debian etch 2 nics

I have installed debina etch on a computer with 2 network cards. I want to implment a LAN connection and an outside connection, both fixed IP addresses, so the the systme will be accessibe from the LAN as well as on a dedicated outside IP.

the outside IP address works.

I can ping the nic for the LAN

I cannot ping anything else on the LAN and I cannot ping the LAN nic from any machine on the LAN.

Any ideas why this might be happening, or what to do about it?

BTW, per some posts I read I added eth0 and eth1 and then when rebooting it assigned eth2 and eth3. I found this very strange.

Can anyone help me with this?