Comment by jlokier | Hacker News Reader

Comment by jlokier | Hacker News Reader

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Unfortunately, we may yet see networks that block or slow down QUIC, in a paradoxical attempt to improve performance.

QUIC is designed to hide a lot from the network. But some network nodes use visibility into things like round-trip time, data-in-flight and packet loss for each flow, so they can adjust queuing parameters to optimise for each user. These measurements are easy to get from monitoring TCP, but not QUIC.

The designers of those network nodes may conclude that blocking QUIC (UDP on port 443) and forcing fallback to HTTP/2 over TCP results in better ability to optimise network flows than allowing QUIC to go ahead. All browsers race TCP against QUIC, so a network blocking QUIC shouldn't significantly slow performance compared with just HTTP/2.

This is a hefty bet. The gamble is that you're very good at this, and so you'll deliver better performance with HTTP/2 than the client could have got from HTTP/3, but even if you actually are right by a slim margin you're likely to suffer the same pushback from users as if you were wrong. The only scenarios where this is a smart bet are where competitors allow HTTP/3 and have noticeably worse performance.

If it's close, regardless of which way, you'll get beaten up for disabling HTTP/3, maybe that's unjust but that's how it is.

What users are going to notice? Browsers and almost everything else is going to fallback to TCP and move on, because there are too many broken networks to bother.

Kind of like how most big sites clamp TCP MSS at 1440 instead of 1460; there's too many PPPoE or IPIP tunneled links with broken path mtu, and too many clients without working/enabler path mtu blackhole detection to bother making a fuss about it. Just move on and cry on the inside.

I think people will notice as BYOD gets more and more standard. There is already a situation in my company that everyone who is part of the BYOD initiative doesn't even use their company laptop anymore because everything is so much slower.

They might notice and complain if UDP in general is blocked, but if their webpages load, they won't complain that UDP to port 443 is degraded or blocked.

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