ALPN ID Specification for CoAP over DTLS
draft-ietf-core-coap-dtls-alpn-05

Received changes through RFC Editor sync (changed state to RFC, created became rfc relationship between draft-ietf-core-coap-dtls-alpn and RFC 9952, changed IESG state to RFC Published)

[Ballot comment]
I am a bit surprised this is not Standards Track, as it is the output of a WG, and seems to apply ti various other protocol documents that will use it.

[Ballot comment]
Thanks to Joe Salowey for their secdir reviews.

Section 1:  Instead of just referencing DTLS with two RFCs, perhaps say that 'DTLS 1.2 or 1.3' and then add the RFC references.  Do the same for TLS - add the 1.3.

[Ballot comment]
# Andy Newton, ART AD, comments for draft-ietf-core-coap-dtls-alpn-04
CC @anewton1998

* line numbers:
  - https://author-tools.ietf.org/api/idnits?url=https://www.ietf.org/archive/id/draft-ietf-core-coap-dtls-alpn-04.txt&submitcheck=True

* comment syntax:
  - https://github.com/mnot/ietf-comments/blob/main/format.md

* "Handling Ballot Positions":
  - https://ietf.org/about/groups/iesg/statements/handling-ballot-positions/

## No Objection

I echo Barry Lieba's ARTART review: "Simple, straightforward, ready.  No further comment."

[Ballot comment]
Thanks for the work done in short but useful document.

Like Med Boucadair, I wonder about the choice of "co" as I would expect either "c" (the smallest possible to be used in constrained environment) or "coap" like the TLS version as I do not understand why different transports require different ALPN.

[Ballot comment]
Hi Martine, Christian, Thomas, and Matthias,

Thank you for the effort put into this document.

I do fully support a separate ALPN ID for CoAP-over-DTLS.

As already indicated in [1], my initial take was that this is better merged with I-D.ietf-core-dns-over-coap. That approach has the merit to bind it to a case that motivated the registration at the first place. Doing so does not restrict by any means the applicability of the new ALPN ID. That's said, I consider that point "closed" as this point was discussed early in the process and the WG decided to keep the registration separate. Ack!

# Better ID?

Compared to "coap", "co" is ambiguous.

I understand the rationale is to have a short ID. "cod" (for CoAP over DTLS) or simply "cd" would reflect better the intended usage, IMO.

Cheers,
Med

[1] https://mailarchive.ietf.org/arch/msg/core/f4vW-60UyFfnq60zFCYR4QGJeLg/

IESG/Authors/WG Chairs:

IANA has completed its review of draft-ietf-core-coap-dtls-alpn-04. 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 TLS Application-Layer Protocol Negotiation (ALPN) Protocol IDs registry in the Transport Layer Security (TLS) Extensions registry group located at:

https://www.iana.org/assignments/tls-extensiontype-values/

the early registration for:

Protocol: CoAP (over DTLS)
Identification sequence: 0x63 0x6f ("co")

will be made permanent and its reference changed to [RFC7252] and [ RFC-to-be ].

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 2025-06-16):

From: The IESG
To: IETF-Announce
CC: core-chairs@ietf.org, core@ietf.org, draft-ietf-core-coap-dtls-alpn@ietf.org, marco.tiloca@ri.se, mbishop@evequefou.be
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (ALPN ID Specification for CoAP over DTLS) to Informational RFC


The IESG has received a request from the Constrained RESTful Environments WG
(core) to consider the following document: - 'ALPN ID Specification for CoAP
over DTLS'
  as Informational RFC

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 2025-06-16. 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 specifies an Application-Layer Protocol Negotiation
  (ALPN) ID for transport-layer-secured Constrained Application
  Protocol (CoAP) services.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-core-coap-dtls-alpn/



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

# Document Shepherd Writeup for draft-ietf-core-coap-dtls-alpn

Document status: https://datatracker.ietf.org/doc/draft-ietf-core-coap-dtls-alpn/

Document Shepherd: Marco Tiloca

Area Director: Mike Bishop


## Document Summary

This document specifies an Application-Layer Protocol Negotiation (ALPN) ID, as intended for services that use the Constrained Application Protocol (CoAP) and are secured by transport layer security using DTLS.

This is aligned with the ALPN ID for CoAP services secured by TLS, which has already been specified in RFC 8323.


## 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?

  The WG has reached broad agreement and strong consensus on this document.

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

  There has been no controversy during the development of this document.

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)?

  Not applicable, since this is not a protocol document.


### 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 interacts with ALPN and its use in Service Bindings (SVCB) via the DNS for service discovery. Pertinent reviews in this respect have occurred. In particular:

  * Rich Salz as Designated Expert reviewed and approved the registration request for the "CoAP (over DTLS)" entry made by this document for the "TLS Application-Layer Protocol Negotiation (ALPN) Protocol IDs" IANA registry at https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml#alpn-protocol-ids

  * Mohamed Boucadair and Ben Schwartz provided reviews already before the WG adoption of the previous individual submission draft-lenders-core-coap-dtls-svcb, as to the use of the new ALPN ID in SVCB and the overall scope of the document.

