Subject: RE: Any comparison Study on MGCP vs H.323, MGCP vs SIP

From: Christian Huitema <[email-masked]>
Date: Fri, 12 May 2000 14:55:58 -0700

From the SGCP FAQ (http://www.argreenhouse.com/sgcp/sgcp-faq.shtml) written
two years ago:

	Do you intend to replace H.323 ? 
Definitely not. Just look at the picture above, which shows the relaying of
a call 
between an SGCP controlled gateway and an H.323 agent. The combination of
gateways plus call agent forms a distributed H.323 system, which is
perfectly conforming to the H.323 standard...
	If not H.323, why not SIP, then? 
In fact, when we realized that we could not use H.323 between the call agent
and the gateways, we tried to base the design of SGCP on SIP. But we
stumbled on the fact that SIP is a peer to peer protocol, while we needed a
master slave protocol. However, interworking between SIP and SGCP is very
easy...

(SGCP is one of the ancestors of MGCP.)

-- Christian Huitema

> -----Original Message-----
> From: Yixin Zhu [mailto:[email-masked]]
> Sent: Thursday, May 11, 2000 7:55 AM
> To: [email-masked]
> Subject: Any comparison Study on MGCP vs H.323, MGCP vs SIP
> 
> 
> Hi,
> 
> There are studies on the comparision of the two competing 
> protocol SIP and
> H.323. However, MGCP can also provide call control functionalities. A
> network with MGCP only (Call agent, MG etc) can provide basic 
> VoIP service
> too. Then my questions are
> 
> 1. Are there any comparison study between MGCP and H.323?
> 
> 2. Are there any comparision study between MGCP  and SIP?
> 
> 
> You help is very much appreciated. Thanks,
> 
> 
> Yixin (James) ZHU
> 
>

---

From: Masataka Ohta <[email-masked]>
Date: Sat, 13 May 2000 09:19:55 +0859 ()

Christian;

> master slave protocol. However, interworking between SIP and SGCP is very

Technical comparisons are irrelevant.

For VoIP over telephony networks (that is, mostly over non-Internet
networks), H.323 and SS7 are the protocols to choose, because they
are defined by ITU-T.

As I pointed it out with regard to iMODE and WAP, an attempt to promote
protocols like SIP, a NAT friendly protocol even more complex than
H.323, was based on a wrong strategy destroying the Internet into a
collection of mostly-non-IP networks connected by application/transport
gateways with mostly-non-IETF application/transport protocols.

For IETF (IETF is for Internet not IP) style VoIP, that is, Internet
telephony, SGCP, MGCP, H.323 and SIP are all wrong that it is a waste
of mailing list bandwidth to compare them.

This mail of mine is not an exception, unless I make the following
advertisement:

	If you are interested in Internet telephony, see you at
	INET'2000 in Yokohama for the presentation of our paper
	"The Simple Internet Phone".

;-)

							Masataka Ohta

---

From: Harald Tveit Alvestrand <[email-masked]>
Date: Sat, 13 May 2000 23:27:10 +0200

>networks), H.323 and SS7 are the protocols to choose, because they
H.323 is defined for a LAN environment, not for telephone lines.
SS7 is not a protocol accessible to the subscriber.

If you want to use ITU protocols, please choose some other numbers.

                  Harald

--
Harald Tveit Alvestrand, EDB Maxware, Norway
[email-masked]

---

From: Masataka Ohta <[email-masked]>
Date: Sun, 14 May 2000 08:32:44 +0859 ()

Harald;

> H.323 is defined for a LAN environment, not for telephone lines.

For telephony people, the IP protocol is for a LAN environment
that there is no difference between H.323, SIP, TELNET, or DNS
for that matter.

> SS7 is not a protocol accessible to the subscriber.

So?

As I said:

> >For VoIP over telephony networks

some protocol is necessary between two telephony networks.

FYI, there is a protocol called TBGP proposed in IETF for the purpose.

> If you want to use ITU protocols, please choose some other numbers.

So, you are saying SGCP/MGCP are wrong to use 323.

Fine.

FYI, in my design of "The Simple Internet Phone":

I chose to keep using 164 (sorry, not 42) at least for the time being,
because it is the easiest way to let subscribers replace telephony
network with the Internet.

