Client steering by WLC

With client steering, certain criteria are used to help WLAN clients located within transmission range to connect to the best suited AP. These criteria are centrally defined in the WLC. Managed APs constantly report the current values to the WLC, which uses these criteria to decide which APs may respond to requests from WLAN clients. For this reason, client steering is only possible with APs that are centrally managed by a WLC.

In managed networks a WLC centralizes the client steering for all connected APs. In this case, client steering works as follows:

The 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.
All APs are configured so that client steering is handled by the WLC.
An unassociated WLAN client sends a probe request to the APs within its range.
Using CAPWAP, the APs transmit the request and the signal strength of the WLAN client to the WLC.
For each AP within range of the WLAN client, the WLC calculates a value from three factors:
- Signal strength value
- A value calculated from the number of clients associated at the AP
- Frequency band value
The WLC weights these factors and multiplies them together to derive the final value.
APs with the highest value, or a value that deviates from it within a specified tolerance level, receive a message from the WLC that they may accept the WLAN client at the next login attempt.
WLAN clients attempting to connect to an AP before it has received the response from the WLC are rejected.
If a WLAN client is acting "sticky", i.e. it does not attempt to connect to another AP with a good connection quality even though its current connection is of a lower quality, the WLC can prompt the current AP to log off the WLAN client. The WLAN client is then forced to connect with the AP offering the better connection.

Note: If an AP loses connection to the WLC which is responsible for client steering, the AP accepts all connections from authenticated WLAN clients.

Important: In order to optimize managed client steering, all APs require the installation of LCOS9.00 or later. If you have mixed operations with APs using earlier versions of LCOS, your WLAN will not be capable of optimizing the distribution of clients.

Important: In scenarios with time-critical roaming, such as with VoIP phones, you should not use client steering, as this can delay the client's login process.