Enabling HTTP3 for a VCL

General
1

I’m experimenting with enabling http3 for an (existing) test CDN service, following the instructions in Enabling HTTP/3 for Fastly services
I’ve enable http3 in the VCL config, and activated the TLS config for “HTTP/3 & TLS v1.3 + 0RTT” in the TLS domain activations section. But nevertheless is seems that it’s not possible to establish an http3 connection to the service.

Am I missing something? My understanding is it doesn’t matter about the origin services, the VCL service should terminate the HTTP3 connection?

2

Hey @PaulRudin :wave:

Since it sounds like you’ve added the relevant configuration to the service, I’m wondering if this is because your DNS records need updating to refer to the “HTTP/3 & TLS v1.3 + 0RTT” configuration that you activated.

Screenshot 2024-06-25 at 07.30.46
Screenshot 2024-06-25 at 07.30.462848×1416 357 KB

See the above example from my own account in which the second TLS configuration (which supports HTTP/3) has different a CNAME and A records to the first one.

Hopefully this helps, otherwise your best bet would be to reach out to support@fastly.com who can take a look at the config and investigate further

3

So I appear to have 5 different TLS configurations, how do I know which one is relevant? Two of them mention HTTP3.

4

… or to put it another way, how do we know what the link is between “subscriptions” and “configurations”, since they both have their own page?

5

OK, I have now got it working by changing the relevant CNAME record at route53.

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