Re: REQUEST: Network Interface Failover and multi-DNS resolution

[Carlos Rodrigues <carlos efr mail telepac pt>]

Mike Fedyk wrote:
> Carlos Rodrigues wrote:
> [snip]
> > Both interfaces use DHCP. But when I unplug the one from which the DNS 
> > servers and default gateway were obtained, nothing changes. My point 
> > is that the second interface should take over completely (the required 
> > settings came through DHCP when it was activated). If the first 
> > interface comes back, it puts things back to normal.
>
>
> Sounds interesting.  File a bug and see what happens.

I'm willing to do that, I just don't know under which package to file 
it. Any suggestions?


> > Well, I didn't knew that. However my point is Fedora's (and other 
> > distros) network scripts should do this (or could do this), possibly 
> > with some configuration options in system-config-network (something 
> > like  an "interface takeover" checkbox and another on an interface to 
> > set it as primary). You can't just ask people to go around adding 
> > routes and tweaking stuff by hand when some of them don't even know 
> > what routes are... That will only make them complain about how it used 
> > to work just fine in Windows, and I don't know about you but I just 
> > hate to hear that. 
>
>
> Yowza.  First of all, this functionality is mostly for routers and 
> requires kernel patches (that sometimes break things) for some 
> functionality.  I doubt that the fedora project wants to add that 
> overhead for the small userbase it would allow them to have.

I don't think this is only a router thing. What I'm talking about is 
just what I mentioned above. Keep the DHCP info for all interfaces, 
change resolv.conf et al with the data from the first interface. If that 
interface *link* goes down (cable unplugged), just pick the data from 
the next interface and apply it. The first one is always the boss, if 
its link goes up, its settings get reapplied.
I don't think this is anything esoteric, we already have something 
keeping an eye on the interface, otherwise we would get no DHCP request 
when the link comes back up. It just has to be changed so that the 
whatever daemon that is monitoring the interface that we consider the 
primary applies the settings for the next interface when it sees its 
interface going down.

Note that I'm not talking about the default gateway going down or some 
failure like that. That's the reason I brought the wireless scenario. 
The fact is our windows users can unplug their laptops from the wired 
LAN (the "staff" network) and move around the building without having to 
restart their network interfaces (the wireless network is part of the 
"students" LAN, a wide-open insecure separate LAN). Our Linux users can't.

Carlos