A middlebox system that maintains a load balancing configuration in a large scale IoT deployment is provided. The system performs reverse address translation for a first packet of a particular application from a first server to a first client according to a binding structure that couples a source address indicating the first client with (i) a destination addresses indicating the first server and (ii) an application client marker of the first client for the particular application. The system performs reverse address translation for a second packet of the particular application from a second server to the first client by using the application client marker in the binding structure to determine the source address indicating the first client.