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Last Call Review of draft-ietf-babel-applicability-06
review-ietf-babel-applicability-06-rtgdir-lc-vainshtein-2019-07-03-00

Request Review of draft-ietf-babel-applicability
Requested revision No specific revision (document currently at 10)
Type Last Call Review
Team Routing Area Directorate (rtgdir)
Deadline 2019-07-05
Requested 2019-06-20
Requested by Martin Vigoureux
Authors Juliusz Chroboczek
I-D last updated 2019-07-03
Completed reviews Rtgdir Early review of -01 by Sasha Vainshtein (diff)
Rtgdir Last Call review of -06 by Sasha Vainshtein (diff)
Genart Last Call review of -06 by Joel M. Halpern (diff)
Secdir Last Call review of -06 by Scott G. Kelly (diff)
Assignment Reviewer Sasha Vainshtein
State Completed
Request Last Call review on draft-ietf-babel-applicability by Routing Area Directorate Assigned
Posted at https://mailarchive.ietf.org/arch/msg/rtg-dir/IID1a0AUeaIEKYvrQ42I34MCfBY
Reviewed revision 06 (document currently at 10)
Result Has issues
Completed 2019-07-03
review-ietf-babel-applicability-06-rtgdir-lc-vainshtein-2019-07-03-00
Hello,

I have been selected as the Routing Directorate reviewer for this draft. The
Routing Directorate seeks to review all routing or routing-related drafts as
they pass through IETF last call and IESG review, and sometimes on special
request. The purpose of the review is to provide assistance to the Routing ADs.
For more information about the Routing Directorate, please see
​http://trac.tools.ietf.org/area/rtg/trac/wiki/RtgDir

Although these comments are primarily for the use of the Routing ADs, it would
be helpful if you could consider them along with any other IETF Last Call
comments that you receive, and strive to resolve them through discussion or by
updating the draft.

Document: draft-ietf-babel-applicability-06
Reviewer: Alexander (“Sasha”) Vainshtein
Review Date: 03-Jul-19
IETF LC End Date: 04-Jul-19
Intended Status: Informational

Summary:

I have some minor concerns about this document that I think should be resolved
before publication.

Comments:

I have reviewed the -01 version of the draft two and a half years ago. Since
then the document has undergone massive changes, so that I feel that I have
been reviewing a new document. One thing that remained unchanged, however, was
the readiness of the author to cooperate with the review.  I would like to
express my deep gratitude to Juliusz for that.

The document is very well written and matches my understanding of what an
applicability statement draft for a routing protocol should be. It is not only
easy but also interesting to read (at least for me).

Most of the issues I am raising in this review are in the gray area between
“minor” and “nit”. My classification in this review is, therefore, arbitrary to
some extent, and should be taken with a grain of salt. And at least some of
these issues reflect my personal curiosity.

Major Issues: None found

Minor Issues:

1.       The text in Section 2.3 says: “in order to check the interoperability
of two implementations of Babel, it is enough to verify that the interaction of
the two does not violate the protocol's assumptions.”

a.       This looked just wrong to me – two implementations may preserve all
the protocol assumptions but fail in the interoperability test, e.g., because
encoding of some parameter in one of the PDUs is different

b.       The author has confirmed that this was actually a typo, and has agreed
to remove this text

c.       This is one of the cases where  it is difficult to say whether this is
a minor issue or a nit

2.       The explanation of the BABEL base assumptions in Section 2.2. is very
useful. However, it assumes that the reader has at least some intuitive
understanding of the “routing algebra” notations.

a.       Discussed this point with the author

b.       We have agreed that there is no need to make this document a detailed
tutorial on the subject, nor to indulge in ASCII art (that would be indicative
at best in any case)

c.       Some short explanation, possibly augmented with Informative references
to the relevant research papers, would be sufficient IMHO

3.       The draft mentions 4 independent implementations of BABEL in Section
2.1, but does not say anything about their interoperability. Such information,
if available, should be very useful for the readers. (If no such information is
available as of this moment, I would accept this)

4.       The comparison between BABEL and IS-IS/OSPF in Section 2.4.1 lacks
information about possibility of fast local protection mechanisms (a.k.a. IP
FRR, see, e.g., RFC 5286)

a.       Discussed this point with the author since from my POV such
information could be valuable for the readers that consider deploying BABEL in
their networks

b.       Unfortunately,  the author could not provide an immediate answer one
way or another

5.       Last but not least, a few words about manageability of BABEL would be
useful IMHO.

Nits:

1.       I did not run the nits check on the draft

2.       I think that the work “argue”  in the text in Section 1 “we argue that
there exist niches where Babel is useful and that are not adequately served by
more  mature protocols” is by far too weak (or too modest?). From my POV the
draft goes far beyond arguing.

a.       Discussed this point with the author

b.       The author agrees to change this text to be more definitive,

Hopefully these notes will be useful.

Regards,
Sasha

Office: +972-39266302
Cell:      +972-549266302
Email:   Alexander.Vainshtein@ecitele.com

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