Problem Description

An operator's current network consists of one set of Metro1000V3 devices, one set of Metro1000 devices, and one set of OSN3500 devices to form an SNCP ring. one 2M service is configured from the Metro1000V3 device to the OSN3500 device, and the E1_LOC alarm is reported on the 2M port of the PQ1 board of the Metro1000V3 device, and the corresponding time slot of the OSN3500 device reports TU_AIS, and there is no alarm at the pass-through station. The corresponding time slot of the OSN3500 device reports TU_AIS, and there is no alarm at the pass-through station.

Alarm information

E1_LOC, TU_AIS

Processing

The alarm does not disappear after replacing the PQ1 veneer. After communicating with the customer, we understand that the customer-side device is a Cisco router with a hard ring on the DDF shelf, and the customer informs us that the corresponding port status of the router is UP. at this point, we can rule out the possibility of hardware failure.

Go to the site to check the grounding of the equipment, found that the Cisco router is located in the cabinet is not grounded, due to the site can not do the ground, the Cisco router will be temporarily moved into the grounded cabinet, at this time the E1_LOC alarm disappeared, the business is normal. After the cabinet is grounded, the service is normal.

Root cause

The TU_AIS alarm was first addressed, and the timing of the alarm suggested that the TU_AIS alarm was generated by the E1_LOC alarm. To determine this idea, after activating the cross de-activation at the pass-through station and hitting the time slot ring on the Metro1000V3 device, the TU_AIS alarm disappeared. Thus, it was determined that the TU_AIS alarm was generated by the E1_LOC alarm. Under normal circumstances , the E1_LOC alarm will not be inserted in all 1s, which means that it will not cause the opposite end station to report the TU_AIS alarm. After consulting with R&D, we know that under version 5.37.05.12 of Metro1000V3, the E1_LOC alarm will be inserted in all 1's. In this case, we need to analyze the E1_LOC alarm. At this point, we have to analyze the reason for E1_LOC, which represents the problem of the clock signal on the receiving client side, and there are several reasons for this:

1, the customer side of the equipment failure leads to send a bad signal.

2, PQ1 single board failure.

3, Poor equipment grounding.

Recommendations and Summary

In general, E1_LOC alarms do not cause TU_AIS alarms, but under certain versions E1_LOC is under-plugging all 1s causing the opposite end to report TU_AIS.

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