March 31, 2015

Be aware of SSN3PSXCSA replace Cross-connect Board on OptiX OSN 3500

Summary:

When an SSN3PSXCSA (Ver.B) board is used to replace another cross-connect board, after theSSN3PSXCSA (Ver.B) board is inserted into the subrack, the state of the original active cross-connect board is abnormal and NE services are interrupted. After about 40s, the state of the original active board is back to normal and services recover.

[Problem Description]Fault symptoms:

When an SSN3PSXCSA (Ver.B) board is inserted into the slot of the standby cross-connect board, the ACT indicator of the active cross-connect board turns from steady green to off and services are interrupted. The NE may report the PLL_FAIL alarm of service boards.
Trigger conditions:
Use an SSN3PSXCSA (Ver.B) board to replace another kind of cross-connect board. This problem does not occur if the original active cross-connect board is an SSN3PSXCSA board.
Identification method:
This problem can be identified if the following conditions are met.

  • Services are interrupted for about 40s when you use an Huawei OptiX OSN 3500 SSN3PSXCSA (Ver.B) board to replace a non-SSN3PSXCSA cross-connect board.
  • The new board must be an SSN3PSXCSA board in Ver.B, which can be verified by checking the silkscreen on the board, as is shown in the following figure:

After the board starts, you can also obtain the board version using the NMS.

[Root Cause]
When the SSN3PSXCSA (Ver.B) board is powered on as a standby cross-connect board, before the logic is loaded, the status bus sent to the active cross-connect board is incorrect. As a result, the active cross-connect board is switched to be a standby board and services are interrupted. After the logic of the board is loaded, the status bus sent to the original active board, the status of the original active board and NE services are all back to normal. The service interruption lasts for about 40s.

[Impact and Risks]
When the SSN3PSXCSA (Ver.B) board is inserted into the slot of standby cross-connect board and the active cross-connect board is not an SSN3PSXCSA (Ver.B) board, services are interrupted for about 40s.

[Measures and Solutions]
Recovery measures:
Remove the SSN3PSXCSA (Ver.B) board from the slot of standby cross-connect board.
Workaround:
For different board versions, when a board is used to replace a different board, different commands are required to forcibly stop the active/standby switching. For a specific scenario, contact GTAC to obtain the corresponding command.
Solution:
Use an SSN3PSXCSA in Ver.C to perform the board replacement.
Material handling after replacement:
Use SSN3PSXCSA (Ver.B) boards as good boards to replace other SSN3PSXCSA boards on huawei transmission equipment.

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