WebRTC MediaStream Identification in the Session Description Protocol
draft-ietf-mmusic-msid-17

[Ballot comment]

My old discuss text was:

START

I'm not sure that the answer to this question will require any
change to the document but wanted to check...

I wondered about the privacy properties of these (and related)
WebRTC identifiers, esp. if they are being handled at various
different layers. Is there work somewhere in the WebRTC space
that's analysing that? For example, one concern might be that
msid-appdata could end up with some kind of privacy sensitive
value, but there's no guidance here about that and as the
examples use UUIDs it's not clear to me those represent nor what
typical values will be used. (Note: I'm not saying that I
believe this is a problem, I'm just checking if it's been
considered.)

I hope that there's no reason why these can't be very ephemeral
values that don't identify (or help re-identification of) people
or their preferences, locations etc., and I'd imagine there's
little reason to e.g. log them. If that's the case wouldn't it
be useful to add such guidance (somewhere, maybe not here)
to help developers to do the right thing?

END

Alissa suggested:

I wonder if adding a reference to https://www.w3.org/TR/mediacapture-streams/#dom-mediastream-id  or parroting that guidance would help.

And in response to a mail from Harald I then said:

Given that the W3C document has the details, I've cleared
the discuss. I do think it'd be good to at least have a
reference to that as Alissa suggested and perhaps to also
re-iterate a bit of the advice about avoiding fingerprinting
perhaps.

[Ballot discuss]

I'm not sure that the answer to this question will require any
change to the document but wanted to check...

I wondered about the privacy properties of these (and related)
WebRTC identifiers, esp. if they are being handled at various
different layers. Is there work somewhere in the WebRTC space
that's analysing that? For example, one concern might be that
msid-appdata could end up with some kind of privacy sensitive
value, but there's no guidance here about that and as the
examples use UUIDs it's not clear to me those represent nor what
typical values will be used. (Note: I'm not saying that I
believe this is a problem, I'm just checking if it's been
considered.)

I hope that there's no reason why these can't be very ephemeral
values that don't identify (or help re-identification of) people
or their preferences, locations etc., and I'd imagine there's
little reason to e.g. log them. If that's the case wouldn't it
be useful to add such guidance (somewhere, maybe not here)
to help developers to do the right thing?

[Ballot comment]
No sure the following is useful information:

  This document is a work item of the MMUSIC WG, whose discussion list
  is mmusic@ietf.org.

First time I see this in an abstract.

[Ballot comment]
= Section 2 =

OLD
Multiple media descriptions with the same value for msid-id and msid-
  appdata is not permitted.

NEW
Multiple media descriptions with the same combination of msid-id and msid-
  appdata are not permitted.

= Section 3 =

s/and when the corresponding media description is disabled/or when the corresponding media description is disabled/

[Ballot comment]
Susan Hares  performed the opsdir review.

Copied here for completeness as it hasn't been addressed yet.

---

I have reviewed this document as part of the Operational directorate's

ongoing effort to review all IETF documents being processed by the IESG.  These

comments were written with the intent of improving the operational aspects of the

IETF drafts. Comments that are not addressed in last call may be included in AD reviews

during the IESG review.  Document editors and WG chairs should treat these comments

just like any other last call comments.





Status:  Almost ready to go, 2 minor concerns, NIT



General comment:  Document and concept are generally clear.  Thank you for providing a simple solution to this problem. 



Caveat:  My expertise is at lower end of the stack.  I cross referenced all the WebRTC documentation, but I’ve missed how implementations provide feedback that this protocols is up and working.  Therefore, I’ve indicated the operational issues as a set of questions for the authors to consider.



Minor concern:

1)      Error handling: Is it possible that the msid-value, msid-id, and msid-appdata can be inserted, and then received with values that are not valid  (1*64token-char]?

a.        If so, an error sequence is necessary.

b.      If not, it is important to explain why not

Add section to 3.2

2)      Operational  issues:  A few questions for your to consider to provide the link to operational issues.



