Route optimization is based on a network enforced, and mobile implemented, policy. A communication session between a mobile device and an access router is established. First and second IP addresses to be assigned to the mobile device are received by the mobile device via the established communication session, as is a set of rules. The mobile device evaluates at least one parameter of the communication session against the set of rules to determine which of the IP addresses to use to communicate with an external device, and proceeds to communicate with the external device using the selected IP address based upon the evaluation result.