Theories and Models for Internet Quality of Service

We survey recent advances in theories and models for Internet Quality of Service (QoS). We start with the theory of network calculus, which lays the foundation for support of deterministic performance guarantees in networks, and illustrate its applications to integrated services, differentiated services, and streaming media playback delays. We also present mechanisms and architecture for scalable support of guaranteed services in the Internet, based on the concept of a stateless core. Methods for scalable control operations are also briefly discussed. We then turn our attention to statistical performance guarantees, and describe several new probabilistic results that can be used for a statistical dimensioning of differentiated services. Lastly, we review recent proposals and results in supporting performance guarantees in a best effort context. These include models for elastic throughput guarantees based on TCP performance modeling, techniques for some quality of service differentiation without access control, and methods that allow an application to control the performance it receives, in the absence of network support

Efficient admission control of piecewise linear traffic envelopes at EDF schedulers

In this paper, we present algorithms for flow admission control at an earliest deadline first link scheduler when the flows are characterized by piecewise linear traffic envelopes. We show that the algorithms have very low computational complexity and, thus, practical applicability. The complexity can be further decreased by introducing the notion of discretized admission control. Through discretization, the range of positions for the end points of linear segments of the traffic envelopes is restricted to a finite set. Simulation experiments show that discretized admission control can lend to two orders of magnitude decrease in the amount of computation needed to make admission control decisions over that incurred when using exact (nondiscrete) admission control, with the additional benefit that this amount of computation no longer depends on the number of flows. We examine the relative performance degradation (in terms of the number of flows admitted) incurred by the discretization and find that it is small