Retrospective Pricing Models for Internet Services: Solving the Flat Rate Dilemma "à la Flensburg

The question of how to provide Quality of Service (QoS) has turned out to be of central importance for designing the Internet services of the future and is intimately linked with the problem of how to charge for QoS. Technically, the Differentiated Services (DiffServ) architecture for Internet backbones offers a suitable technology support, whereas appropriate and technically feasible pricing schemes provide an incentive for customers to choose efficiently among these various service classes. This paper is devoted to recent developments in this area, focussing on retrospective aspects of some currently rather popular pricing schemes. Especially the Cumulus Pricing Scheme (CPS) is investigated in great detail, with a focus on deriving numerical parameter val- ues for thresholds and prices of the various service classes as part of the Service Level Agreements (SLA) between providers and customers. Moreover, a CPS-specific simu- lation tool is introduced, and various simulation results supplement the evaluation of this promising new Internet pricing scheme.