RTP Control Protocol (RTCP) Extended Report (XR) Blocks for Summary Statistics Metrics Reporting
draft-ietf-xrblock-rtcp-xr-summary-stat-11

[Ballot comment]
My DISCUSS points are nicely handled in -09; thanks very much for the work.

The "binary point" change is missing in the definition of Burst Discard Rate -- it got into the other three places.  Gonzalo can put in an RFC Editor note asking to fix this, thus:

In Section 3.2.2, please make the following change:

OLD
  Burst Discard Rate: 16 bits

      The fraction of packets discarded during bursts since the
      beginning of reception, expressed as a fixed point number with the
      binary point at the left edge of the field.

NEW
  Burst Discard Rate: 16 bits

      The fraction of packets discarded during bursts since the
      beginning of reception, expressed as a fixed point number with the
      binary point immediately after the left-most bit.

[Ballot comment]
The text in section 3.1.2 describing the representation of loss rates
and in section 3.2.2 describing the representation of discard rates
now appears to be OK.

I trust the differences between these representations and the 8-bit
representations of similar rates in RFC 3611 will not be problematic
or confusing for implementors.

[Ballot comment]
I love it when everyone else gets the DISCUSSes in that I would have before I have a chance. Less typing for me. Definitely support Robert's DISCUSS. Barry and Ralph's DISCUSS looks spot-on.

[Ballot discuss]
Please keep in mind the agreement with the XRBLOCK regarding RFC 6390. See http://datatracker.ietf.org/doc/draft-ietf-xrblock-rtcp-xr-pdv/ballot/#benoit-claise

When I see the following (to take just one example):

    Burst Loss Rate: 16 bits

          The fraction of packets lost during bursts since the beginning of
          reception, expressed as a fixed point number with the binary point
          at the left edge of the field.  This value is calculated by
          dividing Packets Loss in Bursts by Total Packets expected in
          Bursts, multiplying the result of the division by 7FFF, with the
          maximum value 7FFF, and taking the integer part as follows:

          Packets Loss in Bursts / Total Packets expected in Bursts

          If the measurement is unavailable, the value 0x8000 MUST be
          reported.

... you define new metrics in this document.
Therefore the RFC 6390 template must be applied.

Regards, Benoit

[Ballot comment]

The frame impairment block includes the total number of frames
received. I'm not sure if such information is new in XR blocks
or not, but that does suggest a potential attack that I don't
think is noted in 3611 and that might be worth a mention here.

If a bad actor knows that N seconds into a piece of media the
boss says "fire the chief security officer" and the bad actor
could DoS the video stream between "chief" and "security" then
the recipient(s) might take the wrong action. I guess you can
invent a load of amusing variants of this, but this new XR
block could provide the trigger for launching the DoS since it
says how many frames have been received in total.

It is maybe a little silly as an attack, but could be worth
adding.  I won't object if you choose not to add it. If you do,
and other XR blocks expose similar information then I guess
adding references to those would also be nice.

The secdir review [1] suggests a few nit-fixes too.

  [1] http://www.ietf.org/mail-archive/web/secdir/current/msg03762.html

[Ballot discuss]
Following up on Barry's Discuss, and getting some additional
background from RFC 3611, I understand the "Rates" in sections 3.1 and
3.2 to be fixed-point binary fractions, with as assumed binary point
to the left of the fraction carried in the field.  I have to say I
found the description of the computation a little confusing, as I
didn't understand that it was literally telling me how to compute a
decimal number that, when converted to binary, would yield the correct
bit pattern in the field.

However, there is a precedent in RFC 3611 for this descriptive text,
so it makes sense to use the same style in this document.  But, I
don't think the computation still quite yields the right result - why
multiply by 0x7FF rather than 0x10000 (the equivalent of 0x100 as used
in RFC 3611 for an 8-bit field)?

Here's my suggestion, based on Barry's text and using RFC 3611 as a
template:

NEW
      The fraction of packets lost during bursts since the beginning of
      reception, expressed as a fixed point number with the binary point
      at the left edge of the field.  This value is calculated by
      dividing Packets Lost in Bursts by Total Packets Expected in
      Bursts, multiplying the result of the division by 65536,
      limiting the maximum value to 65535 (to avoid overflow)
      and keeping only the integer part.  This field MUST be populated
      and MUST be set to zero if no packets have been received.
END

[Ballot discuss]
The ABNF in section 5.1 needs a minor tweak.

You have double-quote space stuff space double-quote on all three lines that you are adding to xr-format.
You want double-quote stuff double-quote. That is "burst-gap-loss-stat", not " bust-bap-loss-stat ".

The shepherd's writeup indicates N/A for formal language checks?

I'm also not seeing evidence of an SDP directorate review (this is, admittedly a trivial extension to SDP, but that review would have caught this bug).

