Chapter 5. TCPIP

Chapter 5. TCP/IP

Terms you'll need to understand:

• TCP

• IP

• FTP

• UDP

• ARP

• RARP

• DNS

• Application layer

• Transport layer

• Internet layer

• Network Access layer

• Subnetting

• Dotted decimal notation

• Well-known port numbers

Techniques you'll need to master:

• Subnetting

• Identifying the various layers of the TCP/IP model

• Identifying the different classes of IPs

• Performing a conversion from binary to dotted decimal notation

The Transmission Control Protocol/Internet Protocol ( TCP / IP ) is the foundation of the Internet and the single most widely used protocol suite in the world today. A detailed working knowledge of TCP/IP is required for the CCNA exam, so it is very important you feel comfortable with everything presented in this chapter.

TCP/IP is not just a protocol, it is an entire suite of protocols which, together, provide comprehensive rules and standards for communications (interdependent protocols are called a protocol suite or protocol stack ). Most presentations of TCP/IP begin by showing how these protocols fit into the OSI model. The only problem with this approach is that TCP/IP does not fit into the OSI model (and you thought we were kidding in Chapter 3, "Hardware and OSI Model," when we said the OSI model is good, it just does not describe how anything really works).

TCP/IP was developed under a four-layer model called the Department of Defense model or DoD model . We will show you how these two models map to each other as well as how the protocol suite fits into either model, because you will need to know this for the test. However, if integrating TCP/IP into the OSI model seems a bit awkward to you, it is only because it is.