Cisco IE 4000, Software Configuration Manual

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1011
Working with the Cisco IOS File System, Configuration Files, and Software Images
Working with Configuration Files
Rolling Back a Configuration
You can also use the configure replace command to roll back changes that were made since the previous configuration
was saved. Instead of basing the rollback operation on a specific set of changes that were applied, the configuration
rollback capability reverts to a specific configuration based on a saved configuration file.
If you want the configuration rollback capability, you must first save the running configuration before making any
configuration changes. Then, after entering configuration changes, you can use that saved configuration file to roll back
the changes by using the
configure replace target-url command.
You can specify any saved configuration file as the rollback configuration. You are not limited to a fixed number of
rollbacks, as is the case in some rollback models.
Configuration Guidelines
Follow these guidelines when configuring and performing configuration replacement and rollback:

Make sure that the switch has free memory larger than the combined size of the two configuration files (the running
configuration and the saved replacement configuration). Otherwise, the configuration replacement operation fails.

Make sure that the switch also has sufficient free memory to execute the configuration replacement or rollback
configuration commands.

Certain configuration commands, such as those pertaining to physical components of a networking device (for
example, physical interfaces), cannot be added or removed from the running configuration.
— A configuration replacement operation cannot remove the interface interface-id command line from the running
configuration if that interface is physically present on the device.
— The interface interface-id command line cannot be added to the running configuration if no such interface is
physically present on the device.

When using the configure replace command, you must specify a saved configuration as the replacement
configuration file for the running configuration. The replacement file must be a complete configuration generated by
a Cisco IOS device (for example, a configuration generated by the
copy running-config destination-url command).
Note: If you generate the replacement configuration file externally, it must comply with the format of files generated by
Cisco IOS devices.
Configuring the Configuration Archive
Using the configure replace command with the configuration archive and with the archive config command is optional
but offers significant benefit for configuration rollback scenarios. Before using the archive config command , you must
first configure the configuration archive. Starting in privileged EXEC mode, follow these steps to configure the
configuration archive:
Command Purpose
1. configure terminal Enters global configuration mode.
2. archive Enters archive configuration mode.
3. path url Specifies the location and filename prefix for the files in the configuration
archive.