Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!sdd.hp.com!elroy.jpl.nasa.gov!decwrl!uunet!mcsun!cernvax!chx400!urz.unibas.ch!doelz
From: doelz@urz.unibas.ch
Newsgroups: comp.sys.dec
Subject: Re: DECNET MAC address use query
Message-ID: <1990Nov13.092246.1172@urz.unibas.ch>
Date: 13 Nov 90 08:22:46 GMT
References: <1990Nov8.125106.18326@gdr.bath.ac.uk> <12925@blia.BLI.COM> <1990Nov12.155501.23342@gdr.bath.ac.uk>
Organization: University of Basel, Switzerland
Lines: 28

In article <1990Nov12.155501.23342@gdr.bath.ac.uk>, exspes@gdr.bath.ac.uk (P E Smee) writes:
> 
> How about the following as a closer guess?  We are running a number of
> DEC machines with hardware MAC addresses of 08-00-2b-... (and a Silicon
> Graphics box 08-00-69-...).  We are told that when they start wanting
> to use DECnet across our bridges, we will have to tell the bridges that
> their addresses are AA-00-04-<something else>.  It appears that this
> latter address holds when they are running DECNET protocol; and we
> believe that they will still continue to claim to be 08-00-2b-whatever
> when they are running other protocols.  Is this any better?  (Still
> means that from the point of view of the bridge, the box has two
> addresses.)

Still wrong. As soon as any machine boots decnet, the (hardwired) board 
address will be reconfigured to read aa:00:... :node:area - and there is 
no 08:00: .. any longer. If you want to gain the old addresses back, the 
decnet must be shut down, and the hardware rebooted.  However, the appletalk 
will also run on aa:00... addresses, because its a different layer! The 
layer we are currently talking about is so low that there is no need 
to know which protocol is running... its decoded much higher in the hierarchy
of OSI layers. There is a protocol code for that in each packet, and the 
hardware takes care of that... 


Reinhard 

(The above saying applies to: VAX, SGI, CONVEX, MAC, and I have reasons to 
believe that other machines behave similar)