Comparison of quasi-regular composite-star and multi-hop structures for core networks

A novel composite-star architecture, nicknamed the Petaweb, has been recently proposed for high capacity optical core networks. Its topologic structure is such that electronic edge nodes are always connected to each other through a single core switch, and that the core switches are disconnected. The aim is to simplify the traffic engineering and the upgradeability of core networks. In its regular form, this architecture suffers from high fiber cost and low utilization. A recent work tackles the problem of directly designing a quasi-regular composite-star structure, showing that the network cost can get more than halved and that the resources utilization can be significantly improved. In this paper, we compare the quasi-regular composite-star structure to classical irregular multi-hop structures. We show that increasing the weight of a propagation delay virtual cost in the design dimensioning objective function, multi-hop core networks tend to assume a quasi-regular composite-star like topologic structure, with a few core fibers. This suggests that such an architecture is the natural solution whether length-dependent additive costs are considered as part of the design dimensioning objective.