For which protocols? TCP/IP itself is network byte order all the way down to the bottom of the jar.

For example, Cap'n Proto and QUIC are both little endian.

TCP is becoming increasingly less relevant, although I don't know if it'll ever actually disappear.

Capn Proto and QUIC are are layer 6 and 7 (presentation and application protocols respectively). Quic is built on top of UDP.

Layers 3-4 (network, transport) are both big-endian - IP packet headers and TCP/UDP headers use big-endian format.

This means you can't have an IP stack (let alone TCP/UDP, Quic, Capn Proto) that's little-endian all the way through without breaking the internet.

Outside the webdev bubble, it's pretty much QUIC that is irrelevant - it's just another UDP based application protocol.

UDP is an implementation detail of QUIC, just a way to give IP-ish functionality to userspace. In practice, QUIC is a TCP alternative.

The OSI layer model is not necessarily as relevant as it used to be.

You're kind of saying "look over here!" but I'm not that easily distracted. You said "Which will also become a historical artifact as new protocols are made to use little endian". It's never going to become a historical artifact in our lifetimes. As the peer poster pointed out, QUIC itself has big-endian header fields. IPv4/IPv6 both use big-endian at layer 3.

The OSI layer model is extremely relevant to the Cisco network engineers running the edges of the large FAANG companies, hyperscalers etc. that connect them to the internet.

I was wrong about QUIC, for some reason I was sure I'd read it's little-endian.

I'm just pointing out that UDP is an extremely thin wrapper over IP and the preferred way of implementing new protocols. It seems likely we'll eventually replace at least some of our protocols and deprecate old ones and I was under the impression new ones tended to be little endian.

Foolishly, QUIC is not little-endian [1]. The headers are defined to be big-endian. Though, obviously, none of UDP, TCP, or QUIC define the endianness of their payload so you can at least kill it at that layer.

[1] https://www.rfc-editor.org/rfc/rfc9000.html#name-notational-...

Oh really? I must’ve misread.