Problems running ath with bgscan enabled

[Sam Leffler]

AT Matik wrote:
> On Saturday 20 October 2007 22:30:32 Kevin Oberman wrote:
>   
>> 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?
>>
>>     
>
> I believe it is so but as you already did, when you like to associate only to 
> the AP of your wpa config you should set -bgscan and eventually 'roaming 
> manual' also, if I am not wrong this is described in ifconfig's manpage
>
>   

wpa_supplicant works fine w/ bgscan.  When the bgscan's complete 
wpa_supplicant receives an event and retrieves the scan results.  It 
then decides whether or not to roam.  There is no need to manually 
configure the device.

OTOH the scanning+roaming code in wpa_supplicant is very simplistic and 
I don't have a lot of experience with how well it does roaming.  I 
believe it will only join ap's that are listed in the config file so it 
shouldn't roam arbitrarily.  Without a log it's virtually impossible to 
comment on reports/complaints.  And even w/ a wpa_supplicant log it's 
also useful to understand if there are other events that trigger 
scanning and/or roaming--like beacon miss events.  Hence the need for 
logs and statistics.

    Sam