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Date:      Thu, 20 Apr 2000 16:11:48 -0700 (MST)
From:      "Chad R. Larson" <chad@DCFinc.com>
To:        Ronald.vanderPol@surfnet.nl (Ronald van der Pol)
Cc:        freebsd-stable@FreeBSD.ORG
Subject:   Re: setting Ethernet address on Ethernet card?
Message-ID:  <200004202311.QAA08703@freeway.dcfinc.com>
In-Reply-To: <Pine.BSF.4.21.0004202355040.25898-100000@sure.surfnet.nl> from Ronald van der Pol at "Apr 21, 0 00:01:23 am"

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As I recall, Ronald van der Pol wrote:
> Is it possible to change the Ethernet address on an Ethernet card?

It depends on the card.  Some can (usually more expensive, high end),
some can't (clones and cheapies).  Those that can are usually so as
to be able to support Ethernet multicasting, or High Availablity
failovers and the like.

A major issue is that the Ethernet address (the MAC, in IEEE 802.3
parlance) is supposed to be unique.  It =has= to be unique within
any collision domain.  The manufacturers work that out by allowing
the IEEE to assign the first 24 bits of the address to each
manufacturer, and then the manufacturer picks the lower 24 bits
(like a serial number).  Clever line monitors can tell you the
manufacturer of the card that sent an Ethernet packet.

If you multicast, the spec says you've taken upon yourself the
responsibility for a unique MAC address.

> If yes, how can I do this? 

Again, depends on the card.  If it can, the place where FreeBSD
should do it is in the device driver, controlled by an option to
ifconfig.

I don't know of any support for that.

There might be an MS-DOS utility available from the manufacturer, if
the card hardware supports it.

	-crl
--
Chad R. Larson (CRL15)   602-953-1392   Brother, can you paradigm?
chad@dcfinc.com         chad@larsons.org          larson1@home.net   
DCF, Inc. - 14623 North 49th Place, Scottsdale, Arizona 85254-2207


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