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Operating and Configuring a Cisco IOS Device

   

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Operating and Configuring a Cisco IOS Device

  

 

Basic Operation of Cisco IOS Software

  

 

What Happens When You Start a Switch

  

 

Keyboard Help in Switch Command-Line Interface

  

 

Commands to Get Basic Switch Information

  

 

Configuring the Switch from the Command Line

  

 

What Happens When You Start a Router

  

 

Keyboard Help in Router Command-Line Interface

  

 

Commands to Get Basic Router Information

  

 

Configuring a Router from the Command Line

  

 

Summary

  

 

Review Questions

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Interconnecting Cisco Network Devices

From: Interconnecting Cisco Network Devices
Author: Stephen McQuerry
Publisher: Cisco Press (53)
More Information

3. Operating and Configuring a Cisco IOS Device

Upon completion of this chapter, you will be able to perform the following tasks:

  • Start the Cisco switch and router and describe and recognize a normal boot sequence.

  • Provide an initial configuration for the switch and apply a basic initial configuration to the router using the setup facility.

  • Describe and use the command modes to interact with the Cisco IOS software.

  • Use the online help facilities associated with the command-line interface to modify the configuration of a device.

  • Use the Cisco switch and router show commands to determine fundamental operational characteristics of the switch.

In this chapter, you will learn the process of starting and configuring a Cisco switch and router. You will also learn to perform tasks using the Cisco IOS software user interface. In order to install Cisco devices in your network, you need to understand the startup of the Cisco switch and router and describe and recognize a normal boot sequence. It will also be important to provide an initial configuration for the switch and apply a basic initial configuration to the router using the setup facility.

After you have established an initial setup, you will need to describe and use the command modes to interact with the Cisco IOS software. Learn to use the online help facilities associated with the command-line interface to modify the configuration of a device. Finally, you will need to use the Cisco switch and router show commands to determine fundamental operational characteristics of the switch.

Basic Operation of Cisco IOS Software

Cisco's internetwork operating system (IOS) software platform is implemented on the varied hardware discussed in this book. IOS software delivers network services and enables networked applications. It is the embedded software architecture in all of the Cisco routers, and it is also the operating system of the Catalyst 1900 enterprise series switches.

Cisco IOS enables network services in these products, including the following:

  • Features to carry the chosen network protocols and functions

  • Connectivity to provide high-speed traffic between devices

  • Security to control access and discourage unauthorized network use

  • Scalability to add interfaces and capability as the need for networking grows

  • Reliability to ensure dependable access to networked resources

A Cisco IOS command-line interface (CLI) can be accessed through a console connection, modem connection, or Telnet session. Regardless of which connection method is used, access to the IOS command-line interface is generally referred to as an EXEC session.

You will learn to use the Cisco IOS software to communicate the configuration details for the switches and routers discussed in this book. The purpose here is to help facilitate the knowledge transfer for configuring Cisco devices. Back on the job, you can use this knowledge to support a configuration that will reflect the policy of functions and authorizations that are required by your organization.

Protocol addresses and parameters will be guided by the objectives of this book and will be structured to help you understand internetworking. Back on the job, address and related parameters will reflect legal addressing and the protocol requirements of your company.

When you start the Catalyst switch for the first time, it uses an initial configuration with default settings.

When you start the Cisco router for the first time, it does not have an initial configuration. The router software will prompt you for a minimum of details using an optional dialog called Setup.

You will set up a minimum device configuration for the router and the switch in this chapter. Changes to these minimum or default configurations constitute much of your network administrator tasks. Most of these configuration changes will occur later in this book.

Operations upon Router/Switch Startup

When the Catalyst switch or Cisco router starts up, three main operations are performed on the networking device:

  1. The device finds the hardware and performs hardware-checking routines. A term often used to describe this initial set of routines is power-on self test (POST).

  2. After the hardware has been shown to be in good working order, the devices perform system startup routines. These routines initiate the switch or router by locating and loading the operating system software.

  3. After the operating system is loaded, the devices try to find and apply software configuration settings that establish the details needed for network operation.

There is typically a sequence of fallback routines that provide software startup alternatives if needed.

In the next several pages of this chapter, you will learn about and practice using these three main operations. You will start up the switch first, and then the router.

Router/Switch Configuration Locations

The switch and the router can be configured from many locations:

  • Upon initial installation, the network administrator typically configures the networking devices from the console terminal, which is connected via the console port.

  • If the administrator is supporting remote devices, a local modem connection at the device's auxiliary port permits the administrator to configure the network devices.

  • For selected routers and switches, a CD-ROM can provide a rapid configuration application, such as Cisco Fast Step, to make the most simple configuration tasks easier to accomplish.

After initial startup, there are additional external sources for software that connect to device interfaces:

  • Devices with established IP addresses can allow Telnet connections for configuration work.

  • Download a configuration file from a Trivial File Transfer Protocol (TFTP) server.

  • Configure the device via a Hypertext Transfer Protocol (HTTP) browser.

NOTE

All three of the methods just mentioned assume an active IP configuration and network connectivity to the device.

IOS Command Modes

Cisco IOS software uses a command-line interface as its traditional console environment. Although Cisco IOS software is a core technology that extends across many products, Cisco IOS operation details vary on different internetworking devices.

To enter commands into the user interface, you type your entries within one of several console command modes. Each command mode is indicated by a distinctive prompt.

Cisco IOS software uses a hierarchy of commands in its command-mode structure. Each command mode supports specific Cisco IOS commands related to a type of operation on the device.

As a security feature, Cisco IOS separates EXEC sessions into two different default access levels: user EXEC level and privileged EXEC level.

User EXEC level lets you access only a limited number of basic monitoring commands.

Privileged EXEC level lets you access all router commands (for example, configuration and management). It can be password-protected to allow only authorized users to configure or maintain the router.

The Enter key instructs the device to parse and execute the command.

For example, when an EXEC session is started, the router will display a hostname> prompt. The right arrow (>) in the prompt indicates that the router is at the user EXEC level.

The user EXEC level does not contain any commands that might allow the user to control the operation of the router (for example, reload or configure).

To list the commands available at the user EXEC level, type a question mark (?) at the hostname> prompt. (This feature is referred to as context-sensitive help.)

Critical commands (for example, configuration, management, and debugging) require that the user be at the privileged EXEC level. Privileged EXEC mode provides the user with a detailed examination of a switch or router.

To change to the privileged EXEC level, type enable at the hostname> prompt. If an enable password or enable secret password is configured, the switch or router will then prompt you for that password.

When the correct enable password is entered, the switch or router prompt will change to hostname#, indicating that the user is now at the privileged EXEC level.

Typing a question mark (?) at the privileged EXEC level will reveal many more command options than those available at the user EXEC level. To return to the user EXEC level, type disable at the hostname# prompt.

   

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