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?

  Not applicable.

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?

  The Shepherd fully supports the document and believes it to be ready.

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?

    None of the common issues from the IETF areas has been identified as applicable to this document.

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?

    The intended RFC status is Informational, since the document is about registering an entry in the "TLS Application-Layer Protocol Negotiation (ALPN) Protocol IDs" IANA registry (which has registration procedure "Expert Review"), together with considerations that put such a registration in context.

    All Datatracker state attributes correctly reflect this intent.

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.

    Each author has stated that they do not have direct, personal knowledge of any IPR related to this document. The Shepherd is not aware of any IPR either, and no IPR discussion about this document has occurred in the CoRE WG.

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 is not enough; please review the "Content Guidelines" on authors.ietf.org.

    No I-D nits are left; the few warnings and comments raised by the idnits tool are actually fine.

    In particular, the reference to RFC 6347 (obsoleted by RFC 9147) is intentional. This is in order to explicitly consider also DTLS 1.2, as the secure communication protocol originally selected for CoAP in RFC 7252.

    The document complies with the "Content Guidelines" on authors.ietf.org.

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

    References are listed in the appropriate category.

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

    All the normative references are freely available.

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.

    This document does not include any such normative reference.

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?

    This document does not include any such normative reference.

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.

    No.

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 considerations in Section 4.1 are about the registration request for the "CoAP (over DTLS)" entry in the "TLS Application-Layer Protocol Negotiation (ALPN) Protocol IDs" registry, within the "Transport Layer Security (TLS) Extensions" registry group.

    The registration did occur through the individual submission draft-lenders-core-coap-dtls-svcb that was later replaced by the present WG document. Section 4.1 also provides context information about RFC 7252 not defining the use of ALPN, about which this document takes no action.

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.

    Not applicable.

# Document Shepherd Writeup for draft-ietf-core-coap-dtls-alpn

Document status: https://datatracker.ietf.org/doc/draft-ietf-core-coap-dtls-alpn/

Document Shepherd: Marco Tiloca

Area Director: Mike Bishop


## Document Summary

This document specifies an Application-Layer Protocol Negotiation (ALPN) ID, as intended for services that use the Constrained Application Protocol (CoAP) and are secured by transport layer security using DTLS.

This is aligned with the ALPN ID for CoAP services secured by TLS, which has already been specified in RFC 8323.


## 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?

  The WG has reached broad agreement and strong consensus on this document.

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

  There has been no controversy during the development of this document.

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)?

  Not applicable, since this is not a protocol document.


### 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 interacts with ALPN and its use in Service Bindings (SVCB) via the DNS for service discovery. Pertinent reviews in this respect have occurred. In particular:

  * Rich Salz as Designated Expert reviewed and approved the registration request for the "CoAP (over DTLS)" entry made by this document for the "TLS Application-Layer Protocol Negotiation (ALPN) Protocol IDs" IANA registry at https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml#alpn-protocol-ids

  * Mohamed Boucadair and Ben Schwartz provided reviews already before the WG adoption of the previous individual submission draft-lenders-core-coap-dtls-svcb, as to the use of the new ALPN ID in SVCB and the overall scope of the document.

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?

  Not applicable.

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?

  The Shepherd fully supports the document and believes it to be ready.

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?

    None of the common issues from the IETF areas has been identified as applicable to this document.

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?

    The intended RFC status is Informational, since the document is about registering an entry in the "TLS Application-Layer Protocol Negotiation (ALPN) Protocol IDs" IANA registry (which has registration procedure "Expert Review"), together with considerations that put such a registration in context.

    All Datatracker state attributes correctly reflect this intent.

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.

    Each author has stated that they do not have direct, personal knowledge of any IPR related to this document. The Shepherd is not aware of any IPR either, and no IPR discussion about this document has occurred in the CoRE WG.

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 is not enough; please review the "Content Guidelines" on authors.ietf.org.

    No I-D nits are left; the few warnings and comments raised by the idnits tool are actually fine.

    In particular, the reference to RFC 6347 (obsoleted by RFC 9147) is intentional. This is in order to explicitly consider also DTLS 1.2, as the secure communication protocol originally selected for CoAP in RFC 7252.

    The document complies with the "Content Guidelines" on authors.ietf.org.

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

    References are listed in the appropriate category.

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

    All the normative references are freely available.

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.

    This document does not include any such normative reference.

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?

    This document does not include any such normative reference.

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.

    No.

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 considerations in Section 4.1 are about the registration request for the "CoAP (over DTLS)" entry in the "TLS Application-Layer Protocol Negotiation (ALPN) Protocol IDs" registry, within the "Transport Layer Security (TLS) Extensions" registry group.

    The registration did occur through the individual submission draft-lenders-core-coap-dtls-svcb that was later replaced by the present WG document. Section 4.1 also provides context information about RFC 7252 not defining the use of ALPN, about which this document takes no action.

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.

    Not applicable.