All things related to multicast

[Hugh LaMaster <>]

On Thu, 13 May 2004, Greg Shepherd wrote:

> Conferencing has been repeatedly miss-identified as an "ideal" multicast
> application. It is not. And acutally, much of the baggage we have today
> with ASM came from that miss-targeted application.
> 
> Greg
> 
> On Thu, 13 May 2004, Bill Owens wrote:
> 
> > On Thu, May 13, 2004 at 04:24:36PM -0400, Richard Mavrogeanes wrote:
> > > My two cents:
> > >
> > > Multicast is not used more often because:
> > >
> > > 1. The default condition of virtually all routers is to disable
      multicast.
> > . . .
> >
> > All true, and I certainly know that multicast is not an easy thing to
    configure, manage and repair (or even understand!) but I'm intentionally
    preaching the choir here. I wasn't asking why Joe Public doesn't use
    multicast more often, I was asking why *we* don't use it more often.
> >
> > My application, weekly recurring conference calls with a standing group
    of people, all at Internet2 sites, all of them advanced network users,
    seems like an ideal place to use multicast a/v tools - and yet, we don't.
    There must be dozens of similar conference calls every week; heck, 
    Internet2 has their own conference system, and they wouldn't have bothered
    if they
    didn't use it a lot. Isn't there something wrong with that picture?

Conferencing isn't the killer app, but, network folks would use it 
if only required a little more effort.  That would at least keep
the infrastructure working.

Im my experience, the biggest impediment to doing conferencing is lack
of echo cancellation in full-duplex mode.  "vat" was amazing for its day,
but, it didn't do echo cancellation in software, and nobody had or has
H/W echo cancellation in their cheap host microphone/speaker setups.
People didn't like "use-mouse-button-to-talk, but, had to.  Now that most
desktops are probably at 360-400MHz CPU or better (maybe 2.4 GHz),
software echo cancellation might work.  A lot of offices have speakerphones,
and conference rooms mostly have decent phone setups.  In other words, 
"It's the audio."


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 Hugh LaMaster, M/S 233-21,   Mail: 

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