Subject: [AVT] draft-ietf-avt-rtcp-report-extns-04.txt

From: Timur Friedman <[email-masked]>
Date: Thu, 17 Apr 2003 05:01:48 +0200

AVT colleagues,

We have just submitted version 4 of the RTP Control Protocol Extended Reports 
(RTCP XR) draft to [email-masked] (also attached here).  At this 
point, as discussed in San Francisco, we hope to proceed to working group 
last call.

Below is a list of changes from version 3.  At the following URL is a PDF 
letter-format version of the draft:

http://www-rp.lip6.fr/site_rp/_publications/378-draft-ietf-avt-rtcp-report-extns-04.pdf

Regards,

Timur Friedman

List of changes:

* Addition of an applicability statement section.

* Addition of an SDP signalling section.

* Fixed a major item that was overlooked: the definition of the "SSRC
  of source" field was missing from the blocks that used this field.
  Also, the field was entirely missing from the VoIP Metrics Report
  Block, which ordinarily should use it.  The length of the VoIP
  Metrics Report Block was adjusted accordingly.

* Clarified the different roles performed by the report blocks that
  were known as the Timestamp Report Block and Receiver Timestamp
  Report Block.  The names were too similar, and did not reflect the
  completely different roles played by the blocks.  The blocks have
  been renamed the Packet Receipt Times Report Block and the Receiver
  Reference Time Report Block, respectively.  Some explanatory text
  has been added, and in particular the RTP timestamp fields have been
  renamed Receipt time of packet, and their correspondence with RTP
  data packet timestamps discussed.

* Reorganized the discussion of the block types to fall into three
  categories: detailed packet-by-packet reports, reference time
  reports, and statistical reports.  To accomodate this
  categorization, the Statistics Summary Report Block was moved to
  accompany the VoIP Metrics Report Block.  As the description of the
  Statistics Summary Report Block now follows that of the Packet
  Receipt Times Report Block and the Receiver Reference Time Report
  Block, these three have had their block type numbers changed so as
  to remain consecutive in the document.

* Generalized the TTL reporting in the Statistics Summary Report Block
  to cover IPv6 Hop Limit values as well.  This necessitated the
  introduction of a two bit flag, which is 0 if no values are
  reported, 1 if IPv4 TTL values are reported, and 2 if IPv6 Hop Limit
  values are reported.  A flag value of 3 is undefined and disallowed.

* Additional explanatory text has been provided in the Introduction,
  and to introduce the XR packet format.

* Renamed the type-specific data field of the block framework to
  "type-specific block contents".  Just to be clear that what might be
  considered metadata, such as SSRC values, can perfectly well go
  here.

* For the VoIP Metrics Report Block, eliminated the following
  language: "An implementation that sends these blocks SHOULD send at
  least one every ten seconds for the duration of the call, SHOULD
  send one whenever a codec type change or other significant change
  occurs, SHOULD send one when significant call quality degradation is
  detected and SHOULD send one upon call termination."  We cannot
  specify RTCP packet sending intervals that do not correspond with
  the underlying RTCP rules.