ISP monitoring on VIP's

Hello,

 

I asked this question before but newer gor a clear answer. I have the following issue: Our firm has two different ISP's (BGP not possible). Currently, we are using the DNS Made Easy function of failover-ing our outside DNS's between IP's on both ISP's when one link is down - but it is very unreliable and a lot of times it wrongly recognises a »downlink«.

 

The F5 in our system has all the modules and we have it setup as shows the picture.

 

 

So for instance, we have: VIP ISP1: 1.1.1.20 VIP ISP2: 2.2.2.20 (both are directly outside IP's routed to the F5).

 

DNS/GTM is set that points to 1.1.1.20 and 2.2.2.20.

 

How can I monitor the outside reachablility? Somebody suggested link monitoring but I'm not sure this would be the case. Another option is to monitor ISP's gateways, but I'm not sure how to accomplish that.

 

Does anybody have any suggestion?

 

TY, Daniel