Supporting a low delay best-effort class in the presence of real-time traffic

In this paper we propose a packet scheduler to provide a low delay service to best-effort packets without jeopardizing the delay bounds associated with real-time flows. We show that some of the well known service mechanisms for integrating soft real-time tasks into a hard real-time environment, such as the total bandwidth server of Spuri and Buttazzo (1996), turn out to be special cases of our scheme. Our experiments with realistic traffic, consisting of a mix of real-time flows such as voice and video and several best-effort flows show an average improvement of up to 45% in the delay experienced by the best-effort flows, without any real-time flows missing their deadlines.