appn Isr Upper Congestion Threshold

This is the upper threshold for ISR sessions. This attribute and the following one control the node's ISR congestion status. The node state changes from uncongested to congested if the number of ISR sessions exceeds the upper threshold. The node state changes back to uncongested once the number of ISR sessions dips below the lower threshold. To prevent thrashing, the lower threshold should be less than the upper threshold. The upper threshold should be lower than maximumIsrSessions.