How to set Big IP to full proxy for a VS

Hi,

I recently setup a Big IP 2000 (v11.2.1) in my lab. I am now discovering that my app does not like direct server return. I need the Real Servers to respond back to the Big IP VIP and not directly to the Client.

This seems like it should be a simple setting on the Big IP to change this but for the life of me I cannot seem to find it. And searching hasn't seemed to help either. What setting is this that allows the Big IP to replace the Src address in requests with the VIP address instead? Is it just a simple switch that you enable on the VS like Netscalers allow or do I need some SNAT/iRules/other cfg to make this change?

Thank you.