Summary: If the ejector lever on an STG board is not fully inserted during board installation or if a gap is introduced between the front panel and the surface of the board during front panel assembly, the micro switch on the STG board will not be closed and a BD_STATUS alarm will be reported for the STG board.
[Problem Description]
Trigger conditions:
The ejector lever on an STG board is not fully inserted during board installation, or a gap is introduced between the front panel and the surface of the board during front panel assembly.
Symptom:
A BD_STATUS alarm is intermittently or constantly reported for an STG board.
Identification:
You can determine that an STG board has the said problem when all the following conditions are met:
1. A BD_STATUS alarm is reported for the STG board.
2. The STAT indicator on the STG board is steady green.
3. Manufacturer information and logs of the STG board can be retrieved successfully.
[Root Cause]
Function of the micro switch:
The ejector lever and micro switch on an STG board are associated. When the active STG board is removed, the micro switch becomes open. When the board receives the open micro switch signal, the standby STG board takes over to replace the active STG board, ensuring a hitless switchover between the active and standby STG boards.
Root cause for the BD_STATUS
There are following situations in which this problem will occur:
1. The ejector lever is fully inserted, but the micro switch is not closed. In this situation, a stable BD_STATUS alarm is present on the STG board. (Usually this occurs during deployment.)
2. The ejector lever is fully inserted, but the micro switch state is unstable, alternating between closed and open. In this situation, transient BD_STATUS alarms are reported for the STG board.
[Impact and Risk]
The STG board is a clock board and provides a working clock for an NE. For each NE, two STG boards are configured to provide 1+1 backup. Therefore, there are three scenarios:
A. If the active STG board has the said problem, a BD_STATUS alarm is reported for the board and the standby STG board automatically takes over to replace the active STG board. Services on the NE are not affected.
B. If the standby STG board has the said problem, a BD_STATUS alarm is reported for the board. Services on the NE are not affected.
C. If both STG boards on an NE have the said problem, only the standby STG board is set to the offline state. The active STG board is operational and no BD_STATUS alarm is reported for the active STG board. Services are not affected in this situation.
In the preceding situations, there is no impact on services, but a switchover between the active/standby STG boards cannot be triggered. Therefore, in these situations, the defective STG boards must be replaced promptly. For details, see the following Measures and Solutions.
[Measures and Solutions]
Recovery measures:
None.
Workarounds:
Caution: Apply for a maintenance window for taking the following workaround.
Disable the micro switch function for defective STG boards by running commands in the script provided together with this precaution notice. The script file name is Micro Switch Function Disable Script for the OSN 8800 STG Boards.
For details, see the Guide to Disable the Micro Switch Function for the OptiX OSN 8800 STG Boards.
Note：
The micro switch enable commands are non-retainable; instead they will be lost after the STG boards are reseated or undergo a warm/cold reset. In this situation, the commands must be issued again.
The commands vary with product versions. Currently, the commands support only mainstream versions: V100R004C04SPC800, V100R006C01SPC200, V100R006C01SPC300, and V100R006C01SPC500. For any other Huawei product version, independently upgrade the STG board software and logic, or contact Huawei R&D engineers to perform the upgrade.
The workaround may introduce the following risk:
When two STG boards are deployed for 1+1 backup on an NE, services on the NE are occasionally interrupted after the active STG board is removed. Therefore, you are advised to check the active/standby status of the STG boards before the removal operation. If the STG board to be removed is in active state, switch it to the standby state on the U2000 and then remove it. Usually, it is required to remove an STG board in a switching test scenario. The board removal can be simulated by pulling the ejector lever outward to trigger a micro switch open event. Before performing the simulation, the micro switch function must be enabled again. For details on how to enable the micro switch function, see the Guide to Disable the Micro Switch Function for the OptiX OSN 8800 STG Boards.
Preventive measures:
Solution 1: Upgrade the affected NE to OptiX 8800 V100R007C02SPC300 or a later version. For the method of enabling the micro switch function, see the OptiX OSN 8800 STG Board Upgrade Guide.
Solution 2: Independently upgrade the STG board software and logic to a version matching the OptiX 8800 V100R007C02SPC300 product version. For details on how to perform the upgrade, see the OptiX OSN 8800 STG Board Upgrade Guide. After the upgrade, the micro switch function is disabled by default. If the micro switch function is required, run corresponding commands to enable it. For details, see the OptiX OSN 8800 STG Board Upgrade Guide.
Comments are closed