Coordinated Survivability in IP-over-Optical Networks with IP-Layer Dual-Homing and Optical-Layer Protection

Dual homing is a fault-tolerance mechanism generally used in IP-based access networks to increase the survivability of the network. In a dual-homing architecture, a host is connected to two different access routers; therefore, it is unlikely that the host will be denied access to the network as the result of a failure in the access network, a failure of the access router, or congestion at the access router. However, dual homing cannot provide survivability with respect to possible failures in the optical core network. To provide survivability in the core network, optical protection and restoration techniques must be used. In the past, dual homing architectures and optical protection schemes have been studied independently of one another. This paper studies coordinated multi-layer survivability techniques that use both dual-homing schemes and optical protection schemes in an IP-based access network over a WDM-based optical core network. Specifically, we investigate the protection design problem in the WDM core network, given that a dual-homing infrastructure is implemented in the access network. Several solutions are proposed, and it is shown that the proposed coordinated survivability schemes can reduce cost compared to the case in which the survivability mechanisms are not coordinated between the IP layer and the optical layer.