Abstract
Multilayer network design has received significant attention in current literature. However, the explicit modeling of IP/MPLS over OTN over DWDM in which the OTN layer's technological constraints are specifically considered has not been investigated before. In this paper, we present an optimization design model for protecting an IP/MPLS over OTN over DWDM three-layer network. While considering the technological constraints of each layer, we provide a protection mechanism at each layer that guarantees the multilayer network survivability when three links fail simultaneously where each layer suffers a single failure. We present a heuristic approach to reduce the complexity of the problem and present a study based on varying several network parameters to understand their impacts on the protection capacity and the overall network cost. In addition, we present and solve three variations of our original model where we exclude each layer protection in each one of them to compare the cost performance of all models. We observe that generally the DWDM layer protection is the most expensive capacity component. The IP/MPLS layer protection becomes more expensive only when the IP/MPLS unit cost is high. (C) 2012 Elsevier B.V. All rights reserved.