An Update to the tcpControlBits IP Flow Information Export (IPFIX) Information Element
draft-ietf-opsawg-rfc7125-update-07

Received changes through RFC Editor sync (changed state to RFC, created became rfc relationship between draft-ietf-opsawg-rfc7125-update and RFC 9565, changed IESG state to RFC Published)

[Ballot comment]
Maybe add reference for "reduced-size encoding" which is not defined in this document and no pointer is given to elsewhere on what this means.


NITS:

[IPFIX] reference is broken. It contains: https://datatracker.ietf.org/doc/html/%3Chttps://www.iana.org/assignments/ipfix/ipfix.xhtml

[Ballot comment]
# Éric Vyncke, INT AD, comments for draft-ietf-opsawg-rfc7125-update-06

Thank you for the work put into this document. ROA are indeed critical for the security and stability of the Internet. As usual for a -bis document, I reviewed only the diffs.

Please find below some non-blocking COMMENT points (but replies would be appreciated even if only for my own education), and one nit.

Special thanks to Joe Clarke for the shepherd's detailed write-up including the WG consensus *and* the justification of the intended status.

I hope that this review helps to improve the document,

Regards,

-éric

# COMMENTS

## Misleading file name

While not important at this stage, this document appears more like a 7125-bis than a 7125-update.

## Section 3

In which cases can the Exporter deviate from the SHOULD in `SHOULD use reduced-size encoding` ?

# NITS

## Section 3

Suggest to either use actions (on receiving) or roles(i.e., Exporter) in all clauses in `this Information Element MUST be exported with a value of zero and MUST be ignored by the Collector`

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

IANA has completed its review of draft-ietf-opsawg-rfc7125-update-05. If any part of this review is inaccurate, please let us know.

IANA understands that, upon approval of this document, there is a single action which we must complete.

In the IPFIX Information Elements registry in the IP Flow Information Export (IPFIX) Entities registry group located at:

https://www.iana.org/assignments/ipfix/

the existing registration for

ElementID: 6
Name: tcpControlBits

is to be replaced entirely by the following new registration:

ElementID: 6
Name: tcpControlBits

Data Type:
unsigned16

Data Type Semantics:
flags

Description:
TCP control bits observed for the packets of this Flow. This information is encoded as a bit field; for each TCP control bit, there is a bit in this set. The bit is set to 1 if any observed packet of this Flow has the corresponding TCP control bit set to 1. The bit is cleared to 0 otherwise.

As per [RFC9293], the assignment of the TCP control bits is managed by IANA from the "TCP Header Flags" registry located at:

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

That registry is authoritative to retrieve the most recent TCP control bits.

As the most significant 4 bits of octets 12 and 13 (counting from zero) of the TCP header [RFC9293] are used to encode the TCP data offset (header length), the corresponding bits in this Information Element MUST be exported with a value of zero and MUST be ignored by the collector. Use the tcpHeaderLength Information Element to encode this value.

All TCP control bits (including those unassigned) MUST be exported as observed in the TCP headers of the packets of this Flow.

If exported as a single octet with reduced-size encoding, this Information Element covers the low-order octet of this field (i.e., bit offset positions 8 to 15) in the TCP Header Flags registry. A collector receiving this Information Element with reduced-size encoding must not assume anything about the content of the four bits with bit offset positions 4 to 7.

Exporting Processes exporting this Information Element on behalf of a Metering Process that is not capable of observing any of the flags with bit offset positions 4 to 7 SHOULD use reduced-size encoding, and only export the least significant 8 bits of this Information Element.

Note that previous revisions of this Information Element's definition specified that that flags with bit offset positions 8 and 9 must be exported as zero, even if observed. Collectors should therefore not assume that a value of zero for these bits in this Information Element indicates the bits were never set in the observed traffic, especially if these bits are zero in every Flow Record sent by a given exporter.

Note also that the TCP Header Flags registry indexes the bit offset from the most-significant bit of octet 12 to the least-significant bit of octet 13 in the TCP header, but the tcpControlBits is encoded as a regular unsigned 16 bit integer.

For example, a tcpControlBits Information Element set to 0x90 is used to report TCP control bits for a segment that has CWR (Congestion Window Reduced) and ACK flag bits set (that is, bit offset positions 8 and 11).

