A first base station (1) is configured to send, to a second base station (2), first configuration information that is necessary to establish a data bearer and a data radio bearer in the second base station (2) for a C/U-plane split scenario (S105). Further, the first base station (1) is configured to keep the first configuration information in the first base station (1) even after the data bearer and the data radio bearer are established in the second base station (2) (S109). It is thus, for example, possible to contribute to a reduction in a path switch delay when a UE moves between cells in the C/U-plane split scenario.