| 摘要 |
<p>PURPOSE:To prevent the inversion of cell arrival order according to alternative cut-back by sending a cell to a bypass route and an ordinary route piror to alternative cut-back processing by the detection of fault recovery, and measuring the transmission delay time of the cell. CONSTITUTION:The transmission delay time is measured by sending a cell for delay measurement to the bypass route and a route in use by a route delay measuring means 12 when a line fault is recovered. The difference of the transmission delay time of both routes is calculated from a measured result by a guard time setting means 13 as guard time, and it is informed to an alternative cut-back processor 11. The processor 11 executes the alternative cut-back based on the above information, however, a timing to deliver a first cell after the cut-back is set after the guard time calculated by the means 13 after sending the last cell to the bypass route elapses. In such a way, it is possible to prevent the passing of the cell passing the bypass route before the execution of the alternative cut-back over the cell passing the route in use after the execution of the cut-back occurring.</p> |
