Port Threshold Action is action to take when the number of operational (link up) physical ports is less than tnLagPortThreshold. When a physical port ifOperStatus changes and the number of operational physical ports is less than or equal to tnLagPortThreshold: - when set to down(1), the ifOperStatus for the Link Aggregation Group (tnLagIfIndex) goes to down(2). - when set to dynamicCost(2), the ifOperStatus stays up(2), but dependent protocols such as OSPF are signaled and will adjust their operation (cost) to match the number of physical ports remaining in the Link Aggregation Group. a tnLagDynamicCostOn notification is generated. When a physical port ifOperStatus changes and the number of operational physical ports is greater than tnLagPortThreshold: - when set to down(1), the ifOperStatus for the Link Aggregation Group (tnLagIfIndex) goes to up(1). - when set to dynamicCost(2), the ifOperStatus stays up(2), but dependent protocols such as OSPF are signaled and will adjust their operation (cost) to be the value as configured. a tnLagDynamicCostOff notification is generated. Regardless of the setting of this object, when the number of operational physical ports goes to zero, the Link Aggregation Group's ifOperStatus goes to down.