YANG Data Model for Bidirectional Forwarding Detection (BFD)
draft-ietf-bfd-rfc9127-bis-04

[Ballot comment]
Thank you for the work on this document, and for addressing my previous DISCUSS. One minor comment left.

Francesca

        This version of this YANG module is part of RFC 9127; see the
        RFC itself for full legal notices.";

FP: One last occurrence of this text left in Appendix A.1

[Ballot comment]
Thank you for this document.

I'd also like to thank Jeffrey Haas for the well written and comprehensive Document Shepherd writeup -- it answered questions that I would otherwise have asked in the ballot.

[Ballot comment]
Thanks to the Yang Doctors for provided background information with informative links to the discussion.

Changes look good. Others have already pointed out that RFC8177 and RFC9127 need to be added to the normative references.

[Ballot discuss]
Thanks for this specification.

I have noticed couple of potentially normative missing references hence the discuss ballot.

* iana-bfd-types is imported from RFC9127  but missing in the normative reference.
* ietf-key-chain is imported from RFC8177  but missing in the normative reference.

I hope a revised ID  would solve this.

[Ballot discuss]
Thank you for the work on this document.

I have noticed one easy to fix error in the examples, and I additionally have two comments I'd like to talk about before the document is approved - these are non blocking, but answers are appreciated.

Thanks,
Francesca


1. -----

  In this case, an interface named "Bundle-Ether1" of interface type
  "ieee8023adLag" has a desired transmit interval and required receive
  interval set to 10 ms.

FP: But the example actually uses intervals of 100ms:

                 
                    100000
                 
                 
                    100000
                 

[Ballot comment]

2. -----

        This version of this YANG module is part of RFC 9127; see the
        RFC itself for full legal notices.";

FP: Just double checking as I am not sure about what's common for new revisions of existing modules - Should it be this RFC number, rather than or additionally to 9127? (several occurrences in the doc)

3. -----

Section 2.1.1.

FP: I was expecting to see some text about expected behavior if both "min-interval" and any of the other interval parameters are (incorrectly) used at the same time. I expect a value should be discarded, which one?
Also, maybe a bit of a late comment and I will leave it to the authors and wg to decide if including it is worth it, in Section 3 it would have been useful to see one example using the "min-interval".

[Ballot comment]
Document updates RFC9127, but does not cite it as a reference.

Found terminology that should be reviewed for inclusivity; see
https://www.rfc-editor.org/part2/#inclusive_language for background and more
guidance:

* Term "invalid"; alternatives might be "not valid", "unenforceable", "not
  binding", "inoperative", "illegitimate", "incorrect", "improper",
  "unacceptable", "inapplicable", "revoked", "rescinded".

Thanks to Joel Halpern for their General Area Review Team (Gen-ART) review
(https://mailarchive.ietf.org/arch/msg/gen-art/2_6QYcQc4Tflyh0-cr6_e9Gc43s).

-------------------------------------------------------------------------------
NIT
-------------------------------------------------------------------------------
All comments below are about very minor potential issues that you may choose to
address in some way - or ignore - as you see fit. Some were flagged by
automated tools (via https://github.com/larseggert/ietf-reviewtool), so there
will likely be some false positives. There is no need to let me know what you
did with these suggestions.

Document still refers to the "Simplified BSD License", which was corrected in
the TLP on September 21, 2021. It should instead refer to the "Revised BSD
License".

[Ballot comment]
Just a minor nit in section 2.11 as I am unsure whether "This revision is non-backwards compatible" reads well with the "-", I would suggest to use "This revision is not backwards compatible".

-éric

(Via drafts-lastcall@iana.org): IESG/Authors/WG Chairs:

The IANA Functions Operator has completed its review of draft-ietf-bfd-rfc9127-bis-01. If any part of this review is inaccurate, please let us know.

The IANA Functions Operator understands that, upon approval of this document, there are two actions which we must complete.

