On 16June2014Monday, at 21:35, manning bill wrote:

thats always been true…. (that MACs are not universal and can be overwritten)

/bill PO Box 12317 Marina del Rey, CA 90295 310.322.8102

On 16June2014Monday, at 20:37, Jim Cheetham wrote:

...

I've just been writing some guidance for our internal network that will help people to use manually-allocated MAC addresses rather than hardware ones.

In order to indicate that these are Locally Administered MAC addresses properly, I need to set the "second-least-significant but of the most significant byte of the address", and to make them normal Unicast addresses the last bit should be a zero; therefore the last two bits will be "10" and unless my calculator has died converting things :-) in the standard hex representation the second character must be one of 2,6,A or E ...

So to double-check, I grabbed the current OUI list from IEEE http://standards.ieee.org/develop/regauth/oui/oui.txt and found 18 entries that match this pattern & therefore look like Local addresses.

$ egrep -i '^ +.[26AE]-' tmp/oui.txt 02-07-01 (hex) RACAL-DATACOM 02-1C-7C (hex) PERQ SYSTEMS CORPORATION 02-60-86 (hex) LOGIC REPLACEMENT TECH. LTD. 02-60-8C (hex) 3COM CORPORATION 02-70-01 (hex) RACAL-DATACOM 02-70-B0 (hex) M/A-COM INC. COMPANIES 02-70-B3 (hex) DATA RECALL LTD 02-9D-8E (hex) CARDIAC RECORDERS INC. 02-AA-3C (hex) OLIVETTI TELECOMM SPA (OLTECO) 02-BB-01 (hex) OCTOTHORPE CORP. 02-C0-8C (hex) 3COM CORPORATION 02-CF-1C (hex) COMMUNICATION MACHINERY CORP. 02-E6-D3 (hex) NIXDORF COMPUTER CORPORATION AA-00-00 (hex) DIGITAL EQUIPMENT CORPORATION AA-00-01 (hex) DIGITAL EQUIPMENT CORPORATION AA-00-02 (hex) DIGITAL EQUIPMENT CORPORATION AA-00-03 (hex) DIGITAL EQUIPMENT CORPORATION AA-00-04 (hex) DIGITAL EQUIPMENT CORPORATION

(I also found a single 'multicast' value in there, but it doesn't seem to be a problem :- $ egrep -i '^ +.[13579BDF]-' tmp/oui.txt 11-00-AA (hex) PRIVATE)

Some great old historical names on that list! Are these just relics of previous allocations, or are any of these in any meaningful way "live" in the real world?

-jim _______________________________________________ NZNOG mailing list NZNOG(a)list.waikato.ac.nz http://list.waikato.ac.nz/mailman/listinfo/nznog