Understanding Command Modes
The command modes available in the traditional Cisco IOS CLI are exactly the same as the command modes available in Cisco IOS XE.
You use the CLI to access Cisco IOS XE software. Because the CLI is divided into many different modes, the commands available to you at any given time depend on the mode that you are currently in. Entering a question mark (? ) at the CLI prompt allows you to obtain a list of commands available for each command mode.
When you log in to the CLI, you are in user EXEC mode. User EXEC mode contains only a limited subset of commands. To have access to all commands, you must enter privileged EXEC mode, normally by using a password. From privileged EXEC mode, you can issue any EXEC command—user or privileged mode—or you can enter global configuration mode. Most EXEC commands are one-time commands. For example, show commands show important status information, and clear commands clear counters or interfaces. The EXEC commands are not saved when the software reboots.
Configuration modes allow you to make changes to the running configuration. If you later save the running configuration to the startup configuration, these changed commands are stored when the software is rebooted. To enter specific configuration modes, you must start at global configuration mode. From global configuration mode, you can enter interface configuration mode and a variety of other modes, such as protocol-specific modes.
ROM monitor mode is a separate mode used when the Cisco IOS XE software cannot load properly. If a valid software image is not found when the software boots or if the configuration file is corrupted at startup, the software might enter ROM monitor mode.
Table 1 describes how to access and exit various common command modes of the Cisco IOS XE software. It also shows examples of the prompts displayed for each mode.
Command Mode |
Access Method |
Prompt |
Exit Method |
---|---|---|---|
User EXEC |
Log in. |
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Use the logout command. |
Privileged EXEC |
From user EXEC mode, use the enable EXEC command. |
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To return to user EXEC mode, use the disable command. |
Global configuration |
From privileged EXEC mode, use the configure terminal privileged EXEC command. |
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To return to privileged EXEC mode from global configuration mode, use the exit or end command. |
Interface configuration |
From global configuration mode, specify an interface using an interface command. |
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To return to global configuration mode, use the exit command. To return to privileged EXEC mode, use the end command. |
Diagnostic |
The router boots up or accesses diagnostic mode in the following scenarios:
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If the IOS process failing is the reason for entering diagnostic mode, the IOS problem must be resolved and the router rebooted to get out of diagnostic mode. If the router is in diagnostic mode because of a transport-map configuration, access the router through another port or using a method that is configured to connect to the Cisco IOS CLI. If the router is accessed through the Route Switch Processor auxiliary port, access the router through another port. Accessing the router through the auxiliary port is not useful for customer purposes anyway. |
ROM monitor |
From privileged EXEC mode, use the reload EXEC command. Press the Break key during the first 60 seconds while the system is booting. |
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To exit ROM monitor mode, use the continue command. |
Universal IOS Image
Starting with XE318SP, there are two flavors of universal images supported on Cisco ASR900 series routers:
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Universal images with the "universalk9" designation in the image name: This universal image offers the strong payload cryptography Cisco IOS feature, the IPSec VPN feature.
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Universal images with the universalk9_npe" designation in the image name: The strong enforcement of encryption capabilities provided by Cisco Software Activation satisfies requirements for the export of encryption capabilities. However, some countries have import requirements that require that the platform does not support any strong crypto functionality such as payload cryptography. To satisfy the import requirements of those countries, the `npe' universal image does not support any strong payload encryption.
Starting with Cisco IOS XE Release 3.18SP, IPsec tunnel is supported only on the Cisco ASR903 and ASR907 routers with payload encryption (PE) images. IPSec requires an IPsec license to function.
Note |
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