Subject: Re: Changing the physical address of an interface
To: Eric Varsanyi <ewv@boom.bsdi.com>
From: Matt Thomas <matt@lkg.dec.com>
List: tech-net
Date: 07/05/1996 15:27:54
> We are considering doing exactly this in a future release, although
> probably just the simple SIOCSIFADDR (is there really a need for
> multiple mac addresses? how would ethersubr decide which one to
> use when sending -- protocol?).

The problem of switching hardware adddresses means that the hardware
driver needs to be much more careful in cleaning up transmits since
if you lose (by reseting or whatever) the ARP message telling everyone
of your new address, you lose IP connectivity real fast.

In the DECnet case, a simple addition ether_output or fddi_output would
take care of it.  Note that for FDDI, you can really never disable the
original hardware address (the MLA).  Since that's the case, make life
easier and just leave all the protocols except the ones that needs the
new address unaware of the change.  And then, if you are doing to do that
for FDDI and since some Ethernet devices can support multiple addresses,
why support them too?

-- 
Matt Thomas               Internet:   matt@3am-software.com
3am Software Foundry      WWW URL:    http://www.3am-software.com/bio/matt.html
Westford, MA              Disclaimer: I disavow all knowledge of this message