A two-phase approach for virtual topology reconfiguration of wavelength-routed WDM optical networks

In a WDM network, messages are carried in all-optical form using lightpaths. These set of semi-permanent light-paths may be viewed as a virtual topology. Virtual topologies are designed to optimize some objective function with traffic as the input. The virtual topology may need to be changed in response to the changing traffic patterns. This process of changing the virtual topology is called reconfiguration. We view the reconfiguration as an on-line process and it provides a tradeoff between the objective function value and the number of changes to the virtual topology. The objective function value decides how best the topology is suited for the given traffic demand. The number of changes decides the extent of disruption of traffic in the network while making a transition to the new virtual topology. We develop a heuristic based on a two-phase approach. The effectiveness of the proposed heuristics is verified by extensive simulation experiments.