Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!ukc!dcl-cs!gdt!exspes
From: exspes@gdr.bath.ac.uk (P E Smee)
Newsgroups: comp.sys.dec
Subject: Re: DECNET MAC address use query
Message-ID: <1990Nov14.100319.27782@gdr.bath.ac.uk>
Date: 14 Nov 90 10:03:19 GMT
References: <1990Nov13.025835.759@spcvxb.spc.edu>
Reply-To: P.Smee@bristol.ac.uk (Paul Smee)
Organization: University of Bristol c/o University of Bath
Lines: 32

In article <1990Nov13.025835.759@spcvxb.spc.edu> terry@spcvxb.spc.edu (Terry Kennedy, Operations Mgr) writes:
>  AA-00-03-... is the hardware address on the older DEC interfaces, such as
>the DEUNA. It is changed to AA-00-04-... when DECnet is started, just as on
>the other boards. I don't know why DEC changed to 08-00-2B-... when they came
>out with the newer interfaces. Perhaps people were being confused by the -03-
>vs. -04-?

Thanks everyone who responded, that's been a great help.  Reason for
picking on this one to 'F' to is the question of the 'change to
08-00-2B-...'  Our copy of the IEEE assignments list mentions that one
of the bits in AA- is the 'locally administered' bit, which means that
in general any site can nick an AA-... address for locally produced
stuff which has not been given a company registration.

(Of course, if you are clever and know about existing uses you will not
use AA-00-03-... (or -04-...), but if you were working from the
protocol description alone, without a list of assigned manufacturers'
address ranges, you could accidentally end up assigning a home-brew
device to an address which would match one of the addresses being used
by DEC.  Murphy's law says that you would then order a box from DEC and
end up on the same number.)

Or, in other words and basically, 08-00-2B-... is ASSIGNED to DEC.  The
two AA- addresses are listed as DEC because DEC nabbed them before
things were properly organised.  In theory, 'locally administered'
addresses shouldn't be used for any equipment which might be connected
to anything which is NOT on your site, which means that according to
modern theology, they shouldn't be used by vendors.

-- 
Paul Smee, Computing Service, University of Bristol, Bristol BS8 1UD, UK
 P.Smee@bristol.ac.uk - ..!uunet!ukc!bsmail!p.smee - Tel +44 272 303132