Long-Lived Graceful Restart for BGP
draft-ietf-idr-long-lived-gr-06

[Ballot comment]
The shepherd writeup misses correctly answering a few important questions: (a) Why is this the right document status? (b) Why is it recommending designated experts for a registry that doesn't require any?  (c) The answer to question 10 appears to suggest there's an IDR area, when there isn't.

[Ballot discuss]
These two DISCUSSes should be easy to resolve :)


        The following text in Section 4.2 of the GR specification [RFC4724] no longer applies:
        [...]
        and the following procedures are specified instead:
        [...]

Shouldn't this be indicated with an Updates: 4724 clause ?



The well-known BGP community "LLGR_STALE" and "NO_LLGR" used by this document
are listed in the IANA registry as defined by draft-uttaro-idr-bgp-persistence
which expired in 2019.  If this is an early allocation, this value might vanish
from the registry ? I'm not sure what the exact process would be to ensure those
values remain in the registry and that these can be safely used by this document.

Then in the IANA Considerations, it claims _this_ document is adding these entries
to the IANA Registry?

        This document introduces a new BGP well-known community
        "LLGR_STALE" for marking long-lived stale routes, and another
        well-known community "NO_LLGR" to mark routes that should not
        be retained if stale.

So I guess that removes my concern for these entries expiring. I am assuming that this
document taking over these entries is okay, I just wanted to confirm that with the
responsible AD, the IETF Secretariat and IANA :-)

[Ballot discuss]
These two DISCUSSes should be easy to resolve :)


        The following text in Section 4.2 of the GR specification [RFC4724] no longer applies:
        [...]
        and the following procedures are specified instead:
        [...]

Shouldn't this be indicated with an Updates: 4724 clause ?



The well-known BGP community "LLGR_STALE" and "NO_LLGR" used by this document
are listed in the IANA registry as defined by draft-uttaro-idr-bgp-persistence
which expired in 2019.  If this is an early allocation, this value might vanish
from the registry ? I'm not sure what the exact process would be to ensure those
values remain in the registry and that these can be safely used by this document.

Then in the IANA Considerations, it claims _this_ document is adding these entries
to the IANA Registry?
        This document introduces a new BGP well-known community
        "LLGR_STALE" for marking long-lived stale routes, and another
        well-known community "NO_LLGR" to mark routes that should not
        be retained if stale.

So I guess that removes my concern by these entries expiring. I am assuming that this
document taking over these entries is okay, I just wanted to confirm that with the
responsible AD, the IETF Secretariat and IANA :-)

[Ballot discuss]
These two DISCUSSes should be easy to resolve :)


        The following text in Section 4.2 of the GR specification [RFC4724] no longer applies:
        [...]
        and the following procedures are specified instead:
        [...]

Shouldn't this be indicated with an Updates: 4724 clause ?



The well-known BGP community "LLGR_STALE" and "NO_LLGR" used by this document
are listed in the IANA registry as defined by draft-uttaro-idr-bgp-persistence
which expired in 2019.  If this is an early allocation, this value might vanish
from the registry ? I'm not sure what the exact process would be to ensure those
values remain in the registry and that these can be safely used by this document.

Then in the IANA Considerations, it claims _this_ document is adding these entries
to the IANA Registry?
        This document introduces a new BGP well-known community
        "LLGR_STALE" for marking long-lived stale routes, and another
        well-known community "NO_LLGR" to mark routes that should not
        be retained if stale.

So I guess that removes my concern by these entries expiring. I am assuming that this
document taking over these entries is okay, I just wanted to confirm that with the
responsible AD and the IETF Secretariat :-)

[Ballot comment]
I'll note that I personally think that this proposal provides many many opportunities for shooting oneself in the foot, but you do point that out quite clearly in the Deployment and Security Considerations sections, so... well... um... if consenting adults decide to do this, it ain't my place to say No.

I **do** think that the document would be improved with some better explanations of under what conditions the 4095 second (1.1h!) GR time might not be sufficient. It does handwave some examples like VPLS and Flowspec, but I'm not at all convinced that if I e.g deploy filters using Flowspec that the "right" answer isn't for these to revert if the neighbor isn't back after 1h.


