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how can i deal with OA LOW GAIN ALARM (RAU201)

Created: Mar 13, 2020 19:19:42Latest reply: Mar 19, 2020 12:36:48 932 4 0 0 0
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I have OA LOW GAIN ALARM (RAU201) on my network. what is the  steps to solve the alam

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liqiang185
Admin Created Mar 14, 2020 03:10:28

Dear ZXcvbn!
The RAU201 board is a Raman amplifier board.
If the OA_LOW_GAIN alarm is generated on the RAU201 board, handle the alarm as follows:
Cause 1: The quality of the fiber 30 km near the board deteriorates or the end face of the fiber is burnt.
Check the end face of the fiber using a fiberscope and check the fiber quality using an OTDR. When checking the fiber quality using an OTDR, you are advised to connect a temporary fiber longer than 5000 m between the ODF and the OTDR.If the end face of the fiber is burnt, replace or re-splice the fiber. If the fiber quality deteriorates, contact Huawei to rectify the fiber link or decrease the gain of the Raman optical module.
Cause 2: The insertion loss of the near-end fiber connector is too large.
Check the fiber connection using an appropriate meter.
Cause 3: The span is too short.
Check whether the span is greater than 70 km.
Cause 4: The configured fiber type is inconsistent with the actual fiber type.
Check whether the specified fiber type matches the fiber in use. If they mismatch, set the fiber type again so that they match each other.
Cause 5: The currently configured gain is out of the gain range of the new fibers after the fiber type is changed.
Check whether the current nominal gain is higher than the maximum nominal gain of the new fiber. If it is, reset the nominal gain to ensure that it is within the permitted range.
Cause 6: A fault occurs on the board. For example, the pump laser is aging or faulty, or the gain locking unit is faulty.
Replace the board.

Generally, there are the preceding six cases. The line attenuation is excessively large and the board hardware is faulty. You are advised to focus on the two cases.

Thank you!
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wissal
MVE Created Mar 13, 2020 19:49:41

Hello,

Please find the answer for your issue.

OA_LOW_GAIN

Description

Gain of an optical amplifier (OA) board being low. This alarm is generated when the actual gain of an OA board (except the Raman optical module of the RAU board) is 3 dB lower than the nominal gain. For the Raman optical module of the RAU board, the alarm is generated when the actual gain is 2 dB lower than the nominal gain.

Attribute

Alarm Severity

Alarm Type

Critical

Service alarm

Parameters

None

Impact on the System

The impacts of this alarm vary according to the alarm causes:

  • If the alarm is generated because the input optical power is excessively high, the redundancy of the system decreases, which affects the subsequent capacity expansion.

  • If the alarm is caused by other factors (for example, excessive insertion loss between the TDC and RDC optical ports on an OAU board), the input optical power of the downstream signals and the redundancy of the system decrease. The services may have bit errors or even be interrupted.

Fault Symptom

Table 1 lists the fault symptom for the OA_LOW_GAIN alarm.
Table 1 Fault symptom for the OA_LOW_GAIN alarm

Fault Symptom

Cause

The OAU board that reports this alarm also reports a power high alarm, such as SUM_INPWR_HI.

Cause 1: The input optical power of the OAU board is excessively high.

note_3.0-en-us.png

If the fault has no symptom, or if the fault symptom is different from the one described in this topic, handle the fault according to "Handling Procedure" provided in this topic.

Possible Causes

For optical amplifier boards and the EDFA optical module of the RAU board and SRAU board, the alarm caused by different factors has different impacts on the system:

  • Cause 1: The input optical power of the board is excessively high.

  • Cause 2: This alarm may be generated because the insertion loss between the TDC and RDC optical ports is excessively high. (This cause is applicable only to the OAU board.)

  • Cause 3: The board that reports the alarm is faulty.

For the Raman optical module of the RAU board and SRAU board, the alarm caused by different factors has different impacts on the system:

  • Cause 1: The quality of the fiber 30 km near the board deteriorates or the end face of the fiber is burnt.

  • Cause 2: The insertion loss of the near-end fiber connector is too large.

  • Cause 3: The span is too short.

  • Cause 4: The configured fiber type is inconsistent with the actual fiber type.

  • Cause 5: The current configured gain is out of the gain range of the new fibers after the fiber type is changed.

