Communication method, device, and system

A communication method implemented by a first core network device or a chip in the first core network device, the communication method comprising:

• receiving, from a target access network device, a first message that comprises a first identifier identifying a first multicast service and comprises first information about the target access network device, wherein the first message is for the target access network device to request to establish a first multicast session corresponding to the first multicast service;
• and
• sending, to the target access network device, second information of the first multicast service,
• wherein the second information comprises first path information and a second identifier of the first multicast session,
• wherein the first path information comprises a multicast address and a first tunnel identifier,
• wherein the multicast address is for the target access network device to receive data in a multicast mode, and
• wherein the first tunnel identifier identifies a multicast tunnel through which the target access network device receives the data in the multicast mode.

A target access network device comprising:

• a non-transitory memory configured to store computer-executable instructions;
• and
• one or more processors coupled to the non-transitory memory and configured to execute the computer-executable instructions to cause the target access network device to:
• receive, from a source access network device, a first identifier identifying a first multicast service;
• determine a transmission mode for transmitting data of the first multicast service between the target access network device and a first terminal device based on a quantity of terminal devices that receive the data through the target access network device, wherein the transmission mode comprises a unicast mode or a multicast mode;
• receive, from the source access network device, quality of service (QoS) information about a QoS flow of the first multicast service;
• determine wireless configuration information corresponding to the transmission mode based on the QoS information;
• send the wireless configuration information to the first terminal device through the source access network device;
• and
• send a first message to a first core network device, wherein the first message comprises the first identifier, and wherein the first message requests to establish a first multicast session corresponding to the first multicast service.

A core network device comprising:

• a non-transitory memory configured to store computer-executable instructions;
• and
• one or more processors coupled to the non-transitory memory and configured to execute the computer-executable instructions to cause the core network device to:
• receive, from a target access network device, a first message that comprises a first identifier for identifying a first multicast service and comprises first information about the target access network device, wherein the first message is for the target access network device to request to establish a first multicast session corresponding to the first multicast service;
• and
• send, to the target access network device, second information of the first multicast service,
• wherein the second information comprises first path information and a second identifier of the first multicast session,
• wherein the first path information comprises a multicast address and a first tunnel identifier,
• wherein the multicast address is for the target access network device to receive data in a multicast mode, and
• wherein the first tunnel identifier identifies a multicast tunnel through which the target access network device receives the data in the multicast mode.