Design and Dimensioning of Logical Survivable Topologies Against Multiple Failures

In IP-over-WDM networks, protection can be offered at the optical layer or at the IP layer. Today, it is well acknowledged that synergies need to be developed between the IP and optical layers in order to optimize the resource utilization and to reduce the costs and the energy consumption of future networks. In this paper, we study the design of logical survivable topologies for service recovery against multiple failures, including SRLG-shared risk link group-failures in IP-over-WDM networks. We propose a new optimization model, called SURLOG_CGILP, based on a column generation path formulation. It is highly scalable and allows the exact solution of several benchmark instances, which have only been solved with the help of heuristics so far. In the numerical experiments, we investigate the dimensioning of the physical links assuming IP restoration against multiple-link failures. We observe that the redundancy ratios (recovery over primary ratios for the bandwidth requirements) that are obtained are similar to the redundancy ratios reported for optical protection.