Subject: [Megaco] correct connection model for conferencing according darft H.248.1 9

From: Kalleitner Franz <[email-masked]>
Date: Tue, 10 Jun 2003 14:15:32 +0200

Hello megaco-list-members

In the past, many threats were discussing about conferencing. However SG16
started to summarized this topic in the draft H.248.19 (BTW: Thanks a lot
for that work), but the connection model is still not clear to me.
As documented in H.248.19 §5 (conferencing architectures) it is mentioned
that according H.248 §6 two different types of conferencing could apply by
placing the relevant terminations in the same or different contexts.

In case of implementing conferences using different contexts, which
connection model should apply ?
1.) for each conferee an own context as shown at example §9
draft-ietf-megaco-callflows-02.txt?
2.) separation into a central conference context and for each conferee an
own, lets say, call leg context?
3.) or are both listed connection models meaningful ?

The second approach was discussed many times in the list, but there was
never a final and clear statement, may be there could be one before
finalizing H248.19.

Thanks in advance
Franz

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From: Christian Groves <[email-masked]>
Date: Wed, 11 Jun 2003 11:43:12 +1000

Hello Franz,

I believe the correct approach is the model where all terminations for a
centralised conference belong to '1' context.

However in some conferencing scenarios a hybrid approach with more than one
context would be needed. Take for example when you have a centralised conference
and someone is put on hold. According to the H.248 connection model a seperate
context is needed. So therefore you have a hybrid with 2 contexts. Another
example is when you have a main conference in one context and side context in
another context. Rather than moving all the participants a seperate call leg
termination in both contexts could be used to join the conferences. 

This is why H.248.19 makes the statement "By placing the relevant terminations
in the same or different contexts it allows the MCU to perform the different
types of  "multi-point". 

If you also wanted to model the conference bridge as a central context with a
side context for each call leg then I believe that due to the fact that hybrid
approach should be supported then this model is also supported.

The packages in H.248.19 support the above configurations.

I believe the configuration/model for conferencing in
<draft-ietf-megaco-callflows-02.txt> is incorrect and I do not believe that the
H.248.19 package support this model. Whilst the draft is quite voluminous I
would caution people using the call flows as gospel and I would certainly not
base an implementation on them.

Regards, Christian

Kalleitner Franz wrote:
> started to summarized this topic in the draft H.248.19 (BTW: Thanks a lot for
> that work), but the connection model is still not clear to me.
> 
> As documented in H.248.19 §5 (conferencing architectures) it is mentioned that
> according H.248 §6 two different types of conferencing could apply by placing
> the relevant terminations in the same or different contexts.
> 
> In case of implementing conferences using different contexts, which connection
> model should apply ?
> 2.) separation into a central conference context and for each conferee an own,
> lets say, call leg context?
> The second approach was discussed many times in the list, but there was never
> a final and clear statement, may be there could be one before finalizing
> H248.19.
> 
> Thanks in advance
> Franz

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From: Christian Groves <[email-masked]>
Date: Wed, 11 Jun 2003 11:43:12 +1000

Hello Franz,

Regards, Christian