LANCOM Systems Support KnowledgeBase - Support Information
Document No: 1407.2512.3717.RHOO

Client Steering steering with a LANCOM WLAN controller
Description:

Client steering enables the LANCOM access points to help WLAN clients located within transmission range to connect to the best suited access point.

The necessary criteria are specified centrally on the LANCOM WLAN controller. Managed access points constantly report their current values to the LANCOM WLAN controller, which uses these criteria to decide which access points may respond to requests from WLAN clients. For this reason, client steering is only possible with access points that are centrally managed by a WLAN controller.

Client steering is a component of the LANCOM Active Radio Control (ARC) Database 'SP Knowledgebase', View '03. Edit Documents\by Responsible, Status', Document 'LANCOM Active Radio Control (ARC)'.



Requirements:

  • Configured WLAN infrastructure, which is managed by a LANCOM WLAN controller.


1) How client steering works:




In managed networks a LANCOM WLC centralally controls the client steering for all of the access points connected to it. In this case, client steering works as follows:

1.1) The LANCOM WLC collects the data about the associated WLAN clients from the APs connected to it. These data are the basis for the WLC to control the client steering.

1.2) All of the access points are configured so that the client steering is carried out via the LANCOM WLC (see the procedure in Section 2).

1.3) An unassociated WLAN client sends a probe request to the access points within its range.

1.4) Using CAPWAP, the access points transmit the request and the signal strength of the WLAN client to the LANCOM WLC.

1.5) For each access point within range of the LANCOM WLAN client, the WLC calculates a value from three factors:
  • A value for signal strength
  • A value for the number of WLAN clients associated at the access point
  • A value for the frequency band

The LANCOM WLC weights these factors and multiplies them together to derive the final value.

1.6) Access points with the highest value, or a value that deviates from it within a specified tolerance level, receive a message from the LANCOM WLC that they may accept the WLAN client at the next login attempt.

1.7) If the WLAN client attempts to connect to an access point before the LANCOM WLC has responded, then the access point ignores the client's connection request until the response from the WLC has arrived.
    Information:
    If Voice-over-IP applications operated via the WLAN experience problems, we recommend that you disable the client steering.

1.8) If a WLAN client is being "sticky", i.e. it does not attempt to connect to another access point offering a better connection quality, the WLC can trigger the current access point to log off the WLAN client. The WLAN client is then forced to connect with the access point offering the better connection.
    Information:
    If an access point loses connection to the WLC which is responsible for client steering, the access point accepts all connections from authenticated WLAN clients.

2) Procedure:

2.1) Open the configuration of the LANCOM WLC in LANconfig and navigate to the menu Configuration -> WLAN controller -> Profiles -> Physical WLAN parameters.

2.2) Enable the client steering feature in the desired profile with the option On. The following parameters are also available:
  • Off: Client steering is deactivated.
  • AP-based band steering: The access point independently steers the WLAN client to a preferred frequency band.
  • On: The access point allows the LANCOM WLC to handle the client steering.



2.3) The menu Configuration -> WLAN controller -> AP configuration -> Extended settings -> Client steering profiles... contains 2 pre-configured default profiles (high density & default), which are suitable for most applications. This example uses the high density profile.


    If you wish to create a customized client steering profile, click the Add button. In the dialog box that opens, perform the following settings:


    • Name: Name of the client steering profile.
    • Pref. Frequency band: Specifies the frequency band to which the LANCOM WLAN controller preferentially steers the WLAN client.
      • 2.4GHz: The WLC steers the WLAN client to the 2.4-GHz frequency band.
      • 5GHz: The WLC steers the WLAN client to the 5-GHz frequency band.
    • Tolerance level: The percentage by which the calculated value for an access point deviates from the maximum calculated value in order for the access point to accept the WLAN client at the next login attempt.
    • Signal weighting: Specifies the percentage weighting of the signal-strength value used to calculate the final value.
    • Client count weighting: Specifies the percentage weighting of the number of clients associated with an access point for calculating the final value.
    • Frequency weighting: Specifies the percent weighting of the value for the frequency band used to calculate the final value.
    • Disassociation threshold: The disassociation threshold is a percentage of the maximum signal strength. If the current signal strength falls below this value, the WLAN client is disconnected.
    • Disassociation delay: Specifies the number of seconds in which no data is transferred between access point and client before the access point disconnects the WLAN client.
2.4) Navigate to the menu Configuration -> WLAN controller -> AP configuration -> Access point table and assign a client steering profile to an existing entry.

    Information:
    If your existing installation is operating with the default profile, merely assigning a client-steering profile to the default profile is not sufficient. In this case, the client-steering profile needs to be manually assigned to the known access points in the list.



2.5) Close the dialogs with the OK button and write the configuration back to the WLAN controller. This concludes the configuration.


3) Function check:

After carrying out the configuration, you can check the functionality of the client-steering feature by associating several WLAN clients (optimally with 2.4GHz and 5GHz devices) with an SSID.

The LANCOM WLC analyzes the data from the associated WLAN clients and distributes them between the access points according to the relevant client-steering profile. You can view this information by opening the LANCOM WLC in LANmonitor.



If you have enabled the option Acquire statistical data under Configuration -> WLAN controller -> AP configuration, you can also view the statistics in LANmonitor.

    Information:
    Statistics capture increases the load on the WLC. We do not recommend the permanent recording of statistics. By default the option Acquire statistical data is enabled.