Subject: [AVT] Comments on the Global reporting mode of the RTCP-HR

From: "Hideaki YAMADA" <[email-masked]>
Date: Mon, 9 Jul 2007 00:49:42 +0900

Dear Sirs,

As you know, most multimedia speech sessions over IP-based networks use RTP/RTCP. However, the feedback mechanism provided on an end-to-end network basis is insufficient for controlling the service sessions in FMC (Fixed and Mobile Convergence) networks since the fluctuant quality of end-to-end networks depends on that of both IP-based mobile and fixed networks, and it is difficult to separate the quality of individual networks from the observation of overall quality of end-to-end networks. 
I also believe that the RTCP-HR reports provide useful monitoring information and a diagnosis of VoIP performance between the RTP end systems.

I think that the measurement modes involving translators described in this RTCP-HR draft. The translators are able to provide informative reports of packet loss, round trip delay, and packet delay variation and so on.
Considering the several disadvantages indicated in the draft, I would like to provide following scheme to ease the disadvantages. 

As you pointed out, RTCP traffic in every link is proportional to the number of translators in the connection in the Global reporting mode as shown in Figure 1.
Considering the situation in Figure 1, I think that the multiplexing scheme of RTCP report blocks by the translators is useful to reduce the RTCP traffic as shown in Figure 2. 
The RTCP traffic might be the same that of the Local reporting mode as shown Figure 3.
The multiplexing scheme is a realistic approach by choosing a proper sending interval of the RTCP reports and the number of metrics blocks measured in the translators.

A.R/A.T------>J.1R/J.2T---->K.1R/K.2T---->L.1R/L.2T------>Z.R/Z.T

    |     RTP     |             |             |              |
    |<------------|-------------|-------------|------------->|
    |             |             |             |              |
    | RTCP(A.R)   | RTCP(A.R)   | RTCP(A.R)   | RTCP(A.R)    |
    |- - - - - - >|- - - - - - >|- - - - - - >|- - - - - - > |
    |             | RTCP(J.1R)  | RTCP(J.1R)  | RTCP(J.1R)   |
    |             |- - - - - - >|- - - - - - >|- - - - - - > |
    |             | RTCP(J.2R)  | RTCP(J.2R)  | RTCP(J.2R)   |
    |             |- - - - - - >|- - - - - - >|- - - - - - > |
    |             |             | RTCP(K.1R)  | RTCP(K.1R)   |
    |             |             |- - - - - - >|- - - - - - > |
    |             |             | RTCP(K.2R)  | RTCP(K.2R)   |
    |             |             |- - - - - - >|- - - - - - > |
    |             |             |             | RTCP(L.2R)   |
    |             |             |             |- - - - - - > |
    |             |             |             | RTCP(L.2R)   |
    |             |             |             |- - - - - - > |
    |             |             |             |              |

A.T/A.R<------J.1T/J.2R<----K.1T/K.2R<----L.1T/L.2R<------Z.T/Z.R

    |     RTP     |             |             |              |
    |<------------|-------------|-------------|------------->|
    |             |             |             |              |
    | RTCP(Z.R)   | RTCP(Z.R)   | RTCP(Z.R)   | RTCP(Z.R)    |
    |< - - - - - -|< - - - - - -|< - - - - - -|< - - - - - - |
    | RTCP(L.1R)  | RTCP(L.1R)  | RTCP(L.1R)  |              |
    |< - - - - - -|< - - - - - -|< - - - - - -|              |
    | RTCP(L.2R)  | RTCP(L.2R)  | RTCP(L.2R)  |              |
    |< - - - - - -|< - - - - - -|< - - - - - -|              |
    | RTCP(K.1R)  | RTCP(K.1R)  |             |              |
    |< - - - - - -|< - - - - - -|             |              |
    | RTCP(K.2R)  | RTCP(K.2R)  |             |              |
    |< - - - - - -|< - - - - - -|             |              |
    | RTCP(J.1R)  |             |             |              |
    |< - - - - - -|             |             |              |
    | RTCP(J.2R)  |             |             |              |
    |< - - - - - -|             |             |              |
    |             |             |             |              |
                  
