Subject: MGCP/Megaco differences - was RE: MGCP/MEGACO for broadband servi ces

From: Nancy-M Greene <[email-masked]>
Date: Thu, 23 Sep 1999 09:48:30 -0500

Here is my summary of the differences, as well as a pdf file with a table
comparing the two. The table is something I produced in March, 1999 when we
were comparing predecessors to the Megaco protocol. I have updated it to
compare Megaco and MGCP.

Please send me any comments!

 <<MegacovsMGCPv1.pdf>>
References:
[1] F. Cuervo, B. Hill, N. Greene, C. Huitema, A. Rayhan, B. Rosen, J.
Segers, "Media Gateway control protocol (Megaco/H.248)", Working Document of
the IETF Megaco WG, <draft-ietf-megaco-protocol-04.txt> (or
ftp://standards.nortelnetworks.com/megaco/docs/latest/megaco-h248_protocol.p
df  ), Sept 1999
[2] M. Arango, A. Dugan, I. Elliott, C. Huitema, S. Pickett, "MGCP 0.1",
<draft-huitema-megaco-mgcp-v0r1-05.txt>, May 1999
[3] M. Arango, A. Dugan, I. Elliott, C. Huitema, S. Pickett, "MGCP 1.0",
<draft-huitema-megaco-mgcp-v1-02.txt>, August 1999

Note that <draft-ietf-megaco-protocol-04.txt> will be available later this
week - it will be a full text-only version of the Megaco/H.248 protocol. It
will be identical to the pdf file already available at
ftp://standards.nortelnetworks.com/megaco/docs/latest/megaco-h248_protocol.p
df

I have also put the comparison tables attached here on the above ftp site.

Main Differences between Megaco/H.248 and MGCP
---------------------------------------------------------------------------
1) transactions
- Megaco/H.248 uses transactions to group together commands. Command
responses and errors are clearly marked in the transaction reply.

- MGCP uses command embedding, and it is not easy to find the individual
responses to embedded commands.

2) multimedia
- Megaco/H.248 is multimedia ready - it has a defined way to set mixing
parameters for video, audio - default is audio mixing of all terminations in
a context.
- although MGCP uses sdp, it does not have any capability to set mixing
parameters for video, for example. Thus it is not as multimedia ready as
Megaco/H.248.

3) moving a termination/endpoint from one "call" to another
- in Megaco/H.248 you use Move to move a termination from one context to
another. Useful for call waiting, 3-way calls.

- MGCP v0r1-05 does not have a Move command - the newest MGCP v1 does have a
Move command.

4)  Packages
- An Internet-Draft of Megaco/H.248 generic packages for lineside and
trunking will be published in a week. They draw heavily from MGCP, but
should be clearer to use and more complete. They will be published
separately from the Megaco/H.248 base protocol, with registration to be done
through IANA, and with version numbers. (In the IETF, they will be in
separater RFCs, and in the ITU-T SG16, they will be annexes to H.248). New
packages not in MGCP are also being defined - i.e. for R2, for IP Phone, as
well as a standard way to register new packages and updates to existing
packages.

- MGCP packages are bundled into the MGCP document. Not easy to evolve them,
nor update them, nor no standardized way to register them.

5) Call Model
- Megaco/H.248 has a more general call model than MGCP - thus more
efficient for TDM to TDM calls, TDM to ATM calls, etc., as well as still
working well for TDM to IP calls.

6) Multiplexing
- the Megaco/H.248 protocol supports multiplexing, while MGCP does not.

7) Authentication Header
- the Megaco/H.248 protocol includes an authentication header that
providessecurity when IPSEC is not available.

- MGCP does not have this.

8) failover
- Megaco/H.248 allows the MGC to provide a new MGC the MG should communicate
with in the ServiceChange command.

- MGCP does allow the MGC to send a new MGC to contact to the MG - it is
piggybacked on certain commands.

Nancy
--------------------------------------------------------------------------
Nancy M. Greene
Internet & Service Provider Networks, Nortel Networks
T:514-271-7221 (internal:ESN853-1077) E:[email-masked]

> ----------
> From:         Arik Klein[SMTP:[email-masked]]
> Sent:         Thursday, September 23, 1999 2:09 AM
> To:   [email-masked]
> Subject:      MGCP/MEGACO for broadband services
>
> As I understand, the current MGCP/MEGACO protocol is mostly VOICE services
> oriented.
> Could anyone say if, and from which version, the MGCP protocol inteds to
> support DATA services,
> such as:   IPoA, MPLS, IP-VPN, video delivery services and other broadband
> services ?
> What are the main shortcomings in the protocol regarding those issues ?
>
> Could you also help me understand the differences (if any) between the
> MGCP
> and the MEGACO work, and what
> is currently available ?
>
> Best Regards,
> Arik Klein
>