Comment by gucci-on-fleek 8 hours ago
About 30% percent of traffic to Cloudflare uses HTTP/3 [0], so it seems pretty popular already. For comparison, this is 3× as much traffic as HTTP/1.1.
[0]: https://radar.cloudflare.com/adoption-and-usage#http1x-vs-ht...
At the very least, the benefits of QUIC are very very dubious for low RTT connections like inside a datacenter, especially when you're losing a bunch of hardware support and moving a fair bit of actual work to userspace where threads need to be scheduled etc. On the other hand Cloudflare to backend is not necessarily low RTT and likely has nonzero congestion.
With that said, I am 100% in agreement that the primary benefits of QUIC in most cases would be between client and CDN, whereas the costs are comparable at every hop.
Is CF typically serving from the edge, or serving from the nearest to the server? I imagine it would be from the edge so that it can CDN what it can. So... most of the time it wont be a low latency connection from CF to backend. Unless your back end is globally distributed too.
Also, within a single server, you should not use HTTP between your frontend nginx and your application server - use FastCGI or SCGI instead, as they preserve metadata (like client IP) much better. You can also use them over the network within a datacenter, in theory.
and then cloudflare converts that to http/2 or even 1.1 for the backend