wpa_supplicant roaming question

[Matt Causey]

Hello,

I have a question about how scans are meant to be triggered with
wpa_supplicant, mac80211, and family.  At my site, we have a fleet of
small devices that run the Atheros ar928x wireless cards.  We use
EAP-TLS on Motorolla WLAN infrastructure.  We're running linux
2.6.38-2 with no vendor patches.  Our wpa_supplicant version is 0.7.3.

In our situation, we'll have a client adjacent to 2 or 3 BSSIDs
broadcasting the same ESSID, and the client moves about from time to
time.  What I am seeing is that the client will sit on a -70 access
point, without roaming, for hours even in the presence of another
access point that registers as -50.  However, if I do something to
manually trigger a scan, the device will suddenly roam to the more
favorable access point.

For example, I can do 'iwlist scan', or HUP the supplicant.  iwlist I
am sure causes the driver to generate a new set of scan results -
which the supplicant picks up and uses.  HUP of the supplicant causes
the supplicant to call wpa_supplicant_req_scan(), and then roam as a
result of the new scan data.  This leaves me thinking that the roaming
algorithm is working great, it's just that the background scanning is
not working as I would expect...

So I read about bgscan here:
http://hostap.epitest.fi/gitweb/gitweb.cgi?p=hostap-07.git;a=commit;h=e2f74005f548d90014cdf080802d455382e37cb9

It looks like what I want - to configure the supplicant to scan
periodically.  However I have it enabled and I don't ever see it kick
in.  Any ideas why?

Here is our supplicant config:

network={
	ssid="wpa2"
	bgscan="simple:30:-45:300"
	freq_list=<a list of the frequencies that we use>
	identity="<client-id>"
	key_mgmt=WPA-EAP
	proto=WPA2
	pairwise=CCMP
	group=CCMP
	eap=TLS
	ca_cert="/etc/cert/root.pem"
	client_cert="/etc/cert/user_cert.pem"
	private_key="/etc/cert/user_key.pem"
	private_key_passwd="<noober mic nooberson>"
}

If there is other info I can provide please let me know!

Cheers,

--
Matt