User's Manual

445 | Adaptive Radio Management (ARM) Dell Networking W-Series ArubaOS 6.4.x| User Guide
If the AP Monitor detects that a channel on the 802.11g band does not have adequate radio coverage, it will
convert back to an AP on that 802.11 channel. If the 802.11g band is adequately covered, the AP Monitor will
next check the 802.11a band. If a channel on the 802.11a band lacks coverage, the AP Monitor will convert
back to an AP on that 802.11a channel.
Band Steering
ARM’s band steering feature encourages dual-band capable clients to stay on the 5GHz band on dual-band APs,
freeing up resources on the 2.4GHz band for single-band clients like VoIP phones.Band steering reduces co-
channel interference and increases available bandwidth for dual-band clients, because there are more channels
on the 5GHz band than on the 2.4GHz band. Dual-band 802.11n-capable clients may see even greater
bandwidth improvements, because the band steering feature will automatically select between 40MHz or
20MHz channels in 802.11n networks. This feature is disabled by default, and must be enabled in a Virtual AP
profile.
The band steering feature considers several metrics before it determines if a client should be steered to the
5GHz band, including client RSSI. For example, this feature will only steer a client to the 5GHz band if that client
detects an acceptable RSSI value from an 5GHz AP radio, and the signal from the 5Ghz radio is not significantly
weaker than the RSSI from the 2.4GHz radio.
This feature also takes into account the current load on each radio of a dual-band AP. The band steering
feature will not steer more clients to 5G on that AP if there are many clients associated to the AP, and
significantly more 802.11a clients than 80211g clients.b
The band steering feature supports both campus APs and remote APs that have a virtual AP profile set to
tunnel, split-tunnel, or bridge forwarding mode. Note, however, that if a campus or remote AP has virtual AP
profiles configured in bridge or split-tunnel forwarding mode but no virtual AP in tunnel mode, those APs will
gather information about 5G-capable clients independently and will not exchange this information with other
APs that also have bridge or split-tunnel virtual APs only. The band steering feature will not proactively
disconnect clients that are already associated with a radio. All band steering occurs when a client is trying to
associate to a new AP radio.
Best practices are to use either the Band Steering or the Client Match feature to balance client loads, but not both at
the same time.
Steering Modes
Band steering supports the following three different band steering modes:
l Prefer-5GHz (Default): If you configure the AP to use prefer-5GHz band steering mode, the AP will not
respond to 2.4 Ghz probe requests from a client if all the following conditions are met.
n The client has already probed the AP on the 5Ghz band and therefore is known to be capable of sending
probes on the 5Ghz band.
n The client is not currently associated on the 2.4Ghz radio to this AP.
n The client has sent fewer than 8 probes in the last 10 seconds. If the client has sent more than 8 probes
in the last 10 seconds, the client will be able to connect using whatever band it prefers
l Force-5GHz: When the AP is configured in force-5GHz band steering mode, the AP will not respond to 2.4
Ghz probe requests from a client if all the following conditions are met.
n The client has already probed the AP on the 5Ghz band and therefore is known to be capable of sending
probes on the 5Ghz band.
n The client is not currently associated on the 2.4Ghz radio of this AP.
l Balance-bands: In this band steering mode, the AP uses client load and RSSI information balance the
clients across the two radios and best use the available 2.4G bandwidth. This feature takes into account the