IETF publishes HTTP/3 RFC to move the Web from TCP to UDP • The Register


The Internet Engineering Task Force on Monday published the RFC for HTTP/3, the third version of the Hypertext Transport Protocol.

As explained in an IETF summary:

Let’s unpack that a bit.

QUIC stands for “Quick UDP Internet Connections” and was created by Google and revealed in 2013. Google developed QUIC to address the fact that Transport Control Protocol (TCP) needs a few round trips to establish a connection and start to move data. It therefore produces long round-trip times which can result in a poor user experience. QUIC instead uses User Datagram Protocol (UDP) to transport traffic. UDP reduces the number of round trips between client and server, thus speeding things up. That matters a lot to mobile networks, which when Google concocted QUIC were slow and sparse. Mobile networks remain a highly contested resource, so anything that speeds them up is welcome.

Google liked QUIC so much that in 2020 the advertising giant bakes in its own Chrome browser and activated it on its own services – a combo that, in theory, makes the experience of selling your digital soul to Google more enjoyable (or at least involves fewer moments of delay and frustration than selling your soul to others).

Cloudflare has implemented QUIC as an option in 2018.

Microsoft also liked QUIC so much that they made their own version and made it open source. NGINX added support for HTTP/3.

But as the prevalence of QUIC grew, much of the world’s data traffic was still carried over HTTP/2, which relies on TCP. Slow, wordy, flaky, TCP.

So when networking boffins started considering HTTP/3, in 2016, mapping it to QUIC made sense as a way to speed up the web. But they also made sure that HTTP/3 and HTTP/2 could coexist.

On Monday, June 6, their efforts yielded RFC 9114 – a proposed standard.

The Complete RFC contains over 20,000 words and explains HTTP/3 in extraordinary detail.

HTTP/3 is already making waves. Cloudflare has revealed that his observations on the web suggest that it is already the second most popular version of HTTP, but still far behind HTTP/2.

Cloudflare HTTP Version Prevalence Data

Cloudflare HTTP Version Prevalence

HTTP/3 is the blue line. Click to enlarge

Cloudflare analysis suggests that 80% of HTTP/3 traffic comes from the Chrome browser. What a surprise.

The publication of the HTTP/3 RFC is not the end of the matter, because RFC stands for “Request for Comments” – which means that HTTP/3 is waiting for final approval.

That’s unlikely to happen, because so many web heavyweights helped create HTTP/3 that its passage to becoming a standard is almost assured.

But HTTP/3 still has critics and competitors. Apache has delayed adding the protocol to its web server, arguing that its own HTTPD is doing a good job. Privacy advocates continue to worry about QUIC, as do networking enthusiasts who have found the promised speed boost elusive. HTTP/3 is therefore not a panacea.

But the debut of RFC 9114 is a big moment nonetheless. As Cloudflare put it: “Today, a set of Internet standards were released that streamline and modernize the definition of HTTP.”

There are not many days when such statements can be made. ®


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