The tale of a single MAC

Mon Jan 3 09:40:02 UTC 2011

On Mon, jan 03, 2011 at 07:05:24, Mikael Abrahamsson wrote:
> Subject: Re: The tale of a single MAC
> 
> On Mon, 3 Jan 2011, Dobbins, Roland wrote:
> 
> > I remember that there were several high-profile instances of
> duplicate
> > MAC addresses being burnt into NICs during the 1990s - once every 
> > 2-3 years, IIRC.  And those were just the ones that were discussed
> publicly.
> 
> D-Link shipped NAT-boxes around 2003-2004 or so with identical MAC 
> addresses (and a "clone your PC mac address to the WAN interface"- 
> functionality). I checked my then employer ADSL network and 5% of the 
> customer ports had the same MAC address, D-Link support alledgedly 
> said something about the MAC address not being "unique enough" and 
> directed their customers to the cloning functionality to "solve" the
problem.
> 
> --
> Mikael Abrahamsson    email: swmike at swm.pp.se

Years ago D-link and Linksys and maybe other vendors used the source MAC of
00:00:00:00:00:00 which isn't very nice and could cause interesting issues.
At my current job we used to have a routine to find these MACs and tell the
users to change to a valid address.