> MAC address can be assigned in arbitrarily small blocks Not really. Of the 48b available, the first 24 are assigned to an organization: * https://en.wikiped

> MAC address can be assigned in arbitrarily small blocks Not really. Of the 48b available, the first 24 are assigned to an organization: * https://en.wikipedia.org/wiki/Organizationally_unique_identifier https://en.wikipedia.org/wiki/Organizationally_unique_identi... * http://standards-oui.ieee.org/oui/oui.txt http://standards-oui.ieee.org/oui/oui.txt then they can assigned the other 24b as they wish. This is in some way similar to an IP prefix being assigned, which can then be used however the assignee wishes. 48b would have lasted longer than 32, perhaps delaying the need for NAT (RFC 1631 from 1994), but certainly at some point an address extension would have been needed. Of course in the 1970s it would have been hard/impossible to predict needing more than four billion addresses for a research/academic network.