Methods and apparatuses for instantiation of network service (NS) or virtualized network function (VNF) are disclosed. A virtualized network function manager (VNFM) receives, from a first network management entity, a first request for instantiating or changing a VNF instance. The first request comprises scaling information for at least one scalable VNF deployment unit (VDU) included in the VNF instance. The VNFM instantiates or changes the VNF instance based on the scaling information.