Convergence of Protection and Restoration in Telecommunication Networks

This paper argues for the need for convergence of protection and restoration schemes in today's telecommunication networks. Such networks are presented both in a layered context and from an end-to-end perspective. Such convergence is both necessary to ensure inter-working amongst a multitude of technologies deployed and desirable to ensure simplified operations. This paper further identifies the issues and inter-working items that need resolution in today's telecommunication and data networks in order to achieve inter working amongst various existing and emerging restoration and protection schemes in a layered and end-to-end context. End-to-end context covers the access, metro, and long haul dimensions of the network. It also encompasses both the services and the transport layers of the network in the context of multi-domain, multi service provider networks. Layering issues arise from the mix of technologies at several layers for example: optical transmission and CWDM/DWDM at physical layer, SONET/SDH framing and management at layer-1, ATM, MPLS, Ethernet, and resilient packet rings at layer-2, and finally IP and routing protocols at layer-3. Given that some degree of routing and signaling intelligence is migrating down to the optical layer equipment, this whole layering concept is currently in transition. This paper shows the need for convergence in the form of a two level protection and restoration scheme. A service independent layer and a mesh restoration capability at the routing layer.