Managing and pricing service level agreements for differentiated services

Costas Courcoubetis and Vasilios A. Siris
Institute of Computer Science (ICS), FORTH

In Proc. of 7th IEEE/IFIP International Workshop on Quality of Service (IWQoS'99), London, UK, May-June 1999. [pdf, .ps.gz]


We present an approach to manage and price service level agreements (SLAs) for differentiated services that uses a simple upper bound for the effective bandwidth of the conforming traffic as a proxy for resource usage. The bound depends on the user's traffic profile (peak rate and token bucket descriptor). Usage charges for a specific time period are proportional to this proxy, and their calculation requires only measurements of volume. We discuss and present experimental results regarding the incentives and fairness of the proxy, which is required in order to achieve economic efficiency. An important feature of our approach is the simplicity of the user's procedure for selecting optimal token bucket parameters. Our approach is quite generic and can be applied to scheduling disciplines that enable the provision of multiple service classes with different levels of performance. Finally, we present a case study for two service classes, a real-time and a non-real-time service, with actual Internet traces.

Keywords: service level agreement, traffic contract, token bucket, differentiated services, usage-based charges

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