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Re: [MEDIACTRL] Direct Phone Call Call-Flow

I could see something like this as part of an advanced conferencing package. However, I would offer it is out of scope for the current IVR and MIXER packages. 

Any thoughts from the rest of the work group?

On Aug 12, 2009, at 5:46 AM, Rusu Andreea-B00553 wrote:


Hi,

I do agree with you that MEDIACTRL should not address the DSP
allocation/management business. The Media Server alone is responsible
with this.

What I am suggesting is to allow the Media Server to renegotiate the
connection settings (maybe even codecs) for a certain media connection. For example, if one connection was created with an INVITE received from 
AS, later on the MS should be able to send a re-INVITE for the same
connection to change the IP address or UDP port on his side.

There may be situations when the Media Server needs to perform
internally some resources re-allocations (for load balancing or for
optimizations) which would require changes in the connection settings of a certain media connection (the scenario presented in the initial email 
is such an example). Another plausible scenario is when one DSP stops
and the Media Server is recovering by restoring the media connections to 
a new DSP (another network entity). This could have the side effect of
changing the IP addresses of the restored connections.

With H.248 the context is first created and then the terminations are
added to that context. So the Media Gateway could easily allocate the
terminations belonging to the same context on the same network resource.
With MEDIACTRL the media connections are created first and then they are joined together or with a mixer. Even if the mixer is created before the 
media connections, as far as I know, there is no way for the Media
Server to know that the media connections will be joined later with that 
mixer or another.
So, I do agree that the AS should not tell MS where to create the
connections but in case MS needs to move some connections internally
from one network entity to another it should be able to announce the AS 
of this change.
The MEDIACTRL standards are not forbidding or allowing the renegotiation 
(re-INVITE) of a media connection by a Media Server. I believe this
could create interoperability problems and it would be useful to be
clarified.


Andreea Rusu

-----Original Message-----
From: Eric Burger [mailto:eburger at standardstrack.com]
Sent: Tuesday, August 11, 2009 9:26 PM
To: Rusu Andreea-B00553
Cc: mediactrl at ietf.org
Subject: Re: [MEDIACTRL] Direct Phone Call Call-Flow
Step 6 is totally behind the curtain. MEDIACTRL explicitly will not get to the DSP allocation / management business. Even H.248 will not allow 
for that level of control.
That said, an intelligent controller should be able to figure out if you 
allocate the mixer first, then maybe everything should be on the same
DSP.

On Aug 11, 2009, at 8:24 AM, Rusu Andreea-B00553 wrote:


Hi,

I have been studying the mediactrl drafts lately and I have the
following question.

Is  the scenario described below for a direct phone call valid from
the mediactrl framework perspective? This scenario is based on the
call flow presented in the draft-ietf-mediactrl-call-flows-01 draft
from chapter 6.2.1 Direct Connection.

   1) AS requests MS to create a media connection for UAC1 using SIP
Signaling.
   2) MS allocates resources for the UAC1 connection on one DSP
device.
   3) AS requests MS to create a media connection for UAC2 using SIP
Signaling.
   4) MS allocates resources for the UAC2 connection on another DSP
device (e.g. there is no room left on the previous DSP).
   5) AS requests MS to join UAC1 connection with UAC2 connection
using the Control Channel.
   6) MS can join the connections only if they are located on the
same DSP. By reducing the internal media traffic between two DSP
devices the I/O         processing on the DSP is also reduced thus
allowing more external media streams to be handled with the same
processing power. So MS decides to move the media connection of UAC1
to the second DSP. In this case the media IP Address and/or the UDP
port for the UAC1 connection will change. MS needs to inform AS of
this change by sending a re-INVITE.
       Once the re-Invite is accepted by AS, MS will join the two
connections and acknowledge the Join command on the Control Channel.

If this is a valid scenario, should it be specified in the standards
that the MS can renegotiate the connection settings (maybe also
codecs?) after a media connection was already created?

Thank you in advance,
Andreea Rusu
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