Restoration Mechanism and Maximum Dual Failure Restorability of Span-restorable Optical Networks

A survivable network is commonly designed to be 100% restorable to any single span failure. The restoration mechanism of networks with span restoration is not as straightforward as that of networks with dedicated path protection. The restoration of span-restorable networks can be conducted in real time or preplanned and cross-connected immediately when any failures occur. The disadvantages and advantages of these two mechanisms are discussed. Two linear programming formulations to maximize average dual-failure restorability of a network are developed. A case study shows the flaw of the k-shortest path routing in real-time routing