First, in the ns registry on the IETF XML Registry page located at:

https://www.iana.org/assignments/xml-registry/

six existing namespaces will have their references changed to [ RFC-to-be ]:

ID: yang:ietf-bfd-types

ID: yang:ietf-bfd

ID: yang:ietf-bfd-ip-sh

ID: yang:ietf-bfd-ip-mh

ID: yang:ietf-bfd-lag

ID: yang:ietf-bfd-mpls

Second, in the YANG Module Names registry on the YANG Parameters registry page located at:

https://www.iana.org/assignments/yang-parameters/

six YANG modules will have their references changed to [ RFC-to-be ] and have the associated file updated by the contents of the new RFC:

Name: ietf-bfd-types

Name: ietf-bfd

Name: ietf-bfd-ip-sh

Name: ietf-bfd-ip-mh

Name: ietf-bfd-lag

Name: ietf-bfd-mpls

The IANA Functions Operator understands that these are the only actions required to be completed upon approval of this document.

Note:  The actions requested in this document will not be completed until the document has been approved for publication as an RFC. This message is meant only to confirm the list of actions that will be performed.

Thank you,

Sabrina Tanamal
Lead IANA Services Specialist

The following Last Call announcement was sent out (ends 2022-02-03):

From: The IESG
To: IETF-Announce
CC: bfd-chairs@ietf.org, draft-ietf-bfd-rfc9127-bis@ietf.org, jgs@juniper.net, jhaas@pfrc.org, rtg-bfd@ietf.org
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (YANG Data Model for Bidirectional Forwarding Detection (BFD)) to Proposed Standard


The IESG has received a request from the Bidirectional Forwarding Detection
WG (bfd) to consider the following document: - 'YANG Data Model for
Bidirectional Forwarding Detection (BFD)'
  as Proposed Standard

The IESG plans to make a decision in the next few weeks, and solicits final
comments on this action. Please send substantive comments to the
last-call@ietf.org mailing lists by 2022-02-03. Exceptionally, comments may
be sent to iesg@ietf.org instead. In either case, please retain the beginning
of the Subject line to allow automated sorting.

Abstract


  This document defines a YANG data model that can be used to configure
  and manage Bidirectional Forwarding Detection (BFD).

  The YANG modules in this document conform to the Network Management
  Datastore Architecture (NMDA) (RFC 8342).  This document updates YANG
  Data Model for Bidirectional Forwarding Detection (BFD) (RFC 9127).




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-bfd-rfc9127-bis/



No IPR declarations have been submitted directly on this I-D.

: (1) What type of RFC is being requested (BCP, Proposed Standard, Internet
: Standard, Informational, Experimental, or Historic)? Why is this the proper
: type of RFC? Is this type of RFC indicated in the title page header?

Proposed Standard.

This RFC is intended to define a Yang module for managing the BFD protocol
and its common interactions with other modules using BFD.

: (2) 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:

From the Abstract:

  This document defines a YANG data model that can be used to configure
  and manage Bidirectional Forwarding Detection (BFD).

  The YANG modules in this document conform to the Network Management
  Datastore Architecture (NMDA).

: 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.
:
: Working Group Summary:

The best summary is included as part of the Updates section:

  This version of the draft updates the 'ietf-bfd-types' module to
  define a new feature called 'client-base-cfg-parms and a 'if-feature'
  statement that conditionally includes definition of parameters such
  as 'multiplier' or 'desired-min-tx-interval'.  The feature statement
  allows YANG implementations of protocol such as OSPF, ISIS, PIM and
  BGP, to support both a model where such parameters are not needed,
  such as when multiple BFD sessions are supported over a given
  interface, as well as when they need to be defined per session.  As a
  result, the BFD MPLS module has to use the base-cfg-parms instead of
  client-cfg-parms to be able to include all the parameters
  unconditionally.

: 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?

