Very Computer

I just set up a linux router RH9.0 minimal installation with Kernel
2.4.20-8. I'm new to iptables an just wrote a little script resetting
iptables and setting up a masquerading.

This all works fine but then I get loads of messages 'neighbour table
overflow'. After some research I found out this results from an
ouverflowing arp cache (tcpdump -n -i eth0). In allmost all answers it
says that the loopback interface must be configured and up.

Now to me it seems that all is set correctly loopback is up (ifconfig lo
  shows RUNNING) but I still get the messages.

eth0 is the interface to the provider getting an IP via DHCP (cable
modem) and eth1 is the interface to my network with a static IP

Does anyone have an idea

Thanks a lot Daniel