Network virtualization and cloudification are being actively introduced into mobile networks, but the current control-plane (CP) architecture, which distinguishes radio access network (RAN) from core network (CN), is inefficient in fully utilizing the flexibility provided by such technologies. In this paper, we propose a novel CP architecture, which is based on service-based interface (SBI) throughout the network without distinction between RAN and CN, thus reducing the delay and overhead of control signaling. The proposed architecture not only reduces the completion time and amount of signaling of the control procedures by up to 27% and 45%, respectively, but also provides a cloud-friendly environment in which slices and sub-networks with various characteristics can be easily operated by configuring the CP at will.