Capacity Assignment for Proportional QoS in Diffserv-Like Networks

The Differentiated Services (Diffserv) architecture is a scalable solution for providing quality of service (QoS) over packet switched networks. By its very definition, Diffserv is not designed to offer strict performance guarantees to its subscribers, and the actual differentiation between the service classes is currently left as an open design issue. We consider in this paper the notion of relative performance guarantees. Specifically, the goal of the network manager is to maintain predefined ratios between the average delays of the different service classes. For that purpose, the manager judiciously allocates available capacity between the service classes. This scheme is studied within a traffic flow model, with self-optimizing users who can choose their input flow rate to each service class. The entire problem is naturally formulated as a non-cooperative game, where the players are the network manager and the individual users. Concentrating on a single link model with multiple service classes, we demonstrate the existence and uniqueness of the equilibrium, and address the efficient computation of the capacity assignment in equilibrium. We further provide an adaptive capacity adjustment scheme which is applicable when the user model is unknown. We briefly outline extension of our results to a general network topology, and the role of pricing and admission control within the proposed framework