It ran on top of several things. I remember the company I worked for (Alfa Systems) uploading IPX drivers to Novell for testing over a modem using IPX as a protocol.

Alfa designed Sage Mainlan originally a z8530 + RS485(?) PC card followed by a 10Mbps Ethernet with our own chip design (Enzo) fabbed as an ASIC by Toshiba. We wrote IPX drivers for both versions.

Interestingly we could hang systems with the 3COM cards in our test systems if we ran at full speed and at somepoint we had the full 500 metres of thick ethernet in the office.

The IPX version that came with Netware 3 was rather nice, I seem to recall it had a buffer of segments and these got filled by the different layers of the network stack as needed along with some fancy protocol filtering so your code only saw just the data packets it was interested in.

Did IPX run on ARCnet? I remember ARCnet being popular in the DOS world.

It could, but not the further step of running on top of TCP/IP, which is why software like Kali [0] was needed if you wanted to play over the internet.

[0] https://en.wikipedia.org/wiki/Kali_(software)