Network handover method and apparatus

1. A network handover method, comprising:

before a terminal device is handed over from a first network to a second network, setting up, by the terminal device, a first tunnel to a first interworking device, wherein a communication identifier, of the terminal device, in the first tunnel is a first identifier, the first identifier is an identifier used in the first network by the terminal device, and the first interworking device is an interface device that is in the first network and connected to a network other than the first network; and

after the terminal device is handed over from the first network to the second network, obtaining, by the terminal device, a second identifier that is an identifier used in the second network by the terminal device and;

sending an update request to the first interworking device, wherein the update request includes a request to update the communication identifier to the second identifier.

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

before the terminal device is handed over from the first network to the second network, sending, by the terminal device, a first message to an access management device of the second network through a second interworking device, wherein the first message includes a request to register the terminal device with the second network, and the second interworking device is an interface device that is in the second network and oriented toward a network other than the second network;

receiving, by the terminal device, a response message from the access management device of the second network through the second interworking device, wherein the response message comprises a temporary identifier allocated by the access management device of the second network to the terminal device; and

in response to the terminal device being handed over from the first network to the second network, sending, by the terminal device, a second message to the access management device of the second network, wherein the second message includes a request to register the terminal device with the second network, and the second message comprises the temporary identifier.

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

before the terminal device is handed over from the first network to the second network, sending, by the terminal device, a registration request to an access management device of the first network through the first interworking device.

4. The method according to claim 3 , wherein the registration request comprises pre-handover indication information, and the pre-handover indication information indicates that the terminal device needs to be handed over to the second network.

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

before the terminal device is handed over from the first network to the second network, sending, by the terminal device, a channel setup request, wherein the channel setup request includes a request to set up a first channel between the first interworking device and a forwarding device of the first network, and the first channel belongs to a session of the terminal device.

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

sending, by the terminal device, a first cache indication to the first interworking device, wherein the first cache indication indicates that the first interworking device cache received first downlink data of the first channel.

7. A network handover apparatus, comprising:

a memory storage comprising instructions; and

one or more processors in communication with the memory, wherein the one or more processors execute the instructions to:

before a terminal device is handed over from a first network to a second network, set up a first tunnel to a first interworking device, wherein a communication identifier, of the terminal device, in the first tunnel is a first identifier, the first identifier is an identifier used in the first network by the terminal device, and the first interworking device is an interface device that is in the first network and oriented toward a network other than the first network; and

after the terminal device is handed over from the first network to the second network, obtain a second identifier that is an identifier used in the second network by the terminal device and;

send an update request to the first interworking device, wherein the update request includes a request to update the communication identifier to the second identifier.

8. The apparatus according to claim 7 , wherein the one or more processors further execute the instructions to: before the terminal device is handed over from the first network to the second network, send a first message to an access management device of the second network through a second interworking device, wherein the first message is a request to register the terminal device with the second network, and the second interworking device is an interface device that is in the second network and oriented toward a network other than the second network; configured to receive a response message from the access management device of the second network through the second interworking device, wherein the response message comprises a temporary identifier allocated by the access management device of the second network to the terminal device; and configured to: in response to the terminal device being handed over from the first network to the second network, send a second message to the access management device of the second network, wherein the second message includes a request to register the terminal device with the second network, and the second message comprises the temporary identifier.

9. The apparatus according to claim 7 , wherein the one or more processors further execute the instructions to: send a registration request to the access management device of the first network through the first interworking device before the terminal device is handed over from the first network to the second network.

10. The apparatus according to claim 7 , wherein the one or more processors further execute the instructions to: indicate, before the terminal device is handed over from the first network to the second network, the first interworking device to set up a first channel to a forwarding device of the first network, wherein the first channel belongs to a session of the terminal device.

11. The apparatus according to claim 10 , wherein the one or more processors further execute the instructions to: unit send a first cache indication to the first interworking device, wherein the first cache indication indicates that the first interworking device cache received first downlink data of the first channel.

12. The apparatus according to claim 10 , wherein the one or more processors further execute the instructions to: send trigger information to the forwarding device of the first network, wherein the trigger information indicates that the forwarding device of the first network send downlink data of the terminal device through the first channel.

13. The apparatus according to claim 10 , wherein the one or more processors further execute the instructions to: send a reservation indication, wherein the reservation indication includes a request to reserve a second channel, the second channel is a channel between an access device of the first network and the forwarding device of the first network, and the first channel and the second channel belong to a same session.

14. The apparatus according to claim 7 , wherein the one or more processors further execute the instructions to: before the terminal device is handed over from the first network to the second network, send a forwarding tunnel setup request, wherein the forwarding tunnel setup request includes a request to set up, between an access device of the first network and the first interworking device, a forwarding tunnel for transmitting the downlink data of the terminal device.

15. The apparatus according to claim 14 , wherein the one or more processors further execute the instructions to: send a second cache indication to the first interworking device, wherein the second cache indication indicates that the first interworking device cache second downlink data received through the forwarding tunnel.

16. A network handover apparatus, comprising:

a memory storage comprising instructions; and

one or more processors in communication with the memory, wherein the one or more processors execute the instructions to:

set up a first tunnel from a first interworking device to a terminal device in a first network, wherein a communication identifier, of the terminal device, in the first tunnel is a first identifier, the first identifier is an identifier used in the first network by the terminal device, and the apparatus is an interface device that is in the first network and oriented toward a network other than the first network; and

receive an update request sent by the terminal device, wherein the update request includes a request to update the communication identifier to a second identifier that is an identifier used in a second network by the terminal device, wherein

update the communication identifier, of the terminal device, in the first tunnel to the second identifier based on the update request.

17. The apparatus according to claim 16 , wherein the one or more processors further execute the instructions to: set up a first channel to a forwarding device of the first network, wherein the first channel belongs to a session of the terminal device;

cache first downlink data received through the first channel; and

send the first downlink data to the terminal device through the first tunnel after the communication identifier, of the terminal device, in the first tunnel is updated to the second identifier.

18. The apparatus according to claim 17 , wherein the one or more processors further execute the instructions to: unit receive a first cache indication sent by the terminal device, wherein the first cache indication indicates that the first interworking device cache the first downlink data received through the first channel; and

unit cache, unit the first downlink data based on the first cache indication.

19. The apparatus according to claim 16 , wherein the one or more processors further execute the instructions to: unit set up a forwarding tunnel to the access device of the first network, wherein the forwarding tunnel is configured to transmit second downlink data of the terminal device;

unit cache the second downlink data received through the forwarding tunnel; and

unit send the second downlink data to the terminal device through the first tunnel after the communication identifier, of the terminal device, in the first tunnel is updated to the second identifier.

20. The apparatus according to claim 19 , wherein the one or more processors further execute the instructions to:

unit receive a second cache indication, wherein the second cache indication indicates that the first interworking device cache the second downlink data received through the forwarding tunnel; and

unit cache the second downlink data based on the second cache indication.