Hello

I have been selected to do a routing directorate “early” review of this
draft.
​https://datatracker.ietf.org/doc/draft-ietf-ospf-segment-routing-msd/

The routing directorate will, on request from the working group chair,
perform an “early” review of a draft before it is submitted for publication
to the IESG. The early review can be performed at any time during the
draft’s lifetime as a working group document.

For more information about the Routing Directorate, please see ​
http://trac.tools.ietf.org/area/rtg/trac/wiki/RtgDir

Document: draft-ietf-ospf-segment-routing-msd.txt
Reviewer: Tal Mizrahi
Review Date: April 2018
Intended Status: Standards Track

*Summary:*
This document is basically ready for publication, but has a couple of
issues and a few nits that should be considered prior to being submitted to
the IESG.

*Comments:*

   - The Security Considerations should be more detailed. The reference to
   RFC 7770 is a good start, but please add more details about potential
   attacks. For example, what happens if there is a spoofed MSD with a low MSD
   value? What is the impact of such an attack?
   - Section 3:
      - The description of the Length field says “minimum of 2”, implying
      it can be higher than 2.
      On the other hand, the Value field: “consists of a 1 octet sub-type
      (IANA Registry) and 1 octet value.”, which implies that the
Length is equal
      to 2.
      Please align the two descriptions, i.e., if flexibility for future
      sub-types is required, please change the description of Value to allow
      longer values.
      - The comment applies to Section 4 as well.

*Nits:*

   - The term “minimum MSD”, which translates to “minimum maximum SID
   Depth” should be explained.
   - The term “maximum MSD” appears twice in the document, which seems
   either redundant, or a typo (did you mean minimum MSD?).
   - The acronym SID should be spelled out on its first use.
   - The acronyms RI and LSA should be added to the Terminology subsection.
   - Section 1.1.1 and Section 2 are both titled “Terminology”. It would be
   best to merge Section 1.1 into Section 2, and avoid the duplicate title.
   - “each node/link a given SR path” -> “each node/link of a given SR path”
   - “nodes and links which has been configured” -> “nodes and links that
   have been configured”
   - “laso”->”also”
   - “Other Sub-types other than defined” -> “Sub-types other than defined”



Cheers,
Tal Mizrahi.