Configuring Wireless High Availability

Finding Feature Information

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Information about High Availability

The high availability feature is enabled by default when the devices are connected using the stack cable and the Cisco StackWise-480 technology is enabled. You cannot disable it; however, you can initiate a manual graceful-switchover using the command line interface to use the high availability feature enabled in the .

In Cisco Wireless LAN Controllers, high availability is achieved with redundancy.

In Cisco Wireless LAN Controllers, redundancy is achieved in two ways— n+1 and AP SSO redundancy.

Keepalive messages are sent and received between the active and standby controllers.

  • If the standby controller does not respond, a new standby controller is elected.

  • If the active controller does not respond, the standby controller becomes the active controller.

In addition, hello messages are sent and received by all stack members.

  • If a stack member does not respond, that member is removed from the stack.

  • If the standby controller does not respond, a new standby controller is elected.

  • If the active controller does not respond, the standby controller becomes the active controller.

Information About Redundancy

In case of n+1 redundancy, access points are configured with primary, secondary, and tertiary controllers. When the primary controller fails, depending upon the number of access points managed by a controller, the access point fails over to the secondary controller. In case of AP SSO redundancy, once the primary controller is unavailable, the access points re-discovers the controller and reestablishes the CAPWAP tunnel with the secondary controller. However, all clients must disconnect and a re-authentication is performed to rejoin the controller.

You can configure primary, secondary, and tertiary controllers for a selected access point and a selected controller.

In an ideal high availability deployment, you can have access points connected to primary and secondary controllers and one controller can remain with out connection to any access points. This way the controller that does not have any access points can take over when a failure occurs and resume services of active controller.

Configuring Redundancy in Access Points

You must use the commands explained in this section to configure primary, secondary, or tertiary controllers for a selected access point.

Before You Begin

SUMMARY STEPS

    1.    conf t

    2.    ap capwap backup primary

    3.    ap capwap backup secondary

    4.    ap capwap backup tertiary


DETAILED STEPS
     Command or ActionPurpose
    Step 1conf t

    Example: 
    Controller # conf t
     

    Configures the terminal

     
    Step 2 ap capwap backup primary

    Example: 
    Controller # ap capwap backup primary WLAN-Controller-A
     

    Configures the primary controller for the selected access point.

     
    Step 3 ap capwap backup secondary


    Example: 
    Controller # ap capwap backup secondary WLAN-Controller-B
     

    Configures the secondary controller for the selected access point.

     
    Step 4 ap capwap backup tertiary

    Example: 
    Controller # ap capwap backup tertiary WLAN-Controller-C
     

    Configures the tertiary controller for the selected access point.

     
    What to Do Next

    Once you complete configuration of the primary, secondary, and tertiary controllers for a selected access point, you must verify the configuration using the show ap name AP-NAME command. For more details on, show ap name AP-NAME command, see the Lightweight Access Point Configuration Guide for Cisco Wireless LAN Controller.

    Configuring Heartbeat Messages

    Hearbeat messages enable you to reduce the controller failure detection time. When a failure occurs, a switchover from active to hot standby happens after the controller waits for the heartbeat timer. If the controller does not function within the heartbeat time, then the standby takes over as then active controller. Ideally the access point generates three heartbeat messages within the time out value specified, and when the controller does not respond within the timeout value, the standby controller takes over as active. You can specify the timeout value depending on your network. Ideally the timer value is not a higher value as some chaos will occur while performing a switchover. This section explains on how to configure heartbeat interval between the controller and the access points using a timeout value to reduce the controller failure detection time.

    Before You Begin

    SUMMARY STEPS

      1.    conf t

      2.    ap capwap timers heartbeat-timeout


    DETAILED STEPS
       Command or ActionPurpose
      Step 1 conf t

      Example: 
      controller # conf t
       

      Configures the terminal.

       
      Step 2 ap capwap timers heartbeat-timeout

      Example: 
      controller #  ap capwap timers heartbeat-timeout
       

      Configures the heartbeat interval between the controller and access points. The timeout value ranges from 1 to 30.

