RTP Payload Format for G.711.0
draft-ietf-payload-g7110-06

[Ballot comment]
Thanks for adding text on the output buffer overrun risk and your explanation as to why no reference is needed to RFC6562 (Guidelines for the Use of Variable Bit Rate Audio with Secure RTP).

[Ballot discuss]
Hello, 

Thanks for your work on this draft. The SecDir review turned up a few important considerations that I'd like to discuss.
Here is a link to the review and I have one outstanding question that I don't think was addressed yet - maybe I missed it or maybe there is a quick explanation as to why this doesn't matter.  If it's the latter, please let me know the explanation.

https://www.ietf.org/mail-archive/web/secdir/current/msg05189.html

It seems there should be a reference to RFC 6562 (Guidelines for the Use of Variable Bit
Rate Audio with Secure RTP) in the Security Considerations
section, can that be added or is there a reason to leave it out?
The VBR security problems cited in RFC 6562 seem to apply to this
draft and the mitigation techniques described in the draft don't seem to
properly address those problems. For example, adding statistically variable
padding to very small G.711.0 frames would not prevent recognition of a
prerecorded message if the set of all possible messages is known. If the
authors of this draft have not consulted an expert on the security issues
raised by VBR, they should do so.

Thank you.

[Ballot comment]
I want to thank David Black for an extensive review of this document, as well as the authors for working diligently through some of the points raised. The discussion is still ongoing, but I see Joel has already a Discuss raised to ensure that the resolutions get completed. Thank you. I am interested in the resolutions, but I do not plan to hold another Discuss for the same topic.

[Ballot discuss]
Holding a discuss for the resolution of the genart / opsdir  dicussion.

http://www.ietf.org/mail-archive/web/gen-art/current/msg10824.html

I expect a rev or an rfc editor note, or a line from the participants that this is now copacetic.

thanks

[Ballot comment]
I can't say I truly understand the technology in G.711.0 (let alone G.711), but I am still left to wonder why section 3 is in this document. I would expect any implementer is going to have to read the G.711 specs anyway in order to produce the data, and section 3 just seems to repeat information you could get from there. Maybe there's something in section 3.3.1 which adds something specific to RTP, but otherwise, I don't understand. Can this be deleted? (Nobody ever wants to delete things from documents.)

Throughout: I always find the "we" language jarring. "We" in this case is the WG, and that just comes out sounding bizzarre. Instead of "we note", use "note that". Instead of "In this section we describe", say "This section describes". Etc. Please change this.

3.3: Hiding a MUST inside a figure is a really bad idea. Luckily, the MUST is useless. Change "MUST be" to "is" and you're fine.

3.3.1: Change "MUST be supported" to "are always supported".

Except for the one in section 5.3, you really should change all "MAY"s to "can"s. The one is section 4.2.1 and the one at the end of section 4.2.2 are harmless but useless. The one at the beginning of 4.2.2 is a bit more problematic: As written "MAY be any integer multiple of 5 ms" means that it also MAY be 23 ms (because having it be a multiple of 5 ms is OPTIONAL). If you want this to be a requirement, perhaps you mean, "MUST be any integer multiple of 5 ms", but I think "can" is correct. The one at the end of 4.2.4 cracks me up. Speaking of which:

4.2.4:

  When SDP is used, the number of
  channels is known because the optional parameter is a MUST when there
  is more than one channel negotiated (see Section 5.1).  Additionally,
  when SDP is used the parameter ptime is a RECOMMENDED optional
  parameter.

OK, I have to say, using MUST as a noun would be pretty funny by itself, but also getting in a "RECOMMENDED optional parameter" is just adorable! :-D Do you simply mean the following?:

  When SDP is used, the number of channels is known because the
  channels parameter is always present when there is more than one
  channel negotiated (see Section 5.1).  Additionally, when SDP is used
  the parameter ptime is normally present.
 
I think that's simpler and clearer.

[Ballot discuss]
Hello, 

Thanks for your work on this draft. The SecDir review turned up a few important considerations that I'd like to discuss.
Here is a link to the review (includes nits and grammar that you should look at as well in addition to the points I'll pull out below):
https://www.ietf.org/mail-archive/web/secdir/current/msg05189.html

It seems there should be a reference to RFC 6562 (Guidelines for the Use of Variable Bit
Rate Audio with Secure RTP) in the Security Considerations
section, can that be added or is there a reason to leave it out?
The VBR security problems cited in RFC 6562 seem to apply to this
draft and the mitigation techniques described in the draft don't seem to
properly address those problems. For example, adding statistically variable
padding to very small G.711.0 frames would not prevent recognition of a
prerecorded message if the set of all possible messages is known. If the
authors of this draft have not consulted an expert on the security issues
raised by VBR, they should do so.

