Failed to Set Up Dual Links

Symptom

Dual links cannot be set up between the active and standby ACs.

Possible Causes

• The dual-link backup function is disabled on the active AC.
• The IP address of the standby AC is not configured on the active AC or the configured IP address of the standby AC is different from the actual one.
• The standby AC is not started properly.
• The dual-link backup function is disabled on the standby AC.
• The IP address of the standby AC is not configured.
• The active AC is not started properly when the AP is selecting an active AC.

Procedure

1. Check whether the dual-link backup function is enabled on the active AC.
   • If so, go to step 2.
   • If not, enable the dual-link backup function.

     Run the display wlan ac protect command on the active AC, and check whether the dual-link backup function is enabled. If not, run the ac protect enable command to enable the dual-link backup function.

     [AC20] display ac protect
     ------------------------------------------------------------ 
     Protect state             : disable
     Protect AC                : -
     Priority                  : 0
     Protect restore           : enable
     Coldbackup kickoff station: disable 
     ------------------------------------------------------------

2. Check whether the IP address of the standby AC configured on the active AC is correct.
   1. Check the configured IP address of the standby AC on the active AC by referring to step 1.
   2. Check the actual IP address of the standby AC.

      Run the display capwap configuration command on the standby AC to check the IP address. If an IP address is configured as the source IP address is an IP address, the IP address is directly displayed. If a VLANIF address is configured as the source interface, the IP address of the VLANIF address is displayed.

      [AC20] display capwap configuration 
        ------------------------------------------------------------ 
        Source interface                            : - 
        Source ip-address                           : 10.1.1.111 
        Echo interval(seconds)                      : 25
        Echo times                                  : 6
        Control priority(server to client)          : 7
        Control priority(client to server)          : 7
        Control-link DTLS encrypt                   : disable
        DTLS PSK value                              : ******
        PSK mandatroy match switch                  : enable 
        Control-link inter-controller DTLS encrypt  : disable 
        Inter-controller DTLS PSK value             : ****** 
        IPv6 status                                 : disable
        ------------------------------------------------------------

   3. Check whether the IP addresses in 2.a and 2.b are the same.
      • If so, go to step 3.
      • If not, change the configured IP address of the standby AC on the active AC.

3. Check whether the standby AC functions properly.

   If the standby AC is faulty, the AP fails to go online on the standby AC when the active AC is faulty.

   • If the standby AC works properly, go to step 4.
   • If the standby AC does not work properly, troubleshoot the fault based on the actual situation.

4. Check whether the dual-link backup function is enabled on the standby AC by referring to step 1.
   • If so, go to step 5.
   • If not, enable the dual-link on the standby AC.

5. Check whether the IP address of the standby AC is configured.
   • If so, go to 6.
   • If not, the standby AC does not send dual-link information to the AP during the link setup. As a result, dual links cannot be set up. Configure the IP address of the standby AC by referring to 2.

6. Collect the following information and contact technical support personnel:
   • Results of the preceding troubleshooting procedure
   • Configuration file, logs, and alarms of the device