Dynamic quality of service control in packet switch scheduling

Recent research in packet switch scheduling algorithms has moved beyond throughput maximization to quality of service (QoS) control. Several classes of algorithms have been shown to achieve maximal throughput under certain system conditions. Between classes and within each class, QoS performance varies based on arrival traffic and properties of the scheduling algorithm being utilized. Here we compare two classes of throughput-maximizing algorithms and their performance with respect to buffer sizes. These classes are randomized algorithms, which can be characterized as offline algorithms, and projective cone scheduling algorithms, which are online since they respond to the current workload in the system. In each class, parameters can be fine-tuned to reflect the priorities of individual switch ports. We show how the online algorithms lead to significantly better quality of service performance.