OLT Fault

Procedure

Check for the possible causes on the OLT and troubleshoot the faults accordingly.

Possible Cause

Judgment Criterion

Troubleshooting Method

The ONU auto discovery function is disabled on the PON port.

Run the display port info command to query the information about the PON port. It is found that Autofind is in the Disable state.

Run the port ont-auto-find command to enable the auto discovery function of the PON port.

NOTE:

By default, the ONU auto discovery function is disabled on a PON port.

The actual distance between the ONU and OLT exceeds the ranging compensation distance configured on the OLT.

Run the display port info command to query the minimum logical reach (Min distance) and maximum logical reach (Max distance) configured for the PON port. It is found that the actual distance between the ONU and OLT exceeds the ranging compensation distance.

For example, the actual length of the optical fiber between the ONU and OLT is about 25 km, which exceeds the ranging compensation distance of 0-20 km.

Run the port range command to adjust the minimum logical reach and maximum logical reach so that the actual distance between the ONU and OLT is within the ranging compensation distance.

NOTE:
  • By default, the ranging compensation distance of a GPON port is from 0 km to 20 km.
  • According to Class B+, the maximum logical reach of a GPON port must not exceed 60 km, and the difference between the minimum logical reach and maximum logical reach must not exceed 20 km.

The laser on the PON port is disabled.

Run the display port info command to query the information about the PON port. It is found that Admin State is in the Off state.

Run the port laser-switch command to enable the laser on the PON port.

NOTE:

By default, the laser on a GPON port is enabled.

The PON port is faulty.
If either of the following two situations occurs, the PON port is faulty.
  • Run the display port state command to query the status of the PON port. It is found that abnormal items exist in the query result. For example, the laser status (Laser state) is abnormal and the transmit optical power (TX power) exceeds the normal range (1.5-5.0 dBm).
  • Migrate the service to another port. It is found that the ONU is auto discovered by the OLT.

Replace the optical module of the PON port or replace the board.

The type of the optical module of the PON port is incorrect.

Run the display port state command to query the port status. xxx NRZ indicates that the optical module is of the GPON type. xxx 10BBB indicates that the optical module is of the EPON type.

Replace the optical module.

The board or the slot is faulty.

Run the display board command to query the status of the board. It is found that the board status is not Normal.

Run the board reset command to reset the board or change the board to another slot. If the fault persist, replace the board.

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