wpa_supplicant roaming question

Janusz Dziedzic janusz.dziedzic
Wed Aug 31 22:17:28 PDT 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".


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