Scheduling and admission control for integrated-services networks: the Priority Token Bank

This paper proposes a new mechanism called the Priority Token Bank for admission control, scheduling and policing in integrated-services networks. In such networks, both arrival processes and performance objectives can vary greatly from one packet stream to another. There are two principal components to the Priority Token Bank: accepting or rejecting requests to admit entire packet streams, where acceptance means guaranteeing that the packet stream's performance objectives will be met, and scheduling the transmission of packets such that performance objectives are met, even under heavy loads. To the extent possible, the performance of traffic is also optimized beyond the requirements. The performance achieved with the Priority Token Bank is compared to that of other typical algorithms. It is shown that, when operating under the constraint that the performance objectives of applications such as packet voice, video and bulk data transfer must be met in an ATM network, the mean delay experienced by other traffic is much better with the Priority Token Bank. Furthermore, the admission control algorithm can guarantee requirements will be met, and admit more traffic than the common alternatives.