I'd also like to thank Bo Wu for the OpsDir review (https://datatracker.ietf.org/doc/review-ietf-idr-long-lived-gr-02-opsdir-lc-wu-2022-12-01/) and the authors for responding.

[Ballot comment]
# GEN AD review of draft-ietf-idr-long-lived-gr-06

CC @larseggert

Thanks to Stewart Bryant for the General Area Review Team (Gen-ART) review
(https://mailarchive.ietf.org/arch/msg/gen-art/h5dRb_BAviIWxKRasRMp-Y4AUDE).

## Comments

Thanks for a well-written document!

### Inclusive language

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

* Term `traditional`; alternatives might be `classic`, `classical`, `common`,
  `conventional`, `customary`, `fixed`, `habitual`, `historic`,
  `long-established`, `popular`, `prescribed`, `regular`, `rooted`,
  `time-honored`, `universal`, `widely used`, `widespread`

## Notes

This review is in the ["IETF Comments" Markdown format][ICMF], You can use the
[`ietf-comments` tool][ICT] to automatically convert this review into
individual GitHub issues. Review generated by the [`ietf-reviewtool`][IRT].

[ICMF]: https://github.com/mnot/ietf-comments/blob/main/format.md
[ICT]: https://github.com/mnot/ietf-comments
[IRT]: https://github.com/larseggert/ietf-reviewtool

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

The IANA Functions Operator has completed its review of draft-ietf-idr-long-lived-gr-05. 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 three actions which we must complete.

First, in the Capability Codes registry located at:

https://www.iana.org/assignments/capability-codes/

the existing early registration for:

Value: 71
Description: Long-Lived Graceful Restart (LLGR) Capability

will be made permanent and its reference changed to [ RFC-to-be ].

Second, in the Border Gateway Protocol (BGP) Well-known Communities registry located at:

https://www.iana.org/assignments/bgp-well-known-communities/

the existing early registrations for:

Attribute Value: 0xFFFF0006
Attribute: LLGR_STALE

and

Attribute Value: 0xFFFF0007
Attribute: NO_LLGR

will be made permanent and their references changed to [ RFC-to-be ].

Third, a new registry is to be created called the Long-lived Graceful Restart Flags for Address Family registry. The new registry will be located on the Border Gateway Protocol (BGP) Parameters registry page located at:

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

The registration policy for the new registry will be Standards Action as defined by RFC 8126. The contents of the registry are eight bits. The initial contents of the new registry are as follows:

Bit Position Name Short Name Reference
------------+---------------------+------------+-------------
0 Preservation of state F [ RFC-to-be ]
1-7 Unassigned

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.

For definitions of IANA review states, please see:

https://datatracker.ietf.org/help/state/draft/iana-review

Thank you,

David Dong
IANA Services Specialist

The following Last Call announcement was sent out (ends 2023-07-13):

From: The IESG
To: IETF-Announce
CC: andrew-ietf@liquid.tech, draft-ietf-idr-long-lived-gr@ietf.org, idr-chairs@ietf.org, idr@ietf.org, jhaas@juniper.net
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (Support for Long-lived BGP Graceful Restart) to Proposed Standard


The IESG has received a request from the Inter-Domain Routing WG (idr) to
consider the following document: - 'Support for Long-lived BGP Graceful
Restart'
  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 2023-07-13. 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


  In this document, we introduce a new BGP capability termed "Long-
  lived Graceful Restart Capability" so that stale routes can be
  retained for a longer time upon session failure than is provided for
  by BGP Graceful Restart (RFC 4724).  A well-known BGP community
  "LLGR_STALE" is introduced for marking stale routes retained for a
  longer time.  A second well-known BGP community, "NO_LLGR", is
  introduced to mark routes for which these procedures should not be
  applied.  We also specify that such long-lived stale routes be
  treated as the least-preferred, and their advertisements be limited
  to BGP speakers that have advertised the new capability.  Use of this
  extension is not advisable in all cases, and we provide guidelines to
  help determine if it is.

  We update RFC 6368 by specifying that the LLGR_STALE community must
  be propagated into, or out of, the path attributes exchanged between
  PE and CE.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-idr-long-lived-gr/



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

: Document History
:
: 1.  Does the working group (WG) consensus represent the strong concurrence of a
:    few individuals, with others being silent, or did it reach broad agreement?

