Huawei HG8245T Router Manual PDF (Setup & Configuration Guide)

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Fault Type

Abnormal ONU connection

Keyword

Too long fiber

Failure to report the SN

Failure to discover the ONU

Fault Description

Network topology: Optical split level: two levels; level-one split ratio: 1:2; level-two split ratio:

1:16; backbone fiber: 1 km long; branch fibers: 15 km to 24 km long

During deployment in an office, the receive optical power of some ONUs is normal but the

ONUs fail to report their SNs or go online. Remove the ONUs and install them in the

telecommunications room. It is found that they work normally.

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

ODN lines are too long and exceed the online distance preset in the system.

Procedure

Step 1

Analyze the network conditions. It is found that the distance of the nearest ONU is longer than

10 km and the distance of the farthest ONU is shorter than 30 km but longer than 20 km, which

is the Max. online distance (20 km) preset in the system. The network diagram is shown in

Figure 5-20

.

Figure 5-20

Network Diagram

EchoLife HG8010/HG8240B/HG8245T/HG8247T GPON

Terminal

Service Manual

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Step 2

The ONU goes online after the ONU Max. online distance and Min. online distance are changed

to 30 km and 10 km respectively by running the

port range

command on the OLT.

Step 3

Such a fault does not recur in the next week.

----End

Suggestion and Conclusion

The default ONU Max. online distance is 20 km. If the distance between the ONU and the OLT

exceeds 20 km, change the ONU Max. online distance.

5.8.4 ONU Frequently Goes Online and Offline

The ONU frequently going online and offline failure is a fault in which an ONU connected to a

PON port of an OLT frequently goes online and offline and therefore the OLT reports a large

number of ONU LOS and ONU signal recovery alarms.

TC-C6007 An ONU Goes Online and Offline Repeatedly Because of Unstable

Voltage

This topic describes how to troubleshoot the fault when an ONU goes online and offline

repeatedly and alarms that the ONU goes online and offline repeatedly are generated on the OLT

because of unstable voltage.

Fault Type

Service failure

Keyword

Going online and offline repeatedly

Repeated reset

Fault Description

An ONU connected to an OLT in an office goes online and offline repeatedly and irregularly.

Alarm Information

Alarms that the ONU goes online and offline repeatedly are generated on the OLT.

Cause Analysis

l

The optical fiber attenuation is very large.

l

The hardware of the ONU is faulty.

l

The boards on the OLT are faulty.

EchoLife HG8010/HG8240B/HG8245T/HG8247T GPON

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Procedure

Step 1

Other ONUs connected to the PON port are normal, which indicates that the PON board of the

OLT is normal.

Step 2

Use an optical power meter to test the optical fiber attenuation on the ONU side. It is found that

the optical fiber attenuation is -20 dB, which is normal. This indicates that the line is normal.

Step 3

Replace the ONU with another ONU. The fault, however, persists, which indicates that the

hardware of the ONU is normal.

Step 4

The ONU on which the fault occurs is located in a remote mountain area. Therefore, it is

suspected that the fault is caused by the surroundings. Log in to the ONU in the telnet mode,

and then run the

display alarm list all

command to carefully view the alarms. It is found that

the ONU resets in peak hours from 7:00 a.m. to 8:00 p.m. in four consecutive days. Therefore,

it can be preliminarily determined that the fault is caused by the voltage.

Step 5

Use a multimeter to test the voltage on site. It is found that the ONU resets repeatedly due to

unstable voltage. Replace the ONU with another ONU with the DC module. As a result, the fault

is rectified.

----End

Suggestion and Conclusion

The ONUs of Huawei support AC power supply and DC power supply. If an ONU uses the AC

power supply, the ONU resets repeatedly when the voltage is unstable. If the voltage is abnormal

and the normal voltage cannot be guaranteed, it is recommended that you use an ONU with the

DC module.

TC-C6311 An ONT Frequently Goes Online and Offline Because of Unmatched

Optical Fiber Connectors

This topic describes how to troubleshoot the fault when the deployed ONT frequently goes online

and offline because the optical fiber connectors do not match.

