Credit-based fair queueing (CBFQ): a simple and feasible scheduling algorithm for packet networks

A simple rate-based scheduling algorithm for packet-switched networks (e.g. Internet, ATM) is proposed. By using simple counters to keep trade of the amount of credits accumulated by each traffic stream, the algorithm decides which stream to serve next based on the bandwidth share allocated to each traffic stream and the sizes of their respective head of line (HOL) packets. Our proposed CBFQ algorithm achieves the same fairness and delay bounds as the alternative approaches based on virtual time, while avoiding the implementation problems inherent in these methods. In addition, to take advantage of the fixed packet size in ATM networks, a variant of the algorithm (CBFQ-F) is proposed. By relaxing the fairness bound by a negligible amount, CBFQ-F achieves a complexity of O(1).