  • Cause 6: A fault occurs on the board. For example, the pump laser is aging or faulty, or the gain locking unit is faulty.

Procedure

  • For optical amplifier boards and the EDFA optical module of the RAU board and SRAU board:


  1. Replace the faulty board. If this board supports pluggable optical modules, replace the pluggable optical modules. If this board does not support pluggable optical modules, replace the faulty board.

  2. Check whether the alarm is cleared. If the alarm persists, contact Huawei engineers for help.

  1. On the NMS, check the optical power at the TDC and RDC optical ports on the OAU, and then calculate the insertion loss between the TDC and RDC optical ports. For details, refer to "Querying the Insertion Loss Between the TDC and RDC optical ports on the OAU board".

    note_3.0-en-us.png

    Insertion loss = Optical power at the TDC optical port - Optical power at the RDC optical port. On the NMS, the difference between the optical power at optical port 3 and the optical power at optical port 5 represents the insertion loss.

  2. If the insertion loss is excessive, clean the fiber jumper and fiber connector between the TDC and RDC optical ports. For details, refer to "Inspecting and Cleaning the Fiber-Optic Connectors". For the insertion loss specification, see the Product Description.

  3. Check whether the alarm is cleared. If the alarm persists, replace the DCM module between the TDC and RDC optical ports.

  4. Check whether the alarm is cleared. If the alarm persists, see the alarm handling procedure for cause 3.

  1. On the NMS, check whether the receive optical power of the board is within the permitted range.

  2. If the input optical power is not within the permitted range, adjust the optical attenuator attached to the input optical port so that the input optical power meets the specification requirement. For details, see "Adjusting, Replacing, Adding and Removing Attenuator" in the Supporting Tasks.

  3. If no optical attenuator is attached to the input optical port, add an optical attenuator to ensure that the input optical power meets the specification requirement. For details, see "Adjusting, Replacing, Adding and Removing Attenuator" in the Supporting Tasks.

  4. Check whether the alarm is cleared. If the alarm persists, see the alarm handling procedure for cause 2.

  1. Cause 1: The input optical power of the board is excessively high.

  2. Cause 2: The insertion loss between the TDC and RDC optical ports is excessively high. (This cause is applicable only to the OAU board.)

  3. Cause 3: The board that reports the alarm is faulty.

For the Raman optical module of the RAU board and SRAU board:


  1. Cause 1: The quality of the fiber 30 km near the board deteriorates or the end face of the fiber is burnt.

    1. Check the end face of the fiber using a fiberscope and check the fiber quality using an OTDR. When checking the fiber quality using an OTDR, you are advised to connect a temporary fiber longer than 5000 m between the ODF and the OTDR.If the end face of the fiber is burnt, replace or re-splice the fiber. If the fiber quality deteriorates, contact Huawei to rectify the fiber link or decrease the gain of the Raman optical module.

  2. Cause 2: The insertion loss of the near-end fiber connector is too large.

    1. Check the fiber connection using an appropriate meter.

  3. Cause 3: The span is too short.

    1. Check whether the span is greater than 70 km.

  4. Cause 4: The configured fiber type is inconsistent with the actual fiber type.

    1. Check whether the specified fiber type matches the fiber in use. If they mismatch, set the fiber type again so that they match each other.

  5. Cause 5: The current configured gain is out of the gain range of the new fibers after the fiber type is changed.

    1. Check whether the current nominal gain is higher than the maximum nominal gain of the new fiber. If it is, reset the nominal gain to ensure that it is within the permitted range.

  6. Cause 6: A fault occurs on the board. For example, the pump laser is aging or faulty, or the gain locking unit is faulty.

    1. Replace the board.


Reference : https://support.huawei.com/hedex/hdx.do?lib=EDOC110007394831180AGN&docid=EDOC1100073948&lang=en&v=03&tocLib=EDOC110007394831180AGN&tocV=03&id=EN-US_ALARMREF_0157957481&tocURL=resources%2fhelp%2fwdm%2fcom%2fap%2falm%5fproc%5flong%2foa%5flow%5fgain%2ehtml&p=t&fe=1&ui=3&keyword=OA%252BLOW%252BGAIN%252BALARM

Thanks

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All Answers
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2#
wissal
wissal MVE Created Mar 13, 2020 19:49:41

Hello,

Please find the answer for your issue.

