Re: [AVTCORE] [xrblock] Open issue- identity info repetition indraft-ietf-avtcore-monarch

Hi, Colin:
It looks like to me we go back to the history and re-pickup the story of identity block again although I haven't gotten invloved into the historical discussion.
However I do check with section 4.3 of draft-clark-avt-rtcphr-02 and compare it with measurement identity block specified in draft-ietf-avt-rtcp
-xr-meas-identity. 
I think identity block has already considered the way on how to correlate RTP-layer identity information with other identity data. If you look at the format
of identity block, you will see identity block defines the sub-identifier field to carry an additional identifier which can be useful in the context of a specific application, e.g.,
IMS Charging Identity,SIP Call-ID, all these additional identity can be included in the identity block. Using this application specific identity information, 
you can easily correlate RTP-layer identity information with other identity data.
I think the only problem with measurement identity block is which kind of information should be included, which kind of information should not be included.
Therefore it will be good to have a template for measurement identity block or any other new RTCP XR block.

Regards!
-Qin
  ----- Original Message ----- 
  From: Colin Perkins 
  To: Qin Wu 
  Cc: AVT WG ; xrblock@ietf.org 
  Sent: Monday, May 16, 2011 6:37 PM
  Subject: Re: [xrblock] [AVTCORE] Open issue- identity info repetition indraft-ietf-avtcore-monarch

  Qin,

  To my mind, the most important part of the identity block was the correlation tag used to relate RTCP statistics to non-RTCP measurements (draft-clark-avt-rtcphr-02 had something along these lines, although more structured than needed). The tools to save space in RTCP XR packets by removing duplicate identity information when stacking reports are less compelling. Given this, I don't see much value in Section 5.2 of draft-ietf-avtcore-monarch as currently written, and would prefer to see the draft focus on ways to correlate RTP-layer identify information with other identify data.

  I'd be interested to hear other opinions though.

  Colin

  On 10 May 2011, at 03:22, Qin Wu wrote:
    Just make correction. My colleague reminds me that the example figure 2  does not conflict with report block format defined in draft-ietf-avt-rtcp-xr-meas-identity-02.
    Since the detailed measurement identity information following the field SSRC of stream source in the figure 2 is omitted.
    However as I mentioned, it is not clear how much information is included in identity block until identity block is clearly defined in XRBlock WG.
    That is why I propose to remove figure 2 and related text from this document.

    Regards!
    -Qin
    ----- Original Message -----
      From: Qin Wu
      To: avt@ietf.org ; xrblock@ietf.org
      Cc: magnus.westerlund@ericsson.com
      Sent: Monday, May 09, 2011 4:08 PM
      Subject: [AVTCORE] Open issue- identity info repetition indraft-ietf-avtcore-monarch

      In the last IETF meeting, there was discussion on identity info repetition or dupplication. However it
       was not clear whether new packet type for identity block is needed. Here is some clarification and
      prososal from my point of view.

      In the example figure 2 of section 5.2 in drat-ietf-avtcore-monarch, it is assumed there is an RTCP
       XR packet containing four metrics blocks, reporting on streams from two source.
      each source is associated with two meric block.

      In order to reduce overhead to carry duplicated data for all the metric block contained in
      the same RTCP XR packet, it was proposed by draft-ietf-avtcore-monarch that measurement
      identity information should be separated from metric block and form independent block.

      However this proposal save zero octets in figure 2. So the question  is
      whether an identity block is actually needed if identity information
      only contain SSRC of stream souce, or if just stacking
      multiple XR Blocks is acceptable.

      However I re-check with RTCP XR Report Block for Measurement Identity defined in
      draft-ietf-avt-rtcp-xr-meas-identity-02, identity information included is more than
      SSRC of stream source. So it should be useful to define new packet type for identity block.

      However the example figure 2(i.e., only contain SSRC of stream souce) is actually not consistent with report block format defined in
      draft-ietf-avt-rtcp-xr-meas-identity-02(i.e., contain more than SSRC of stream source).

      Also as we know, identity block work has just started from XRBlock WG,
      Therefore  I suggest that the example (Figure 2, and the related discussion) is removed until the identity block is clearly
      defined in XRBLock.

      Any Comments or suggestion?

      Regards!
      -Qin

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  Colin Perkins
  http://csperkins.org/