IP Routing Primer

Introduction to Terminology

Before proceeding any further in this chapter, it is important to lay the groundwork for the discussion by defining some terms, as follows:

• A major net(work) refers to the network-only portion of an Internet address. In Figure 3-1, the major net of subnet 168.71.5.0 is 168.71.0.0 because Class B addresses use only the first two of the four bytes in an IP address to determine the network address space. The other two bytes can be used for host addresses or a combination of subnets and host addresses. In other words, the term major net is used for the bytes of an address that are reserved for the network portion, based on the class of address in use. The major net for address 10.9.0.0 is 10.0.0.0. The major net for ...