Design: Ignored Unknown Frame Types and Intermediaries

[James M Snell <[e-mail]>]

In the current draft, endpoints are required to "ignore" unknown and
unsupported frame types. What's not yet clear, however, is whether
such frames are required to be forwarded on by intermediaries that do
not support them.

In other words, A talks to C via reverse proxy B. A sends a stream
that includes EXTENSION_FRAME_TYPE that is unknown to B. Is B...

A) Required to drop the frame silently without forwarding it on to C
B) Required to always forward the frame on to C
C) Neither, B can do whatever it wants

There is an obvious impact here on the future deployment of new
extension frame types. If the answer is A or C, we'll have to wait on
infrastructure support to use new frame types, which would be
unfortunate.

- James