Mac address changes upon reboot on PE2950

Robert von Bismarck robert.vonbismarck at
Tue Feb 1 10:41:32 CST 2011


We had an issue this morning, where one of our servers (PowerEdge 2950
GenII) changed the mac address of it's on-board NICs to something
different during or after a reboot.
The server was updated using 'yum update' from CentOS 5.3 to CentOS 5.5
(x86_64) and was then rebooted. After that the mac addresses were
changed. The funny thing is that a second identical server did not
exhibit this behavior and rebooted cleanly. 
Nothing was changed in the configuration preceding the upgrade+reboot.
Of course the victim of this unwanted change did not reboot cleanly and
was unreachable on the network until someone went to the console and
checked what was wrong.

Here's the different mac addresses :

Old eth0: HWADDR=00:1A:A0:38:EC:XX
New eth0: HWADDR=00:1A:A0:11:8B:YY
Old eth1: HWADDR=00:1A:A0:38:EC:XX+2
New eth1: HWADDR=00:1A:A0:11:8B:YY+2

We have then rebooted the server a couple more times, and nothing went

So I'm asking if anyone has seen this behavior before, as I can't point
out if this is a Dell issue, a Linux issue, a CentOS issue, or just
plain old magic ?

Thanks for any help,

Robert von Bismarck
Senior Systems Engineer





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