Optimization Model and Algorithm for Routing and Spectrum Assignment in Elastic Optical Networks

In this paper, the problem of routing and spectrum assignment for static connection requests in elastic optical networks (EONs) is studied. Two different ratios of blocking formations are adopted, and a global constraint optimization model is established to minimize the ratio of blocking in the network. First, we propose an availability index of the frequency slots in the path. Second, a strategy of routing is designed by considering the two indexes of path length and availability index to judge the quality of the path. Then, a greedy strategy, which can obtain the largest availability index in the path after the frequency slot allocated, is proposed for the sake of assigning the spectra effectively. Simulation experiments were carried out in two network topologies. The two different ratios of blocking are obtained for different sorting strategy for connection requests and the number of connection requests. The experimental results show that the routing and spectrum assignment scheme designed in this paper can get a small ratio of blocking.