Patent ID: 8000247

Claim:
A bandwidth management apparatus, comprising: a queue management controller to store each arriving packet in one of a plurality of queues according to a destination of the packet; a bandwidth management controller to add tokens corresponding to a bandwidth set value predetermined for each destination, but not exceeding a prescribed upper limit value, at every predetermined interval to each of a plurality of token buckets corresponding to said plurality of queues, and which, when a packet is output from any one of a plurality of said queues, removes tokens corresponding to a packet length of said output packet from the token bucket corresponding to said queue from which said packet is output; and a scheduler operating under a bandwidth management mode and a surplus bandwidth mode, where in said bandwidth management mode said packets are output only when the tokens contained in the token bucket corresponding to any one of the queues sequentially referred to are larger in value than a predetermined threshold value, and in said surplus bandwidth mode when the tokens contained in the token bucket corresponding to every queue in which any packet is stored are not larger in value than the threshold value, said queues are referred to sequentially in a predetermined order and said stored packets are output one by one until a next update interval arrives, and further, in said bandwidth management mode the upper limit value of said tokens to be contained in said token bucket when any packet is stored in any one of said plurality of queues is set higher than the upper limit value when no packets are stored in the any one of queues in which any packet is stored and the threshold value is 0 and the upper limit value of said tokens when any packet is stored in said corresponding queue is set equal to twice or a larger integral multiple of said bandwidth set value, while the upper limit value of said tokens when no packets are stored in said corresponding queue is set equal to said bandwidth, while in said surplus bandwidth mode the upper limit value of said tokens to be contained in said token bucket when any packet is stored in any one of said plurality of queues is set higher than the upper limit value when no packets are stored in the any one of queues in which any packet is stored and said threshold value is 0 and the upper limit value of said tokens when any packet is stored in said corresponding queue is set equal to a value calculated from a number of queues installed in said bandwidth management controller, a time required to output a packet of a longest packet length, and an update interval.