Cost effectiveness of joint multilayer protection in packet-over-optical networks

The recent advances in generalized multiprotocol label switching/multiprotocol label switching (GMPLS/MPLS) and extensive study and understanding of packet-over-optical network architecture have made it possible to manage the resources of the packet network and underlying optical transport network in an interoperable manner. This opens up the possibility for coordinated actions across the two networking layers. In this context, we propose and evaluate a novel joint protection scheme for future packet-over-optical networks. There are two aspects that make the proposed joint scheme novel and, furthermore, cost effective: 1) It captures the best tradeoff between the finer grooming granularity of the packet layer and the cheaper port cost of the optical layer, and 2) it reuses network resources from both the primary paths and paths that exist for link failure protection by the optical layer. To examine the proposed approach, a mixed-integer optimization model was developed. In particular, we observe that overlaying joint packet-optical router protection with transport-layer link protection permits strong synergy of protection capacity reuse. Indeed, our case studies show that the proposed joint packet-optical router protection is low- or no-cost when it is overlaid on an existing transport-layer protection scheme.