[gregfjohnson]

We used LwIP for a project some years ago, and found a very nice way to do system testing.

The project involved multiple microcontrollers communicating over an internal LAN. They used a small embedded kernel named MicroCOS, with LwIP as the IP stack.

We had cross-platform build tools set up, so we could build our stand-alone microprocessor applications either for native execution or with gcc, compiling to x64 code and executable on developer boxes. In the latter case, we implemented the lowest level link-layer part of LwIP using a mock, that used standard TCP/IP! We wrote a small TCP server and would spool up the micro-controller applications, which would then talk to each other on the developer machines as though they were running inside the actual system.

This setup worked really well, and we used it for years during the development effort for the project.