2014年2月10日星期一

MA5603T: Failure to Go Online of an ONU

MA5603T: Failure to Go Online of an ONU, below is the reason analysis and solution. 
The ONU going online failure is a fault in which an ONU fails to go online normally, and the queried Run state of the ONU is displayed as offline by running the display ont info command on the OLT.
Fault Description
Network topology: Optical split level: two levels; level-one split ratio: 1:2; level-two split ratio: 1:16; backbone fiber: 2.2 km long; branch fibers: 500 m to 24 km long
During deployment in an office, the receive optical power of all ONUs under two-level optical splitters is normal but the ONUs fail to go online.

Alarm Information
None

Possible Cause
l The ONU receive optical power is larger than the overload optical power.
l The ONU receive optical power is smaller than the sensitivity.
l There is abnormal attenuation on ODN lines.
l The distance between the ODN Max. receive optical power and Min. optical power exceeds the threshold.

Procedure
Step 1 Analyze the network. It is found that the distance between the farthest ONU and the OLT is over 20 km and the distance between the farthest and nearest ONUs is also over 20 km, as shown in Figure 1.

Step 2 Plan the ODN again and connect the ONUs whose fibers are longer than 20 km to another PON port. Then, ONUs normally go online.
Step 3 Such a fault does not recur in the next week.
----End

Suggestion and Conclusion
Make sure that the distance between the farthest ONU and the nearest ONU under a PON port is smaller than 20 km.
The similar products MA5683T also works for this solution.


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