Ciaran McCreesh wrote:
> On Wed, 13 Oct 2004 11:37:50 +0200 Bart Braem <bart.braem@gmail.com>
> wrote:
> | > Naming by MAC only works if you're on a broken box which violates
> | > the Ethernet spec. MACs are per-machine, not per-NIC. If you're
> | > after persistent names, there's some clever way to do it using udev
> | > -- best to check the docs rather than me trying to remember it
> | > though :)
> | >
> | MAC are per NIC settings, per machine would be problematic if you'd
> | connect with 2 NICs on the same network. It will be rather interesting
> | to see what ARP would do and which networknode would crash first!
>
> Bzzzzt, ping, you lose! The Ethernet spec puts MAC addresses on a
> per-machine basis, and does not consider having multiple NICs on the
> same subnet. The only reason your NICs have their own MAC addresses is
> because the PC BIOS didn't include its own MAC (unlike anything OFW or
> OBP based).
>
Not true. From the IEEE 802-2001 spec (section 9.2.3):
"The recommended approach is for each device associated with a distinct
point of attachment to a LAN to have its own unique MAC address.
Typically, therefore, a LAN adapter card (or, e.g., an equivalent chip
or set of chips on a motherboard) should have one unique MAC address for
each LAN attachment that it can support at a given time.
NOTE—It is recognized that an alternative approach has gained currency
in some LAN implementations, in which the device is interpreted as a
complete computer system, which can have multiple attachments to
different LANs. Under this interpretation, a single LAN MAC address is
used to identify all of the system’s points of attachment to the LANs in
question. This approach, unlike the recommended one, does not
automatically meet the requirements of IEEE Std 802.1D-1998 MAC bridging."
You can get the whole spec at
http://standards.ieee.org/getieee802/802.html --
Manuel A. McLure KE6TAW <manuel@mclure.org> <
http://www.mclure.org>
...for in Ulthar, according to an ancient and significant law,
no man may kill a cat. -- H.P. Lovecraft
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