Subject: Re: MAC addresses
To: None <>
From: Justin C. Walker <>
List: tech-net
Date: 07/23/1998 10:48:01
 * > Note that there are 2 things here: the hard ethernet address, and the
 * > station address. The station address is the one that is used when
 * > matching eligible packets, the other one is always used for outgoing
 * > packets.
 * > 
	I don't think this is accurate.  At least in most adapters I'm
familiar with, the "hard" address, the one programmed into the ROM, is
not directly connected to the adapter itself.  The driver must read
that address from the ROM and write it into the adapter.  The address
recognition is based on what's dynamically written into the adapter,
not what's burned into the ROM.  AFAIK, most adapters assume the
driver is going to put the source address into the packet before
transmitting.  The only thing the adapter adds on output is the FCS.

 * Argh. So this will not work. We really need to change the prom :(
	As others have indicated in this thread, you should be able to
change the address under program control.  You'll probably have to
think through a few issues like ARP if you do this after the system
has transmitted packets, though.



Justin C. Walker, Curmudgeon-At-Large   *
Institute for General Semantics         | They sentenced me to 20 years
Apple CoreOS Networking                 |       of boredom
Apple Computer, Inc.                    | For trying to change the system
2 Infinite Loop                         |       from within
Cupertino, CA 95014                     |               LC