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For the failure of the optical transceiver, it can be divided into permanent fault and intermittent fault. A permanent fault means that the alarm is always maintained; an intermittent fault means that there is no certain time of the fault, and sometimes it can be automatically restored.
For permanent faults, loops can be used at one end, and the other end can be displayed from the switch or layer by layer, using a transport analyzer.
1. If the transmission alarm occurs in pairs, for example RJA (remote alarm) occurs on the A side, then the B side may be LFA (frame out-of-synchronization alarm) or AIS (receive alarm), sometimes both alarms exist; another type is LS ( Signal loss) alarm.
One of the causes of the failure, there is a problem with the signal sent by the DM at the A side, that is the 2Mb/s signal sent is erroneous or interrupted.
Judgment method: Loop back to the A side with the A-side DDF frame. If there is an LS or AIS alarm on the A side, the fault is caused.
Solution: Ask the equipment room personnel to restart or reload the relay module to clear the alarm.
The second reason is that there is a problem with the transmission from the low-order group A to the B-side, causing 2Mb/s signal error or interruption.
Judgment method: If there is a problem between A and B the low-order groups at both side of A and B, the B side displays an AIS or LFA alarm. If the low-order group from the B side is interrupted to the DM signal, the B-side displays the LS alarm.
Solution: According to the detected obstacle points, or re-do the head on the DDF, or replace the U-Link, or replace the disk to achieve the purpose of restoring the circuit.
2. The transmission alarm is not in pairs. For example, AIS, RJA alarm, or LFA alarm occurs at the A side, and there is no alarm at the opposite side. At this time, the call cannot be made (take the S1240 switch as an example).
The reason is that the A-side relay module (DM) is dead. In this case, the DMs at both side need to be reactivated. Doing that may restore the circuit, and the first case may occur. If the first case occurs, proceed as described above.
