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From: xjeldc@tts.lth.se (Jan Engvald)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Ethernet Address Uniqueness...
Message-ID: <1990Oct19.223146.14613@lth.se>
Date: 19 Oct 90 22:31:46 GMT
References: <5A0A050B012801FE-MTAEMR1*fillmore@emrcan> <1990Oct5.123350.145@arizona.edu> <2126@excelan.COM> <1990Oct19.120616@ria.ccs.uwo.ca>
Sender: newsuser@lth.se (LTH network news server)
Reply-To: xjeldc@ldc.lu.se (Jan Engvald)
Organization: Communication Systems, Lund Institute of Technology, Sweden
Lines: 32

>While DECnet IV wants to change the ethernet number to match the DECnet node
>and host number, IPX only requires the same ethernet number to be used on all
>interfaces to a machine.  It doesn't care what they are set to.  This allows
>DECnet and IPX to  coexist on the same router as long as you get the DECnet
>running first and then start the IPX.

No, NO. *NOVELL* IPX routers/servers don't change the Ethernet address
of any interface card (*).

We have several servers with two Ethernet cards. One card uses type
8137 protocoll and the other Novells ISO-like protocoll. Both are
connected to the *SAME* Ethernet segment, and if they used the same
Ethernet address it would mean disaster.

Looking with an Ethernet monitor you can see that at the link layer
each card uses its own address that it was born with. However, at the
network layer Novell IPX uses 32 bits of network id + 48 bits node id,
and the node id is the Ethernet address of the first (LAN A) card.

(*) The Cisco router, for some reason I don't understand, say they
    do change the adress of its interfaces when Novell IPX routing
    is turned on.
                                             
Jan Engvald, Lund University Computing Center
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