Using the Command-Line Interface

Overview

Understanding Command Modes

Entering Configuration Mode

Using Commands

Undoing Commands

Understanding Command-Line Error Messages

Getting Help

Saving the Configuration

Where to Go Next

Using the Command-Line Interface

This chapter describes the basic IOS concepts you need to know before you begin using the command-line interface (CLI) to configure the different components of your system and contains the following sections:

Understanding these concepts saves you time when you are configuring your system. If you have never used IOS software or you need a refresher, take a few minutes to read this chapter before you proceed to the next chapter.

If you are already familiar with IOS software, you can proceed to the configuration chapter that is appropriate for your system.

Overview

The Cisco ICS 7750 is supported by IOS software and supports the following software images:

Cisco IOS Release 12.0(5.2)XU for the system switch processor (SSP) card.
Cisco IOS Release 12.1(4)T for the multiservice route processor (MRP) card.

This document lists some of the commands that are necessary for configuring the SSP and the MRP cards. For an entire list of commands supported by the Cisco ICS 7750, refer to the Cisco IOS Release 12.0 Command Summary on the Documentation Home Page.

For detailed configuration tasks, refer to the Cisco ICS 7750 Software Configuration Guide that came with your system.

Understanding Command Modes

This section describes the IOS command mode structure. Each command mode supports specific IOS commands. For example, the interface type_number command is used only when in global configuration mode.

Use the following IOS command modes when configuring the scenarios described in this document:

User EXEC
Privileged EXEC
Global configuration
Interface configuration
Router configuration
Line configuration

Note Throughout the examples in this guide, there are steps for verifying your system configuration by using different IOS commands. If you plan to use these verification steps, you must understand how to change from one command mode to another, as summarized in Table 1-1.

Table 1-1 lists the command modes that are used in this guide, explains how to access each mode, describes the prompt you see in that mode, and explains how to exit that mode. The examples in the table use the host name 7750. This host name could be anything as it is used only to provide the prompt.

Table 1-1: Comma nd Modes Summary

Mode Access Method Prompt Exit Method About This Mode¹

User EXEC

Begin a session with your system.

7750>

Enter the logout command.

Use this mode to:

Change terminal settings

Perform basic tests

Display system information

Privileged EXEC

Enter the enable command while in user EXEC mode.

7750>

To exit to user EXEC mode, enter the disable command.

To enter global configuration mode, enter the configure command.

Use this mode to:

Configure your system operating parameters

Perform the verification steps shown in this guide

You should configure your system with an enable password to prevent anyone from making unauthorized changes to the system configuration.

Global configuration

Enter the configure command while in privileged EXEC mode.

7750(config)#

To exit to privileged EXEC mode, enter the exit or end command, or press Ctrl-Z.

To enter interface configuration mode, enter the interface command.

Use this mode to configure parameters that apply to your system as a whole.

Interface configuration

Enter the interface command (with a specific interface) while in the global configuration mode. For example, interface serial 0/0.

7750(config-if)#

To exit to global configuration mode, enter the end command.

To exit to privileged EXEC mode, enter the exit command, or press Ctrl-Z.

To enter subinterface configuration mode, specify a subinterface with the interface command.

Use this mode to configure parameters for the various LAN and WAN interfaces of your system, including:

Ethernet interface

Serial interface

ISDN interface

Router configuration

Enter the router command followed by the appropriate keyword while in global configuration mode. For example, router igrp 200

7750(config-

router)#

To exit to global configuration mode, enter the end command.

To exit to privileged EXEC mode, enter the exit command, or press Ctrl-Z.

Use this mode to configure an IP routing protocol.

Line configuration

Specify a line with the line vty command while in the global configuration mode. For example, line vty 0

7750(config-line)#

To exit to global configuration mode, enter the exit command.

To enter privileged EXEC mode, enter the end command, or press Ctrl-Z.

Use this mode to configure parameters for the terminal line.

¹For any of the modes, you can see a comprehensive list of the available commands by entering a question mark (?) at the prompt.

