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:

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.
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.
The client is not currently associated on the 2.4Ghz radio to this AP.
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
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.
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.
The client is not currently associated on the 2.4Ghz radio of this AP.
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 fact that the 5Ghz band has more channels than the 2.4 Ghz band, and that the 5Ghz channels operate in 40MHz while the 2.4Ghz band operates in 20MHz.

Enabling Band Steering

Band steering is configured in a virtual AP profile. Use the following procedures to enable or disable Band Steering using the WebUI or command-line interfaces.

In the WebUI

1. Select Configuration > Advanced Services > All Profiles. The All Profile Management window opens.
2. Select Wireless LAN to expand the Wireless LAN section.
3. Select Virtual AP profile to expand the Virtual AP Profile section.
4. Select the name of the Virtual AP profile for which you want to enable band steering.

(To create a new virtual AP profile, enter a name for a new profile in the Profile Details window, then click Add. The new profile will appear in the Profiles list. Select that profile to open the Profile Details pane.)

5. In the Profile Details pane, select Band Steering to enable this feature, or uncheck the Band Steering checkbox to disable this feature.
6. Once band steering is enabled, click the steering mode drop-down list and select the desired steering mode.
7. Click Apply.

In the CLI

Use the following commands to enable band steering via the command-line interface. Access the CLI in config mode then specify an existing virtual AP with the <name> parameter to modify an existing profile, or enter a new name to create an entirely new virtual AP profile:

(host)(config) #wlan virtual-ap <profile> band-steering

(host)(config) #wlan virtual-ap <profile> steering-mode balance-bands|force-5ghz|prefer-5ghz

To disable band steering, include the no parameter :

(host)(config) #wlan virtual-ap <profile> no band-steering

You can also use the command-line interface to configure and apply multiple instances of virtual AP profiles to an AP group or to an individual AP. Use the following commands to apply a virtual AP profile to an AP group or an individual AP:

(host)(config) #ap-group <name> virtual-ap <profile>

(host)(config) #ap-name <name> virtual-ap <profile>