Re: blacklisting BSSIDs

[Dan Williams <dcbw redhat com>]

On Mon, 2009-07-13 at 00:28 -0700, David Griffith wrote:
> An area has several WAPs with the same SSIDs.  At least one has a bad
> network cable.  This is a problem because NetworkManager will frequently
> roam to one of these bad WAPs.  Even with my notebook sitting perfectly
> still, roaming goes on.  Short of fixing these bad WAPs, the ideal
> solution seems to be blacklisting particular BSSIDs.  How do I do this?

Unfortunately, it's not all that easy.  There's a few layers in the
stack, and each one has to be taught to allow this.  First, the drivers
have the option to roam to *any* AP that has the same SSID and security
settings.  That's the way 802.11 works, and that's a perfectly legal
thing to do.

Second, the supplicant (which can control what AP the driver initially
associates with but not which APs the driver decides to roam to) would
need to be told which APs are blacklisted.

Next, we'd need to store this information somewhere with NetworkManager
too, so that NM could push it to the supplicant.

But at the end of the day, you're much better off just fixing the AP's
flaky cable, or if the AP isn't actually yours, changing the SSID of
your AP to something else.  Seamless 802.11 coverage only works by
allowing devices to roam between APs with the same SSID, and it's
expected that those SSIDs are all connected to the same backing network
(ie, that you can keep the same IP address as you roam around APs in the
same SSID).  All OSs operate this way, Windows, Mac OS X, Linux, etc.

Dan