dual-net problem

[Jeff Vian]

On Wed, 2005-05-25 at 19:02 +0100, T. Horsnell wrote:
> Hi all,                    
> I have a system with dual gigabit ethernet ports.    
> I've assigned them each an ip address, and am using  
> tcpdump and ping to check that they work as expected.
> They dont.
>                            
> If I ping, from another box, the address associated with eth1,
> the traffic appears on eth0. This only happens when I ping from 
> another  Linux box - if I ping from one of my Alpha boxes, everything
> works as expected, i.e. pings addressed to the ipaddress    
> allocated to eth0 appear on eth0, and pings to the ipaddress
> allocated to eth1 appear on eth1.
> 
> I'm running FC3 with kernel 2.6.10 on the dual-eth box, and I've
> tried pinging from RH7.3, RH9 and FC3 boxes, all with the same
> result. 
>      
> It appears from the tcpdump output below, that ls1 is returing the
> mac address of the eth1 interface *and* the address of the eth0
> interface. Is this proper? What am I doing wrong?
> 
> Cheers,
> Terry.
> 
You are using 2 interfaces on the same subnet on this machine.  This has
historically never worked reliably.

If you put one of the interfaces on one subnet and the other on a
different subnet I expect it will work better (and as expected).