Re: Netmeeting Videoconferencing

[Mark Brown <broonie () sirena org uk>]

On Fri, Jul 13, 2001 at 10:03:17AM +0200, Patrick M. Hausen wrote:

> While Gauntlet provides a "netmeeting proxy" which is
> just a transparent TCP plug for a particular port, I
> think I remember Netmeeting using H.323 for audio/video.

> If this is indeed the case (can someone confirm?), I'm

Yes, NetMeeting does use H.323 for this.  I believe it also implements a
number of other things that you might want to look at like desktop
sharing.

> data stream. And port numbers are selected dynamically
> in the same way ISDN devices pick TEIs - what a
> brain damaged protocol. :-(

That was kind of a design goal, I believe :-) .  There does tend to be a
degree of predictability in the ports which a given H.323 implementation
will choose to use but I wouldn't want to rely on it.

> Are there any open source H.323 proxies? I found some
> "gatekeeper" software, but according to my understanding
> gatekeepers only manage call setup. The audio/video

You're probably going to need to use a gatekeeper anyway so that the
systems can find each other and so you can authenticate, particularly if
you're trying to talk over disjoint networks in private IP space.

> packets are exchanged directly between the two parties
> taking part in a call for delay reasons.

Generally, yes.  However, part of the role of the gatekeeper is to
provide additional services to endpoints that they do not implement for
themselves.  In order to allow it to do this the gatekeeper is able to
intercept and rewrite all the call signalling messages.  This allows
them to do things like talk to firewalls and get them to open/close
ports as and when needed or rewrite messages to redirect traffic in a
manner that will get through a firewall (including pointing at a proxy).  

These things are all likely to need programming, though.

The main free H.323 implementation I'm aware of is OpenH.323
(http://www.openh323.org) - someone mentioned a proxy derived from it.

-- 
"You grabbed my hand and we fell into it, like a daydream - or a fever."
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