Weighted fair queuing approximation in a network switch using weighted round robin and token bucket filter

Abstract

An integrated network switch having multiple network switch ports for outputting data frames also includes a dequeuing system for selectively supplying a data frame for output according to a specified priority by an output switch port. The dequeuing system includes, for each network switch port, a plurality of priority queues configured for holding assigned data frames based on respective priorities assigned by switching logic. A weighted round robin scheduler supplies the assigned data frames held in the priority queues to the output switch port according to a prescribed weighted round robin scheduling. In addition, the dequeuing system uses token bucket filters for selectively passing the assigned data frames to the respective priority queues in a manner that ensures that a given data frame having a large size does not interfere with bandwidth reserved for high-priority packets requiring guaranteed quality of service. Each token bucket filter selectively passes the corresponding assigned data frame to the corresponding priority queue based on a determined availability of at least a required number of tokens corresponding to a determined size of the corresponding assigned data frame. If the token bucket filter determines an insufficient number of tokens are available relative to the required number of tokens, the token bucket filter either drops the frame or shifts the frame to a lower priority queue. Hence, weighted fair queuing can be approximated using weighted round robin scheduling without interference by large-sized data packets.