Support within the Working Group Last Call was modest, but from individuals
from a wide variety of organizations.  There was no dissent.

: 2.  Was there controversy about particular points, or were there decisions where
:    the consensus was particularly rough?

In general, respondents to the WGLC did not offer technical feedback on
advancing this document.  This document represents a long-deployed extension to
BGP implemented by several vendors.

The document shepherd raised the singular point that the multicast VPN
procedures did not seem to have implementations available.  The authors chose
to remove this section from the draft.  The removal of that section was not
controversial.

The remainder of the shepherd's technical comments were minor and swiftly
addressed in a document update.

: 3.  Has anyone threatened an appeal or otherwise indicated extreme discontent? If
:    so, please summarize 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.

: 4.  For protocol documents, are there existing implementations of the contents of
:    the document? Have a significant number of potential implementers indicated
:    plans to implement? Are any existing implementations reported somewhere,
:    either in the document itself (as RFC 7942 recommends) or elsewhere
:    (where)?

There are multiple implementations, including Cisco, FRR, Juniper, and Nokia.

: Additional Reviews
:
: 5.  Do the contents of this document closely interact with technologies in other
:    IETF working groups or external organizations, and would it therefore benefit
:    from their review? Have those reviews occurred? If yes, describe which
:    reviews took place.

This feature is localized to BGP and would not benefit from such additional scrutiny.

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

Not Applicable.

: 7.  If the document contains a YANG module, has the final version of the module
:    been checked with any of the recommended validation 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 RFC 8342?

This document does not contain a YANG module or extension to such a module.

The BGP YANG draft in IDR is intended to advance to Working Group Last Call
during 2022.  Since that module covers base BGP functionality, extensions such
as this one that are not covered in the base module will need augmentation
modules in the future.  The BGP YANG authors are taking specific care to permit
such augmentations in the design of the base module.

: 8.  Describe reviews and automated checks performed to validate sections of the
:    final version of the document written in a formal language, such as XML code,
:    BNF rules, MIB definitions, CBOR's CDDL, etc.

Not applicable.

: Document Shepherd Checks
:
: 9.  Based on the shepherd's review of the document, is it their opinion that this
:    document is needed, clearly written, complete, correctly designed, and ready
:    to be handed off to the responsible Area Director?

Yes.

: 10. Several IETF Areas have assembled lists of common issues that their
:    reviewers encounter. For which areas have such issues been identified
:    and addressed? For which does this still need to happen in subsequent
:    reviews?

IDR does not currently have such a checklist.

: 11. What type of RFC publication is being requested on the IETF stream (Best
:    Current Practice, Proposed Standard, Internet Standard,
:    Informational, Experimental or Historic)? Why is this the proper type
:    of RFC? Do all Datatracker state attributes correctly reflect this intent?

Proposed Standard.

: 12. Have reasonable efforts been made to remind all authors of the intellectual
:    property rights (IPR) disclosure obligations described in BCP 79? To
:    the best of your knowledge, have all required disclosures been filed? If
:    not, explain why. If yes, summarize any relevant discussion, including links
:    to publicly-available messages when applicable.

All disclosures have been made:
Bruno deCraene:
https://mailarchive.ietf.org/arch/msg/idr/T3RdmSAped0kBPVek72WmYnGQmg/

Jim Uttaro:
https://mailarchive.ietf.org/arch/msg/idr/aWR7JmdQLVwhJsYru1xn5IGFveQ/

John Scudder:
https://mailarchive.ietf.org/arch/msg/idr/gmIm0rPo2iZTC_itPLk2MDpb9b4/

Enke Chen:
https://mailarchive.ietf.org/arch/msg/idr/HR2NiY0R0Ap7DzKMxRTefERjfmQ/


: 13. Has each author, editor, and contributor shown their willingness to be
:    listed as such? If the total number of authors and editors on the front page
:    is greater than five, please provide a justification.

Yes.

There are four authors.

: 14. Document any remaining I-D nits in this document. Simply running the idnits
:    tool is not enough; please review the "Content Guidelines" on
:    authors.ietf.org. (Also note that the current idnits tool generates
:    some incorrect warnings; a rewrite is underway.)

The id-nits tool was run and found no relevant errors.  It currently flags the
update to RFC 6368 as not being in the abstract, but this seems to be a bug in
the detection of the Abstract section spanning more than one paragraph.

