| 摘要 |
PURPOSE:To cause a packet exchanging station to discriminate a fault whether it occurs in a line or packet multiplexer upon receiving a health check answer by communicating health check instructing signals and health check answering signals after setting time information to the signals. CONSTITUTION:The packet exchanging station 10 periodically transmits health check instructing signals 100 to the packet multiplexer 20. The multiplexer 20, when operating normally, corrects its own soft timer 400 so that the time of the timer 400 coincides with the time 11 set by the exchanging station 10 from the correction instructing signal 22 of the signals 100 and sends an answer signal 101 to the packet exchanging station 10 after setting the corrected time to the signal 101. On the exchanging station 10 side, the clock information 33 of an answer signal 103 to an instructing signal 300 is confirmed, and when the clock information 33 is cleared, it is recognized that a fault occurs in the packet multiplexer 20. When no answer signal is returned even though the clock information of the answer signal 103 is not cleared, it can be recognized that the packet multiplexer operates normally, but a fault occurs in a line.
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