Re: [Pce] Genart last call review of draft-ietf-pce-association-diversity-10

worley@ariadne.com (Dale R. Worley) Sun, 26 January 2020 21:04 UTC

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From: worley@ariadne.com (Dale R. Worley)
To: Dhruv Dhody <dhruv.ietf@gmail.com>
Cc: draft-ietf-pce-association-diversity.all@ietf.org, mahend.ietf@gmail.com, pce-chairs@ietf.org, alissa@cooperw.in, julien.meuric@orange.com, db3546@att.com
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Subject: Re: [Pce] Genart last call review of draft-ietf-pce-association-diversity-10
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> Sections 5.4.1 and 5.5 address your comments.
> https://tools.ietf.org/html/draft-ietf-pce-association-diversity-12#section-5.4.1
> https://tools.ietf.org/html/draft-ietf-pce-association-diversity-12#section-5.5

> Thanks. Dale, could you take a look?

My apologies for not responding sooner.

Comparing the latest version, -13, to the one that I reviewed, -10:

Recapitulating my review, the major items were:

- Clarifying the use of the TLV; in particular that non-identical copies
  are attached to multiple LSPs.  This is substantially improved.

- The effect of multiple LSPs with P=1 within a group.  This is
  clarified.  In particular, I see that my previous understanding was
  incorrect.

- Interaction with SVEC.  This discussion is considerably expanded.  I
  do not fully understand it (most likely because I have not read the
  SVEC specification), but it's likely that the authors have covered it
  well.  I note that the new text explains that there may be situations
  that are so complicated that the path computation can not be done.

* However, in regard to the new example:

   o  PCReq with SVEC object with link-diverse bit=1 (LSP1,LSP2) and DAG
      with L=1 (LSP1,LSP3) - link diverse paths between LSP1, LSP2,
      LSP3.  But any future change in LSP2 will have no impact.

As far as I can tell, there is a diversity constraint between LSP1 and
LSP2, and a diversity constraint between LSP1 and LSP3, but there is
none between LSP2 and LAP3 -- this is not quite the same as "link
diverse paths between LSP1, LSP2, LSP3".  In particular, LSP2 and LSP3
might be identical.

The final sentence is unclear to me (probably due to my inexperience);
is it possible to be more exact regarding the reason/manner that such a
change "will have no impact"?

These revisions reasonably resolve my concerns.

Dale