The world in which IPv6 was a good design (2017)

To save on electronics, people wanted to have a “bus” network (also known as a “broadcast domain,” a name that will be important later) where multiple stations could just be plugged into a single wire, and talk to any other station plugged into the same wire. Various LAN technologies came and went, including one of my favourites, IPX (Internetwork Packet Exchange, though it had nothing to do with the “real” Internet) and Netware, which worked great as long as all the clients and servers were on a single bus network. Devices on ethernet already had addresses, MAC addresses, which were about the only thing the various LAN protocol people could agree on, so they decided to use ethernet addresses as the keys for their routing mechanisms.

Source: apenwarr.ca