Communication method, access network device, and terminal device to facilitate communication in a network slice architecture

1. A communication method comprising:

forwarding, by a first access network device to a core network device, a non-access stratum (NAS) message received from a terminal device, wherein the NAS message comprises information received from a terminal device about a correspondence between a packet data unit (PDU) session of the terminal device and a network slice;

receiving, by the first access network device from the core network device, an NG application protocol (NGAP) message that comprises the information and a maximum quantity of accessible network slices of the terminal device;

storing, by the first access network device, the information; and

sending, by the first access network device, the information to a second access network device.

2. The communication method according to claim 1 , further comprising:

sending, by the first access network device and to the terminal device, one or more instructions that instruct the terminal device to send the correspondence to the first access network device; and

receiving, by the first access network device and from the terminal device, the NAS message in response to the one or more instructions.

3. The communication method according to claim 2 , wherein the one or more instructions further includes a preset condition and the terminal device is instructed to send the NAS message in response to the preset condition being satisfied.

4. A communication method comprising:

obtaining, by a terminal device, information about a correspondence between a packet data unit (PDU) session of the terminal device and a network slice; and

sending, by the terminal device, a non-access stratum (NAS) message that comprises the information to first access network device to be forwarded to a core network device for processing and sent to a second access network device, wherein the core network device sends the information in an NG application protocol (NGAP) message after processing, for the first access network device to send to the second access network device, wherein the NGAP message comprises the information and a maximum quantity of accessible network slices of the terminal device.

5. The communication method according to claim 4 , wherein obtaining the information about the correspondence comprises:

receiving, by the terminal device and from the first access network device, one or more instructions instruct the terminal device to send the correspondence to the first access network device; and

sending, by the terminal device and to the first access network device, the information about the correspondence.

6. An access network device, comprising:

a communications interface;

at least one processor coupled to the communications interface; and

a memory coupled to the at least one processor and storing programming instructions for execution by the at least one processor, the programming instructions instruct the at least one processor to:

forward, by using the communications interface, a non-access stratum (NAS) message received from a terminal device, wherein the NAS message comprises information received from a terminal device about a correspondence between a packet data unit (PDU) session of the terminal device and a network slice;

receive, by using the communications interface from a core network device, an NG application protocol (NGAP) message that comprises the information and a maximum quantity of accessible network slices of the terminal device;

store the information; and

send, by using the communications interface, the information to a second access network device.

7. The access network device according to claim 6 , the programming instructions further instruct the at least one processor to:

send, by using the communications interface, one or more instructions to the terminal device, wherein the one or more instructions instruct the terminal device to send the correspondence to the access network device; and

receive, by using the communications interface, the NAS message in response to the one or more instructions.

8. The access network device according to claim 7 , wherein the one or more instructions further includes a preset condition and the terminal device is instructed to send the NAS message in response to the preset condition being satisfied.

9. The access network device according to claim 6 , wherein the network slice comprises a first network slice and a second network slice, the correspondence is a first correspondence between the PDU session and the first network slice, and

the information further comprises a second correspondence between the PDU session and the second network slice.

10. A terminal device, wherein the terminal device comprises:

a communications interface;

at least one processor coupled to the communications interface; and

a memory coupled to the at least one processor and storing programming instructions for execution by the at least one processor, the programming instructions instruct the at least one processor to:

obtain information about a correspondence between a packet data unit (PDU) session of the terminal device and a network slice; and

send, through the communications interface, a non-access stratum (NAS) message that comprises the information about the correspondence to first access network device to be forwarded to a core network device for processing and sent to a second access network device, wherein the core network device sends the information in an NG application protocol (NGAP) message after processing, for the first access network device to send to the second access network device, wherein the NGAP message comprises the information and a maximum quantity of accessible network slices of the terminal device.

11. The terminal device according to claim 10 , wherein obtain the information about the correspondence comprises:

receiving one or more instructions sent by the first access network device, wherein the one or more instructions instruct the terminal device to send the correspondence to the first access network device; and

sending the information about the correspondence to the first access network device.