[xrblock] Open issue- identity info repetition in draft-ietf-avtcore-monarch

[Qin Wu <[e-mail]>]

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