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

Recent advances in WDM technology are now beginning to shift the focus more toward optical networking and network-level issues. Providing survivabilit y at the optical layer is inherently attractive, but whether it makes pract ical sense, given similar mechanisms that are already available at the high er layers, poses serious challenges and raises many questions. Today's core network architecture model has functional overlap among its layers, contai ns outdated functionality, and is too slow to scale. If IP can be mapped di rectly onto the WDM layer, some of the unnecessary network layers can be el iminated, opening up new possibilities for developing a simple and integrat ed protection/restoration scheme that can be coordinated at both the IP and WDM layers. This article presents an overview of existing optical protecti on/restoration schemes. Then we present a novel mesh-based hybrid optical p rotection scheme that utilizes multifiber physical links along with hierarc hical OXC structure. An overview of the envisioned IP-centric DWDM-based op tical data network architecture is then presented. The basis of how to impl ement 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 t he IP and WDM layers.