Re: DHCP fall back to link-local? (IPv4)

[Marc Herbert <Marc Herbert gmail com>]

Dan Williams a écrit :
> On Tue, 2009-04-14 at 15:14 +0100, Marc Herbert wrote:
> >   Is there any way to tell Network Manager to fall back on link-local
> > configuration when DHCP fails? Something like:
> >
> >          <entry name="method" type="string">
> >                  <stringvalue>auto,link-local</stringvalue>

> Shouldn't NM just retry DHCP a few times?  What's the use-case here?

The use case is a live CD. I was hoping it could adapt to both 
situations: with or without a DHCP server. But to be honest I think this 
could be useful to any laptop as well, see below.


> > I have browsed mailing list archives and bug trackers for ages but found
> > only old and conflicting information.

According to the list archive, NetworkManager had this feature in the 
past (you can even find the patch in the archive). Not anymore?


To be honest I think this feature is not so exotic considering that some 
people discussing it a few years ago on this list seem to enjoy it very 
much, considering that dhclient seems to have it, and considering that it 
is the default behaviour for both Windows and Mac OS X. To me this 
feature looks like networking made "really easy". Zero configuration at last.

Despite the above I am NOT interested in debating if it should be the 
default behaviour (like it was in the past?).
I am only wondering if it is possible to have this feature at all.


As an alternative solution, maybe I could try to have dhclient (instead 
of NetworkManager) execute avahi-autoipd ? This would require increasing 
the timeout in NetworkManager higher than the one in dhclient, do you 
think this is feasible?


> > By the way I am not able to get rid of the "Auto eth0" phantom
> > connection. Is this a problem? I think it could be related because in the
> > lack of a DHCP server my personal "auto" connection is falling back on
> > this phantom connection (which obviously fails the same).
>
> The "auto eth0" is likely provided by the system-settings-service
> because you don't have a system setting for your device.  If you were to
> create one, it would go away.  You can do that either from your distros
> normal network config tools, or from the connection editor if your
> distro has write support in its system settings plugin.

Thanks for the tips, I will look into that.

Cheers,

Marc

PS: as as side note, Zeroconf is finally bringing to IP what other 
protocol stacks already had 20 years ago.