Subject: Re: GK to MGC interaction

From: Tom-PT Taylor <[email-masked]>
Date: Mon, 30 Aug 1999 14:09:10 -0500

SG 16 has a different architectural view from the IETF.  MGC/MG/SG are IETF
terms.  By definition, the SG function mediates legacy SCN signalling, so
the H.323 Gatekeeper has no business talking to it.  According to the IETF
view, the MGC is where all call signalling terminates and interworking is
done, so this would include H.225.0/Q.931 signalling.  Again according to
the IETF view, H.245 could terminate either in the MGC or in the MG, but
termination in the MG is out of scope of the Megaco charter.  (It is a
legitimate possibility for SG 16 to work on, however, and should be in H.248
if anyone is serious about implementing an H.320-to-H.323 gateway.)  That
leaves H.225.0/RAS as the only other type of signalling the H.323 Gatekeeper
supports.  I think everyone would agree that that should go to the MGC.

Remember that Megaco/H.248 has to do with intra-gateway control, not call
signalling.  Leaving aside the H.320-to-H.323 gateway case, all Gatekeeper
signalling would go to the MGC, which would create Megaco/H.248 messages as
required to provide the services the signalling is requesting.

> -----Original Message-----
> From: Udaya Shankara [SMTP:[email-masked]]
> Sent: Monday, August 30, 1999 8:20 AM
> To:   [email-masked]
> Subject:      GK to MGC interaction
>
> Hi all,
>          I have a doubt here regarding how an H.323 GK talks to a bunch of
> MGs controlled by a MGC. I assume that the SG functionality is
> incorporated
> into the MGC and MG. (Is this assumption correct?). Now if the GK wants to
> send some signalling information, how does it do? Does the GK interact
> with
> the MGC (through H.323) only or does it talk to the MG involved?
>
>          First of all, can the MGC support H.323?  If yes, it means
> conversion of H.323 to MEGACO signals and vice versa. Any info on this
> will
> be highly appreciated.
>
> Thanks and regards,
> Udaya

---

From: Mike Buckley <[email-masked]>
Date: Tue, 31 Aug 1999 11:01:41 +0000

>MGC/MG/SG are IETF
>the H.323 Gatekeeper has no business talking to it.

I think the terms MGC, MG and SG are now widely recognised and used by ITU,
ETSI TIPHON and other groups as well as IETF.  The work of ETSI TIPHON is
probably the most advanced on VoIP architectures, particularly in relation to
H.323 systems, although I think much of the work is fairly general.  See
DTS/TIPHON-02003 v. 0.2.1  for general architectures and and DTS/TIPHON-
02007 v.0.0.0. for interfacing to back-end services at http://www.etsi.org/docbox.
The documents can be found in the ftp area of the TIPHON pages and are listed
under the heading 07-drafts.

Mike

____________________ Begin Original Message
___________________________
Date: Mon Aug 30 14:09:10 -0500 1999
From: internet!NORTELNETWORKS.COM!taylor (Tom-PT Taylor)
Subject: Re: GK to MGC interaction
To: internet!STANDARDS.NORTELNETWORKS.COM!MEGACO
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