Flow splitting for end-to-end proportional QoS in OBS networks

In this paper, we propose probabilistic splitting of a packet stream at the edge routers as the basic method to provide end-to-end proportional QoS to packet flows carried through an OBS network, in terms of loss probability. We argue that the only requirement that the optical transport infrastructure has to satisfy is the support for two internal burst classes with wide separation between their respective service levels. Under this condition, we show how quantifiable end-to-end per-flow guarantees can be attained without diminishing network resource usage. The scheme is analyzed theoretically and evaluated through numerical simulations, both in regular topologies (ring networks) and in a mesh network. Our results suggest that a layered approach to the problem of end-to-end QoS provisioning can be very effective when a proportional service model is offered, and that the research on sophisticated scheduling algorithms at the optical switches could be too narrow-focused for that purpose.