RTP Control Protocol (RTCP) Extended Report (XR) Block for Delay Metric Reporting
draft-ietf-xrblock-rtcp-xr-delay-12

[Ballot comment]
Thanks for addressing my comments, copied over here, for historical reasons:

In one of my previous DISCUSS-DISCUSS on xr-block, we settle on:

      - RFC 6390 template is required for new perf metric definition

      - RFC 6390 template is a nice-to-have when we refer to an existing
      perf metric

      Nice-to-have because the performance metric reference doesn't
      always include all the required information about: measurement
      points, measurement timing, use and applications, reporting model,
      etc... but focus only on the "Method of Measurement or
      Calculation"   

It might not be fair to change the requirements on this document, while it left the WG some time ago. So I'm ready to let go without the RFC6390 template (http://tools.ietf.org/html/rfc6390#section-5.4.4)
So I'm not opposed to the publication of this document for THAT reason. Note that I will be stricter with future documents.

However, back to this document. You should do a better job of documenting what is required, both from an implementer point of view, and the performance metrics semantic, for someone who might want to(re)- use the metric.
Feel free to discuss with me if I can be of any help

For example: the measurement period is mentioned multiple times in the metric definitions

Mean Network Round Trip Delay: 32 bits

      The Mean Network Round Trip Delay is the mean value of the RTP-to-
      RTP interface round trip delay over the measurement period,
      expressed in units of 1/65536 seconds. 

However, you don't mention where to find it.
I guess it relates to the measurement interval mentioned in

  This metric block
  relies on the measurement interval in the Measurement Information
  block indicating the span of the report and SHOULD be sent in the
  same compound RTCP packet as the measurement information block.

Assuming that the readers understand that the two different names are related, it doesn't tell where to find this information. Is this in http://datatracker.ietf.org/doc/rfc6776/ ?

For example,

  Min Network Round Trip Delay: 32 bits

      The Min Network Round Trip Delay is the minimum value of the RTP-
      to-RTP interface round trip delay over the measurement period,
      expressed in units of 1/65536 seconds.  This value is typically
      determined using RTCP SR/RR.  It also can be determined using RTCP
      Receiver Reference Time Report Block and DLRR Report Block.

The last two sentences. Why not be a little bit more explicit, telling exactly which fields need to be taken into consideration from RTCP SR/SR and from DLRR report block.

[Ballot discuss]


In one of my previous DISCUSS-DISCUSS on xr-block, we settle on:

      - RFC 6390 template is required for new perf metric definition

      - RFC 6390 template is a nice-to-have when we refer to an existing
      perf metric

      Nice-to-have because the performance metric reference doesn't
      always include all the required information about: measurement
      points, measurement timing, use and applications, reporting model,
      etc... but focus only on the "Method of Measurement or
      Calculation"   

It might not be fair to change the requirements on this document, while it left the WG some time ago. So I'm ready to let go without the RFC6390 template (http://tools.ietf.org/html/rfc6390#section-5.4.4)
So I'm not opposed to the publication of this document for THAT reason. Note that I will be stricter with future documents.

However, back to this document. You should do a better job of documenting what is required, both from an implementer point of view, and the performance metrics semantic, for someone who might want to(re)- use the metric.
Feel free to discuss with me if I can be of any help

For example: the measurement period is mentioned multiple times in the metric definitions

Mean Network Round Trip Delay: 32 bits

      The Mean Network Round Trip Delay is the mean value of the RTP-to-
      RTP interface round trip delay over the measurement period,
      expressed in units of 1/65536 seconds. 

However, you don't mention where to find it.
I guess it relates to the measurement interval mentioned in

  This metric block
  relies on the measurement interval in the Measurement Information
  block indicating the span of the report and SHOULD be sent in the
  same compound RTCP packet as the measurement information block.

Assuming that the readers understand that the two different names are related, it doesn't tell where to find this information. Is this in http://datatracker.ietf.org/doc/rfc6776/ ?

For example,

  Min Network Round Trip Delay: 32 bits

      The Min Network Round Trip Delay is the minimum value of the RTP-
      to-RTP interface round trip delay over the measurement period,
      expressed in units of 1/65536 seconds.  This value is typically
      determined using RTCP SR/RR.  It also can be determined using RTCP
      Receiver Reference Time Report Block and DLRR Report Block.