Normal operational:  How does the person who is utilizing this protocol in WebRTC situation check the status of the protocols?  Is it part of the WebRTC status information that the implementations provide?  If so, is there any common management parameters that you can suggest?  Is this in another document in IETF or W3C?



Error operations:  If you can have errors, how does the person who utilizes this protocol in WebRTC  find out the error rate.  Again, is it part of the WebRTC status information on errors?  Is it in another document W3C? 





Editorial NITS:

Page 7, section 3.1



Paragraph 2:  double “,” in the section highlighted makes this sentence’s meaning unclear.

Are these two sub-thoughts? If not two sub-thoughts, then perhaps the /new/ suggested text.



  When MSID is used, the only time this can happen is when, at a time

  subsequent to the initial negotiation, a negotiation is performed

  where the answerer adds a MediaStreamTrack to an already established

  connection and starts sending data before the answer is received by

  the offerer.  For initial negotiation, packets won't flow until the

  ICE candidates and fingerprints have been exchanged, so this is not

  an issue.



/new suggested/

When MSID is used, the only time this can happen is at a time

  subsequent to the initial negotiation,

/



Paragraph 3



Pagination makes the following text difficult.  Repagination in /new/ may help.  Or it may highlight where I was confused by your document.



/old/

The recipient of those packets will perform the following steps:



  o  When RTP packets are initially received, it will create an

      appropriate MediaStreamTrack based on the type of the media

      (carried in PayloadType), and use the MID RTP header extension

      [I-D.ietf-mmusic-sdp-bundle-negotiation] (if present) to associate

      the RTP packets with a specific media section.  If the connection

      is not in the RTCSignalingState "stable", it will wait at this

      point.



  o  When the connection is in the RTCSignalingState "stable", it will

      look at the relevant media section to find the msid attribute.



  o  If there is an msid attribute, it will use that attribute to

      populate the "id" field of the MediaStreamTrack and associated

      MediaStreams, as described above.



  o  If there is no msid attribute, the identifier of the

      MediaStreamTrack will be set to a randomly generated string, and

      it will be signalled as being part of a MediaStream with the

      WebIDL "label" attribute set to "Non-WebRTC stream".



  o  After deciding on the "id" field to be applied to the

      MediaStreamTrack, the track will be signalled to the user.

/



/new/

The recipient of those packets will perform the following steps:



  o  When RTP packets are initially received, it will create an

      appropriate MediaStreamTrack based on the type of the media

      (carried in PayloadType), and use the MID RTP header extension

      [I-D.ietf-mmusic-sdp-bundle-negotiation] (if present) to associate

      the RTP packets with a specific media section. 

-    If the connection is not in the RTCSignalingState "stable", it will wait at this point.

-    When the connection is in the RTCSignalingState "stable", it will look at the relevant media section to find the msid attribute.



·        Looking a Media section:

o    If there is an msid attribute, it will use that attribute to populate the "id" field of the MediaStreamTrack and associated MediaStreams, as described above.

o    If there is no msid attribute, the identifier of the MediaStreamTrack will be set to a randomly generated string, and it will be signalled as being part of a MediaStream with the  WebIDL "label" attribute set to "Non-WebRTC stream".



  o  After deciding on the "id" field to be applied to the

      MediaStreamTrack, the track will be signalled to the user.

/


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[Ballot comment]
I made some editorial comments in my AD evaluation[1] that have not yet been addressed due to an email misconnect. There are no showstoppers there, so I'd like to move this along in parallel.

[1] https://mailarchive.ietf.org/arch/msg/mmusic/KejxusGmZxF6IcEyKmlftpQqosw

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

IANA has completed its review of draft-ietf-mmusic-msid-13.txt. 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 IANA must complete.

