ICMP preferred route

We have an LC v.9.x

 

 

We have 2 ISP's.

 

 

We are trying to monitor ISP-1 by sending pings to it from our monitoring software. At time the LC will send the ping request thru ISP-2, in which it will return a ping time out. This will alert the monitoring software that ISP1 is down (false negative).

 

 

Is there a way that an iRule can be written to eliminate this? I only want this iRule to effect ping requests to ISP-1's router. All other traffic should be handle as usual.

 

 

Is there a better way to monitor this? SNMP to my monitoring software?