Abstract-Recent natural disasters have revealed that emergency networks presently cannot disseminate the necessary disaster information, making it difficult to deploy and coordinate relief operations. These disasters have reinforced the knowledge that telecommunication networks constitute a critical infrastructure of our society, and the urgency in establishing protection mechanisms against disaster-based disruptions.Hence, it is important to have emergency networks able to maintain sustainable communication in disaster areas. Moreover, the network architecture should be designed so that network connectivity is maintained among nodes outside of the impacted area, while ensuring that services for costumers not in the affected area suffer minimal impact.As a first step towards achieving disaster resilience, the RE-CODIS project was formed, and its Working Group 1 members conducted a comprehensive literature survey on "strategies for communication networks to protect against large-scale natural disasters," which is summarized in this article.Index Terms-vulnerability, end-to-end resilience, natural disasters, disaster-based disruptions.

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.

The problem of how to provide, in a cost efficient manner, high levels of availability and service differentiation in communication networks was investigated in [1-3]. The strategy adopted was to embed in the physical layer topology a high availability set of links and nodes (termed the spine). The spine enables through protection, routing and cross layer mapping, the provisioning of differentiated classes of resilience with varying levels of endto-end availability. Here we present an optimization model formulation of the spine design problem, considering link availability and the cost of upgrading link availability. The design problem seeks to minimize the cost while attaining a desired target flow availability. Extensive numerical results illustrate the benefits of modifying the availability of a subset of links of the network to implement quality of resilience classes.