Re: [lwip-users] problem configuring two Ethernet ports

[Kieran Mansley]

On Wed, 2011-06-22 at 10:58 +0100, rocco brandi wrote:
> now the port0 works properly and the port1 don't answer the
> handshake!!!!
>  
> how is it possible? how can I fix it?

The reason for the change when you re-order the netif_add() statements
will probably be due to whichever netif is being used as the default
one.  

lwIP has some pretty simplistic routing between multiple interfaces, and
this won't have been widely used, so it wouldn't surprise me if there
are issues to be fixed here.

Both the interfaces that you're creating are on the same IP subnet.
This is a rather unusual case, as normally a host would only have a
single interface to each subnet.  Do you see the same problem if you put
the interfaces onto different IP subnets?

To work out how to fix it I would trace the SYN packet that isn't
working properly through lwIP's receive path and see where it is being
dropped.  That should give a clue about what the problem is and how we
can fix it.

Kieran