Subject: RE: Loopback mode of a fixed Termination

From: "Tom-PT Taylor" <[email-masked]>
Date: Wed, 18 Jul 2001 12:01:36 -0400

Maybe I shouldn't confuse matters, but I always thought of loopback as being
a state where the media would be available to that one termination only.  It
is typically going to be used in testing situations, so the question is
whether such situations demand propagation through the context as well as
back to the source.

-----Original Message-----
From: Sean Leahy [mailto:[email-masked]]
Sent: Monday, July 02, 2001 6:51 AM
To: Christian Groves
Cc: Brian Rosen; [email-masked]'
Subject: Re: Loopback mode of a fixed Termination

Christian,
     Oops ! I see now what you mean. Of course the mode of the termination
is
with respect to the exterior of the context (in both the case of a fixed
Termination or an ephemeral Termination).

     So you are quite right to say that it is by virtue of the reception of
media from the exterior of the termination into the context that the
loopbacked
media can then fan-out from the context to another exterior  via the
ephemerals
(if they in turn, have a sending mode).

     The alternative view would be that one of the differences between
loopback
and send/receive is that media flows in and out of the termination without
being
visible to the rest of the context. However, both Brian and yourself do not
think that is the correct interpratation.

     Thanks,
     Sean
---------------------- Forwarded by Sean Leahy/MAIN/MC1 on 02/07/2001 11:39
---------------------------

(Embedded image moved to file: pic11702.pcx)
From: Sean Leahy On: 02/07/2001 09:31:53

To:   Christian Groves <[email-masked]> @ MCEXT
cc:   Brian Rosen/MAIN/MC1@MSEXCH, "[email-masked]'" <[email-masked]>

Subject:  Re: Loopback mode of a fixed Termination  (Document link: Sean
Leahy)

Christian,
     Sorry, but this has confused me a little. I expected that the loopback
mode
of a termination implies that either:

     a. Media is entirely to and from the termination without any visibility
to
the rest of the context or

     b. Media sent out from the loopback termination, goes through the
context
on the way back to the termination.

     If b., then it would be by virtue of the sending of media from A that
the
media is also fanned-out to c. i.e. not by virtue of the receiving of media
at
A.

     If this assumption is wrong, can you clarify ?

     Thanks,
     Sean

Christian Groves <[email-masked]> on 02/07/2001 07:55:03

                                                              

 To:       Brian Rosen/MAIN/MC1@MSEXCH                        
                                                              
 cc:       Sean Leahy/MAIN/MC1@MCMAIN, "[email-masked]'"    
           <[email-masked]>                                  

 Subject:  Re: Loopback mode of a fixed Termination           

G'Day Brian,

I have the same opinion. Loopback is essentially putting a wire
between send and receive on Tid=A. So what you send on A you receive on
A. Thus if you receive on A it gets passed to C.

Christian

"Rosen, Brian" wrote:
>
> Hmm, seem to have missed that.
>
> It's not entirely clear to me.  There are a couple of hints in the text
that
> suggest that
> indeed it does.  The most telling is:
>      If the Mode property of the LocalControl descriptor is RecvOnly,
>      SendRecv, or Loopback, the MG must be prepared to receive media
>      encoded according to any of the alternatives included in its
>      response to the MGC.
> I would say that yes, loopback implies data is sent towards the Context.
> Inactive or RecieveOnly would not.
>
> Anyone got a different opinion?
>
> Brian
>
> >  -----Original Message-----
> > From:         Leahy, Sean
> > Sent: Friday, June 29, 2001 12:00 PM
> > To:   Rosen, Brian
> > Subject:      Loopback mode of a fixed Termination
> >
> > Brian,
> >       Have you seen this question ?
> >
> >       Sean
> > ---------------------- Forwarded by Sean Leahy/MAIN/MC1 on 29/06/2001
> > 16:59 ---------------------------
> >
> >  <<...OLE_Obj...>>
> > From: Sean Leahy On: 29/06/2001 09:07:52
> >
> > To:   Brian Rosen/MAIN/MC1@MSEXCH
> > cc:   [email-masked]
> >
> > Subject:      Loopback mode of a fixed Termination
> >
> > Brian,
> >       Can you confirm that if a fixed Termination A with a mode of
> > Loopback, is in an H.248 Context (default star topology) that also
> > contains an ephemeral in send only mode, connected across the network to
C
> > then (all being equal at C's end) C should hear the data being sent from
A
> > to A ?
> >       Thanks,
> >       Sean

---

From: "Madhu Babu Brahmanapally" <[email-masked]>
Date: Wed, 18 Jul 2001 15:16:25 -0400

RE: Loopback mode of a fixed TerminationHI Tom,All,
It seems true in the first glance that loopback will be performed only on
the specified termination. Lets consider a simple example, where two
terminations are in context. we don't explicitly say that data has to be
exchanged between the terminations in the given context. (The default
topology of a Context is that each  termination's transmission is received
by all other terminations.) Extending the same case loopback mode is no
different. Mode of a termination is defined to dictate the flow of media at
the ingress/egress. But the in-context flow is controlled by the Topology
descriptor.

In such cases where loopback is to be performed on one of the two(or more)
terminations in the context, the MGC can control by using the Topology
descriptor. If the MGC intends to keep the mode to loopback and doesn't
worry about other terminations hearing the same...then the topology
descriptor need not be used. (Only tricky thing is that the Topology
descriptor is optional to implement). So, by considering the behavior of
contexts, topology, termination modes.... in such situations propagation
through the context as well as back to the source seems logical.

Regards
Madhubabu

 -----Original Message-----
From: [email-masked]
[mailto:[email-masked]]On Behalf Of Tom-PT Taylor
Sent: Wednesday, July 18, 2001 12:02 PM
To: 'Sean Leahy'; Christian Groves
Cc: Brian Rosen; [email-masked]'
Subject: RE: Loopback mode of a fixed Termination

  Maybe I shouldn't confuse matters, but I always thought of loopback as
being a state where the media would be available to that one termination
only.  It is typically going to be used in testing situations, so the
question is whether such situations demand propagation through the context
as well as back to the source.

  -----Original Message-----
  From: Sean Leahy [mailto:[email-masked]]
  Sent: Monday, July 02, 2001 6:51 AM
  To: Christian Groves
  Cc: Brian Rosen; [email-masked]'
  Subject: Re: Loopback mode of a fixed Termination

  Christian,

       So you are quite right to say that it is by virtue of the reception
of
  media from the exterior of the termination into the context that the
loopbacked
  media can then fan-out from the context to another exterior  via the
ephemerals
  (if they in turn, have a sending mode).

       The alternative view would be that one of the differences between
loopback
  and send/receive is that media flows in and out of the termination without
being
  visible to the rest of the context. However, both Brian and yourself do
not
  think that is the correct interpratation.

       Thanks,
       Sean
  ---------------------- Forwarded by Sean Leahy/MAIN/MC1 on 02/07/2001
11:39
  ---------------------------

  Christian,
       Sorry, but this has confused me a little. I expected that the
loopback mode
  of a termination implies that either:

       a. Media is entirely to and from the termination without any
visibility to
  the rest of the context or

       If b., then it would be by virtue of the sending of media from A that
the
  media is also fanned-out to c. i.e. not by virtue of the receiving of
media at
  A.

       Thanks,
       Sean

  G'Day Brian,

  Christian

that
  > > contains an ephemeral in send only mode, connected across the network
to C
  > > then (all being equal at C's end) C should hear the data being sent
from A