Hi --

I'm new to the list though I have been on IRC now & then.  

I loved Jacobson's talk but one point struck me: the introduction of a new
paradigm doesn't obviate the need for the old.  Packet-switching is great
for fault-tolerance when the goal is "get this packet from here to there, no
matter what."   It's actually the postal paradigm (thru wind & sleet...)

But the old telco real-time, hard-wired point-to-point connection was
actually better suited to some things we do today over packet networks,
particularly teleconferencing.  The control over latency and timing is lost
when you switch to TCP (as you VOS folks know only too well).

A data subscription model is really just a cool technological way to
introduce the concept of publishing to the digital world in a useful way;
but it doesn't change the fact that packet-switched networks are not so
great for realtime communication.

WRT VOS/Interreality goals, in particular avatar/object behavior (whether
scripted or resulting from user input), we have a mix of requirements that
doesn't easily fit any model I'm aware of.  It's time critical, like a phone
conversation; it's point-to-many-point, like publishing; it's ephemeral,
like broadcasting; but it's not fully global, in that typically you only
care about a few objects in your virtual vicinity.  Distributing this data
liberally is not an option due to bandwidth.

The bittorrent model doesn't really wash here because of the requirement for
low latenc.  I think in this case we have another animal entirely, which is
basically a secure multipoint channel cluster.  The closest analogy I'm
aware of would be multi-party teleconferencing.  AT&T actually does this
pretty well.

This animal should be optimized for its intended use, and not shoe-horned
into paradigms that it doesn't really fit.  It might be reasonable to take a
look at some of the ITU work in this area, such as H.323, and even the IETF
VOIP/SIP stuff that's out there.  

I'm not saying we should necessarily adopt any such standards; but it is
often worthwhile to take a good look at how similar problems have been
tackled, for better or worse.  Otherwise you risk spending mucho time
reinventing various types of wheels.

-dbm


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