Terminal interaction with different user plane function entities

A data transmission method comprising:

• receiving, by a first user plane function entity, a data packet from a first terminal through an uplink path corresponding to the first terminal, wherein the data packet comprises first addressing information of a second terminal, wherein the first addressing information comprises an internet protocol (IP) or a media access control (MAC) address of the second terminal, and wherein the first user plane function entity currently serves the first terminal;
• determining, by the first user plane function entity based on uplink information about the uplink path, and identity of a same mobile local area network (MLAN) in which the first terminal and the second terminal are located, wherein the uplink information about the uplink path corresponding to the first terminal comprises a first tunnel identifier of the first user plane function entity, and wherein the first tunnel identifier is allocated for the first terminal;
• determining, by the first user plane function entity based on the identity of the same MLAN and the first addressing information, first path information of a second user plane function entity, wherein the second user plane function entity currently serves the second terminal, wherein the first path information comprises a second tunnel identifier of the second user plane function entity, and wherein the second tunnel identifier is allocated for a second tunnel between the first user plane function entity and the second user plane function entity;
• sending, by the first user plane function entity, the data packet to the second user plane function entity based on the first path information;
• receiving, by the second user plane function entity, the data packet from the first user plane function entity;
• and
• sending, by the second user plane function entity, the data packet to the second terminal through a downlink path corresponding to the second terminal.