Subject: [homenet] Benjamin Kaduk's No Objection on draft-ietf-homenet-babel-profile-06: (with COMMENT)

From: Benjamin Kaduk <[email-masked]>
Date: Tue, 08 May 2018 07:00:10 -0700

Benjamin Kaduk has entered the following ballot position for
draft-ietf-homenet-babel-profile-06: No Objection

When responding, please keep the subject line intact and reply to all
email addresses included in the To and CC lines. (Feel free to cut this
introductory paragraph, however.)

Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html
for more information about IESG DISCUSS and COMMENT positions.

The document, along with other ballot positions, can be found here:
https://datatracker.ietf.org/doc/draft-ietf-homenet-babel-profile/

----------------------------------------------------------------------
COMMENT:
----------------------------------------------------------------------

Section 2.1

   REQ5: a Homenet implementation of Babel MUST use metrics that are of
   a similar magnitude to the values suggested in Appendix A of
   RFC 6126bis.

"MUST" and "similar magnitude" are not a great pairing.

I agree with the secdir reviewer that the link classification is
important, and would suggest a that SHOULD become MUST for "if it is
unable to determine whether a link is wired or wireless, it MUST
make the worst-case hypothesis".

Section 4

I always worry a little bit about the ability to classify links as
"trusted", but there are probably cases where it's valid to do so.
(Whether there are enough cases where it's valid to do so that would
provide enough use cases for this document perhaps will need to wait
for deployment experience.)

I do wonder whether it's worth enumerating the "upper-layer security
protocol"s that HNCP and Babel support, as there are tradeoffs among
the PSK/PKI/TOFU options that the implementor may need to consider.