A New Objective Criterion and Rounding Techniques for Determining Virtual Topologies in Optical Networks

This letter addresses the problem of determining virtual topologies in wavelength-routed WDM optical networks. To solve this problem, it is necessary to determine the set of lightpaths which comprise the virtual topology. Packet-switched traffic is then routed over this set of lightpaths, completely independent of the physical topology. Common objectives include minimizing congestion or packet hop distance. In this letter, we introduce an additional objective criterion, discuss its importance, and derive an effective lower bound. Several solution approaches use MILP formulations solved using LP-relaxations and rounding techniques. Proposed are alternative rounding schemes for determining more effective virtual topologies.