Selection should be enabled.
enables client radios that are capable of dual-band (2.4 and 5 GHz) operation
to move to a less congested 5 GHz AP. 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 APs because of the 802.11b/g limit of three non-overlapping channels. To
prevent these sources of interference and improve overall network performance,
you can configure band selection on controller:
selection is enabled globally by default.
selection works by regulating probe responses to clients. It makes 5 GHz
channels more attractive to clients by delaying probe responses to clients on
2.4 GHz channels.
band selection for voice, particularly focusing on roaming performance. See
below for further explanation.
model clients prefer 5 GHz by default if the 5 GHz signal of the AP is equal to
or stronger than the 2.4-GHz signal.
should be enabled for high-density designs
high-density designs, the study of available UNII-2 channels should be made.
Those channels that are unaffected by Radar and also usable by the client base
should be added to the RRM DCA list as usable channels.
roaming can be slow depending on the client. If a majority of the base of voice
clients exhibits a slow roaming behavior, it is more likely that the client
sticks to 2.4 GHz. In this case, it has scanning issues on 5 GHz. Generally
when a client decides to roam, it scans its current channel and band first. The
clients generally scan for an AP that has a significantly better signal level,
maybe as much as 20 dB and/or a significantly better SNR. Failing such
available connection, the client may remain with its current AP. In this case,
if the CU on 2.4 GHz is low and the call quality is not poor, then disabling
the selected band maybe fine. However, the preferred design is to enable band
selection on 5 GHz with all data rates enabled and 6 Mbps as mandatory. Then,
set the 5 GHz RRM minimum Tx power level 6 dBm higher than the average 2.4 GHz
power level set by RRM.
The goal of
this configuration recommendation is to enable the client to obtain a band and
channel with better SNR and Tx power initially. As already stated, generally
when a client decides to roam, it scans its current channel and band first. So,
if the client initially joins the 5 GHz band, then it is more likely to stay on
the band if there are good power levels on 5 GHz. SNR levels on 5 GHz are
generally better than 2.4 GHz because 2.4 GHz has only three Wi-Fi channels and
is more susceptible to interference such as Bluetooth, iBeacons, and microwave
recommended to be enabled with dual-band reporting. This enables all 11k
enabled clients to have the benefit of assisted roaming. With dual-band
reporting enabled, the client receives a list of the best 2.4-GHz and 5-GHz APs
upon a directed request from the client. Here, the client most likely looks at
the top of the list for an AP on the same channel, and then on the same band as
the client is currently on. This logic reduces scan times and saves battery
power. Having 802.11k enabled on the WLC does not have a downside effect for