Network restoration under a single link or node failure using Preconfigured Virtual Cycles

This paper presents a design algorithm for networks with a restoration mechanism that provides failure-independent, end-to-end path protection to a set of given demands under a single link or node failure with a focus on optical networks. The restoration routes are provided on preconfigured cycles, where each of the demands is assigned a single restoration route and specific restoration wavelengths on a segment of one cycle (splitting is not allowed). The number of reserved restoration wavelengths may vary from one link to the next on a cycle; hence, we refer to these cycles as Preconfigured Virtual Cycles (PVCs). The network design algorithm consists of three major parts. The first part generates a large number of candidate PVCs. Our algorithm allows assignment of certain demands that have common failure scenarios to the same PVC. The second part selects a set of PVCs from among the candidates, attempting to minimize the total reserved restoration cost while ensuring that each demand is assigned to one PVC. This is achieved by solving a set covering problem followed by elimination of duplicate assignments. The third part resolves conflicts of wavelength assignments.