When it comes to the performance of internet-facing applications, HTTP/3 is no small step over HTTP/2: Google’s own roll-out of HTTP/3 reduced Search latency by 2%, reduced video rebuffer times on YouTube by 9%, and improved throughput on mobile devices by 7%. So today, we’re excited to bring support for HTTP/3 to all Google Cloud customers using Cloud CDN and HTTPS Load Balancing. With HTTP/3 support, you’ll see real-world improvements to your streaming video, image serving and API scaling behind our global infrastructure—all without having to change your applications.
What is HTTP/3?
HTTP/3 is a next-generation internet protocol, and is built on top of QUIC, a protocol we developed and contributed to the IETF, the standards organization in charge of maintaining internet protocols. Together, HTTP/3 and QUIC address previous challenges with HTTP/2 around head-of-line-blocking, security (TLS 1.3 is foundational to QUIC), and reliability over unreliable connections. The original Google QUIC (we call it ‘gQUIC’) will be phased out at the end of 2021, as the number of IETF QUIC clients is quickly surpassing those that support gQUIC.
Importantly, your end users can benefit from HTTP/3 today: the latest versions of Mozilla Firefox, Google Chrome, and Apple’s iOS Safari all support HTTP/3 and/or plan to enable it by default in the next couple of months, as do popular libraries such as Cronet and libcurl.
To use HTTP/3 for your applications, you can enable it on your external HTTPS Load Balancers via the Cloud Console or the gcloud SDK with a single click.
Clients that don’t yet support HTTP/3 such as older browsers or networking libraries won’t be negatively impacted: HTTP/3 uses the Alt-Svc HTTP header to allow clients to “opt in” if they support the protocol. Those clients will continue to negotiate HTTP/2 or HTTP/1.1 as appropriate.
In the coming weeks, we’ll bring HTTP/3 to more users when it’s enabled by default for all Cloud CDN and HTTPS Load Balancing customers: you won’t need to lift a finger for your end users to start enjoying improved performance. If you want to learn more about how Cloud CDN works, check out our overview video, and keep an eye on our release notes to keep up with new features.
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