Dynamic connection establishment and network re-optimization in flexible optical networks

We propose a dynamic connection establishment algorithm for flexible optical networks. When the spectrum is fragmented, blocking a connection establishment, the algorithm re-optimizes the network by shifting (“pushing”) in the spectrum domain and/or rerouting established connections. We devised appropriate algorithms that search among different combinations of shifting and rerouting alternatives and select the one with the minimum cost. Since shifting or rerouting a connection might trigger more shifting and rerouting actions, the proposed algorithms are recursive. Since the solution space can be very large, we use a threshold on the recursion depth to reduce the complexity, and also provide a tradeoff between performance and running time.