Virtual topology transition sequence problem on WDM networks with dedicated protection

Wavelength-division multiplexing (WDM) technology has emerged as a promising technology for backbone networks. The set of all-optical communication channels (lightpaths) in the optical layer defines the virtual topology for the upper layer applications. Since the traffic demand of upper layer applications fluctuates from time to time, it is required to reconfigure the underlying virtual topology in the optical layer accordingly. However, the reconfiguration for the virtual topology is reluctantly disruptive to the network since some lightpaths should be torn down and some traffic has to be buffered or rerouted during the reconfiguration process. Therefore, it needs to have an efficient transition method to shift the current virtual topology to the new one so as to minimize the effect of the reconfiguration on the upper layer traffic. In this article, the WDM virtual topology transition sequence problem (WVTTSP) which minimizes the average weighted delay (AWD) is studied. Since the WVTTSP is NP-hard, a heuristic solution model is proposed to solve it. Simulation results show that the proposed least weighted distance first (LWDF) method can find the best result and the time spent by it is less than 4 s for a middle-sized network with 100 links and with 30 wavelengths per link.