FC1 multiple ethernet interface issue

[Bob Chiodini]

On Tue, 2005-02-15 at 14:39 -0500, David Benigni wrote:
> >>> rchiodin at bellsouth.net 2/15/2005 11:35:01 AM >>>
> >
> > I suspect that the moving of the default route to eth1 and the
> removing
> > of the default route when eth1 is taken down has to do with the
> lookup
> > of the subnet associated with the router and the interface.  The
> default
> > route disappears because the interface with the router's subnet goes
> > down.  The matching algorithm does not take into account that there
> is
> > another interface on the same subnet.  It might be a bug, but most
> > systems are not configured with two interfaces in the same subnet
> > without some sort of bonding or bridging.
> 
> This wouldn't be the first time I'm doing something that is out of the
> norm :)
> 
> > I've tried to sort out Dave's posting (fix your email client to not
> > create a new email thread for each response) and conclude that there
> is
> >one particular host he wants to communicate with on one of the
> >interfaces and everyone else on the other.  Why, and is this host
> >directly connected?  It might be easier to burn a private subnet for
> >this one host and let linux be it's default gateway (NAT and ip
> >forwarding).
> 
> Sorry about the email client, I'm pretty much stuck thought (Novell
> GroupWise).  
> 
> Hears the story of what I'm trying to do.  This box runs DHCPd and
> bind.  For legacy reasons, I have to bind multiple
> ips to the box for an unknown amount of machines that are hard coded to
> the old ip address.  So, initial (and possibly
> flawed) though was to have the new ip I want to roll out 10.x.y.107
> bound to eth0 and bind 10.x.y.114 to eth1.
> Then when all the legacy systems are fixed, I can easily just down
> eth1.  I'd rather mess with eth1 since its not so
> critical as eth0. 
> 
> So, thats the situation.  Any ideas are welcomed. 
> 
> Thanks,
> Dave
> 

Are the hosts using 107 isolated from the hosts on 114?  If not why not
alias the two addresses on the same interface?

ifconfig eth0 10.x.y.107 ... up
ifconfig eth0:1 10.x.y.114 ... up

The gateway would be relative to eth0 and should be available whenever
eth0 is up.  eth0:1 could be brought up and down without affecting the
default gateway setting.

Bob...