               Figure 1 The Global reporting mode

A.R/A.T------>J.1R/J.2T---->K.1R/K.2T---->L.1R/L.2T------>Z.R/Z.T

    |     RTP     |             |             |              |
    |<------------|-------------|-------------|------------->|
    |             |             |             |              |
    | RTCP(A.R)   | RTCP(A.R)   | RTCP(A.R)   | RTCP(A.R)    |
    |- - - - - - >|- - - - - - >|- - - - - - >|- - - - - - > |
    |             |             |             | RTCP(J.1R,   |
    |             |             | RTCP(J.1R,  |      K.1R,   |
    |             | RTCP(J.1R)  |      K.1R)  |      L.1R)   |
    |             |- - - - - - >|- - - - - - >|- - - - - - > |
    |             |             |             | RTCP(J.2R,   |
    |             |             | RTCP(J.2R,  |      K.2R,   |
    |             | RTCP(J.2R)  |      K.2R)  |      L.2R)   |
    |             |- - - - - - >|- - - - - - >|- - - - - - > |

A.T/A.R<------J.1T/J.2R<----K.1T/K.2R<----L.1T/L.2R<------Z.T/Z.R

    |     RTP     |             |             |              |
    |<------------|-------------|-------------|------------->|
    |             |             |             |              |
    | RTCP(Z.R)   | RTCP(Z.R)   | RTCP(Z.R)   | RTCP(Z.R)    |
    |< - - - - - -|< - - - - - -|< - - - - - -|< - - - - - - |
    | RTCP(L.1R,  |             |             |              |
    |      K.1R,  | RTCP(L.1R,  |             |              |
    |      J.1R)  |      K.1R)  | RTCP(L.1R)  |              |
    |< - - - - - -|< - - - - - -|< - - - - - -|              |
    | RTCP(L.2R,  |             |             |              |
    |      K.2R,  | RTCP(L.2R,  |             |              |
    |      J.2R)  |      K.2R)  | RTCP(L.2R)  |              |
    |< - - - - - -|< - - - - - -|< - - - - - -|              |
    |             |             |             |              |

Figure 2 Proposed multiplexing scheme of the Global reporting mode

A.R/A.T------>J.1R/J.2T---->K.1R/K.2T---->L.1R/L.2T------>Z.R/Z.T

    |     RTP     |             |             |              |
    |<------------|-------------|-------------|------------->|
    |             |             |             |              |
    | RTCP(A.R)   | RTCP(A.R)   | RTCP(A.R)   | RTCP(A.R)    |
    |- - - - - - >|- - - - - - >|- - - - - - >|- - - - - - > |
    |             | RTCP(J.1R)  | RTCP(K.1R)  | RTCP(L.1R)   |
    |             |- - - - - - >|- - - - - - >|- - - - - - > |
    |             | RTCP(J.2R)  | RTCP(K.2R)  | RTCP(L.2R)   |
    |             |- - - - - - >|- - - - - - >|- - - - - - > |
    |             |             |             |              |
    |             |             |             |              |

A.T/A.R<------J.1T/J.2R<----K.1T/K.2R<----L.1T/L.2R<------Z.T/Z.R

    |     RTP     |             |             |              |
    |<------------|-------------|-------------|------------->|
    |             |             |             |              |
    | RTCP(Z.R)   | RTCP(Z.R)   | RTCP(Z.R)   | RTCP(Z.R)    |
    |< - - - - - -|< - - - - - -|< - - - - - -|< - - - - - - |
    | RTCP(J.1R)  | RTCP(K.1R)  | RTCP(L.1R)  |              |
    |< - - - - - -|< - - - - - -|< - - - - - -|              |
    | RTCP(J.2R)  | RTCP(K.2R)  | RTCP(L.2R)  |              |
    |< - - - - - -|< - - - - - -|< - - - - - -|              |
    |             |             |             |              |

                  Figure 3 Local reporting mode

Figure 4 depicts an example of the RTCP reports configuration of the proposed multiplexing scheme.

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                             Header                            |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
|                          Sender info                          |
|                                                               |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
|                       Report block of SSRC 1                  |
|                                                               |
|                                                               |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
|                            Chunk 1                            |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
|                          　HR header                          |
|                                                               |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
|                      Report blocks (Chunk 1)                  |
|                                                               |
|                                                               |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
|                                                               |
|                             …                                 |
|                                                               |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
|                            Chunk N                            |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
|                          　HR header                          |
|                                                               |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
|                      Report blocks (Chunk N)                  |
|                                                               |
|                                                               |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
 Figure 4 An example of the multiplexed RTCP reports packet（SR）

The report blocks are the same as for the standard RTCP XR reports.
The "last SR (LSR)" and "delay since last are used for calculating the 
RTT with the local time of sending RTCP report and receiving RTCP 
reports.

I am happy if I could have your comments.
Best regards,
Yama

***********************************
Hideaki YAMADA,
KDDI R&D Labs. Inc.
Tel/Fax : +81-49-278-7356/7510
[email-masked]
***********************************

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Audio/Video Transport Working Group
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