Optimal routing for protection and restoration in an optical network
In this paper we provide a centralized method for optimally selecting the set of active and backup paths in an optical transport network in the cases of shared-path restoration and 1:1 protection schemes. We provide novel mixed integer linear programming (MILP) formulations for both the schemes, for a network with full wavelength conversion capability. The given formulations are not restricted to consider single link failures: the concept of fault event is introduced to handle the possibility that multiple links go simultaneously under fault. The optimization objective includes the total capacity requirement plus an additional term related to the active paths reliability. We use a simple decomposition heuristic to support the resolution process. The optimization is solved for various sample scenarios in order to evaluate the resource saving achieved with the shared-path restoration scheme. The impact of different factors such as topology, traffic demand and structure of failures on the resource saving is analyzed. Also, we provide guidelines about handling differentiated levels of protection within the framework of the proposed formulations.
restoration fault protection route optimization