In addition to this concern, there may be a buffer overrun
vulnerability in the payload decoding algorithm described in section 4.2.3.
The authors carefully ensure that the input buffer is not overrun but no
similar protections for the output buffer are described. At least, the SecDir reviewer (& I) didn't
see them. A buffer overrun of the output buffer would be a major flaw. If such
a flaw is present, it would be best to correct this now.

Please see their review for nits.

Thanks.

[Ballot discuss]
Hello, 

Thanks for your work on this draft. The SecDir review turned up a few important considerations that I'd like to discuss.
Here is a link to the review (includes nits and grammar that you should look at as well in addition to the points I'll pull out below):
https://www.ietf.org/mail-archive/web/secdir/current/msg05189.html

It seems there should be a reference to RFC 6562 (Guidelines for the Use of Variable Bit
Rate Audio with Secure RTP) in the Security Considerations
section, can that be added or is there a reason to leave it out?
The VBR security problems cited in RFC 6562 seem to apply to this
draft and the mitigation techniques described in the draft don't seem to
properly address those problems. For example, adding statistically variable
padding to very small G.711.0 frames would not prevent recognition of a
prerecorded message if the set of all possible messages is known. If the
authors of this draft have not consulted an expert on the security issues
raised by VBR, they should do so.

In addition to this concern, there may be a buffer overrun
vulnerability in the payload decoding algorithm described in section 4.2.3.
The authors carefully ensure that the input buffer is not overrun but no
similar protections for the output buffer are described. At least, the SecDir reviewer (& I) didn't
see them. A buffer overrun of the output buffer would be a major flaw. If such
a flaw is present (and I believe that it is), the document should not be
allowed to proceed until this flaw is fixed.

Please see there review for nits.

Thanks.

[Ballot comment]
= Section 5 =
"The parameters defined here as a part of the media subtype
  registration for the G.711.0 codec."

s/as/are/ (or is there some other word missing?)

= Section 5.1 =
s/values are "complaw=al" or "complaw=mu" are used/values "complaw=al" or "complaw=mu" are used/

IESG/Authors/WG Chairs:

IANA has reviewed draft-ietf-payload-g7110-03. Please report any inaccuracies and respond to any questions as soon as possible.

IANA's reviewer has the following comments:

IANA understands that, upon approval of this document, there is a single action that requires completion.

In the audio media types registry located at:

https://www.iana.org/assignments/media-types/

IANA will register the following new media type:

Name: G711-0
Template: [ provided in Section 5.1 of [ RFC-to-be ] ]
Reference: [ RFC-to-be ]

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.

The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (RTP Payload Format for G.711.0) to Proposed Standard


The IESG has received a request from the Audio/Video Transport Payloads
WG (payload) to consider the following document:
- 'RTP Payload Format for G.711.0'
  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 2014-10-27. 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 the Real-Time Transport Protocol (RTP)
  payload format for ITU-T Recommendation G.711.0.  ITU-T Rec. G.711.0
  defines a lossless and stateless compression for G.711 packet
  payloads typically used in IP networks.  This document also defines a
  storage mode format for G.711.0 and a media type registration for the
  G.711.0 RTP payload format.




The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-payload-g7110/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-payload-g7110/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?
This document will be a standard track RFC, it specifies and RTP payload format for ITU-T G.711.0. RTP payload format are standard track documents.

(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 document specifies the Real-Time Transport Protocol (RTP) payload format for ITU-T Recommendation G.711.0.  ITU-T Rec. G.711.0 defines a lossless and stateless compression for G.711 packet payloads typically used in IP networks.  This document also defines a storage mode format for G.711.0 and a media type registration for the  G.711.0 RTP payload format.
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 initial individual draft had a section about G.711.0 “in the middle” this was removed before the document became a WG document. There were no other concerns or objections to 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?

There is an existing implementation. The request for a media type review was posted on March 4th, 2014.


Personnel

  Who is the Document Shepherd? Who is the Responsible Area
  Director?
Document Shepherd is Roni Even and the responsible AD is Richard Barnes.

(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 some reviews before and during the WGLC. The WGLC was extended to allow for more comments.

(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. There was also a question on the list to the authors to verify it.

(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 disclosures.

(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.

(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 normative references to ITU-T documents

(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.

No

(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).

The IANA section is in line with 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.
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.
No need.

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?

(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.

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?

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?

Personnel

  Who is the Document Shepherd? Who 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.

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



(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.

(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.

(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.

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

(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? 

(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.)

(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.

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

(13) Have all references within this document been identified as
either normative or informative?

(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?

(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.

(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.


(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).

(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.

(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.