On Sun, 2 Jan 2011, Steven Bellovin wrote: > > This was actually the intended way to use "MAC" addresses, to used as > > host addresses rather than as individual interface addresses, according > > to the following paper - > > > > "48-bit Absolute Internet and Ethernet Host Numbers" > > Yogan K. Dalal and Robert S. Printis, July 1981 > > http://ethernethistory.typepad.com/papers/HostNumbers.pdf > > Yup. > > > > That paper also discusses why 48 bits were chosen as the size, despite > > "Ethernet systems" being limited to 1024 hosts. > > > > I think things evolved into MAC per NIC because when add-in NICs > > were invented there wasn't any appropriate non-volatile storage on the > > host to store the address. > > > On really old Sun gear, the MAC address was stored on a separate ROM > chip; if the motherboard was replaced, you'd just move the ROM chip to > the new board.
And I'm sure many will remember that Suns of a certain vintage with multiple ethernet interfaces would use that same "host" MAC address on all those interfaces, unless you weaved some magic in the eeprom to use the (presumably) burned-in MAC address of the interface itself. I have long forgotten precisely what the incantation was now ... Jethro. . . . . . . . . . . . . . . . . . . . . . . . . . Jethro R Binks, Network Manager, Information Services Directorate, University Of Strathclyde, Glasgow, UK The University of Strathclyde is a charitable body, registered in Scotland, number SC015263.
