Why not UDP

Except that the costs (as I understand it) basically destroy all the benefits! It's called UDP/IP for a reason (although we normally drop the IP bit, same as TCP). The IP stands for Internet Protocol, which is designed to go through routers etc etc. Homa is designed for a LAN, where typically you're routing MAC addresses through a switch, not IP addresses through a router.

So yes, the fundamental idea behind Homa and UDP is very similar. But the *implementation* is very different, and that's the whole point. And the whole point of Homa is that - by deleting all that overhead of routing - it gets a massive speedup.

As the original article said, don't try to run Homa over a WAN. It's the (in)ability to be efficient over the WAN, that helps it be the Cheetah in the server room.

Cheers,
Wol