CN117042069B

CN117042069B - Path switching method and device applied to 5G core network and electronic equipment

Info

Publication number: CN117042069B
Application number: CN202311283755.2A
Authority: CN
Inventors: 刘双; 彭艺
Original assignee: New H3C Technologies Co Ltd
Current assignee: New H3C Technologies Co Ltd
Priority date: 2023-09-28
Filing date: 2023-09-28
Publication date: 2024-02-27
Anticipated expiration: 2043-09-28
Also published as: CN117042069A

Abstract

The embodiment of the application provides a path switching method and device applied to a 5G core network and electronic equipment. Based on a session update request sent by an AMF, if it is determined that a terminal managed by the SMF is not in a service range of a first UPF and the first UPF supports UPF switching, selecting a second UPF to replace the first UPF to provide services for the terminal, and further controlling the second UPF to create a forwarding tunnel with the first UPF so that the second UPF sends a downlink data message sent to the terminal to a target base station T-RAN through the tunnel instead of the first UPF; by creating the tunnel from the first UPF to the second UPF, the downlink data message can be forwarded from the first UPF to the second UPF through the tunnel in the process that the terminal moves from the first UPF service area to the second UPF service area, so that the service of the terminal is not interrupted in the process of switching the forwarding paths of the data message.

Description

Path switching method and device applied to 5G core network and electronic equipment

Technical Field

The present invention relates to the field of mobile communications technologies, and in particular, to a path switching method and apparatus applied to a 5G core network, and an electronic device.

Background

In a mobile communication system, a terminal may exceed a service area of a current UPF (User Plane Function, user plane function network element) during a mobile process, and session and service continuity need to be ensured while switching the UPF. The session and service continuity mode supported by the current 5G system can delete and reconstruct PDU (Protocol Data Unit ) session while switching UPF, which can cause current service interruption of the terminal, and it is difficult to guarantee service continuity of the terminal.

Disclosure of Invention

In view of this, the present application provides a path switching method, apparatus and electronic device applied in a 5G core network, so as to solve the problem that the related art switches UPFs and simultaneously causes service interruption, so that it is difficult to ensure service continuity.

The technical scheme provided by the application is as follows:

according to an embodiment of the first aspect of the present application, a path switching method applied in a 5G core network is provided, the method is applied to a session management function network element SMF in the 5G core network, the method includes:

based on a session update request sent by an access and mobility management function network element (AMF), determining whether a terminal managed by the SMF is in a service range of a first user plane function network element (UPF) for providing service for the terminal currently; the session update request is sent by triggering the AMF before the position of the terminal changes or after the position of the terminal changes;

If the SMF managed terminal is not in the service range of the first UPF and the first UPF is judged to support UPF switching, selecting a second UPF to replace the first UPF to provide service for the terminal; the terminal is in the service range of the second UPF;

and controlling the second UPF to create a tunnel to the first UPF so that the first UPF forwards the downlink data message of the terminal to the second UPF through the tunnel before the second UPF replaces the first UPF to send the downlink data message sent to the terminal to the target base station T-RAN.

Optionally, the terminal is in a CONNECTED CM-CONNECTED state; when the terminal is in a CM-CONNECTED state, signaling connection is established between the terminal and the AMF;

the session update request is sent by triggering the AMF before the position of the terminal changes; the session update request is used for indicating that the terminal is about to generate position change, and the session update request at least carries the position information of the base station accessed after the terminal generates position change;

the determining whether the terminal managed by the SMF is in the service range of the first user plane function network element UPF currently providing service for the terminal based on the session update request sent by the access and mobility management function network element AMF includes:

And checking whether the position information of the base station carried by the session updating request is in the service range of the first UPF which is used for providing service for the terminal currently, if so, determining that the terminal is in the service range of the first UPF which is used for providing service for the terminal currently, otherwise, determining that the terminal is not in the service range of the first UPF which is used for providing service for the terminal currently.

Optionally, the terminal is in an IDLE state CM-IDLE state; when the terminal is in a CM-IDLE state, no signaling connection is established between the terminal and the AMF;

the session update request is sent by triggering the AMF after the position of the terminal is changed; the session update request is used for indicating that the terminal has changed in position, and the session update request carries the position information of the terminal after the position change;

the determining whether the terminal managed by the SMF is in the service range of the first UPF currently providing service for the terminal based on the session update request sent by the access and mobility management function network element AMF includes:

and checking whether the position information carried by the session updating request after the position change of the terminal is in the service range of the first UPF for providing service for the terminal currently, if so, determining that the terminal is in the service range of the first UPF for providing service for the terminal currently, otherwise, determining that the terminal is not in the service range of the first UPF for providing service for the terminal currently.

Optionally, the controlling the second UPF to create the tunnel to the first UPF includes:

controlling the second UPF to create a PFCP session with the SMF, and prohibiting the second UPF from issuing the routing information of the terminal;

controlling the second UPF to create a first forwarding tunnel from the second UPF to the first UPF through the PFCP session when it is determined that an indirect forwarding tunnel needs to be created between the S-RAN and the T-RAN; the S-RAN is a base station for providing service for the terminal before the position change occurs, and the T-RAN is a base station for providing service for the terminal after the position change occurs.

Optionally, after controlling the second UPF to create the first forwarding tunnel to the first UPF, the method further comprises:

controlling a first UPF to create a second forwarding tunnel to the S-RAN so that the second forwarding tunnel, the first forwarding tunnel and a third forwarding tunnel between the second UPF and the T-RAN form an indirect forwarding tunnel between the S-RAN and the T-RAN;

in the process of creating the indirect forwarding tunnel, an uplink data message of the terminal is forwarded to a first UPF through an S-RAN so as to be forwarded to a destination through the first UPF, and a downlink data message of the terminal is forwarded to the S-RAN through the first UPF so as to be forwarded to the terminal through the S-RAN.

Optionally, the method further comprises:

after the switching stage is completed, receiving a session context update request sent by an AMF; the switching phase refers to a phase of switching the terminal from an accessed S-RAN to the T-RAN, and the switching phase is started by initiating a switching instruction to the S-RAN through an S-AMF; the switching stage is completed by sending a switching notification instruction through the T-RAN; the S-AMF is an access and mobile management function network element for providing service for the terminal before the position of the terminal changes;

based on the session context update request, starting to send the N3 tunnel information to a second UPF, controlling the second UPF to issue the route information of the terminal, informing the first UPF to delete the route information of the terminal, and starting a first timer and a second timer; wherein, the N3 tunnel refers to a tunnel between the second UPF and the T-RAN for transmitting a data packet;

when the first timer is detected to be overtime, determining that the second UPF finishes receiving the N3 tunnel information, and controlling the first UPF to send a termination mark End Marker to an S-RAN so that the S-RAN can send the termination mark End Marker to the T-RAN through an indirect forwarding tunnel between the S-RAN and the T-RAN;

And when the second timer is detected to be overtime, notifying the first UPF to delete the PFCP session between the first UPF and the SMF and delete the second forwarding tunnel from the first UPF to the S-RAN, and notifying the second UPF to delete the first forwarding tunnel from the second UPF to the first UPF and the third forwarding tunnel between the second UPF and the T-RAN.

Optionally, after the downlink data packet of the terminal is forwarded to the S-RAN by the first UPF in the handover stage, the downlink data packet is forwarded to the first UPF by the S-RAN through the second forwarding tunnel, so that the first UPF forwards the downlink data packet to the second UPF through the first forwarding tunnel, and the second UPF forwards the downlink data packet to the T-RAN for buffering; before the switching stage is completed and the T-RAN receives a termination mark End mark sent by the S-RAN through an indirect forwarding tunnel between the S-RAN and the T-RAN, forwarding a downlink data message buffered by the T-RAN to the terminal by the T-RAN, forwarding a new downlink data message to the S-RAN by a first UPF, then sending the new downlink data message to a first UPF by the S-RAN through a second forwarding tunnel to be forwarded to a second UPF by the first UPF through the first forwarding tunnel, and forwarding the second UPF to the T-RAN through a third forwarding tunnel to be forwarded to the terminal by the T-RAN; and after the T-RAN receives a termination mark End Marker sent by the S-RAN through an indirect forwarding tunnel between the S-RAN and the T-RAN, forwarding the termination mark End Marker to the T-RAN by a second UPF so as to forward the termination mark End Marker to the terminal through the T-RAN;

The uplink data message of the terminal is sent to a first UPF by an S-RAN through a second forwarding tunnel in a switching stage so as to be forwarded to the second UPF by the first UPF through the first forwarding tunnel, and the second UPF is forwarded to the T-RAN through a third forwarding tunnel; and after the switching stage is finished, forwarding the uplink data message cached by the T-RAN and the new uplink data message to a second UPF through the T-RAN so as to forward the uplink data message to a destination through the second UPF.

controlling the second UPF to create a PFCP session with the SMF, and controlling the second UPF to issue the route information of the terminal;

controlling the second UPF to create an N9 tunnel from the second UPF to the first UPF through the PFCP session; the N9 tunnel refers to a tunnel between the second UPF and the first UPF for transmitting data packets.

