Optimizing multi-layered networks towards a transparently optical internet

Abstract

Comparison between alternative technologies for switching and routing is difficult for several reasons: (i) the range of options is quite large and appears to demand knowledge over a very wide range -- wider than we can reasonably expect to find in any one individual; (ii) in addition, each of the alternative technical solutions can potentially be used in combination with one of more of its competitors; (iii) the impact on the traffic being handled is difficult to model, and therefore it is almost inconcievable that we can predict the performance which can be delivered by complex configurations. In this paper we propose and develop a unified framework for multiple technologies that interwork together. To do this we adopt a simple model based on the principle that (i) technologies can be modelled as layers; (ii) traffic can be modelled as a Poisson stream of flows; and (iii) the dynamic (and static) choice between layers can be modelled by a strategy for splitting traffic between layers. Once this unified framework has been adopted, alternative technologies can be incorporated into in this model by choosing a collection of parameters which determine, for each layer, what it will cost to deliver a certain type of traffic and how traffic will be split between layers when there is a choice.