Is it time to move QUIC past UDP yet? Does QUIC deserve it's own Protocol number? There's only one byte in IP for protocol number, so it makes sense to limit the number of applications, but I believe QUIC has reached that level.
I'm under the impression that UDP is what makes QUIC valuable, by keeping it compatible with the world's existing network hardware and firewall configurations.
If that issue didn't exist, SCTP would surely see a lot more use.
Hm. Wikipedia tells me that a UDP headers has 4 parts: Source port, dest port, length, and checksum.
I suppose with a new protocol you could ditch the length and checksum, which (I don't know much about networking) might be redundant with the IP header and with TLS respectively. That would save you 4 bytes per packet. Nothing huge.
The reason it uses UDP is that the Internet is full of middleboxes built 10 years ago that won't get any firmware updates for another 10 years, and those boxes love TCP and we're lucky if they even pass UDP and ICMP packets. Anything else might just get dropped, and then you have to fall back. Is UDP underneath QUIC really hurting much?
If that issue didn't exist, SCTP would surely see a lot more use.