OP here. I think the best would be to do the labs in posted link, after watching the great video lectures (which have quizzes but are lacking labs) in the free online Stanford course: https://lagunita.stanford.edu/courses/Engineering/Networking...

AFAIK this combination would be the best free computer networking course out there, specially if combined with the MIT 6.033 systems engineering videos, to understand complex systems design concepts in a wider context, and how they were applied, in particular, to the internet and the ethernet.

Also, regarding ethernet, there is a realy good old presentation by Metcalfe in youtube: https://youtu.be/Fj7r3vYAjGY