Proposed text for text telephone requirements in megaco

[Gunnar Hellstrom]

I don't believe there was any APC.  I introduced some ideas and proposed
text on the mailing list.  The text was revised in response to ensuing
discussion and Jim inserted it into the IG draft.  I agree it seems 
contradictory.  The way it was written had changed "shall be the 
first message sent" to "should be the first message sent".  The intention
was that you wouldn't have to send TCS, but if the peer got totally
confused about what was going on without it, the exchange would take
place.  

I believe that the Monterey meeting rejected my "shall" to "should" 
change but accepted everything else.  I unfortunately wasn't present 
while this item was discussed.  However, notice that in the last 
sentence of the paragraph, the EP "shall" respond to the TCS, and only
"should" complete a caps exchange before doing anything else.  So the EP
can still do things essentially in parallel.

As an aside, my belief is that other H.245 procedures besides MSD may be 
initiated prior to completion of caps exchange, for example, OLC.

Regards,
 
Dave Walker
Mitel Corporation
Ontario, CANADA

Chris Purvis wrote:
> 
> Paul,
> 
> No.  I think it comes out of things Dave was talking about.  Do you recall,
> Dave?
> 
> By the way, you guys may as well be the first to know (I'll email the lists
> at some point): I'll moving on from Madge in two and a half weeks time, and
> although I'll still be in the telecoms industry I don't expect to be active
> in the H.323 arena, at least for a while.
> 
> Chris
> 
> > -----Original Message-----
> > From: Paul E. Jones [mailto:paul.jones at ties.itu.int]
> > Sent: 23 June 1999 2:03
> > To: Chris.Purvis at MADGE.COM; pete at TECH-KNOW-WARE.COM
> > Subject: Re: Re: Question about text in implementers guide
> >
> >
> > Chris,
> >
> > Do you recall what APC introduced the text?
> >
> > Paul
> >
> > ----- Original Message -----
> > From: Chris Purvis <Chris.Purvis at MADGE.COM>
> > To: <ITU-SG16 at MAILBAG.INTEL.COM>
> > Sent: Wednesday, June 23, 1999 7:00 AM
> > Subject: Re: Question about text in implementers guide
> >
> >
> > > Pete,
> > >
> > > The background is that there should be no good reason for
> > not tunnelling
> > TCS
> > > and MSDet into the same H.225 message.  I agree that the
> > wording ought to
> > be
> > > improved (I heard or suggested at Monterey two or three
> > alternatives that
> > I
> > > consider better than the one you quote).
> > >
> > > Regards,
> > > Chris
> > >
> > >
> > > > -----Original Message-----
> > > > From: Pete Cordell [mailto:pete at TECH-KNOW-WARE.COM]
> > > > Sent: 22 June 1999 9:54
> > > > To: ITU-SG16 at MAILBAG.INTEL.COM
> > > > Subject: Question about text in implementers guide
> > > >
> > > >
> > > > Dear All,
> > > >
> > > > The following revised paragraph seems to have been added to
> > > > H.323 v3 via the
> > > > implementers guide.
> > > >
> > > > Endpoint system capabilities are exchanged by transmission of
> > > > the H.245
> > > > terminalCapabilitySet message. This capability message shall
> > > > be the first
> > > > H.245 message sent. If prior to successful completion of
> > > > terminal capability
> > > > exchange, any other procedure fails, (i.e. rejected, not
> > > > understood, not
> > > > supported) then the initiating endpoint should initiate and
> > > > successfully
> > > > complete terminal capability exchange before attempting any
> > > > other procedure.
> > > > An endpoint which receives a terminalCapabilitySet message
> > > > from a peer prior
> > > > to initiating capabilities exchange shall  respond as
> > > > required by 6.2.8.1,
> > > > and should initiate and successfully complete capabilities
> > > > exchange with
> > > > that peer prior to initiating any other procedure.
> > > >
> > > > I'm a bit confused about what it is saying.  It seems to be
> > > > saying that an
> > > > endpoint can send a TCS and prior to receiving the Ack, send
> > > > MSD (as there
> > > > is really no other procedure that can fail).  This is a
> > good thing.
> > > > However, it then says, that if for some reason you receive
> > > > TCS before you
> > > > yourself have sent one, then, I think the paragraph is saying
> > > > that, you must
> > > > send your own TCS, and are not allowed to do MSD until you
> > > > get the TCS Ack
> > > > back.  This is a bad thing.  But worse still there seems to
> > > > be conflicting
> > > > information for what is essentially a minor timing issue.
> > > > Could someone
> > > > kindly explain to me what the background to it is.
> > > >
> > > > Thanks,
> > > >
> > > > Pete
> > > >
> > > > =============================================
> > > > Pete Cordell
> > > > pete at tech-know-ware.com
> > > > =============================================
> > > >
> >
>