Fault Type

GPON service

Keyword

Fiber patch cord

Optical fiber connector

Fault Description

When an ONT is installed in the deployment, the optical path attenuation is -23 dBm, which is

within the normal attenuation range. After the optical fibers are connected, the LED of the PON

port blinks. In addition, the ONT fails to register with the OLT normally, and the ONT goes

online and offline frequently.

EchoLife HG8010/HG8240B/HG8245T/HG8247T GPON

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Alarm Information

The up and down alarms about the ONT (OT928) are generated on the OLT.

Cause Analysis

l

The optical path attenuation is very large.

l

The optical fiber connectors are not clean or not connected properly.

Procedure

Step 1

Use an optical power meter to measure the optical path attenuation. It is found that the optical

path attenuation is -23 dBm, which is within the normal range of the optical path attenuation.

Step 2

It is suspected that the poor quality of optical signals is caused by the dirty optical fiber

connectors of the ONT (OT928). Clean the optical fiber connectors, and remove and then insert

the optical fiber connectors again. The fault, however, persists.

Step 3

Replace the ONT with another ONT (OT928) to conduct a test. The fault, however, persists,

which indicates that the hardware of the ONT (OT928) is normal.

Step 4

Check the fiber patch cord of the ONT (OT928). It is found that the connector of the fiber patch

cord does not match the optical fiber connector of the ONT. Though the connector of the fiber

patch cord is square, the color is different. After verification, the optical fiber connectors used

in the ONT (OT928) are green, square, and SC/APC.

NOTE

The BOM is 14130252, and the name is Patch Cord, SC/APC-FC/PC, Singlemode-G.652, 3mm, 3m.

Step 5

Replace the fiber patch cord with a correct fiber patch cord (SC/APC-FC/PC). As a result, the

LED of the PON port is stable, and the ONT can register with the OLT normally.

----End

Suggestion and Conclusion

Currently, the type of the fiber patch cord used in the ONT (OT928) is seldom used in China,

but is mostly used abroad. Therefore, note that you should use the correct fiber patch cord.

The greatest difference between green and blue fiber patch cords is as follows: The

interconnection section between the fiber patch cord with green connectors and the OT928 is

oblique. The interconnection section between the fiber patch cord with blue connectors and the

ONT is plane, which can result in 3-6 dBm optical attenuation.

TC-C6207 ONU Frequent Going Online and Offline Because of Mismatching Fiber

Connector

This topic describes how to troubleshoot the fault of ONU frequent going online and offline.

Fault Type

Abnormal ONU connection

Keyword

Fiber connector

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Terminal

Service Manual

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ONU frequent going offline

ONU frequent going online and offline

Fault Description

Network topology: Optical split level: one level; split ratio: 1:32; connector: SC/APC connector

In an office, an ONU frequently goes online and offline.

Alarm Information

LOSi alarm and LOFi alarm

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.

Procedure

Step 1

Test the receive optical power on ONU optical ports. It is found that the receive optical power

is -27 dBm. This indicates that there is abnormal attenuation on ODN lines.

Step 2

Perform a test on the optical splitter. It is found that the connector of the optical splitter is an

SC/APC connector but that of the ONU fiber is an SC/PC connector. When an APC-endface

fiber is connected to a PC-endface fiber, at least 3 dB attenuation will be generated, as shown

in

Figure 5-21

.

Figure 5-21

Interconnection of PC and APC connectors

Step 3

Remove the SC/PC fiber (blue) and splice it to an SC/APC fiber (green). Test the ONU receive

optical power again. It is found that the receive optical power becomes -23.5 dBm, which is

within the normal range. This indicates that the mismatching fiber connector causes abnormal

attenuation on ODN lines and consequently causes the ONU to go online and offline frequently.

EchoLife HG8010/HG8240B/HG8245T/HG8247T GPON

Terminal

Service Manual

5 Maintenance and Troubleshooting

Issue 01 (2011-10-18)

Huawei Proprietary and Confidential

402

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