H.323 Annex D

[Francois Audet]

Paul, do you have a copy of H.245v3? All I can find are v1, v2, v4, v5,
v6...

-----Original Message-----
From: Paul E. Jones [mailto:paul.jones at TIES.ITU.INT]
Sent: Monday, February 28, 2000 9:13 PM
To: ITU-SG16 at MAILBAG.INTEL.COM
Subject: Re: H.323 Annex D


Francois,

Actually, I went back to look and we do allow newer versions of H.245 to be
used with H.323v2 systems.  It was inserted into the H.323 IG in May 1999
and is also in H.323v3.  Unfortunately, the text is not as clear as it
should be.  That's something I will address.

You are correct that new additions were made to H.245v6 (as confirmed by
Mike Nilsson) to support T.38.  I don't recall now what the specific issue
were: whether H.245v4 would not work at all or whether the additions were
merely improvements.  I do remember that at one point, Annex B/T.38 has
ASN.1 that differed from H.245-- that was certainly an issue.  As far as I
know, though, Annex D/H.323 will work with H.245v4.

Can anyone else comment?

I will seriously consider pulling Annex D into the main document.  It makes
my life a bit easier, too.  However, I suppose it's worth noting which
version of H.323 an Annex will work with in general.  I have had similar
inquiries about Annex E and Annex F.  Perhaps a new section in the
Implementers Guide is in order to address those issues?

Paul


----- Original Message -----
From: Francois Audet <mailto:audet at NORTELNETWORKS.COM>
To: ITU-SG16 at mailbag.cps.intel.com <mailto:ITU-SG16 at mailbag.cps.intel.com>
Sent: Monday, February 28, 2000 12:18 PM
Subject: Re: H.323 Annex D


By default, I believe that editor would be me.  This annex was intended to
work with H.323v2 systems and later, but you are correct that there was no
way to specify T.38 until H.245v4.

Of course, H.323v2 systems used H.245v3.  H.323v3 systems used H.245v3 or
higher (the key element).  So, I suppose the question is: is H.323v3
required?  Surely not, as there are implementations out there.  We have
argued about whether H.323v2 systems could use later versions of H.245.  The
outcome was "no"-- perhaps that needs to be revisited.

Interesting: I tought H.323v2 used H.245v2... Side issue anyways.

There have been recent changes to H.245 ASN.1 to support T.38.  At least
there have been some proposed changes.  Unfortunately, I missed much of that
discussion.  The meeting report says that those changes were added to
H.245v6.

Mike, is it true that the T.38-related changes from H.245v4 to H.245v6 were
nothing more than additions to H.245-- not "changes", per se.  Also, did the
proposed changes (from TD8/WP2, I believe) make it into H.245v6?

My understanding would be that the changes were introduced in H.245v4, but
had mistakes that were corrected in H.245v6.

As for Annex D, I am considering just pulling that into the H.323 document,
rather than keeping it as a separately published annex-- does anybody object
to that?  That would certainly address questions related to references going
forward.  However, we need to reach a decision about the current
publication.  I suspect we need something for the IG, but the problem is
that H.323v2 is "old news" now.  What to do....

I would support including Annex D in the main H.323v4 document (wich would
imply H.245v6).

The other alternatives would be to mandate H.323v4/H.245v6 in Annex D. But I
prefer the first alternative.

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