Synchronous fine-adjustable rate control circuit for Ethernet congestion management

Rate control mechanism is the necessary part of the Ethernet congestion management. Based on the modified token bucket algorithm, the design of a synchronous rate control circuit that is able to process the variable length frames without knowing their lengths is presented. The main part of the circuit is a large virtual token counter, which is 1024 times the token number, the key feature being that the rate reduction is fine-adjustable.