Chapter 1 2: Layer 4 - The Transport Layer Media:

12.1.1 | Layer 4 - Transport Layer Transport Layer Analogies
12.1.2. | Transport Layer Overview
12.1.3. | TCP and IP
12.2.1 | Protocol Graph: TCP/IP TCP Segment Format
12.2.2 | Protocol Graph: TCP/IP UDP Segment Format
12.3.1 | Port Numbers Reserved TCP Port Numbers Reserved UDP Port Numbers FTP Port Numbers
12.3.2 | TCP Three-Way Handshake/Open Connection TCP Three-Way Handshake/Open Connection TCP Three-Way Handshake/Open Connection TCP Sequence and Acknowledgement Numbers