what about 48 bits?

joel jaeggli joelja at bogus.com
Mon Apr 5 23:56:55 CDT 2010

On 4/5/2010 5:26 PM, Patrick W. Gilmore wrote:
> On Apr 5, 2010, at 5:08 PM, Valdis.Kletnieks at vt.edu wrote:
>> On Mon, 05 Apr 2010 16:36:26 EDT, Jon Lewis said:
>>> Since they only really need to be unique per broadcast domain, it
>>> doesn't really matter.  You can I could use the same MAC
>>> addresses on all our home gear, and never know it.  For
>>> manufacturers, it's probably reasonably safe to reuse MAC
>>> addresses they put on 10mbit ISA ethernet cards...if they were a
>>> manufacturer back then.
>> Until you buy 25 cards with the same MAC address and deploy them
>> all across your enterprise
> I don't think that's possible given that Jon was suggesting.
> I'm 3COM, I made ISA 10Base2 / 10Base5 cards in the 90s.  I run out
> of MAC addresses.  Instead of going to get more - if I even can! - I
> recycle those MAC addresses, figuring the 10GE PCI-X cards I'm making
> now have 0.000% chance of being on the same b-cast domain as one of
> those old ISA cards.
> Even if I am wrong, the max collision possibility is 2, not 25.
> Seems reasonable.  If I am wrong, I'll apologize profusely, refund
> the price of the 10G card I gave the customer, ship him a new one
> free, so he gets two he can use (assuming he has more than one b-cast
> domain), which would probably make the customer happy.  Wanna bet how
> many times 3COM would have to ship free 10GE cards?

3com is now HP and i doubt very much that either company would bother 
with that approach...

That said, the volume production run for a circa 1992 isa bus ethernet 
nic (or the enitre sun microsystems product line for that matter) is 
propably two orders of magnitude lower than say the minimum volume 
production of mini-pci-express wireless card that goes into a laptop, 
and laptops might have two or three mac addresses.

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