In the att-field (media level only) subregistry of the Session Description Protocol (SDP) Parameters registry located at:

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

a single new attribute is to be registered as follows:

Type: att-field (media level only)
SDP Name: msid
Reference: [ RFC-to-be ]

As this document requests registrations in an Expert Review or Specification Required (see RFC 5226) registry, we will initiate the required Expert Review via a separate request. Expert review will need to be completed before your document can be approved for publication as an RFC.

IANA understands that this is the only action 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 Specialist
ICANN

The following Last Call announcement was sent out:

From: The IESG
To: "IETF-Announce"
CC: fandreas@cisco.com, ben@nostrum.com, draft-ietf-mmusic-msid@ietf.org, mmusic@ietf.org, mmusic-chairs@ietf.org
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (WebRTC MediaStream Identification in the Session Description Protocol) to Proposed Standard


The IESG has received a request from the Multiparty Multimedia Session
Control WG (mmusic) to consider the following document:
- 'WebRTC MediaStream Identification in the Session Description Protocol'
  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 2016-05-24. 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 document specifies a Session Description Protocol (SDP) Grouping
  mechanism for RTP media streams that can be used to specify relations
  between media streams.

  This mechanism is used to signal the association between the SDP
  concept of "media description" and the WebRTC concept of
  "MediaStream" / "MediaStreamTrack" using SDP signaling.

  This document is a work item of the MMUSIC WG, whose discussion list
  is mmusic@ietf.org.





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

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


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

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. The title page has an intended status of "Standards Track".


(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.

This document specifies a Session Description Protocol (SDP) Grouping mechanism for RTP media streams that can be used to specify relations between media streams.

This mechanism is used to signal the association between the SDP concept of "media description" and the WebRTC concept of "MediaStream" / "MediaStreamTrack" using SDP signaling.

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 has undergone a number of revisions. Originally, it was believed the mechansim was more generally applicable than WebRTC. As the work progressed, the general applicability became increasingly unclear and a resulting reduction in scope and significant simplication resulted. The WG is fully supportive of this.

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?

Chrome implements an earlier version of the specification and is committed to implementing the specified version at a later stage.

There are no special reviewers or other expert reviews of the document.


Personnel

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

Flemming Andreasen is the document shepherd and Ben Campbell is the responsible 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.

As the document shepherd, I have reviewed multiple versions of the document, including the current one. The document has been reviewed at a technical level as well as the usual nits checks, etc. 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?

Different versions of the document has seen reviews by a decent number of people, which ultimately resulted in the simplified document we currently have. This version of the document has been reviewed by a couple of people. The reviews have been fairly detailed, but more reviewers would obviously have been desirable.


(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.

Not applicable

(6) Describe any specific concerns or issues that the Document Shepherd
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There are no such concerns or issues.

(7) Has each author confirmed that any and all appropriate IPR
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and BCP 79 have already been filed. If not, explain why.

The 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
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There are no IPR disclosures for this document.

(9) How solid is the WG consensus behind this document? Does it
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being silent, or does the WG as a whole understand and agree with it? 

The document has seen solid discussion and review through its lifetime in the WG and as such there is good WG support and consensus behind it.

(10) Has anyone threatened an appeal or otherwise indicated extreme
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Not applicable.

(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.

There are a few warnings about I-D references that are not up-to-date - they can simply be updated during the publication process.

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

No such reviews are required. The document merely defines an extension to SDP.
(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 two references to draft documents:
1) draft-ietf-mmusic-sdp-mux-attributes has been submitted to the IESG for publication
2) draft-ietf-rtcweb-jsep is being worked on by RTCWeb. The RTCWeb chairs do not have an estimated publication request date for this document. 

(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.

Not applicable.

(16) Will publication of this document change the status of any
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in the abstract, and discussed in the introduction? If the RFCs are not
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No change to existing RFCs

(17) Describe the Document Shepherd's review of the IANA considerations
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allocations procedures for future registrations are defined, and a
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I have reviewed the IANA considerations, which register the SDP extension in accordance with the requirements of RFC 4566.

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The document contains a few lines of ABNF which have been verified with Bill Fenner's ABNF parser.