On joint protection/restoration in IP-centric DWDM-based optical transport networks

Previous advances in WDM technology are now beginning to shift the focus more toward optical networking and network-level issues. Providing survivability at the optical layer is inherently attractive, but whether it makes practical sense, given similar mechanisms that are already available at the higher layers, poses serious challenges and raises many questions. Today's core network architecture model has functional overlap among its layers, contains outdated functionality, and is too slow to scale. If IP can be mapped directly onto the WDM layer, some of the unnecessary network layers can be eliminated, opening up new possibilities for developing a simple and integrated-protection/restoration scheme that can be coordinated at both the IP and WDM layers. This article presents an overview of existing optical protection/restoration schemes. Then we present a novel mesh-based hybrid optical protection scheme that utilizes multifiber physical links along with a hierarchical OXC structure. An overview of the envisioned IP-centric DWDM-based optical data network architecture is then presented. The basis of how to implement a more direct IP standard-based approach for closer and efficient IP-WDM integration is also discussed. Finally, we articulate a view of how to provide a joint protection/restoration scheme that is coordinated at both the IP and WDM layers.