Robustness in multilayer optical communication Networks

 

ROSA BENITO

UNIVERSIDAD POLITÉCNICA DE MADRID

 

In this communication we present an empirical study of the SDH telecommunication network operated by Telefónica in Spain. SDH (Synchronous Digital Hierarchy) networks transport different traffic types, such as voice, video, multimedia, and data packets (as those generated by IP) over the same fiber wire. SDH networks are end-to-end circuits strictly designed as ring, mesh, bus and other motifs connecting equipments with different link capacities. From a hierarchical point of view the SDH network of Telefónica España is divided into four layers with different topologies. Our results showed emergent complexity in all the Spanish provincial networks analyzed, despite being largely dependent on strict planning policies [1,2]. Particularly, we found power-law scaling in the degree distribution and properties of small-world networks, signs of self-organization in the evolution of complex systems. These complex topological properties have been related to the robustness of systems. Under this perspective, in this work we also present a study of the robustness of the Spanish SDH network by the simulation of direct attacks to those equipments that control the flow of information. We have found that the robustness depends not only on the connectivity of equipments but also on the capacity and type of links associated to those equipments. Consequently we have also observed that the robustness of SDH networks depends on the particular initial design and evolution of each Spanish province. [1] J. P. Cárdenas, M. L. Mouronte, A. Santiago, V. Feliu and R. M. Benito “Complex topology in optical transport networks”, International Journal of Bifurcation and Chaos. 20(3) 2010. [2] A. Santiago, J. P. Cárdenas, M. L. Mouronte, V. Feliu and R. M. Benito, “Modeling the topology of SDH Networks”. International Journal of Modern Physics C 19 (2008) 1809-1820.