Last Call Review of draft-ietf-rtgwg-policy-model-29
review-ietf-rtgwg-policy-model-29-rtgdir-lc-hardwick-2021-06-26-00

Forwarding to the correct email address for RTG-DIR...

From: Jon Hardwick
Sent: 26 June 2021 11:32
To: rtg-ads@ietf.org; draft-ietf-rtgwg-policy-model.all@ietf.org
Cc: rtgdir@ietf.org; rtgwg@ietf.org
Subject: Rtgdir Last Call review of draft-ietf-rtgwg-policy-model

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-rtgwg-policy-model-29

Reviewer: Jon Hardwick

Review Date: Jun 26th, 2021

Intended Status: Standards Track

Summary:

This document provides a foundational framework for the definition of routing
protocol policies regarding the filtering in / out of routes when they are
imported / exported between routing protocol neighbors and/or routing protocols
and the RIB. Its purpose is to provide a framework which can be augmented by
routing protocols in their policy YANG modules. I think that the document meets
its goal very well.

The document is in good shape. It's clear, well-defined in its scope and easy
to read. I have a few minor concerns that I would like to see addressed before
publication.

Minor Comments:

Section 4.2

Why no match-set-options for neighbor-set?  Is there no application for
differentiating between "any of these neighbors" and "none of these neighbors"?

You can only match on a single interface. Why is that? Was there no use case
for any ANY / INVERT match on a set of interfaces? I am thinking of multihoming
use cases.

"Comparison conditions may similarly use options..." - what do you mean by a
"comparison condition"? The term is not used elsewhere in the document.

Section 5

"If the conditions are not satisfied, then evaluation proceeds to the
   next policy statement"

I think that evaluation also proceeds to the next policy statement if the
conditions were satisfied, but the actions did not include either accept-route
or reject-route. Is that correct? I think it would be worth making that
explicit.

Section 7.2

p21:

      description
        "Mask length range lower bound. It MUST NOT be less than
         the prefix length defined in ip-prefix.";

Why must it not be?  And is there a situation in which it makes sense to allow
it to be greater than the prefix length defined in ip-prefix?  Should there be
a "must" clause to police this constraint?

p29:

            description
              "Policy statements group conditions and actions
               within a policy definition.  They are evaluated in
               the order specified (see the description of policy
               evaluation at the top of this module.";

Missing close-parenthesis in this description.

Best regards

Jon