Re: what about 48 bits?

[Jonathan Lassoff <jof () thejof com>]

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.

Maybe the NICs shared a single MII/MAC sublayer somehow? I've never
borne witness to this though.


Re: MAC address exhaustion, if the the second-to-least significant bit
in the first byte is 0 (Globally Unique / Individually Assigned bit),
then the first three bytes of the MAC should correspond to the
manufacturer's "Organizationally Unique Identifier". These are
maintained by the IEEE, and they have a list of who's who here:
http://standards.ieee.org/regauth/oui/index.shtml


I haven't ever programmatically gone through the list, but it looks like
a lot of the space is assigned.

Cheers,
jof