[Fwd:] Nvidia NICs with duplicate mac addresses

Robert E. Seastrom rs at seastrom.com
Fri Sep 5 12:19:44 CDT 2008

"David W. Hankins" <David_Hankins at isc.org> writes:

> On Fri, Sep 05, 2008 at 10:32:46AM -0400, Robert E. Seastrom wrote:
>> Forwarded to NANOG in the interests of wider awareness...  having been
>> there and torn out my already scarce hair, duplicate MAC addresses can
>> really mess up your day...
> Out of curiosity, does this happen often enough we might want to
> consider an automated means to negotiate out of the problem state
> (e.g. detect collisions and negotiate MAC address by DHCP)?
> It would take years to deploy but might save thousands of hairs.

The same DHCP server (ip helper-address blah) serves my office, my
home, and the colo.  Can you give me an idea of a good heuristic for
telling the difference between moving my laptop around and finding MAC
address collisions?  Or are you suggesting that you hand out a MAC
address along with an IP address when the client DHCPs and the client
then changes it?


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