What is the function of a Layer guard?
The layer guard feature allows you to set a condition by which the whole layer is evaluated or not. If the conditions set in the layer guard are met then the rest of the layer is evaluated, otherwise policy evaluation skips this layer and goes onto the next layer.
When added, the layer guard is a single rule table that appears above the selected layer. The layer guard rule contains all of the columns available in the layer except for the Action and Track columns. These columns are not required because the rule itself does not invoke an action other than allowing or not allowing policy evaluation for the entire layer. All of the objects valid in the available columns are selectable and configurable in the layer guard rule, just as they are in the layer.
You cannot add a layer guard rule until you have created other policy layer rules.