Mode	Access Method	Prompt	Exit Method	About This Mode¹
User EXEC	Begin a session with your system.	7750>	Enter the logout command.	Use this mode to: Change terminal settings Perform basic tests Display system information
Privileged EXEC	Enter the enable command while in user EXEC mode.	7750>	To exit to user EXEC mode, enter the disable command. To enter global configuration mode, enter the configure command.	Use this mode to: Configure your system operating parameters Perform the verification steps shown in this guide You should configure your system with an enable password to prevent anyone from making unauthorized changes to the system configuration.
Global configuration	Enter the configure command while in privileged EXEC mode.	7750(config)#	To exit to privileged EXEC mode, enter the exit or end command, or press Ctrl-Z. To enter interface configuration mode, enter the interface command.	Use this mode to configure parameters that apply to your system as a whole.
Interface configuration	Enter the interface command (with a specific interface) while in the global configuration mode. For example, interface serial 0/0.	7750(config-if)#	To exit to global configuration mode, enter the end command. To exit to privileged EXEC mode, enter the exit command, or press Ctrl-Z. To enter subinterface configuration mode, specify a subinterface with the interface command.	Use this mode to configure parameters for the various LAN and WAN interfaces of your system, including: Ethernet interface Serial interface ISDN interface
Router configuration	Enter the router command followed by the appropriate keyword while in global configuration mode. For example, router igrp 200	7750(config- router)#	To exit to global configuration mode, enter the end command. To exit to privileged EXEC mode, enter the exit command, or press Ctrl-Z.	Use this mode to configure an IP routing protocol.
Line configuration	Specify a line with the line vty command while in the global configuration mode. For example, line vty 0	7750(config-line)#	To exit to global configuration mode, enter the exit command. To enter privileged EXEC mode, enter the end command, or press Ctrl-Z.	Use this mode to configure parameters for the terminal line.

Entering Configuration Mode

To make any configuration changes to your system, you must be in configuration mode (also known as Privileged Exec mode). This section describes how to enter configuration mode while using a terminal or PC that is connected to your system CONSOLE port.

Follow these steps to enter configuration mode:

Step 1 Connect a terminal or PC to the router.

To configure the router with a PC, the PC must have some type of terminal emulation software installed. The software should be configured with the following parameters: 9600 baud, 8 data bits, no parity, 1 stop bit.

Step 2 Power up the system.

Step 3 If the current configuration is no longer valid (for instance, because you added an interface), after about 1 minute you will see the following prompt:

Would you like to enter the initial configuration dialog? [yes]:

Do not use the yes default. You need to enter no to enter the normal operating mode of the router.

Note If the current configuration is valid, you enter the normal operating mode automatically.

Step 4 At the user EXEC prompt (Router>), enter enable and the password to enter enable mode:

Router> enable

Password:

Configuration changes can be made only in enable mode. The prompt changes to the privileged EXEC (enable) prompt (Router#):

Router#

Step 5 Enter the following command to enter global configuration mode:

Router# config terminal

Router(config)#

Step 6 If you have not configured the system before or want to change the configuration, you need to configure global parameters, passwords, network management, and routing protocols. In this example, IP routing, AppleTalk routing, and IPX routing are all enabled:

Router(config)# ip routing

Router(config)# appletalk routing

Router(config)# ipx routing

For complete information about the global configuration commands and about configuring LAN and WAN interfaces on your system, refer to the Cisco IOS configuration guides and command references.

Using Commands

This section provides tips about entering Cisco IOS commands at the CLI.

Undoing Commands

If you want to disable a feature or undo a command you entered, you can enter the keyword no before most commands: for example, no ip routing.

Understanding Command-Line Error Messages

Table 1-2 lists some error messages that you might encounter while using the CLI to configure your system.

Table 1-2: Common CLI Error Messages

Error Message Meaning How to Get Help

% Ambiguous command:show con
You did not enter enough characters for your system to recognize the command.

Re-enter the command followed by a question mark (?) with no space between the command and the question mark.

