Jim Henderson wrote:
> Assuming the switch isn't multicast aware.  I wouldn't be surprised if 
> some were these days (but I haven't looked at it recently).

Um, no. Even so.

If you have one cable coming into the university campus, and a network for 
each building, the router is going to have to send the packets to each 
building, duplicating the packets, regardless of how "aware" anyone is.

> It's more like multiple people listening to a radio station - the data is 
> only transmitted once per subnet.

Right. But you have to duplicate it for each subnet, which is the "party 
line" equivalent.

> The difference between, for example, 
> using unicast to push an image down to 15 workstations on a subnet and 
> using multicast to push an image down to 15 workstations on a subnet is a 
> significant reduction in overall network traffic.

Only for that one subnet.

It's better than a unicast stream to each destination, yes. That doesn't 
mean IP isn't point-to-point, if you factor in the broadcast address as 
meaning "one subnet is the point."

-- 
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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