[en] The Routing Research Group (RRG) of the Internet Research Task Force (IRTF) is currently discussing several architectural solutions to build an interdomain routing architecture that scales better than the existing one. The solutions family currently being discussed concerns the addresses separation into locators and identifiers, LISP being one of them. Such a separation provides opportunities in terms of traffic engineering. In this paper, we propose an open and flexible solution that allows an ISP using identifier/locator separation to engineer its interdomain traffic. Our solution relies on the utilization of a service that transparently ranks paths using cost functions. We implement a prototype server and demonstrate its benefits in a LISP testbed.