Session Description Protocol (SDP) Offer/Answer Procedures for Stream Control Transmission Protocol (SCTP) over Datagram Transport Layer Security (DTLS) Transport
draft-ietf-mmusic-sctp-sdp-26

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

The IANA Services Operator has completed its review of draft-ietf-mmusic-sctp-sdp-22.txt. If any part of this review is inaccurate, please let us know.

We have a question about one of the actions requested in the IANA Considerations section of this document.

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

First, in the proto subregistry of the Session Description Protocol Parameters registry located at:

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

two new registrations are to be made as follows:

Type: proto
SDP Name: UDP/DTLS/SCTP
Reference: [ RFC-to-be ]

Type: proto
SDP Name: TCP/DTLS/SCTP
Reference: [ RFC-to-be ]

Second, in the att-field (media level only) subregistry also in the Session Description Parameters registry located at:

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

two new registrations are to be made as follows:

Type: att-field (media level only)
SDP Name: sctp-port
Mux Category: CAUTION
Reference: [ RFC-to-be ]

Type: att-field (media level only)
SDP Name: max-message-size
Mux Category: CAUTION
Reference: [ RFC-to-be ]

Because this registry requires Expert Review [RFC5226] for registration, we've contacted the IESG-designated expert in a separate ticket to request approval. Expert review should be completed before your document can be approved for publication as an RFC.

Third, a new registry is to be created called the association-usage Name registry. The registry is to be maintained via First Come, First Served as defined in RFC 5226.

QUESTION -> Where should this new registry be located? Is it a new registry on the list of all IANA maintained protocol parameter registries or is it a subregistry of an existing registry? If it is a subregistry of an existing registry, in which registry will it be contained?

There is a single, new registration in the registry as follows:

Name: webrtc-datachannel
Reference: [ draft-ietf-rtcweb-data-protocol ], [ RFC-to-be ]

We understand that the first reference will be changed to reflect the RFC number once the draft is approved for publication.

The IANA Services Operator understands that these three actions are the only ones 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 only to confirm what actions will be performed.

Thank you,

Sabrina Tanamal
IANA Services Specialist
PTI

The following Last Call announcement was sent out:

From: The IESG
To: "IETF-Announce"
CC: fandreas@cisco.com, ben@nostrum.com, draft-ietf-mmusic-sctp-sdp@ietf.org, mmusic@ietf.org, mmusic-chairs@ietf.org
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (Session Description Protocol (SDP) Offer/Answer Procedures For Stream Control Transmission Protocol (SCTP) over Datagram Transport Layer Security (DTLS) Transport.) to Proposed Standard


The IESG has received a request from the Multiparty Multimedia Session
Control WG (mmusic) to consider the following document:
- 'Session Description Protocol (SDP) Offer/Answer Procedures For Stream
  Control Transmission Protocol (SCTP) over Datagram Transport Layer
  Security (DTLS) Transport.'
  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
ietf@ietf.org mailing lists by 2017-02-09. 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


  The Stream Control Transmission Protocol (SCTP) is a transport
  protocol used to establish associations between two endpoints.
  draft-ietf-tsvwg-sctp-dtls-encaps-09 specifies how SCTP can be used
  on top of the Datagram Transport Layer Security (DTLS) protocol,
  referred to as SCTP-over-DTLS.

  This specification defines the following new Session Description
  Protocol (SDP) protocol identifiers (proto values):'UDP/DTLS/SCTP'
  and 'TCP/DTLS/SCTP'.  This specification also specifies how to use
  the new proto values with the SDP Offer/Answer mechanism for
  negotiating SCTP-over-DTLS associations.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-mmusic-sctp-sdp/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-mmusic-sctp-sdp/ballot/


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

This is my AD Evaluation of draft-ietf-mmusic-sctp-sdp-21. The draft is mostly in good shape, but I would like to at least discuss the substantive comments prior to IETF last call.

----------------
Substantive Comments

-1, first paragraph: RFC 5572-update is currently in IETF LC. Is there a reason not to reference it instead?

-4.1, last paragraph:
I assume this paragraph refers to fmt values used with UDP/DTLS/SCTP or TCP/DTLS/SCTP, not fmt values in general. It would help to be explicit about that. (Also, it seem like this paragraph belongs in section 4.3).

-4.5: The example is missing the sctp-port attribute.

-5.3: Why is the mux-category SPECIAL rather than CAUTION? IIUC, SPECIAL means you need to refer to the rules in the protocol definition. But the text here basically say that the rules are undefined.

-6.1: What is meant by saying an "endpoint MUST assume that larger ... will be rejected"? Can that be stated in terms of actual procedure (e.g. "endpoint MUST NOT send...larger"?

