wpa_supplicant and IAPP

Jouni Malinen j at w1.fi
Sun May 23 07:00:40 EDT 2010


On Fri, May 14, 2010 at 05:02:10PM +0200, Benoit Dolives wrote:

> I would like that my Mobile Host switch quickly from an AP to another 
> (less than 1sec).
> When I want to switch from one to another AP I use :
> 
> "wpa_cli bssid my_network wanted_bssid
> wpa_cli reassociate"
> 
> but then it needs between 2 and 5 seconds to connect. Therefore I am not 
> sure it is the good way to do it.

Have you profiled which operations take most of that time? I would
assume that large part of it comes from scanning..

> I am looking for doing a pre-registration to the new AP then a quick 
> handoff.

IEEE 802.11r could help there, but it is not needed for meeting
something like "less than 1 second" (much more so on less than 50
millisecond). In addition, wpa_supplicant will try to use RSN
pre-authentication if the APs support it and same for proactive key
caching with your configuration.

I would suggest running wpa_supplicant with -ddt on command line and
then going through the timestamps to figure out which part is taking
most time.

If you know on which channels the APs are, you can also add scan_freq
configuration parameter with the current development version of
wpa_supplicant. With -Dnl80211 (instead of -Dwext), this would likely
speed up the connection quite a bit.

-- 
Jouni Malinen                                            PGP id EFC895FA


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