Session Description Protocol (SDP) Offer/Answer Clarifications for RTP/RTCP Multiplexing
draft-ietf-avtcore-5761-update-06

[Ballot comment]
Thanks for doing this work, and for your response to Alissa's comment on answer/answerer.

I did have one question - I wonder if the title

                RFC 5761 SDP Offer/Answer Clarifications

might be clearer for readers who don't have RFC numbers memorized, if it was something like

                a=rtcp-mux SDP Offer/Answer Clarifications

[Ballot comment]
"If the answerer includes an "a=rtcp-mux" attribute in the answer, the
  offerer and answerer MUST multiplex RTP and RTCP packets on a single
  port.

  If the answer does not contain an "a=rtcp-mux" attribute, the offerer
  and answerer MUST NOT multiplex RTP and RTCP packets on a single port."

The first of these says "the answerer" and the second says "the answer." This is also how the text appears in 5761, but the difference between them caught my eye here because of the other changes being made. Is the intended meaning different between "the answerer" and the "the answer"? That is, is the implication that if the answerer include a=rtcp-mux but that somehow gets modified such that when the answer arrives at the offerer, it no longer contains a=rtcp-mux, that neither side is supposed to multiplex? This made a little more sense to me in 5761 because it was only about what the offerer should do, but now it is about what both parties should do, so I think it would help to clarify whether these two statements are both about what the answerer puts in the answer.

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

IANA has reviewed draft-ietf-avtcore-5761-update-01.txt, which is currently in Last Call, and has the following comments:

We understand that this document doesn't require any IANA actions.

While it's often helpful for a document's IANA Considerations section to remain in place upon publication even if there are no actions, if the authors strongly prefer to remove it, IANA does not object.

If this assessment is not accurate, please respond as soon as possible.

Thank you,

Sabrina Tanamal
IANA Specialist
ICANN

The following Last Call announcement was sent out:

From: The IESG
To: "IETF-Announce"
CC: avtcore-chairs@ietf.org, ben@nostrum.com, ron.even.tlv@gmail.com, avt@ietf.org, draft-ietf-avtcore-5761-update@ietf.org, "Roni Even"
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (Updates to RFC 5761) to Proposed Standard


The IESG has received a request from the Audio/Video Transport Core
Maintenance WG (avtcore) to consider the following document:
- 'Updates to RFC 5761'
  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 2016-09-22. 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 updates RFC 5761 by clarifying the SDP offer/answer
  negotiation of RTP and RTCP multiplexing.  It makes it clear that an
  answerer can only include an "a=rtcp-mux" attribute in an SDP answer
  if the associated SDP offer contained the attribute.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-avtcore-5761-update/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-avtcore-5761-update/ballot/


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

This is my AD Evaluation of draft-ietf-avtcore-5761-update-01.

I think this is ready for IETF last call. I have a process and an editorial comment comments that can be considered along with other last call feedback.
----------------
Process:

- This contains a fair amount text from 5761, which contains the pre-RFC5378 disclaimer. Does this draft need the disclaimer? (I hope the answer is no, but did anyone check with the 5761 authors? They are usually easy to find.)

Editorial:

- Am I correct that the entirety of the change in section 3.1 is in paragraph 5? If so, is it necessary to include quite so much text? It makes the changes sort of hard to find. (It seems like section 1 could almost stand on it's own :-) )

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?
This document will be a standard track RFC, the document updates RFC5761 which is a standard track RFC. The type is indicated on the title page

(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:
This document updates RFC 5761 by clarifying the SDP offer/answer  negotiation of RTP and RTCP multiplexing.  It makes it clear that an  answerer can only include an "a=rtcp-mux" attribute in an SDP answer  if the associated SDP offer contained the attribute.

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?
The document was discussed in the meetings,  and on the mailing list. The open issues were addressed and there are no open issues, there was consensus on the content of the document.

Document Quality:
Are there existing implementations of the protocol? Have a significant number of vendors indicated their plan to implement the specification? Are there any reviewers that merit special mention as having done a thorough review, e.g., one that resulted in important changes or a conclusion that the document had no substantive issues? If there was a MIB Doctor, 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?
The document clarifies some text in RFC5761 based also on implementation experience.
Personnel:
Who is the Document Shepherd? Who is the Responsible Area Director?
Roni Even is the Document Shepherd.
The responsible AD is Ben Campbell.
(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.
The document shepherd reviewed the document in previous and current versions and found it ready for publication.

(4) Does the document Shepherd have any concerns about the depth or breadth of the reviews that have been performed?
The document had good reviews before and during the WGLC.  The comments during the WGLC were addressed.

(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.
None.

(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 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?
Yes. The authors confirmed.

(8) Has an IPR disclosure been filed that references this document? If so, summarize any WG discussion and conclusion regarding the IPR disclosures.
There are none.
(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 WG understand the document and agree with it.


(10) Has anyone threatened an appeal or otherwise indicated extreme discontent? If so, please summarise the areas of conflict in separate email messages to the Responsible Area Director. (It should be in a separate email because this questionnaire is publicly available.)
No

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

No issues
(12) Describe how the document meets any required formal review criteria, such as the MIB Doctor, media type, and URI type reviews.
None are needed
(13) Have all references within this document been identified as either normative or informative?
There are only normative references.
(14) Are there normative references to documents that are not ready for advancement or are otherwise in an unclear state? If such normative references exist, what is the plan for their completion?
No
(15) Are there downward normative references references (see RFC 3967)? If so, list these downward references to support the Area Director in the Last Call procedure.
There are none
(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.
This document updates RFC5761 and it is mentioned in the title page, in the abstract and the introduction sections.
(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).
No IANA considerations

(18) List any new IANA registries that require Expert Review for future allocations. Provide any public guidance that the IESG would find useful in selecting the IANA Experts for these new registries.
No  new IANA registries.
(19) Describe reviews and automated checks performed by the Document Shepherd to validate sections of the document written in a formal language, such as XML code, BNF rules, MIB definitions, etc.
None were needed