An Absolute QoS Framework for Loss Guarantees in Optical Burst-Switched Networks

In order to meet the requirements of real-time applications, Optical Burst Switched backbone networks need to provide quantitative edge-to-edge loss guarantees to traffic flows. For this purpose, there have been several proposals based on the relative differentiation quality of service (QoS) model. However, this model has an inherent difficulty in communicating information about internal network states to the edge in a timely manner for making admission control decisions. In this paper, we propose an absolute QoS framework to overcome this difficulty. The key idea is to offer quantitative loss guarantees at each hop using a differentiation mechanism and an admission control mechanism. The edge-to-edge loss requirement is then translated into a series of small per-node loss probabilities that are allocated to the intermediate core nodes. The framework includes a preemptive differentiation scheme, a node-based admission control scheme and an edge-to-edge reservation scheme. The schemes are analyzed and evaluated through simulation. It is shown that the framework can effectively offer quantitative edge-to-edge loss guarantees under various traffic conditions.