: 15. Should any informative references be normative or vice-versa? See the IESG
:    Statement on Normative and Informative References.

The references are appropriate.

: 16. List any normative references that are not freely available to anyone. Did
:    the community have sufficient access to review any such normative
:    references?

Not applicable.

: 17. Are there any normative downward references (see RFC 3967 and BCP
:    97) that are not already listed in the DOWNREF registry? If so,
:    list them.

Not applicable.

: 18. Are there normative references to documents that are not ready to be
:    submitted to the IESG for publication or are otherwise in an unclear state?
:    If so, what is the plan for their completion?

Not applicable.

: 19. Will publication of this document change the status of any existing RFCs? If
:    so, does the Datatracker metadata correctly reflect this and are those RFCs
:    listed on the title page, in the abstract, and discussed in the
:    introduction? If not, explain why and point to the part of the document
:    where the relationship of this document to these other RFCs is discussed.

Yes.  This will update RFC 6368 and is correctly flagged in the document.

: 20. 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 aspects of the document requiring IANA assignments are
:    associated with the appropriate reservations in IANA registries. Confirm
:    that any referenced IANA registries have been clearly identified. Confirm
:    that each newly created IANA registry specifies its initial contents,
:    allocations procedures, and a reasonable name (see RFC 8126).

The IANA section has been reviewed as part of the shepherd's WGLC review.
Several RFC 1997 BGP Communities had been previously allocated and are
appropriately referenced in the IANA registry.  An additional registry that is
not currently present in IANA has been requested as part of the shepherd review
covering the "Long-lived Graceful Restart Flags for Address Family".  This
additional request addresses the only open IANA Considerations issue.

: 21. List any new IANA registries that require Designated Expert Review for
:    future allocations. Are the instructions to the Designated Expert clear?
:    Please include suggestions of designated experts, if appropriate.

The new "Long-lived Graceful Restart Flags for Address Family" registry is
being requested as "Standards Action".  The IDR Chairs would be an appropriate
Designated Expert for this registry.

: Document History
:
: 1.  Does the working group (WG) consensus represent the strong concurrence of a
:    few individuals, with others being silent, or did it reach broad agreement?

Support within the Working Group Last Call was modest, but from individuals
from a wide variety of organizations.  There was no dissent.

: 2.  Was there controversy about particular points, or were there decisions where
:    the consensus was particularly rough?

In general, respondents to the WGLC did not offer technical feedback on
advancing this document.  This document represents a long-deployed extension to
BGP implemented by several vendors.

The document shepherd raised the singular point that the multicast VPN
procedures did not seem to have implementations available.  The authors chose
to remove this section from the draft.  The removal of that section was not
controversial.

The remainder of the shepherd's technical comments were minor and swiftly
addressed in a document update.

: 3.  Has anyone threatened an appeal or otherwise indicated extreme discontent? If
:    so, please summarize 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.

: 4.  For protocol documents, are there existing implementations of the contents of
:    the document? Have a significant number of potential implementers indicated
:    plans to implement? Are any existing implementations reported somewhere,
:    either in the document itself (as RFC 7942 recommends) or elsewhere
:    (where)?

There are multiple implementations, including Cisco, FRR, Juniper, and Nokia.

: Additional Reviews
:
: 5.  Do the contents of this document closely interact with technologies in other
:    IETF working groups or external organizations, and would it therefore benefit
:    from their review? Have those reviews occurred? If yes, describe which
:    reviews took place.

This feature is localized to BGP and would not benefit from such additional scrutiny.

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

Not Applicable.

: 7.  If the document contains a YANG module, has the final version of the module
:    been checked with any of the recommended validation 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 RFC 8342?

This document does not contain a YANG module or extension to such a module.

The BGP YANG draft in IDR is intended to advance to Working Group Last Call
during 2022.  Since that module covers base BGP functionality, extensions such
as this one that are not covered in the base module will need augmentation
modules in the future.  The BGP YANG authors are taking specific care to permit
such augmentations in the design of the base module.

: 8.  Describe reviews and automated checks performed to validate sections of the
:    final version of the document written in a formal language, such as XML code,
:    BNF rules, MIB definitions, CBOR's CDDL, etc.

Not applicable.

