Basic troubleshooting of ONU (optical network unit)

Introduction: ONU (Optical Network Unit) is divided into active optical network unit and passive optical network unit, ONU is the user terminal device in the optical network, placed on the user end, used with OLT to achieve Ethernet Layer 2, Layer 3 functions, to provide users with voice, data and multimedia services.
ONU Panel indicator description:
Power light: Green Off: Power failure; Green On: Power on
PON light: Green on: long on indicates that the board has passed the self-test and the equipment operates normally
LOS Light: Off: Normal
Judge user fault:
Most of the faults are optical fiber line faults and ONU equipment faults. First, check whether the panel indicator is normal. In case of optical fiber line failure, see the status of PON light: if the PON light is green, it indicates that the optical fiber line is normal, and if the PON light is off, it indicates that the optical fiber line is disconnected.
Test the optical fiber line with the optical power meter. The qualified range of optical power is: 1490nm range: – 8dB to – 28dB. If it exceeds the range, it will affect the normal working quality of ONU and the user’s Internet access will be affected. Check the upper level optical fiber line and test the tail fiber of the splitter corresponding to the faulty user’s optical cable at the optical cable box.
The attenuation of the 2-way optical splitter is -3db
The attenuation of the 4-way optical splitter is -6db
The attenuation of the 8-way optical splitter is -9db
The attenuation of the 16-way optical splitter is -12db
The attenuation of the 32-way optical splitter is -15db
The attenuation of the 64-way optical splitter is -18db
1.If the output optical power of the splitter pigtail is qualified, please replace the fiber core between the optical cable transfer box and the building. Generally, we lay at least two fiber cores in the building, and then test at the end after the replacement. If it is the tail from the splitter and its optical power of the fiber is unqualified, please replace the spare pigtail, and use an optical power meter to test a qualified one to connect to the building pigtail.
2.If the optical fiber line is faulty: first unplug the pigtail on the ONU to test the optical power, if there is no light or the power is unqualified, please go to the flange of the optical cable transfer box to find the one of the 1-32 pigtails of the optical splitter corresponding to the ONU If the pigtail is unqualified, you can replace any one of the 1-32 idle pigtails. Remember: the main fiber of the optical splitter cannot be pulled out, which will affect all ONU.

ONU Panel indicator description:
Power light: Green light is always on: Power on; Green light off: Power off
LOS Light: OFF: The received optical power of the PON port is normal; Green light is always on: The device has been discovered and registered; Green light blink: The device has no data; Blink: The PON port has no light or the optical power is lower than the receiving sensitivity.
LAN1, LAN2, LAN3 and LAN4 are all 4RJ45 Port
FXS1 is Voice Port
Troubleshooting: First, check whether the ONU device is running normally (whether the indicator light on the device panel is normal), and then check other reasons after the device is running normally. The procedure is the same as the above.

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