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The network is unstable and ONTs are flapping

Publication Date:  2018-09-19 Views:  542 Downloads:  2

Issue Description

There are issues in deploying a new GPOL network . The network is unstable and ONTs are flapping. the log of the current issue is presented attached.

This is a completely new infrastructure, one MA5800-x7 is deployed and it is needed to connect some ONT and test them out before starting a massive deployment over the building.

There were no event going on in the network, as it is being built by 0.

Alarm Information

Many LOS/LOF alarms are pesent, as seen from the logs.


! FAULT MAJOR 2018-09-05 15:16:49+02:00 DST
  ALARM NAME :The feeder fiber is broken or OLT can not receive any expected optical signals(LOS)
  PARAMETERS :FrameID: 0, SlotID: 1, PortID: 0,The number of affected ONTs: -, The number of DGi ONTs: -

! RECOVERY CLEARED 2018-09-05 15:17:01+02:00 DST
  ALARM NAME :OLT can receive expected optical signals from ONTs(LOS recovers)
  PARAMETERS :FrameID: 0, SlotID: 1, PortID: 0

! FAULT WARNING 2018-09-05 15:19:49+02:00 DST
  ALARM NAME :The loss of frame of ONTi (LOFi) occurs
  PARAMETERS :FrameID: 0, SlotID: 1, PortID: 0, ONT ID: 0, Equipment ID: EG8040P

Handling Process

Since many LOF/LOS alarms were present, we asked for another detailed log collection that addressed these alarms. The result from the customer is attached "logOLT_debugcmd".



Root Cause

Additional to the LOS/LOF alarms, we found increasing BIP errors, which mean the line quality is not good.



After analyzing the logs, it is suspected the optical line on 0/1/0/0 is abnormal, and advised to measure optical power on the fiber on the ONT. If optical power is normal, try to replace the ONT. If it is abnormal, please replace the fiber connected to the ONT.


After these check-ups, the customer confirmed that the faulty fiber was the reason for the ONT flapping.