nanog mailing list archives

Re: The tale of a single MAC


From: Brielle Bruns <bruns () 2mbit com>
Date: Sat, 01 Jan 2011 20:59:16 -0700

On 1/1/11 8:33 PM, Graham Wooden wrote:
So ­ here is the interesting part... Both servers are HP Proliant DL380 G4s,
and both of their NIC1 and NIC2 MACs addresses are exactly the same.  Not
spoofd and the OS drivers are not mucking with them ... They¹re burned-in ­
I triple checked them in their respective BIOS screen.  I acquired these two
machines at different times and both were from the grey market.  The ³What
the ...² is sitting fresh in my mind ...  How can this be?


From the same grey market supplier?

I know HP has a disc they put out which updates all the firmware/bios in a specific server model, its not too far fetched that a vendor might have a modified version that also either purposely or accidentally changes the MAC address. Off the top of my head, I'm not sure where the MAC is stored - maybe an eeprom or a portion of the bios flash. Or, it could be botched flashing that blew away the portion of memory where that was stored and the system defaulted to a built in value.

Excellent example is, IIRC, the older sparc stuff, where the ethernet cards didn't have MAC addresses as part of the card, but were stored in non-volatile or battery backed memory. Memory goes poof, and you'll have problems. Some WRT54G/WAP54Gs suffer from the same problem when throwing third party firmware on there.

--
Brielle Bruns
The Summit Open Source Development Group
http://www.sosdg.org    /     http://www.ahbl.org


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