Date: Sun, 04 Apr 2010 23:30:42 -0500 From: Larry Sheldon <LarrySheldon@cox.net>
I keep seeing mention here of the "permanent" MAC address.
Really? Permanent?
Been a long time, but it seems like one of the fun things about having DECNet-phase IV on the network was its propensity for changing the MAC address to be the DECNet address.
And it seems like the HP-UX machines (among others) could write what every they wanted to as addresses.
Almost every system can re-write the MAC address. It's in the original 802.3 and DIX (Blue Book) Ethernet standards. I have not run into a system in some time that lacked this capability. Works on Windows, MacOS, Linux, and BSD. That said, all 802.3 devices are expected to have a permanent MAC address in ROM. At initialization time, that address is always used until software can program in the new address. Made MOP-DL booting (DECnet equivalent of bootp) interesting. -- R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: oberman@es.net Phone: +1 510 486-8634 Key fingerprint:059B 2DDF 031C 9BA3 14A4 EADA 927D EBB3 987B 3751