VIRL has a useful feature called Build Initial Configurations, which is used when initially setting up a topology. The problem with this feature, is that when it runs, it overwrites existing configuration.

To add to this, the shortcut is right next to the Launch Simulation button (as shown below), which makes it easy to click accidentally. This will not ask for confirmation, it will just overwrite the config.

 

This can be prevented from happening. After building the initial configurations, select all the devices in the topology, click the AutoNetKit tab, and unselect the Auto-generate the configuration based on these attributes checkbox.

 

In some cases, it may be too late to prevent this from happening. Fortunately, the configuration can be rolled back. Next to the Projects tab there is a History tab. From here, select the version to roll back to.

 

However, if you double-click the file, you will get the error We don’t yet support opening topology file revisions.

 

Instead, there are two suitable options. The first is to right-click the revision, and select Compare current with local. This will open a new tab, with the configurations in the two versions side by side.

The second option is to right click the revision and select Get Contents. This will ask for confirmation, and overwrite the current configurations with the revision.