Cisco Router 860, 880 Series User Manual

							 
PART 5
Reference Information (Appendixes) 
						

							 
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APPENDIXA
Cisco IOS Software Basic Skills
Understanding how to use Cisco IOS software can save you time when you are configuring your router. 
This appendix contains the following sections which provide basic information:
 Configuring the Router from a PC, page A-1
 Understanding Command Modes, page A-2
 Getting Help, page A-4
 Enable Secret Passwords and Enable Passwords, page A-5
 Entering Global Configuration Mode, page A-5
 Using Commands, page A-6
 Saving Configuration Changes, page A-7
 Summary, page A-7
 Where to Go Next, page A-7
If you are already familiar with Cisco IOS software, go to one of the following chapters:
 Chapter 3, “Basic Router Configuration” 
 Chapter 18, “Deployment Scenarios”
Configuring the Router from a PC
You can configure your router from a PC that is connected through the console port by using terminal 
emulation software. The PC uses this software to send commands to your router. 
Ta b l e A-1 lists some 
common types of terminal emulation software that you can use, depending on the operating system that 
you are running. 
						

							 
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Appendix A      Cisco IOS Software Basic Skills
  Understanding Command Modes
You can use the terminal emulation software to change settings for the router that is connected to the PC. 
Configure the software to the following standard VT-100 emulation settings so that your PC can 
communicate with your router:
 9600 baud
 8 data bits
 No parity
 1 stop bit
 No flow control
These settings should match the default settings of your router. To change the router baud, data bits, 
parity, or stop bits settings, you must reconfigure parameters in the ROM monitor. For more information, 
see 
Appendix C, “ROM Monitor.” To change the router flow control setting, use the flowcontrol 
command in global configuration mode.
For information on how to enter global configuration mode so that you can configure your router, see 
the 
“Entering Global Configuration Mode” section later in this chapter.
Understanding Command Modes
This section describes the Cisco IOS command mode structure. Each command mode supports specific 
Cisco IOS commands. For example, you can use the interface type number command only from global 
configuration mode.
The following Cisco IOS command modes are hierarchical. When you begin a router session, you are in 
user EXEC mode.
 User EXEC
 Privileged EXEC
 Global configuration
Ta b l e A-2 lists the command modes that are used in this guide, describes how to access each mode, 
shows the prompt for each mode, and explains how to exit to a mode or enter another mode. Because 
each mode configures different router elements, you might need to enter and exit modes frequently. You 
can see a list of available commands for a particular mode by entering a question mark (?) at the prompt. 
For a description of each command, including syntax, see the Cisco IOS Release 12.3 documentation set.
Ta b l e A-1 Types of Terminal Emulation Software
PC Operating SystemTerminal Emulation Software
Windows 95, Windows 98, Windows 2000, 
Windows
 NT, Windows XP
HyperTerm (included with Windows software), 
ProComm Plus
Windows 3.1 Terminal (included with Windows software) 
Macintosh ProComm, VersaTerm 
						

							 
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  Understanding Command Modes
Ta b l e A-2 Command Modes Summary 
ModeAccess MethodPromptMode Exit and EntranceAbout This Mode
User EXECBegin a session with 
your router.Router>To exit a router session, enter 
the logout command. Use this mode to:
 Change terminal settings.
 Perform basic tests.
 Display system information.
Privileged 
EXECEnter the enable 
command from user 
EXEC mode.Router# 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 router 
operating parameters. 
 Perform the verification steps 
shown in this guide.
To prevent unauthorized changes 
to your router configuration, 
protect access to this mode by 
using a password as described in 
the 
“Enable Secret Passwords and 
Enable Passwords” procedure on 
page A-5.
Global 
configurationEnter the configure 
command from 
privileged EXEC 
mode.Router 
(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 
router globally.
From this mode you can access the 
following modes:
 Interface configuration
 Router configuration
 Line configuration
Interface 
configurationEnter the interface 
command (with a 
specific interface, such 
as interface atm 0) 
from global 
configuration mode.Router 
(config-if)# To exit to global 
configuration mode, 
enter the exit command.
 To exit to privileged 
EXEC mode, enter the 
end command, or press 
Ctrl-Z. 
 To enter subinterface 
configuration mode, 
specify a subinterface by 
using the interface 
command.
Use this mode to configure 
parameters for the router Ethernet 
and serial interfaces or 
subinterfaces. 
						

