SmartAX MA5600T/MA5603T Multi-service
Access Module Troubleshooting: ONU Frequently Goes Online and Offline: TC-C6311 An ONT Frequently Goes Online
and Offline Because of Unmatched Optical Fiber Connectors
This topic describes how to troubleshoot the fault when
the deployed ONT frequently goes online and offline because the optical fiber
connectors do not match.
Fault Description
When an ONT is installed in the deployment, the optical path attenuation
is -23 dBm, which is within the normal attenuation range. After the optical
fibers are connected, the LED of the PON port blinks. In addition, the ONT
fails to register with the OLT normally, and the ONT goes online and offline
frequently.
Alarm Information
The up and down alarms about the ONT (OT928) are generated on the OLT.
Cause Analysis
l The
optical path attenuation is very large.
l The
optical fiber connectors are not clean or not connected properly.
Procedure
Step 1 Use an optical power meter to measure the optical path attenuation. It is
found that the optical path attenuation is -23 dBm, which is within the normal
range of the optical path attenuation.
Step 2 It is suspected that the poor quality of optical signals is caused by the
dirty optical fiber connectors of the ONT (OT928). Clean the optical fiber
connectors, and remove and then insert the optical fiber connectors again. The
fault, however, persists.
Step 3 Replace the ONT with another ONT (OT928) to conduct a test. The fault,
however, persists, which indicates that the hardware of the ONT (OT928) is
normal.
Step 4 Check the fiber patch cord of the ONT (OT928). It is found that the
connector of the fiber patch cord does not match the optical fiber connector of
the ONT. Though the connector of the fiber patch cord is square, the color is
different. After verification, the optical fiber connectors used in the ONT
(OT928) are green, square, and SC/APC.
NOTE
The BOM is 14130252, and the
name is Patch Cord, SC/APC-FC/PC, Singlemode-G.652, 3mm, 3m.
Step 5 Replace the fiber patch cord with a correct fiber patch cord
(SC/APC-FC/PC). As a result, the LED of the PON port is stable, and the ONT can
register with the OLT normally.
----End
Suggestion and Conclusion
Currently, the type of the fiber patch cord used in the ONT (OT928) is
seldom used in China, but is mostly used abroad. Therefore, note that you
should use the correct fiber patch cord.
The greatest difference between green and blue fiber patch cords is as
follows: The
interconnection section between the fiber patch cord with green connectors
and the OT928 is oblique. The interconnection section between the fiber patch
cord with blue connectors and the ONT is plane, which can result in 3-6 dBm
optical attenuation.