OA_LOW_GAIN

Description

Gain of an optical amplifier (OA) board being low. This alarm is generated when the actual gain of an OA board (except the Raman optical module of the RAU board) is 3 dB lower than the nominal gain. For the Raman optical module of the RAU board, the alarm is generated when the actual gain is 2 dB lower than the nominal gain.

Attribute

Alarm Severity

Alarm Type

Critical

Service alarm

Parameters

None

Impact on the System

The impacts of this alarm vary according to the alarm causes:

  • If the alarm is generated because the input optical power is excessively high, the redundancy of the system decreases, which affects the subsequent capacity expansion.

  • If the alarm is caused by other factors (for example, excessive insertion loss between the TDC and RDC optical ports on an OAU board), the input optical power of the downstream signals and the redundancy of the system decrease. The services may have bit errors or even be interrupted.

Fault Symptom

Table 1 lists the fault symptom for the OA_LOW_GAIN alarm.
Table 1 Fault symptom for the OA_LOW_GAIN alarm

Fault Symptom

Cause

The OAU board that reports this alarm also reports a power high alarm, such as SUM_INPWR_HI.

Cause 1: The input optical power of the OAU board is excessively high.

note_3.0-en-us.png

If the fault has no symptom, or if the fault symptom is different from the one described in this topic, handle the fault according to "Handling Procedure" provided in this topic.

Possible Causes

For optical amplifier boards and the EDFA optical module of the RAU board and SRAU board, the alarm caused by different factors has different impacts on the system:

  • Cause 1: The input optical power of the board is excessively high.

  • Cause 2: This alarm may be generated because the insertion loss between the TDC and RDC optical ports is excessively high. (This cause is applicable only to the OAU board.)

  • Cause 3: The board that reports the alarm is faulty.

For the Raman optical module of the RAU board and SRAU board, the alarm caused by different factors has different impacts on the system:

  • Cause 1: The quality of the fiber 30 km near the board deteriorates or the end face of the fiber is burnt.

  • Cause 2: The insertion loss of the near-end fiber connector is too large.

  • Cause 3: The span is too short.

  • Cause 4: The configured fiber type is inconsistent with the actual fiber type.

  • Cause 5: The current configured gain is out of the gain range of the new fibers after the fiber type is changed.

  • Cause 6: A fault occurs on the board. For example, the pump laser is aging or faulty, or the gain locking unit is faulty.

Procedure

  • For optical amplifier boards and the EDFA optical module of the RAU board and SRAU board:


  1. Replace the faulty board. If this board supports pluggable optical modules, replace the pluggable optical modules. If this board does not support pluggable optical modules, replace the faulty board.

  2. Check whether the alarm is cleared. If the alarm persists, contact Huawei engineers for help.

  1. On the NMS, check the optical power at the TDC and RDC optical ports on the OAU, and then calculate the insertion loss between the TDC and RDC optical ports. For details, refer to "Querying the Insertion Loss Between the TDC and RDC optical ports on the OAU board".

    note_3.0-en-us.png

    Insertion loss = Optical power at the TDC optical port - Optical power at the RDC optical port. On the NMS, the difference between the optical power at optical port 3 and the optical power at optical port 5 represents the insertion loss.

  2. If the insertion loss is excessive, clean the fiber jumper and fiber connector between the TDC and RDC optical ports. For details, refer to "Inspecting and Cleaning the Fiber-Optic Connectors". For the insertion loss specification, see the Product Description.

  3. Check whether the alarm is cleared. If the alarm persists, replace the DCM module between the TDC and RDC optical ports.

  4. Check whether the alarm is cleared. If the alarm persists, see the alarm handling procedure for cause 3.

  1. On the NMS, check whether the receive optical power of the board is within the permitted range.

  2. If the input optical power is not within the permitted range, adjust the optical attenuator attached to the input optical port so that the input optical power meets the specification requirement. For details, see "Adjusting, Replacing, Adding and Removing Attenuator" in the Supporting Tasks.

  3. If no optical attenuator is attached to the input optical port, add an optical attenuator to ensure that the input optical power meets the specification requirement. For details, see "Adjusting, Replacing, Adding and Removing Attenuator" in the Supporting Tasks.

