ADFS Geo redundancy with Office 365

Hello,

 

I do have a single server ADFS farm (using WID and no proxy), serving both internal and internet based users.

 

I do want to add a second ADFS server to this farm, in a different GEO location (SITE to SITE VPN in place)

 

I believe Win NLB does not support 2 servers with different subnet, does F5 have something over this?

 

Thanks