Abstract

SDH (Synchronous Digital Hierarchy) is a strictly planned system. Rings, meshes, stars or tree-branches topologies are designed to connect its basic elements. In spite of that, we have found that the SDH network operated by Telefonica-Espana displays complex traits like other complex networks. In particular we have found power-law scaling in the degree distribution. The scaling observed has a well reported positive effect on the robustness of systems. Using other properties of the networks and nodes, such as centrality, betweenness, clustering and path lengths, we have shown that the designed topology together with the growth of the network also contribute to the robustness of SDH systems.