Optionally, after controlling the second UPF to create the tunnel to the first UPF, the method further comprises:

controlling the first UPF to update the PFCP session so that the downlink data message is forwarded to a second UPF cache by the first UPF through the N9 tunnel; and controlling the first UPF to delete the route of the terminal and starting a third timer;

When the third timer is detected to be overtime, the first UPF is informed to send a termination mark End Marker to the second UPF, so that the second UPF starts to buffer downlink data messages transmitted from the public network;

based on the PFCP session report request sent by the second UPF, controlling the second UPF to update the PFCP session, deleting the N9 tunnel, and notifying the first UPF to delete the PFCP session.

Optionally, the sending opportunity of the PFCP session report request includes:

if a data message can be transmitted between the T-RAN and a second UPF and a downlink data message which is forwarded to a second UPF cache by a first UPF through the N9 tunnel exists in the second UPF, controlling the second UPF to update a PFCP session so that the second UPF preferentially forwards the downlink data message which is forwarded to the second UPF cache by the first UPF through the N9 tunnel to the T-RAN so as to be forwarded to the terminal by the T-RAN; the PFCP session report request is sent to the SMF after the second UPF forwards the downlink data message which is cached by the second UPF and is forwarded to the T-RAN through the N9 tunnel;

if a data message cannot be transmitted between the T-RAN and a second UPF and a downlink data message which is forwarded to a second UPF cache by a first UPF through the N9 tunnel exists in the second UPF, a DDN flow is notified to downlink data initiated by the SMF based on the second UPF, and the second UPF is controlled to establish connection with the T-RAN so that the T-RAN and the second UPF can transmit the data message; and controlling a second UPF to update a PFCP session, so that the second UPF preferentially forwards the downlink data packet forwarded by the first UPF to a second UPF cache through the N9 tunnel to a T-RAN for forwarding by the T-RAN to the terminal; the PFCP session report request is sent to the SMF after the second UPF forwards the downlink data message which is cached by the second UPF and is forwarded to the T-RAN through the N9 tunnel; the DDN process is initiated to the SMF after the second UPF receives an End Marker sent by the first UPF;

And if the downlink data message forwarded to the second UPF cache by the first UPF through the N9 tunnel does not exist in the second UPF, the PFCP session report request is sent to the SMF by the second UPF after receiving a termination mark End Marker sent by the first UPF.

Optionally, before the control of the first UPF to update the PFCP session, the downlink data packet of the terminal is sent to the first UPF cache by a public network; after the first UPF is controlled to update the PFCP session and before the first UPF is informed of sending a termination mark End Marker to a second UPF, forwarding a downlink data message sent to the first UPF cache by a public network to the second UPF cache through an N9 tunnel, and sending a new downlink data message to the first UPF by the public network to be sent to the second UPF cache by the first UPF; after notifying the first UPF to send a termination mark End Marker to a second UPF and before controlling the second UPF to update the PFCP session, forwarding a downlink data message sent by the first UPF to the second UPF cache to a T-RAN by the second UPF so as to be forwarded to the terminal by the T-RAN, and forwarding a new downlink data message to the second UPF cache by a public network; after the PFCP session report request sent by the second UPF is controlled to update the PFCP session, the public network forwards the data message buffered by the second UPF to the T-RAN from the second UPF so as to be forwarded to the terminal by the T-RAN, and the new downlink data message is forwarded to the second UPF from the public network so as to be forwarded to the T-RAN from the second UPF, so that the T-RAN forwards the data message to the terminal;

And after the first UPF is informed to send a termination mark End Marker to a second UPF, the uplink data message of the terminal is generated through the AMF, the T-RAN and the information interaction among the terminals, and the uplink data message of the terminal is forwarded to the second UPF through the T-RAN so as to be forwarded to a destination through the second UPF.

Optionally, the method further comprises:

if the terminal managed by the SMF is not in the service range of the first UPF and the first UPF is judged not to support UPF switching, a relay user plane function network element I-UPF is inserted to provide service for the terminal so that a downlink data message of the terminal is forwarded to the I-UPF by the first UPF, and the I-UPF forwards the downlink data message to the T-RAN so that the T-RAN forwards the downlink data message to the terminal; wherein the terminal is in the service range of the I-UPF.

According to an embodiment of a second aspect of the present application, a path switching device applied in a 5G core network is provided, the device includes:

a determining unit, configured to determine, based on a session update request sent by an access and mobility management function network element AMF, whether a terminal managed by the SMF is in a service range of a first user plane function network element UPF that currently provides a service for the terminal; the session update request is sent by triggering the AMF before the position of the terminal changes or after the position of the terminal changes;

A selecting unit, configured to select a second UPF to replace the first UPF to provide a service for the terminal if the terminal managed by the SMF is not in a service range of the first UPF and it is determined that the first UPF supports UPF switching; the terminal is in the service range of the second UPF;

the creating unit is configured to control the second UPF to create a tunnel to the first UPF, so that before the second UPF replaces the first UPF to send a downlink data packet sent to the terminal to the target base station T-RAN, the downlink data packet of the terminal is forwarded by the first UPF to the second UPF through the tunnel.

the determining unit is specifically configured to:

checking whether the position information of the base station carried by the session updating request is in the service range of the first UPF which is used for providing service for the terminal currently, if so, determining that the terminal is in the service range of the first UPF which is used for providing service for the terminal currently, otherwise, determining that the terminal is not in the service range of the first UPF which is used for providing service for the terminal currently;

And/or the terminal is in an IDLE state CM-IDLE state; when the terminal is in a CM-IDLE state, no signaling connection is established between the terminal and the AMF;

the determining unit is specifically configured to:

checking whether the position information of the terminal carried by the session updating request after the position change is in the service range of the first UPF for providing service for the terminal currently, if so, determining that the terminal is in the service range of the first UPF for providing service for the terminal currently, otherwise, determining that the terminal is not in the service range of the first UPF for providing service for the terminal currently;

and/or, the creation unit is specifically configured to:

controlling the second UPF to create a first forwarding tunnel from the second UPF to the first UPF through the PFCP session when it is determined that an indirect forwarding tunnel needs to be created between the S-RAN and the T-RAN; the S-RAN is a base station for providing service for the terminal before the position of the terminal is changed, and the T-RAN is a base station for providing service for the terminal after the position of the terminal is changed;

And/or, the creation unit is further configured to:

in the process of creating the indirect forwarding tunnel, forwarding an uplink data message of the terminal to a first UPF through an S-RAN (enhanced uplink packet transfer function) to be forwarded to a destination through the first UPF, and forwarding a downlink data message of the terminal to the S-RAN through the first UPF to be forwarded to the terminal through the S-RAN;

and/or, the creation unit is further configured to:

when the second timer is detected to be overtime, notifying the first UPF to delete the PFCP session between the first UPF and the SMF and delete the second forwarding tunnel from the first UPF to the S-RAN, and notifying the second UPF to delete the first forwarding tunnel from the second UPF to the first UPF and the third forwarding tunnel between the second UPF and the T-RAN;

and/or, after the downlink data message of the terminal is forwarded to the S-RAN by the first UPF in the switching stage, the downlink data message is forwarded to the first UPF by the S-RAN through a second forwarding tunnel so as to be forwarded to the second UPF by the first UPF through the first forwarding tunnel, so that the second UPF is forwarded to the T-RAN through a third forwarding tunnel for caching; before the switching stage is completed and the T-RAN receives a termination mark End mark sent by the S-RAN through an indirect forwarding tunnel between the S-RAN and the T-RAN, forwarding a downlink data message buffered by the T-RAN to the terminal by the T-RAN, forwarding a new downlink data message to the S-RAN by a first UPF, then sending the new downlink data message to a first UPF by the S-RAN through a second forwarding tunnel to be forwarded to a second UPF by the first UPF through the first forwarding tunnel, and forwarding the second UPF to the T-RAN through a third forwarding tunnel to be forwarded to the terminal by the T-RAN; and after the T-RAN receives a termination mark End Marker sent by the S-RAN through an indirect forwarding tunnel between the S-RAN and the T-RAN, forwarding the termination mark End Marker to the T-RAN by a second UPF so as to forward the termination mark End Marker to the terminal through the T-RAN;

The uplink data message of the terminal is sent to a first UPF by an S-RAN through a second forwarding tunnel in a switching stage so as to be forwarded to the second UPF by the first UPF through the first forwarding tunnel, and the second UPF is forwarded to the T-RAN through a third forwarding tunnel; after the switching stage is completed, forwarding the uplink data message and the new uplink data message cached by the T-RAN to a second UPF through the T-RAN so as to forward the uplink data message to a destination through the second UPF;

and/or, the creation unit is specifically configured to:

controlling the second UPF to create an N9 tunnel from the second UPF to the first UPF through the PFCP session; the N9 tunnel refers to a tunnel between the second UPF and the first UPF for transmitting data packets;

and/or, the creation unit is further configured to:

