Data Transmission Method, Apparatus, and System

A system, comprising:

• a mobility management network element;
• and
• a session management network element, wherein the session management network element is configured to:
• send second information to the mobility management network element, the second information triggering establishment of a communication connection between a first terminal and a first access network device, and the communication connection is associated with transmitting data of a first multicast service;
• and
• the mobility management network element is configured to:
• receive the second information, and
• send fifth information to the first access network device based on the second information, wherein the fifth information causes the first access network device to establish the communication connection to the first terminal.

An apparatus, comprising:

• one or more processors;
• and
• a non-transitory computer readable storage medium storing programming, the programming including instructions that, when executed by the one or more processors, cause the apparatus to perform operations including:
• receiving second information from a session management network element, wherein the second information is for triggering establishment of a communication connection between a first terminal and a first access network device, and wherein the communication connection is associated with transmitting data of a first multicast service;
• and
• sending fifth information to the first access network device based on the second information, wherein the fifth information causes the first access network device to establish the communication connection to the first terminal.