Computer Networking: Internet Protocols in Action

Chapter 4.1. Joining the Internet: Introduction to IP and DHCP

INTRODUCTION

The Internet Protocol (IP) is the backbone of the Internet. It defines the way in which a collection of independent networks can work together to form a global network of networks. Each host in the Internet is given an IP address. Data is sent from host to host in packets called datagrams. Each datagram is labeled with both source and destination IP addresses and sent out into the network. If source and destination machines are not on the same local network, then intermediate machines called routers receive the transmitted datagram and send it one step closer to its destination. This process is called packet switching.

For early Internet researchers, packet switching was an important new idea. Other global communication networks like the telephone network did not use packet switching. Instead, these networks established a fixed circuit between source and destination and sent all traffic over this connection. In packet switched networks, packets do not travel along established circuits; instead they are individually addressed and routed through the network.

The Internet Protocol allows datagrams to travel from source to destination over many different networks. Each network may have its own rules and conventions; IP allows datagrams to adapt to each network it traverses. For example, the maximum amount of data that can be sent as a unit varies from network to network. IP allows datagrams to be broken into smaller ...