Hello everyone!
This time, I will share with you a case about how to handle the BUS_ERR alarm.
Problem Description
At a site of a company, The cross-connect board in slot 73 of the OSN 9800 U32 reports a BUS_ERR alarm.
Handling Process
1. Checked the BUS ERR alarm parameters of the cross-connect board in slot 73 and found that the focus was on the T404 board in slot 29.
2. Perform a cold reset on the cross-connect board. After the cross-connect board starts up, the alarm is reported again.
3. After the cross-connect board is removed, the pins on the backplane are normal. After the board is inserted and powered on, the alarm is reported again.
4. Exchanged the cross-connect board in slot 73 with the cross-connect board in slot 74. The board in slot 73 still reported the BUS_ERR alarm. Therefore, Huawei determined that the cross-connect board in slot 73 was irrelevant to the cross-connect board.
5. Performed a cold reset on the T404 board in slot 29. After the board started up, the BUS_ERR alarm was reported again for the board in slot 73.
6. Removed the board in slot 29 and checked the pins on the backplane. No abnormality was found. After the board was powered on, the alarm was reported again.
7. Exchanged the boards in slots 29 and 27. After the board was powered on, the board in slot 73 reported the BUS ERR alarm. The alarm parameter focused on the board in slot 27. This indicates that the fault is migrated with the original board in slot 29. Therefore, the original board in slot 29 is faulty.
Root Cause
The hardware of the T404 board was damaged. As a result, bit errors occurred in the connection between the board and the cross-connect bus on the backplane, affecting the cross-connection between the board and the board in slot 73. Therefore, the board in slot 73 reported the BUS_ERR alarm.
Solution
Replace the board. The alarm is cleared.
Summary
When the cross-connect board reports a BUS ERR alarm, check the cross-connect board and service board in sequence. If no abnormality is found, the backplane may be faulty.
That's all, welcome everyone to leave a message and exchange in the comment area!
Thank you！