MSB----------------------LSB
0 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5
0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 0

Units:

Range:

References:
[RFC9293][ RFC-to-be ]

Additional Information:
See the assigned TCP control bits in the TCP Header Flags registry located at:

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

Revision:
2

As this document requests a registration in an Expert Review or Specification Required (see RFC 8126) registry, we will initiate the required Expert Review via a separate request. This review must be completed before the document's IANA state can be changed to "IANA OK."

We understand that this is the only action required to be completed upon approval of this document.

NOTE: The action 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 action 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 Sr. Specialist

The following Last Call announcement was sent out (ends 2023-10-26):

From: The IESG
To: IETF-Announce
CC: draft-ietf-opsawg-rfc7125-update@ietf.org, jclarke@cisco.com, opsawg-chairs@ietf.org, opsawg@ietf.org, rwilton@cisco.com
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (An Update to the tcpControlBits IP Flow Information Export (IPFIX) Information Element) to Proposed Standard


The IESG has received a request from the Operations and Management Area
Working Group WG (opsawg) to consider the following document: - 'An Update to
the tcpControlBits IP Flow Information Export (IPFIX)
  Information Element'
  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 2023-10-26. 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


  RFC 7125 revised the tcpControlBits IP Flow Information Export
  (IPFIX) Information Element that was originally defined in RFC 5102
  to reflect changes to the TCP header control bits since RFC 793.
  However, that update is still problematic for interoperability
  because some flag values have subsequently been deprecated.

  This document removes stale information from the IPFIX registry and
  avoids future conflicts with the authoritative TCP Header Flags
  registry.

  This document obsoletes RFC 7125.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-opsawg-rfc7125-update/



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

# Document Shepherd Write-Up for Group Documents

*This version is dated 4 July 2022.*

Thank you for your service as a document shepherd. Among the responsibilities is
answering the questions in this write-up to give helpful context to Last Call
and Internet Engineering Steering Group ([IESG][1]) reviewers, and your
diligence in completing it is appreciated. The full role of the shepherd is
further described in [RFC 4858][2]. You will need the cooperation of the authors
and editors to complete these checks.

Note that some numbered items contain multiple related questions; please be sure
to answer all of them.

## 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?

Within the working group, this document was seen as something good and useful to do with the intent to not rush, but fast-track it through the process.  Working group (and directorate) feedback was supportive.  There was a comment from Paul Aitken (after forwarding to ipfix@) that this document should not be adopted on interoperability reasons (see https://mailarchive.ietf.org/arch/msg/opsawg/cGEQp-JLa7yryD0qjK8cE7y7iJI/).  The authors engaged with him, and it seems that this issue was resolved.  The document was ultimately adopted.

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

The above was the only point of contention as this worked progressed, and it was handled in discussion between the authors and Paul.

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][3] recommends) or elsewhere
  (where)?

This work represents a cleanup of the tcpControlBits as it relates to IPFIX so that operators can interpret flow data more accurately.  Implementations insofar as TCP and IPFIX have existed for a long time.  This document more accurately instructs how to interpret this part of the TCP header data.

## 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 document was reviewed by ipfix@ as part of the adoption call and by the transport and routing area directorates.  Routing called out some nits which were corrected in -03 of the draft.

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.

It has been reviewed by IPFIX experts (Benoit Claise and Paul Aitken being two such people).

7. If the document contains a YANG module, has the final version of the module
  been checked with any of the [recommended validation tools][4] 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][5]?

N/A

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.

N/A (other than IDNITS)

## 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, it is.  I have reviewed the document and had a discussion point with the author, which I consider resolved (see IDNITS below).

10. Several IETF Areas have assembled [lists of common issues that their
    reviewers encounter][6]. For which areas have such issues been identified
    and addressed? For which does this still need to happen in subsequent
    reviews?

Transport and Routing have reviewed.  I do not believe detailed subsequent reviews are required.

11. What type of RFC publication is being requested on the IETF stream ([Best
    Current Practice][12], [Proposed Standard, Internet Standard][13],
    [Informational, Experimental or Historic][14])? Why is this the proper type
    of RFC? Do all Datatracker state attributes correctly reflect this intent?

