| 摘要 |
PROBLEM TO BE SOLVED: To provide an ATM(asynchronous transfer mode) switch redundancy switching system for executing non-instantaneous cut swithcing, without the abolishment and overlap of ATM cells in short time, even if input traffic is congested. SOLUTION: When a system switch request is generated, a switch information insertion part 5 sets the switch information bit of the cell to be '1', and the number of cells accumulated in a buffer 9a is set in a counter 11a, when the switch information detection part 7a of a present system detects the cells. A buffer 9b is cleared, when the switch information detection part 7b of a standby system detects the cell whose switch information bit is '1', and reading is stopped. The counter 11a reduces '1' whenever the cell is read from the buffer 9a. When it becomes zero, a switch information re-insertion part 10a sets the switch information bit of the cell which is read at that time to be '1'. The write/read control part 12b of a standby system switch resumes reading from next read cell timing. A selection circuit 13 selects the cell of the standby system switch from the next cell, when a switch information detecting part 14 detects the switch information bit '1' of the output cell in a present system switch.
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