nanog mailing list archives
Re: what about 48 bits?
From: "Kevin Oberman" <oberman () es net>
Date: Sun, 04 Apr 2010 22:26:52 -0700
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
Current thread:
- Re: Hubs on a NIC (was:Re: what about 48 bits?), (continued)
- Re: Hubs on a NIC (was:Re: what about 48 bits?) Joe Greco (Apr 07)
- Re: Hubs on a NIC (was:Re: what about 48 bits?) Steven Bellovin (Apr 07)
- Re: Hubs on a NIC (was:Re: what about 48 bits?) Joe Greco (Apr 08)
- Re: Hubs on a NIC (was:Re: what about 48 bits?) Roland Perry (Apr 08)
- Re: what about 48 bits? Michael Thomas (Apr 07)
- Re: what about 48 bits? Michael Thomas (Apr 07)
- Re: what about 48 bits? Roland Perry (Apr 08)
- Re: what about 48 bits? A.B. Jr. (Apr 04)
- Re: what about 48 bits? Scott Howard (Apr 04)
- Re: what about 48 bits? Larry Sheldon (Apr 04)
- Re: what about 48 bits? Kevin Oberman (Apr 04)
- Re: what about 48 bits? Valdis . Kletnieks (Apr 05)
- Re: what about 48 bits? Patrick W. Gilmore (Apr 05)
- Re: what about 48 bits? Valdis . Kletnieks (Apr 05)
- Re: what about 48 bits? joel jaeggli (Apr 05)
- Re: what about 48 bits? Jon Lewis (Apr 06)
- Re: what about 48 bits? Mark Smith (Apr 04)