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From: oberman@rogue.llnl.gov
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Reply to Ethernet Address Uniqueness...
Message-ID: <1990Oct5.120922.1@rogue.llnl.gov>
Date: 5 Oct 90 19:09:22 GMT
References: <5A0A050B012801FE-MTAEMR1*fillmore@emrcan>
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In article <5A0A050B012801FE-MTAEMR1*fillmore@emrcan>, fillmore@emrcan.BITNET writes:
> In the DEC VAX environment the unique Ethernet address on each board is
> overridden by DECNET when it starts to use that board.  The address is set
> to four bytes of a constant value plus two bytes which contain the DECNET
> area and node numbers.  Lots of opportunity for duplication!
> Does anyone know why DEC chose this scheme?
 
Basic answer- They messed up! DECnet Phase V will abandon this ill concieved
idea. It was a clever idea to allow a direct and unambiguous translation from
DECnet address to Ehternet address which eliminates the need for ARP or some
similar method of Ethernet address resolution. They have since learned the
folly of this and do the reverse in Phase V. They code the 6 bytes of the
Ethernet address into the system's NSAP (OSI address).

					R. Kevin Oberman
					Lawrence Livermore National Laboratory
					Internet: oberman@icdc.llnl.gov
   					(415) 422-6955

Disclaimer: Don't take this too seriously. I just like to improve my typing
and probably don't really know anything useful about anything.