Comparison of Protection Mechanisms: Capacity Efficiency and Recovery Time

High efficiency in capacity utilization and fast restoration are two primary goals of survivable design in optical networks. Shared backup path protection has been shown to be efficient in terms of capacity utilization, due to the sharing of backup capacity. However, sharing of backup capacity also complicates the restoration process, and leads to slow recovery. Ring-type protection in mesh topology, on the other hand, has the advantage of fast restoration. The p-cycle scheme is the most efficient ring-type protection method in terms of capacity utilization. Recently, the concept of pre-cross-connected protection was proposed to increase the recovery speed of shared path protection. We overview these protection methods and their failure recovery processes. The recovery time of these schemes are compared analytically. To compare the capacity efficiency, we formulate integer programming optimization problems for three protection methods in static traffic scenario, considering wavelength continuity constraint. We investigate the effect of network connectivity on the performance of capacity utilization of the methods by experimenting on topologies with different average nodal degrees.