WLAN Configuration Guide, Cisco IOS XE Release 3E (Catalyst 3850 Switches)
Configuring Assisted Roaming
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Configuring Assisted Roaming

Configuring Assisted Roaming

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.

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Restrictions for Assisted Roaming

  • The assisted roaming feature is supported across multiple switches.
  • This feature is supported only on 802.11n capable indoor access points. For a single band configuration, a maximum of 6 neighbors are visible in a neighbor list. For dual band configuration, a maximum of 12 neighbors are visible.
  • You can configure assisted roaming only using the switch CLI.

Information About Assisted Roaming

The 802.11k standard allows clients to request neighbor reports containing information about known neighbor access points that are candidates for a service set transition. The use of the 802.11k neighbor list can limit the need for active and passive scanning.

The assisted roaming feature is based on an intelligent and client optimized neighbor list.

Unlike the Cisco Client Extension (CCX) neighbor list, the 802.11k neighbor list is generated dynamically on-demand and is not maintained on the switch. The 802.11k neighbor list is based on the location of the clients without requiring the mobility services engine (MSE). Two clients on the same switch but different APs can have different neighbor lists delivered depending on their individual relationship with the surrounding APs.

By default, the neighbor list contains only neighbors in the same band with which the client is associated. However, a switch exists that allows 802.11k to return neighbors in both bands.

Clients send requests for neighbor lists only after associating with the APs that advertize the RRM (Radio Resource Management) capability information element (IE) in the beacon. The neighbor list includes information about BSSID, channel, and operation details of the neighboring radios.

Assembling and Optimizing the Neighbor List

When the switch receives a request for an 802.11k neighbor list, the following occurs:
  1. The switch searches the RRM neighbor table for a list of neighbors on the same band as the AP with which the client is currently associated with.
  2. The switch checks the neighbors according to the RSSI (Received Signal Strength Indication) between the APs, the current location of the present AP, the floor information of the neighboring AP from Cisco Prime Infrastructure, and roaming history information on the switch to reduce the list of neighbors to six per band. The list is optimized for APs on the same floor.

Assisted Roaming for Non-802.11k Clients

It is also possible to optimize roaming for non-802.11k clients. You can generate a prediction neighbor list for each client without the client requiring to send an 802.11k neighbor list request. When this is enabled on a WLAN, after each successful client association/reassociation, the same neighbor list optimization is applied on the non-802.11k client to generate the neighbor list and store the list in the mobile station software data structure. Clients at different locations have different lists because the client probes are seen with different RSSI values by different neighbors. Because clients usually probe before any association or reassociation, this list is constructed with the most updated probe data and predicts the next AP that the client is likely to roam to.

We discourage clients from roaming to those less desirable neighbors by denying association if the association request to an AP does not match the entries on the stored prediction neighbor list.

Similar to aggressive load balancing, there is a switch to turn on the assisted roaming feature both on a per-WLAN basis and globally. The following options are available:
  • Denial count—Maximum number of times a client is refused association.
  • Prediction threshold—Minimum number of entries required in the prediction list for the assisted roaming feature to be activated.

Because both load balancing and assisted roaming are designed to influence the AP that a client associates with, it is not possible to enable both the options at the same time on a WLAN.

How to Configure Assisted Roaming

Configuring Assisted Roaming (CLI)

SUMMARY STEPS

    1.    configure terminal

    2.    wireless assisted-roaming floor-bias dBm

    3.    wlan wlan-id

    4.    assisted-roaming neighbor-list

    5.    assisted-roaming dual-list

    6.    assisted-roaming prediction

    7.    wireless assisted-roaming prediction-minimum count

    8.    wireless assisted-roaming denial-maximum count

    9.    end


DETAILED STEPS
     Command or ActionPurpose
    Step 1 configure terminal


    Example:
    Switch# configure terminal
     

    Enters global configuration mode.

     
    Step 2wireless assisted-roaming floor-bias dBm


    Example:
    Switch(config)# wireless assisted-roaming floor-bias 20
     

    Configures neighbor floor label bias. The valid range is from 5 to 25 dBm, and the default value is 15 dBm.