Based on a PFCP session report request sent by the second UPF, controlling the second UPF to update the PFCP session, deleting the N9 tunnel, and notifying the first UPF to delete the PFCP session;

and/or, the sending occasion of the PFCP session report request includes:

If the second UPF does not have the downlink data message forwarded to the second UPF cache by the first UPF through the N9 tunnel, the PFCP session reporting request is sent to the SMF by the second UPF after receiving a termination mark End Marker sent by the first UPF;

and/or, before the control of the first UPF to update the PFCP session, the downlink data message of the terminal is sent to the first UPF cache by a public network; after the first UPF is controlled to update the PFCP session and before the first UPF is informed of sending a termination mark End Marker to a second UPF, forwarding a downlink data message sent to the first UPF cache by a public network to the second UPF cache through an N9 tunnel, and sending a new downlink data message to the first UPF by the public network to be sent to the second UPF cache by the first UPF; after notifying the first UPF to send a termination mark End Marker to a second UPF and before controlling the second UPF to update the PFCP session, forwarding a downlink data message sent by the first UPF to the second UPF cache to a T-RAN by the second UPF so as to be forwarded to the terminal by the T-RAN, and forwarding a new downlink data message to the second UPF cache by a public network; after the PFCP session report request sent by the second UPF is controlled to update the PFCP session, the public network forwards the data message buffered by the second UPF to the T-RAN from the second UPF so as to be forwarded to the terminal by the T-RAN, and the new downlink data message is forwarded to the second UPF from the public network so as to be forwarded to the T-RAN from the second UPF, so that the T-RAN forwards the data message to the terminal;

After the first UPF is informed to send a termination mark End Marker to a second UPF, the uplink data message of the terminal is generated through the AMF, the T-RAN and the information interaction among the terminals, and the uplink data message of the terminal is forwarded to the second UPF through the T-RAN so as to be forwarded to a destination through the second UPF;

and/or the selection unit is further configured to:

According to an embodiment of a third aspect of the present application, an electronic device is presented, comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the method according to the first aspect when executing the program.

As can be seen from the above technical solution, in the embodiment of the present application, based on a session update request sent by an access and mobility management function network element AMF, it is determined that a terminal managed by the present SMF is not in a service range of a first UPF and it is determined that the first UPF supports UPF handover, then a second UPF is selected to replace the first UPF to provide services for the terminal, and the second UPF is further controlled to create a forwarding tunnel with the first UPF, so that the second UPF sends, to a target base station T-RAN, a downlink data packet sent to the terminal through the tunnel instead of the first UPF; by creating the tunnel from the first IPF to the second UPF, the downlink data message can be forwarded from the first UPF to the second UPF through the tunnel in the process that the terminal moves from the first UPF service area to the second UPF service area, so that the service of the terminal is not interrupted in the process of switching the forwarding paths of the data message.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.

Fig. 1 is a flowchart of an implementation of a path switching method applied to a 5G core network according to an embodiment of the present application;

fig. 2 is a schematic diagram of a networking structure provided in an embodiment of the present application;

fig. 3 is a signaling interaction diagram provided in an embodiment of the present application;

fig. 4 is a schematic diagram of another networking structure provided in an embodiment of the present application;

fig. 5 is another signaling interaction diagram provided in an embodiment of the present application;

fig. 6 is a schematic structural diagram of an electronic device according to an embodiment of the present application;

fig. 7 is a block diagram of a path switching device applied to a 5G core network according to an embodiment of the present application.

Detailed Description

Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary examples are not representative of all implementations consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with some aspects of the present application as detailed in the accompanying claims.

The terminology used in the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used in this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any or all possible combinations of one or more of the associated listed items.

It should be understood that although the terms first, second, third, etc. may be used herein to describe various information, these information should not be limited by these terms. These terms are only used to distinguish one type of information from another. For example, a first message may also be referred to as a second message, and similarly, a second message may also be referred to as a first message, without departing from the scope of the present application. The word "if" as used herein may be interpreted as "at … …" or "at … …" or "responsive to a determination", depending on the context.

Before the technical solutions proposed in the present application are introduced, the solutions proposed in the related art are first briefly introduced.

UPF (User Plane Function, user plane function network element) in the 5G system is used as the user plane function network element for transmitting uplink and downlink data messages of the terminal. Each UPF has a respective service area due to network planning. During the movement of the terminal, the position change may exceed the service area of the current UPF, and how to guarantee the continuity of the session and the service needs to be considered. For this purpose, 5G systems currently support three session and service continuity modes: SSC Mode (Session and Service Continuity Mode, session and service continuation Mode) 1, SSC Mode 2, and SSC Mode 3.

SSC Mode 1: when the UE (User Equipment) session is established, an anchor point UPF1 is selected, and a PDU (Protocol Data Unit protocol data unit) session User plane with an external data network is established for the UE. When the 5G user terminal moves out of the coverage of the anchor point UPF1, the SMF (Session Management Function, session management function network element) can be inserted into the I-UPF to ensure the continuity of the data service. In the process of moving the 5G user terminal, the user IP address is unchanged, UPF1 is not changed all the time, and the service continuity of the UE is ensured.

SSC Mode 2: the anchor point UPF1 is selected at the time of UE session establishment. When the 5G user terminal moves out of the coverage of the anchor point UPF1, the current PDU session is released first, then a new PDU session is established to select a new anchor point UPF2. During reestablishment of a PDU session, the IP address of the UE may change and the traffic may be interrupted.

SSC Mode 3: the anchor point UPF1 is selected at the time of UE session creation. When the 5G user terminal moves out of coverage of the anchor point UPF1, the UE firstly establishes a new PDU session to select a new anchor point UPF2. After the anchor point UPF1 and the anchor point UPF2 coexist for a period of time, the UE releases the old PDU session to remove the anchor point UPF1. Traffic is not interrupted during the UPF handover but eventually the IP address of the UE will change.

Both SSC Mode 2 and SSC Mode 3 can select a new anchor UPF by physical location, and the anchor UPF changes. However, the service of the SSC Mode 2 is interrupted when the anchor point UPF is changed, and the IP address of the UE is changed when both the SSC Mode 2 and the SSC Mode 3 are required for the upper layer application, which is required to support the user IP address switching, otherwise, the service application of the UE needs to be re-activated. In addition, the terminals on the market at present do not support SSC Mode 2 and SSC Mode 3, and the requirements cannot be met. Although the SSC Mode 1 can meet the requirement that the IP address of the UE does not change, the anchor point UPF does not change during the movement of the UE, and the requirement cannot be met.

The embodiment of the application provides a scheme that an anchor point UPF can be switched along with the position of the UE in the moving process of the UE, the service is kept uninterrupted, and the IP address of the UE is not changed.

The technical solutions in the embodiments of the present application are described in further detail below with reference to the accompanying drawings.

Referring to fig. 1, fig. 1 is a flowchart of a path switching method applied to a 5G core network according to an embodiment of the present application, where the method is applied to SMF in the 5G core network. As shown in fig. 1, the method may include the steps of:

step 101, based on a session update request sent by an AMF (Access and Mobility Management Function access and mobility management function network element), determining whether a terminal managed by the SMF is in a service range of a first UPF currently providing services for the terminal.

For the sake of simplicity of description, the first UPF may be referred to as S-UPF, and will be used hereinafter.

In this embodiment, two scenarios are involved, namely, the CM-CONNECTED state (denoted as CONNECTED state) and the CM-IDLE state (denoted as IDLE state) of the terminal.

In this embodiment, optionally, the terminal is in a CONNECTED CM-CONNECTED state; when the terminal is in the CM-CONNECTED state, signaling connection is established between the terminal and the AMF;

The signaling connection is used for indicating that signaling can be transmitted between the terminal and the AMF.

In this embodiment, determining whether the terminal is in the service range of the first user plane function network element UPF that currently provides services for the terminal through the session update request in the connected state is a conventional method in the related art, and will not be described herein.

In this embodiment, optionally, the terminal is in an IDLE CM-IDLE state; when the terminal is in a CM-IDLE state, no signaling connection is established between the terminal and the AMF;

When the terminal is in the CM-IDLE state, no signaling transmission exists between the terminal and the AMF, and meanwhile, no data message can be transmitted between the terminal and the base station as well as between the base station and the UPF, and if a downlink data message exists, the downlink data message is temporarily buffered in the UPF.

In this embodiment, determining whether the terminal is in the service range of the first user plane function network element UPF currently providing service for the terminal through the session update request in the idle state is a conventional method in the related art, and will not be described herein.

Step 102, if the terminal managed by the SMF is not in the service range of the first UPF and it is determined that the first UPF supports UPF switching, selecting a second UPF to provide services for the terminal instead of the first UPF.

In this embodiment, whether the first UPF supports UPF switching may be directly determined from the configuration of the SMF, which is not described herein.