       

      Information about Access Point Stateful Switch Over

      An Access Point Stateful Switch Over (AP SSO) implies that all the access point sessions are switched over state-fully and the user session information is maintained during a switchover, and access points continue to operate in network with no loss of sessions, providing improved network availability. The active in the stack is equipped to perform all network functions, including IP functions and routing information exchange. The supports 1000 access points and 12000 clients.

      However, all the clients are de-authenticated and need to be re-associated with the new active except for the locally switched clients in FlexConnect mode when a switchover occurs.

      Once a redundancy pair is formed while in a stack, high availability is enabled, which includes that access points continue to remain connected during an active-to-standby switchover.


      Note
      You can not disable AP SSO while in a stack once the devices form a redundant pair.

      Note

      After switchover new standby gets reloaded during stack formation, this is due to bulk sync failure. This is seen after reload, 2nd attempt to form stack successfully. This happens when you execute the command exception dump device second flash which is used to enable, dump crashfile on flash when crashinfo directory is full. When crash occurs and if there is no space left in crashinfo, it proceeds to store the fullcore or crash files into flash.

      Initiating Graceful Switchover

      To perform a manual switchover and to use the high availability feature enabled in the , execute the redundancy force-switchover command. This command initiates a graceful switchover from the active to the standby . 

      Device# redundancy force-switchover
System configuration has been modified. Save ? [yes/no] : yes
Building configuration …
Preparing for switchover …
Compressed configuration from 14977 bytes to 6592 bytes[OK]This will reload the active unit and force switchover to standby[confirm] : y

      Configuring EtherChannels for High Availability

      The LAG, or an EtherChannel, bundles all the existing ports in both the standby and active units into a single logical port to provide an aggregate bandwidth of 60 Gbps. The creation of an EtherChannel enables protection against failures. The EtherChannels or LAGs created are used for link redundancy to ensure high availability of access points.

      For more details on configuring EtherChannel, and Etherchannel modes, see the Layer 2 (Link Aggregation) Configuration Guide, Cisco IOS XE Release 3SE (Cisco WLC 5700 Series)

        Step 1   Connect two devices that are in powered down state using the stack cable.
        Step 2   Power up and perform a boot on both devices simultaneously or power and boot one .

        The devices boot up successfully, and form a high availability pair.

        Step 3   Configure EtherChannel or LAG on the units.
        Step 4   Use the show etherchannel summary command to view the status of the configured EtherChannel.

        On successful configuration, all the specified ports will be bundled in a single channel and listed in the command output of show etherchannel summary.

        Step 5   Execute the show ap uptime command to verify the connected access points.

        Configuring LACP

        SUMMARY STEPS

          1.    configure terminal

          2.    interface port-channel number

          3.    lacp max-bundle number

          4.    lacp port-priority number

          5.    switchport backup interface po2

          6.    end

          7.    show etherchannel summary

          8.    show interfaces switchport backup


        DETAILED STEPS
           Command or ActionPurpose
          Step 1configure terminal


          Example: 
          Device# configure terminal
                      		Enters global configuration mode.  
          Step 2interface port-channel number


          Example: 
          Device(config)# interface Port-channel Po2
                      		Enters port-channel interface configuration mode.  
          Step 3 lacp max-bundle number


          Example: 
          Device(config-if)# lacp max-bundle 6
           

          Defines the maximum number of active bundled LACP ports allowed in a port channel. The value ranges from 1 to 8.

           
          Step 4 lacp port-priority number


          Example: 
          Device(config-if)# lacp port-priority 4
           

          Specifies port priority to be configured on the port using LACP. The value ranges from 0 to 65535.

           
          Step 5 switchport backup interface po2


          Example: 
          Device(config-if)# switchport backup interface Po2
           

          Specifies an interface as the backup interface.

           
          Step 6end
                      		Exits the interface and configuration mode.  
          Step 7 show etherchannel summary


          Example: 
          Device# show etherchannel summary
           

          Displays a summary of EtherChannel properties.

           
          Step 8 show interfaces switchport backup


          Example: 
          Device# show interfaces switchport backup
           

          Displays summary of backup EtherChannel properties.

           

          Troubleshooting High Availability

          Access the Standby Console

          You can only access the console of the active in a stack. To access the standby , use the following commands.

