This article describes the addressing scheme of Ethernet controllers on Macintosh computers.

Ethernet Controllers Addressing Scheme

Beginning with the Macintosh Quadra computers, when Apple started including Ethernet on the main logic board, all Ethernet controllers were capable of 32 bit addressing. This included the Comm Slot and Comm Slot II Ethernet cards, as well as the "short" Ethernet NB card.

If you are concerned about the capabilities of other Ethernet network devices, you should check with the manufacturer of the Ethernet controller chip being used.