An excellent podcast on internet security, Security Now by Steve Gibson and Leo Laporte has done several episodes on how the internet works, and how ethernet works. Shows 25 and 26, are how the internet works, and shows 27 and 29 are about local area networks. I’m not particularly interested or worried about security, and these shows are security minded, but they do an excellent job of explaining everything. They really make sure that anybody could understand it, and it gives you a real appreciation for the people who came up with the amazing technology that makes the internet possible. Go check ‘em out