Sending Multiple RTP Streams in a Single RTP Session
draft-ietf-avtcore-rtp-multi-stream-11

[Ballot comment]
Thank you for doing this work.

I have a small number of comments you might consider.

In this text:

      Note: The above is chosen to match the TCP initial window of 4
      packets, not the larger TCP initial windows for which there is an
      ongoing experiment.  The reason for this is a desire to be
      conservative, since an RTP endpoint will also in many cases start
      sending RTP data packets at the same time as these initial RTCP
      packets are sent.
     
Not to be pedantic, but it would be more correct to say "TCP maximum initial window of 4 packets". RFC 3390 describes this in TCP-speak as

  Equivalently, the upper bound for the initial window size is based on
  the MSS, as follows:

      If (MSS <= 1095 bytes)
          then win <= 4 * MSS;
      If (1095 bytes < MSS < 2190 bytes)
          then win <= 4380;
      If (2190 bytes <= MSS)
          then win <= 2 * MSS;

If you end up making changes to this text, providing RFC 3390 as the reference for 4 and RFC 6928 for the experiment would make the reader's job easier.

In this text:

  The above algorithm has been shown in simulations to maintain the
  inter-RTCP packet transmission time distribution for each SSRC, and
  to consume the same amount of bandwidth as non-aggregated RTCP
  packets. 
 
is there a reference you could provide for the simulations?

In this text:

  The finality of sending RTCP BYE, means that endpoints needs to
  consider if the ceasing of transmission of an RTP stream is temporary
  or more permanent.

I don't understand the subtlety of "more permanent" - is this "permanent"?

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

IANA has reviewed draft-ietf-avtcore-rtp-multi-stream-09.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.

The following Last Call announcement was sent out:

From: The IESG
To: "IETF-Announce"
CC: avtcore-chairs@ietf.org, ben@nostrum.com, roni.even@mail01.huawei.com, draft-ietf-avtcore-rtp-multi-stream@ietf.org, avt@ietf.org
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (Sending Multiple Media Streams in a Single RTP Session) to Proposed Standard


The IESG has received a request from the Audio/Video Transport Core
Maintenance WG (avtcore) to consider the following document:
- 'Sending Multiple Media Streams in a Single RTP Session'
  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 2015-11-24. 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 memo expands and clarifies the behaviour of Real-time Transport
  Protocol (RTP) endpoints that use multiple synchronization sources
  (SSRCs).  This occurs, for example, when an endpoint sends multiple
  media streams in a single RTP session.  This memo updates RFC 3550
  with regards to handling multiple SSRCs per endpoint in RTP sessions,
  with a particular focus on RTCP behaviour.  It also updates RFC 4585
  to update and clarify the calculation of the timeout of SSRCs and the
  inclusion of feedback messages.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-avtcore-rtp-multi-stream/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-avtcore-rtp-multi-stream/ballot/


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

Here is my AD evaluation of draft-ietf-avtcore-rtp-multi-stream-09:

Substantive Comments:
=====================

- 3.3, last paragraph: "The endpoint MUST keep its total media sending rate within
  this share."

Does that need to be a 2119 "MUST"? Does it create a new normative requirement, or restate an existing requirement?

- 5: " ... the specification MUST be interpreted as each SSRC counting as a separate participant ..."

Does that really need to be a 2119 MUST? If so, please consider avoiding a word so open to interpretation as "interpreted".

- 5.2, Note: "... based on an TCP initial window of 4 packets, not the larger TCP initial windows..."

I assume this means that you borrowed the window size from tcp, not that this mechanism actually uses or requires tcp, right? “Based on TCP” is a bit confusing.


Editorial Comments:
===================

-3.3, last paragraph:

s/"to be generating" / "to generate"

- 5.3.2, last paragraph:

singular/plural mismatch between "investigations" and "has".

- 6.1, 2nd paragraph:

First sentence seems redundant to the previous paragraph.

- 6.2, 1st paragraph:

s/"...SSRCs are removed ..."/"... SSRCs be removed ..."

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, This memo expands and clarifies the behavior of Real-time Transport  Protocol (RTP) endpoints that use multiple synchronization sources (SSRCs).  It updates RF3550 and RFC4585.The type is indicated in 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 memo expands and clarifies the behavior of Real-time Transport Protocol (RTP) endpoints that use multiple synchronization sources (SSRCs).  This occurs, for example, when an endpoint sends multiple media streams in a single RTP session.  This memo updates RFC 3550 with regards to handling multiple SSRCs per endpoint in RTP sessions,  with a particular focus on RTCP behavior.  It also updates RFC 4585 to update and clarify the calculation of the timeout of SSRCs and the inclusion of feedback messages.

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?

This document is not a protocol, this work was done based on input from RTCWEB WG and vendors will support it.
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 version 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 during its progress and had good enough reviews during the WGLC.

(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.
No need

(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.
No IPR
(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.
No need for formal review
(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?
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 RFC3550 and RFC4585, mentioned in the abstract and the introduction and listed on the title page.
(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 action

(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 IANA action
(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.
No need