PoE: The AC Cannot Supply PoE to APs

Symptom

The AC cannot supply PoE to APs.

Possible Causes

• The AC power module does not support the PoE function.
• The PoE configuration on the AC is incorrect.
• A fault occurs on the intermediate link, such as a network cable fault.

Procedure

1. Collect information about the AC and APs, including the AC model, AP model, network cable type, network cable length, and commands used on the AC.

   <AC> display version                   //Display the AC version.
   <AC> display device                    //Display the type and status of components on the device.
   <AC> display elabel                    //Display the electronic label of the device.
   <AC> display poe device                //Display information about the PoE-capable device.
   <AC> display poe information           //Display PoE running information on the device.
   <AC> display poe power                 //Display current power information on ports.
   <AC> display poe power-state           //Display the PoE power supply status of the device.
   <AC> display poe power-state interface gigabitethernet 0/0/3             //Display the PoE power supply status of a specified port.
   <AC> display logbuffer                 //Display information recorded in the log buffer.
   <AC> display trapbuffer                //Display information recorded in the trap buffer.
   <AC> display alarm history             //Display historical alarms on the AC.
   <AC> save logfile                    //Save logs in the log buffer to a log file and export the log file.

2. Check whether the power module supports the PoE function and whether the power module is properly working.
   1. Check whether the power module supports PoE.
      • Observe the appearance of the power module.

        The 150 W DC power module (part number: 02310JFD) and 150 W AC power module (part number: 02310JFA) of the AC6605 do not support PoE power supply.

        The 500 W AC power module (part number: 02130983) of the AC6605 supports PoE power supply.

      • Check the bar code on the power module.

        If the bar code of the power module starts with 2102130983, it is a 500 W AC PoE power module of the AC.

      • Check the electronic label of the power module.

        Log in to the AC and run the following command:

        <AC> display elabel

        The following information is displayed:

        [Board Properties]                                                              
        BoardType=W2PSA0500                                                             
        BarCode=21021309838NCB000181                                                    
        Item=02130983
        Description=AC/DC power module--25degC-55degC-90V-264V-12V/10A,-53.5V/7.1A      
        Manufactured=2012-11-25                                                         
        VendorName=Huawei                                                               
        IssueNumber=                                                                    
        CLEICode=                                                                       
        BOM=

        If the Item field is 02130983, the power module is a PoE power module.

   2. Check whether the power module is faulty.

      Check the status of indicators on a 500 W power module (part number: 02130983).

      Indicator	Status	Description
      INPUT	Steady green	The input power is within the normal range.
      	Steady red	The input power is out of the normal range, which may be caused by the following reasons: Undervoltage Overvoltage
      	Off	The power cable is loose or no AC power input is available.
      OUTPUT	Steady green	The AC output power is within the normal range.
      	Steady red	The output power is out of the normal range, which may be caused by the following reasons: Failure of fans in the power module Output overvoltage Output current limit Output short circuit Overtemperature protection
      	Off	The power cable is loose or no AC power input is available.

   Technical support personnel need to check for records of power module faults in the log file on the AC.

3. Check and adjust the PoE configuration on the AC.

   Run the following command in the system view (GE0/0/3 is used as an example):

   <AC> display poe power-state interface gigabitethernet 0/0/3

   If the Port power enabled field is Disable, enable the PoE function in the interface view.

   Check whether the fault is rectified.

4. Check whether the physical layer (for example, network cables and distribution frames) between the AP and AC is working properly.
   1. Perform a cross test to check whether network cables between the AP and AC are faulty.
   2. Check whether the network cables comply with PoE standards.

      A network cable tester or multimeter is typically used to check network cable quality.

      Network cable quality required by PoE standards

      Standard		Total Resistance of a Network Cable
      802.3af		≤ 20 ohms
      802.3at	Type 1	≤ 20 ohms
      	Type 2	≤ 12.5 ohms

      The resistance of a network cable can be tested using the following methods:

      • Method 1: Use a network cable tester to test the resistance of a network cable.
      • Method 2: Connect test probes of a multimeter to the two ends of each network cable, and read the resistance value of the network cable on the multimeter. The cable resistance approximately equals the displayed value.
      • Method 3: Connect a network cable to an AP. Use a multimeter to test the resistance between pins 1 and 2 of the cable (or between pins 3 and 6, 4 and 5, or 7 and 8). The cable resistance approximately equals half of the displayed value.

      If the resistance of a network cable does not meet requirements of PoE standards, replace the network cable.

   3. The distribution frame is often used on the live network, and RJ45 connectors may be loosely inserted on the distribution frame. Perform a cross test to verify that cable connections on the distribution frame are normal.

5. Use the forcible power-on commands.

   The forcible power-on commands provide the following functions:

   1. Forcibly power on a PoE interface.

      <AC> system-view
      [AC] interface gigabitethernet 0/0/1
      [AC-Ethernet0/0/1] poe force-power
      Warning: Is there a valid PD connected to this interface? Yes or No?[Y/N]:y

   2. Configure the device to allow high inrush current during power-on.

      <AC> system-view
      [AC] poe high-inrush enable

   3. Enable a port (for example, GE0/0/1) to check the compatibility of PDs.

      <AC> system-view
      [AC] interface gigabitethernet 0/0/1
      [AC-Ethernet0/0/1] poe legacy enable

6. Perform a cross test to check whether an AP is faulty.

   Use a new AP or connect the network cable to a properly working AP. Check whether the AP can be powered on.

   • If so, rectify the fault by referring to Device Power-On: An AP Cannot Be Powered On or Fails to Start After Power-On.
   • If not, check the network cable again, or restart the AC if allowed and check whether the AC is properly grounded. Contact technical support personnel.