CISCO IOS in a Nutshell

Chapter 1. Getting Started

Introduction

The modern world is networked in a way that could barely be imagined a few decades ago. Today, the Internet reaches into virtually every business and almost every home. Our children and even our grandparents speak of dot-coms, email, and web sites. The Internet is now part of our culture.

Routers are the glue that holds the Internet together. And Cisco is the most prominent router manufacturer, holding the largest share of the market. Their routers come in all sizes, from inexpensive units for homes and small offices to equipment costing well over $100,000 and capable of routing at gigabit speeds. One of the most impressive facts about their product line is its unified operating system. Almost all of their routers, as well as half of their switches—from the smallest to the largest—run the Internetwork Operating System (IOS). Therefore, they share the same command set, the same user interface, and the same configuration techniques. While an 800-series home router doesn’t have the features or the capacity of a 7500-series router that might be used to connect an ISP to an Internet backbone, you configure them the same way. Both routers use access lists, have similar security mechanisms, support the same set of protocols in the same way, and so on. A home router probably wouldn’t have a Frame Relay interface, but if it did, it would be configured just like a Frame Relay interface on a mid-sized corporate router.

IOS is an extremely powerful and ...