Re: [xrblock] Tags and SSRC's in XR Blocks

Hi Alan,

draft-clark-xrblock-rtcp-xr-qoe-00 has a 6-bit tag while the Measurement ID
block defines it as a 3-bit identifier.

In draft-ietf-avt-rtcp-xr-meas-identity-02#section-2: there is a 0 bit, is
this done so that the Tag field aligns across blocks? if so then there
should be 2 zero bits to cover for the new I field.

Also in the measurement identity draft:

Bits shown as '0' in the figure SHOULD be set to zero.

SHOULD be MUST?

Cheers,

Varun

On Fri, Nov 18, 2011 at 12:57, Charles Eckel (eckelcu) <eckelcu@cisco.com>wrote:

> Hi Alan,
>
> As this issue concerns the monarch draft as well as the measurement
> identification block draft, it was discussed on both the avtcore and
> xrblock lists:
>
> http://proxy2974.my-addr.net/myaddrproxy.php/http/www.ietf.org/mail-arch
> ive/web/avt/current/msg14582.html
> and
> http://proxy2974.my-addr.net/myaddrproxy.php/http/www.ietf.org/mail-arch
> ive/web/avt/current/msg14658.html
>
> The decision at that time was to remove the tag and rely on the SSRC.
> The thread speaks to point (i) you raised. It does not speak to point
> (ii).
> Point (ii) was raised during the xrblock working group session with
> week, and one of the action items for the measurement identification
> draft was to clarify the intended usage of the measurement identity
> block in such cases.
>
> Cheers,
> Charles
>
> > -----Original Message-----
> > From: xrblock-bounces@ietf.org [mailto:xrblock-bounces@ietf.org] On
> Behalf Of Alan Clark
> > Sent: Wednesday, November 16, 2011 11:27 AM
> > To: xrblock@ietf.org
> > Subject: [xrblock] Tags and SSRC's in XR Blocks
> >
> >
> > The original concept for the XR blocks used the idea of a Tag to
> relate the metrics blocks to a
> > measurement identification block.  This approach was used for a number
> of reasons:
> >
> > (i) It is more efficient as the Source SSRC, which is already in the
> measurement identification block,
> > does not have to be repeated for every metrics block.  As some of the
> metrics blocks are only 3-4
> > words in size, the redundant SSRC increases the message size by
> 25-30%.
> >
> > (ii) It provides more flexibility in the organization of metrics
> blocks into RTCP packets - allowing
> > either one RTCP packet to contain several sets of measurement data or
> allowing one set of measurement
> > data to be carried over several RTCP packets.
> >
> > I'm not sure why the Tag was removed - was there some good technical
> reason for this?
> >
> > Alan
>
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-- 
http://www.netlab.tkk.fi/~varun/