In this embodiment, the location information of the terminal is in the service range of the second UPF. The first UPF and the second UPF are connected to the same router, and the first UPF, the second UPF and the router all support a dynamic routing protocol, and service areas of the first UPF and the second UPF are not overlapped; selecting a corresponding UPF for providing a service to a terminal based on the terminal is a conventional means in the related art, and will not be described herein.

Optionally, the method further comprises:

In this embodiment, after it is determined that the terminal managed by the SMF is not in the service range of the first UPF and the first UPF does not support UPF switching, a common method in the related art, which is to provide services for the terminal by inserting the relay user plane function network element I-UPF, is not described herein.

For the sake of simplicity of description, the second UPF may be referred to as a T-UPF, and will be used hereinafter.

And step 103, controlling the second UPF to create a tunnel to the first UPF so that the first UPF forwards the downlink data message of the terminal to the second UPF through the tunnel before the second UPF replaces the first UPF to send the downlink data message sent to the terminal to the target base station T-RAN.

In this embodiment, the manner of creating the tunnel is different when the terminal is in the CM-CONNECTED state or the CM-IDLE state, which will be described in detail below.

First, a path switching procedure when the terminal is in the CM-CONNECTED state is described.

In this embodiment, when the terminal is in the CM-CONNECTED state, the controlling the second UPF to create the tunnel to the first UPF includes:

The routing information at least includes the IP address of the terminal, which is different from the IP address allocated by the UPF that issues the routing information in the related art, in this embodiment, the IP address is allocated by the SMF, and since the SMF is unchanged in this embodiment, the IP address of the terminal is allocated by the SMF, and after the location of the terminal is changed, the IP address is unchanged.

In this embodiment, the reason why the route information of the terminal is not issued temporarily is that the current position of the terminal does not enter the service range of the second UPF at this time, if the route is issued at this time, the route needs to be rolled back once the route switching fails, so that the route is issued more stably after the current position of the terminal is within the service range of the second UPF.

In this embodiment, optionally, after controlling the second UPF to create the first forwarding tunnel to the first UPF, the method further includes:

The creation timing and flow of the indirect forwarding tunnel will be described in detail in the following specific embodiments, and are not described herein.

In this embodiment, in the process of creating the indirect forwarding tunnel, the current position of the terminal is always within the service range of the first UPF, and both the uplink and downlink data packets of the terminal are forwarded through the first UPF and the S-RAN.

In this embodiment, optionally, the method may further include:

In this embodiment, the routing information includes at least an IP address of the terminal, where the IP address is allocated by the SMF;

in this embodiment, the first timer duration is determined by the duration required for the second UPF to issue the routing information of the terminal and the duration required for the router to learn the routing information; the second timer timing duration is not less than the first timer timing duration.

In this embodiment, the timeout of the first timer is used to indicate that the router has learned to complete the routing information issued by the second UPF and that the N3 tunnel has been updated, and after the update of the N3 tunnel is completed, the data packet is not required to be forwarded by using the indirect forwarding tunnel; the second timer is overtime and is used for indicating that the switching is completed, at the moment, the PFCP session of the first UPF can be deleted, the first UPF is not used for forwarding the data message, and meanwhile, the second UPF is informed of deleting the indirect forwarding tunnel, so that the occupation of the second UPF resource is reduced.

Further, resources on the S-RAN may be fully released to reduce occupation of radio resources.

In this embodiment, the switching process of the packet forwarding path is as follows:

after the downlink data message of the terminal is forwarded to the S-RAN by the first UPF in the switching stage, the downlink data message is forwarded to the first UPF by the S-RAN through a second forwarding tunnel so as to be forwarded to the second UPF by the first UPF through the first forwarding tunnel, and the second UPF is forwarded to the T-RAN cache through a third forwarding tunnel; before the switching stage is completed and the T-RAN receives a termination mark End mark sent by the S-RAN through an indirect forwarding tunnel between the S-RAN and the T-RAN, forwarding a downlink data message buffered by the T-RAN to the terminal by the T-RAN, forwarding a new downlink data message to the S-RAN by a first UPF, then sending the new downlink data message to a first UPF by the S-RAN through a second forwarding tunnel to be forwarded to a second UPF by the first UPF through the first forwarding tunnel, and forwarding the second UPF to the T-RAN through a third forwarding tunnel to be forwarded to the terminal by the T-RAN; and after the T-RAN receives a termination mark End Marker sent by the S-RAN through an indirect forwarding tunnel between the S-RAN and the T-RAN, forwarding the termination mark End Marker to the T-RAN by a second UPF so as to forward the termination mark End Marker to the terminal through the T-RAN;

In this embodiment, the indirect forwarding tunnel is created, and when the current position of the terminal starts to move to the service range of the second UPF, in order to ensure continuity of the service when the UPF is switched and no packet loss occurs, the downlink data packet is forwarded from the first UPF to the S-RAN, and then is not forwarded to the terminal, but is forwarded to the T-RAN through the indirect forwarding tunnel for temporary buffering; meanwhile, the uplink data message of the terminal is not directly uploaded to the data network through the first UPF, but is forwarded to the T-RAN cache through the indirect forwarding tunnel, and is forwarded after the terminal moves to the service range of the second UPF.

In this embodiment, the second UPF issues the routing information of the terminal, and the router also needs a certain time when learning the routing information, and when the router does not learn the routing information, the router only can forward the downlink data packet to the route issued by the first UPF, that is, to the first UPF, so that the router still needs to forward the data packet to the T-RAN by using the indirect forwarding tunnel and then transmit the data packet to the terminal.

In this embodiment, after controlling the second UPF to issue the route information of the terminal, the first UPF is notified to delete the route of the terminal, and the first UPF is controlled not to delete the PFCP session. After deleting the route of the terminal, the forwarding table entry of the data packet in the router still exists, and because the route information issued by the second UPF is not learned by the router at this time, the downlink data packet is still forwarded from the first UPF to the S-RAN according to the forwarding table entry, and then forwarded to the T-RAN through the indirect forwarding tunnel and retransmitted to the terminal, so that the purpose of not deleting the PFCP session is to temporarily reserve the indirect forwarding tunnel in fact.

And finally, switching forwarding paths from the first UPF to the second UPF is completed, and both the uplink and downlink data messages of the terminal are forwarded by the second UPF and the T-RAN.

The above is the path switching procedure when the terminal is in the CM-CONNECTED state, and the path switching procedure when the terminal is in the CM-IDLE state is described below.

In this embodiment, when the terminal is in the CM-IDLE state, controlling the second UPF to create the tunnel to the first UPF includes:

In this embodiment, optionally, after controlling the second UPF to create the tunnel to the first UPF, the method further includes:

The process of controlling the first UPF to update the PFCP session, controlling the first UPF to delete the route of the terminal, starting the third timer, deleting the N9 tunnel, and deleting the PFCP session is similar to that of the CM-CONNECTED state, and will not be described in detail in the following specific embodiments.

In this embodiment, optionally, the sending opportunity of the PFCP session report request includes:

The above cases of the sending timing of the PFCP session report request will be described in detail in the following specific embodiments, which are not described herein.

before the control of the first UPF to update the PFCP session, the downlink data message of the terminal is sent to the first UPF cache by a public network; after the first UPF is controlled to update the PFCP session and before the first UPF is informed of sending a termination mark End Marker to a second UPF, forwarding a downlink data message sent to the first UPF cache by a public network to the second UPF cache through an N9 tunnel, and sending a new downlink data message to the first UPF by the public network to be sent to the second UPF cache by the first UPF; after notifying the first UPF to send a termination mark End Marker to a second UPF and before controlling the second UPF to update the PFCP session, forwarding a downlink data message sent by the first UPF to the second UPF cache to a T-RAN by the second UPF so as to be forwarded to the terminal by the T-RAN, and forwarding a new downlink data message to the second UPF cache by a public network; after the PFCP session report request sent by the second UPF is controlled to update the PFCP session, the public network forwards the data message buffered by the second UPF to the T-RAN from the second UPF so as to be forwarded to the terminal by the T-RAN, and the new downlink data message is forwarded to the second UPF from the public network so as to be forwarded to the T-RAN from the second UPF, so that the T-RAN forwards the data message to the terminal;

The above is the path switching procedure when the terminal is in the CM-IDLE state.

This concludes the description of the 5G core network path switching flowchart in fig. 1.

As can be seen from the above technical solutions, in the embodiments of the present application, based on a session update request sent by an access and mobility management function network element AMF, it is determined that a terminal managed by the present SMF is not in a service range of a first UPF, and then a second UPF is selected to provide services for the terminal instead of the first UPF, and the second UPF is further controlled to create a forwarding tunnel with the first UPF, so that the second UPF sends, to a target base station T-RAN, a downlink data packet sent to the terminal through the tunnel instead of the first UPF; by creating the tunnel from the first IPF to the second UPF, the downlink data message can be forwarded from the first UPF to the second UPF through the tunnel in the process that the terminal moves from the first UPF service area to the second UPF service area, so that the service of the terminal is not interrupted in the process of switching the forwarding paths of the data message. Further, since the IP addresses of the terminals are all allocated by the SMF in this embodiment, but the SMF in this embodiment is unchanged all the time, this embodiment also realizes that the IP addresses of the terminals are not changed while the UPF is switched.

