Programmable rate-based scheduler (PRS) for ATM switches and multiplexers

We consider the Virtual Clock Scheduling (VCS) algorithm and propose a Time-Priority Model (TPM) for illustrating the algorithm. We show that TPM can represent many time-dependent priority schemes such as FCFS, LCFS, RR, EDF and VGS. Based on TPM, we derive an enhanced virtual clock scheme, Gated Virtual Clock Scheduling (GVCS), which gives the same throughput and delivery guarantee as VCS, but gives a smaller delay for low-rate streams. We consider the implementation of TPM and propose a Programmable Rate-based Scheduler (PRS) which can be programmed at any time to change its configuration or discipline.