[Int-area] draft-ietf-intarea-extended-icmp-nodeid-05 ietf last call Tsvart review

[Richard Scheffenegger via Datatracker <[e-mail]>]

Document: draft-ietf-intarea-extended-icmp-nodeid
Title: ICMP Message Extension for Originating Node Identification
Reviewer: Richard Scheffenegger
Review result: Almost Ready

This document has been reviewed as part of the transport area review team's
ongoing effort to review key IETF documents. These comments were written
primarily for the transport area directors, but are copied to the document's
authors and WG to allow them to address any issues raised and also to the IETF
discussion list for information.

The main focus of the review was around potential MTU issues - however, these
aspects are covered by the referenced RFC4884 satisfactory;

The primary concern for me is the lack of a length field in the IP Address
sub-object; only two out of 2^16 codepoints are explicitly defined, but it is
unclear how the length would be determined for currently undefined or
erroneously filled out ip address objects with a current implementation in a
future-proof way; putting a potentially variable length object in front of a
length-encoded object (name sub-object) (and subsequent other future sub
objects) seems to make generic extensibility problematic.

If the (only) variable length sub-object would be placed last, and the other
explict and implict length fields remain easily decodeable, this concern would
be alleviated.

When done at the time of IETF Last Call, the authors should consider this
review as part of the last-call comments they receive. Please always CC
[e-mail] if you reply to or forward this review.