Early Review of draft-ietf-schc-protocol-numbers-00
review-ietf-schc-protocol-numbers-00-tsvart-early-kuehlewind-2024-08-29-00

First a general comment: It is not clear to me why this is a separate document
and not part of draft-ietf-schc-architecture. draft-ietf-schc-architecture
already specifies the use of a new ether type, protocol number, and port
number, so the registration should be requested in that same document. At
minimum this draft should have draft-ietf-schc-architecture as normative
reference, and more important also the other way around,
draft-ietf-schc-architecture needs to have this draft as a normative reference.

On the port request, the use case is not clear to me. The section on "Basic use
case for SCHC as a UDP port number" is unfortunately empty. The document
mentions firewall traversal as the use case. Please not that RFC6335, however,
does not recommend to use ports for firewall rules. Further a firewall would
usually restrict access based on application information, however, using a
separate port for SCHC that then would carry different kind of application
traffic which is not recognisable for the firewall would probably not help the
firewall. Therefore it would probably more useful to use the same port number
as the compressed packet to enable firewall traversal. But again, the use case
is not described and not clear to me.

Further, as this kind of port usage is not recommended by RFC6335, I would
recommend to request a review by the port registry expert team. But again, at
the moment I do not see a use case and do not recommend to request a separate
port number for SCHC.

Thanks for requesting the early review. I hope my input helps the working group
process.