The single-queue switch: a building block for switches with programmable scheduling

We introduce a new approach to ATM switching. We propose an ATM switch architecture which uses only a single shift-register-type buffering element to store and queue cells, and within the same (physical) queue, switches the cells by organizing them in logical queues destined for different output lines. The buffer is also a sequencer which allows flexible ordering of the cells in each logical queue to achieve any appropriate scheduling algorithm. This switch is proposed for use as the building block of large-stale multistage ATM switches because of low hardware complexity and flexibility in providing (per-VC) scheduling among the cells. The switch can also be used as scheduler/controller for RAM-based switches. The single-queue switch implements output queueing and performs full buffer sharing. The hardware complexity is low. The number of input and output lines can vary independently without affecting the switch core. The size of the buffering space can be increased simply by cascading the buffering elements.