Two scenarios are described in detail below in connection with fig. 2-5.

Based on the networking structure shown in fig. 2, the following describes the present embodiment 1 by the flow shown in fig. 3:

referring to fig. 3, fig. 3 is a signaling interaction diagram of embodiment 1 of the present application. The scenario is that a UPF handover occurs due to a location change when a UE (User Equipment) is in a CM-CONNECTED state. As shown in fig. 3, the process may include the steps of:

step 300, the UE initiates a PDU (Protocol Data Unit ) session creation procedure to the S-RAN serving the UE.

In this embodiment, the terminal UE initiates a PDU session creation procedure to the S-RAN serving the UE, and finally establishes a PDU session. The procedure of establishing the PDU session is a common method in the related art, and will not be described herein.

The S-UPF creates a PFCP session, establishes contact with the SMF, and issues routing information of the UE.

The SMF distributes the IP address of the UE in the process of creating the PDU session, and informs the distributed IP address to the S-UPF, and the route information issued by the S-UPF carries the IP address of the UE, so that the router can forward the data message of the corresponding IP address after acquiring the route information.

As an embodiment, the S-UPF may issue the routing information of the UE through RIP (Routing Information Protocol ) or OSPF (Open Shortest Path First, open shortest path first) protocol, which is not limited in this application.

In step 301, the S-RAN sends a handover required message to the S-AMF.

For ease of description, the handover required message may be denoted herein as Handover Required, for one embodiment.

The S-RAN sends a handover required message to the S-AMF in step 301, so that the S-AMF selects the T-AMF based on the handover required message, where the handover required message carries location information of the target base station to be handed over, in step 302.

Step 302, the S-AMF selects a T-AMF based on a handover request sent by the S-RAN.

In this embodiment, after receiving the handover request message, the S-AMF selects a corresponding T-AMF according to the target base station information carried by the S-AMF.

In step 303, the s-AMF sends a create UE context request message to the T-AMF.

In this embodiment, after selecting a corresponding T-AMF, the S-AMF sends a request for creating UE context to the T-AMF, and informs the T-AMF of the UE context in the S-AMF.

For ease of description, the create UE context request information may be referred to as namf_communication_ CreateUE Context Request, as an embodiment.

The t-AMF sends a PDU session context modification request message to the SMF, step 304.

In this embodiment, after receiving the UE context creation request information sent by the SMF, the T-AMF sends PDU session context modification request information to the SMF, and associates the T-AMF with the SMF, so that the T-AMF can control the SMF, and at the same time inform the SMF of the UE context information.

For the sake of description, the PDU session context modification request information may be referred to herein as nsmf_pduse_ UpdateSMContext Request, for convenience of description.

The implementation methods of steps 301 to 304 are all common methods in the related art, and are not described herein.

In step 305, after receiving the UE context modification request information, the SMF selects a UPF according to the target base station information to which the UE is to be handed over.

In this embodiment, the SMF determines whether the target base station is beyond the service range of the current service UPF according to the target base station information to which the UE is to be handed over. If the service range of the current service UPF is exceeded, judging whether the UPF can be changed; if not, I-UPF is inserted (the subsequent flow is consistent with SSC Mode 1 protocol flow, and is not repeated here); if it can be changed, the SMF selects a new UPF as the T-UPF to continue the subsequent process. The local configuration of the SMF can determine whether the UPF can be changed, and the selected T-UPF is still within the service range of the SMF.

The process of selecting the T-UPF by the SMF is a common method in the related art, and will not be described herein.

Step 306, the t-UPF creates a PFCP session.

In this embodiment, after the T-UPF is selected, the SMF controls the T-UPF to create a PFCP session, and associates the T-UPF with the SMF, at which time the T-UPF temporarily does not publish the routing information of the UE. Since the UE has not been switched to the destination base station T-RAN at this time, the link between the T-RAN and the T-UPF has not been created yet, and it is not necessary to issue the routing information of the UE.

In step 307, the smf replies to the T-AMF with PDU session context modification reply information.

In this embodiment, after the PFCP session of the T-UPF is successfully created, the SMF replies to the T-AMF with PDU session context modification reply information, informing the T-AMF that the PDU session context modification is successful.

For ease of description, the PDU session context modification reply information may be referred to as nsmf_pduse_ UpdateSMContext Response, as an embodiment.

The T-AMF sends a handover request message to the T-RAN, step 308.

In this embodiment, after the T-AMF receives the PDU session context modification reply information sent by the SMF, the T-AMF sends a handover request to the T-RAN, and informs the T-RAN terminal UE to switch to the T-RAN to transmit a data packet, so that the T-RAN allocates resources for the UE in advance.

For ease of description, the Handover Request message is referred to as a Handover Request, as an embodiment.

In step 309, the T-RAN replies to the T-AMF with a handover request confirm message.

In this embodiment, after receiving a handover request message sent by the T-AMF, the T-RAN replies a handover request acknowledgement message to the T-AMF, where the acknowledgement message carries a TEID (Tunnel Endpoint Identifier ), and the RAN can identify a PDU session established by the terminal according to the TEID, and at the same time, the T-RAN creates an indirect forwarding tunnel to the T-UPF.

For ease of description, the handover request acknowledge message may be denoted as Handover Request Ack, as an embodiment.

The t-AMF sends PDU session context modification request information to the SMF, step 310.

In this embodiment, after receiving the handover request acknowledgement message sent by the T-RAN, the T-AMF sends PDU session context modification request information to the SMF, and informs the SMF of the PDU session information, where the UE context information includes the TEID information described above.

For convenience of description, the PDU session context modification request information may be referred to as nsmf_pduse_ UpdateSMContext Request, as an embodiment.

In step 311, the smf controls the T-UPF to create an indirect forwarding tunnel.

In this embodiment, the SMF informs the T-UPF of creating an indirect forwarding tunnel to the S-UPF, and returns the indirect forwarding tunnel information to the SMF after the T-UPF creates the indirect forwarding tunnel to the S-UPF.

In step 312, the SMF controls the S-UPF to create an indirect forwarding tunnel.

In this embodiment, the SMF issues the indirect forwarding tunnel information returned by the T-UPF to the S-UPF, and the S-UPF creates an indirect forwarding tunnel to the S-RAN, and returns the indirect forwarding tunnel information to the SMF.

In step 313, the smf replies to the T-AMF with PDU session context modification reply information.

In this embodiment, after receiving the indirect forwarding tunnel creation information returned by the S-UPF, the SMF replies to the T-AMF with PDU session context modification reply information, informing the T-AMF that the PDU session context modification is successful.

In step 314, the T-AMF sends create UE context reply information to the S-AMF.

In this embodiment, the T-AMF sends the create UE context reply information to the S-AMF, informing the S-AMF that the UE context information SMF sent in step 303 is all known.

For ease of description, the create UE context reply information may be referred to as namf_communication_ CreateUE Context Response, as an embodiment.

Steps 300 to 314 may be referred to as a handover preparation phase, in which the UE has not moved beyond the service area of the S-UPF, so that the uplink and downlink data packets of the UE are still forwarded by the S-UPF and the S-RAN.

Step 315, the S-AMF sends a handover instruction message informing the S-RAN that the target base station is ready for handover.

In this embodiment, after receiving the context reply information of the creating UE sent by the T-AMF, the S-AMF knows that the indirect forwarding tunnel has been created, and sends a handover instruction message to the S-RAN at this time, to inform the S-RAN that the target base station T-RAN is ready for handover.

For ease of description, the Handover Command message may be referred to as a Handover Command, for one embodiment.

In step 316, the S-RAN sends a handover instruction message to the UE.

In this embodiment, after receiving the handover command sent by the S-AMF, the S-RAN sends a handover command to the UE, informing the UE that the UE is about to switch to the T-RAN.

At this time, if the S-RAN and the T-RAN have the direct forwarding tunnel created, the downlink data packet is sent to the S-RAN by the S-UPF, and the S-RAN is sent to the T-RAN, where the T-RAN buffers. If the S-RAN and the T-RAN have the establishment of an indirect forwarding tunnel, the downlink data message is sent to the S-RAN by the S-UPF, the S-RAN is sent to the S-UPF, the S-UPF forwards the data message to the T-UPF through the indirect forwarding tunnel, and the T-UPF forwards the data message to the T-RAN for caching. The uplink data message also needs to be forwarded by the S-RAN to the T-RAN buffer via an indirect forwarding tunnel or a direct forwarding tunnel.

In step 317, the ue sends a handover confirm message to the T-RAN.