          Before You Begin

          Use this functionality only under supervision of Cisco Support.

          SUMMARY STEPS

            1.    configure terminal

            2.    service internal

            3.    redundancy

            4.    main-cpu

            5.    standby console enable

            6.    exit


          DETAILED STEPS
             Command or ActionPurpose
            Step 1configure terminal


            Example: 
            Device# configure terminal
                          		Enters global configuration mode.  
            Step 2 service internal


            Example: 
            Device(config)# service internal
             

            Enables Cisco IOS debug commands.

             
            Step 3redundancy


            Example: 
            Device(config)# redundancy
             

            Enters redundancy configuration mode.

             
            Step 4main-cpu


            Example: 
            Device(config)# main-cpu
             

            Enters the redundancy main configuration submode.

             
            Step 5standby console enable


            Example: 
            Device(config)# standby console enable
             

            Enables the standby console.

             
            Step 6exit


            Example: 
            Device(config)# exit
             

            Exits the configuration mode.

             

            Before a Switchover

            A switchover happens when the active fails; however, while performing a manual switchover, you can execute these commands to initiate a successful switchover:

            SUMMARY STEPS

              1.    show redundancy states

              2.    show switch detail

              3.    show platform ses states

              4.    show ap summary

              5.    show capwap detail

              6.    show dtls database-brief

              7.    show power inline


            DETAILED STEPS
               Command or ActionPurpose
              Step 1 show redundancy states


              Example: 
              Device# show redundancy states
               

              Displays the high availability role of the active and standby devices.

               
              Step 2show switch detail


              Example: 
              Device# show switch detail
               

              Display physical property of the stack. Verify if the physical states of the stacks are "Ready" or "Port".

               
              Step 3show platform ses states


              Example: 
              Device# show platform ses states
               

              Displays the sequences of the stack manager.

               
              Step 4show ap summary


              Example: 
              Device# show ap summary
               

              Displays all the access points in the active and standby devices.

               
              Step 5show capwap detail


              Example: 
              Device# show capwap detail
               

              Displays the details of the CAPWAP tunnel in the active and standby devices.

               
              Step 6show dtls database-brief


              Example: 
              Device# show dtls database-brief
               

              Displays DTLS details in the active and standby devices.

               
              Step 7show power inline


              Example: 
              Device# show power inline
               

              Displays the power on Ethernet power state.

              Note    When a failover occurs, the standby controller must be in a standby-hot state and the redundant port in a terminal state in SSO for successful switchover to occur.
               

              After a Switchover

              This section defines the steps that you must perform to ensure that successful switchover from the active to standby is performed. On successful switchover of the standby as active, all access points connected to the active need to re-join the standby (then active) .

              SUMMARY STEPS

                1.    show ap uptime

                2.    show wireless summary

                3.    show wcdb database all

                4.    show power inline


              DETAILED STEPS
                 Command or ActionPurpose
                Step 1show ap uptime


                Example: 
                Device# show ap uptime
                 

                Verify if the uptime of the access point after the switchover is large enough.

                 
                Step 2show wireless summary


                Example: 
                Device# show wireless summary
                 

                Display the clients connected in the active .

                 
                Step 3show wcdb database all


                Example: 
                Device# show wcdb database all
                 

                Display if the client has reached the uptime.

                 
                Step 4show power inline


                Example: 
                Device# show power inline
                 

                Display the power over Ethernet power state.

                 

                Monitoring the Device Stack

                Table 1 Commands for Displaying Stack Information

                Command

                Description

                show switch

                Displays summary information about the stack, including the status of provisioned switches and switches in version-mismatch mode.

                show switch stack-member-number

                Displays information about a specific member.

                show switch detail

                Displays detailed information about the stack.

                show switch neighbors

                Displays the stack neighbors.

                show switch stack-ports [summary]

                Displays port information for the stack. Use the summary keyword to display the stack cable length, the stack link status, and the loopback status.

                show redundancy

                Displays the redundant system and the current processor information. The redundant system information includes the system uptime, standby failures, switchover reason, hardware, configured and operating redundancy mode. The current processor information displayed includes the active location, the software state, the uptime in the current state and so on.

                show redundancy state

                Displays all the redundancy states of the active and standby devices.