While the desired YANG changes were very small, this update is occurring a
short time after the original publication of RFC 9127.  It was decided to, as
much as possible, to simply re-issue RFC 9127 to avoid potential confusion
about the authoritative contents of the YANG modules for BFD.

Consultation with the YANG doctors did indicate that a smaller document
containing only the minimum required updates was an option.  However, the
authors and the interested parties in the Working Group participating in the
discussion pushed for the larger document.

The primary consideration that kept this document from being a simple copy and
paste of the original RFC 9127 with the minor necessary changes was the
iana-bfd-types module which was previously delegated to IANA in RFC 9127, and
thus not eligible for re-publication in this document.

: 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, YANG 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?

This module is intended to be leveraged both as the BFD management module along
with providing BFD configuration for other IETF modules.  It was as part of
assessing impacts on other routing protocols that the motivating work for this
update was discovered.

The YANG doctors were consulted as part of this work, but no formal review was
requested.  Since this is largely a republication of RFC 9127, it is presumed
that prior work this is based upon is well reviewed.

: Personnel:
:
: Who is the Document Shepherd?

Jeffrey Haas.

: Who is the Responsible Area Director?

John Scudder.

: (3) Briefly describe the review of this document that was performed by the
: Document Shepherd. If this version of the document is not ready for
: publication, please explain why the document is being forwarded to the IESG.

This document is largely based upon text from a recently shipped RFC.  Thorough
review of the changes have been done both by the shepherd, the authors, and
review has been solicited from the Working Group.

: (4) Does the document Shepherd have any concerns about the depth or breadth
: of the reviews that have been performed?

No.

: (5) Do portions of the document need review from a particular or from broader
: perspective, e.g., security, operational complexity, AAA, DNS, DHCP, XML, or
: internationalization? If so, describe the review that took place.

No.

: (6) Describe any specific concerns or issues that the Document Shepherd has
: 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.

No specific concerns.

: (7) Has each author confirmed that any and all appropriate IPR disclosures
: required for full conformance with the provisions of BCP 78 and BCP 79 have
: already been filed. If not, explain why?

As a re-issue of RFC 9127, prior disclosures apply.

: (8) Has an IPR disclosure been filed that references this document? If so,
: summarize any WG discussion and conclusion regarding the IPR disclosures.

As a re-issue of RFC 9127, prior disclosures apply.

: (9) 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?

BFD is a small working group with deep expertise in the technologies.  YANG
modules are a further specialization and IETF-wide expertise in the language
and modeling considerations is small.  Given these factors, review has been
reasonable.

: (10) 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 publicly available.)

No.

: (11) Identify any ID nits the Document Shepherd has found in this document.
: (See http://www.ietf.org/tools/idnits/ and the Internet-Drafts Checklist).
: Boilerplate checks are not enough; this check needs to be thorough.

No unexpected nits.

: (12) Describe how the document meets any required formal review criteria,
: such as the MIB Doctor, YANG Doctor, media type, and URI type reviews.

The MIB Doctors were polled for the direction for updating RFC 9127 and
feedback was supplied.

: (13) Have all references within this document been identified as either normative or informative?

Yes.

: (14) 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 plan for their completion?

No.

: (15) Are there downward normative references (see RFC 3967)? If so, list
: these downward references to support the Area Director in the Last Call
: procedure.

No.

: (16) Will publication of this document change the status of any existing
: RFCs? Are those RFCs listed on the title page header, listed in the abstract,
: and discussed in the introduction? If the RFCs are not listed in the Abstract
: and Introduction, explain why, and point to the part of the document where
: the relationship of this document to the other RFCs is discussed. If this
: information is not in the document, explain why the WG considers it
: unnecessary.

Yes, this updates RFC 9127.

