F5 bigip link controller

Hello, I'm very green when it comes to F5 and link controllers. The company I work for uses a bigip link controller to split traffic between 2 ISP. Yesterday one of the ISP went down but the LC didn't detect it and was still balancing traffic to it. I took a look at the config and only saw 1 monitor called bigip_link. Looks like it's the default monitor? I have worked with other brand of link controller before and shouldn't the LC monitor external address (like google) to be able to trigger an ISP outage?

 

 

Maybe it is a stupid question but the behavior of the link controller was not what I expected in case of a ISP failure.