Cisco ASR 901 User Manual

1-4
Cisco ASR 901 Aggregation Services Router Command Reference Guide
OL-26031-07
Chapter 1 Using Command-Line Interface
Understanding Command Modes
Understanding Command Modes
The Cisco ASR 901 series router Cisco IOS user interface is divided into many different modes. The
commands that are available to you depend on which mode you are currently in. You can obtain a list of
commands that are available for each command mode by entering a question mark (?) at the system
prompt.
When you start a session on the Cisco ASR 901 series router, you begin in user mode, often called EXEC
mode. Only a limited subset of the commands are available in EXEC mode. In order to have access to
all commands, you must enter privileged EXEC mode. Normally, you must enter a password to enter
privileged EXEC mode. From privileged EXEC mode, you can enter any EXEC command or enter global
configuration mode. Most EXEC commands are one-time commands, such as show commands, which
show the current status of a given item, and clear commands, which clear counters or interfaces. The
EXEC commands are not saved across reboots of the Cisco ASR 901 series router.
The configuration modes allow you to make changes to the running configuration. If you later save the
configuration, these commands are stored across Cisco ASR 901 series router reboots. In order to get to
the various configuration modes, you must start at global configuration mode where you can enter
interface configuration mode, subinterface configuration mode, and a variety of protocol-specific modes.
ROM-monitor mode is a separate mode that is used when the Cisco ASR 901 series router cannot boot
properly. If your Cisco ASR 901 series router or access server does not find a valid system image when
it is booting, or if its configuration file is corrupted at startup, the system might enter ROM-monitor
mode.
Table 1-3 provides a summary of the main command modes.
For more information on command modes, refer to the “Using the Command Line Interface” chapter of
the Configuration Fundamentals Configuration Guide.
Table 1-3 Summary of Main Command Modes
Command
Mode Access Method Prompt Exit Method
User EXEC Log in.
Router>
Use the logout command.
Privileged
EXEC
From user EXEC mode,
enter the enable EXEC
command.
Router#
To exit to user EXEC mode, enter the disable
command.
To enter global configuration mode, enter the
configure terminal privileged EXEC command.
Global
configuration
From privileged EXEC
mode, enter the
configure terminal
privileged EXEC
command.
Router(config)#
To exit to privileged EXEC mode, enter the exit or
end command or press Ctrl-Z.
To enter interface configuration mode, enter an
interface configuration command.
Interface
configuration
From global
configuration mode,
enter by specifying an
interface with an
interface command.
Router(config-if)#
To exit to global configuration mode, enter the exit
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.

Cisco ASR 901 Specifications

General

Brand	Cisco
Model	ASR 901
Category	Network Router
Language	English