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Towards realistic physical topology models for Internet backbone networks

In this paper 1, we consider the problem of physical topology design (i.e., physical connectivity) for Internet backbone networks. We explore the driving forces for service providers to layout fiber links, and propose a new problem formulation that can accurately emulate the existing optical backbone networks. Unlike previous studies which mainly focused on deployment cost, our model captures the physical design principles including (1) the cost of the infrastructure, (2) the expected performance, (3) geographical constraints, and (4) the resilience of the network to link/node failures (survivability). Obtaining an optimal solution is shown to be NP-hard, we thus present a polynomial time heuristic algorithm, HINT, to determine the number and the choice of constituent links. The efficacy of HINT is established in comparison with the published maps of three major scientific and commercial backbone networks: Internet2 Abilene, AT&T domestic express backbone, and Level3 network. Preliminary results reveal that taking performance, resilience and geographical constraints into consideration is necessary to emulate real backbones. The HINT heuristic yields a similarity of more than 90% with the published structures.