A method includes, when a UE enters a first core network device and performs a location update, determining, by the first core network device and at least according to that a timer does not time out, that context information of the UE is available, and sending, by the first core network device, to a second core network device, a location update request that includes information that the context information of the UE is available. The method further includes executing, by the first core network device, the location update at least according to saved context information of the UE. The timer is sent to the first core network device by the second core network device before the UE enters the first core network device and when the UE leaves the first core network device and performs the location update. Alternatively, the timer is saved in the first core network device in advance.