Configure Replace

Cisco has the functionality to do an in-place replacement of the running config, without requiring a device reload. This is similar to the rollback functionality seen on Juniper devices. This function automatically swaps the config, automatically adding/removing any differences encountered. This is different than just doing "copy start-config running-config" as that will merge the changes, and won't delete anything.

configure replace <filename>

Example

ROUTER#$configure replace tftp://10.10.10.5/ROUTER-autoarchive-Jun--9-15:09:56.137-EDT-0
This will apply all necessary additions and deletions
to replace the current running configuration with the
contents of the specified configuration file, which is
assumed to be a complete configuration, not a partial
configuration. Enter Y if you are sure you want to proceed. ? [no]: y
Loading ROUTER-autoarchive-Jun--9-15:09:56.137-EDT-0 from 10.10.10.5 (via Ethernet0): !
[OK - 7029 bytes]

Total number of passes: 1
Rollback Done

You can also use this to roll back to the startup config:

configure replace nvram:startup-config