On Wed, 25 Dec 2013 14:47:48 -0800, Jeff Liebermann
wrote:

~ However ... just guessing ... it would seem to me
~ that, if we use the same SSID, that the STRONGEST
~ should win, and, if one disconnects, it *should*
~ (logically anyway) switch seamlessly over to the
~ stronger signal as the person roams the home.
~
~ http://www.intel.com/support/wireless/wlan/sb/cs-015906.htm
~ Fat chance. That's the way it should work. Instead, what happens is
~ that the client will remain connected to the initial access point, no
~ matter how weak or disgusting a signal it offers. Even if turn off
~ the client device, it will try to reconnect to the same initial access
~ point, even if there's a stronger/better signal with the same SSID
~ evailable. Even if you intentionally disconnect, the client will
~ retain the MAC address of the initial access point. When you try to
~ reconnect, it will try that MAC address first.
~
~ Intel seems to have gotten the clue and offers a setting as to how
~ "aggressive" the client will act in retaining a connection:
~ http://www.intel.com/support/wireless/wlan/sb/CS-030101.htm
~ It's not a total solution, but does work rather well on my various
~ laptops.

I think you're being overly pessimistic, Jeff. The scenario where
you have multiple APs advertising the same SSID on different
non-overlapping channels (where all BSSIDs are bridged to the same L2
broadcast domain), actually works pretty well with most clients
nowadays.

Our large customers often have buildings or campuses with dozens or
even hundreds or thousands of APs all offering the same SSID, and most
modern clients can roam throughout these coverage areas without losing
more than one or two seconds of data connectivity at roam time.

Most clients do offchannel scans for other APs will associated, so
they know what all other APs are out there (although the freshness of
that information will vary.) They are apt to decide to roam based
upon one or more factors like these:

* currently associated BSSID has dropped below a given RSSI threshold
(e.g. below -80 dBm)
* there exists a better BSSID whose RSSI is more than threshold k
stronger than the current one, so let's roam to it (e.g. k=15, so
if the current BSSID's RSSI is -74 dBm and another AP is at -57,
let's go there)
* n consecutive 802.11 retransmissions to the current BSSID have
failed (e.g. where n=32)
* n consective beacons from the current BSSID have been missed (e.g.
where n=10, i.e. ~1 second)

To be sure, in networks that are very large and/or have very stringent
performance requirements (hospitals), exotic roaming schemes involving
L3 tunneling, 802.11r, CCKM, WPA2 PMKID caching etc. can be called
for. But for home/small organization networks, basic WPA2/PSK roaming
across APs within a given SSID will work just fine (again, assuming
that all of these BSSIDs are bridged to the same broadcast domain.)

Cheers,

Aaron