March 16, 2015

Notice on TN11PIU Wrongly Reported THUNDERALM Alarm on OptiX OSN 6800

Summary:
When the TN52SCC board is used on OptiX OSN 6800, the power module of the TN11PIU board interferes with lightning protection alarm signals. As a result, a detection error occurs and the THUNDERALM alarm is wrongly reported.

OSN 6800

[Problem Description]
Trigger condition:
The TN52SCC board is used on DWDM Huawei OptiX OSN 6800 and the fan tray assembly is running at high speed.

Symptom:
When the TN52SCC board is used on OptiX OSN 6800 and the fan tray assembly is running at high speed, the TN11PIU board reports a THUNDERALM alarm.

Identification method:
When the OptiX OSN 6800 uses the TN52SCC board, identify the problem as follows:
1. Set the fan tray assembly to low speed. The THUNDERALM alarm is cleared 10 seconds later.
2. Set the high speed again. The alarm is reported 10 seconds later.
If the preceding symptoms occur, the alarm is wrongly reported and the TN11PIU board is involved in the problem.
Note: After the above identification operations are completed, you must restore the fan try assembly speed to prevent impact on NE heat dissipation.

[Root Cause]
The power module of the TN11PIU board supplies power to the fan tray assembly. If the fan tray assembly is running at high speed, the load current of the power module is great and the power module noise is increased accordingly, interfering with lightning protection signals. If at this time the TN52SCC board is used, it detects lightning protection signals at a high frequency. Therefore a detection error occurs and the THUNDERALM alarm results. If the TN51SCC board is used, it detects the signals at a low frequency and therefore no detection error or related alarm results. If the fan tray assembly is running at low speed, the load current of the power module is small and therefore the power module noise is small. Therefore, no detection error or related alarm results.

[Impact and Risk]
If an error occurs in detecting the lightning protection signals, the THUNDERALM alarm will be wrongly reported by the TN11PIU board but services are not affected.

[Measures and Solutions]
Recovery measures:
None.
Workarounds:
None.
Preventive measures:
Not available currently. If any preventive measure is available, the notice will be updated.
Material handling after replacement:
None.

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