Subject: Advantages of SIP over H.323

From: Kaya Bekiroglu <[email-masked]>
Date: Tue, 16 Sep 1997 09:49:45 -0700

I don't want to start a holy war on this list, but I was wondering if
someone has summarized the compelling advantages of SIP over H.323 (if
any) and where I could find such a document.  

Kaya Bekiroglu
Program Manager, TAPI 3.0
Windows NT Networking Group
Microsoft

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From: Peter Hoermann <[email-masked]>
Date: Wed, 17 Sep 1997 12:40:14 +0200

> any) and where I could find such a document.

Hi Kaya,

H.323 embraces lots of standards; comparable with SIP in the MBone
protocol stack are - IMO - H.225.0 (especially Q.931 (call controlling
like SETUP etc.)) and H.245.

But it seems to me that the H.323 people asked themselves already if it
was enough to just initiate a session (like SIP does) and then leave the
rest to the terminals (like it's done by vat, rat and vic in MBone); as
far as I know they call it 'fast call setup' or so and it resembles a
direct invitation (INVITE) with the option (!) to set up a H.245
channel. 

But why not ? As you know RTP always comes with RTCP and there is (at
least a little) control you can work with; I already wondered if the
existing products of the H.323 area are exploiting the RTCP messages
(e.g. for stream control) or aren't they even sending RTCP messages ?

Comments (maybe I'm totally wrong ;-) and hints would be appreciated.

Peter

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From: Henning Schulzrinne <[email-masked]>
Date: Wed, 17 Sep 1997 16:47:47 -0400

I have tried to update my SIP FAQ page at
http://www.cs.columbia.edu/~hgs/sip/faq.html to address this issue.
Since H.323 is somewhat of a moving target, I have taken the approach of
comparing today's H.323 with the current SIP spec. I'm sure I got some
of the H.323 details wrong, so I'd appreciate corrections and additions.