MAC address confusion

Date: Tue, 3 Mar 2009 08:42:16 +0200
From: Saku Ytti <saku+nanog@ytti.fi>

> > > > http://standards.ieee.org/regauth/oui/oui.txt
> > > > 02-07-01 (hex) RACAL-DATACOM
  
> > Would be interesting to see what are the historical reasons.Perhaps they simply
> > predate the scheme or some might not even co-exist in ethernet network to begin
> > with, in which case they might be better documented elsewhere.
>
> IEEE after 802.3 was ratified. IEEE agreed to retain existing
> registrations and they have remained there.

So where does this leave the current local scape addresses being globally
assigned? Is it possible that we will run into legit 02 MAC addresses
in the wild?

Thee are properly "locally assigned",not "local scope" addresses, but
the effect is the same.

This is only a problem if you have multiple systems running DECnet (or
some other protocol using this) with the same layer 3 address. That
should never happen, so there should be no duplication.

The only real issue I see is with IPv6 EUI-64 addresses and even in that
case, there would have to be two systems getting their address space
from the same router interface before there is a conflict.

Why would they need to have same L3 address? The way I see it, only thing that
matters is, if or not, the addresses might speak ethernetII. If your ethernetII
switch sees your local 02 address and one of the addresses below and they
collide, the switch will keep relearning the address behind two ports. Unless
of course it is guaranteed, that none of these addresses will ever appear as
BIA in ethernetII capable NIC.

02-07-01 (hex) RACAL-DATACOM
02-1C-7C (hex) PERQ SYSTEMS CORPORATION
02-60-86 (hex) LOGIC REPLACEMENT TECH. LTD.
02-60-8C (hex) 3COM CORPORATION
02-70-01 (hex) RACAL-DATACOM
02-70-B0 (hex) M/A-COM INC. COMPANIES
02-70-B3 (hex) DATA RECALL LTD
02-9D-8E (hex) CARDIAC RECORDERS INC.
02-AA-3C (hex) OLIVETTI TELECOMM SPA (OLTECO)
02-BB-01 (hex) OCTOTHORPE CORP.
02-C0-8C (hex) 3COM CORPORATION
02-CF-1C (hex) COMMUNICATION MACHINERY CORP.
02-E6-D3 (hex) NIXDORF COMPUTER CORPORATION