[Gen-art] Genart last call review of draft-ietf-pce-stateful-pce-lsp-scheduling-13

Robert Sparks via Datatracker <noreply@ietf.org> Tue, 09 June 2020 21:41 UTC

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Subject: [Gen-art] Genart last call review of draft-ietf-pce-stateful-pce-lsp-scheduling-13
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Reviewer: Robert Sparks
Review result: Ready with Issues

I am the assigned Gen-ART reviewer for this draft. The General Area
Review Team (Gen-ART) reviews all IETF documents being processed
by the IESG for the IETF Chair.  Please treat these comments just
like any other last call comments.

For more information, please see the FAQ at

<https://trac.ietf.org/trac/gen/wiki/GenArtfaq>.

Document: draft-ietf-pce-stateful-pce-lsp-scheduling-13
Reviewer: Robert Sparks
Review Date: 2020-06-09
IETF LC End Date: 2020-06-12
IESG Telechat date: Not scheduled for a telechat

Summary: Essentially ready for publication as a Proposed Standard RFC, but with
issues to consider before progressing

Minor Issues:

Section 4.2.2: It's not clear when the computation for a path satisfying the
constraint happens. Is this done once when the periodical LSP arrives, or at
each scheduled interval? If the former, what happens if there is no path
solution for only one of the multiple intervals?

Section 4.4, second paragraph, last sentence: If the path cannot be set, is the
previous LSP left in effect? Or does the failure result in no there being no
scheduled LSPs in effect?

Section 5.1 first paragraph: Why is TCP called out here?

You should be explicit about whether it's ok to have both grace periods and
elastic bounds at the same time. The TLV allows that to happen. I'm not sure
what it would mean, and I suspect it's unlikely that you would have two
implementers compute the consequences the same way.

Section 5.2.1, definition of the R bit: You should call out that relative time
is in seconds (I think?) when the R bit is 1, and you need a discussion
somewhere about the necessity of synchronized clocks and potential problems
with transmission delay when the R bit is 1.

Section 5.2.1, definition of Start-Time: Why must a value of 0 not be used? Is
this true for both R=1 and R=0? For R=1, a start time value of 1 vs a start
time value of 0 may, in practice, be indistinguishable (because of transmission
or processing delay).

In section 5.2.2 at the definition of Repeat-time-length: Please be explicit
about whether this is the interval between the start time of two repetitions or
the interval between the end-time of one repetition and the start of the next
repetition. I think you mean the former.

At section 5.2.1 you say this TLV SHOULD NOT be included unless both PCEP peers
have set the B bit. But in section 6.6, you say MUST NOT. Please choose one. I
think you want both places to say MUST NOT.

Nits:

Introduction, paragraph 3, second sentence: This is hard to read. I suggest
trying to break it into more than one sentence.

Introduction, paragraph 4, third sentence: This is hard to read. Please
simplify.

The document uses both "database" and "data base". Please pick one.

Top of page 7: "In case of former" does not parse. Please clarify.

Section 4.2.2, second paragraph, first sentence: Does not parse. I think it is
missing more than articles.

Section 4.3 at "In both modes": It's not clear what "modes" means here.

It would be worth calling out in section 5.1 that setting PD requires setting B
as specified in 5.2.2.

It would be helpful in 5.2.2 at the definition of Opt: to point forward to the
registry you are creating for its values. It would also be good to be explicit
about what to do if an element receives a TLV with a value here it does not
understand yet.

Section 9.1 ignores leap-years and leap-seconds. It's worth explicitly noting
that.