Method, device, and system for network switching involving network slice selection
A mobility management network element in a visited network performs a method in a home-routed roaming operation to facilitate a switching of a terminal in a session to the visited network. The mobility management network element obtains single network slice selection assistance information (S-NSSAI) for a home network of the terminal corresponding to the session of the terminal. The mobility management network element also obtains S-NSSAI for the visited network corresponding to the session of the terminal, according to a mapping relationship between the S-NSSAI for the home network and the S-NSSAI for the visited network. The mobility management network element then sends the S-NSSAI for the visited network to an access device of the terminal in the visited network, for the access device to process the session.
1. A method performed by an access and mobility management function network element in a visited network in a home-routed roaming operation in which a terminal accesses the visited network, comprising:
obtaining single network slice selection assistance information (S-NSSAI) for a home network corresponding to a session of the terminal, wherein the access and mobility management function network element receives the S-NSSAI for the home network from a visited session management network element in the visited network;
obtaining S-NSSAI for the visited network corresponding to the session of the terminal, based on a mapping relationship between the S-NSSAI for the home network and the S-NSSAI for the visited network; and
sending, the S-NSSAI for the visited network to an access device of the terminal in the visited network.
2. The method according to claim 1 , wherein the step of obtaining the S-NSSAI for the visited network comprises:
obtaining the S-NSSAI for the visited network based on the S-NSSAI for the home network and indication information of the home network.
3. The method according to claim 2 , wherein the step of obtaining the S-NSSAI for the visited network comprises:
sending a message to a slice selection function network element, wherein the message comprises the S-NSSAI for the home network and the indication information of the home network; and
receiving, from the slice selection function network element, the S-NSSAI for the visited network.
4. The method according to claim 1 , further comprising:
before sending the S-NSSAI for the visited network to the access network, sending a default S-NSSAI for the visited network to the access network.
5. The method according to claim 4 , wherein the step of sending the default S-NSSAI comprises:
sending the default S-NSSAI for the visited network to the access network though the visited session management network element in the visited network.
6. The method according to claim 1 , wherein the step of sending the S-NSSAI for the visited network comprises:
sending the S-NSSAI for the visited network to the access device though the visited session management network element in the visited network.
7. An apparatus, comprising:
a processor; and
a memory storing executable instructions;
wherein the processor is configured to execute the executable instructions to perform operations of:
in a home-routed roaming operation in which a terminal accesses a visited network that comprises the apparatus, obtaining single network slice selection assistance information (S-NSSAI) for a home network corresponding to a session of the terminal, wherein the apparatus receives the S-NSSAI for the home network from a visited session management network element in the visited network;
obtaining S-NSSAI for the visited network corresponding to the session of the terminal, based on a mapping relationship between the S-NSSAI for the home network and the S-NSSAI for the visited network; and
sending the S-NSSAI for the visited network to an access device of the terminal in the visited network.
8. The apparatus according to claim 7 , wherein the operation of obtaining the S-NSSAI for the visited network comprises:
obtaining the S-NSSAI for the visited network based on the S-NSSAI for the home network and indication information of the home network.
9. The apparatus according to claim 8 , wherein the operation of obtaining the S-NSSAI for the visited network comprises:
sending a message to a slice selection function network element, wherein the message comprises the S-NSSAI for the home network and the indication information of the home network; and
receiving the S-NSSAI for the visited network from the slice selection function network element.
10. The apparatus according to claim 7 , wherein before sending the S-NSSAI for the visited network, the processor is further configured to perform an operation of:
sending a default S-NSSAI for the visited network to the access network.
11. The apparatus according to claim 10 , wherein the operation of sending the default S-NSSAI comprises:
sending the default S-NSSAI for the visited network to the access network though the visited session management network element in the visited network.
12. The apparatus according to claim 7 , wherein the operation of sending the S-NSSAI for the visited network comprises:
sending the S-NSSAI for the visited network to the access device though the visited session management network element in the visited network.
13. A system for carrying out a home-routed roaming operation, comprising:
an access and mobility management function network element in a visited network accessed by a terminal in the home-routed roaming operation; and
an access device in the visited network for handling access of the terminal to the visited network;
wherein the access and mobility management function network element is configured to:
obtain single network slice selection assistance information (S-NSSAI) for a home network corresponding to a session of the terminal, wherein the access and mobility management function network element receives the S-NSSAI for the home network from a visited session management network element in the visited network;
obtain S-NSSAI for the visited network corresponding to the session of the terminal, based on a mapping relationship between the S-NSSAI for the home network and the 5-NSSAI for the visited network; and
send the S-NSSAI for the visited network to the access device in the visited network;
wherein the access device is configured to:
receive the S-NSSAI for the visited network from the access and mobility management function network element; and
process the session of the terminal according to a policy for a network slice corresponding to the S-NSSAI for the visited network.
14. The system according to claim 13 ,
wherein the access and mobility management function network element is further configured to send a default S-NSSAI for the visited network to the access network; and
wherein the access network is further configured to receive the default S-NSSAI for the visited network from the access and mobility management function network element.