[rchiang]

I'd make the argument that TCP/IP Illustrated Volume 1 covers the details of TCP/IP in a very "packet and fields" oriented way. Volume 2 goes into a lot of the "data structures and implementation" way. That makes for a very good supplemental reference, but makes for a less than ideal introductory textbook on the subject of computer networking.

Kurose's book really does take the top-down approach from high level networking concepts through the application layer to the transport layer and downward. It provides just enough of the necessary details (here's a datagram with fields A and B) over a comprehensive list of all the details (here's every field, every field size, and a list of every field option).