MAC address confusion

Tue Mar 3 21:50:33 UTC 2009

> Date: Tue, 3 Mar 2009 08:42:16 +0200
> From: Saku Ytti <saku+nanog at ytti.fi>
> 
> On (2009-03-02 17:31 -0800), Kevin Oberman wrote:
> 
> > > > > 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.
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634
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