Network Hierarchy and Multilayer Survivability

This document is the deliverable out of the Network Hierarchy and Survivability Techniques Design Team established within the Traffic Engineering Working Group. This team collected and documented current and near term requirements for survivability and hierarchy in service provider environments. For clarity, an expanded set of definitions is included. The team determined that there appears to be a need to define a small set of interoperable survivability approaches in packet and non-packet networks. Suggested approaches include path-based as well as one that repairs connections in proximity to the network fault. They operate primarily at a single network layer. For hierarchy, there did not appear to be a driving near-term need for work on 'vertical hierarchy,' defined as communication between network layers such as TDM/optical and MPLS. In particular, instead of direct exchange of signaling and routing between vertical layers, some looser form of coordination and communication, such as the specification of hold-off timers, is a nearer term need. For 'horizontal hierarchy' in data networks, there are several pressing needs. The requirement is to be able to set up many LSPs in a service provider network with hierarchical IGP. This is necessary to support layer 2 and layer 3 VPN services that require edge-to- edge signaling across a core network. Please send comments to [email protected]