Introduction

This chapter will discuss the purpose of routing and the many issues that arise from routing in various network environments, from smaller networks to very large, complicated, dynamic networks such as the Internet. We will introduce the many routing protocols, such as the Routing Information Protocol (RIP), Open Shortest Path First (OSPF), and Border Gateway Protocol (BGP), and discuss the characteristics and issues involved with each. Each routing protocol has its own set of strengths and weaknesses that you will need to assess in order to understand how to implement this protocol. You will also see how these routing protocols are addressing the issue of the exhaustion of available IP addresses, the introduction of the IPv6 protocol, and the concern for growing routing tables on major routers on the Internet.

As most people know, the rate of growth on the Internet is phenomenal, and usage has increased nearly exponentially. Networks and hosts are being added to the Internet, which threatens to eat up every available IP address unless something is done. Not only is the exhaustion of available IP addresses an important issue, we also have to deal with the tremendous amount of routing that takes place on the Internet. Routers are network devices used to route packets to different networks on the Internet. The Internet is composed of hundreds of thousands of different networks. Routers use a routing table, which is an internal table that contains routes to networks and other routers. In most routers found on...