-6.2, "Purpose" field: Please include the unit here, too.

-9.1, 2nd paragraph: Don't the lower layers need to be established before the upper layers? Won't removal of the TCP connection or DTLS association break an existing SCTP association?

-18.2: Seems like RFC0793 and RFC6544 should be normative references.

Editorial Comments:

-1, 2nd paragraph: Seems like SCTP is also used to transport data :-)

-1, last paragraph: is "strongly RECOMMENDED" intended to be stronger than RECOMMENDED? Assuming you don't mean MUST, please consider dropping the adverb.

-6.1, typo: thevmaximum

-9.1, 2nd paragraph: s/mange/manage

-9.3, last paragraph: What does "impact" mean in context? Change state? (It seems like these actions would likely cause data to be sent at the SCTP layer, which seems like a kind of impact.)

-10.3: Does "identical" mean identical to that from the offer?

-10.3, 8th paragraph: s/"closing establishing"/"closing or establishing"

As required by RFC 4858, this is the current template for the Document
Shepherd Write-Up.

Changes are expected over time. This version is dated 24 February 2012.

(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  - Standards Track is indicated on the title page.

The document standardizes SDP Offer/Answer procedures for SCTP over DTLS and hence Standards Track is appropriate.

(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

  Relevant content can frequently be found in the abstract
  and/or introduction of the document. If not, this may be
  an indication that there are deficiencies in the abstract
  or introduction.

The Stream Control Transmission Protocol (SCTP) is a transport protocol used to establish associations between two endpoints. SCTP can be used on top of the Datagram Transport Layer Security (DTLS) protocol, referred to as SCTP-over-DTLS.

This specification defines the following new Session Description Protocol (SDP) protocol identifiers (proto values): 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP'.  This specification also specifies how to use the new proto values with the SDP Offer/Answer mechanism for negotiating SCTP-over-DTLS associations.


Working Group Summary

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

Nothing in particular to note. The document has seen decent WG participation and no particular “roughness” in terms of consensus.


Document Quality

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

There are existing implementations of earlier versions of the document and those implementations are expected to be updated. The specification is required in order to use SDP for negotiating WebRTC data channels and hence is expected to see significant vendor adoption.

MIB Doctor, etc. review is Not Applicable.

Personnel

  Who is the Document Shepherd? Who is the Responsible Area
  Director?

Flemming Andreasen is the Document Shepherd
Ben Campbell is the Area Director.


(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.

I have reviewed -19 in detail as well as the resulting changes in the -20 and -21 versions. The review includes ID-Nits check as well. The document is ready for publication.

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

No. Several people have both contributed to and reviewed the document.

(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.

N/A

(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 such 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.

Each author has confirmed.


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

No IPR disclosure.

(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? 

The document has solid consensus in the WG with several people having participated in both the development and review of the document.


(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.)

N/A

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

ID nits check yields a few warnings and comments, however none of them are real issues:
- IPv6 address examples are not necessary since IP version differences are immaterial to the purpose of the specification.
- Section references are using square brackets, which triggers a few (false) warnings


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

N/A

(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?

There are 4 such references which plans as follows:

draft-ietf-mmusic-4572-update is ready for Publication Request

draft-ietf-mmusic-dtls-sdp is expected to proceed towards Publication Request within a few months

draft-ietf-tsvwg-sctp-dtls-encaps is with the RFC Editor, where it is in MISSREF state waiting for draft-ietf-tsvwg-sctp-ndata. That particular draft is currently in WGLC and is expected to be with the IESG before the next IETF Meeting (IETF 98, March 26, 2017). 

draft-ietf-mmusic-sdp-mux-attributes is with the RFC Editor where it is in MISSREF state waiting for another MMUSIC document (draft-ietf-mmusic-sdp-bundle-negotiation) that is expected to proceed towards Publication Request within a few months.

The draft is furthermore requesting that its publication waits for draft-ietf-rtcweb-data-protocol, which is currently with the RFC Editor in MISSREF state. That document has references to JSEP (draft-ietf-rtcweb-jsep) and two RTCWeb security documents. The RTCWeb WG chairs aim to get these publication requested before IETF 98, however JSEP may require further discussion at that meeting to resolve an issue.

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

N/A

(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.

N/A

(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 5226).

IANA Considerations have been reviewed per the above, which resulted in some document changes reflected in the latest version of the document. 


(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.

The document defines a new IANA registry with a registration policy of "First Come First Served" and hence no designated expert is required.

(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, etc.

ABNF has been verified with Bill Fenner's ABNF Parser.