The TCP/IP Guide  9  TCP/IP Lower-Layer (Interface, Internet and Transport) Protocols (OSI Layers 2, 3 and 4)       9  TCP/IP Transport Layer Protocols            9  Transmission Control Protocol (TCP) and User Datagram Protocol (UDP)                 9  TCP/IP Transmission Control Protocol (TCP)

TCP Characteristics: How TCP Does What It Does 1 TCP Data Handling and Processing: Streams, Segments and Sequence Numbers

Many people have a difficult time really understanding how the Transmission Control Protocol works. (After spending dozens of hours writing almost 100 pages on the protocol, I am quite sympathetic.) I think a main reason for the difficulty in absorbing TCP is that too many descriptions of the protocol quickly jump from a brief introduction straight into the mind-boggling details of TCP's operation. The problem is that TCP has a very particular way of doing certain things. Its operation is built around a few very important fundamentals that it is essential to understand before the details of TCP operation will make much sense.

In this section I describe some of the key operating fundamentals of TCP. I begin with a discussion of how TCP handles data, and introduce the concepts of streams, segments and sequences. I then describe the very important TCP sliding window system, used for acknowledgment, reliability and data flow control. I discuss how TCP uses ports, and how connections are identified. I also describe the most important applications that use TCP and what ports they use for server applications.

TCP Characteristics: How TCP Does What It Does 1 TCP Data Handling and Processing: Streams, Segments and Sequence Numbers