In this embodiment, after receiving a handover command sent by the S-RAN, the UE moves to a service range of the target base station T-UPF, and sends a handover confirm message to the T-RAN. At this time, the UE forwards the uplink data packet buffered in the T-RAN in step 316 using a new N3 tunnel (T-RAN to T-UPF), and the uplink data packet newly generated by the UE may also be forwarded through the N3 tunnel, and the downlink data packet buffered in step 316 is forwarded to the UE.

For ease of description, the Handover Confirm message may be referred to as a Handover Confirm, as an embodiment.

In step 318, the T-RAN sends a handover notification message to the T-AMF.

In this embodiment, after the T-RAN receives the handover confirm message sent by the UE, it is known that the UE has moved to within the service range of the T-RAN, and the T-RAN sends the handover notify message to notify that the T-AMF handover is successful.

In step 318a, after receiving the handover notification message sent by the T-RAN, the T-AMF sends an N2 modification notification message to the S-AMF to notify the S-AMF that the handover is completed.

In step 318b, after receiving the N2 modification notification message sent by the T-AMF, the s-AMF sends an N2 modification acknowledgement message to the T-AMF, and starts a Holding Timer.

In step 319, the t-AMF sends PDU session context modification request information to the SMF.

In this embodiment, after receiving the handover notification message, the T-AMF sends PDU session context modification request information to the SMF, and informs the SMF of the handover completion information.

For convenience of description, the PDU session context modification request information may be denoted as nsmf_pduse_ UpdateSMContext Request, as an embodiment.

At step 320, the SMF initiates PFCP session modification with the T-UPF.

In this embodiment, after receiving the PDU session context modification request information sent by the T-AMF and after that, the SMF controls the T-UPF to initiate PFCP session modification, and notifies the T-UPF to update the N3 tunnel, associate the T-UPF with the T-RAN, and after the N3 tunnel is completed, the T-UPF may directly transmit the downlink data packet received by the data network to the T-RAN through the N3 tunnel to forward to the UE; meanwhile, the T-UPF issues the route of the UE and returns a PFCP session modification response message to the SMF.

At step 321, the SMF initiates PFCP session modification with the S-UPF.

In this embodiment, after knowing that the routing information has been issued, the SMF controls the S-UPF to initiate PFCP session modification, and notifies the S-UPF to delete the route of the UE, so that the PFCP session is not deleted. The SMF starts an End Marker Timer (the Timer duration depends on the duration of the network element publishing route and the duration learned by the correspondent router) and a Holding Timer. The S-UPF returns the modification information to the SMF after deleting the route.

After deleting the route of the UE, the S-UPF still exists in the forwarding table entry of the data packet in the router due to the PFCP session is not deleted, and the route information issued by the T-UPF is not learned by the router at this time, and the downlink data packet is still forwarded from the S-UPF to the S-RAN according to the forwarding table entry, and then forwarded to the T-RAN through the indirect forwarding tunnel for retransmission to the terminal.

At step 322, the smf replies to the T-AMF with PDU session context modification reply information.

In this embodiment, after receiving the modification information returned by the S-UPF, the SMF replies to the T-AMF with PDU session context modification reply information, informing the T-AMF that the PDU session context modification is successful, and that the routing information issued by the S-UPF has been deleted. As one embodiment, the PDU session context modification reply information may be denoted as nsmf_pduse_ UpdateSMContext Response.

Step 323, SMF initiates PFCP session modification with S-UPF.

In this embodiment, when the End Marker timer times out, the SMF initiates PFCP session modification with the S-UPF, and the S-UPF sends an End Marker message to notify the S-RAN N3 that tunnel switching is completed, that is, the S-UPF switches to the T-UPF, and the router has already learned the routing information sent by the T-UPF.

After the N3 tunnel switching is completed, the router switches the downlink data path to be forwarded from the T-UPF to the T-RAN, and then the downlink data path is forwarded to the UE by the T-RAN without using an indirect forwarding tunnel.

Step 324a, the SMF initiates PFCP session modification with the S-UPF.

In this embodiment, the Holding Timer times out in step 321, the SMF notifies the S-UPF to delete the PFCP session,

at step 324b, the SMF initiates PFCP session modification with the T-UPF.

In this embodiment, the Holding Timer in step 321 times out, and the SMF simultaneously notifies the T-UPF to delete the indirect forwarding tunnel.

The Holding Timer overtime indicates that path switching is completed, at the moment, the S-UPF is controlled to delete the PFCP session, so that the occupation of S-UPF resources is reduced, and meanwhile, the T-UPF is controlled to delete the indirect forwarding tunnel, so that the occupation of the T-UPF resources is reduced.

Step 325, the S-AMF initiates a UE context release with the S-RAN.

In this embodiment, when the Holding Timer in step 318 times out, the S-AMF notifies the S-RAN to release the N2 link resource, and the link from the S-UPF to the S-RAN is no longer used for transmitting the data packet.

This concludes the description of the signaling diagram of fig. 3. In this embodiment, the IP address of the terminal is allocated by the SMF, and an indirect forwarding tunnel from the T-UPF to the S-UPF is created, and the downlink data packet originally sent to the S-RAN is forwarded to the T-RAN for buffering by the indirect forwarding tunnel, so that after the UPF is switched, the data packet buffered by the T-RAN is forwarded first, and then the downlink data packet directly forwarded to the T-UPF is forwarded, so that the service can be switched without loss and the IP address of the terminal is not changed when the UPF is switched, and the problem that the IP address is changed in the related art, resulting in a higher requirement for an upper layer application is solved.

Based on the networking structure shown in fig. 4, the following describes the present embodiment 2 by the flow shown in fig. 5:

referring to fig. 5, fig. 5 is a signaling interaction diagram of embodiment 2 of the present application. The scenario is that a UPF handover occurs due to a location change when the terminal UE is in a CM-IDLE state (IDLE state). As shown in fig. 5, the process may include the steps of:

in step 501, the ue initiates a mobile registration procedure.

In this embodiment, the current location of the terminal UE is not already in the service range of the S-UPF, and the UE sends a registration request to the T-RAN currently serving the UE, and finally completes registration, and confirms that the AMF currently serving the terminal is the T-AMF.

For ease of description, the registration request may be denoted as Registration Request, for one embodiment.

The mobile registration process is a common method in the related art, and will not be described herein.

At step 502, the user context of the S-AMF is migrated to the T-AMF.

In this embodiment, after the UE completes registration, the T-AMF identifies that the UE carries an identifier of the S-AMF, that is, identifies that the S-AMF is an AMF that provides services for the UE before the location of the UE changes, requests the S-AMF to migrate the user context to the T-AMF, and the S-AMF replies to the user context migration request message to send the message carrying the UE information in the S-AMF to the T-AMF.

In step 503, the T-AMF notifies the S-AMF that registration is complete.

In this embodiment, the T-AMF sends a notification to the S-AMF that registration is completed after receiving the user context migration reply of the S-AMF.

For ease of description, the completion registration notification message sent by the T-AMF to the S-AMF may be referred to as Namf communication registration status update, as an embodiment.

In step 504, the T-AMF registers in the UDM.

In this embodiment, the T-AMF serving as the new AMF registers the information carried by itself in the UDM, informs the UDM of the information carried by itself, and replies the T-AMF registration information to the UDM.

The procedure of registering in the UDM is a common method in the related art, and will not be described herein.

In step 505, the t-AMF sends a PDU session context modification request to the SMF.

In this embodiment, after registration in the UDM is completed, the T-AMF associates the T-AMF with the SMF and brings information about the UE in the T-AMF to the SMF through PDU session context modification.

In step 506, the smf selects a UPF according to the received UE information.

In this embodiment, after receiving the PDU session context modification request message of the AMF, the SMF determines, according to the current location of the UE, whether the service range of the current service UPF is exceeded. If the service range of the current service UPF is exceeded, judging whether the UPF can be changed. If not, I-UPF is inserted (the subsequent flow is consistent with the protocol flow and will not be described here). If it can be changed, the SMF selects a new UPF as the T-UPF to continue the subsequent process.

The SMF selects the T-UPF according to the relevant information of the UE as a common method in the related art, which is not described herein.

In step 507, the T-UPF creates a PFCP session.

In this embodiment, after the T-UPF is selected, the SMF controls the T-UPF to create a PFCP session, and at the same time controls the T-UPF to create an N9 tunnel for receiving the downlink data packet buffered by the S-UPF, and issues the route of the UE, where the downlink data packet is still issued to the S-UPF for buffering because the route issued by the S-UPF has not been deleted yet. After the above steps are completed, the T-UPF will create an N9 tunnel, and return the PFCP session modification response message to the SMF.

Step 508, the S-UPF updates the PFCP session.

In this embodiment, after the SMF receives a message that the T-UPF has created an N9 tunnel and published routing information, it controls the S-UPF to update the PFCP session, updates the N3 downlink tunnel to be the N9 tunnel of the T-UPF, and sets the SNDEM flag bit; controlling the S-UPF to delete the route of the UE released before the S-UPF; and simultaneously starting an End marker timer (the duration of the timer depends on the duration of the UPF release route and the learning route of the opposite router). The S-UPF returns the result of updating the PFCP session to the SMF after performing the above steps.

