Chapter 1. Fundamental IOS Software Architecture

This chapter covers the following key topics:

• Operating Systems Basics

• IOS Architecture Overview

• Memory Organization

• IOS Processes

• IOS Kernel

• Packet Buffer Management

• Device Drivers

If you were naming the most popular and widely used computer operating systems, which ones would you choose? Most likely, your list would contain names like UNIX, MS-DOS, Microsoft Windows, or even IBM's MVS for mainframes. These are all well-known operating systems—you might even be using one on a computer at home. Now, think for a minute; are there any others? Would your list contain Cisco IOS? No, it probably wouldn't, even though IOS is one of the most widely deployed operating systems in use today.