Communication method and apparatus, and device

1. A communication method, comprising:

receiving, by a base station, a first message from a session management function network element, wherein the first message is used for adding a terminal device to a multicast session corresponding to a multicast service, the first message comprises first indication information, and the first indication information indicates the multicast session;

sending, by the base station, a first request message to a second network device, wherein the first request message requests to establish the multicast session corresponding to the multicast service, and the first request message comprises an identifier of the multicast service;

receiving, by the base station, multicast information of the multicast service from the second network device;

determining, by the base station, radio bearer information based on the multicast information; and

sending, by the base station, the radio bearer information corresponding to the multicast session to the terminal device based on the first message, wherein the radio bearer information is used by the terminal device to join the multicast session.

2. The method according to claim 1 , wherein the first message is an N2 message.

3. The method according to claim 1 , wherein

the first request message is sent in response to the base station having not established the multicast session corresponding to the multicast service.

4. The method according to claim 1 , wherein the multicast information comprises: quality of service (QoS) information of a multicast QoS flow of the multicast service and an identifier of the multicast QoS flow.

5. The method according to claim 1 , wherein the method further comprises:

sending, by the base station, user plane tunnel information of the multicast session on the base station to the second network device.

6. The method according to claim 1 , wherein the second network device is a multicast control function network element.

7. A communication method, comprising:

receiving, by a session management function network element, a second message from a terminal device, wherein the second message requests a multicast service, and the second message comprises an identifier of the multicast service;

sending, by the session management function network element, first identification information to a multicast control function network element, wherein the first identification information is a multicast address of the multicast service or a multicast broadcast service identifier of the multicast service;

receiving, by the session management function network element, multicast information of the multicast service from the multicast control function network element; and

sending, by the session management function network element, a first message to a base station, wherein the first message is used for adding the terminal device to a multicast session corresponding to the multicast service, the first message comprises first indication information, the first indication information indicates the multicast session, and the base station is a base station accessed by the terminal device.

8. The method according to claim 7 , wherein the first message is an N2 message.

9. The method according to claim 7 , wherein the method further comprises:

selecting, by the session management function network element, the multicast control function network element based on the identifier of the multicast service.

10. A communication apparatus, comprising a memory and at least one processor, wherein the at least one processor executes program instructions in the memory, to implement operations comprising:

receiving a first message from a session management function network element, wherein the first message is used for adding a terminal device to a multicast session corresponding to a multicast service, the first message comprises first indication information, and the first indication information indicates the multicast session;

sending a first request message to a second network device, wherein the first request message requests to establish the multicast session corresponding to the multicast service, and the first request message comprises an identifier of the multicast service;

receiving multicast information of the multicast service from the second network device;

determining radio bearer information based on the multicast information; and

sending the radio bearer information corresponding to the multicast session to the terminal device based on the first message, wherein the radio bearer information is used by the terminal device to join the multicast session.

11. The communication apparatus according to claim 10 , wherein

the first request message is sent in response to the communication apparatus having not established the multicast session corresponding to the multicast service.

12. The communication apparatus according to claim 11 , wherein the second network device is a multicast control function network element.

13. The communication apparatus according to claim 10 , wherein the multicast information comprises: quality of service (QoS) information of a multicast QoS flow of the multicast service and an identifier of the multicast QoS flow.

14. The communication apparatus according to claim 10 , wherein the operations comprise:

sending user plane tunnel information of the multicast session on the communication apparatus to the second network device.

15. The communication apparatus according to claim 10 , wherein the first message is an N2 message.

16. A communication apparatus, comprising a memory and at least one processor, wherein the at least one processor executes program instructions in the memory, to implement operations comprising:

receiving a second message from a terminal device, wherein the second message requests a multicast service, and the second message comprises an identifier of the multicast service;

sending first identification information to a multicast control function network element, wherein the first identification information is a multicast address of the multicast service or a multicast broadcast service identifier of the multicast service;

receiving multicast information of the multicast service from the multicast control function network element; and

sending a first message to a base station, wherein the first message is used for adding the terminal device to a multicast session corresponding to the multicast service, the first message comprises first indication information, the first indication information indicates the multicast session, and the base station is a base station accessed by the terminal device.

17. The communication apparatus according to claim 16 , wherein the operations comprise:

selecting the multicast control function network element based on the identifier of the multicast service.

18. The communication apparatus according to claim 16 , wherein the first message is an N2 message.