Problems running ath with bgscan enabled

[Kevin Oberman]

Ever since the update of the HAL and the new 802.11 code a few months
ago (in current), I have been having problems, especially when I was in
locations with multiple APs available. 

The problem was periodic loss of association. If I was at home where I
can usually only see a couple of APs, the problem would occur an
average of about 10 times a day with re-association in about 10 seconds,
sometimes less. This is annoying, but not very disruptive.

When away from home and in an urban location where there are several
APs, both the frequency of the loss of connectivity and the time to
re-associate increase. Last week at the NANOG meeting there were 4
conference b/g APs and 4 11a APS seen at all times along with the
hotel's tmobile and a couple of random ones. Only the two conference
SSIDs (nanog-arin and nanog-arin-a) were in my wpa_supplicant.conf
file. 

My bgscan interval was the default 300 and almost every 5 minutes I
would lose connectivity, often for over a minute. When I made the
association between the bgscan interval and the drop-outs, I did an
"ifconfig ath0 -bgscan" and things stabilized immediately. No further
problems. 

ath_hal: 0.9.20.3 (AR5210, AR5211, AR5212, RF5111, RF5112, RF2413, RF5413)
ath0: <Atheros 5212> mem 0xb4000000-0xb400ffff irq 11 at device 2.0 on pci11
ath0: mac 5.9 phy 4.3 radio 3.6

This is really not acceptable for default behavior as it won't be clear
to many how to fix it. Is it expected or is something wrong?

Thanks!
-- 
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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