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Re: HTTP/3 options

From: Daniel Stenberg via curl-library <>
Date: Thu, 12 Jan 2023 22:55:58 +0100 (CET)

On Thu, 12 Jan 2023, Dmitry Karpov via curl-library wrote:

> Daniel, a question about the "Happy eyeballs everything!" section in the
> blog. Is the "happy eyeballs" interval between H3 and H2 going to be
> controlled by the same option as the interval between IPv6 and IPv4 or there
> will be a special option for that?

I imagine that we start out with a fixed mostly arbitrary delay that we think
works and then if someone insists and gives a good reason we make it an

> I am asking because QUIC in H3 is supposed to provide a very quick
> connection start, so the HE interval between H3 and H2 can be made shorter
> than between IPv6 and IPv4, thus allowing faster switch to H2/H1 if UDP is
> blocked.

Sure, but we also have to accept that you might try a h3 request to an old
server on the other side of the globe via a slow network.

A 50-100 ms delay maybe?

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Received on 2023-01-12