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 <d...@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. <skan...@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