Re: [Pce] Shepherd's review of draft-ietf-pce-pcep-exp-codepoints

[Dhruv Dhody <[e-mail]>]

Hi Jon,

Thanks for your review. See inline...

From: Pce [mailto:[e-mail]] On Behalf Of Jonathan Hardwick
Sent: 12 November 2017 12:04
To: [e-mail]
Cc: [e-mail]; [e-mail]
Subject: [Pce] Shepherd's review of draft-ietf-pce-pcep-exp-codepoints

Re-sending to the correct DL :)

From: Jonathan Hardwick
Sent: 12 November 2017 12:02
To: '[e-mail]' <[e-mail]<mailto:[e-mail]>>
Cc: '[e-mail]' <[e-mail]<mailto:[e-mail]>>; [e-mail]<mailto:[e-mail]>
Subject: Shepherd's review of draft-ietf-pce-exp-codepoints

Hi there

I am the document shepherd for this draft.  Please find my review of the draft below.

Many thanks for writing this draft.  It looks in good shape overall.  There are just a few clarifications I would like to make before we forward it to the IESG for publication.

Cheers
Jon

Abstract

This sentence about new sub-registries is misleading - the allocation policy for new sub-registries is decided by the drafts that create the sub-registries and does not have to be IETF Review.  I propose:
OLD

   IANA established a new top-level registry to contain all PCEP

   codepoints and sub-registries.  The allocation policy for each new

   registry is by IETF Review.
NEW

   IANA established a top-level registry to contain all PCEP

   codepoints and sub-registries.   This top-level registry contains

   sub-registries for PCEP message, object and TLV types.  The

   allocation policy for each of these sub-registries is IETF Review.
END

[[[Dhruv Dhody]]] Ack.

Introduction

OLD

   The Path Computation Element communication Protocol (PCEP) provides

   mechanisms for Path Computation Elements (PCEs) to perform path

   computations in response to Path Computation Clients (PCCs) requests.
NEW

   The Path Computation Element communication Protocol (PCEP) [RFC5440] provides

   mechanisms for Path Computation Elements (PCEs) to perform path

   computations in response to Path Computation Clients (PCCs) requests.
END
i.e. add reference to RFC 5440.

[[[Dhruv Dhody]]] Ack.

The second paragraph is superfluous - I suggest deleting:

   Further, in order to support use cases described in [RFC8051],

   [I-D.ietf-pce-stateful-pce] specifies a set of extensions to PCEP to

   enable stateful control of MPLS-TE and GMPLS LSPs via PCEP.

   [I-D.ietf-pce-pce-initiated-lsp] describes the setup, maintenance and

   teardown of PCE-initiated LSPs under the stateful PCE model.

[[[Dhruv Dhody]]] Because of the comment for handling the unknown experimental objects for the stateful PCE messages, I think it is better to continue to keep this text. What do you think?

Please apply the same comments I made for the abstract to the following text:
OLD

   IANA established a new top-

   level registry to contain all PCEP codepoints and sub-registries.

   The allocation policy for each new registry is by IETF Review as

   described in [RFC8126].
NEW

   IANA established a top-

   level registry to contain all PCEP codepoints and sub-registries.

   This top-level registry contains sub-registries for PCEP message,

   object and TLV types.  The allocation policy for each of these

   sub-registries is IETF Review.
END

[[[Dhruv Dhody]]] Ack.

Suggested change for clarity:
OLD

   With some recent advancement, there is an enhanced need to experiment

   with PCEP.
NEW

   Recently, there have been rapid advancements in PCE technology, which

   has created an enhanced need to experiment with PCEP.
END

[[[Dhruv Dhody]]] Ack.

Section 5

The following paragraph does not tell the whole story.

   A PCE that does not recognize an experimental PCEP object, will
   reject the entire PCEP message and send a PCE error message with
   Error- Type="Unknown Object" or "Not supported object" as described
   in [RFC5440].

If the P flag is clear in the object header, then the PCE MAY ignore the object instead of generating this error message. Also, you do not discuss what a PCC would do on receipt of a PCUdp or PCInitiate containing an unrecognised experimental object - it is inconsistent that you don't cover these cases.  (FWIW, RFC 8231 is a bit ambiguous about what a PCC should do about the PCUpd. Section 6.2 says that a PCErr should be sent, but then it refers to section 7.3.3, which says that a PCRpt should be sent. Hmmm.)

[[[Dhruv Dhody]]] Yes. How about I update to this -

   If the PCE does not understand or support an experimental object with
   the P flag set in the Object Header, in the Path Computation Request
   message (PCReq), the entire PCEP message is rejected and PCE responds
   with a PCErr message with Error-Type="Unknown Object" or "Not
   supported object" as described in [RFC5440].  Otherwise the object is
   ignored.  In case of stateful PCE messages [RFC8231], the P flag is
   ignored and the unknown object handling is as per the stateful PCE
   extensions.

And let's try to handle the inconsistency in RFC 8231 with an errata perhaps? And handle PCE-initiated during AUTH48?

Also: s/PCE error message/PCErr message/
[[[Dhruv Dhody]]] Ack

Section 7
Nit: add comma after "accidentally"

[[[Dhruv Dhody]]] Ok

Appendix A
I think the text in this Appendix could be clearer.  Here is my suggestion.
OLD

   Based on the feedback from the WG, it was decided to focus only on

   the essentials in the scope of this documents.  For others,

   Experiments can use a new experimental TLV/Object instead.
NEW

   Based on feedback from the PCE WG, it was decided to allocate an

   Experimental code point range only in the message, object and TLV

   sub-registries.  The justification for this decision is that, if

   an experiment finds that it wants to use a new code point in

   another PCEP sub-registry, it can implement the same function using

   a new experimental object or TLV instead.
END

[[[Dhruv Dhody]]] Updated

Other
Please update reference draft-ietf-pce-stateful-pce -> RFC 8231
Please update reference draft-ietf-pce-pce-initiated-lsp-10 -> draft-ietf-pce-pce-initiated-lsp-11

[[[Dhruv Dhody]]] Ack

Diff: https://tools.ietf.org/rfcdiff?url2=https://raw.githubusercontent.com/dhruvdhody-huawei/ietf/master/draft-ietf-pce-pcep-exp-codepoints-03.txt&url1=https://www.ietf.org/id/draft-ietf-pce-pcep-exp-codepoints-02.txt

Thanks for the review!
Regards,
Dhruv