Hello,
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).
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.
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.
Other Details
-------------
wifi chipset:
Intel(R) Dual Band Wireless AC 8265, REV=0x230
kernel:
4.9.11 kernel
backports driver:
iwlwifi-stack-public:release/core33:6653:327571a8
I can use other backports versions if needed, but this was the
version called out in:
https://wireless.wiki.kernel.org/en/users/drivers/iwlwifi/core_release
Firmware:
36.952d9faa.0
Thank you,
Marco Fonseca
On Wed, 2020-05-13 at 13:48 -0400, Marco Fonseca wrote:
> Hello,
>
> 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).
>
> 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.
>
> 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
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,
> >
> > 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).
> >
> > 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.
> >
> > 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
On Thu, 2020-05-28 at 10:26 -0400, Marco wrote:
>
> > I think these are somehow related to calibrations in the device.
>
> 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.
No, I don't know if this is possible. I'm just telling you what I think
the reason for them is.
> 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.
I have no idea precisely why (for what kind of calibration) these are
transmitted and if it could be changed, I guess you could try contacting
Intel's customer support?
johannes