							Masataka Ohta

---

From: "Stephen Sprunk" <[email-masked]>
Date: Mon, 15 May 2000 12:35:56 -0500

Sez "Masataka Ohta" <[email-masked]>
> that there is no difference between H.323, SIP, TELNET, or DNS

"Telephony people" are not relevant here, since we're talking about
VoIP.

> > >For VoIP over telephony networks

Your statements don't make sense; "VoIP over telephony networks" is an
oxymoron, since VoIP is, by definition, over an IP network.

> FYI, there is a protocol called TBGP proposed in IETF for the purpose.

TBGP is the proposed method for binding E.164 numbers to telephony
domains, much like DNS binds names to IP addresses.  One would still use
SIP (or equivalent) to actually complete the call.

> So, you are saying SGCP/MGCP are wrong to use 323.

No, he's suggesting that if you wish to use an ITU protocol, H.323 is
not the correct one.  Perhaps Q.931?

> "The Simple Internet Phone".

Please let us know the URL where you'll be publishing this paper, as
some of us may not be inclined to fly to Yokohama to hear about yet
another non-standard, proprietary telephony protocol.

> network with the Internet.

MGCP/SGCP/Megaco directly use E.164 numbers.  SIP allows users to see
only E.164 numbers during a transition period, though it becomes much
more pwoerful when you move to a more expressive namespace.

[from a prior message]
> As I pointed it out with regard to iMODE and WAP, an attempt to
> promote protocols like SIP, a NAT friendly protocol even more
> complex than H.323

SIP may or may not be NAT-friendly, a point which is best left to other
(time-wasting) threads.  I would love to see any explanation of how SIP
is more complex than H.323; maybe you have them backwards?

> was based on a wrong strategy destroying
> the Internet into a collection of mostly-non-IP networks connected
> by application/transport gateways with mostly-non-IETF
> application/transport protocols.

SIP is not, as you state, based on a strategy of building non-IP
networks and connecting them with non-IETF protocols; in fact, it's
quite the opposite.  SIP allows the replacement of non-IP (ie. legacy
telephony) networks and non-IETF (ie. ITU) protocols; in the ideal SIP
world, legacy telephony would cease to exist.

While a bit dated, Henning Schulzrinne and Jonathan Rosenberg's paper
has quite a bit of detail on the subject:
http://www.cs.columbia.edu/~hgs/papers/Schu9807_Comparison.ps.gz

> Masataka Ohta

S

     |          |         Stephen Sprunk, K5SSS, CCIE #3723
    :|:        :|:        Network Consulting Engineer, NSA
   :|||:      :|||:       14875 Landmark Blvd #400; Dallas, TX
.:|||||||:..:|||||||:.    Email: [email-masked]

---

From: Masataka Ohta <[email-masked]>
Date: Tue, 16 May 2000 06:15:22 +0859 ()

Stephen Sprunk;

I dare reply because your mail demonstrates common misunderstandings
by people outside of the Internet.

> "Telephony people" are not relevant here, since we're talking about

Huh?

> oxymoron, since VoIP is, by definition, over an IP network.

Some IP networks are pure telephony networks.

Only one IP network in the world is the Internet.

> not the correct one.  Perhaps Q.931?

He is not saying anything meaningful.

> MGCP/SGCP/Megaco directly use E.164 numbers.  SIP allows users to see

The context is that Yixin said something about S/MGCP and 323 and
Chrisitian acknowledged. I know the relevance is meaningless.

> another non-standard, proprietary telephony protocol.

You seem to have no knowledge on INET and IETF.

Signature of Vint will be a good starter for you.

Or, ask someone who knows something about not only IP networks but
also the Internet.

> world, legacy telephony would cease to exist.

We, IETF, are for the Internet, not merely IP.

							Masataka Ohta

---

From: Dhaval Shah <[email-masked]>
Date: Mon, 15 May 2000 14:38:40 -0700 (PDT)

Hi,

> > FYI, there is a protocol called TBGP proposed in IETF for the purpose.

Just a minor correction. The new name for this protocol is TRIP.

Thanx,
Dhaval