Re: network manager always deconfigure the ethernet interface when network link is down

[Luc Deschenaux <luc deschenaux mta sunrise ch>]

Le jeudi 10 septembre 2009 à 13:44 -0700, Dan Williams a écrit :
> On Mon, 2009-09-07 at 23:05 +0200, Luc Deschenaux wrote:
> > Hi !
> > 
> > This behaviour is extremely annoying when you connect directly some
> > machine with a crossover cable for netbooting (eg to install a system on
> > a machine without cdrom player, to scan for viruses, backuping, resizing
> > partitions, or whatever)
> > 
> > Or when ethernet interface is connected to a Powered Over Ethernet (POE)
> > device directly through a POE power supply and that you need to reboot
> > it.
> > 
> > The link is lost each time you connect the ethernet cable on another
> > machine and each time you reboot the connected machine. And each time
> > you need to activate the needed configuration again.
> >  
> > Trying to flash the firmware of a handfull of POE devices will quickly
> > make you hate the network manager... especially if you have to
> > reconfigure some routes manually also.
> > 
> > It would be nice to be able to declare an ethernet configuration as
> > being "sticky" so that the interface would not deconfigure itself when
> > the link is down, and not try to reconfigure itself automatically when
> > the link is up again.
> 
> That's something I've discussed with various people, but before we do
> that, we should add a few-second grace-period to the link instead of
> just tearing it down immediately.  How long is the link actually down
> before it comes back up?  I have also encountered this when doing
> crossover stuff but it's always back up in a matter of seconds.
> 
> Dan
> 

For simple reboot it would be yet better, but when reflashing devices,
moving the laptop or connecting another machine, it takes usually more
than just a few seconds before the link is up again

In fact, I need link detection only when using "eth0 auto".

For specific configurations with fixed ip address, I dont see the need
for NM to mandatory bring down the ethernet interface automatically,
even with a delay. (I could want to keep routes or open tcp connections
and reconnect the cable elsewhere)

At least I never need that NM switch to "auto eth0" when the link is up
again, I need to continue with the configuration I did choose.
 
Link detection should be optional, globally or at the connection level
(eg: disconnect automatically)

L:üc: