Path: utzoo!attcan!uunet!samsung!usc!orion.oac.uci.edu!draco.acs.uci.edu!iglesias
From: iglesias@draco.acs.uci.edu (Mike Iglesias)
Newsgroups: comp.sys.dec
Subject: Re: DECNET MAC address use query
Message-ID: <273F4A7D.27274@orion.oac.uci.edu>
Date: 13 Nov 90 01:21:01 GMT
References: <1990Nov8.125106.18326@gdr.bath.ac.uk> <12925@blia.BLI.COM> <1990Nov12.155501.23342@gdr.bath.ac.uk>
Reply-To: Mike Iglesias <iglesias@draco.acs.uci.edu>
Organization: University of California, Irvine
Lines: 40
Nntp-Posting-Host: draco.acs.uci.edu

In article <1990Nov12.155501.23342@gdr.bath.ac.uk> P.Smee@bristol.ac.uk (Paul Smee) writes:
>In article <12925@blia.BLI.COM> ted@blia.BLI.COM (Ted Marshall) writes:
>>The station address is set as follows: The first 4 bytes are AA-00-04-00.
>>The last two bytes are computed as (area * 1024 + node), byte swapped.
>>Thus, DECnet address 8.56 would compute as (8 * 1024 + 56) = 8248 = 0x2038.
>>Thus, the corresponding Ethernet address would be AA-00-04-00-38-20.
>
>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.)

No, they will use the AA-00-04 address for TCP/IP, etc.  If the bridge
learns addresses by looking at the net, you shouldn't have any problems.
If you have to tell your bridge what system is on each side of the bridge,
they you need to tell it the AA-00-04 address, not the 08-00-2B address
(assuming you're running DECNET).  You also have to start DECNET before
any other protocol so the other protocols get the right ethernet address.
This is true for VMS and Ultrix.  Otherwise, you may confuse other systems 
on the network!

>We also hear rumours that AA-00-04-... machines may under some
>circumstances use AA-00-03-<same thing>.  (AA-00-03-... is registered
>as 'Global physical address for some DEC machines' -- or, in other
>words, is assigned to DEC.)

I've never seen this - maybe a DEC expert knows?


Mike Iglesias
University of California, Irvine
Internet:    iglesias@draco.acs.uci.edu
BITNET:      iglesias@uci
uucp:        ...!ucbvax!ucivax!iglesias