Jim Henderson wrote:
> What do you mean by "2-way broadcast"?

Well, FM radio would be a one-way broadcast. Coax ethernet would be a 
two-way broadcast.

> Yes, but from a standpoint of multicast, there again, you get some 
> savings (and increased scalability).  I imagine (but don't know for sure) 
> that cable uses some sort of multicast scheme

Well, look, there really isn't something that's a multicast physical layer. 
Either the bandwidth is scaled per user, or it isn't. If we're all talking 
at the same frequency on a coax cable (say like old ethernet) and I'm 
transmiting, it's a broadcast, regardless of the destination address.

AFAIK, cable systems run fiber to a box in each neighborhood, and then have 
a tree of cables coming out from there, all carrying the same signal.

> all people who are watching channel 657 are likely part of a 
> multicast group of some sort,

Sure. And all people watching channel 657 are also receiving channel 652. 
They're just not tuning it. Just like FM radio.  (And I was talking about IP 
over cable, actually, not TV per se. :-)

-- 
Darren New, San Diego CA, USA (PST)
    Ada - the programming language trying to avoid
    you literally shooting yourself in the foot.

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