Hi Aaron,
Here's what I have: an iRule which redirects traffic to either default or login pool based on the uri. If no members are available in the selected pool, an error page is displayed (not good since second DC might still be available).
Here's what I want to have: somehow detect (maybe it should be done on GTM layer) that both pools are down, and send traffic to another Data Center. I thought of having one pool per VIP, and have a VIP as a pool member. This way, if no members are active, the VIP should be marked down before it's requested, and LTM or GTM would route traffic to another VIP in second DC. If second DC has the same condition (nothing available), then an error page should be displayed.
I hope that makes sense.
Thank you,
Roman