The last two sentences. Why not be a little bit more explicit, telling exactly which fields need to be taken into consideration from RTCP SR/SR and from DLRR report block.

[Ballot discuss]
s3.2: Note that the reserved bits are:

  These bits are reserved.  They MUST be set to zero by senders and
  SHOULD be ignored by receivers.

Any reason it's not MUST be ignored by receivers like in RFC 3611?  Maybe match what's in RFC 6776 :)

  These bits are reserved.  They MUST be set to zero by senders and
  ignored by receivers.

[Ballot comment]


- 3.2: Is the reference to 3611, section 4.1 correct as a
definition for SSRC?

- Not a comment on this draft, but rfc 3611 says that XR
packets should not be encrypted. Has anyone looked to see if
the information leaked by reporting like this could expose
information about encrypted e.g. VoIP traffic?  For example,
the SSRC will be sent in this report in clear, so one might
wonder if that could help someone attack elsewhere. Since
the xrblock WG are doing a bunch of these, I guess it
migth be worth some thought to see if there are any bad
security effects with all of that.

[Ballot comment]
Nicely written document.  Just one non-blocking comment that you needn't respond to.

-- Section 3.2 --
A very minor point, but I find the double-parenthesised explanation of the Interval Metric Flag to be somewhat awkward.  I will suggest this, but if you don't want to change it that's also fine:

NEW
  This field is used to indicate whether the Delay metrics are
  Sampled, Interval or Cumulative metrics:
 
      I=10: Interval Duration - the reported value applies to the most
        recent measurement interval duration between successive metrics
        reports.

      I=11: Cumulative Duration - the reported value applies to the
        accumulation period characteristic of cumulative measurements.

      I=01: Sampled Value - the reported value is a sampled instantaneous
        value.
END

IANA has reviewed draft-ietf-xrblock-rtcp-xr-delay-10 and has
the following comments:

IANA understands that, upon approval of this document, there are two
IANA actions which must be completed.

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

a new RTCP XR Block Type will be registered as follows:

BT: [ TBD ]
Name: Delay Metrics Block
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

a new RTCP XR SDP parameter will be registered as follows:

Parameter: delay
Reference: [ RFC-to-be ]

IANA notes the following person reference related to both of these new
registrations:

Qin Wu (sunseawq@huawei.com)

IANA understands that these are the only actions 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.

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) Block for Delay metric 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) Block for Delay
  metric 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 2012-10-24. 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 defines an RTP Control Protocol(RTCP) Extended Report
  (XR) Block that allows the reporting of Delay metrics for use in a
  range of Real-time Transport Protocol applications.




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

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


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

** Proto-Writeup *******************

Document shepherd write-up for
draft-ietf-xrblock-rtcp-xr-delay-06

(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?

The document is being requested as a Standards Track RFC.

The document defines one new Extended Report (XR)
Report Block [RFC 3611] and standards track is
appropriate for this document.

Standards Track 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 draft defines a new block type to augment those defined in
[RFC3611] for use in a range of RTP applications. The new block type
supports the reporting of the mean, minimum and maximum values of the
network round-trip delay between RTP interfaces in peer RTP end
systems as measured, for example, using the RTCP method described in
[RFC3550]. It also supports reporting of the component of the round-
trip delay internal to the local RTP system.


Working Group Summary

There were several points of debate within the working group; however,
none were particularly rough and authors and commentators came up
with the text that resolves any issues thus consensus was achieved in
all cases.

One issue that was discussed extensively during WGLC was the precision of
measurement in round trip delay (affecting mean/max/min) as well as permitted
delay of 1 second or more. After bringing in reference from other forum such as
Broadband Forum and ITU, WG agreed that delay of 1 seconds or more was
to be accommodated along with ability to come up with precision of microseconds
(1/65536 seconds) for measuring the delay.

Document Quality

This document has been reviewed by numerous people within
XRBLOCK and through two rounds of WGLCs the document
resolved any outstanding issues.

Personnel

Shida Schubert 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 reviewed the last three iterations of this file, including providing
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All of my comments and that of others provided during WGLC are addressed.

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(13) Have all references within this document been identified as
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(14) Are there normative references to documents that are not ready for
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(15) Are there downward normative references (see RFC 3967)?
If so, list these downward references to support the Area Director in
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Last Call procedure.

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(16) Will publication of this document change the status of any
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