Understanding HTTP/2 Activation Modes on BIG-IP

Hello, CF-Gallia-MS-NOC , thank you for your question. In the capture snippet you pasted, it is ok for BIG-IP not to come back with an ALPN extension header because you're reusing a previous TLS session so the security parameters previously negotiated, including the ALPN extension are re-used.

This could instead be a bug on your client if it's requesting to re-use the same previously negotiated TLS connection but at the same time it wants BIG-IP to re-negotiate the HTTP protocol.

I also have an article about TLS session resumption and TLS renegotiation.

Let me know if you have further questions.