Policy-based Restoration in IP/Optical Transport Networks

Restoration in transport networks is typically facilitated using reactive techniques at different layers, namely optical and IP restoration [1]. Optical restoration involves re-routing an existing optical connection (i.e., a lightpath) around a failure (e.g. link, amplifier, switch and transponder failures) in the optical layer. This strategy is efficient in terms of resource utilization, as backup resources are reserved dynamically after the failure and therefore are not blocked during normal operation. However, equipment reconfiguration and power equalization processes in the optical domain are relatively slow (order of seconds), and are thus not suitable for time critical services.