Re: Network Manager reason codes

On Fri, Feb 11, 2011 at 7:06 PM, mike cloaked <mike cloaked gmail com> wrote:
> On Fri, Feb 11, 2011 at 4:30 PM, Sven Nielsen <post svennielsen de> wrote:
>>> >
>>> > That is of course fine - but there are use cases where the two APs are
>>> > both in one's own home - and both have the same ssid.... and that
>>> > presents a problem - at least for me.
>>> >
>> I cannot see the problem either. I think you are talking about the common scenario of having several APs
>> physically distributed on a location which are providing the same WLAN (i.e. all have identical SSID and
>> security settings) to clients. Purpose is to ensure good connectivity around the whole facility.
>> This situation is already handled automatically by Network Manager. Simply define a network configuration,
>> and do NOT set a bssid. This way, NM can (and will) always and automatically connect to the AP with the
>> strongest signal. It will also automatically switch to another AP if you move out of the range of one AP and
>> into the range of another AP. It does this transparently, usually even without any noticeable connection
>> pause.
>> DO NOT set the BSSID (MAC) if you want to roam several APs that provide the same WLAN.
>> To optimize WLAN quality,  configure APs with distinct channels (e.g. 1 and 6) to avoid interferences between
>> both signals.
> I don't know if you have actually tried this in a real life situation
> or not?  However if you do have two access points, and they have the
> same ssid, and the same wpa2 encryption with the same password, but
> are on different channels (let's say one is upstairs and the other is
> downstairs) - then go near access point 1 (let's say it is upstairs) -
> and connect - it works really well and indeed you can see which it has
> connected to by running "iwconfig" as root. This will show the mac
> address of the access point that the wireless is connected to and it
> will confirm it has connected to the access point in the same room.
> The signal remains beautifully at about 100% for as long as you like -
> and all is sweet.
> Now you turn the laptop off and go to work.
> In the evening you come back home, and being tired you bring the
> laptop downstairs and sit on the sofa while you watch the news and
> turn on the laptop which is now near the downstairs access point.
> You find the signal is really weak and the speed of connection is low
> - so you become root and type "iwconfig" - you are amazed that it is
> still connecting to the the upstairs access point as you can still see
> the same mac address listed.   The access point is only 10 feet from
> you and if the laptop would only connect to this one you would get a
> solid and unwavering 100% signal - but NM refuses to co-operate and
> make that connection.
> OK so you are now frustrated - so you go into the NM connections list
> and remove the connection that you already have.  You do "service
> NetworkManager restart" and then when the icon reappears on the gnome
> desktop, you click it, and connect to the same ssid name - now it
> connects immediately to the near one with 100% signal and you use it
> all evening with no problem.
> You shutdown for the night. Next morning you are upstairs and turn on
> the laptop - and it now wants to stick with the one downstairs - which
> is now very weak because you are upstairs! This is my experience with
> more than one laptop - with different wireless cards but all running
> Fedora 14.
> So next time I am in the situation where it refuses to connect to the
> strong signal I disconnect the wireless and edit the connection in NM
> - and add in the MAC address of the near access point into the bssid
> field and save the change.  Now I can connect to the specific access
> point that I want to.
> The point is that I should not need to go through this rigmarole to
> connect to a very much stronger access point which is transmitting the
> same ssid, password and encryption type as another access point with
> the same connection details which is much further away and has a
> substantially and consistently weaker signal.

By the way the whole point of having two access points set up with the
same ssid and encryption is that you just connect to a single ssid
wherever you are in that location - but NM simply does not seem to
behave that way.

If you set different ssid on the two access points, then the behaviour
I described above still happens if there is any small amount if signal
from the access point still seen by the wireless radio - only if there
is no signal at all from the previously connected access point will
the system then forget the previous connection and try to connect to
the near one.

I have indeed heard the reasons for why the logic for making the
initial connection is the way it is currently but in the scenario I
described it would appear to me to be significantly away from the
optimum behaviour -

If my description is not well phrased I will try to describe it a different way?

mike c

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