  4. Check whether the alarm is cleared. If the alarm persists, see the alarm handling procedure for cause 2.

  1. Cause 1: The input optical power of the board is excessively high.

  2. Cause 2: The insertion loss between the TDC and RDC optical ports is excessively high. (This cause is applicable only to the OAU board.)

  3. Cause 3: The board that reports the alarm is faulty.

For the Raman optical module of the RAU board and SRAU board:


  1. Cause 1: The quality of the fiber 30 km near the board deteriorates or the end face of the fiber is burnt.

    1. Check the end face of the fiber using a fiberscope and check the fiber quality using an OTDR. When checking the fiber quality using an OTDR, you are advised to connect a temporary fiber longer than 5000 m between the ODF and the OTDR.If the end face of the fiber is burnt, replace or re-splice the fiber. If the fiber quality deteriorates, contact Huawei to rectify the fiber link or decrease the gain of the Raman optical module.

  2. Cause 2: The insertion loss of the near-end fiber connector is too large.

    1. Check the fiber connection using an appropriate meter.

  3. Cause 3: The span is too short.

    1. Check whether the span is greater than 70 km.

  4. Cause 4: The configured fiber type is inconsistent with the actual fiber type.

    1. Check whether the specified fiber type matches the fiber in use. If they mismatch, set the fiber type again so that they match each other.

  5. Cause 5: The current configured gain is out of the gain range of the new fibers after the fiber type is changed.

    1. Check whether the current nominal gain is higher than the maximum nominal gain of the new fiber. If it is, reset the nominal gain to ensure that it is within the permitted range.

  6. Cause 6: A fault occurs on the board. For example, the pump laser is aging or faulty, or the gain locking unit is faulty.

    1. Replace the board.


Reference : https://support.huawei.com/hedex/hdx.do?lib=EDOC110007394831180AGN&docid=EDOC1100073948&lang=en&v=03&tocLib=EDOC110007394831180AGN&tocV=03&id=EN-US_ALARMREF_0157957481&tocURL=resources%2fhelp%2fwdm%2fcom%2fap%2falm%5fproc%5flong%2foa%5flow%5fgain%2ehtml&p=t&fe=1&ui=3&keyword=OA%252BLOW%252BGAIN%252BALARM

Thanks

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  • convention：
(1) (0)
3#
liqiang185
liqiang185 Admin Created Mar 14, 2020 03:10:28

Dear ZXcvbn!
The RAU201 board is a Raman amplifier board.
If the OA_LOW_GAIN alarm is generated on the RAU201 board, handle the alarm as follows:
Cause 1: The quality of the fiber 30 km near the board deteriorates or the end face of the fiber is burnt.
Check the end face of the fiber using a fiberscope and check the fiber quality using an OTDR. When checking the fiber quality using an OTDR, you are advised to connect a temporary fiber longer than 5000 m between the ODF and the OTDR.If the end face of the fiber is burnt, replace or re-splice the fiber. If the fiber quality deteriorates, contact Huawei to rectify the fiber link or decrease the gain of the Raman optical module.
Cause 2: The insertion loss of the near-end fiber connector is too large.
Check the fiber connection using an appropriate meter.
Cause 3: The span is too short.
Check whether the span is greater than 70 km.
Cause 4: The configured fiber type is inconsistent with the actual fiber type.
Check whether the specified fiber type matches the fiber in use. If they mismatch, set the fiber type again so that they match each other.
Cause 5: The currently configured gain is out of the gain range of the new fibers after the fiber type is changed.
Check whether the current nominal gain is higher than the maximum nominal gain of the new fiber. If it is, reset the nominal gain to ensure that it is within the permitted range.
Cause 6: A fault occurs on the board. For example, the pump laser is aging or faulty, or the gain locking unit is faulty.
Replace the board.

Generally, there are the preceding six cases. The line attenuation is excessively large and the board hardware is faulty. You are advised to focus on the two cases.

Thank you!
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  • convention：
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4#
ZXcvbn
ZXcvbn Created Mar 19, 2020 12:36:48

many thanks
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liqiang185
liqiang185 Created Mar 20, 2020 00:33:35 (0) (0)
You are welcome. If you have any other questions, please continue to post in our forum. At the same time, you can also share your knowledge and experience, and let us be technical masters together  
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