Jim Henderson wrote:
> Depends on how the router implements forwarding for multicast - ISTR that 
> some routers can be configured to forward multicast traffic up to a 
> specified TTL, but what's forwarded is still multicast traffic.

Yes. And if you have a router with three ethernet connections plugged into 
it, it's going to duplicate each multicast packet onto each ethernet 
connection. Otherwise it isn't multicast.

The whole multicast protocol is nothing more than telling each router on the 
path which outputs it needs to duplicate packets on to, so you *don't* get 
multicast going onto network segments where nobody is listening for them.

Of course when it's duplicated it's still a multicast packet. That's defined 
by the source address, and on any given segment that supports broadcast it 
is treated as a broadcast packet. It's still point-to-point between routers. 
I.e., it's still point to point if you treat "all the people listening to 
the same broadcast address on the same network segment" as one point of the 
multicast transmission.

-- 
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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