Any idea why we cannot disable /b rates?

Ben Greear greearb at
Wed Feb 25 15:25:37 PST 2015

On 02/25/2015 02:30 AM, Yeoh Chun-Yeow wrote:
> On Wed, Feb 25, 2015 at 1:02 PM, Ben Greear <greearb at> wrote:
>> On 02/24/2015 06:45 PM, Yeoh Chun-Yeow wrote:
>>> On Wed, Feb 25, 2015 at 3:44 AM, Ben Greear <greearb at>
>>> wrote:
>>>> Ok, so I found the problem.  Appears that the firmware uses two different
>>>> fixed rate-ctrl settings, one for non-data (bcast, mgt-frames, etc) and
>>>> another
>>>> for data frames.  The non-data one was not being set when user configured
>>>> fixed rates, so beacons went out at 1Mbps.
>>>> I updated CT firmware (beta-14) to set both data and non-data to the same
>>>> value when the driver specifies the rates...  Seems to work...any idea
>>>> if this is a bad idea in practice?
>>> Rate control is applicable to unicast frame whether it is
>>> management/data. Broadcast/Multicast rate is required for
>>> management/data (usually the lowest transmission rate 5GHz is 6Mbps).
>>> So it is more sensible if we can configure the broadcast/multicast
>>> rate and also disable the rate control for unicast frame by using
>>> fixed rate.
>> User-space API doesn't give the ability to set different fixed rates for
>> different packet types, as far as I know.
>> So, the current firmware just ignores the fixed rate for management and
>> broadcast
>> frames.
>> My firmware change makes the fixed rate apply equally to all types of
>> frames.
>> Should I make my change optional for mgt/bcast , or should it always set
>> mgt/bcast rates to the
>> same fixed rates as data packets use?
> In iw, we have the following:
> dev <devname> set mcast_rate <rate in Mbps>
> dev <devname> set bitrates [legacy-<2.4|5> <legacy rate in Mbps>*]
> [mcs-<2.4|5> <MCS index>*]
> mcast-rate should be something set for broadcast/multicast frame
> including the management and data frame. This allows us to have in
> example beacon frame to be transmitted with higher rate from 1Mbps at
> 2.4GHz and 6Mbps at 5GHz.

Thanks...I'll try to figure out how to work this into my firmware.  But, it will
require driver changes specific to my firmware as far as I can tell,
so it will never make it upstream...


Ben Greear <greearb at>
Candela Technologies Inc

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