TO create https failover between DC and DR

[ivar436]

We are executing a project of setting up a DR site with storage replication. We are planning to execute application failover between DC and DR. in phase  iwe have installed 2 web servers(residing in DMZ zone and natted to global ip in DC) for DR.Also we are trying to failover an internal application also.It s in VMWARE .After discussion we saw a possibility to configure a failover using PF Sense but how to do it!!!.. Our current DC setup has switch–>Router-->Checkpoint utm (DMZ configured here)-->Core Switch(vlans here)-->Server Switch-->Internal Servers. THe Dr site shall have p-2-p link with DC and have ROuter-->ASA-->L2 switch-->servers.

Our routing is done in router and all vlans are in core switch and natting done in UTM. THe diagram is attached. i need help in figuring out how to configure this.Need to setup such that if the PFsense senses DC internal network down, it switches to DR and web services (globally)and internal application can be accessed from it.