Configuring the SwitchController for Access Point Discovery

Finding Feature Information

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Prerequisites for Configuring the SwitchController for Access Point Discovery

  • Ensure that the Control and Provisioning of Wireless Access Points (CAPWAP) UDP ports 5246 and 5247 (similar to the Lightweight Access Point Protocol (LWAPP) UDP ports 12222 and 12223) are enabled and are not blocked by an intermediate device that could prevent an access point from joining the switchcontroller.

  • If access control lists (ACLs) are in the control path between the switchcontroller and its access points, you must open new protocol ports to prevent access points from being stranded.

  • If an access point is in the UP state and its IP address changes, the access point tears down the existing CAPWAP tunnel and rejoins the switchcontroller.

  • Access points must be discovered by a switchcontroller before they can become an active part of the network. The lightweight access points support the following switchcontroller discovery processes:

    • Layer 3 CAPWAP discovery—You can enable this feature on different subnets from the access point. This feature uses IP addresses and UDP packets rather the MAC addresses used by Layer 2 discovery.

    • Locally stored switchcontroller IP address discovery—If the access point was previously associated to a switchcontroller, the IP addresses of the primary, secondary, and tertiary switchcontrollers are stored in the access point’s nonvolatile memory. This process of storing switchcontroller IP addresses on an access point for later deployment is called priming the access point.

    • DHCP server discovery—This feature uses DHCP option 43 to provide switchcontroller IP addresses to the access points. Cisco switches support a DHCP server option that is typically used for this capability.

    • DNS discovery—The access point can discover switchcontrollers through your domain name server (DNS). You must configure your DNS to return switchcontroller IP addresses in response to CISCO-CAPWAP-CONTROLLER.localdomain, where localdomain is the access point domain name. When an access point receives an IP address and DNS information from a DHCP server, it contacts the DNS to resolve CISCO-CAPWAP-CONTROLLER.localdomain. When the DNS sends a list of switchcontroller IP addresses, the access point sends discovery requests to the switchcontrollers.

Restrictions for Configuring the SwitchController for Access Point Discovery

  • Ensure that the switchcontrollers are configured with the correct date and time. If the date and time configured on the switchcontroller precedes the creation and installation date of certificates on the access points, the access point fails to join the switchcontroller.

  • During the discovery process, access points that are supported by the Cisco switchcontroller, such as the 1140, 1260, 3500, 1040,1600, 2600, or 3600 query only for Cisco switchcontrollers.

Information About Configuring the SwitchController for Access Point Discovery

In a CAPWAP environment, a lightweight access point discovers a switchcontroller by using CAPWAP discovery mechanisms and then sends a CAPWAP join request to the switchcontroller. The switchcontroller sends a CAPWAP join response to the access point that allows the access point to join the switchcontroller. When the access point joins the switchcontroller, the switchcontroller manages its configuration, firmware, control transactions, and data transactions.

Access Point Communication Protocols

Cisco lightweight access points use the IETF standard CAPWAP to communicate with the switchcontroller and other lightweight access points on the network.

CAPWAP, which is based on LWAPP, is a standard, interoperable protocol that enables a switchcontroller to manage a collection of wireless access points. CAPWAP is implemented in switchcontroller for these reasons:

  • To provide an upgrade path from Cisco products that use LWAPP to next-generation Cisco products that use CAPWAP

  • To manage RFID readers and similar devices

  • To enable switchcontrollers to interoperate with third-party access points in the future

Viewing Access Point Join Information

Join statistics for an access point that sends a CAPWAP discovery request to the switchcontroller at least once are maintained on the switchcontroller even if the access point is rebooted or disconnected. These statistics are removed only when the switchcontroller is rebooted or when you choose to clear the statistics.

Troubleshooting the Access Point Join Process

Access points can fail to join a switchcontroller for many reasons such as a RADIUS authorization is pending, self-signed certificates are not enabled on the switchcontroller, the access point and switchcontroller’s regulatory domains do not match, and so on.

You can configure the access points to send all CAPWAP-related errors to a syslog server. You do not need to enable any debug commands on the switchcontroller because all of the CAPWAP error messages can be viewed from the syslog server itself.

The state of the access point is not maintained on the switchcontroller until it receives a CAPWAP join request from the access point, so it can be difficult to determine why the CAPWAP discovery request from a certain access point was rejected. In order to troubleshoot such joining issues without enabling CAPWAP debug commands on the switchcontroller, the switchcontroller collects information for all access points that send a discovery message to this switchcontroller and maintains information for any access points that have successfully joined this switchcontroller.

