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Software Configuration Guide For Cisco 2600 Series, Cisco 3600 Series, and Cisco 3700 Series Routers
OL-1957-03
Chapter 1
Understanding Interface Numbering and Cisco IOS Software Basics
Understanding Cisco IOS Software Basics
Understanding Command Modes
The Cisco IOS user interface is divided into different modes. Each command mode permits you to
configure different components on your router. The commands available at any given time depend on
which mode you are currently in. Entering a question mark (?) at the prompt displays a list of commands
available for each command mode.
Table 1-2
lists the most common command modes.
Timesaver
Each command mode restricts you to a subset of commands. If you are having trouble entering a
command, check the prompt, and enter the question mark (?) for a list of available commands. You
might be in the wrong command mode or using the wrong syntax.
In the following example, notice how the prompt changes after each command to indicate a new
command mode:
Router> enable
Password: <enable password>
Router# configure terminal
Router(config)# interface serial 0/0
Router(config-if)# line 0
Router(config-line)# controller t1 0
Router(config-controller)# exit
Router(config)# exit
Router#
%SYS-5-CONFIG_I: Configured from console by console
The last message is normal and does not indicate an error. Press Return to get the
Router#
prompt.
Table 1-2
Common Command Modes
Command Mode
Access Method
Router Prompt
Displayed
Exit Method
User EXEC
Log in.
Router>
Use the logout
command.
Privileged EXEC
From user EXEC mode,
enter the enable
command.
Router#
To exit to user EXEC
mode, use the disable,
exit, or logout
command.
Global configuration
From the privileged
EXEC mode, enter the
configure terminal
command.
Router (config)#
To exit to privileged
EXEC mode, use the
exit or end command,
or press Ctrl-z.
Interface configuration
From the global
configuration mode,
enter the interface type
number command, such
as interface serial 0/0.
Router (config-if)#
To exit to global
configuration mode, use
the exit command.
To exit directly to
privileged EXEC mode,
press Ctrl-z.
