How to disable /b and /a/g rates?

Ben Greear greearb
Tue Mar 10 13:19:33 PDT 2015

On 03/10/2015 01:05 PM, Johannes Berg wrote:
> On Tue, 2015-03-10 at 12:52 -0700, Ben Greear wrote:
>> On 03/10/2015 12:44 PM, Johannes Berg wrote:
>>> On Tue, 2015-03-10 at 12:27 -0700, Ben Greear wrote:
>>>> Regardless of how good of an idea this is for real-world deployment,
>>>> would it actually be OK per the wifi spec to disable all basic rates?
>>> You seem to be confusing a few things. You cannot "disable all basic
>>> rates", as the AP determines which rates are basic rates. Certainly, if
>>> the AP doesn't advertise a rate, then it can also not be marked as a
>>> basic rate.
>> I guess I mean that I would want only the HT rates to be the
>> basic rates..none of the /b/g/a rates...
> Oh, so you want to basically support the legacy rates, but not mark them
> as basic rates? That might even work. But then you'd still not 'pure
> HT'.
> Btw, HT had something called "greenfield" though I think VHT ignored
> that.

I think I don't know enough about basic rates and supported rates,
and I am probably using the terms all wrong.

What I mean is that I was hoping that I could get the AP to use
HT rates as it's very slowest rate (ie, beacon at HT-MCS0 or something
like that).

>> Also, in this case, I am interested in doing this on the AP.
>> I basically want to have an /n/AC AP legacy stuff
>> at all.
> That's different from just not having those rates as basic rates though,
> that means you're saying you don't want to support those rates at all,
> which I believe to not be compliant.

Ok.  You think it would also be non-compliant to just disable
the /b rates on 2.4Ghz (and leave the /g rates as supported)?

>> For grins, I tried setting the supported_rates=360 480 540
>> In this case, it seems hostapd at least thinks it has started,
>> but ath10k will not beacon as far as I can tell.
>> That could easily be bugs in ath10k driver or firmware...I'll
>> go poke around there next.
> Not really surprising, usually you *want* the beacons at a lower rate to
> have other devices around find them. This, btw, includes legacy devices
> even if they're not allowed to connect to you - they still have to
> interoperate with you on the same channel.

/b (and all other devices) must already interoperate with non wifi
devices such as baby monitors and such, right?

So, wouldn't that sort of work the same as an AP that was beaconing
with a modulation that the device couldn't understand?

For that matter, the /b device is already not going to understand
the vast majority of the traffic even if the beacons them selves
are running at minimal rates?


> johannes

Ben Greear <greearb at>
Candela Technologies Inc

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