wpa_supplicant roaming question

Janusz Dziedzic janusz.dziedzic at gmail.com
Thu Sep 1 01:17:28 EDT 2011


2011/8/31 Matt Causey <matt.causey at gmail.com>:
> Ha!  Yeah that's pretty lame on my part.  I was convinced that I'd
> configured the supplicant properly at compile time, but alas I was
> wrong.  I went back and re-compiled and now it works as expected.  :-)
>
> I have another question now...I notice that if the supplicant
> processes a disassociation or deauth, we call
> wpa_supplicant_event_disassoc() (in blacklist.c), which then adds that
> BSSID to a blacklist.  Then, the supplicant can no longer roam to that
> BSSID, even if it is a better choice.
>
> In our use case, we have a large number of access points and they can
> drop offline for maintenance periodically.  What would folks recommend
> we do to keep these BSSID's from becoming permanently blacklisted just
> because they needed to reboot?
>

Seems this is true. Blacklist will be cleared if "No APs found".

In case of our implementation we don't hit this problem. We have
additional CQM signal - beacon_miss - from our driver (nl80211). Count
of beacon_miss is configurable from supplicant when bgscan starts. Our
firmware support this beacon_miss detection - so, it is usefull - we
can roam before deauthenitcation in case someone will switch off AP or
we loose connection.
I think we will push this CQM cfg80211/nl80211 compat-wireless +
hostap implementation soon.

So, in case someone will switch off AP, before we will get
deauthentication we get this beacon_miss event and we have chance to
roam to another APs. If there isn't another APs blacklist will be
cleared because of "No APs found".

BR
Janusz


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