“Every significant element of TCP, from its stream orientation to its expectation of in-order packet delivery, is wrong for the datacenter.”
TCP was built for long-haul links where packets wander. Inside a datacenter, its byte streams and in-order delivery waste most of what modern networks can do. Ousterhout says no patch will fix it and pitches Homa instead. The catch is that Homa isn’t compatible with the TCP API every application already uses. Better protocols lose to installed bases all the time.