Hi
Download the open source version of the uTasker project from GITHUB and follow this tutorial:
https://www.utasker.com/docs/KINETIS/uTaskerV1.4_Kinetis.pdf
It runs a simulated Kinetis part with its Ethernet module so you can do both practical tests and step through the code to see how the Ethernet module operates (how it is configured, controlled and how it works internally - address filltering, interrupt generation, buffer copying and so on).
Regards
Mark
[uTasker project developer for Kinetis and i.MX RT]