System Reliability Equation = 
- RHBA11·RServer1·RSwitch1·RSwitch2·RController1·RController2·RHBA22·RServer2·RHBA12·RHBA21 
+ RHBA11·RServer1·RSwitch1·RSwitch2·RController1·RController2·RHBA22·RServer2·RHBA12 
+RHBA11·RServer1·RSwitch1·RSwitch2·RController1·RController2·RHBA22·RServer2·RHBA21 
+ RHBA11·RServer1·RSwitch1·RSwitch2·RController1·RController2·RServer2·RHBA12·RHBA21 
+ RServer1·RSwitch1·RSwitch2·RController1·RController2·RHBA22·RServer2·RHBA12·RHBA21 
- RHBA11·RServer1·RSwitch1·RSwitch2·RController1·RController2·RHBA22·RServer2 
- RServer1·RSwitch1·RSwitch2·RController1·RController2·RServer2·RHBA12·RHBA21
- RHBA11·RServer1·RSwitch1·RSwitch2·RController1·RController2·RHBA12
- RSwitch1·RSwitch2·RController1·RController2·RHBA22·RServer2·RHBA21
- RHBA11·RServer1·RSwitch1·RController1·RServer2·RHBA21 
- RServer1·RSwitch2·RController2·RHBA22·RServer2·RHBA12 
+ RHBA11·RServer1·RSwitch1·RController1 
+ RServer1·RSwitch2·RController2·RHBA12 
+ RSwitch1·RController1·RServer2·RHBA21 
+ RSwitch2·RController2·RHBA22·RServer2

System cdf = 1-System Reliability Equation

Where each R is the reliability (1-cdf) function of the item. As an example, RServer2 is the reliability function of Server 2.