Big IP facing internet with private IP

Hi all,

our topology is similar to the folowing

The outging triffic is loadbalanced on two links :

for ISP-01 both the egress internet and monitoring traffic use the physical interface and every thing is ok since it has a public IP

for ISP-02 the outgoing interface has a private IP , the egress internet traffic is translated to a pool of IP and routed back from the ISP-02, but the monitoring traffic is generated with the physical IP as a source. whene it reaches the ISP router it is droped and the monitoring fails.

is there a way to force the monitoring to use a pool of IPs ?

thanks a lot