Video presentation: Network Layer: Middleboxes, Internet architecture, data-plane wrap-up
Computer networks class.

Jim Kurose
Textbook reading: Section 4.5 and 4.6, Computer Networking: a Top-Down Approach (8th edition), J.F. Kurose, K.W. Ross, Pearson, 2020.
See http://gaia.cs.umass.edu/kurose_ross for more open student resources.