| 摘要 |
PROBLEM TO BE SOLVED: To enable turn back at the subscriber side end of an ATM terminating apparatus by using a loop detection cell as a separation test as the responsibility division point of interface to the ATM subscriber side. SOLUTION: When an ATM terminating apparatus 2 receives an LP2 detection cell (loop detection cell) from a private unit 4 through an electric communication enterpriser 3, a transition is made to a turn back test mode and a test cell is transmitted from the private unit 4 to the ATM terminating apparatus 2. The test cell is turned back at the subscriber side end of the ATM terminating apparatus 2 and when the private unit 4 confirms that the test cell pattern is normal and has no error, an LP2 release cell is transmitted from the private unit 4 to the ATM terminating apparatus 2. When the ATM terminating apparatus 2 receives that LP2 release cell, the turn back test mode is released and normal mode is reset.
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