S130. The first network node receives a second message sent by the first system based on the first message, where the second message includes identification information of the terminal device, and the identification information of the terminal device is used by the first network node to retrieve context information of the terminal device that is stored at the first network node, or the second message includes context information of the terminal device, and the context information of the terminal device is access stratum context information.
Optionally, the context information of the terminal device includes at least one of a radio resource control configuration, a data radio bearer parameter, the identification information of the terminal device, cell identifier information, and connection information of a first interface. The first interface is used for data transmission and information exchange between the first network node and the first system.
S140. The first network node retrieves, based on the identification information of the terminal device that is carried in the second message, the context information of the terminal device that is stored at the first network node, or re-establishes the context information of the terminal device.
Optionally, the first message is an RRC connection resume request message or an RRC connection re-establishment request message.
Optionally, the first network node includes at least one of a Radio Link Control protocol layer function, a Media Access Control layer function, and a physical layer function; and/or the first system includes at least one of a Packet Data Convergence Protocol layer function, a Service Data Adaptation Protocol layer function, and a Radio Resource Control function.