The possible keywords that you can enter with the command are displayed.

% Incomplete command.
You did not enter all of the keywords or values required by this command.

Re-enter the command followed by a question mark (?) with no space between the command and the question mark.

The possible keywords that you can enter with the command are displayed.

% Invalid input detected at `^' marker.
You entered the command incorrectly. The error occurred where the caret mark (^) appears.

Enter a question mark (?) to display all of the commands that are available in this command mode.

Error Message	Meaning	How to Get Help
% Ambiguous command:show con	You did not enter enough characters for your system to recognize the command.	Re-enter the command followed by a question mark (?) with no space between the command and the question mark. The possible keywords that you can enter with the command are displayed.
% Incomplete command.	You did not enter all of the keywords or values required by this command.	Re-enter the command followed by a question mark (?) with no space between the command and the question mark. The possible keywords that you can enter with the command are displayed.
% Invalid input detected at `^' marker.	You entered the command incorrectly. The error occurred where the caret mark (^) appears.	Enter a question mark (?) to display all of the commands that are available in this command mode.

Getting Help

You can use the question mark (?) and arrow keys to help you enter commands. Here are several ways to get help while in any command mode:

Display all commands:

: Enter a question mark to list the commands that are available in the current mode. You can restrict the list to all commands starting with a specific letter by entering that letter, followed by a question mark (no space):

7750(config-if)# s?
  shutdown
  snapshot
  snmp
  standby

Display available keywords:

: Enter a command, a space, and a question mark to list the available keywords (and a short definition of the keywords) that can be used with the command:

7750(config-if)# snapshot ?
  client Enable client control of Snapshot routing

  server Send routing updates out this link when updates are received

Display value ranges:

: Enter a command, a keyword, a space, and a question mark to list the range of values (and a short definition of the values) that you can enter with the command:

7750(config-if)# snapshot client ?
  <5-1000> duration, in minutes, of each active period

Abbreviate commands:

: Enter a few known characters to have the system complete the command. In this example, the command is show hosts:

7750(config-if)> sh ho
Default domain is not set
Name/address lookup uses domain service
Name servers are 255.255.255.25

To redisplay a command you previously entered, press the up arrow key. You can continue to press the up arrow key to see all commands in the reverse order they were entered.

Saving the Configuration

You must save the new configuration to nonvolatile RAM (NVRAM) periodically during the configuration process, and also when you finish configuring the system so that they are not lost if there is a system reload or power outage.

IOS software uses two configuration files: startup config and running config. The startup-config file is a backup file that has all of the information you specified about the system interfaces and is used by the system on the next restart. The running-config file has the current operating configuration with the changes you have just made. You can make any changes to the running-config file; however, these changes will be lost when the system powers down. To make these changes permanent, copy the running-config file to the startup-config file stored in NVRAM.

Follow these steps to write the new configuration to NVRAM:

Step 1 Exit configuration mode, and return to the enable prompt by pressing Ctrl-Z or entering the end global configuration command.

Step 2 To see the startup configuration stored in NVRAM, enter the following command at the enable prompt:

7750# show startup-config

Step 3 To see the operating configuration, including any changes you have just made, enter the following command:

7750# show running-config

Step 4 To write your changes to NVRAM and make them permanent, enter the following command:

7750# copy running-config startup-config

Building configuration. . .
[OK]
7750#

The system is now configured to boot in the new configuration.

Where to Go Next

Remember the following guidelines:

You can use the question mark (?) and arrow keys to list the commands that are available in the current mode.
Each command mode restricts you to a set of commands. If you are having difficulty entering a command, check the prompt, and then enter the question mark (?) for a list of available commands. You might be in the wrong command mode or using the wrong syntax.
If you want to disable a feature, enter the keyword no before the command; for example, no ip routing.
Save your configuration changes so that they are not lost if there is a system reload or power outage.

Now that you have learned IOS CLI software basics, proceed to any one of the configuration chapters to begin configuring different components of your system.

Table of Contents

Using the Command-Line Interface