Implementations of this application provide communications methods, devices, and chips. In an implementation, a method comprises: sending, by a centralized unit user plane (CU-UP) of an access network to a centralized unit control plane (CU-CP) of the access network, an interface setup request message to request to setup an E1 interface, the interface setup request message comprises an identity of a public land mobile network (PLMN) served by the CU-UP and a network slice identifier corresponding to the public land mobile network, wherein the network slice identifier identifies single network slice selection assistance information (S-NSSAI) or an S-NSSAI list; and sending, by the CU-CP, an interface setup response message to the CU-UP after receiving the interface setup request message.