One disclosure of the present specification provides a method by which a network control node performs communication. The method comprises the steps of: determining whether to request, from a network function (NF), control for a network slice on the basis of a session, which is managed by a network control node, being related to an interworking procedure and on the basis of the network slice being controlled by a provider policy set in the network control node, the network slice being related to the session; transmitting a control request message for the network slice to the NF, on the basis of the determination that the network control node requests control for the network slice; and receiving a response message from the NF, wherein the response message includes information about whether the session is available in the network slice.