A method performed by a network node of a communications network for enabling internet protocol, IP, based deterministic networking. The method comprises receiving a routing request from a software-defined networking (SDN) controller, particularly wherein the SDN controller is associated with a deterministic network (DetNet); determining whether the routing request conflicts with the routing of the communications network; and responsive to determining whether the routing request conflicts with the routing of the communications network, transmitting a response to the SDN controller indicating acceptance or denial of the routing request. The network node may be a Deterministic Networking Application Function (DetNet AF).