| 摘要 |
<p>PROBLEM TO BE SOLVED: To avoid the congestion of FRM cell transmission violation by monitoring the appearance cycle of an FRM cell to appear in an input cell stream and abandoning a user cell, which is inputted after this period, until the next appearance when the next cell does not appear within a prescribed discrimination period from the appearance of cell. SOLUTION: When an output q1 of a comparator 11C7 is '0' in which any abnormality occurs in the insertion cycle of forward FRM cells and the forward FRM cells are not detected even after the lapse of a prescribed insertion cycle from the last cell detection, a selector 11C5 selects an input value b0 and resets a reception count number BUC. Since an output q2 of a comparator 11C8 is '1', on the other hand, a selector 11C6 selects an input (c) and updates the number of times of abnormality in insertion interval of a memory 11C1 to '1'. After updating, the output q1 of the comparator 11C7 is returned to '1≈and it is continued while no cell is detected. When this period of no detection becomes a threshold value for discrimination, the outputs q1 and q2 of the comparators 11C7 and 11C8 are turned to '0' and the discriminated result of a discriminator 11C9 is switched into violation so that a cell processing part stops passing user cells and abandons them.</p> |
