Re: [lwip-users] How to build a simple TCP [...]

[Kieran Mansley]

On Wed, 2008-07-09 at 12:16 +0200, Antonio de Angelis wrote:
> UPDATE: I've tried to put the server process on a different machine on 
> my home network, and it seems to work. But I want to make it work on the 
> same machine... I attach the wireshark dump of the communication... is 
> it working in the exact way?

The problem here is likely to be the routing table.  When sending a
packet lwIP searches through the list of netifs and compares the IP
address of the interface with the destination address of the packet.  If
none of them match it will use the default, which is usually to send it
out onto the network. 

I'm guessing that you have two different processes, and so two separate
instances of lwIP for your client and server.  Do they share a driver?
Do they share a network card?  Assuming they are structured like this,
it would mean that they would each have a separate routing table and not
know that the other is local.  They would therefore send packets that
should go to the other one out on to the network.

You need something, either in the network, or a software bridge, that
will know that they are both on the same machine and route the packets
back again.  On Linux it is relatively easy to set up a software bridge
to do this, but I'm not sure how you would do it on Windows.

Kieran