to be addressed: the solution feasibility in presence of design constraints and the problem complexity in large size networks. This paper presents an approach to addressing the above two issues based on: 1) an algorithm that identifies a feasible solution with the minimal, possibly null, violation of the design constraints, 2) an intelligent pruning technique of the search space that reduces the complexity of the optimization problem. Using the proposed approach, a study on the total wavelength mileage is carried out for the European network (19 nodes) and the Pan American network (79 nodes) to assess the influence that some design constraints have on this cost function.