Refer the link : https://supportforums.cisco.com/document/81896/load-balancing-and-band-select-cisco-wireless-lan-controller#Band_Select_or_Band_Direction
Band Select or Band Direction
The 2.4-GHz band is often congested. Clients on this band typically experience interference from Bluetooth devices, microwave ovens, and cordless phones as well as co-channel interference from other access points because of the 802.11b/g limit of three non-overlapping channels. You can use this feature to combat these sources of interference and improve overall network performance. Band direction enables client radios that are capable of dual-band (2.4- and 5-GHz) operation to move to a less congested 5-GHz access point.
Band selection works by regulating/suppressing probe responses from the clients? 2.4 GHz radio. It makes 5-GHz channels more attractive to clients by delaying probe responses on the 2.4-GHz channels. The feature is disabled by default. The configurable options are defined globally (Wireless > Advanced > Band Select), but the feature itself can be enabled per WLAN (WLAN > Advanced > Client Band Select). This is useful if you want to disable band selection for a select group of clients (such as time-sensitive voice clients).
Use the following CLI to enable this feature on the WLAN:
(WLC) >config wlan band-select allow enable
The global configuration options are:
(WLC) >config band-select ?
cycle-count Sets the Band Select probe cycle count.
cycle-threshold Sets the time threshold for a new scanning cycle.
expire Sets the entry expire.
client-rssi Sets the client RSSI threshold.
