Path Computation Element Communication Protocol (PCEP) Requirements and Protocol Extensions in Support of Global Concurrent Optimization
draft-ietf-pce-global-concurrent-optimization-10

[Ballot comment]
It's probably worth checking that the update to  didn't get out of step with the other -pce- documents (similar to -pce-of- while in genart). I don't think there's a problem, but someone more familiar with the whole set with me should look.

If MU and mU are intended to be integers that can only be between 0 and 100, the text would benefit from explicitly stating that. (or is having an MU of 255% ok?)

[Ballot discuss]
I have reviewed draft-ietf-pce-global-concurrent-optimization-10.
Overall, the document looks good, but I have one question:

In Section 5.5, the text says the GC object has 24 reserved bits,
but these are not shown in Figure 3. Which is correct?

IANA questions/comments:

- This document requests registrations in registries that don't exist,
and we can't tell whether a) the document gives the wrong title for the
registries or b) the registries will be created by another document
that IANA isn't aware of. If the latter, can you tell us which
document creates those registries? If the former, can you clarify the
registry name? This is particularly important for Actions 3 and 6.

Action 1 (Section 9.1):

- Is this the correct registry?

Upon approval of this document, IANA will make the following
assignments in the "RP Object Flag Field" at
http://www.iana.org/assignments/pcep/pcep.xhtml

Bit Description Reference
--- ----------- ---------
tbd(11) Report the request order [RFC-pce-global-concurrent-optimization-08]
tbd(12) Make-before-break [RFC-pce-global-concurrent-optimization-08]


Action 2 (Section 9.2):

Upon approval of this document, IANA will make the following
assignments in the "PCEP TLV Type Indicators" registry at
http://www.iana.org/assignments/pcep/pcep.xhtml

Value Description Reference
----- ----------- ---------
tbd(5) Order TLV [RFC-pce-global-concurrent-optimization-08]


Action 3 (Section 9.3):

Upon approval of this document, IANA will make the following
assignment in the "PCE-CAP-FLAGS TLV Types," which has been
misidentified or which has yet to be created, presumably at
http://www.iana.org/assignments/pcep/pcep.xhtml

FLAG Meaning Reference

9 Global Concurrent Optimization (GCO) [RFC-pce-global-concurrent-optimization-08]


Action 4 (Section 9.4):

Upon approval of this document, IANA will make the following
assignments in the "PCEP Objects" registry at
http://www.iana.org/assignments/pcep/pcep.xhtml

Object Name Reference
Class

tbd(24) GLOBAL-CONSTRAINTS
[RFC-pce-global-concurrent-optimization-08]
Object-Type
1: Global Constraints
[RFC-pce-global-concurrent-optimization-08]
2-15: Unassigned


Action 5 (Section 9.5):

Upon approval of this document, IANA will make the following
assignment in the "PCEP-ERROR Object Error Types and Values" registry at
http://www.iana.org/assignments/pcep/pcep.xhtml

Error
Type Meaning Reference

5 Policy violation
Error-value=tbd(5):
[RFC-pce-global-concurrent-optimization-08]
Global concurrent optimization not allowed

tbd(15) Global Concurrent Optimization Error
[RFC-pce-global-concurrent-optimization-08]
Error-value=0:
Unassigned
Error-value=1:
Insufficient memory
[RFC-pce-global-concurrent-optimization-08]
Error-value=2:
Global concurrent optimization not supported
[RFC-pce-global-concurrent-optimization-08]
Error-value=3-255:
Unassigned


Action 6 (Section 9.6):

Upon approval of this document, IANA will make the following
assignments in the "NO-PATH-VECTOR TLV Flag Field" (?) registry at
http://www.iana.org/assignments/pcep/pcep.xhtml

Bit
Number Name Reference

tbd(6) No GCO migration path found
[RFC-pce-global-concurrent-optimization-08]
tbd(7) No GCO solution found
[RFC-pce-global-concurrent-optimization-08]


We understand the above to be the only IANA Actions for this document.