This is a bis document to RFC7125 and, while that was informational, it (like this document) uses normative language and describes how to interpret the tcpControlBits.  The question of track was raised on the list (https://mailarchive.ietf.org/arch/msg/opsawg/xiNdPUoDVFhNfOCKSDFWEJbwzdA/) and when presented at IETF 115.  Given the normative language and instruction on how to interpret the data, it was deemed Proposed Standard is more appropriate for this document.  That track is properly reflected in Data Tracker.

12. Have reasonable efforts been made to remind all authors of the intellectual
    property rights (IPR) disclosure obligations described in [BCP 79][7]? 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.

A poll was sent to the list.  The named author has replied that there is no IPR.  Paul Aitken and Brian Trammel are listed as named contributors (as the authors of 7125), and an IPR request has been sent to them.

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.

14. Document any remaining I-D nits in this document. Simply running the [idnits
    tool][8] is not enough; please review the ["Content Guidelines" on
    authors.ietf.org][15]. (Also note that the current idnits tool generates
    some incorrect warnings; a rewrite is underway.)
There are a few IDNITS thrown for this document.  All are false positives, but one deserves note.  The TCP-FLAGS reference is normative in this document.  It refers to the IANA registry for TCP Header Flags.  The reason for making this normative is that using this registry as the canonical source will inform operators about any future changes to these flags and how to interpret them (via additional RFC references).

15. Should any informative references be normative or vice-versa? See the [IESG
    Statement on Normative and Informative References][16].

See above.  I do not believe any reference changes are required.

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

N/A

17. Are there any normative downward references (see [RFC 3967][9] and [BCP
    97][10]) that are not already listed in the [DOWNREF registry][17]? If so,
    list them.

No.

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?

No.

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 document is a bis for RFC7125 and will obsolete that document.  Yes, this meta-data is correct 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][11]).

This document asks IANA to update the tcpControlBits part of the IPFIX registry to reflect the text in section 3 of this document (i.e., replacing the 7125 text in there now).

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.

N/A

[1]: https://www.ietf.org/about/groups/iesg/
[2]: https://www.rfc-editor.org/rfc/rfc4858.html
[3]: https://www.rfc-editor.org/rfc/rfc7942.html
[4]: https://trac.ietf.org/trac/ops/wiki/yang-review-tools
[5]: https://www.rfc-editor.org/rfc/rfc8342.html
[6]: https://trac.ietf.org/trac/iesg/wiki/ExpertTopics
[7]: https://www.rfc-editor.org/info/bcp79
[8]: https://www.ietf.org/tools/idnits/
[9]: https://www.rfc-editor.org/rfc/rfc3967.html
[10]: https://www.rfc-editor.org/info/bcp97
[11]: https://www.rfc-editor.org/rfc/rfc8126.html
[12]: https://www.rfc-editor.org/rfc/rfc2026.html#section-5
[13]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.1
[14]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.2
[15]: https://authors.ietf.org/en/content-guidelines-overview
[16]: https://www.ietf.org/about/groups/iesg/statements/normative-informative-references/
[17]: https://datatracker.ietf.org/doc/downref/

# Document Shepherd Write-Up for Group Documents

*This version is dated 4 July 2022.*

Thank you for your service as a document shepherd. Among the responsibilities is
answering the questions in this write-up to give helpful context to Last Call
and Internet Engineering Steering Group ([IESG][1]) reviewers, and your
diligence in completing it is appreciated. The full role of the shepherd is
further described in [RFC 4858][2]. You will need the cooperation of the authors
and editors to complete these checks.

Note that some numbered items contain multiple related questions; please be sure
to answer all of them.

## 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?

Within the working group, this document was seen as something good and useful to do with the intent to not rush, but fast-track it through the process.  Working group (and directorate) feedback was supportive.  There was a comment from Paul Aitken (after forwarding to ipfix@) that this document should not be adopted on interoperability reasons (see https://mailarchive.ietf.org/arch/msg/opsawg/cGEQp-JLa7yryD0qjK8cE7y7iJI/).  The authors engaged with him, and it seems that this issue was resolved.  The document was ultimately adopted.

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

The above was the only point of contention as this worked progressed, and it was handled in discussion between the authors and Paul.

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][3] recommends) or elsewhere
  (where)?

This work represents a cleanup of the tcpControlBits as it relates to IPFIX so that operators can interpret flow data more accurately.  Implementations insofar as TCP and IPFIX have existed for a long time.  This document more accurately instructs how to interpret this part of the TCP header data.

