A method for controlling a user-plane bearer to be established, comprising: determining , by a Mobility Management Entity, MME, whether a Serving Gateway, SGW needs to transmit buffered downlink data to a User Equipment, UE, in a Tracking Area Update, TAU procedure; if so, initiating , by the MME, a procedure of establishing a user-plane bearer for the UE; otherwise, not initiating, by the MME, a procedure of establishing a user-plane bearer for the UE; wherein determining , by the MME, that the Serving Gateway, SGW needs to transmit buffered downlink data to the User Equipment, UE comprises: determining, by the MME, a time of receiving a Context Request message of a new MME which is relocated, is earlier than a recorded timestamp, the recorded timestamp is determined by the MME from a length of time for which the MME indicates the SGW to buffer downlink data of the UE in a case of determining that the UE is unreachable; or the recorded timestamp is a sum of a time when the MME indicates the SGW to buffer downlink data of the UE in a case of determining that the UE is unreachable, and a length of time for which the MME indicates the SGW to buffer downlink data of the UE; or determining, by the MME, that a time when a bearer related message of the SGW is received is earlier than a recorded timestamp, which is determined by the MME from a length of time for which the MME indicates the SGW to buffer downlink data of the UE in a case of determining that the UE is unreachable; or which is a sum of a time when the MME indicates the SGW to buffer downlink data of the UE in a case of determining that the UE is unreachable, and a length of time for which the MME indicates the SGW to buffer downlink data of the UE. determining , by a Mobility Management Entity, MME, whether a Serving Gateway, SGW needs to transmit buffered downlink data to a User Equipment, UE, in a Tracking Area Update, TAU procedure; if so, initiating , by the MME, a procedure of establishing a user-plane bearer for the UE; otherwise, not initiating, by the MME, a procedure of establishing a user-plane bearer for the UE; determining, by the MME, a time of receiving a Context Request message of a new MME which is relocated, is earlier than a recorded timestamp, the recorded timestamp is determined by the MME from a length of time for which the MME indicates the SGW to buffer downlink data of the UE in a case of determining that the UE is unreachable; or the recorded timestamp is a sum of a time when the MME indicates the SGW to buffer downlink data of the UE in a case of determining that the UE is unreachable, and a length of time for which the MME indicates the SGW to buffer downlink data of the UE; or determining, by the MME, that a time when a bearer related message of the SGW is received is earlier than a recorded timestamp, which is determined by the MME from a length of time for which the MME indicates the SGW to buffer downlink data of the UE in a case of determining that the UE is unreachable; or which is a sum of a time when the MME indicates the SGW to buffer downlink data of the UE in a case of determining that the UE is unreachable, and a length of time for which the MME indicates the SGW to buffer downlink data of the UE. <EOS>