Subject: Re: SIOCSIWESSID + SIOCSIWAP behaviour

From: Jouni Malinen <[email-masked]>
Date: Mon, 15 May 2006 14:40:14 -0700

On Mon, May 15, 2006 at 01:28:13PM -0700, Jean Tourrilhes wrote:

> 	I believe the BSSID has to be unique. HP APs can also offer
> multiple ESSID for the same BSSID, but they do so using different
> BSSID. If you look at the 802.11 spec, I can't see how two different
> virtual cells can have the same BSSID, because the BSSID is the only
> thing that identify the cell (the ESSID is not in each packet).

What the standard says is somewhat irrelevant since there are APs that
use multiple SSID with the same BSSID. I would say that it is reasonable
for users to expect that this works with Linux, too.

> 	Personally, I think that SIWAP is too tricky to use properly
> for most users, so we should encourage them to not use it.

Keep in mind that it is also used by some programs (e.g., wpa_supplicant
in ap_scan=1) without the user having to know anything about that level
of details..

> 	There is still a performance issue. Having to cancel and
> restart associations waste CPU cycles. One way to deal with that would
> be to improve the "commit" strategy of the Wireless API. Basically,
> every time you do a set, you schedule or reschedule the "commit" ioctl
> to happen in a few dozen ms. This way, you could bundle all the
> settting of apps such as wpa_supplicant with only a single
> commit. This is similar to the way the routing API works.

Number of drivers use an atomic "associate" command (usually, a private
ioctl) with wpa_supplicant. If there were a standard way of doing that,
it could be helpful.

-- 
Jouni Malinen                                            PGP id EFC895FA