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.
It has been one of the top commercial RTOS network stacks for, I think, 20 years. It moved hands a couple of times and now is supported by the Eclipse Foundation and is MIT-licensed. I'd use it over LwIP.
EDIT: I found an answer[0].
StevePerkins on May 22, 2016 | unvote | next [–]
http://savannah.gnu.org is a hosting site for "official" GNU software (i.e. sponsored by the Free Software Foundation).
http://savannah.nongnu.org is a hosting site for "community" projects that are not sponsored by the FSF.
[0] https://news.ycombinator.com/item?id=11747093
"This making lwIP suitable for use in embedded systems with tens of kilobytes of free RAM and room for around 40 kilobytes of code ROM."
I used to work with TinyTCP back when. What's interesting is if a search for tinytcp turns up a bunch of them. Awesome!
Apparently there's no tiny ipv6 stack?
It is more like the busybox of embedded networking, but with a much more convenient license.