1. On the NMS, check the alarms. Determine the port that reports the alarm according to the alarm parameters. For details, see Viewing the Current Alarms in the Supporting Tasks.

2. Cause 1: The port is enabled, but no signal is accessed from the client side.

   1. If the services on the Ethernet port are deleted but the Ethernet port is still Enabled, the ETH_LOS alarm may be reported. Check whether the port accesses signals from the client side and whether the port is enabled.

   2. If the services at the port are deleted, configure services properly. If the port is no longer required, disable the port. For details on configuring services, see the Configuration Guide (SDH Transport Domain) on the TDM domain and Configuration Guide (Packet Transport Domain) on the packet domain. For details on how to set the attribute of the port for EoS boards, see Configuring the External Port on an Ethernet Board in the Feature Description. For details on how to set the attribute of the port for Ethernet packet boards, see Configuring an Ethernet Port in the Configuration Guide (Packet Transport Domain).

   3. Check whether the alarm is cleared. If the alarm persists, go to 3.

3. Cause 2: The working mode of the local port does not match the working mode of the opposite port.

   1. Query the working modes of the interconnected ports. Determine whether the ports support the auto-negotiation mode, and then select a proper working mode. For details on how to set the working mode of the port for EoS boards, see Configuring the External Port on an Ethernet Board in the Feature Description. For details on how to set the working mode of the port for Ethernet packet boards, see Configuring an Ethernet Port in the Configuration Guide (Packet Transport Domain).

   2. Ensure that the working modes of the interconnected ports are consistent. Then, check whether the alarm is cleared. If the alarm persists, go to 4.

4. Cause 3: The port is enabled, but the network cable or fiber is connected incorrectly or faulty.

• Using the Fiber Cleaner to Clean the Optical Fiber Connector

• Using the Lens Tissue to Clean the Optical Fiber Connector

• Using the Dust-Free Cotton Bar to Clean the Optical Fiber Adapter

1. Check whether the port where the alarm is reported is connected correctly to the network cable or fiber. If the port is connected incorrectly to the network cable or fiber, connect the port to the network cable or fiber correctly according to the requirements of the actual network. Then, check whether the alarm is cleared.

2. Check whether the network cable or fiber jumper at the port is loose. If yes, install the network cable or fiber jumper correctly. Check whether the alarm is cleared.

3. In the case of an optical interface, check whether the fiber connector is dirty. For details, see Checking the Optical Fiber Connector in the Supporting Tasks. If the fiber connector is dirty, clean it immediately. Check whether the alarm is cleared. For details on how to clean the fiber connector, see the Supporting Task.

   
   

   
   

4. If the alarm persists, exchange the cables or fibers to locate the fault. If the cable or fiber is faulty, the Ethernet services may be interrupted. Replace the cable or fiber which may be faulty with a good one. Check whether the alarm is cleared.

5. Check whether the alarm is cleared. If the alarm persists, go to 5.

Cause 4: The opposite board is faulty.

1. In the case of an optical interface board, check whether the transmit optical power of the opposite board is within the normal range on the NMS. For details on the optical power of the board, see in the Hardware Description. For the operations on the NMS, see Querying the Optical Power in the Supporting Tasks.

   
   

   

   You can obtain the manufacturer information about the optical module by referring to Querying the Board Manufacturer Information Report in the Supporting Tasks or Bar Code in the Hardware Description.

   
   

   
   

   If...	Then...
   The transmit optical power on the opposite NE is abnormal	Replace the relevant board. For details, see Replacing an EOS Board in the Parts Replacement. Check whether the alarm is cleared. If the alarm persists, go to 6.
   The transmit optical power on the opposite NE is normal	Go to the next step.

   
   

2. In the case of an electrical interface board, check whether the transmit optical power of the local board is within the normal range on the NMS.

   
   

   If...	Then...
   The transmit optical power on the local NE is abnormal	Go to 6.
   The transmit optical power on the local NE is normal	Go to 5.d.

   
   

3. In the case of an electrical interface board, check whether the board reports the alarms indicating the fault of the board or chip, such as HARD_BAD.

   
   

   If...	Then...
   One of the preceding alarms is reported	Replace the board.
   None of the preceding alarms is reported	Exchange the boards to locate the fault.

   
   

4. If the Ethernet board works with an interface board, replace the interface board first. If the Ethernet board does not work with any interface board, replace the processing board. For details, see Replacing an EOS Board in the Parts Replacement. Check whether the alarm is cleared. If the alarm persists, go to 6.

Cause 5: The local board is faulty.

1. If the Ethernet board works with an interface board, replace the interface board first. If the Ethernet board does not work with an interface board, replace the processing board. For details on how to replace EoS boards, see Replacing an EOS Board in the Parts Replacement. For details on how to replace Ethernet packet boards, see Replacing a Packet Processing Board in the Parts Replacement and Replacing a Packet Interface Board in the Parts Replacement.

2. Check whether the alarm is cleared. If the alarm persists, contact Huawei technical support engineers to handle the alarm.