This read-write INTEGER sets whether a given port is in protected mode or not-protected mode; protected ports block Layer 2 traffic from other protected ports. An admin isolates devices that should not talk directly to each other, like guest devices on separate ports of the same switch, by marking their ports protected, forcing their traffic up through a router or firewall instead of switching directly port-to-port. For example, an admin connecting several unrelated tenant devices to the same switch would set all their ports to protected(2) so none of them can directly reach each other over the switch's local Layer 2 fabric.