An Optical Interface Cannot Turn Up

Fault Description

After an optical interface is connected to a remote device through an optical fiber, its LINK indicator is off.

Possible Causes

• The optical fiber is faulty.
• The optical module on the optical interface cannot meet the requirements.
• The optical attenuator used cannot meet the requirements.
• A combo interface is used but the interface type is not set to optical interface.

• There are four combo interfaces GE0/0/21, GE0/0/22, GE0/0/23 and GE0/0/24 on the main control board of the AC6605, and the four interfaces function independently.
• There are two combo interfaces GE0/0/7 and GE0/0/8 on the main control board of the AC6005, and the two interfaces function independently.
• There are four combo interfaces XGE0/0/1, XGE0/0/2, XGE0/0/3, and XGE0/0/4 on the main control board of the AC6805, and the four interfaces function independently.
• There are four combo interfaces XGE0/0/1, XGE0/0/2, XGE0/0/3, and XGE0/0/4 on the main control board of the AirEngine 9700-M, and the four interfaces function independently.

Troubleshooting Procedure

1. Replace the optical fiber and optical module and check whether the optical interface can turn Up. Ensure that the optical module meets the following requirements.
2. Determine optical module attributes.
   • The optical module has passed Huawei certification.
   • The transmission speed of the optical module is the same as the interface speed.
   • Check whether the wavelength of the optical module is the same as that of the remote optical module.
   • The transmission distance of the optical module is suitable for the actual distance between the two devices.
   • The transmission distance of an optical module is 10 km, 15 km, 20 km, 40 km, or 80 km. The optical modules with a longer transmission distance have a higher transmit power. If an optical module with a long transmission distance is used for short-distance transmission, the optical interface cannot turn Up because the transmit power is too high. The high transmit power may even burn the receiver of the remote optical module. To reduce the transmit power in this situation, use an optical attenuator between the optical module and optical fiber.
   • Optical modules with different speeds are available, for example, 155 Mbit/s, 622 Mbit/s, and 1.25 Gbit/s. You must use an optical module with the same speed as the optical interface to ensure efficient optical transmission.

3. If the interface is a combo interface, run the display this command in the interface view to check whether the interface type has been set to auto or optical interface.

   <AC6605> system-view 
   Enter system view, return user view with Ctrl+Z 
   [AC6605] interface GigabitEthernet 0/0/24 
   [AC6605-GigabitEthernet0/0/24] display this 
   # 
   interface GigabitEthernet0/0/24 
   combo-port copper 
   # 
   Return

   If the combo interface type is electrical interface, run the combo-port auto or combo-port fiber command to configure it as auto or optical interface.

   If the interface type is set to auto, check that the electrical interface is not Up. If the electrical interface is Up, remove the network cables and then install the optical module.

   <AC6605> system-view 
   Enter system view, return user view with Ctrl+Z 
   [AC6605] interface GigabitEthernet 0/0/24 
   [AC6605-GigabitEthernet0/0/24] combo-port fiber

4. Run the display transceiver command to check whether any alarms about the optical module have been generated. If such alarms are displayed, handle the problem according to the alarms. For example, if an alarm shows that the receive signal strength is too high, use an optical attenuator between the remote optical module and the optical fiber.

   <AC6605> display transceiver interface gigabitethernet 0/0/24 verbose 
   GigabitEthernet0/0/24 transceiver information: 
   ------------------------------------------------------------- 
   Common information: 
     Transceiver Type               :OC3_INTER_REACH_SFP 
     Connector Type                 :LC 
     Wavelength(nm)                 :1310 
     Transfer Distance(m)           :15000(9um) 
     Digital Diagnostic Monitoring  :YES 
     Vendor Name                    :HUAWEI 
     Vendor Part Number             :34060358 
     Ordering Name                  : 
   ------------------------------------------------------------- 
   Manufacture information: 
     Manu. Serial Number            :EH1048220807 
     Manufacturing Date             :2010-12-06 
     Vendor Name                    :HUAWEI 
   ------------------------------------------------------------- 
   Alarm information: 
     RX loss of signal 
     RX power low 
   ------------------------------------------------------------- 
   Diagnostic information: 
     Temperature(°C)              :26.00 
     Temp High Threshold(°C)      :85.00 
     Temp Low  Threshold(°C)      :-40.00 
     Voltage(V)                    :3.29 
     Volt High Threshold(V)        :3.64 
     Volt Low  Threshold(V)        :2.95 
     Bias Current(mA)              :4.57 
     Bias High Threshold(mA)       :9.00 
     Bias Low  Threshold(mA)       :2.00 
     RX Power(dBM)                 :-40.00 
     RX Power High Threshold(dBM)  :0.00 
     RX Power Low  Threshold(dBM)  :-16.99 
     TX Power(dBM)                 :-5.03 
     TX Power High Threshold(dBM)  :-2.22 
     TX Power Low  Threshold(dBM)  :-6.99 
   -------------------------------------------------------------

   The attenuation coefficients of single-mode fibers with 1310 nm and 1550 nm wavelengths are 0.4 dB/km and 0.25 dB/km respectively.

5. If the interface remains Down, contact technical support personnel.