| 摘要 |
PCT No. PCT/JP90/01556 Sec. 371 Date Jul. 29, 1991 Sec. 102(e) Date Jul. 29, 1991 PCT Filed Nov. 29, 1990 PCT Pub. No. WO91/08632 PCT Pub. Date Jun. 13, 1991.The present invention relates to a system switching system in an exchange system in which an ATM switch for exchanging asynchronous transfer mode (ATM) cells is duplexed. In order to switch between ATM switches accurately with drop-out and overlap of cells eliminated, at the input side of the ATM switches, a bit indicating active is inserted into the header of a cell from a transmission line for application to the switch in the active system and a bit indicating standby is inserted into the header of a cell for application to the switch in the standby system and, at the output side of the ATM switches, bits in the headers of cells output from respective switches are referred to and only active indicating cells are selected to be output to a transmission line. Buffers for storing active indicating cells are provided at the outputs of the ATM switches, respectively. At the time of switching between systems, cell input to the old active system is stopped, active indicating cells are stored in the buffer in the active system, and active indicating cells stored in the buffer in the new active system are output after all the active indicating cells in the old active system have been output. |
