Basic IOS Commands
This book starts by introducing you to the Cisco Internetwork
Operating System (IOS). The IOS is what runs Cisco routers as
well as some Cisco switches, and it’s what allows you to configure
the devices. You use the command-line interface (CLI) to configure a router, and that is
what I’ll show you in this chapter.
The Cisco router IOS software is responsible for the following important tasks:
Carrying network protocols and functions
Connecting high-speed traffic between devices
Adding security to control access and stop unauthorized network use
Providing scalability for ease of network growth and redundancy
Supplying network reliability for connecting to network resources
You can access the Cisco IOS through the console port of a router, from a modem into the
auxiliary (or aux) port, or even through Telnet and Secure Shell (SSH). Access to the IOS command
line is called an
exec session
.
Once you have attached your console cable (this is a rolled cable, sometimes referred to as
a
rollover cable
) to the router and have started your terminal software, you will be ready to
power on the router. Assuming that this is a new router, it will have no configuration and thus
will need to have, well, everything set up. In this chapter, first I’ll cover the power-on process
of the router, and then I’ll introduce the setup script.
For up-to-the minute updates for this chapter, please see
www.lammle.com