							 
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Appendix A      Cisco IOS Software Basic Skills
  Getting Help
Getting Help
You can use the question mark (?) and arrow keys to help you enter commands.
For a list of available commands for a prticular command mode, enter a question mark:
Router> ?
access-enable Create a temporary access-list entry
access-profile Apply user-profile to interfaceclear Reset functions
.
..
To complete a command, enter a few known characters followed by a question mark (with no space):
Router> sh?
* s=show set show slip systat
For a list of command variables, enter the command followed by a space and a question mark:
Router> show ?
.
..
clock Display the system clock
dialer Dialer parameters and statisticsexception exception information
.
..
To redisplay a command that you previously entered, press the Up Arrow key. You can continue to press 
the Up Arrow key for more commands.
Router 
configurationEnter one of the router 
commands followed by 
the appropriate 
keyword—for example 
router rip—from 
global configuration 
mode.Router 
(config- 
router)# To exit to global 
configuration mode, 
enter the exit command.
 To exit to privileged 
EXEC mode, enter the 
end command, or press 
Ctrl-Z. 
Use this mode to configure an IP 
routing protocol.
Line 
configurationEnter the line 
command with the 
desired line number 
and optional line type, 
for example, line 0, 
from global 
configuration mode.Router 
(config- 
line)# To exit to global 
configuration mode, 
enter the exit command.
 To exit to privileged 
EXEC mode, enter the 
end command, or press 
Ctrl-Z.
Use this mode to configure 
parameters for the terminal line.
Table A-2 Command Modes Summary (continued)
Mode Access Method Prompt Mode Exit and Entrance About This Mode 
						

							 
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  Enable Secret Passwords and Enable Passwords
Enable Secret Passwords and Enable Passwords
By default, the router ships without password protection. Because many privileged EXEC commands are 
used to set operating parameters, you should password-protect these commands to prevent unauthorized 
use. 
You can use two commands to do this:
 enable secret password—A very secure, encrypted password.
 enable password—A less secure, unencrypted local password.
Both the enable and enable secret passwords control access to various privilege levels (0 to 15). The 
enable password is intended for local use and is thus unencrypted. The enable secret password is 
intended for network use; that is, in environments where the password crosses the network or is stored 
on a TFTP server. You must enter an enable secret or enable password with a privilege level of 1 to gain 
access to privileged EXEC mode commands.
For maximum security, the passwords should be different. If you enter the same password for both during 
the setup process, your router accepts the passwords, but warns you that they should be different. 
An enable secret password can contain from 1 to 25 uppercase and lowercase alphanumeric characters. 
An enable password can contain any number of uppercase and lowercase alphanumeric characters. In 
both cases, a number cannot be the first character. Spaces are also valid password characters; for 
example, two words is a valid password. Leading spaces are ignored; trailing spaces are recognized. 
Entering Global Configuration Mode
To make any configuration changes to your router, you must be in global configuration mode. This 
section describes how to enter global configuration mode while using a terminal or PC that is connected 
to your router console port.
To enter global configuration mode, follow these steps:
Step 1After your router boots up, enter the enable or enable secret command:
Router> enable
Step 2If you have configured your router with an enable password, enter it when you are prompted. 
The enable password does not appear on the screen when you enter it. This example shows how to enter 
privileged EXEC mode:
Password: enable_passwordRouter#
Privileged EXEC mode is indicated by the pound sign (#) in the prompt. You can now make changes to 
your router configuration.
Step 3Enter the configure terminal command to enter global configuration mode: 
Router# configure terminal
Router(config)#
You can now make changes to your router configuration. 
						

							 
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Appendix A      Cisco IOS Software Basic Skills
  Using Commands
Using Commands
This section provides some tips about entering Cisco IOS commands at the command-line interface 
(CLI).
Abbreviating Commands
You only have to enter enough characters for the router to recognize the command as unique. This 
example shows how to enter the show version command:
Router # sh v 
Undoing Commands
If you want to disable a feature or undo a command that you entered, you can enter the keyword no 
before most commands; for example, no ip routing. 
Command-Line Error Messages
Ta b l e A-3 lists some error messages that you might encounter while using the CLI to configure your 
router.
Ta b l e A-3 Common CLI Error Messages 
Error MessageMeaningHow to Get Help
% Ambiguous command:  show conYou did not enter enough 
characters for your router to 
recognize the command.Reenter 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 the 
keywords or values required by 
this command.Reenter 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 the commands that 
are available in this particular 
command mode. 
						

							 
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  Saving Configuration Changes
Saving Configuration Changes
You must enter the copy running-config startup-config command to save your configuration changes 
toNVRAM so that they are not lost if there is a system reload or power outage. This example shows how 
to use this command to save your changes:
Router# copy running-config startup-configDestination filename [startup-config]?
Press Return to accept the default destination filename startup-config, or enter your desired destination 
filename and press Return.
It might take a minute or two to save the configuration to NVRAM. After the configuration has been 
saved, the following message appears:
Building configuration...
Router#
Summary
Now that you have reviewed some Cisco IOS software basics, you can begin to configure your router. 
Remember:
 You can use the question mark (?) and arrow keys to help you enter commands.
 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. 
 To disable a feature, enter the keyword no before the command; for example, no ip routing.
 Save your configuration changes to NVRAM so that they are not lost if there is a system reload or 
power outage.
Where to Go Next
To configure your router, go to Chapter 3, “Basic Router Configuration,” and Chapter 18, “Deployment 
Scenarios.” 
						

							 
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  Where to Go Next