This toggles whether the switch raises ATM OAM alarm traps for any circuit on this logical port that goes down, per the object's description. An admin managing a port with expected intermittent circuit flaps would set this to disabled(2) to suppress alarm floods, while leaving production trunks at enabled(1) so downstream circuit failures are reported immediately. For example, disabling it on a lightly-used lport carrying 20 provisioned test PVCs prevents 20 spurious 'circuit down' OAM alarms from flooding the NMS.