| 摘要 |
<p>PURPOSE:To prevent the degradation in quality by abandoning a packet in the case of the packet flow rate exceeding a second threshold larger than a first threshold and taking marked packets as the abandonment object at the time of the occurrence of congestion in a network to adjust the quantity of packets. CONSTITUTION:A terminal abnormality occurrence frequency observing circuit 105 observes the frequency in occurrence of terminal abnormality based on the abnormality detection signals from a terminal abnormality detecting circuit 104. If the frequency is high, a terminal abnormality reporting circuit 106 reports the occurrence and the place of abnormality to a control system. A subscriber control circuit 108 abandons all of the input cell, which is judged to be abnormal, and following cells which have the same logical channel number as this input cell. It is discriminated whether the packet inputted from an output line to a priority control circuit 41 is a marked cell or not by a priority discriminating circuit 111. If the idle space of a buffer 112 is reduced to a pre-scribed value or smaller, an abandonment rate control circuit 113 judges the occurrence of the congestion state and does not store marked cells in the buffer but abandons them to prevent many cell from being sent to the network.</p> |
