Beacon interval for Mesh/AP in single interface

Beacon interval for Mesh/AP in single interface

[Chun-Yeow Yeoh]

Hi, Johannes

The introduction of the following patches doesn't allow the AP and
mesh mode to simultaneously run on a single radio interface due to
beacon interval for both interfaces by default is different.
[PATCH] cfg80211: disallow beacon_int_min_gcd with IBSS
[PATCH] cfg80211: support virtual interfaces with different beacon intervals
[PATCH] cfg80211: validate beacon int as part of iface combinations

Any suggestion that we could solve this.

Thanks

---
Chun-Yeow

Re: Beacon interval for Mesh/AP in single interface

[Johannes Berg]

Hi,

> The introduction of the following patches doesn't allow the AP and
> mesh mode to simultaneously run on a single radio interface due to
> beacon interval for both interfaces by default is different.
> [PATCH] cfg80211: disallow beacon_int_min_gcd with IBSS
> [PATCH] cfg80211: support virtual interfaces with different beacon
> intervals
> [PATCH] cfg80211: validate beacon int as part of iface combinations
> 
> Any suggestion that we could solve this.

Interesting. Did hardware actually support this, and if so, what did it
do?

If that worked, then it'd be reasonable to add the appropriate value to
the interface combinations to let it work as before.

If it didn't really work properly, then we can just fix the defaults to
be compatible?

johannes

Re: Beacon interval for Mesh/AP in single interface

[Chun-Yeow Yeoh]

>
> Interesting. Did hardware actually support this, and if so, what did it
> do?

Yes, ath9k for mesh/AP running simultaneously in one single radio
interface can do beaconing using different beacon interval. Mesh
providing backhaul to user accessing via STA/AP mode.

> If that worked, then it'd be reasonable to add the appropriate value to
> the interface combinations to let it work as before.
>
> If it didn't really work properly, then we can just fix the defaults to
> be compatible?

I try to put beacon_int_min_gcd in the interface combination with
mesh/AP/adhoc but the patch "[PATCH] cfg80211: disallow
beacon_int_min_gcd with IBSS" disables the mesh interface due to adhoc
interface is there.

---
Chun-Yeow

Re: Beacon interval for Mesh/AP in single interface

[Johannes Berg]

On Wed, 2017-03-15 at 16:25 +0800, Chun-Yeow Yeoh wrote:

> Yes, ath9k for mesh/AP running simultaneously in one single radio
> interface can do beaconing using different beacon interval. Mesh
> providing backhaul to user accessing via STA/AP mode.

Ok.

> > If that worked, then it'd be reasonable to add the appropriate
> > value to
> > the interface combinations to let it work as before.
> > 
> > If it didn't really work properly, then we can just fix the
> > defaults to
> > be compatible?
> 
> I try to put beacon_int_min_gcd in the interface combination with
> mesh/AP/adhoc but the patch "[PATCH] cfg80211: disallow
> beacon_int_min_gcd with IBSS" disables the mesh interface due to
> adhoc interface is there.

Can we split the combination? Or should we just work on fixing this
limitation? Perhaps we could say that if beacon_int_min_gcd is 1, then
that obviously means that there's no real restriction, and then we can
allow with IBSS? How would the hardware react if you had one interface
with beacon interval 99 TU and another with 100 TU? they can collide,
but if there's some kind of mitigation it wouldn't matter, just one of
them would come late after the TBTT...

If it seems reasonable for this hardware to advertise
beacon_int_min_gcd==1, then I think we can change cfg80211 to allow
IBSS in that case.

johannes