: Document Shepherd Checks
:
: 9.  Based on the shepherd's review of the document, is it their opinion that this
:    document is needed, clearly written, complete, correctly designed, and ready
:    to be handed off to the responsible Area Director?

Yes.

: 10. Several IETF Areas have assembled lists of common issues that their
:    reviewers encounter. For which areas have such issues been identified
:    and addressed? For which does this still need to happen in subsequent
:    reviews?

IDR does not currently have such a checklist.

: 11. What type of RFC publication is being requested on the IETF stream (Best
:    Current Practice, Proposed Standard, Internet Standard,
:    Informational, Experimental or Historic)? Why is this the proper type
:    of RFC? Do all Datatracker state attributes correctly reflect this intent?

Proposed Standard.

: 12. Have reasonable efforts been made to remind all authors of the intellectual
:    property rights (IPR) disclosure obligations described in BCP 79? To
:    the best of your knowledge, have all required disclosures been filed? If
:    not, explain why. If yes, summarize any relevant discussion, including links
:    to publicly-available messages when applicable.

All disclosures have been made:
Bruno deCraene:
https://mailarchive.ietf.org/arch/msg/idr/T3RdmSAped0kBPVek72WmYnGQmg/

Jim Uttaro:
https://mailarchive.ietf.org/arch/msg/idr/aWR7JmdQLVwhJsYru1xn5IGFveQ/

John Scudder:
https://mailarchive.ietf.org/arch/msg/idr/gmIm0rPo2iZTC_itPLk2MDpb9b4/

Enke Chen:
https://mailarchive.ietf.org/arch/msg/idr/HR2NiY0R0Ap7DzKMxRTefERjfmQ/


: 13. Has each author, editor, and contributor shown their willingness to be
:    listed as such? If the total number of authors and editors on the front page
:    is greater than five, please provide a justification.

Yes.

There are four authors.

: 14. Document any remaining I-D nits in this document. Simply running the idnits
:    tool is not enough; please review the "Content Guidelines" on
:    authors.ietf.org. (Also note that the current idnits tool generates
:    some incorrect warnings; a rewrite is underway.)

The id-nits tool was run and found no relevant errors.  It currently flags the
update to RFC 6368 as not being in the abstract, but this seems to be a bug in
the detection of the Abstract section spanning more than one paragraph.

: 15. Should any informative references be normative or vice-versa? See the IESG
:    Statement on Normative and Informative References.

The references are appropriate.

: 16. List any normative references that are not freely available to anyone. Did
:    the community have sufficient access to review any such normative
:    references?

Not applicable.

: 17. Are there any normative downward references (see RFC 3967 and BCP
:    97) that are not already listed in the DOWNREF registry? If so,
:    list them.

Not applicable.

: 18. Are there normative references to documents that are not ready to be
:    submitted to the IESG for publication or are otherwise in an unclear state?
:    If so, what is the plan for their completion?

Not applicable.

: 19. Will publication of this document change the status of any existing RFCs? If
:    so, does the Datatracker metadata correctly reflect this and are those RFCs
:    listed on the title page, in the abstract, and discussed in the
:    introduction? If not, explain why and point to the part of the document
:    where the relationship of this document to these other RFCs is discussed.

Yes.  This will update RFC 6368 and is correctly flagged in the document.

: 20. 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 aspects of the document requiring IANA assignments are
:    associated with the appropriate reservations in IANA registries. Confirm
:    that any referenced IANA registries have been clearly identified. Confirm
:    that each newly created IANA registry specifies its initial contents,
:    allocations procedures, and a reasonable name (see RFC 8126).

The IANA section has been reviewed as part of the shepherd's WGLC review.
Several RFC 1997 BGP Communities had been previously allocated and are
appropriately referenced in the IANA registry.  An additional registry that is
not currently present in IANA has been requested as part of the shepherd review
covering the "Long-lived Graceful Restart Flags for Address Family".  This
additional request addresses the only open IANA Considerations issue.

: 21. List any new IANA registries that require Designated Expert Review for
:    future allocations. Are the instructions to the Designated Expert clear?
:    Please include suggestions of designated experts, if appropriate.

The new "Long-lived Graceful Restart Flags for Address Family" registry is
being requested as "Standards Action".  The IDR Chairs would be an appropriate
Designated Expert for this registry.