How is the best way to balance web apps between 2 data centers each with their own internet?

Isn't failsafe just for an HA pair? I am taking about 2 HA pairs at different data centers each with different internet.

Well, that changes things :) ----------------------- I think you should talk through it. In short: you have to put something in front of the pairs, if you want to load balance between them. ------------------------- If traffic goes to one pair, and it's down, then that traffic is going to be lost. If you expect traffic will go to one pair and that pair will be working, but a VLAN it provides access to is down, then you could set up some sort of redirect. On the BIG-IP everything comes down to LISTENERS. So you'd have to find the LISTENER that gets the traffic (likely a vip, but could be a snat or a nat) and apply the redirect there (in this case snat or nat could be used). And what type of redirect are we talking about? A HTTP redirect is only layer 7. Your lower level options are...less exciting. ICMP message? Reject the packet? All possible, but your solution will depend on how your network and clients handle such things --------------------- Again, everything points to having a device in front of them, monitoring them, and intelligently selecting which one to send the traffic to, is the best solution.