: (17) Describe the Document Shepherd's review of the IANA considerations
: section, especially with regard to its consistency with the body of the
: document. Confirm that all protocol extensions that the document makes are
: associated with the appropriate reservations in IANA registries. Confirm that
: any referenced IANA registries have been clearly identified. Confirm that
: newly created IANA registries include a detailed specification of the initial
: contents for the registry, that allocations procedures for future
: registrations are defined, and a reasonable name for the new registry has
: been suggested (see RFC 8126).

This document updates prior registrations related to the YANG models previously
associated with RFC 9127, as much as possible.  The prior IANA delegated model
is not updated.

: (18) List any new IANA registries that require Expert Review for future
: allocations. Provide any public guidance that the IESG would find useful in
: selecting the IANA Experts for these new registries.

No new registries.

: (19) Describe reviews and automated checks performed by the Document Shepherd
: to validate sections of the document written in a formal language, such as
: XML code, BNF rules, MIB definitions, YANG modules, etc.

The github repo for this work makes using of pyang and yanglint as part of the
document creation process.

: (20) If the document contains a YANG module, has the module been checked with
: any of the recommended validation tools
: (https://trac.ietf.org/trac/ops/wiki/yang-review-tools) for syntax and
: formatting validation? If there are any resulting errors or warnings, what is
: the justification for not fixing them at this time? Does the YANG module
: comply with the Network Management Datastore Architecture (NMDA) as specified
: in RFC8342?

Yes, see above.

: (1) What type of RFC is being requested (BCP, Proposed Standard, Internet
: Standard, Informational, Experimental, or Historic)? Why is this the proper
: type of RFC? Is this type of RFC indicated in the title page header?

Proposed Standard.

This RFC is intended to define a Yang module for managing the BFD protocol
and its common interactions with other modules using BFD.

: (2) 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:

From the Abstract:

  This document defines a YANG data model that can be used to configure
  and manage Bidirectional Forwarding Detection (BFD).

  The YANG modules in this document conform to the Network Management
  Datastore Architecture (NMDA).

: 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.
:
: Working Group Summary:

The best summary is included as part of the Updates section:

  This version of the draft updates the 'ietf-bfd-types' module to
  define a new feature called 'client-base-cfg-parms and a 'if-feature'
  statement that conditionally includes definition of parameters such
  as 'multiplier' or 'desired-min-tx-interval'.  The feature statement
  allows YANG implementations of protocol such as OSPF, ISIS, PIM and
  BGP, to support both a model where such parameters are not needed,
  such as when multiple BFD sessions are supported over a given
  interface, as well as when they need to be defined per session.  As a
  result, the BFD MPLS module has to use the base-cfg-parms instead of
  client-cfg-parms to be able to include all the parameters
  unconditionally.

: 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?

While the desired YANG changes were very small, this update is occurring a
short time after the original publication of RFC 9127.  It was decided to, as
much as possible, to simply re-issue RFC 9127 to avoid potential confusion
about the authoritative contents of the YANG modules for BFD.

Consultation with the YANG doctors did indicate that a smaller document
containing only the minimum required updates was an option.  However, the
authors and the interested parties in the Working Group participating in the
discussion pushed for the larger document.

The primary consideration that kept this document from being a simple copy and
paste of the original RFC 9127 with the minor necessary changes was the
iana-bfd-types module which was previously delegated to IANA in RFC 9127, and
thus not eligible for re-publication in this document.

: 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, YANG 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?

This module is intended to be leveraged both as the BFD management module along
with providing BFD configuration for other IETF modules.  It was as part of
assessing impacts on other routing protocols that the motivating work for this
update was discovered.

The YANG doctors were consulted as part of this work, but no formal review was
requested.  Since this is largely a republication of RFC 9127, it is presumed
that prior work this is based upon is well reviewed.

: Personnel:
:
: Who is the Document Shepherd?

Jeffrey Haas.

: Who is the Responsible Area Director?

John Scudder.

: (3) Briefly describe the review of this document that was performed by the
: Document Shepherd. If this version of the document is not ready for
: publication, please explain why the document is being forwarded to the IESG.

