Patent ID: 8737227

Claim:
A packet transmission device comprising: a buffer that includes queues and that stores packet data in any of the queues; a queue manager that outputs queue-status signals, each indicating whether transmittable packet data exists in one of the queues corresponding with the buffer; a bandwidth controller that accumulates tokens for each queue at a certain period and that outputs token-status signals for respective queues, each token-status signal indicating whether an amount of the tokens accumulated for a corresponding queue is larger than a token threshold associated with the corresponding queue; a queue selector that preferentially selects a queue whose duration time of a transmittable state, in which the corresponding queue status signal indicates that transmittable packet data exists in the corresponding queue and the corresponding token-status signal indicates that the amount of the accumulated tokens is larger than the token threshold associated with the corresponding queue, is greater than a duration-time threshold associated with the corresponding queue; and a buffer reader that controls reading of the packet data from the selected queue.