Roaming behavior

Roaming behavior

[David Seira]

Hi.

I asked in the ath5k-user list about how to change roaming behavior of
ath5k. Pavel Roskin told me that I asked here.
I need to modify the roaming behavior, where can I do this?

Thanks for all,
David

P.D: sorry for my poor english

Re: Roaming behavior

[John W. Linville]

On Tue, Aug 11, 2009 at 12:44:51PM +0000, David Seira wrote:

> I asked in the ath5k-user list about how to change roaming behavior of
> ath5k. Pavel Roskin told me that I asked here.
> I need to modify the roaming behavior, where can I do this?

This is mostly in the hands of wpa_supplicant...what modifications
do you want to make?

John
-- 
John W. Linville		Someday the world will need a hero, and you
linville@tuxdriver.com			might be all we have.  Be ready.

Re: Roaming behavior

[David Seira]

El mar, 11-08-2009 a las 09:59 -0400, John W. Linville escribió:
> On Tue, Aug 11, 2009 at 12:44:51PM +0000, David Seira wrote:
> 
> > I asked in the ath5k-user list about how to change roaming behavior of
> > ath5k. Pavel Roskin told me that I asked here.
> > I need to modify the roaming behavior, where can I do this?
> 
> This is mostly in the hands of wpa_supplicant...what modifications
> do you want to make?
> 
> John

Hi.
I want to delete this behavior because I'm developing an application
which do that alone.

Thanks for all,
David

P.D: I have an OpenWRT r16278. The files that I want to modify were in
compat-wireless-2009-05-21, but I don't know which are.

Re: Roaming behavior

[Holger Schurig]

> I want to delete this behavior because I'm developing an
> application which do that alone.

Please look at wpa_supplicants behavior when you configure 
ap_scan= and scan_ssid=. With them, you can configure 
wpa_supplicant to not issue scan requests on it's own.

Then your user-space app can do the monitoring, scanning (via 
nl80211) issue a command to wpa_supplicant to authenticate to 
some AP.

Another option would be to look into network-manager and see what 
it offers.


But basically, mac80211 has inferior support for roaming compared 
to some older solutions.

Some examples: with madwifi, I can tell the driver to only scan 
on channels 1,6,11. That's not exactly standards-conforming, but 
can speed up roaming considerably, because a full scan is now 
way shorter. mac80211 doesn't support such a thing directly. It 
just occurs to me that you might be able to do something like 
with with a special regulatory daemon.

Or with orinoco, you could define a level when to roam (e.g. at 
what SNR/RSSI/whatever it is based on). mac80211 doesn't have 
this.



I'm quite sure that this will be eventually done, and then you 
have the same seamless roaming with all/most of your WLAN cards, 
where with the pre-mac80211 only some of the card did somewhat 
well and other cards were only usable for hot-spot operation.

-- 
http://www.holgerschurig.de

Re: Roaming behavior

[Johannes Berg]

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On Wed, 2009-08-12 at 09:07 +0200, Holger Schurig wrote:

> Some examples: with madwifi, I can tell the driver to only scan 
> on channels 1,6,11. That's not exactly standards-conforming, but 
> can speed up roaming considerably, because a full scan is now 
> way shorter. mac80211 doesn't support such a thing directly. It 
> just occurs to me that you might be able to do something like 
> with with a special regulatory daemon.

Or you can just ask wpa_supplicant to do that with -Dnl80211.

> Or with orinoco, you could define a level when to roam (e.g. at 
> what SNR/RSSI/whatever it is based on). mac80211 doesn't have 
> this.

The intention is to add signal strength triggers to mac80211/drivers to
notify wpa_supplicant which then implements the algorithm. There are a
ton of algorithms to choose from, so this will be very good for
experimentation, academia and getting the best algorithm eventually :)
Right now you don't have signal strength triggers so you'd have to
monitor the signal strength (like "iw wlan0 link").

johannes

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Re: Roaming behavior

[David Seira]

But I haven't installed wpa_supplicant, I don't need it. In which files is
roaming behavior implemented?

Regards,
David

Re: Roaming behavior

[Dan Williams]

On Thu, 2009-08-13 at 09:44 +0000, David Seira wrote:
> 
> 
> But I haven't installed wpa_supplicant, I don't need it. In which files is
> roaming behavior implemented?

wpa_supplicant is the defacto wifi control program for Linux.  Yes, it
doesn't more than WPA.  Yes, it can be used for open and WEP networks.
If you don't use it, you'll just end up rewriting a large chunk of it.

Dan