wpa_supplicant keeps de- and reassociating

[Mel]

On Wednesday 27 February 2008 23:11:24 Kevin Oberman wrote:
> > Date: Wed, 27 Feb 2008 11:36:48 +0100
> > From: Tobias Roth <freebsd.lists at fsck.ch>
> > Sender: owner-freebsd-mobile at freebsd.org
> >
> > Hi
> >
> > I see the following when I connect to the universitys wlan with
> > 7.0-PRERELEASE and if_ath0:
> >
> > I associate to a wlan using wpa_supplicant. There are several base
> > stations for the same network around. First-time association works a bit
> > slow but otherwise well, but then, after a while (quite frequently),
> > something initiates a rescan, and the connections drops for some time.
> > The laptops position was not changed during that time.
> >
> > Then, most of the time, things fix themselves and the interface
> > reassociates, but this can take sme time. If I issue "ifconfig ath0" a
> > few times during one of those dropouts, I can see different channels
> > being tried, and also sometimes my ssid is shown, sometimes no ssid is
> > shown during scanning.
> >
> > Questions:
> >
> > 1) what is causing these deassociate/scan/reassociate cycles?
>
> Background scans are causing it. They should not, but I have seen it a
> lot. I only see it when I travel and am in a location where there are
> multiple APs.
>
> > 2) why is it unsetting the ssid, when I explicitly set it in wpa_conf?
>
> I assume you mean wpa_supplicant.conf, but I don't know why. I know that
> I see it on my Atheros 5212. I have some guesses, but I have been
> unable to confirm anything.
>
> I suspect that it is if the BG scan completes and did not see the
> current AP, even if the current AP is active. It may also be that a
> different AP is stronger when the scan takes place.
>
> I can only troubleshoot this on occasion when I am someplace where I
> get several APs...usually at a conference, so I may not get a chance to
> collect information any time soon.
>
> > 2) how can I stop this (i.e. keep the current connection after initial
> > association?
>
> ifconfig ath0 -bgscan (as superuser) after the initial association has
> completed successfully. (I could probably do it by putting "-bgscan" im
> the ifconfig_ath0 line in my rc.conf.local. This would have a negative
> impact on roaming, though, so it is not the ideal solution, just one
> that works fairly well.
>
> Something is simply interacting badly between the wpa_supplicant and the
> background scans, but tracking it down will be a real pain!

I'm not sure that it's wpa_supplicant alone, but I did see it more on the 
wpa_supplicant machine. We switched it over to wire now, cause it was 
interrupting too much being the main nfs server, but it wouldn't be too hard 
to switch it back on, even as secondary nic, just to see it re-associating.

-- 
Mel