Proto-write-up for draft-ietf-pce-global-concurrent-optimization-08.txt

Intended status : Standards Track

> (1.a)  Who is the Document Shepherd for this document?  Has the
>        Document Shepherd personally reviewed this version of the
>        document and, in particular, does he or she believe this
>        version is ready for forwarding to the IESG for publication?

Adrian Farrel is the document shepherd.
He has personally reviewed the I-D and believes it is ready for
forwarding to the IESG for publication.

> (1.b)  Has the document had adequate review both from key WG members
>        and from key non-WG members?  Does the Document Shepherd have
>        any concerns about the depth or breadth of the reviews that
>        have been performed?

The I-D has had a good level of discussions and review in the PCE
working group. It has not had review in any wider forums, but none was
deemed necessary or appropriate.

> (1.c)  Does the Document Shepherd have concerns that the document
>        needs more review from a particular or broader perspective,
>        e.g., security, operational complexity, someone familiar with
>        AAA, internationalization or XML?

No concerns.

> (1.d)  Does the Document Shepherd have any specific concerns or
>        issues with this document that the Responsible Area Director
>        and/or the IESG should be aware of?  For example, perhaps he
>        or she is uncomfortable with certain parts of the document, or
>        has concerns whether there really is a need for it.  In any
>        event, if the WG has discussed those issues and has indicated
>        that it still wishes to advance the document, detail those
>        concerns here.  Has an IPR disclosure related to this document
>        been filed?  If so, please include a reference to the
>        disclosure and summarize the WG discussion and conclusion on
>        this issue.

The document is sound.

An IPR disclosure was made just as the proto write-up was being done.
It can be found at https://datatracker.ietf.org/ipr/1061. This
disclosure appears to be somewhat peripheral to the content of the I-D
although each person will need to make their own assessment.

The working group was immediately polled for its opinion, but there
were no comments requesting that we halt progress. The WG has been
informed that it should continue to consider the issue during IETF last
call and IESG review.

> (1.e)  How solid is the WG consensus behind this document?  Does it
>        represent the strong concurrence of a few individuals, with
>        others being silent, or does the WG as a whole understand and
>        agree with it?

Consensus is good and relatively broad.
There was previously some significant concern expressed by one of the
chairs with respect to the applicability of this draft and its effect
on network stability. However, the authors worked closely with the
chairs to derive text that addressed the issues and both chairs now
support the work.

> (1.f)  Has anyone threatened an appeal or otherwise indicated extreme
>        discontent?  If so, please summarise the areas of conflict in
>        separate email messages to the Responsible Area Director.  (It
>        should be in a separate email because this questionnaire is
>        entered into the ID Tracker.)

No threats. No discontent.

> (1.g)  Has the Document Shepherd personally verified that the
>        document satisfies all ID nits?  (See
>        http://www.ietf.org/ID-Checklist.html and
>        http://tools.ietf.org/tools/idnits/).  Boilerplate checks are
>        not enough; this check needs to be thorough.  Has the document
>        met all formal review criteria it needs to, such as the MIB
>        Doctor, media type and URI type reviews?

All checks made.

> (1.h)  Has the document split its references into normative and
>        informative?  Are there normative references to documents that
>        are not ready for advancement or are otherwise in an unclear
>        state?  If such normative references exist, what is the
>        strategy for their completion?  Are there normative references
>        that are downward references, as described in [RFC3967]?  If
>        so, list these downward references to support the Area
>        Director in the Last Call procedure for them [RFC3967].

References split.
No downrefs.

> (1.i)  Has the Document Shepherd verified that the document IANA
>        consideration section exists and is consistent with the body
>        of the document?  If the document specifies protocol
>        extensions, are reservations requested in appropriate IANA
>        registries?  Are the IANA registries clearly identified?  If
>        the document creates a new registry, does it define the
>        proposed initial contents of the registry and an allocation
>        procedure for future registrations?  Does it suggest a
>        reasonable name for the new registry?  See [RFC2434].  If the
>        document describes an Expert Review process has Shepherd
>        conferred with the Responsible Area Director so that the IESG
>        can appoint the needed Expert during the IESG Evaluation?

