Re: [arch-d] [Edm] Call for Comment: <draft-iab-use-it-or-lose-it-02> (Long-term Viability of Protocol Extension Mechanisms)

[Brian E Carpenter <[e-mail]>]

I support Joel's point, but here are two more. 

(1) At least for the Internet layer, we have a major problem in deploying new extensions, especially IPv6 extension headers, but this problem goes back 25 years as far as new IPv4 options are concerned. I hoped that section 2.3 "Multi-Party Interactions and Middleboxes" would touch on this, but it doesn't.

Looking back in the draft, I see that it intentionally ducks the question: "This document largely assumes that extensions are not deliberately blocked." But what if they are? That's what firewalls do for a living and it's a major block on innovation. In my world, it's much more significant than the concerns in this draft, and none of the suggested techniques help, as far as I can see.

I'm not suggesting that this document can solve the problem, but can we have a more complete acknowledgement of it than the sentence quoted above?

(2) Again in 2.3 "Multi-Party Interactions and Middleboxes", should there be a discussion of a complex situation where N peers are communicating using protocol P, but each peer potentially supports a different subset of extensions? That gives you up to N^2 possible variants. It's not insoluble, but it needs a bit of care in protocol design (and is different than in a traditional client/server model).

Regards
   Brian Carpenter