A new scheduling mechanism to provide relative differentiation for real-time IP traffic

Design alternatives for supporting real-time traffic in a differentiated services IP network node are studied. A scheduling algorithm called weighted earliest due date (WEDD) is proposed that provides tunable delay differentiation for applications like video or voice over IP. WEDD enhances the earliest due date (EDD) scheduling mechanism in such a way that not only different delay bounds but also different deadline violation probabilities are provided. The ratios of violation probabilities in different classes are easily specified by a set of parameters. Simulation studies are performed to show that the scheduler is able to maintain the specified ratios under various traffic conditions in short as well as in long time scales.