Abstract
Telecommunications networks need to guarantee that all node pairs involved in critical service communications are highly available. Here we adopt a novel approach to the problem of how to provide high levels of availability in an efficient manner. The basic idea is to embed at the physical layer a high availability set of links and nodes (termed the spine) in the network topology to support protection and routing in providing end-to-end availability. We first explore the spine concept through simple topologies illustrating the potential benefits of the approach in improving the overall network availability and the capability to support quality of resilience classes. Then, we study how the structural properties of a network topology can be used to determine heuristics to select a suitable spine and compare this with the case where all network components have the same availability. This is followed by a numerical based study comparing the heuristics with all possible spanning tree based spines for sample topologies. Our results demonstrate how to best design a physical network to support protection methods in achieving high levels of availability efficiently.