This object sets the global scope of port isolation on the device: a value of 1 restricts isolation to Layer 2 traffic only, while a value of 2 extends isolation to all traffic, including Layer 3 routed traffic, between isolated ports. An admin sets this depending on whether isolated ports should also be blocked from routing traffic to each other, not just switching it directly. For example, leaving it at the default value of 1 means isolated ports can still route IP traffic to each other through Layer 3, while setting it to 2 would block that too.