I have a leased line (L/L) to monitor. It has an ISDN Dial Up line as backup. When the L/L is down, the ISDN link will be activated automatically.
At any one time, either one will be up i.e. L/L Up, ISDN Down, L/L Down, ISDN Up.
How do I configure sensor dependency whereby the child sensor (ISDN) will only be monitored when the parent (L/L) sensor is DOWN. When the parent sensor (L/L) goes back UP, the child sensor (ISDN) will be paused.