Data buffering method and session management function entity

A data buffering method comprising:

• interacting, by a session management function network element, with a second user plane function network element and a first user plane function network element, wherein the first user plane function network element is an anchor user plane function network element of a first session, wherein the second user plane function network element is connected to an access network device, and wherein a transmission path of first downlink data of the first session passes through the first user plane function network element, the second user plane function network element, and the access network device;
• determining, by the session management function network element, whether to release the second user plane function network element after the terminal device switches to an idle state;
• releasing, by the session management function network element, the second user plane function network element when the session management function network element determines to release the second user plane function network element;
• sending, by the session management function network element, a buffering indication to the first user plane function network element, wherein the buffering indication instructs the first user plane function network element to buffer downlink data of the first session;
• and
• adding, by the session management function network element after the terminal device switches to a connected state, a third user plane function network element into the data path of the first session by interacting with the first user plane function network element and the third user plane function network element, wherein the third user plane function network element is connected to the access network device, and wherein buffered second downlink data and incoming third downlink data on the first user plane function network element are transmitted to the access network device via the third user plane function network element.

A session management function entity, comprising:

• an interface;
• a processor coupled to the interface;
• and
• a non-transitory computer-readable storage medium coupled to the processor and configured to store instructions to be executed by the processor to cause the session management function entity to:
• interact, via the interface, with a second user plane function network element and a first user plane function network element, wherein the first user plane function network element is an anchor user plane function network element of a first session, wherein the second user plane function network element is connected to an access network device, and wherein a transmission path of first downlink data of the first session passes through the first user plane function network element, the second user plane function network element, and the access network device;
• determine whether to release the second user plane function network element after the terminal device switches to an idle state;
• release the second user plane function network element when the session management function entity determines to release the second user plane function network element;
• send a buffering indication to the first user plane function network element, wherein the buffering indication instructs the first user plane function network element to buffer downlink data of the first session, and
• add after the terminal device switches to a connected state, a third user plane function network element into the data path of the first session by interacting with the first user plane function network element and the third user plane function network element, wherein the third user plane function network element is connected to the access network device, and wherein buffered second downlink data and incoming third downlink data on the first user plane function network element are transmitted to the access network device via the third user plane function network element.

A data buffering method, comprising:

• interacting, by a session management function network element, with a second user plane function network element and a first user plane function network element, wherein the first user plane function network element is an anchor user plane function network element of a first session, wherein the second user plane function network element is connected to an access network device, and wherein a transmission path of first downlink data of the first session successively passes through the first user plane function network element, the second user plane function network element, and the access network device;
• determining whether to release the second user plane function network element after the terminal device switches to an idle state;
• releasing, by the session management function network element, the second user plane function network element when the session management function network element determines to the second user plane function network element;
• sending, by the session management function network element, a buffering indication to the first user plane function network element, wherein the buffering indication instructs the first user plane function network element to buffer downlink data of the first session;
• receiving, by the first user plane function network element, the buffering indication;
• buffering, by the first user plane function network element, second downlink data of the first session in response to the buffering indication;
• adding, by the session management function network element after the terminal device switches to a connected state, a third user plane function network element into the data path of the first session by interacting with the first user plane function network element and the third user plane function network element, wherein the third user plane function network element is connected to the access network device;
• and
• sending, by the first user plane function network element, the second downlink data and incoming third downlink data to the access network device via the third user plane function network element.