Computer Sciences Dept.

A SLA Perspective on the Router Buffer Sizing Problem

Joel Sommers, Paul Barford, Albert Greenberg, Walter Willinger

In this paper, we discuss recent work on buffer sizing in the larger context of an ISP's need to offer and guarantee competitive Service Level Agreements (SLAs) to its customers. Since SLAs specify the performance that an ISP guarantees to its customers, they provide critical context for many configuration and provisioning decisions and have specific relevance to buffer sizing. We use a controlled laboratory environment to explore the tradeoffs between buffer size and a set of performance metrics over a range of traffic mixtures for three different router designs. Our empirical study reveals performance profiles that are surprisingly robust to differences in router architecture and traffic mix and suggest a design space within which buffer sizing decisions can be made in practice. We then present a prelimnary approach for making buffer sizing decisions within this design space that relates directly to performance and provisioning requirements in SLAs. By comparing our approach with recent and past work on buffer sizing, we show how these prior studies fit into the broader design space we identify and comment on the potential benefits of active queue management in constraiaed buffer configurations.

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