On Apr 8,  6:46pm, Wolfgang Solfrank wrote:
} Subject: Re: Znyx multi channel ethernet cards
} > 'cause its illegal...each device on each net must have a globally
} > unique address. The fact that you can make it work is irrelevent.

Actually, if you're speaking DECnet, it's required.  Since DECnet Phase IV 
doesn't have the equivalent of ARP, DECnet speaking nodes reprogram the
their Ethernet addresses based on their DECnet Area and Node numbers.
>From my archive of networking trivia:

   The Ethernet address may be calculated by the formula of (Area*1024) + Node.
   These 2 bytes are swapped and used as the last 2 bytes of the address. The
   first 4 are always AA-00-04-00.

} No, it's not.  Conceptually, ethernet addresses are per machine, not per
} interface, contrary to e.g. IP-addresses.
} 
} Only people building ethernet interfaces for machines that don't have a
} unique id themselves (like the pc) have to assign an ethernet address per
} interface as it resides in a rom on the card.

Since Sun's use of the same address on multiple interfaces has been
mentioned, here's what the Sun Managers FAQ (which quotes the Ethernet
spec) has to say:

Subject: 12.1)   Why do both my net interfaces have the same ethernet address?

  The Ethernet version 2.0 specification (November 1982) states:

          The physical address of each station is set by network
          management to a unique value associated with the station,
          and distinct from the address of any other station on any
          Ethernet.  The setting of the station's physical address
          by network management allows multiple multiple data link
          controllers connected to a single station to respond to
          the same physical address.

  This doesn't normally constitute a problem because each interface will
  typically be on a different subnet. If, for some reason, different
  ethernet addresses are required on different interfaces (for example, to
  attach two interfaces to the same subnet), a new one may be assigned
  using the ifconfig command.

I guess you could blame the Ethernet designers for not anticipating the
desire to plug multiple interfaces into the same Ethernet switch ...

			---  Truck