In addition to the Stevens books already mentioned, there's also volume 2 of Comer's Xinu OS book: Operating System Design, Vol. 2: Internetworking with Xinu,

In addition to the Stevens books already mentioned, there's also volume 2 of Comer's Xinu OS book: Operating System Design, Vol. 2: Internetworking with Xinu, ISBN-13: 978-0136374145 (https://www.amazon.com/Operating-System-Design-Vol-Internetworking/dp/013637414X https://www.amazon.com/Operating-System-Design-Vol-Internetw...). Unfortunately, this book was written in 1987, so it's a bit dated (e.g. no IPv6). I think it's still useful to learn the basics of a TCP/IP implementation.