A communication method, characterized by comprising: receiving, by a relay device, a first data packet from a first terminal through a first transmission link, wherein the first data packet comprises an identifier of a second terminal and data to be sent to the second terminal, the first transmission link is a transmission link between the relay device and the first terminal, the first transmission link is used for the first terminal communicating with at least two communication devices, and the at least two communication devices comprise the second terminal; and sending, by the relay device, a second data packet to the second terminal through a second transmission link based on the identifier of the second terminal, wherein the second data packet comprises the data to be sent to the second terminal, and the second transmission link is a transmission link between the relay device and the second terminal, characterized in that the sending, by the relay device, a second data packet to the second terminal through a second transmission link based on the identifier of the second terminal comprises: obtaining, by the relay device, identification information of the second transmission link based on the identifier of the second terminal and a correspondence; and sending, by the relay device, the second data packet to the second terminal through the second transmission link based on the identification information of the second transmission link, wherein the correspondence comprises: a correspondence between the identifier of the second terminal and the identification information of the second transmission link; or a correspondence between the identifier of the second terminal, a layer 2 identifier of the relay device, and the identification information of the second transmission link. receiving, by a relay device, a first data packet from a first terminal through a first transmission link, wherein the first data packet comprises an identifier of a second terminal and data to be sent to the second terminal, the first transmission link is a transmission link between the relay device and the first terminal, the first transmission link is used for the first terminal communicating with at least two communication devices, and the at least two communication devices comprise the second terminal; and sending, by the relay device, a second data packet to the second terminal through a second transmission link based on the identifier of the second terminal, wherein the second data packet comprises the data to be sent to the second terminal, and the second transmission link is a transmission link between the relay device and the second terminal, characterized in that the sending, by the relay device, a second data packet to the second terminal through a second transmission link based on the identifier of the second terminal comprises: obtaining, by the relay device, identification information of the second transmission link based on the identifier of the second terminal and a correspondence; and sending, by the relay device, the second data packet to the second terminal through the second transmission link based on the identification information of the second transmission link, wherein the correspondence comprises: a correspondence between the identifier of the second terminal and the identification information of the second transmission link; or a correspondence between the identifier of the second terminal, a layer 2 identifier of the relay device, and the identification information of the second transmission link. obtaining, by the relay device, identification information of the second transmission link based on the identifier of the second terminal and a correspondence; and sending, by the relay device, the second data packet to the second terminal through the second transmission link based on the identification information of the second transmission link, wherein the correspondence comprises: a correspondence between the identifier of the second terminal and the identification information of the second transmission link; or a correspondence between the identifier of the second terminal, a layer 2 identifier of the relay device, and the identification information of the second transmission link. a correspondence between the identifier of the second terminal and the identification information of the second transmission link; or a correspondence between the identifier of the second terminal, a layer 2 identifier of the relay device, and the identification information of the second transmission link.