GTM and LC link status question

Hi guys,

 

Currently I am doing a fix of the link status (ISP) detect on the GTM. In this case there are two ISP on LC and the wideip on GTM are point different IP for the pool member. LC is using performance layer 4 VS to point the LTM VS server.

 

However we found the if there is one ISP Link on the LC is down, the wide ip pool member does not detect and still keep in green. It caused some client coming from the down lSP link cannot access.

 

Is that any way to make the GTM correctly detect the link status on LC? Thanks a lot