This document is largely based upon text from a recently shipped RFC.  Thorough
review of the changes have been done both by the shepherd, the authors, and
review has been solicited from the Working Group.

: (4) Does the document Shepherd have any concerns about the depth or breadth
: of the reviews that have been performed?

No.

: (5) Do portions of the document need review from a particular or from broader
: perspective, e.g., security, operational complexity, AAA, DNS, DHCP, XML, or
: internationalization? If so, describe the review that took place.

No.

: (6) Describe any specific concerns or issues that the Document Shepherd has
: 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.

No specific concerns.

: (7) Has each author confirmed that any and all appropriate IPR disclosures
: required for full conformance with the provisions of BCP 78 and BCP 79 have
: already been filed. If not, explain why?

As a re-issue of RFC 9127, prior disclosures apply.

: (8) Has an IPR disclosure been filed that references this document? If so,
: summarize any WG discussion and conclusion regarding the IPR disclosures.

As a re-issue of RFC 9127, prior disclosures apply.

: (9) 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?

BFD is a small working group with deep expertise in the technologies.  YANG
modules are a further specialization and IETF-wide expertise in the language
and modeling considerations is small.  Given these factors, review has been
reasonable.

: (10) 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 publicly available.)

No.

: (11) Identify any ID nits the Document Shepherd has found in this document.
: (See http://www.ietf.org/tools/idnits/ and the Internet-Drafts Checklist).
: Boilerplate checks are not enough; this check needs to be thorough.

No unexpected nits.

: (12) Describe how the document meets any required formal review criteria,
: such as the MIB Doctor, YANG Doctor, media type, and URI type reviews.

The MIB Doctors were polled for the direction for updating RFC 9127 and
feedback was supplied.

: (13) Have all references within this document been identified as either normative or informative?

Yes.

: (14) 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 plan for their completion?

No.

: (15) Are there downward normative references (see RFC 3967)? If so, list
: these downward references to support the Area Director in the Last Call
: procedure.

No.

: (16) Will publication of this document change the status of any existing
: RFCs? Are those RFCs listed on the title page header, listed in the abstract,
: and discussed in the introduction? If the RFCs are not listed in the Abstract
: and Introduction, explain why, and point to the part of the document where
: the relationship of this document to the other RFCs is discussed. If this
: information is not in the document, explain why the WG considers it
: unnecessary.

Yes, this updates RFC 9127.

: (17) Describe the Document Shepherd's review of the IANA considerations
: section, especially with regard to its consistency with the body of the
: document. Confirm that all protocol extensions that the document makes are
: associated with the appropriate reservations in IANA registries. Confirm that
: any referenced IANA registries have been clearly identified. Confirm that
: newly created IANA registries include a detailed specification of the initial
: contents for the registry, that allocations procedures for future
: registrations are defined, and a reasonable name for the new registry has
: been suggested (see RFC 8126).

This document updates prior registrations related to the YANG models previously
associated with RFC 9127, as much as possible.  The prior IANA delegated model
is not updated.

: (18) List any new IANA registries that require Expert Review for future
: allocations. Provide any public guidance that the IESG would find useful in
: selecting the IANA Experts for these new registries.

No new registries.

: (19) Describe reviews and automated checks performed by the Document Shepherd
: to validate sections of the document written in a formal language, such as
: XML code, BNF rules, MIB definitions, YANG modules, etc.

The github repo for this work makes using of pyang and yanglint as part of the
document creation process.

: (20) If the document contains a YANG module, has the module been checked with
: any of the recommended validation tools
: (https://trac.ietf.org/trac/ops/wiki/yang-review-tools) for syntax and
: formatting validation? If there are any resulting errors or warnings, what is
: the justification for not fixing them at this time? Does the YANG module
: comply with the Network Management Datastore Architecture (NMDA) as specified
: in RFC8342?

Yes, see above.