Subject: Query on MegacoVsMgcp Doc

From: Sarika Gupta <[email-masked]>
Date: Wed, 25 Apr 2001 06:53:13 +0100 (BST)

Hi,
I have a query regarding one of the points of
differences between Megaco and MGCP in the 
ftp://standards.nortelnetworks.com/megaco/docs/Related/MegacoVsMGCPv1.pdf.
It is regarding "Handling of internal resources".
Under this point it is mentioned that the internal
resources such as DTMF Tone generator is treated as
separate termination. Now considering the scenario
that this resource is just another hardware chip for
generating tones within the same MG which contains the
terminations where the tones have to be actually
played, do we need to treat it as a separate
termination in Megaco or just the internal hardware
connectivity between the actual physical terminations
and this hardware would suffice.

Regards
sarika

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---

From: "Rosen, Brian" <[email-masked]>
Date: Wed, 25 Apr 2001 08:06:12 -0400

In general, you need a protocol construct to represent
resources that are dependent on what we call a "context".  
You need a termination to represent a set of media streams 
that are related to one another.

You don't need a termination to represent a resource
that can be shared among several "calls".  Your
example of a DTMF Tone generator could be a resource which
is associated with a termination, but not independently
of the resources that create, for example, connections
to a physical analog line.  The same termination
represents the line and the DTMF generator.

If the MG has multiple lines, you could have independent
DTMF generators for each line, or you could have a
shared resource.  To the MGC this is invisible - the
tone generators are part of the resources associated with
each line, and are instructed on a per line (really,
per termination) basis, when to generate tones and what
tone to generate.

Contrast this with a tones and announcement server.
This might be an MG independent of the line MGs.  Here,
the tone generator is not attached to the line termination,
it's in an entirely separate MG.  The MGC can't just tell the
line termination to generate a tone, it has to construct a
media path (say RTP) between the MG with the line termination
and the MG with the tone generator.  To do so, the tones
and announcements server instantiates some number of terminations
that represent independent connections to the tone generator.
The MG would also instantiate terminations representing
the RTP flows.  The MGC, when it wanted to play a tone on a
line would tell the line MG to create a two termination context
containing the line termination and an ephemeral RTP termination.
The latter would be directed to the tones and announcements
MG.  The tones and announcements MG would be instructed to
create a two termination context with one "port" of the tone
generator, and an RTP ephemeral towards the lines MG.  The
line would receive the tone, streamed across the network.

Now, one question arises.  Should the tones and announcements
MG use physical or ephemeral terminations?  It could use either.
If the MG has a hard, physical limit on how many "ports" it has,
it might be better to use a physical termination.  Often, however,
a DSP is used, and the number of "ports" is somewhat harder to
define -- it may be easy to have a large number of listeners to
a small number of different tones, but hard to have a large
number of tones to a small number of listeners each.  In that case,
ephemeral terminations for the tone generator might be appropriate.

Brian

> -----Original Message-----
> From: Sarika Gupta [mailto:[email-masked]]
> Sent: Wednesday, April 25, 2001 1:53 AM
> To: [email-masked]
> Subject: Query on MegacoVsMgcp Doc
> 
> 
> Hi,