Band Steering - How to Configure?

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How to configure band steering
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Mike O'Nan

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Posted 3 years ago

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Mike O'Nan

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Not sure what happened to my full description. I have been searching Google for how to configure band steering. I have a single demo AP and have found answers leading to the radio profile. When looking there I don't see much about it? 
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Mike Kouri, Official Rep

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Hello Mike,
Take a look at the online help for Radio Profiles, specifically the section titled "Optimizing Management Traffic Settings"; that should get you started.
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Roberto Casula, Champ

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Be aware that band steering can sometimes cause more problems than it solves. Sometimes it can be effective, but often you will find it doesn't actually make any tangible difference to how your clients connect and in the worst case might actually cause problems with client connectivity and roaming. You should be especially careful if you are using your wireless network for real time applications (voice/video) as the impact on roaming can cause quality issues.

Band steering effectively works by the AP selectively responding to probe requests from clients and by actively refusing association requests from clients on one radio in the "hope" that they will instead try to associate to the other radio. Whether or not this works is very much dependent on how the client software and drivers have been written. It also means that a client may take longer than normal to associate which is what causes the impact on roaming performance.

First of all the AP needs to determine that a given client is capable of operating on both radios. It does this by listening out for probes from the same client on the two radios. The problem is that some clients send probes much more frequently on one radio than on the other (perhaps in an attempt to save power) - Samsung devices are particularly bad for this. This means the AP is not able to determine that a client is 5GHz capable and therefore will not perform band steering from 2.4GHz to 5GHz for that client.

Secondly, and mostly historically - and again mostly with Samsung devices, some clients misinterpret the association refusal by the AP as an AUTHENTICATION failure and instead of retrying association on the other radio, they present the user with an error message or request for credentials/pre-shared key to be re-entered. (Aerohive actually added a default workaround for this bug which actually excludes Samsung devices from band-steering consideration at all, though Samsung have now fixed the issue in later Android software updates).

Thirdly, some clients simply refuse to be bludgeoned into associating with the other radio and insist on continually retrying the association on the original radio. The band-steering configuration will eventually allow such clients to connect, but it can lead to a bad user experience, extra load on the AP and in the worst case the client may give up completely and not connect at all.

Finally, it's worth bearing in mind that many clients either themselves prefer to associate using the 5GHz radio by default (most Apple devices for example) or can be configured to do so (most laptops etc. via driver settings) and this client-side setting is much more reliable and less problematic than band steering.

A lot of the above also applies to load-balancing between APs as a very similar mechanism is used there to "encourage" clients to connect to a different AP than the one they believe has the best signal. 802.11k should help here eventually, but at the moment it's still problematic and has limited client support (and a fair number of bugs in the client-side implementation for devices that DO support it)..

I should make it clear that the above are not an Aerohive limitation. You will find similar results with other vendors that have a band steering function - essentially there are only a few ways that band steering can be accomplished and they all involve effectively "lying" to the client in some way and hoping that the client will behave in a particular way in response to that "lie".