The document defines small protocol enhancements to PCEP. The PCEP
specification is progressing through the RFC Editor process and no
formal IANA registry has yet been created. Nevertheless, this I-D
requests further allocations from the PCEP registry that IANA will
create and manage.

The IANA section of this I-D uses the same language as the PCEP
specification and, in particular, uses the same sub-registry names.

> (1.j)  Has the Document Shepherd verified that sections of the
>        document that are written in a formal language, such as XML
>        code, BNF rules, MIB definitions, etc., validate correctly in
>        an automated checker?

The message formats are described in relatively simple BNF as per the
PCEP specification. This is defined in a referenced document.

No automated checker has been used. The document shepherd has reviewed
the BNF by hand.

> (1.k)  The IESG approval announcement includes a Document
>        Announcement Write-Up.  Please provide such a Document
>        Announcement Write-Up.  Recent examples can be found in the
>        "Action" announcements for approved documents.  The approval
>        announcement contains the following sections:
>
>        Technical Summary
>          Relevant content can frequently be found in the abstract
>          and/or introduction of the document.  If not, this may be
>          an indication that there are deficiencies in the abstract
>          or introduction.


The Path Computation Element (PCE) is a network component,
application, or node that is capable of performing path computations
at the request of Path Computation Clients (PCCs).  The PCE is
applied in Multiprotocol Label Switching Traffic Engineering
(MPLS-TE) networks and in Generalized MPLS (GMPLS) networks to
determine the routes of Label Switched Paths (LSPs) through the
network.  In this context a PCC may be a Label Switching Router
(LSR), a Network Management System (NMS), or another PCE.  The Path
Computation Element Communication Protocol (PCEP) is specified for
communications between PCCs and PCEs, and between cooperating PCEs.

When computing or re-optimizing the routes of a set of TE LSPs
through a network it may be advantageous to perform bulk path
computations in order to avoid blocking problems and to achieve more
optimal network-wide solutions.  Such bulk optimization is termed
Global Concurrent Optimization (GCO).  A GCO is able to
simultaneously consider the entire topology of the network and the
complete set of existing TE LSPs, and their respective constraints,
and look to optimize or re-optimize the entire network to satisfy all
constraints for all TE LSPs.  A GCO may also be applied to some
subset of the TE LSPs in a network.  The GCO application is primarily
a Network Management System (NMS) solution.

While GCO is applicable to any simultaneous request for multiple TE
LSPs (for example, a request for end-to-end protection), it is not
envisaged that global concurrent reoptimization would be applied in a
network (such as an MPLS-TE network) that contains a very large
number of very low bandwidth or zero bandwidth TE LSPs since the
large scope of the problem and the small benefit of concurrent
reoptimization relative to single TE LSP reoptimization is unlikely
to make the process worthwhile.  Further, applying global concurrent
reoptimization in a network with a high rate of change of TE LSPs
(churn) is not advised because of the likelihood that TE LSPs would
change before they could be globally reoptimized.  Global
reoptimization is more applicable to stable networks such as
transport networks or those with long-term TE LSP tunnels.

This document provides application-specific requirements and the PCEP
extensions in support of GCO applications.

>        Working Group Summary
>          Was there anything in WG process that is worth noting?  For
>          example, was there controversy about particular points or
>          were there decisions where the consensus was particularly
>          rough?

WG has good consensus with no disputes or disagreements.
Concerns over the impact of this work on network stability (as a
result of "churn") have been addressed with suitable text to describe
the concerns and advise the operator about the risk.

>        Document Quality
>          Are there existing implementations of the protocol?  Have a
>          significant number of vendors indicated their plan to
>          implement the specification?  Are there any reviewers that
>          merit special mention as having done a thorough review,
>          e.g., one that resulted in important changes or a
>          conclusion that the document had no substantive issues?  If
>          there was a MIB Doctor, Media Type or other expert review,
>          what was its course (briefly)?  In the case of a Media Type
>          review, on what date was the request posted?

There are two known implementations of the protocol extensions described
in this document.