Subject: [Megaco] partially specified ephemeral

From: "Raphael Tryster" <[email-masked]>
Date: Sun, 29 Apr 2007 18:01:24 +0200

I have a question concerning an application in which an MG has the
ability to create ephemeral terminations having a local IP address
chosen from one of several subnets.  At the time that the Add command is
sent, the MGC knows the subnet in which it wants the ephemeral created,
but does not yet know the exact remote SDP.  I can think of about 4 ways
this might be done.

1.  Is there such a thing as a partially specified address in
Megaco-flavoured SDP, e.g. "c=IN IP4 192.168.5.$"?  This would be a way
for the MGC to say it wants the MG to choose a local address of the form
192.168.5.x.

2.  There was a discussion several years ago (Add with Choose) about
whether the MGC could partially specify the name of an ephemeral
termination, e.g. "subnet/1/$", which would be provisioned on both sides
such that "subnet/1" implies the 192.168.5.x subnet.  I don't know how
that discussion was resolved and whether this is a permitted format.

3.  The MGC could hint to the MG that it wants it to choose an ephemeral
with a local address from a given subnet, by supplying a remote
descriptor with a fictitious address in that subnet.  The mode would be
inactive until the MGC is ready to supply the real remote SDP in a
Modify command.

4.  In the Add with Choose discussion, the possibility was also raised
about using a package to define ephemeral termination types.  Was such a
package defined?

Comments about the validity and interoperability of the above options,
or additional ones, would be appreciated.

Raphael Tryster

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From: Christian Groves <[email-masked]>
Date: Mon, 30 Apr 2007 17:50:47 +1000

G'Day Raphael,

Please see my responses below marked CNG.

Regards, Christian

> for the MGC to say it wants the MG to choose a local address of the form
[CNG] I don't think this is possible. H.248.39 specifies that sub-fields 
shouldn't be partially wildcarded.
> that discussion was resolved and whether this is a permitted format.
[CNG] This is possible but would require provisioning as you mentioned.
> inactive until the MGC is ready to supply the real remote SDP in a
[CNG] Sounds a bit messy.
> about using a package to define ephemeral termination types.  Was such a
[CNG] There hasn't been a ephemeral termination type package defined 
that I know of.
> or additional ones, would be appreciated.
[CNG] Have you looked at the possibility of using H.248.41? Its used to 
indicate which IP domain a termination should be connected to.

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From: "Raphael Tryster" <[email-masked]>
Date: Mon, 30 Apr 2007 15:17:50 +0200

Looks useful, thank you.  I can always rely on you for good answers on a
Monday morning. 
 
Raphael Tryster

-----Original Message-----
From: Christian Groves [mailto:[email-masked]] 
Sent: Monday, April 30, 2007 9:51 AM
To: Raphael Tryster
Cc: [email-masked]
Subject: Re: [Megaco] partially specified ephemeral

G'Day Raphael,

Regards, Christian