Re: NetworkManager with multiple wireless cards

[Dan Williams <dcbw redhat com>]

On Fri, 2008-06-20 at 21:41 +0100, Andrea wrote:
> Dan Williams wrote:
> > 
> > Sounds like a bug but only in _some_ cases.  If you lock your
> > connections down to a specific card (by setting the card's MAC address
> > in the connection editor), then NM will only use that connection with
> > that card.  If you don't, and the connection is marked with autoconnect,
> > then NM will bring that connection up on any wireless card available if
> > the card can see the AP.  If the connection is not marked autoconnect,
> > then you can manually tell NM which connection to bring up on which
> > card.
> 
> I see.
> I thought that the MAC address was used to change the MAC address and not to select the card.

I intend to add support for that too.

> Wouldn't it be easier to enter the interface name?

No, because interface names are not universally stable; and ideally you
never have to care what the interface name actually is.  At least the
MAC address is often printed on the card/dongle itself, but "wlan11"
never will be.

MAC addresses aren't completely stable either (if you spoof another MAC
for example), but they are stable at boot time and when HAL probes the
device.

> Anyway now I've create 2 entries with different MAC and it works.
> 
> What is misleading is that there are one list of networks per card, so one expects that the network 
> is connected only on the selected card. Shouldn't NM set the MAC address automatically when it 
> create an entry automatically?

Maybe; but if you change wireless cards then you'd have to go back
through and update the MAC in each connection for the new card, which
would suck.  I think that case is /probably/ more frequent than the case
of using two wireless cards in the same machine; who knows.

> Or there should be only 1 list of all networks available regardless of the card.

We can't really do that because cards have different capabilities
(encryption, band, 802.11n).  Leads to situations where it's unclear
which card the connection will be activated on.

Dan

> >> NM does not report it in the Connection Information, but ifconfig shows that both interfaces are 
> >> connected.
> > 
> > Do you mean 'iwconfig'?  The SSID shown in iwconfig doesn't necessarily
> > mean that NM has connected to the AP.  Drivers will sometimes
> > auto-associate with a given AP (but of course you won't have an IP
> > address or routes because NM hasn't brought the connection up), other
> > times there are bugs in the driver that leak an SSID through even when
> > it's not really connected to the AP.  A real association will have both
> > a valid BSSID and a valid SSID as reported by 'iwconfig'.
> 
> No, I mean ifconfig, and what I check is that there is an IP number or not for each interface.
> I don;t use the SSID from iwconfig since as you say it does not mean "connected".
> 
> > Yes, there probably should be a better way than "last one wins".
> > However, if there were a hypothetical "this connection is always
> > default", what should happen if you mark two connections as always
> > default?  last one wins like it currently is?
> 
> Something like a radio button, so there can only be 1.
> 
> Cheers
> 
> Andrea