The switchcontroller collects all join-related information for each access point that sends a CAPWAP discovery request to the switchcontroller. Collection begins when the first discovery message is received from the access point and ends when the last configuration payload is sent from the switchcontroller to the access point.

When the switchcontroller is maintaining join-related information for the maximum number of access points, it does not collect information for any more access points.

You can also configure a DHCP server to return a syslog server IP address to the access point using option 7 on the server. The access point then starts sending all syslog messages to this IP address.

You can configure the syslog server IP address through the access point CLI, if the access point is not connected to the switchcontroller by entering the capwap ap log-server syslog_server_IP_address command.

When the access point joins a switchcontroller for the first time, the switchcontroller pushes the global syslog server IP address (the default is 255.255.255.255) to the access point. After that, the access point sends all syslog messages to this IP address, until it is overridden by one of the following scenarios:

  • The access point is still connected to the same switchcontroller, and you changed the global syslog server IP address configuration on the switchcontroller by using the ap syslog host Syslog_Server_IP_Address command. In this case, the switchcontroller pushes the new global syslog server IP address to the access point.

  • The access point is still connected to the same switchcontroller, and you configured a specific syslog server IP address for the access point on the switchcontroller by using the ap name Cisco_AP syslog host Syslog_Host_IP_Address command. In this case, the switchcontroller pushes the new specific syslog server IP address to the access point.

  • The access point gets disconnected from the switchcontroller, and you configured the syslog server IP address from the access point CLI by using the capwap ap log-server syslog_server_IP_address command. This command works only if the access point is not connected to any switchcontroller.

  • The access point gets disconnected from the switchcontroller and joins another switchcontroller. In this case, the new switchcontroller pushes its global syslog server IP address to the access point.

Whenever a new syslog server IP address overrides the existing syslog server IP address, the old address is erased from persistent storage, and the new address is stored in its place. The access point also starts sending all syslog messages to the new IP address, if the access point can reach the syslog server IP address.

How to Configure Access Point Discovery

Configuring the Syslog Server for Access Points (CLI)

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    ap syslog host host_ip_address

    4.    end

    5.    show ap config global

    6.    show ap name Cisco_AP config general


DETAILED STEPS
     Command or ActionPurpose
    Step 1 enable


    Example: 
    Switch# enable
     

    Enters privileged EXEC mode.

     
    Step 2 configure terminal


    Example: 
    Switch# configure terminal
     

    Enters global configuration mode.

     
    Step 3 ap syslog host host_ip_address


    Example: 
    Switch(config)# ap syslog host
 10.9.9.16
     

    Configures the global syslog server for all access points that join this switchcontroller.

    Note   

    By default, the global syslog server IP address for all access points is 255.255.255.255. Make sure that the access points can reach the subnet on which the syslog server resides before configuring the syslog server on the switchcontroller. If the access points cannot reach this subnet, the access points are unable to send out syslog messages.

     
    Step 4end


    Example:
    Switch(config)# end
     

    Returns to privileged EXEC mode. Alternatively, you can also press Ctrl-Z to exit global configuration mode.

     
    Step 5show ap config global


    Example:
    Switch# show ap config global
     

    Displays the global syslog server settings for all access points that join the switchcontroller.

     
    Step 6show ap name Cisco_AP config general


    Example:
    Switch# show ap name AP03 config general
     

    Displays the syslog server settings for a specific access point.

     

    Monitoring Access Point Join Information (CLI)


    Note

    The procedure to perform this task using the switchcontroller GUI is not currently available.

    SUMMARY STEPS

      1.    enable

      2.    show ap join stats summary

      3.    show ap mac-address mac_address join stats summary

      4.    show ap mac-address mac_address join stats detailed

      5.    clear ap join statistics


    DETAILED STEPS
       Command or ActionPurpose
      Step 1 enable


      Example: 
      Switch# enable
       

      Enters privileged EXEC mode.

       
      Step 2 show ap join stats summary


      Example: 
      Switch# show ap join stats summary
       

      Displays the MAC addresses of all the access points that are joined to the switchcontroller or that have tried to join.

       
      Step 3show ap mac-address mac_address join stats summary


      Example: 
      Switch# show ap mac-address
 000.2000.0400 join stats summary
       

      Displays all the statistics for the AP including the last join error detail.

       
      Step 4show ap mac-address mac_address join stats detailed


      Example: 
      Switch# show ap mac-address
 000.2000.0400 join stats detailed
       

      Displays all join-related statistics collected for a specific access point.

       
      Step 5clear ap join statistics


      Example: 
      Switch# clear ap join statistics
       
      Clears the join statistics for all access points.
      Note   

      To clear the join statistics that correspond to specific access points, enter the clear ap mac-address mac_address join statistics command.

