An ONU connected to a
GPON port of an OLT fails to go online normally, but the queried Run state of the ONU is displayed as offline by running the display ont info command on the
OLT.
Location Method
NOTE:
Going online refers to a process that after being powered on, an ONU registers with an OLT and sets up a management channel with the OLT. An ONU can be managed by the OLT and be configured with services only after going online.
When an ONU fails to go online, locate the fault based on the following fault symptoms and possible causes.
Possible Cause
Judgment Criterion
Troubleshooting Method
The SN configured on the OLT is different from the actual SN of the ONU; hence, the ONU fails to pass authentication and to go online.
Run the display ont info command to query the ONU information. It is found that the SN in the result is different from the actual ONU SN.
Run the ont add command to re-add an ONU and specify the correct ONU SN and password.
NOTE:
The ONU with a different SN is regarded as a new one and is founded by the OLT.
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 GPON 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 OLT deactivates the ONU.
Run the display ont info command to query the ONU information. It is found that Control flag is displayed as deactive.
Run the ont activate command to activate an ONU.
NOTE:
When an ONU is activated, its optical module only receives optical signals but does not transmit optical signals.
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 Laser switch 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 pot 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 goes online normally.
Replace the optical module of the PON port or replace the board.
The board or the slot is faulty.
All the ONUs connected to the board fail to go online.
Change the board to another slot. If the fault persist, replace the board.
CAUTION:
To facilitate fault report, save the results of the following steps.
The parameters of the optical module in this topic comply with Class B+. Note that such parameters are slightly different from the parameters in Class C.
Procedure
1.When the queried Run state of the ONU is displayed as offline, check whether the OLT generates the following alarms. If such alarms are generated, clear them and check whether the fault is rectified. If the fault persists, proceed to 2.
The following alarms may be generated:
2.Check for the possible causes on the OLT and troubleshoot the faults accordingly. If the ONU still fails to go online after that, proceed to 3.
Possible Cause
Judgment Criterion
Troubleshooting Method
The SN configured on the OLT is different from the actual SN of the ONU; hence, the ONU fails to pass authentication and to go online.
Run the display ont info command to query the ONU information. It is found that the SN in the result is different from the actual ONU SN.
Run the ont add command to re-add an ONU and specify the correct ONU SN and password.
NOTE:
The ONU with a different SN is regarded as a new one and is founded by the OLT.
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 GPON 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 OLT deactivates the ONU.
Run the display ont info command to query the ONU information. It is found that Control flag is displayed as deactive.
Run the ont activate command to activate an ONU.
NOTE:
When an ONU is activated, its optical module only receives optical signals but does not transmit optical signals.
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 Laser switch 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 pot 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.
Replace the optical module of the PON port or replace the board.
The board or the slot is faulty.
All the ONUs connected to the board fail to go online.
Change the board to another slot. If the fault persist, replace the board.
3.Check for the possible causes on the ODN and troubleshoot the faults accordingly. If the ONU still fails to go online after that, proceed to 4.
4.Check for the possible causes on the ONU and troubleshoot the faults accordingly. If the ONU still fails to go online after that, proceed to 5.
5.Record the results of the preceding steps in the form for reporting a fault, fill in the form completely, and then submit the form to
Huawei for technical support.
6.The fault is rectified.
Telephone: 852-30623083
