There is a talk by Kirk McKusick on YouTube[1] where he tells about that time, and IIRC, Bill Joy got his hands on an early version of BBN's code, started hacki

There is a talk by Kirk McKusick on YouTube[1] where he tells about that time, and IIRC, Bill Joy got his hands on an early version of BBN's code, started hacking on it and put it into BSD. BBN and DARPA were not very amused, but by the time BBN's stack was finished, the BSD version had better performance and/or lower packet loss, so it stuck. Apparently Mike Muuss compared the two implementations, and his recommendation to go with Bill Joy's code was the decisive factor. [1] https://www.youtube.com/watch?v=ds77e3aO9nA https://www.youtube.com/watch?v=ds77e3aO9nA - I think that's the one