       

      Searching for Access Point Radios (GUI)

        Step 1   Choose Monitor > Wireless > Access Points and click 802.11a/n/ac Statistics or 802.11b/g/n Statistics.

        The 802.11 Radio pages are displayed. These pages show all of the 802.11a/n/ac or 802.11b/g/n access point radios that are associated with the switchcontroller and their current settings.

        Note   

        In a Cisco converged access environment, the 802.11a/n/ac and 802.11b/g/n radios should not be differentiated based on their Base Radio MAC addresses, because they might have the same addresses. Instead, the radios should be differentiated based on their physical addresses.

        Step 2   From the Show drop-down list, choose Quick Filter.

        The filter options (text boxes) appear in each of the column header in the table.

        Step 3   Enter a keyword in the corresponding text boxes to specify the filter criteria based on which you want to search, and click the Filter icon.

        Monitoring the Interface Details (GUI)

          Step 1   Choose Configuration > Wireless > Access Points > All APs.

          The All APs page is displayed showing a list of access points that are associated with the switchcontroller.

          Step 2   Click the access point name.

          The AP > Edit page is displayed.

          Step 3   Click the Interface tab.

          The interface details are displayed.

          Configuration Examples for Configuring the SwitchController for Access Point Discovery

          Displaying the MAC Addresses of all Access Points: Example

          This example shows how to display MAC addresses of all the access points that are joined to the switchcontroller:

          Switch# show ap join stats summary
Number of APs.......................................... 4

Base Mac          EthernetMac       AP Name IP Address    Status
----------------- ----------------- ------- ------------- ----------
00:0b:85:57:bc:c0 00:0b:85:57:bc:c0 AP1130  10.10.163.217 Joined
00:1c:0f:81:db:80 00:1c:63:23:ac:a0 AP1140  10.10.163.216 Not joined
00:1c:0f:81:fc:20 00:1b:d5:9f:7d:b2 AP1     10.10.163.215 Joined
00:21:1b:ea:36:60 00:0c:d4:8a:6b:c1 AP2     10.10.163.214 Not joined

          This example shows how to display the last join error details for a specific access point:

          Switch# show ap mac-address 000.2000.0400 join stats summary
Is the AP currently connected to controller................ Yes
Time at which the AP joined this 
controller last time................................. Aug 21 12:50:36.061
Type of error
that occurred last.................. AP got or has been disconnected
Reason for error 
that occurred last........... The AP has been reset by the controller
Time at which the last join error occurred......... Aug 21 12:50:34.374

          This example shows how to display all join-related statistics collected for a specific access point:

          Switch# show ap mac-address 000.2000.0400 join stats detailed
Discovery phase statistics
- Discovery requests received........................ 2
- Successful discovery responses sent................ 2
- Unsuccessful discovery request processing.......... 0
- Reason for last unsuccessful discovery attempt..... Not applicable
- Time at last successful discovery attempt.......... Aug 21 12:50:23.335
- Time at last unsuccessful discovery attempt........ Not applicable

Join phase statistics
- Join requests received............................. 1
- Successful join responses sent..................... 1
- Unsuccessful join request processing............... 1
- Reason for last unsuccessful join attempt.....      RADIUS authorization
                                                      is pending
                                                      for the AP
- Time at last successful join attempt............... Aug 21 12:50:34.481
- Time at last unsuccessful join attempt............. Aug 21 12:50:34.374

Configuration phase statistics
- Configuration requests received..................... 1
- Successful configuration responses sent............. 1
- Unsuccessful configuration request processing....... 0
- Reason for last unsuccessful configuration attempt.. Not applicable
- Time at last successful configuration attempt....... Aug 21 12:50:34.374
- Time at last unsuccessful configuration attempt..... Not applicable

Last AP message decryption failure details
- Reason for last message decryption failure.......... Not applicable

Last AP disconnect details
- Reason for last AP connection failure............... The AP has been reset by
                                                       the controller
Last join error summary
- Type of error that occurred last.................... AP got or has been
                                                       disconnected
- Reason for error that occurred last................. The AP has been reset
                                                       by the controller
- Time at which the last join error occurred.......... Aug 21 12:50:34.374

          DHCP Option 43 for Lightweight Cisco Aironet Access Points Configuration Example

          For more information about the AP join process, see DHCP OPTION 43 for Lightweight Cisco Aironet Access Points Configuration Example at http:/​/​www.cisco.com/​en/​US/​tech/​tk722/​tk809/​technologies_​configuration_​example09186a00808714fe.shtml.