Enforcing symmetric operation in the context of slow start fo r H. 323v4

[Roni Even]

Hi,
I think the issue is very important, there is no clear way to achieve
symmetric operation today.
In H.323 it states that if a terminal supports H.263 CIF it implies that it
support H.261 CIF. On the other hand it states that a terminal can use the
receive capabilities to signal which codec it supports, it is not clear if
for example a terminal signal that it can receive H.263 CIF, if the
transmitter can send H.261 CIF since it is implied but is less preferable,
or does it mean that it can only receive H.263 CIF.
I think that we can use this change also to make the text correct at least
for the symmetric mode. It should state that these are the modes that the
terminal can do in symmetric mode and not the implied ones.
Roni Even
-----Original Message-----
From: Mike Nilsson [mailto:mike.nilsson at BT.COM]
Sent: Thursday, September 07, 2000 11:47 AM
To: ITU-SG16 at MAILBAG.INTEL.COM
Subject: Enforcing symmetric operation in the context of slow start for
H. 323v4


At the Portland rapporteur's meeting of Q12-14, document APC-1881,
'Enforcing symmetric operation in the context of slow start for H.323v4',
was discussed. The outcome of the discussion, as described in the meeting
report, is:

        This was accepted for the H.323 IG and also H.323 V4.   It was
agreed that this was meritorius, but that some further discussion was
needed. See TD-47.  The agreement is that APC-1881 is adopted for changes to
H.323 V4, and TD-47 for H.245 V7, with the redefinition of the
receiveAndTransmitt capability being the preferred approach. It was noted
that the rejectReason needs to be mentioned in TD-47. Text will also be
added to note that the procedures of TD-47 only apply if the slave has
detected a conflict.  All are urged to look very closely at this, and to
consider if there are any issues with this.  If any are found, we will make
changes in November. The editor will post this discussion on the mailing
list to ensure broad discussion.

The purpose of this mail is simply to do as the meeting report stated, and
highlight the issue and to try to get broad agreement on the proposed
solution. As far as H.245 is concerned the proposed solution is to include
text from TD-47a that is labelled as 'Proposal for immediate action' and the
first option (redefinition of the receiveAndTransmitt capability) from the
section labelled 'Longer term options'.

The documents are available at:

        ftp://standard.pictel.com/avc-site/0008_Por/APC-1881.zip
        ftp://standard.pictel.com/avc-site/0008_Por/TD-47a.zip

Best regards

Mike Nilsson

--------------------
Mike Nilsson
Multimedia Applications
B81 Room 102 pp14
BT Advanced Communications Technology Centre
Adastral Park, Martlesham Heath, Ipswich, IP5 3RE, UK
Tel:    +44 1473 645413
Mobile: +44 7808 635412
Fax:    +44 1473 646589
Email:  mike.nilsson at bt.com

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