Monitoring issues

hi everyone,

 

I've got an issue: I 've a website with a virtual server (VS-A) connected towards 2 nodes (N-A1 & N-A2). those nodes are making a connection towards another virtual serves (VS-B) with again 2 nodes (N-B1 & N-B2).

 

When VS-B goes down, the VS-A stays up but the application running on the web gaves functional errors as VS-B is down.

 

So my question is how can I set VS-A down when his pool is down OR when VS-B is down.

 

Thanks for the idea's :-D