The present disclosure is directed to a method in a radio access node 14 and to a radio access node 14 for performing the method in a cellular communications network 10. The method comprises: sending 102 to a mobility function entity 18 in a core network of the cellular communications network 10, first information indicative of one or more tracking areas supported by the radio access node 14 and one or more network slices supported by the radio access node 14; and receiving 112B from the mobility function entity 18, second information indicative of one or more network slices that are: (a) supported by the radio access node 14 and the mobility function entity 14 and (b) permitted by one or more network policies, for each of at least one of the one or more tracking areas supported by the radio access node 14; or (a) supported by the mobility function entity 14 and (b) permitted by one or more network policies, for each of at least one of the one or more tracking areas supported by the radio access node 14. The disclosure is also directed to a corresponding method in a mobility function entity and a corresponding configured mobility function entity.