Lightpath admission control and rerouting in dynamic flex-grid optical transport networks

In dynamic flex‐grid optical transport networks, Lightpath Admission Control (LAC) is the task of finding a Routing and Spectrum Assignment (RSA) solution for a current lightpath request; otherwise, the request is blocked if there are not enough free available resources. When rerouting is supported, one or more currently established lightpaths can be rerouted and/or assigned with a different spectrum in order to accommodate the current lightpath request. We propose LAC methods based on mixed integer linear programming that provide a RSA solution for the current request aiming to maximize the acceptance probability of future lightpath requests. When rerouting is supported, we consider that only one currently established lightpath can be rerouted. We compare the proposed methods with the traditional shortest path‐based approach through simulation. Without lightpath rerouting, the blocking probability is significantly improved. With lightpath rerouting, the number of rerouting operations is significantly decreased while the blocking probability is marginally improved. Moreover, the blocking fairness between lightpaths with different spectrum widths is improved both with and without lightpath rerouting. In all cases, the CPU times of the mixed integer linear programming approaches are a few seconds, on average.