                LACP Configuration: Example

                This example shows how to configure LACP and to verify creation of the LACP bundle and the status: 

                Device(config)# !
interface TenGigabitEthernet1/0/1
 switchport mode trunk
 channel-group 1 mode active
 lacp port-priority 10
 ip dhcp snooping trust
!
interface TenGigabitEthernet1/0/2
 switchport mode trunk
 channel-group 1 mode active
 lacp port-priority 10
 ip dhcp snooping trust
!
interface TenGigabitEthernet1/0/3
 switchport mode trunk
 channel-group 1 mode active
 lacp port-priority 10
 ip dhcp snooping trust
!
interface TenGigabitEthernet1/0/4
 switchport mode trunk
 channel-group 1 mode active
 ip dhcp snooping trust
!
interface TenGigabitEthernet1/0/5
 switchport mode trunk
 channel-group 1 mode active
 ip dhcp snooping trust
!
interface TenGigabitEthernet1/0/6
 switchport mode trunk
 channel-group 1 mode active
 ip dhcp snooping trust
!
interface TenGigabitEthernet2/0/1
 switchport mode trunk
 channel-group 1 mode active
 lacp port-priority 10
 ip dhcp snooping trust
!
interface TenGigabitEthernet2/0/2
 switchport mode trunk
 channel-group 1 mode active
 lacp port-priority 10
 ip dhcp snooping trust
!
interface TenGigabitEthernet2/0/3
 switchport mode trunk
 channel-group 1 mode active
 lacp port-priority 10
 ip dhcp snooping trust
!
interface TenGigabitEthernet2/0/4
 switchport mode trunk
 channel-group 1 mode active
 ip dhcp snooping trust
!
interface TenGigabitEthernet2/0/5
 switchport mode trunk
 channel-group 1 mode active
 ip dhcp snooping trust
!
interface TenGigabitEthernet2/0/6
 switchport mode trunk
 channel-group 1 mode active
 ip dhcp snooping trust
!
interface Vlan1
 no ip address
 ip igmp version 1
 shutdown
!

Device#  show etherchannel summary
		 
		Flags:  D - down        P - bundled in port-channel
        I - stand-alone s - suspended
        H - Hot-standby (LACP only)
        R - Layer3      S - Layer2
        U - in use      f - failed to allocate aggregator

        M - not in use, minimum links not met
        u - unsuitable for bundling
        w - waiting to be aggregated
        d - default port


Number of channel-groups in use: 1
Number of aggregators:           1

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
1      Po1(SU)         LACP      Te1/0/1(P)  Te1/0/2(P)  Te1/0/3(P)
                                 Te1/0/4(H)  Te1/0/5(H)  Te1/0/6(H)
                                 Te2/0/1(P)  Te2/0/2(P)  Te2/0/3(P)
                                 Te2/0/4(H)  Te2/0/5(H)  Te2/0/6(H)

                This example shows the switch backup interface pairs: 

                Device# show interfaces switchport backup

Switch Backup Interface Pairs:

Active Interface        Backup Interface        State
------------------------------------------------------------------------
Port-channel1             Port-channel2             Active Standby/Backup Up

                This example shows the summary of the EtherChannel configured in the : 

                Device# show ethernet summary

Flags:  D - down        P - bundled in port-channel
        I - stand-alone s - suspended
        H - Hot-standby (LACP only)
        R - Layer3      S - Layer2
        U - in use      f - failed to allocate aggregator

        M - not in use, minimum links not met
        u - unsuitable for bundling
        w - waiting to be aggregated
        d - default port


Number of channel-groups in use: 2
Number of aggregators:           2

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
1      Po1(SU)         LACP      Te1/0/1(P)  Te1/0/2(P)  Te1/0/3(P)
                                 Te1/0/4(P)  Te1/0/5(P)  Te1/0/6(P)
2      Po2(SU)         LACP      Te2/0/1(P)  Te2/0/2(P)  Te2/0/3(P)
                                 Te2/0/4(P)  Te2/0/5(P)  Te2/0/6(P)