[Fwd:] Nvidia NICs with duplicate mac addresses

From: "Scott Berkman" <scott.berkman@reignmaker.net>
Date: Fri, 5 Sep 2008 10:53:28 -0400 (EDT)

This reminds me of a story I was told a while back that there was a batch
of 3com NIC's that all went out with the same MAC from the factory. I
never found out if that was a rumor/urban legend or the truth. Anyone
know firsthand or have an article about that?


From: Robert E. Seastrom [mailto:rs@seastrom.com]
Sent: Friday, September 05, 2008 10:33 AM
To: nanog@nanog.org
Subject: [Fwd:] Nvidia NICs with duplicate mac addresses

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...


Just when you thought this couldn't happen any more...

Copying from a different email list...

mac address 04:4b:80:80:80:03, was showing up in multiple places
across the network. I googled the mac address and discovered that
other people are having the same issue with this mac address. Below
are some links describing the problem:

I just wanted everyone to know about this problem in case you run
across similar slow "connectivity" issues. I believe the network card
is made by NVIDIA.

I can attest that it happened. We had several of them when I was at
LLNL back in the early '80s. It was amazingly hard to convince the 3Com
folks that the cards were not usable. (This is not the only case of
this, either, but was probably the biggest in terms of number of cards
as 3Com made a very large percentage of all cards in those days.

Back in 1999, I experienced an issue when we ghosted a number of Compaq
desktops and the Intel NICs all ended up with the same MAC address.
It turned out that the Intel NIC that was used in the later models was
different from the earlier models, so changing the driver resolved the

Eric Tow
York Telecom
E-mail: etow@yorktel.com
Phone: 732.413.6077