wpa_supplicant keeps de- and reassociating

[Kevin Oberman]

> 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!

Still using profile.sh!
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634
Key fingerprint:059B 2DDF 031C 9BA3 14A4  EADA 927D EBB3 987B 3751
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