<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=iso-8859-1">
<META content="MSHTML 6.00.2800.1226" name=GENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY bgColor=#ffffff>
<DIV><FONT face=Arial>Ernst,</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Sorry for the delayed reply. I've been busy the
latter part of the week and just now catching up on some standards
e-mail.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Here's the problem:</FONT></DIV>
<UL>
<LI><FONT face=Arial>Suppose a T.38v2 devices calls a T.38v0 device, proposing
T.38v2 in Fast Connect.</FONT></LI>
<LI><FONT face=Arial>The called T.38v0 device will accept the T.38v2
proposal... there is no text to tell it not to.</FONT></LI>
<LI><FONT face=Arial>The called T.38v0 device returns a fastStart element
containing v2!</FONT></LI>
<LI><FONT face=Arial>The calling device then sends IFP packets encoded
according to the 2002 syntax,</FONT><FONT face=Arial> which will fail to
decode.</FONT></LI></UL>
<DIV><FONT face=Arial>If we had text in H.323 Annex D or elsewhere that said
that an endpoint shall not accept a proposal for a version higher than it
understands, that would be OK. However, we don't have such rules. If
we forced the endpoints to at least pass the capability set messages in the
Setup and response to Fast Connect, that would also address the issue... but we
don't have that requirement either.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>So, we need two things:</FONT></DIV>
<OL>
<LI><FONT face=Arial>We need to address this versioning issue quite
explicitly</FONT></LI>
<LI><FONT face=Arial>We need some "kludge" to allow v2 devices to work
properly with v0 devices that accept a v2 fastStart proposal</FONT></LI></OL>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Paul</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=ernst.horvath@siemens.com
href="mailto:ernst.horvath@siemens.com">Horvath Ernst</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=paulej@PACKETIZER.COM
href="mailto:'paulej@PACKETIZER.COM'">'paulej@PACKETIZER.COM'</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Cc:</B> <A title=itu-sg16@external.cisco.com
href="mailto:itu-sg16@external.cisco.com">itu-sg16@external.cisco.com</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Wednesday, September 17, 2003 4:55
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> AW: H.323 Fast Connect and
Versioning</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=794122408-17092003>Paul,</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=794122408-17092003></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=794122408-17092003>I
still don't see why the existing version field in the t38FaxProfile isn't
sufficient and how an additional syntax2002 field would help much.
</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=794122408-17092003></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=794122408-17092003>If
an old implementation returns an unrecognised version field, why should it
drop an unrecognised new field? So those implementations still won't behave as
expected. </SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=794122408-17092003></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=794122408-17092003>The
only case where syntax2002 would improve things seems to be with version
0/1 implementations that understand the version field and answer incorrectly
by returning a "version = 2" field unchanged. Am I right?</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=794122408-17092003></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=794122408-17092003>Ernst</SPAN></FONT></DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px solid; MARGIN-RIGHT: 0px">
<DIV><FONT face="Times New Roman" size=2>-----Ursprüngliche
Nachricht-----<BR><B>Von:</B> paulej@PACKETIZER.COM
[mailto:paulej@PACKETIZER.COM]<BR><B>Gesendet am:</B> Mittwoch, 17.
September 2003 06:26<BR><B>An:</B>
itu-sg16@external.cisco.com<BR><B>Betreff:</B> Re: H.323 Fast Connect and
Versioning</DIV><BR></FONT>
<DIV><FONT face=Arial>Anatoli,</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>So, I think the first step for T.38 is to add
the syntax2002 field. Following that, we need to go back and more
clearly define versioning issues for all sub-protocols, including T.38,
V.150.1, V.ToIP, V.VBD, etc. All of those will present similar
issues.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Paul</FONT></DIV>
<DIV><FONT
face=Arial></FONT> </DIV></BLOCKQUOTE></BLOCKQUOTE></BODY></HTML>