## 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 document was reviewed by ipfix@ as part of the adoption call and by the transport and routing area directorates.  Routing called out some nits which were corrected in -03 of the draft.

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.

It has been reviewed by IPFIX experts (Benoit Claise and Paul Aitken being two such people).

7. If the document contains a YANG module, has the final version of the module
  been checked with any of the [recommended validation tools][4] 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][5]?

N/A

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.

N/A (other than IDNITS)

## 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, it is.  I have reviewed the document and had a discussion point with the author, which I consider resolved (see IDNITS below).

10. Several IETF Areas have assembled [lists of common issues that their
    reviewers encounter][6]. For which areas have such issues been identified
    and addressed? For which does this still need to happen in subsequent
    reviews?

Transport and Routing have reviewed.  I do not believe detailed subsequent reviews are required.

11. What type of RFC publication is being requested on the IETF stream ([Best
    Current Practice][12], [Proposed Standard, Internet Standard][13],
    [Informational, Experimental or Historic][14])? Why is this the proper type
    of RFC? Do all Datatracker state attributes correctly reflect this intent?

This is a bis document to RFC7125 and, while that was informational, it (like this document) uses normative language and describes how to interpret the tcpControlBits.  The question of track was raised on the list (https://mailarchive.ietf.org/arch/msg/opsawg/xiNdPUoDVFhNfOCKSDFWEJbwzdA/) and when presented at IETF 115.  Given the normative language and instruction on how to interpret the data, it was deemed Proposed Standard is more appropriate for this document.  That track is properly reflected in Data Tracker.

12. Have reasonable efforts been made to remind all authors of the intellectual
    property rights (IPR) disclosure obligations described in [BCP 79][7]? 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.

A poll was sent to the list.  The named author has replied that there is no IPR.  Paul Aitken and Brian Trammel are listed as named contributors (as the authors of 7125), and an IPR request has been sent to them.

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.

14. Document any remaining I-D nits in this document. Simply running the [idnits
    tool][8] is not enough; please review the ["Content Guidelines" on
    authors.ietf.org][15]. (Also note that the current idnits tool generates
    some incorrect warnings; a rewrite is underway.)
There are a few IDNITS thrown for this document.  All are false positives, but one deserves note.  The TCP-FLAGS reference is normative in this document.  It refers to the IANA registry for TCP Header Flags.  The reason for making this normative is that using this registry as the canonical source will inform operators about any future changes to these flags and how to interpret them (via additional RFC references).

15. Should any informative references be normative or vice-versa? See the [IESG
    Statement on Normative and Informative References][16].

See above.  I do not believe any reference changes are required.

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

N/A

17. Are there any normative downward references (see [RFC 3967][9] and [BCP
    97][10]) that are not already listed in the [DOWNREF registry][17]? If so,
    list them.

No.

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?

No.

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 document is a bis for RFC7125 and will obsolete that document.  Yes, this meta-data is correct 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][11]).

This document asks IANA to update the tcpControlBits part of the IPFIX registry to reflect the text in section 3 of this document (i.e., replacing the 7125 text in there now).

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.

N/A

[1]: https://www.ietf.org/about/groups/iesg/
[2]: https://www.rfc-editor.org/rfc/rfc4858.html
[3]: https://www.rfc-editor.org/rfc/rfc7942.html
[4]: https://trac.ietf.org/trac/ops/wiki/yang-review-tools
[5]: https://www.rfc-editor.org/rfc/rfc8342.html
[6]: https://trac.ietf.org/trac/iesg/wiki/ExpertTopics
[7]: https://www.rfc-editor.org/info/bcp79
[8]: https://www.ietf.org/tools/idnits/
[9]: https://www.rfc-editor.org/rfc/rfc3967.html
[10]: https://www.rfc-editor.org/info/bcp97
[11]: https://www.rfc-editor.org/rfc/rfc8126.html
[12]: https://www.rfc-editor.org/rfc/rfc2026.html#section-5
[13]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.1
[14]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.2
[15]: https://authors.ietf.org/en/content-guidelines-overview
[16]: https://www.ietf.org/about/groups/iesg/statements/normative-informative-references/
[17]: https://datatracker.ietf.org/doc/downref/