Fresh install and the NICs are Broadcom b57 10/100/1000, I believe. ----- Reply message ----- From: "Randy McAnally" <rsm@fast-serv.com> Date: Sun, Jan 2, 2011 8:53 am Subject: The tale of a single MAC To: "Graham Wooden" <graham@g-rock.net>, <nanog@nanog.org> ---------- Original Message ----------- From: Graham Wooden <graham@g-rock.net>

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.

Fresh OS install from scratch or did you load an image from an existing server? What make/model of on-board NICs? -- Randy M.