WPA Supplicant causes timeouts

Dan Williams dcbw at redhat.com
Mon Nov 7 09:10:42 PST 2016

On Sat, 2016-11-05 at 18:28 +0100, Nickolai Dobrynin wrote:
> Weedy,
> I *am* using NetworkManager.  Sorry, I should've
> pointed that out.  Do you suggest NM's causing
> timeouts?
> The reason I was suspecting WPA Supplicant was
> that the problem started after a WPA Sup upgrade
> last February, as I explained in the original message.

If I'm reading the original mail correctly, you're seeing frequent re-
association bounces between 2 and 5 ghz BSSIDs.  This is caused by two

1) NetworkManager requesting periodic scans to help ensure smooth
roaming between APs of the same SSID.  If you don't need this, eg if
you're not running multiple access points connected to each other in
the same network, or you don't care about seamless roaming between
them, then you can lock your NetworkManager wifi connection to a single
BSSID and NM won't scan periodically.

2) becuase of the NM scan request, when the supplicant gets its results
it looks for a better AP.  And it finds one; the 2.4GHz AP's signal is
significantly better than the 5GHz one, so the supplicant jumps over to
the 2.4GHz AP instead.  The supplicant has been pretty twitchy about
this for a long time, to the point that we've patched this in
Fedora/RHEL to use slightly larger difference values.  Also the
supplicant is apparently not considering throughput in your case, only
signal strength.

That said, the roam takes less than a second.  Are these two APs (the
2.4 and the 5ghz) connected to the same physical network and using the
same SSID?  If so, there shouldn't be any timeouts becuase it should be
an in-ESS roam.  If they aren't, it's an out-of-ESS roam and NM would
then have to re-DHCP which could cause lost packets.

But in the end, it's probably any NM bug that NM isn't telling the
supplicant not to roam as a result of periodic scans.


> Many thx.
> On Sat, Nov 5, 2016 at 7:50 AM, Weedy <weedy2887 at gmail.com> wrote:
> > 
> > On Fri, Nov 4, 2016 at 5:57 PM, Nickolai Dobrynin <ndobrynin at gmail.
> > com> wrote:
> > > 
> > > Hey guys,
> > > 
> > > Can someone please get back to me (see below)?
> > > This is really disruptive to have timeouts, after
> > > timeouts, after timeouts.  I would like to know if my
> > > question is trivial.  Or perhaps it's being looked into,
> > > but no resolution had been found.
> > 
> > 
> > Do you use NetworkManager?
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