On Thu, 01 Sep 2005 11:09:16 +0100, Pedro Ramalhais wrote:
> The scheme looks good to me. Wireless cards mostly map to a regular
> network card. Only difference is that you need to do something to
> configure the link to have "carrier detected" and DHCP should only be
> started after "carrier detected" (IFF_RUNNING IIRC).
The fact that DHCP should be only started when carrier is detected is
not wireless-specific.
> Regarding association only on explicit userspace request, that's fixable
> in the drivers (some drivers automatically associate once they're
> ifconfig'ed up, the ipw2x00 drivers have a module parameter to change
> this behaviour).
ipw drivers are broken in this manner as they try to associate right
after modprobe. No card should do anything unless it is explicitly told
so - policy is the matter of user-space, not the kernel. Startup scripts
in distributions are the right place for instructing a card to
associate.
Sure, this is fixable in drivers. And it really needs to be fixed. Even
more, I think it should be forced by ieee80211 layer.
> > And yes, this brings up the problem with firmware loading. It should
> > really be solved, but trying to solve it by requiring to bring the card
> > up before it is configured is the bad way.
>
> Why is it the "wrong way"? I don't see a big problem with this, the card
> is only going to be used after it's UP. The only problem i see is that
> it doesn't behave exactly like most network drivers, where they are able
> to detect a link even when they're DOWN. Is there a good reason for a
> card to do anything even when it's DOWN?
You seem to agree with me :-) A card in DOWN state should do nothing. In
particular, it shouldn't associate.
But it should be configurable. And it is really necessary that we can
tell a card that we are done with configuration so it can associate. The
easiest place for doing this is bringing the card to UP state.
> Right, that would need a new interface where all parameters are passed
> at once,
Then you will lose the possibility of having default parameters.
> or keep the existing interface and add another just to
> explicitly associate.
Is there any reason not to do this by bringing the card up ("ifconfig up")?
> Besides that, there should also be a way to configure if you want to
> auto-associate to new access points if the old access point becomes
> unavailable or with a weaker signal than the new one, or if you want to
> manually associate, ex: association is done once and never tried again
> until you tell it to do so. The manual association would be a good thing
> for a wireless managed, where it would have the work of handling new
> networks, APs becoming unavailable and available again, etc.
Yes. If the new AP is in the same ESS, that should be done automatically
(if not explicitly disabled e.g. by setting of explicit BSSID). Of
course you may sometimes want to force reassociation manually - and
there should be some call available for this. (Maybe setting BSSID while
the card is running should force reassociation?)
If you want to change SSID (i.e. associate to a completely new network)
I can imagine that you will be forced to bring the card down, change
settings and bring it up again (but I don't insist on it as it is not
necessary - bringing the card down and up again can be done internally
by ieee80211 layer in such case).
--
Jiri Benc
SUSE Labs
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