Archive and Restore Junos OS Configurations
When you activate a new configuration, the Junos OS software automatically keeps an archive of the previous active configuration. This automatic backup mechanism lets you return quickly to a previous configuration using the rollback command. In addition, you can copy configurations from the router to a file server. If needed, you can manually reload and restore the configuration file onto the router.
Rollback to the previous version
To return to a configuration that the Junos OS software has automatically archived, use the rollback command in configuration mode:
 user@host-name# rollback 1 load complete
This rollback command loads the previous configuration but stops short of activating it. If you need to change what’s in the configuration, you can modify it. To see what statements are in the configuration, use the configuration mode show command:
 user@host-name# show
The show command displays all the statements in a configuration one screen at a time. To see the next screen, press Enter or the spacebar.
When you’re ready to activate the configuration, use the commit command:
 user@host-name# commit commit complete
Restore from an older version
In addition to archiving the last version of the configuration, the Junos OS software stores the last 50 active configurations. These files are on the router’s flash and hard disks, so you can restore the configuration saved in a particular file.
Use help with the rollback command to list the full archive:
 user@host-name# rollback ? Possible completions: <[Enter]> Execute this command 0 2007-10-31 12:34:56 PST by fred via cli 1 2007-10-31 12:30:03 PST by fred via cli 2 2007-10-30 14:23:44 PST by fred via cli ... 48 2007-09-03 08:00:03 PST by root via cli 49 2007-09-03 07:45:21 PST by root via cli | Pipe through a command
Pick the configuration by date and time and specify the number in the rollback command to load that configuration:
 user@host-name# rollback 2 load complete
Verify that the change is what you want by using the show command, and then activate it with the commit command:
 user@host-name# show ...  user@host-name# commit commit complete
Archive and restore to/from a server
You can manually archive configuration files by copying them to a file server on your network, following these steps:
Use the Junos OS file copy operational mode command to copy the active configuration, the file juniper.conf.gz, in the router’s /config directory:
user@host-name> file copy /config/juniper.conf.gz server1:/homes/fred/tmp user@server’s password: juniper.conf.gz 100% 2127 2.1KB/s 00:00
Once the file is on the server, rename.
If you need to return to that active configuration, copy it back to the router’s home directory by using the file copy command:
user@host-name> file copy server1:/homes/fred/tmp/juniper.conf.gz-20071031 user@server’s password: juniper.conf.gz-20071031 100% 2127 2.1KB/s 00:00
Look at the files in your home directory to make sure the file arrived safely:
user@host-name> file list juniper.conf.gz-20071031
Change from operational mode to configuration mode by using the configure command, load the configuration file with the load command, and review it with the show command.
Finally, activate the configuration file using the commit command:
user@host-name> configure Entering configuration mode  user@host-name# load juniper.conf.gz-20071031 load complete  user@host-name# show ...  user@host-name# commit commit complete