Robust solution for splitter placement in all-optical WDM networks

In all-optical wavelength-division multiplexing (WDM) networks, splitters are used to realize multicast. The multicast-capable cross-connects are the cross-connects with passive power splitters in the all-optical network. Placing splitters at all of the nodes is considered to be expensive in the all-optical WDM network. Optimally selecting a subset of nodes to place the splitters can reduce the cost and this placement problem is called the splitter placement problem. The multicast demands of splitter placement problem are deemed to be static in previous researches, but the demands of real network are uncertain. In this paper, a robust optimization strategy is proposed to optimally solve the splitter placement problem with uncertain demands and a fixed number of multicast-capable cross-connects. The different multicast demands are described as a set of scenarios each with a known probability in a demand forecast. The robust optimization strategy is modeled as an Integer Programming model, whose primary objective is to minimize a regret function. Regret function of the robust solution models the over resource provisioning of all the possible scenarios in the network, which is the difference between the resource provisioning really used in scenario and the optimal resource provisioning that could be used. Using robust optimization strategy to solve the splitter placement, an optimal placement of splitters can be gained, which make the resource provisioning of each possible scenario close to the optimal resource consumption and robust for all-optical multicast.