On Sat, 22 Apr 2000, der Mouse wrote:

> >>> I assume ab:0:0:1:0:0 is a broadcast address?
> >> I *think* there's only one broadcast Ethernet address,
> >> ff:ff:ff:ff:ff:ff.  ab:0:0:1:0:0 is a multicast address, used for
> >> just this sort of MOP booting.
> > Well, no.  Multicast is an IP term.
> 
> Certainly.  But it's also an Ethernet term.

Had to look it up, but you're right. Oh well, I was a bit fast there...

> > In ethernet, all addresses with a "1" in the low bit of the first
> > byte is a broadcast, since that is the broadcast bit.
> 
> Actually, in Ethernet all packets are broadcast to all nodes, and it's
> up to the hosts and/or their hardware what packets to "received", that
> is, to capture as they go by on the wire and kick upstairs to the host.

Well, yes, since ethernet is a multiple access medium. :-)

> The hardware/firmware in normal Ethernet interfaces receives packets
> sent to all-ones and packets sent to its own ("unicast") address.

Not neccesarily. The DELUA for instance don't think ff:ff:ff:ff:ff:ff is
any different from 01:00:00:00:00. You have to program it to receive
either of them. The only address it by default receives on is its own
address.

> Non-all-ones packets whose first address bit is one are called
> multicast, and most (all?) hardware has special provisions for
> configuring the reception of such packets....

Yup. But like I said, some of them don't treat all ones any special. There
is really no good reason to do so either.
But from an abstract point of view, there might be a point of separating
the two.

	Johnny

Johnny Billquist                  || "I'm on a bus
                                  ||  on a psychedelic trip
email: bqt@update.uu.se           ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol