Evaluation of Bandwidth Assurance Service Using Red for Internet Service Diierentiation

In best-eeort Internet, Random Early Detection (RED))11] active queue management is accepted as a signiicant improvement over traditional Drop Tail queueing in preventing congestion and reducing other pathological conditions. With initial eeorts for Diierentiated Services In-ternet beginning, RED is naturally regarded as one of the building block mechanisms on which various services can be built. In this paper, we investigate RED's capability to render end-to-end rate guarantee to subscribers , as proposed in 6]. Earlier simulation results for an ideal but unrealistic settingg5] show that RED in combination with edge traac conditioning can be used to provide end-to-end bandwidth guarantee. This paper further explores the idea under diicult and more realistic conditions using extensive simulation. In particular, we report three important ndings. First, TCP throughput assured by the service framework is almost immune to the eeect of round-trip time variation and of multiple congested links. Second, the throughput of adaptive protocols like TCP is protected under the attack of non-adaptive traac (while service assurance for non-adaptive traac is trivially met). Third, the above two properties hold with mostly short-lived, Web-like traac that composes signiicant portion of today's Internet traac. We then discuss the implications of the ndings to Internet Service Providers who plan to ooer predictable bandwidth service. Also, we discuss open issues and future work for bandwidth assurance service.