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Enhancing Class-Based Service Architectures with Adaptive Rate Allocation and Dropping Mechanisms

Nicolas, Christin; Liebeherr, Jorg; Abdelzaher, Tarek
Nicolas, Christin
Liebeherr, Jorg
Abdelzaher, Tarek
Class-based service differentiation can be realized without resource reservation, admission control and traffic policing. However, the resulting service guarantees are only relative, in the sense that guar- antees given to a flow class at any time are expressed with reference to the service given to other flow classes. While it is, in principle, not feasible to provision for absolute guarantees (i.e., to assure lower bounds on service metrics at all times) without admission control and/or traffic policing, we will show in this paper that such a service can be reasonably well emulated using adaptive rate allocation and drop- ping mechanisms at the link schedulers of routers. We name the resulting type of guarantees best-effort bounds. We propose mechanisms for link schedulers of routers that achieve these and other guarantees by adjusting the drop rates and the service rate allocations of traffic classes to current load conditions. The mechanisms are rooted in control theory and employ adaptive feedback loops. We demonstrate that these mechanisms can realize many recently proposed approaches to class-based service differentiation. The effectiveness of the proposed mechanisms are evaluated in simulation experiments as well as in mea- surement experiments of a kernel-level implementation on FreeBSD PC-routers with multiple 100 Mbps Ethernet interfaces.
University of Virginia, Department of Computer Science, 2004
Published Date
Libra Open Repository
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