Establishing the physical survivability of large networks is not a trivial task. Some techniques for assessing physical survivability such as the cutset method can not deal with large size networks [1], [2]. A fast technique for finding biconnected components of a graph and testing the network for node-/link-bridges, presented in [3], does not provide any further information, such as identifying the fundamental cycles within the network, which would significantly benefit the next phase of

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... k design for protection using such techniques as shared backup path protection (SBPP), p-cycle, or ring protection [3]. This paper presents an alternative technique, based on graph theory, for evaluating the physical survivability of networks. This technique can deal with network sizes of many thousand nodes, with computational times which are comparable with the biconnected components method, whilst providing more information about the susceptibility of a network to individual link and node failures in preparation for the next phase of network protection design.