If you want to get a good basic understanding of how basic networking works, you could do worse than to take the ProCurve Networking Primer. It offers the fundamentals in an easy to understand self-paced course. It doesn't have a lot of vendor bias in it.
HP offers a great deal of training in fundamentals for free. Some of it is specific to their products and some of it is not. On the ProCurve Training page you will find some materials to study if you are interested in these things. It's accessible to the public.
A lot of the HP training is available free to the public but it's hidden behind a membership page so people can't find it easily. This is silly because the training itself is hosted on a public FTP server. For example the exam preparation guides are in the epgs directory. There's quite a lot of interesting stuff on ftp.hp.com and it's wide open for browsing.
IBM also has a good deal of online training available here.
Naturally MIT's Open CourseWare covers networking as well