CHAPTER 8

Classless IP Addressing

Chapter 7, “Classful IP Addressing,” introduced IP addressing. One important aspect of IP addressing is that for two devices to communicate with one another, the devices must be in the same network. There are two parts of an IP address: the network part and the host part. The network portion of the IP address must match on the two devices for communication to be possible, even if they reside on the same physical segment.

Much of what was discussed in Chapter 7 is characteristic of classful networking. This was the original design of IPv4 networking. In classful networking, there are three classes of IP addresses that may be assigned to individual devices. The size of the network in which a computer resides is a function of the address class used for the network. Computers determine the network class from a second configuration value called the subnet mask.

In this chapter, you'll review the limitations of the classful networking design and discuss the benefits of departing from the restrictions of using the three default classes. Specifically, this chapter covers the following topics:

• Understanding the limitations of classful networking
• Understanding the benefits of subnetting
• Describing the components of CIDR