Re: No inter-AP Roaming?

Quoting Dan Williams <dcbw redhat com>:

On Tue, 2007-12-04 at 15:31 -0500, Derek Atkins wrote:
I'm sitting at the IETF, connected to the 802.11 network..
But as I wander from room to room, NM doesn't roam.  It wont
jump from one AP to another as I move around the conference
facility.  I'll get to my new room and find that I no longer
have any network and then have to wait for a full connection

What gives?  I certainly don't have this problem if I just
let the driver/hardware roam on its own.

Well, NM doesn't control roaming at all, wpa_supplicant and the driver
do.  Sometimes wpa_supplicant will push the BSSID down to the driver
when connecting (not entirely sure when that is) and if the driver
actually follows WEXT (which lots don't) that would cause the driver to
lock to that single BSSID and not switch.  That bit is highly driver
dependent.  It looks like wpa_supplicant will only do this when it has
previously timed out authentication with the station but tries again
(like it should).  It then passes the BSSID down to the association code
which tries to lock the card to that BSSID specifically.


I'm using the iwl3945 driver.  I DO see some authentication timeouts,
which is really weird.. Sometimes to the point where it wont even
successfully authenticate to the card at all and I have to reset.
Very frustrating.

How do I tell whether wpa_supplicant is locking me to a particular
BSSID, and how do I undo that once it's done?



Strangely, it DID just roam as I went from my lunch meeting to
my first after lunch session.  But it's still annoying that it
can drop the session so easily/quickly whereas non-NM will gladly
re-acquire the association as I move between areas, even if I hit
an area of no coverage.

      Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
      Member, MIT Student Information Processing Board  (SIPB)
      URL:    PP-ASEL-IA     N1NWH
      warlord MIT EDU                        PGP key available

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