MGCP reference (was Re: Megaco/H.gcp conference call)

Tom-PT Taylor taylor at NORTELNETWORKS.COM
Wed Jun 30 09:53:46 EDT 1999

Here's a brief history, from my point of view -- others are free to add
their viewpoints.

April 1998: Bellcore announces SGCP (Simple Gateway Control Protocol).  They
have been prototyping for several months.  Hong Liu was one of the
participants.  I have the impression that many of the ideas came from
Christian Huitema, including the use of SDP, the separation into local and
remote descriptors which are effectively negotiated between MGs, and the use
of application-level framing instead of a reliable transport layer.  SGCP
meets with a hostile reception in SG 16 and TIPHON because of its
centralizing architecture, which differs subtly from that of H.323.

May 1998: A cluster of activity around the issue of control of VoIP gateways
where SS7 is terminated on separate signalling gateways (to conserve point
codes).  Nortel is proposing the use of an extension of DIAMETER, a protocol
under development at the IETF, to do device control.  Ascend and Bay have
extensions to Q.931 for the purpose, which they eventually rationalize into
a single protocol proposal.

May 1998: Level 3 announces the formation of a multi-company Technical
Advisory Committee to work on an IP Device Control protocol (IPDC).  The TAC
is presented with a 100-page specification previously developed by Ascend
and XCOM as their starting point.  Other companies have in-house protocols,
and SGCP is also considered, but the TAC ends up using a modified IPDC over
a DIAMETER base.  IPDC includes the important concepts of event packages and

June 1998: The TAC presents their list of requirements to the H.323
Rapporteurs' meeting in Cannes.  Intel presents an abstract proposal for
H.323 gateway decomposition.  Bellcore presents SGCP.  Work on gateway
decomposition does get started, despite initial hostility and suspicion.  A
TIPHON meeting around this time at least became familiar with the topic.

August 1998: the Level 3 TAC concludes its work and presents a first draft
of IPDC to the IETF and SG 16.  All the discussion of SS7 gateways and
remote control of VoIP gateways culminates in a Birds of Feather (BOF)
session at the IETF.  Out of that eventually comes the decision to form two
working groups: SIGTRAN (transport of SCN signalling over IP) and MEGACO
(Media Gateway Control).  That decision doesn't come until December, but in
the meantime there is active discussion of issues on the IETF lists.  TIPHON
adds gateway decomposition to its architecture, but is having trouble
getting a firm view of that architecture.

September 1998: SG 16 considers gateway decomposition and commits itself to
working on the topic.  Terms of reference are drawn up, along with a
reworking of architectural views initially drawn up in June.  Bellcore  and
Level 3 announce a merger of SGCP and IPDC into MGCP.  The latter is mostly
SGCP with the addition of event packages and termination wildcarding syntax.

November 1998: TIPHON architectural views are settling down.  Lucent brings
in MDCP (Media Device Control Protocol) as a hand-written draft to the SG 16
Rapporteurs' meeting in Torino.  This is completely different from MGCP,
particularly in its connection model.

December 1998: first meeting of the Megaco working group at the IETF.  A
first draft of a requirements document comes out shortly thereafter.

March 1998: a bitter debate over connection model at the Monterey
Rapporteurs' meeting.  In a procedure unusual for SG 16, the MDCP connection
model is chosen via an indicative poll.

April 1998: compromise reached at last on the connection model, at the IETF.
The new model accommodates all of the additional requirements which have
arisen beyond the original design premises of SGCP, and improves on both the
SGCP/MGCP and MDCP models.

May 1998: formal Megaco/H.GCP cooperative arrangement announced.

> -----Original Message-----
> From: Derks, Frank [SMTP:F.Derks at PBC.BE.PHILIPS.COM]
> Sent: Wednesday, June 30, 1999 6:24 AM
> Subject:      Re: MGCP reference (was Re: Megaco/H.gcp conference call)
> HI Nancy,
> maybe it is a good idea to post the history of all these protocols and
> their
> relations (if any) to this list?
> Frank
> -----Original Message-----
> From: Nancy-M Greene [mailto:ngreene at NORTELNETWORKS.COM]
> Sent: 29 June 1999 21:34
> Subject: Re: MGCP reference (was Re: Megaco/H.gcp conference call)
> Chip, you are right, the name Telcordia/Level 3/RSL COM/Vertical MGCP is
> not
> convenient. Christian has already made the same comment you have. I said
> in
> reply to him, and to the list, that I did make an error in adding Cisco to
> the qualifier for MGCP. Since then, I refer to the new Megaco protocol as
> the Megaco protocol, or the Megaco/H.gcp protocol, and to MGCP as MGCP.
> Since a new version of MGCP has come out, version 1,
> (draft-huitema-megaco-mgcp-v1-00.txt), this distinction is even more
> necessary. It makes sense that megaco is part of the file name, because
> there are parts of MGCP that still need to be turned into RFCs for
> packages
> for the Megaco/H.gcp protocol, but it means the new Megaco/H.gcp protocol
> can never really be called MGCP - it is too confusing. It would be good at
> some point to pull the packages out of MGCP to stand alone as a separate
> document for Megaco. And perhaps the UDP + timers part of MGCP so that it
> can stand beside TUDP, MDTP, and TCP as alternatives for Megaco transport.
> Nancy
> --------------------------------------------------------------------------
> Nancy M. Greene
> Internet & Service Provider Networks, Nortel Networks
> T:514-271-7221 (internal:ESN853-1077) E:ngreene at
> > ----------
> > From:         Chip Sharp[SMTP:chsharp at]
> > Sent:         Tuesday, June 29, 1999 2:53 PM
> > To:   Greene, Nancy-M [CAR:5N10:EXCH]; ITU-SG16 at;
> > megaco at
> > Subject:      MGCP reference (was Re: Megaco/H.gcp conference call)
> >
> > Once or twice is a mistake.  When the mistake is continually repeated I
> > wonder...
> >
> > Cisco is NOT an author of MGCP.  Referring to MGCP as
> > "Telcordia/Cisco MGCP" denigrates the hard work of the many people that
> > actually did author the draft as well as the many people and companies
> > that
> > contributed.
> > Maybe it isn't convenient to call it Telcordia/Level 3/RSL COM/Vertical/
> > MGCP?
> >
> > Chip
> >
> > At 06:44 PM 6/16/99 -0400, Nancy-M Greene wrote:
> > ...snip...
> > >mechanism. We need to choose one. There are two proposals on the table:
> > >1) the UDP + timers method in the Telcordia/Cisco MGCP  -
> > >draft-huitema-megaco-mgcp-v0r1-05.txt, and
> > ...snip...
> > --------------------------------------------------
> > Chip Sharp                 voice: +1 (919) 851-2085
> > Cisco Systems              Consulting Eng. - Telco
> > Reality - Love it or Leave it.
> > --------------------------------------------------
> >

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