That makes the resources that aren't proprietary extremely detailed and muddy, to cover things the proprietary tech shines up at a high level.
Therefore, my suggestion for 'learning networking' is to just do it. Set up a LAN at home. Solve the problems as you come across them.
Someone at my place of work took this approach, and I thought it made me smile when he said he had this great idea about how he could automatically distribute IP addresses to terminals instead of manually setting them up. I told him about DHCP! Learning by going through the motions.
Incidentally, I picked up a copy of a CCNA study guide and the concept of DHCP wasn't covered until 1/3 through the book, after OSI was covered and other low-level topics.