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Subject: Re: iwlwifi: 8265: unexpected LLC packets TX'ed in monitor mode
From:   "Marco" <marco@tampabay.rr.com>
To:     "Johannes Berg" <johannes@sipsolutions.net>,
        <linux-wireless@vger.kernel.org>
Date:   Thu, 28 May 2020 10:26:04 -0400
Message-Id: <C32FKI01HMGA.U0TCA9AIO8BX@b1>
In-Reply-To: <ca2b26a87d49284a07b24c71046993814c4fe821.camel@sipsolutions.net>
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On Mon May 25, 2020 at 7:23 AM EDT, Johannes Berg wrote:
> On Wed, 2020-05-13 at 13:48 -0400, Marco Fonseca wrote:
> > Hello,
> >=20
> > While in monitor mode, the 8265 will periodically transmit gratuitous
> > LLC packets.  In this mode, I would expect the wifi chipset to not
> > transmit any packets at all (unless packet injection is being used).
> >=20
> > This behavior can be observed by a second wifi device in monitor mode.
> > A display filter on wireshark/tshark of 'llc' makes these easy to spot.
> >=20
> > It seems these packets only get produced in presence of a few APs
> > and/or STAs but I'm not sure of the exact cause.  I don't see the LLC
> > packets on very quiet channels.
>
> I think these are somehow related to calibrations in the device.
>
> johannes

Are you perhaps implying that I can alter calibration settings to fix
this problem?  If you have any pointers to this it would be
appreciative.

Regardless though, I would still expect the default behavior to not
emit packets when in monitor mode, unless the user directs it to;
similar to what I've seen from other wifi chipsets.

Marco