The SNDEM mark bit is carried in the updating PFCP session request sent by the SMF to the S-UPF, and the mark bit enables the S-UPF to send the End marker mark to the T-UPF after the End marker timer is overtime.

At this time, since the router has not learned the route issued by the T-UPF, the downstream data packet needs to be forwarded from the S-UPF to the T-UPF for buffering through the N9 tunnel.

Step 509, the pdu session context modifies the reply.

In this embodiment, after the SMF receives the result of updating the PFCP session by the S-UPF, the SMF replies to the PDU session context modification message of step 505. In the scenario where the UE does not request activation of user plane resources, there is no need to encapsulate the PDU session resource creation request (PDU Session Resource Setup Request) message in the response message. The UE has a scene of requesting to activate user plane resources, and needs to encapsulate PDU session resource creation request information in response information.

The scenario of requesting to activate the user plane refers to recovering the connection between the base station and the UPF, so that the data packet of the user can be forwarded.

In step 510a, the S-UPF sends the buffered data message to the T-UPF.

In this embodiment, the SMF controls the S-UPF to send the buffered data packet (if any) to the T-UPF for buffering through the N9 tunnel created in step 507.

In step 510b, the SMF notifies the S-UPF to send an End Marker to the T-UPF.

In this embodiment, after the End Marker timer in step 508 times out, the SMF notifies the S-UPF to send an End Marker termination flag to the T-UPF, which indicates that the router has learned the routing information issued by the T-UPF, so that the T-UPF does not need to receive the data packet sent by the S-UPF any more, and so that the T-UPF knows that all the data packets cached in the S-UPF have been forwarded to the T-UPF when receiving the signaling carrying the End Marker flag.

In step 511, the T-AMF interacts with the T-RAN, the UE, messages.

In this embodiment, at this time, the T-AMF performs message interaction with the T-RAN and the UE, and at this time, the UE and the T-RAN can transmit data messages, and from this step, an uplink data message will only appear in this scenario.

Step 512, pdu session context modification.

In this embodiment, the T-AMF informs the SMF of information carried by the T-AMF after the message interaction, and the SMF replies to the T-AMF context modification information.

In step 513a_1, the ue requests to activate the user plane, the base station replies a PDU session resource setting reply (PDU Session Resource Setup Response) message, and the SMF updates the T-UPF session, only updates the FAR of the N9 tunnel, and controls the T-UPF to forward preferentially the data packet forwarded by the S-UPF to the T-UPF buffer through the N9 tunnel.

Step 513a_2, after the T-UPF transmits the data message which is forwarded to the T-UPF buffer memory by the S-UPF through the N9 tunnel, the T-UPF initiates a PFCP session notification flow to inform that the SMF transmits the data message which is forwarded to the T-UPF buffer memory by the S-UPF through the N9 tunnel is completed; the T-UPF directly initiates a PFCP session notification flow in a scene that the T-UPF does not receive the cached data of the S-UPF;

step 513a_3, after receiving the PFCP session notification message, the SMF updates the PFCP session of the T-UPF, deletes the N9 tunnel, and the T-UPF starts forwarding the downlink data of the N6 interface (data network to T-UPF);

At this time, path switching is completed, and both uplink and downlink data messages are forwarded through the T-RAN and the T-UPF.

In step 513a_4, after determining that the T-UPF starts forwarding the downlink data of the N6 interface, the SMF notifies the S-UPF to delete the PFCP session, so as to reduce the occupation of the S-UPF resource.

Step 513b_1, if the UE does not request to activate the user plane, the S-UPF does not cache data, and after receiving the End Marker of the S-UPF, the T-UPF initiates a PFCP session notification procedure;

step 513b_2, after receiving the PFCP session notification message, the SMF updates the PFCP session of the T-UPF and deletes the N9 tunnel;

in step 513b_3, the SMF notifies the S-UPF to delete the PFCP session.

The flow of steps 513b_1 to 513b_3 is similar to that of steps 513a_2 to 513b_4, and will not be repeated here.

In step 513c_1, if the UE does not request to activate the user plane, the S-UPF has cached data, and after receiving the End Marker of the S-UPF, the T-UPF initiates a DDN (Downlink Data Notification ) procedure. Wherein the DDN procedure is used to reactivate the user plane.

After the user plane of the PDU session is recovered, steps 513c_2 to 513c_5 are performed in steps 513a_1 to 513a_4, and the t-UPF preferentially sends the buffered data packet of the N9 tunnel, which is not described herein.

This concludes the description of the signaling interaction diagram of fig. 5. In this embodiment, the IP address of the terminal is allocated by the SMF, and an N9 tunnel from the T-UPF to the S-UPF is created, and the downstream data packet originally sent to the S-UPF is forwarded to the T-UPF for buffering by the N9 tunnel, so that after the UPF is switched, the downstream data packet forwarded to the T-UPF by the S-UPF through the N9 tunnel is forwarded first, and then the downstream data packet directly sent to the T-UPF by the data network is forwarded.

Fig. 6 shows a schematic structural diagram of an electronic device provided in an embodiment of the present application. Referring to fig. 6, at the hardware level, the electronic device includes a processor, an internal bus, a network interface, a memory, and a nonvolatile memory, and may include hardware required by other services. The processor reads the corresponding computer program from the nonvolatile memory into the memory and then runs the computer program to form the terminal interaction device on the logic level. Of course, other implementations, such as logic devices or combinations of hardware and software, are not excluded from the present application, that is, the execution subject of the following processing flows is not limited to each logic unit, but may be hardware or logic devices.

Referring to fig. 7, fig. 7 is a block diagram of a path switching device applied to a 5G core network according to an embodiment of the present application. As shown in fig. 7, the path switching apparatus applied to the 5G core network may include a determining unit 701, a selecting unit 702, and a creating unit 703. Specifically, the device comprises:

a determining unit 701, configured to determine, based on a session update request sent by an access and mobility management function network element AMF, whether a terminal managed by the SMF is in a service range of a first user plane function network element UPF that currently provides a service for the terminal; the session update request is sent by triggering the AMF before the position of the terminal changes or after the position of the terminal changes;

A selecting unit 702, configured to select a second UPF to provide a service for the terminal instead of the first UPF if the terminal managed by the SMF is not in a service range of the first UPF and it is determined that the first UPF supports UPF switching; the terminal is in the service range of the second UPF;

a creating unit 703, configured to control the second UPF to create a tunnel to the first UPF, so that before the second UPF replaces the first UPF to send a downlink data packet sent to the terminal to the target base station T-RAN, the downlink data packet of the terminal is forwarded by the first UPF to the second UPF through the tunnel.

the determining unit 701 is specifically configured to:

and/or, the creation unit 703 is specifically configured to:

controlling the second UPF to create a first forwarding tunnel from the second UPF to the first UPF through the PFCP session when it is determined that an indirect forwarding tunnel needs to be established between the S-RAN and the T-RAN; the S-RAN is a base station for providing service for the terminal before the position of the terminal is changed, and the T-RAN is a base station for providing service for the terminal after the position of the terminal is changed;

And/or, the creation unit 703 is further configured to:

in the process of establishing the indirect forwarding tunnel, forwarding an uplink data message of the terminal to a first UPF through an S-RAN (enhanced uplink packet transfer function) to be forwarded to a destination through the first UPF, and forwarding a downlink data message of the terminal to the S-RAN through the first UPF to be forwarded to the terminal through the S-RAN;

and/or, the creation unit 703 is further configured to:

and/or, the creation unit 703 is specifically configured to:

and/or, the creation unit 703 is further configured to:

and/or, the sending occasion of the PFCP session report request includes:

and/or, the selecting unit 702 is further configured to:

So far, the description of the path switching apparatus applied to the 5G core network in fig. 7 is completed.

Correspondingly, in the present embodiment, the present application further provides a computer readable storage medium, where a plurality of computer instructions are stored on the computer readable storage medium, where the computer instructions can implement a method disclosed in the foregoing examples of the present application when the computer instructions are executed.

By way of example, the above-described computer-readable storage media may be any electronic, magnetic, optical, or other physical storage device that can contain or store information, such as executable instructions, data, and the like. For example, the computer readable storage medium may be: RAM (Radom Access Memory, random access memory), volatile memory, non-volatile memory, flash memory, a storage drive (e.g., hard drive), a solid state drive, any type of storage disk (e.g., optical disk, dvd, etc.), or a similar storage medium, or a combination thereof.

The system, apparatus, module or unit set forth in the above embodiments may be implemented in particular by a computer chip or entity, or by a product having a certain function. A typical implementation device is a computer, which may be in the form of a personal computer, laptop computer, cellular telephone, camera phone, smart phone, personal digital assistant, media player, navigation device, email device, game console, tablet computer, wearable device, or a combination of any of these devices.

