Chapter 1. TCPIP Review

Chapter 1. TCP/IP Review

This chapter covers the following subjects:

• TCP/IP Protocol Layers

• IP Packet Header

• IPv4 Addresses

• Address Resolution Protocol (ARP)

• Internet Control Message Protocol (ICMP)

• Host-to-Host Layer

Given that the title of this book is Routing TCP/IP, it is fitting to begin with a review of TCP/IP before getting into how to route it. Presumably, if you are preparing for a Cisco Certified Internetwork Expert (CCIE) examination, or have just bought this book as a routing reference, you already know most or all of the information in this chapter. But reviews never hurt and sometimes help, so here you have it.

The purpose of this chapter is to review the protocols that enable, control, or contribute to the routing of TCP/IP, not to do an in-depth study of the TCP/IP protocol suite. Several books on the recommended reading list at the end of the chapter cover the subject in depth. Read at least one.

Conceived in the early 1970s by Vint Cerf and Bob Kahn, TCP/IP and its layered protocol architecture predates the ISO's Open System Interconnection (OSI) reference model. A brief review of TCP/IP's layers will be useful in understanding how the various functions and services examined in this chapter interrelate.