[Soekris] Using Multiple Ethernet Ports

[David Burke]

I have a Soekris NET4501 board running with Linux and I want to be able to
use more than one (of the three) Ethernet ports simultaneously.  I have
configured each port (eth0, eth1 and eth2) so that each one has a unique IP
address and MAC address.  Whenever I have more than one of these ports
enabled, the other port(s) do not seem to work (i.e. don't respond to ping).
Can anyone tell me what might be causing this or how to eliminate it.