Enhancing Availability for Critical Services

Abstract

Traditional approaches to provide classes of resilient service take the physical network availability as an input and then deploy redundancy and restoration techniques at various layers, often without full knowledge of mappings between layers. This makes it hard (and often inefficient ) to ensure the high availability required by critical services which are typically a small fraction of the total tra c. Here, the innovative technique of embedding a higher availability sub-structure, designated the spine, into the network at the physical layer, is explored. In the spine-based approach, it is considered that high availability must begin at the physical level, and then must be reinforced in upper layers. A recent disaster resilience framework, named FRAmework for DIsaster Resilience, which incorporates reliable network design (i.e., using the spine), disaster failure modelling and protection routing to improve the availability of critical services is discussed. Next, a proposal to select network links for availability upgrade to ensure high availability is presented. This is followed by a study assuming that if disaster-prone areas are known, they can be represented as obstacles which should be avoided when deploying the physical backbone of a communications network. Hence, a heuristic for a minimum cost Euclidean Steiner tree taking into account the presence of soft obstacles is presented.