* active vs. passive scans
@ 2010-09-27 14:03 Chuck Crisler
2010-09-27 15:06 ` Luciano Coelho
0 siblings, 1 reply; 4+ messages in thread
From: Chuck Crisler @ 2010-09-27 14:03 UTC (permalink / raw)
To: linux-wireless
How to you get the supplicant/linux wireless to perform active scans rather
than passive scans? Are active scans faster?
Thank you,
Chuck
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: active vs. passive scans
2010-09-27 14:03 active vs. passive scans Chuck Crisler
@ 2010-09-27 15:06 ` Luciano Coelho
2010-09-27 15:09 ` Johannes Berg
0 siblings, 1 reply; 4+ messages in thread
From: Luciano Coelho @ 2010-09-27 15:06 UTC (permalink / raw)
To: ext Chuck Crisler; +Cc: linux-wireless@vger.kernel.org
Hi Chuck,
On Mon, 2010-09-27 at 16:03 +0200, ext Chuck Crisler wrote:
> How to you get the supplicant/linux wireless to perform active scans rather
> than passive scans? Are active scans faster?
We do active scans by default, unless specified otherwise in the
regulatory database.
The main difference between active and passive scans is that in active
scans we send broadcast probe requests on the channel and with passive
we don't. In passive scan we just listen to beacons.
Usually the drivers stay for a certain period of time in each channel,
and that normally doesn't change if you have active or passive scan. So
there will be no improvement in the overall scan speed. Of course you
could do some tweaks that might improve scanning performance in specific
cases.
--
Cheers,
Luca.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: active vs. passive scans
2010-09-27 15:06 ` Luciano Coelho
@ 2010-09-27 15:09 ` Johannes Berg
2010-09-27 16:32 ` Luciano Coelho
0 siblings, 1 reply; 4+ messages in thread
From: Johannes Berg @ 2010-09-27 15:09 UTC (permalink / raw)
To: Luciano Coelho; +Cc: ext Chuck Crisler, linux-wireless@vger.kernel.org
On Mon, 2010-09-27 at 18:06 +0300, Luciano Coelho wrote:
> Usually the drivers stay for a certain period of time in each channel,
> and that normally doesn't change if you have active or passive scan. So
> there will be no improvement in the overall scan speed. Of course you
> could do some tweaks that might improve scanning performance in specific
> cases.
It's certainly different with mac80211:
#define IEEE80211_CHANNEL_TIME (HZ / 33)
#define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
johannes
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: active vs. passive scans
2010-09-27 15:09 ` Johannes Berg
@ 2010-09-27 16:32 ` Luciano Coelho
0 siblings, 0 replies; 4+ messages in thread
From: Luciano Coelho @ 2010-09-27 16:32 UTC (permalink / raw)
To: ext Johannes Berg; +Cc: ext Chuck Crisler, linux-wireless@vger.kernel.org
On Mon, 2010-09-27 at 17:09 +0200, ext Johannes Berg wrote:
> On Mon, 2010-09-27 at 18:06 +0300, Luciano Coelho wrote:
>
> > Usually the drivers stay for a certain period of time in each channel,
> > and that normally doesn't change if you have active or passive scan. So
> > there will be no improvement in the overall scan speed. Of course you
> > could do some tweaks that might improve scanning performance in specific
> > cases.
>
> It's certainly different with mac80211:
>
> #define IEEE80211_CHANNEL_TIME (HZ / 33)
> #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
Right... Even in the wl1271 driver's hw scan we stay longer on each
channel for passive scans. Obviously just listening to beacons we need
to wait more, because probe_reqs should be responded quickly.
--
Cheers,
Luca.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2010-09-27 16:33 UTC | newest]
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2010-09-27 14:03 active vs. passive scans Chuck Crisler
2010-09-27 15:06 ` Luciano Coelho
2010-09-27 15:09 ` Johannes Berg
2010-09-27 16:32 ` Luciano Coelho
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