Hello Aaron thanks for response.
But in my scenario i've one Router which is connected to two links.
So for the 3 links i've:
R1 <->R'1
R2 <-->R'2
R1 <-->R'3
where R1 et R2 are in my site and R'1, R'2 and R'3 are in the remote site.
I've added R1 twice as a member (in one i'm using a port dest so i can add again R1 as a member, the port will not be used cause in the VS i'm using all ports and i've disabled translate address and port)
i've 2 transparent monitors on R1, one pinging R'1 and the other is pinging R'3.
So if R'1 is down i've to use R'3 to access to the remote site, but how can i do for that? So the F5 should have to tell to R1 to pass throught R'3 and not R'1.