[En-Nut-Discussion] IP forwarding added

[Nathan Moore]

> Yes, in my test environment I forwarded IP packets between PPP and Ethernet.
> Actually I didn't change anything regarding multiple interfaces, it worked out of the box.
> I didn't expect any problems when using two (or more) Ethernet ports.


Years ago I used a system based on the Ethernut 2 design to do this,
but I had to heavily modify the IP stack to do so.  I don't remember
which version of Nut/OS was my starting point.

My forwarding was TCP and UDP (and associated ICMP) port based.  One
issue that I remember having to deal with when connecting multiple
network interfaces was that the IP address was cached in EEPROM in the
same location for all interfaces, so that was overwriting the same
location a lot.  I don't think that this was the right behavior for
PPP anyway, so I took that out.

I did get it to work with 3 interfaces after that (PPP, Ethernet, and
a custom interface).  The limiting factor for Ethernet <-> PPP always
seemed to be the PPP baud rate.

Nathan