Hardware implementation of fair queuing algorithms for asynchronous transfer mode networks

Providing quality-of-service guarantees in both cell- and packet-based networks requires the use of a scheduling algorithm in the switches and network interfaces. These algorithms need to be implemented in hardware in a high-speed switch. The authors present a number of approaches to implement scheduling algorithms in hardware. They begin by presenting a general methodology for the design of timestamp-based fair queuing algorithms that provide the same bounds on end-to-end delay and fairness as those of weighted fair queuing, yet have efficient hardware implementations. Based on this general methodology, the authors describe two specific algorithms, frame-based fair queuing and starting potential-based fair queuing, and discuss illustrative implementations in hardware. These algorithms may be used in both cell switches and packet switches with variable-size packets. A methodology for combining a traffic shaper with this class of fair queuing schedulers is also presented for use in network interface devices, such as an ATM segmentation and reassembly device.