GTM marking pool members down - can't see why

Hi,

 

I have two GTMs running 11.2.1 (latest hotfix) and I have added in a LTM running 10.2.1 (build 297) as a server.

 

The GTMs have discovered all the virtual servers on the LTM and all that looks really good, everything is all green

 

However, at regular intervals the GTM marks some of the LTM pool members down. The LTM does not mark the pools down at all.

 

Does the GTM actually poll the virtual servers on the LTM or does it just get the info via the iQuery session to the LTM?

 

I only have the bigip monitor applied to the LTM object on the GTM - it reports everything is good.

 

 

I actually can't see the GTM trying to poll the virtual servers on the LTM, so I'm thinking it must get the status of the virtual servers via from the LTM itself - in this case if the LTM isn't marking the pools down, why is the GTM?