Patent ID: 7616567
Filing Date: 2009-11-10
Classification: H04L

Abstract:
1. A shaping apparatus comprising: an output line interface connected to an output line; a plurality of flow control units each for buffering variable length frames belonging to an individual flow and determining a timing to output each of the buffered frames in accordance with a maximum allowed bandwidth and a minimum guaranteed bandwidth having been preset; a read control unit connected to said plurality of flow control units; and a frame distribution unit for discriminating flows to which variable length frames to be output to said output line belong and selectively distributing each of the variable length frames to any of said flow control units allocated for the flow, each of said flow control units comprising: a first frame output timing determination unit which issues a first frame output request for a maximum allowed bandwidth to said read control unit at a frame output timing determined based on the maximum allowed bandwidth preset for each flow; a second frame output timing determination unit which determines a frame output timing based on the minimum guaranteed bandwidth preset per flow, and issues a second frame output request for a minimum guaranteed bandwidth to said read control unit, when the first frame output request for the maximum allowed bandwidth frame is being issued from said first frame output timing determination unit; and a frame output controller for outputting one variable length frame to said output line interface in response to output permission received from said read control unit, wherein: said first frame output timing determination unit has a first leaky bucket based counter structure which decrements a level count value at a decrescent rate in proportion to the maximum allowed bandwidth preset for each flow, each time one of said buffered frames is output by said frame output controller, raises the level count value in accordance with the length of the output frame, and compares the level count value with a first threshold value to determine said frame output timing, said second frame output timing determination unit has a second leaky bucket based counter structure which decrements a level count value at a decrescent rate in proportion to the minimum guaranteed bandwidth present for each flow, each time one of said buffered frames is output by said frame output controller, raises the level count value in accordance with the length of the output frame, and compares the level count value with a second threshold value to determine said frame output timing, and said read control unit grants said output permission to one of said flow control units selected by a predetermined algorithm out of flow control units each of which is issuing the first or the second frame output request.