🚀 go-pugleaf

In article <1990Nov8.125106.18326@gdr.bath.ac.uk>, exspes@gdr.bath.ac.uk (P E Smee) writes:
> We are told that DEC, rather than assigning a single MAC address to a
> given machine, assigns a group of MAC address to each box, so that the
> DECNET protocol can use some of the 'address' bits to send small
> control messages around.  (I find this distasteful, but apparently it's
> 'legal' as long as they stick to their assigned address range.)

Whomever told you that is dead wrong! A machine running DECnet has its
Ethernet address set based on the DECnet address (see below). Each machine
has a single address only. Multicast addresses in the range AB-00... are
also used but not as station addresses.

The station address is set as follows: The first 4 bytes are AA-00-04-00.
The last two bytes are computed as (area * 1024 + node), byte swapped.
Thus, DECnet address 8.56 would compute as (8 * 1024 + 56) = 8248 = 0x2038.
Thus, the corresponding Ethernet address would be AA-00-04-00-38-20.

Hope this helps.

-- 
Ted Marshall          ...!ucbvax!mtxinu!blia!ted  <or>  ted@blia.bli.com
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The opinions expressed above are those of the poster and not his employer.