APs and multiple BSSID support (OT?)

Jouni Malinen jkmaline at cc.hut.fi
Tue Feb 6 23:01:27 EST 2007

On Tue, Feb 06, 2007 at 10:06:41AM -0700, Bob Carlson wrote:
> Perhaps this is a little OT, but this seems like a good community to which
> to address this question. I'm using wpa_s in a Wifi client device that acts
> like multiple virtual clients. One key problem is APs that support multiple
> SSIDs. Atheros calls these virtual APs. Cisco doesn't call them anything,
> they just refer to "multiple SSIDs". Unlike the Atheros code that I am
> familiar with, Cisco allows multiple SSIDs on a single BSSID, but you can
> enable multiple BSSIDs.

Could you please describe the problem in bit more detail than it just
existing.. Rest of your email seems to be about the AP side, but if I
understood correctly, the problem you are describing is for the virtual
client device.

> In the Atheros case, when more than one BSSID is needed, they generate it
> using the private mac address space.

> Cisco uses a more straightforward approach, just adding 1 to byte 5.

> Does anyone know of any other different methods of generating multiple

Yes.. Depending on the hw design, one could use any of the BSSID bits
(apart from local and broadcast) to generate new addresses. Local
address space makes it easier to get large number of addresses, but if
one happens to have a large space of addresses available, it would be
possible to allocate set of addresses for each device (though, IEEE
might get somewhat unwilling to allocate more OUIs for this kind of
address use if large portion of the addresses are not really used).

Different designs might support list of arbitrary addresses or some sort
of bitmask on the addresses, so at least in theory, the sets of
addresses could be quite diverse.

Jouni Malinen                                            PGP id EFC895FA

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