Hello,
Today I would like to share with you when rogue ONU causes frequent disconnection of other ONUs.
Symptom
After the flood, all ONUs under a port of a certain site frequently dropped offline.
Warning message
Rogue ONU alarm
Possible Causes
The optical power received by the ONU is greater than the overloaded optical power.
The optical power received by the ONU is less than the sensitivity value.
·Abnormal attenuation on the ODN line.
Steps
1. After communicating with the customer, I learned that the site was hit by floods and some ONUs were flooded.
2. Analysis believes that the flood only flooded part of the ONUs, and should not cause all ONUs on the port to repeatedly disconnect. It is inferred that individual ONUs become rogue ONUs due to abnormal light emission of the optical modules due to flooding.
3. Check one by one at the splitter and found that one ONU emits long light upstream. As shown in Figure 1.
Figure 1 Rogue ONU
4. After the ONU is replaced, system services return to normal.
5. The system runs for a week, and the ONU goes online stably.
Suggestions
Under normal circumstances, the ONU's light-emitting time slot is controlled by the OLT. Rogue ONUs refer to ONUs whose light-emitting time slots are no longer controlled by the OLT and whose optical modules are in a long light-emitting or random light-emitting state. You can check the rogue ONU manually or check the alarm on the OLT. If you find a rogue ONU, please replace the ONU in time
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