ILP approaches to study interconnection strategies for multi-ring networks in the presence of traffic grooming

Dual Node Interconnection (DNI) multi-ring topologies in a traffic grooming context are studied by means of the optimal solutions given by integer linear programming (ILP) formulations. Three ILP models are proposed, namely, to design interconnection networks without protection (WP) and for Virtual Ring (VR) and Drop & Continue (D&C) protection methods. Numerical results using a 13-node network accommodating 10 different traffic matrices are presented. The objective function is to minimize the network cost by reducing the number of Add&Drop Multiplexers (ADM). In addition, the electronic processing on the gateway nodes has also been assessed. This metric allows more comprehensive comparisons between Virtual Ring and Drop & Continue approaches for protection since we show that ADM optimized-solutions might produce transit traffic hot-spots in Digital Cross Connects (DXC) at interconnection nodes.