Virtual topology reconfiguration for node failures in wavelength routed optical networks

In Wavelength Routed Wavelength Division Multiplexing (WR-WDM) networks, a set of lightpaths (all-optical communication paths) defines the virtual topology. In the event of a node failure, the virtual topology may be partitioned so that a set of nodes may not able to communicate with. another set of nodes. In such a case, the restoration of disturbed lightpaths may be indispensable. Hence, it may be necessary to alter the existing virtual topology. Altering of a virtual topology is called as virtual topology reconfiguration. In this paper we propose a methodology for reconfiguration of virtual topology in the event of a node failure. The proposed virtual topology reconfiguration methodology strikes a balance between the objective function value and number of changes committed to the virtual topology and assures all-to-all communication path (either using single hop or multi-hop path) in 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 traffic disruption in the network while performing changes in the existing virtual topology.