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Comment by londons_explore | Hacker News Reader

A major benefit of HTTP/3 is the ability to transparently switch from one network connection to another without restarting requests.

You could be midway through a gaming session over websocket, and walk away from your wifi, and you shouldn't notice a glitch.

Nearly nothing else offers that ability, and it's very annoying, especially in offices with hundreds of wifi access points - I should be able to walk down the corridor on a video call without glitchiness!

MPTCP (developed mostly by Apple) offers the same, but Google and Microsoft are holding it back, for some unknown reason.

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This is called WiFi handoff and any enterprise AP deployment worth a damn should have this sorted out, albeit in a proprietary manner. The WiFi standard already has a client establishing a connection to a new AP before giving up the old one at the actual “physical” transport layer, these proprietary extensions exchange existing connection state information over the wired backbone between APs when a client is attempting to move from one to the other so that it can theoretically be a “seamless” experience. In theory, anyway.

Presumably HTTP/3 could do WiFi-> 4G -> WiFi -> 5G -> WiFi... hand-offs as you're moving around.

Genuinely asking, is it actually working or is that like the promises of multiplexing in HTTP/2 that don't really work IRL ?

What's wrong with HTTP/2 multiplexing?

Both share the same attributes: The spec allows them to work, but they require lots of effort on the implementation side to get it right. HTTP/2 require a library which does sane write scheduling and prioritization to make it work.

QUIC handoffs are a lot more complicated. They will require a library which supports all the necessary features. And it will require infrastructure which supports it. Without infrastructure support, packets from the client might get routed to the wrong host after a IP tuple change, and can from there on not associated with the QUIC connection.

My guess is some QUIC deployments will figure out how to make it work - others likely won't, since a lot of efforts is involved.

Tbh consumer AP makers should also get together and support things like fast roaming together.

What does the wifi handoff you mention actually do?

I know of a standard for 802.1X preauthentication, that does 802.1X authentication via old AP before roaming.

If your APs aren't doing NAT or stateful firewall, then there is no state to transfer, except automatic updating of MAC addresses on switches, and the authentication of the client which shouldn't require any cross-communication unless using 802.1X with mentioned preauthentication. You will lose packets in flight while switching, but it shouldn't take long.

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