The previous sections describe how HTTP/2 is configured and works with a Virtual Service type of HTTP-HTTP/2-HTTPS – you select the Enable HTTP/2 Stack option under the Virtual Service's Advanced Properties, which enables HTTP/2 processing on the client side and HTTP/1.1 on the server side.

The LoadMaster also supports passing unmodified HTTP/2 traffic directly to the back-end Real Servers. This behavior is enabled by selecting the HTTP/2 Pass-through Virtual Service Type when creating a Virtual Service.

An HTTP/2 Pass-through Virtual Service simply passes incoming HTTP/2 traffic to the back-end servers without modification. Since the HTTP/2 traffic is not modified, it remains HTTP/2 traffic – it is not sent to the back-end servers as HTTP/1.1 traffic (as is done with the Enable HTTP/2 Stack option).

The HTTP/2 Pass-through alternative offers better performance, at the cost of having no ability to inspect and modify the encrypted traffic at the LoadMaster – which means the LoadMaster cannot perform operations like examining and modifying header values. This is why an HTTP/2 Pass-through Virtual Service provides fewer options than an HTTP-HTTP/2-HTTPS Virtual Service with the Enable HTTP/2 Stack enabled.