[Ballot comment]

These spaces-inside-the-quotes also appear in the IANA considerations in section 6.2, but IANA appears to have interpreted the instructions correctly. Consider making 6.2 clearer for future readers, though, to avoid the possibility of misinterpretation.

[Ballot discuss]
This is a fine document, which I'll be happy to see approved.  I'm confused, though, by the definitions of four items, and I worry that it might result in incorrect implementations.

-- Sections 3.1.2 and 3.2.2 --

This comment applies to Burst Loss Rate, Gap Loss Rate, Burst Discard Rate, and Gap Discard Rate.  I'm using the first as an example.

  Burst Loss Rate: 16 bits
      The fraction of packets lost during bursts since the beginning of
      reception, expressed as a fixed point number with the binary point
      at the left edge of the field.  This value is calculated by
      dividing Packets Loss in Bursts by Total Packets expected in
      Bursts, multiplying the result of the division by 7FFF, with the
      maximum value 7FFF, and taking the integer part as follows:

      Packets Loss in Bursts / Total Packets expected in Bursts

I scratched my head over the "and taking the integer part as follows" bit followed by the formula, which appeared to go together and be separate from the rest.  I also didn't understand the formula, because it lacks the multiplier.  And then I think it finally dawned on me what you mean.

Shortening a little here (and assuming that "packets loss" should be "packets lost"), I think you mean for the formula to be
>>  integer-part( (PLB / TPEB) * 32767 )  <<

So, if the total packets expected in bursts (TPEB) is 2,591, and the packets lost in bursts (PLB) is 39, then the Burst Loss Rate value should be 493, or 0x01ED.  Do I have that right?

Assuming I understand correctly, I think a little change would have helped my confusion.  Would you mind doing these four items this way (again, using this one as an example)?:

NEW
      The fraction of packets lost during bursts since the beginning of
      reception, expressed as a fixed point number with the binary point
      at the left edge of the field.  This value is calculated by
      dividing Packets Lost in Bursts by Total Packets Expected in
      Bursts, multiplying the result of the division by 32767 (0x7FFF),
      and keeping only the integer part.  The maximum value is thus
      7FFF.  Representing this as a formula:

      integer-part( (Packets Lost in Bursts / Total Packets Expected in
                    Bursts) * 0x7FFF )
END

Do you see where I was confused before?  Does a change like this work for you?

I'll also note that the "binary point" (I presume this is a binary variant of "decimal point") is not actually at the left edge of the field.  For one thing, the left-most bit is always 0 for any valid value, so the point is at least one bit to the right of that.  For another, a value of "1" (total loss) is represented not by "1.000 0000 0000 0000", but by "0.111 1111 1111 1111".  I don't know how to describe that in terms of the binary point, but I don't think saying that the binary point is at the left edge works.  But if the rest of the description is clear about how to compute the value, I think you can just remove that bit.

(I actually don't understand why you don't multiply by 32768 (0x1000), and use 0xFFFF as the unknown value, because that does put the binary point in a sensible place, and has total loss represented as "1.000 0000 0000 0000".  I see that you do use 0xFFFF as the unknown value for some of the other fields (such as Burst Duration Mean and Burst Duration Variance).  Why not be consistent?)

[Ballot comment]
Here are two very minor and non-blocking points that I'd like you to please consider as well.

-- Sections 3.1.2 and 3.2.2 --

  Reserved: 6 bits
      This field is reserved for future definition.  In the absence of
      such a definition, the bits in this field MUST be set to zero and
      SHOULD be ignored by the receiver (See RFC6709 section 4.2).

But RFC 6079, Section 4.2, says, "Must Be Zero on transmission, Must Be Ignored on reception," not "SHOULD".  Do you really want "SHOULD" here?  If so, why cite 6709 this way?

(Might it also make sense to label these "Reserved: 6 bits (MBZ)", to highlight the connection to what 6709 says?)

-- Section 4.1.2 --

You punctuate "full_lost_frames" inconsistently, using 4 different versions in the same paragraph:
1. full_lost_frames
2. full_lost-frames
3. full lost_ frames
4. full lost frames

There's a similar inconsistency in partial_lost_frames, though it's not quite as bad.  I think the RFC Editor will ask about this, but it will probably be best to fix it now, to avoid AUTH48 delays while you sort it out.

Updated Document Writeup:

(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 - similar to all the other XRBLOCK documents. Header
says ' Intended status: 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

This document defines three RTP Control Protocol (RTCP) Extended
Report (XR) Blocks that allow the reporting of loss, duplication and
discard summary statistics metrics in a range of RTP applications.

Working Group Summary

The WG path of this document was reasonably short and efficient.
Many technical comments were made during the reviews and all were
resolved with consensus.

Document Quality

At least one vendor has implemented this draft. It is expected that with
the approval of this document the number of implementations will increase.

Personnel

Dan Romascanu is the Document Shepherd. Gonzalo Camarillo
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.

