CCNP Routing and Switching ROUTE 300-101 Official Cert Guide

The Basics of Internet Routing and Addressing

The original design for the Internet called for the assignment of globally unique IPv4 addresses for all hosts connected to the Internet. The idea is much like the global telephone network, with a unique phone number, worldwide, for all phone lines, cell phones, and so on.

To achieve this goal, the design called for all organizations to register and be assigned one or more public IP networks (Class A, B, or C). Then, inside that organization, each address would be assigned to a single host. By using only the addresses in their assigned network number, each company’s IP addresses would not overlap with other companies. As a result, all hosts in the world would have globally unique IP addresses.