     
    Step 3wlan wlan-id


    Example:
    Switch(config)# wlan wlan1
     

    Enters the WLAN configuration submode. The wlan-name is the profile name of the configured WLAN.

     
    Step 4assisted-roaming neighbor-list


    Example:
    Switch(wlan)# assisted-roaming neighbor-list
     

    Configures an 802.11k neighbor list for a WLAN. By default, assisted roaming is enabled on the neighbor list when you create a WLAN. The no form of the command disables assisted roaming neighbor list.

     
    Step 5assisted-roaming dual-list


    Example:
    Switch(wlan)# assisted-roaming dual-list
     

    Configures a dual-band 802.11k dual list for a WLAN. By default, assisted roaming is enabled on the dual list when you create a WLAN. The no form of the command disables assisted roaming dual list.

     
    Step 6assisted-roaming prediction


    Example:
    Switch(wlan)# assisted-roaming prediction
     
    Configures assisted roaming prediction list feature for a WLAN. By default, the assisted roaming prediction list is disabled.
    Note   

    A warning message is displayed and load balancing is disabled for the WLAN if load balancing is already enabled for the WLAN.

     
    Step 7wireless assisted-roaming prediction-minimum count


    Example:
    Switch# wireless assisted-roaming prediction-minimum 
     
    Configures the minimum number of predicted APs required for the prediction list feature to be activated. The default value is 3.
    Note   

    If the number of the AP in the prediction assigned to the client is less than the number that you specify, the assisted roaming feature will not apply on this roam.

     
    Step 8wireless assisted-roaming denial-maximum count


    Example:
    Switch# wireless assisted-roaming denial-maximum 8
     

    Configures the maximum number of times a client can be denied association if the association request is sent to an AP does not match any AP on the prediction. The valid range is from 1 to 10, and the default value is 5.

     
    Step 9end


    Example:
    Switch(config)# end
     

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

     

    Monitoring Assisted Roaming

    The following command can be used to monitor assisted roaming configured on a WLAN. .

    Command Description
    show wlan id wlan-id

    Displays the WLAN parameters on the WLAN.

    Configuration Examples for Assisted Roaming

    This example shows how to configure the neighbor floor label bias:
    Switch# configure terminal
    Switch(config)# wireless assisted-roaming floor-bias 10
    Switch(config)# end
    Switch# show wlan id 23
    
    This example shows how to disable neighbor list on a specific WLAN:
    Switch# configure terminal
    Switch(config)# wlan test1
    Switch(config (wlan)# no assisted-roaming neighbor-list
    Switch(config)(wlan)# end
    Switch# show wlan id 23
    
    This example shows how to configure the prediction list on a specific WLAN:
    Switch# configure terminal
    Switch(config)# wlan test1
    Switch(config)(wlan)# assisted-roaming prediction
    Switch(config)(wlan)# end
    Switch# show wlan id 23
    
    This example shows how to configure the prediction list based on assisted roaming prediction threshold and maximum denial count on a specific WLAN:
    Switch# configure terminal
    Switch(config)# wireless assisted-roaming prediction-minimum 4
    Switch(config)# wireless assisted-roaming denial-maximum 4
    Switch(config)(wlan)# end
    Switch# show wlan id 23
    

    Additional References for Assisted Roaming

    Related Documents

    Related Topic Document Title
    System management commands

    System Management Command Reference (Catalyst 3850 Switches)

    Error Message Decoder

    Description Link

    To help you research and resolve system error messages in this release, use the Error Message Decoder tool.

    https:/​/​www.cisco.com/​cgi-bin/​Support/​Errordecoder/​index.cgi

    Standards and RFCs

    Standard/RFC Title
    802.11k

    MIBs

    MIB MIBs Link
    All supported MIBs for this release.

    To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

    http:/​/​www.cisco.com/​go/​mibs

    Technical Assistance

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    Feature History and Information For Performing Assisted Roaming Configuration

    Feature Name Release Feature Information

    Assisted Roaming

    Cisco IOS XE 3.2SE

    This feature was introduced.