I have performed a detailed review of the document and I consider it
ready.

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

No.

(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.

Al Morton performed the PM-DIR review according to RFC 6390. A number of
comments he made led to clarifications included in version 08 of the
document.

(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. Glen Zorn stated that he considers any I-D submission as an
implicit confirmation of the IP terms and conditions, as per BCP 79
section 3.2.1 (see Glen's message at
http://www.ietf.org/mail-archive/web/xrblock/current/msg01109.html)


(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 have been submitted directly on
draft-ietf-xrblock-rtcp-xr-summary-stat or its predecessors.

(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 number of active participants in the Working Group is not very high
(around ten). Among the active participants there seems to be solid
consensus in support of this 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.)

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 excepting the fact that RFC6709 is mentioned in a couple of
places without being put inside brackets (should be [RFC6709]) and a few
references are made on documents that have issued more recent versions
since the publication of the I-D. I hope that the RFC Editor can easily
fix these.


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

See (5)

(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?

N/A

(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).

The document requires from IANA allocations of values in existing
registries which are clearly defined.

(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.

N/A

(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.

N/A

IANA has reviewed draft-ietf-xrblock-rtcp-xr-summary-stat-06 and has the following comments:

We understand that, upon approval of this document, there are two actions which we must complete.

First, in the RTCP XR Block Type subregistry of the RTP Control Protocol Extended Reports (RTCP XR) Block Type Registry located at:

http://www.iana.org/assignments/rtcp-xr-block-types/rtcp-xr-block-types.xml

three new block types will be registered as follows:

BT: [ TBD-at-registration ]
Name: Burst/Gap Loss Summary Statistics Block
Reference: [ RFC-to-be ]

BT: [ TBD-at-registration ]
Name: Burst/Gap Discard Summary Statistics Block
Reference: [ RFC-to-be ]

BT: [ TBD-at-registration ]
Name: Frame Impairment Statistics Summary
Reference: [ RFC-to-be ]

Second, in the RTCP XR SDP Parameters subregistry of the RTP Control Protocol Extended Reports (RTCP XR) Session Description Protocol (SDP) Parameters Registry located at:

http://www.iana.org/assignments/rtcp-xr-sdp-parameters/rtcp-xr-sdp-parameters.xml

three new SDP parameters will be registered as follows:

Parameter: burst-gap-loss-stat
Reference: [ RFC-to-be ]

Parameter: burst-gap-discard-stat
Reference: [ RFC-to-be ]

Parameter: frame-impairment-stat
Reference: [ RFC-to-be ]

We understand that these two actions are the only ones required 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.

The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Subject: Last Call:  (RTP Control Protocol (RTCP) Extended Report (XR) Blocks for Summary Statistics Metrics Reporting) to Proposed Standard


The IESG has received a request from the Metric Blocks for use with
RTCP's Extended Report Framework WG (xrblock) to consider the following
document:
- 'RTP Control Protocol (RTCP) Extended Report (XR) Blocks for Summary
  Statistics Metrics Reporting'
  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 2013-02-01. 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 defines three RTP Control Protocol (RTCP) Extended
  Report (XR) Blocks that allow the reporting of loss, duplication and
  discard summary statistics metrics in a range of RTP applications.




The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-xrblock-rtcp-xr-summary-stat/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-xrblock-rtcp-xr-summary-stat/ballot/


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

(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 - similar to all the other XRBLOCK documents. Header says ' Intended status: 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

This document defines three RTP Control Protocol (RTCP) Extended
Report (XR) Blocks that allow the reporting of loss, duplication and
discard summary statistics metrics in a range of RTP applications.

Working Group Summary

The WG path of this document was reasonably short and efficient.
Many technical comments were made during the reviews and all were
resolved with consensus.

Document Quality

At least one vendor has implemented this draft. It is expected that with
the approval of this document the number of implementations will increase.

Personnel

Dan Romascanu is the Document Shepherd. Gonzalo Camarillo
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.

I have performed a detailed review of the document and I consider it
ready.

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

No.

(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.

This I-D deals with Transport and Application layers metrics.
Although several PM-DIR members participate in the WG, a formal RFC 6390
review could be useful.

(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.

(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 have been submitted directly on draft-ietf-xrblock-rtcp-xr-summary-stat-06 or its predecessors.

(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 number of active participants in the Working Group is not very high (around ten). Among the active participants there seems to be solid consensus in support of this 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.)

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 excepting the fact that RFC6709 is mentioned in a couple of places without being put inside brackets (should be [RFC6709]) and a few references are made on documents that have issued more recent versions since the publication of the I-D. I hope that the RFC Editor can easily fix these.


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

I would recommend for another reviewer from the performance metrics directorate to do an RFC 6390 review of the I-D.

(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?

N/A

(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).

The document requires from IANA allocations of values in existing registries which are clearly defined.

(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.

N/A

(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.

N/A