HTTP/3 in the frontend and HTTP/2 in the backend

[kobedan]

Hi,

I'm lost. I have two virtual servers, one listening for HTTP/2 and one listening to HTTP/3. With the HTTP/2 one the requests to the backend pool members happen over HTTP/2 but with the HTTP/3 profile it falls back to HTTP/1.1

Does anyone have any idea how I could solve this problem?

[shsingh]

Hi @kobedan 

Are you on v15? As there is no support for serverside H/3 and QUIC: https://support.f5.com/csp/article/K60235402

--snippet from the article--

In this experimental implementation of HTTP/3 and QUIC, the BIG-IP system offers the following features and requirements:

• To enable proxy support for HTTP/3, you must configure the virtual server with HTTP/3 and QUIC profiles as well as enable the HTTP MRF Router setting. 
• You must use HTTP/3 and QUIC together. Using QUIC without HTTP/3 is not supported.
• Using QUIC and HTTP/3 on the server side is not supported in this implementation.
• On the Configuration utility, you must set the Protocol option to UDP. The QUIC and HTTP/3 profile options will then be available for selection.
• QUIC works only with TLSv1.3. The BIG-IP system provides the default clientssl-quic profile that you should use as a parent profile to customize your own Client SSL profile.

[kobedan]

Hi @shsingh 

I'm using version 16. 

My problem is not that I can't use HTTP/3 on the server side, i know that that won't work. But the problem is that when using HTTP/3 client side the server side isn't using HTTP/2. I know that HTTP/2 on the server side works because when using HTTP/2 on the client side I have HTTP/2 on the server side working with the same HTTP/2 profile.

When forcing HTTP/2 always on by switching activation mode from ALPN to always I get this error in my Chrome browser:

And this error on Firefox:

[shsingh]

Hey @kobedan 

Thanks for the explanation and screenshot. 

My guess is that H/3 on clientside will mean drop to H/1 on serverside... in a similar way to in "gateway mode" H/2 on clientside does H/1 on serverside.

What you're expecting is to have serverside drop to H/2 instead of H/1

The solution article does not explain the expected behaviour in that scenario. Give me a day to see what I can test and report back. I would also encourage a support case on this to understand the expected behaviour. DM me your support case so I can also track it internally.