Re: what about 48 bits?

[John Peach <john-nanog () johnpeach com>]

On Sun, 04 Apr 2010 14:48:38 -0700
Jim Burwell <jimb () jsbc cc> wrote:

> On 4/4/2010 08:46, Jonathan Lassoff wrote:
> > Excerpts from John Peach's message of Sun Apr 04 08:17:28 -0700 2010:
> >   
> > > On Sun, 4 Apr 2010 11:10:56 -0400
> > > David Andersen <dga () cs cmu edu> wrote:
> > >
> > >     
> > > > There are some classical cases of assigning the same MAC address to every machine in a batch, resetting the 
> > > > counter used to number them, etc.;  unless shown otherwise, these are likely to be errors, not accidental 
> > > > collisions.
> > > >
> > > >   -Dave
> > > >
> > > > On Apr 4, 2010, at 10:57 AM, jim deleskie wrote:
> > > >
> > > >       
> > > > > I've seen duplicate addresses in the wild in the past, I assume there
> > > > > is some amount of reuse, even though they are suppose to be unique.
> > > > >
> > > > > -jim
> > > > >
> > > > > On Sun, Apr 4, 2010 at 11:53 AM, A.B. Jr. <skandor () gmail com> wrote:
> > > > >         
> > > > > > Hi,
> > > > > >
> > > > > > Lots of traffic recently about 64 bits being too short or too long.
> > > > > >
> > > > > > What about mac addresses? Aren't they close to exhaustion? Should be. Or it
> > > > > > is assumed that mac addresses are being widely reused throughout the world?
> > > > > > All those low cost switches and wifi adapters DO use unique mac addresses?
> > > > > >
> > > > > >           
> > > Sun, for one, used to assign the same MAC address to every NIC in the
> > > same box.
> > >     
> > I could see how that *could* work as long as each interface connected to
> > a different LAN.
> >   
> That was a logic Sun used.  Every NIC would be connected to a different
> subnet, so duplicate MACs shouldn't be a problem.  For the most part
> this worked, but some situations required a unique MAC per NIC, and Sun
> had a bit you could flip to turn this on.  I believe it was an OpenBoot
> prom variable called "local-mac-address?" which you'd set to true if you
> wanted it to use each NICs MAC instead of the "system MAC".

You can set the MAC address to whatever you want in Solaris, using
ifconfig and local-mac-address was (is) the PROM variable.


-- 
John