For convenience of description, the above devices are described as being functionally divided into various units, respectively. Of course, the functions of each element may be implemented in one or more software and/or hardware elements when implemented in the present application.

It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, embodiments of the present application may take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

Moreover, these computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

The foregoing description of the preferred embodiments of the present invention is not intended to limit the invention to the precise form disclosed, and any modifications, equivalents, improvements and alternatives falling within the spirit and principles of the present invention are intended to be included within the scope of the present invention.

Claims

1. A path switching method applied to a 5G core network, wherein the method is applied to a session management function network element SMF in the 5G core network, the method comprising:

The SMF managed terminal is in a CONNECTED CM-CONNECTED state; when the terminal is in a CM-CONNECTED state, signaling connection is established between the terminal and an access and mobility management function network element AMF;

checking whether the position information of a base station accessed after the position change of the terminal carried by a session update request sent by the AMF is in the service range of a first user plane function network element UPF for providing service for the terminal currently; the session update request is used for indicating that the terminal is about to generate position change, and the session update request at least carries the position information of the base station accessed after the terminal generates position change;

if not, and judging that the first UPF supports UPF switching, selecting a second UPF to replace the first UPF to provide service for the terminal; the terminal is in the service range of the second UPF;

based on the session context update request, starting to send N3 tunnel information to a second UPF, controlling the second UPF to issue routing information of the terminal, and informing a first UPF to delete the routing information of the terminal so that the second UPF replaces the first UPF to send a downlink data message sent to the terminal to a target base station T-RAN; wherein, the N3 tunnel refers to a tunnel between the second UPF and the T-RAN for transmitting a data packet;

or,

the SMF managed terminal is in an IDLE CM-IDLE state; when the terminal is in a CM-IDLE state, no signaling connection is established between the terminal and the AMF;

checking whether the position information of the terminal after the position change carried by the session update request sent by the AMF is in the service range of a first UPF for providing service for the terminal currently or not after the position change of the terminal is triggered; the session update request is used for indicating that the terminal has changed in position, and the session update request carries the position information of the terminal after the position change;

controlling the first UPF to update the PFCP session so that the downlink data message is forwarded to a second UPF cache by the first UPF through the N9 tunnel; and controlling the first UPF to delete the route of the terminal so that the second UPF replaces the first UPF to send a downlink data message sent to the terminal to the target base station T-RAN.

2. The method of claim 1, wherein when the terminal is in a CM-CONNECTED state, after controlling the second UPF to create a first forwarding tunnel from the second UPF to the first UPF, the method further comprises:

3. The method of claim 1, wherein when the terminal is in the CM-CONNECTED state, after informing the first UPF to delete the routing information of the terminal, the method further comprises:

starting a first timer and a second timer;

when the first timer is detected to be overtime, determining that the second UPF finishes receiving the N3 tunnel information, and controlling the first UPF to send a termination mark EndMarker to an S-RAN so that the S-RAN can send the termination mark EndMarker to the T-RAN through an indirect forwarding tunnel between the S-RAN and the T-RAN;

4. A method according to claim 3, wherein when the terminal is in the CM-CONNECTED state, the downlink data packet of the terminal is forwarded to the S-RAN by the first UPF in the handover stage, and then is sent to the first UPF by the S-RAN through the second forwarding tunnel to be forwarded to the second UPF by the first UPF through the first forwarding tunnel, so that the second UPF is forwarded to the T-RAN buffer through the third forwarding tunnel; before the switching stage is completed and the T-RAN receives a termination mark End mark sent by the S-RAN through an indirect forwarding tunnel between the S-RAN and the T-RAN, forwarding a downlink data message buffered by the T-RAN to the terminal by the T-RAN, forwarding a new downlink data message to the S-RAN by a first UPF, then sending the new downlink data message to a first UPF by the S-RAN through a second forwarding tunnel to be forwarded to a second UPF by the first UPF through the first forwarding tunnel, and forwarding the second UPF to the T-RAN through a third forwarding tunnel to be forwarded to the terminal by the T-RAN; and after the T-RAN receives a termination mark End Marker sent by the S-RAN through an indirect forwarding tunnel between the S-RAN and the T-RAN, forwarding the termination mark End Marker to the T-RAN by a second UPF so as to forward the termination mark End Marker to the terminal through the T-RAN;

5. The method of claim 1, wherein when the terminal is in a CM-IDLE state, after controlling the second UPF to create an N9 tunnel from the second UPF to the first UPF, the method further comprises:

starting a third timer;

6. The method of claim 5, wherein the sending opportunity of the PFCP session report request includes:

7. The method of claim 6, wherein when the terminal is in a CM-IDLE state, a downlink data packet of the terminal is sent by a public network to the first UPF cache before the control of the first UPF update PFCP session; after the first UPF is controlled to update the PFCP session and before the first UPF is informed of sending a termination mark End Marker to a second UPF, forwarding a downlink data message sent to the first UPF cache by a public network to the second UPF cache through an N9 tunnel, and sending a new downlink data message to the first UPF by the public network to be sent to the second UPF cache by the first UPF; after notifying the first UPF to send a termination mark End Marker to a second UPF and before controlling the second UPF to update the PFCP session, forwarding a downlink data message sent by the first UPF to the second UPF cache to a T-RAN by the second UPF so as to be forwarded to the terminal by the T-RAN, and forwarding a new downlink data message to the second UPF cache by a public network; after the PFCP session report request sent by the second UPF is controlled to update the PFCP session, the public network forwards the data message buffered by the second UPF to the T-RAN from the second UPF so as to be forwarded to the terminal by the T-RAN, and the new downlink data message is forwarded to the second UPF from the public network so as to be forwarded to the T-RAN from the second UPF, so that the T-RAN forwards the data message to the terminal;

8. The method according to claim 1, characterized in that the method further comprises:

when the terminal is in a CM-CONNECTED state, if the position information of a base station accessed after the position change of the terminal, carried by a session update request sent by the AMF, is triggered before the position change of the terminal is not in the service range of a first UPF which currently provides service for the terminal and the first UPF is judged not to support UPF switching, a relay user plane function network element I-UPF is inserted to provide service for the terminal so that a downlink data message of the terminal is forwarded to the I-UPF by the first UPF, and the downlink data message is forwarded to the T-RAN by the I-UPF, so that the T-RAN forwards the downlink data message to the terminal; wherein, the terminal is in the service range of the I-UPF;

when the terminal is in a CM-IDLE state, triggering the position information of the terminal, carried by a session update request sent by the AMF, after the position change of the terminal is not in the service range of a first UPF which is used for providing service for the terminal currently and judging that the first UPF does not support UPF switching, inserting a relay user plane function network element I-UPF to provide service for the terminal so that a downlink data message of the terminal is forwarded to the I-UPF by the first UPF, and forwarding the downlink data message to the T-RAN by the I-UPF, so that the T-RAN forwards the downlink data message to the terminal; wherein the terminal is in the service range of the I-UPF.

9. A path switching device applied to a 5G core network, the device comprising:

the determining unit is used for enabling the SMF management terminal to be in a CONNECTED CM-CONNECTED state; when the terminal is in a CM-CONNECTED state, signaling connection is established between the terminal and an access and mobility management function network element AMF;

or,

the terminal for SMF management is in an IDLE CM-IDLE state; when the terminal is in a CM-IDLE state, no signaling connection is established between the terminal and the AMF;

A selecting unit, configured to select a second UPF to replace the first UPF to provide a service for the terminal if the terminal is in the CM-CONNECTED state and if the terminal is not in the CM-CONNECTED state and if the first UPF is determined to support UPF switching; the terminal is in the service range of the second UPF;

or,

when the terminal is in the CM-IDLE state, if not, and the first UPF is judged to support UPF switching, selecting a second UPF to replace the first UPF to provide service for the terminal; the terminal is in the service range of the second UPF;

the creation unit is used for controlling the second UPF to create a PFCP session with the SMF when the terminal is in the CM-CONNECTED state and prohibiting the second UPF from releasing the route information of the terminal;

or,

when the terminal is in a CM-IDLE state, the terminal is used for controlling the second UPF to create a PFCP session with the SMF and controlling the second UPF to release the routing information of the terminal;

10. The apparatus of claim 9, wherein the creating unit is further configured to, when the terminal is in the CM-CONNECTED state, after controlling the second UPF to create a first forwarding tunnel from the second UPF to the first UPF:

and/or, when the terminal is in the CM-CONNECTED state, after notifying the first UPF to delete the routing information of the terminal, the creating unit is further configured to:

starting a first timer and a second timer;

and/or, when the terminal is in the CM-IDLE state, after controlling the second UPF to create an N9 tunnel from the second UPF to the first UPF, the creating unit is further configured to:

starting a third timer;

and/or, the sending occasion of the PFCP session report request includes:

and/or the selection unit is further configured to:

11. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the method of any one of claims 1 to 8 when the program is executed by the processor.