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The Signal Interference of a Repeater in a Base Station Causes that the OptiX Metro 1000 Transiently Reports the ROOF Alarm

Publication Date:  2012-07-25 Views:  51 Downloads:  0
Issue Description
In an office, the networking is as follows:
Optical interface 1 on the SQ1 board in slot 4 of the OptiX 2500+ at station A is connected to optical interface 1 on the OI2D board in slot 1 of the OptiX Metro 1000 V300 at station B, and optical interface 2 on the OI2D board in slot 1 of the OptiX Metro 1000 V300 at station B is connected to optical interface 1 on the OI2D board in slot 1 of the OptiX Metro 1000 V300 at station C to form a non-protection chain. One day, the NEs at both ends of the OptiX Metro 1000 V300 at station B receive the ROOF alarm that is transiently reported by an optical board. 
 
Alarm Information
ROOF 
Handling Process
1. Query alarm information. The query result shows that NE B does not report any alarm. The optical board that is interconnected with NE A and NE C transiently reports the ROOF alarm.
2. Query the performance events of NEs A, B, and C. The OI2D optical board of NE B has multiplex section (MS) bit errors and remote background block errors (BBEs) of the higher order path. The optical boards on NE A and NE C that are interconnected with NE B have regenerator section (RS) bit errors, MS bit errors, and higher order path errors. The reporting time of these performance events agrees with the reporting time of the ROOF alarm.
3. Query the receive optical power and the transmit optical power of the OI2D optical board of NE B and the receive optical power and the transmit optical power of the corresponding optical board at the opposite end. They are all normal.
4. Replace the OI2D board and the SCB of NE in turn. The problem persists.
5. It is suspected that the problem is caused by an external condition. Check the grounding condition, and the check result shows that the grounding condition is well. Check whether an interference source exists in the base station. The check result shows that one repeater is available in the base station. Turn off the repeater. Then, the OptiX Metro1000 V300 at station B does not report the ROOF alarm. Query the performance events of each station, bit errors do not exist. Therefore, the problem is solved. 
 
Root Cause
1. The clock board failure of NE B causes that the adjacent NEs at both ends receive the ROOF alarm that is transiently reported by an optical board.
2. The OI2D optical board failure of NE B causes that the adjacent NEs at both ends receive the ROOF alarm that is transiently reported by an optical board.
3. The signal interference of NE B causes that the adjacent opposite NEs receive the ROOF alarm that is transiently reported by an optical board. 
 
Suggestions
The anti-interference capability of the OptiX Metro 1000 is poor (and therefore an EMC tray assembly is provided for the OptiX Metro 1000). It is recommended that you install the antenna of a repeater in a wireless based station outside the equipment room or a place that is far away from the transmission equipment to prevent an interference upon optical signals. 

END