The tale of a single MAC

Franck Martin franck at
Sun Jan 2 15:24:03 CST 2011

In the early 90's a friend of mine got a box of 10 HP cards with all the same MAC address.

----- Original Message -----
From: "Graham Wooden" <graham at>
To: nanog at
Sent: Sunday, 2 January, 2011 4:33:46 PM
Subject: The tale of a single MAC

Hi there,

I encountered an interesting issue today and I found it so bizarre ­ so I
thought I would share it.

I brought online a spare server to help offload some of the recent VMs that
I have been deploying.  Around the same time this new machine (we¹ll call it
Server-B) came online, another machine which has been online for about a
year now stopped responding to our monitoring (and we¹ll name this
Server-A). I logged into the switch and saw that the machine that stopped
responding was in the same VLAN as this newly deployed, and then quickly
noticed that Server-A¹s MAC address was now on Server-B¹s switch port.
³What the ...² was my initial response.

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