One disclosure of the present specification provides a method by which a user equipment (UE) performs a protocol data unit (PDU) session establishment procedure for a local area data network (LADN). The method comprises: when a pre-set condition related to an LADN policy is satisfied, transmitting a message requesting an access and mobility management function (AMF) for the LADN policy; receiving, from the AMF, the LADN policy provided by a policy control function (PCF), wherein the LADN policy comprises information about at least one application and information about a LADN data network name (DNN) related to the at least one application; determining a LADN DNN to be used by the UE, on the basis of the LADN policy; and transmitting a PDU session establishment request message related to the determined LADN DNN to the AMF.