CN109921918B

CN109921918B - Quality of service (QoS) control method and device

Info

Publication number: CN109921918B
Application number: CN201711316925.7A
Authority: CN
Inventors: 汪红星
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2017-12-12
Filing date: 2017-12-12
Publication date: 2020-10-23
Anticipated expiration: 2037-12-12
Also published as: CN109921918A

Abstract

The application discloses a QoS control method and device. The method comprises the following steps: the application function network element determines indication information and sends the indication information to the first strategy control network element, wherein the indication information comprises an identifier of a terminal and an identifier of a STUN server, and the indication information is used for indicating that an IP address of a PDU session of the terminal is inserted into a first response message sent to the terminal by the STUN server; thus, the first policy control network element receives the indication information and then sends the indication information to the second policy control network element, and the second policy control network element sends the indication information to the policy execution network element, and the policy execution network element can insert the IP address of the PDU session of the terminal into the first response message according to the indication information and send the IP address to the terminal; after the terminal obtains the IP address of the PDU session of the terminal, the terminal sends the IP address of the PDU session to the application function network element through the first message, so that the application function network element can obtain the IP address of the PDU session, and QoS control of the PDU session is realized.

Description

Quality of service (QoS) control method and device

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a QoS control method and apparatus.

Background

With the development of internet technology, NAT (Network Address Translation) technology is widely used. NAT is a conversion technique for converting an IP address of a private network (hereinafter, referred to as a private network IP address) into an IP address of a public network (hereinafter, referred to as a public network IP address). In practical applications, NAT is mainly used to implement the function of private network accessing public network. Through NAT, the user access network corresponding to more private IP addresses can be realized under the condition of using a small amount of public IP addresses. NAT not only perfectly solves the problem of insufficient lP address, but also can effectively avoid the attack from the outside of the network, and hide and protect the computer in the private network.

The basic working principle of the NAT is as follows: when a device on the private network side (hereinafter referred to as a private network side device, such as a terminal) and a device on the public network side (hereinafter referred to as a public network side device, such as an application function network element) communicate and pass through the NAT device, the NAT device converts a source IP address or a destination IP address in a message between a private network IP address and a public network IP address.

However, when the network has the NAT device, especially the user-side NAT device, the IP address of the terminal carried in the application layer signaling message of the terminal and the application function network element may be different from the IP address of the Protocol Data Unit (PDU) session of the terminal, and at this time, the application function network element may only know the IP address of the terminal but may not know the IP address of the PDU session of the terminal, and thus may not implement quality of service (QoS) control on the PDU session of the terminal.

In summary, there is a need for a QoS control method for solving the technical problem that QoS control cannot be performed on a PDU session of a terminal when NAT equipment exists.

Disclosure of Invention

The application provides a QoS control method, which is used for solving the technical problem that the QoS control of the PDU session of a terminal cannot be realized when NAT equipment exists.

In a first aspect, the present application provides a QoS control method, including:

an application function network element determines indication information, wherein the indication information comprises an identifier of the terminal and policy information, the policy information comprises an identifier of a STUN server, and the indication information is used for indicating that an IP address of a PDU session of the terminal is inserted into a first response message sent to the terminal by the STUN server;

and the application function network element sends the indication information to a first policy control network element.

Thus, the application function entity sends the indication information to the first policy control network element, and after receiving the indication information, the first policy control network element can send the indication information to the second policy control network element corresponding to the PDU session identifier of the terminal, and then the second policy control network element forwards the indication information to the policy execution network element; after monitoring a first response message sent to the terminal by the STUN server, the strategy execution network element inserts an IP address of a PDU session of the terminal into the first response message according to the indication information to obtain a second response message, and sends the second response message to the terminal; therefore, the terminal can obtain the IP address of the PDU session of the terminal from the second response message and further send the IP address to the application function network element through the first message, so that the application function network element can obtain the IP address of the PDU session and realize the QoS control of the PDU session; moreover, the method can be applied to various complex scenes (such as existence of a plurality of NAT devices), and has strong adaptability.

In one possible design, the policy information further includes a state, and the state is start or stop.

Thus, the policy information includes the start or stop state, so the application function network element can set different states according to different requirements.

In a possible design, if the state is start, after the applying function network element sends the indication information to the first policy control network element, the method further includes:

the application function network element receives a first message from a terminal, wherein the first message comprises an IP address of a PDU session of the terminal;

and the application function network element obtains the IP address of the PDU session of the terminal according to the first message and sends a QoS control request message to a second strategy control network element, wherein the QoS control request message comprises the IP address of the PDU session.

Further, the first message includes an IP address of the PDU session of the terminal, specifically, the SDP of the first message includes the IP address of the PDU session of the terminal.

Through the above manner, if the state in the policy information sent by the application function network element is start, it indicates that the policy is started, so that the subsequent application function network element can obtain the IP address of the PDU session of the terminal from the SDP of the first message sent by the terminal. In other embodiments, if the state in the policy information sent by the application function network element is stop, indicating that the policy is stopped, in this case, the application function network element may obtain the IP address of the PDU session of the terminal in a manner in the prior art.

In a second aspect, the present application provides a QoS control method, including:

the method comprises the steps that a first policy control network element receives indication information from an application function network element, wherein the indication information comprises an identifier of a terminal and policy information, the policy information comprises an identifier of a STUN server, and the indication information is used for indicating that an IP address of a PDU session of the terminal is inserted into a first response message sent to the terminal by the STUN server;

and the first policy control network element obtains the identifier of the PDU session of the terminal and a second policy control network element corresponding to the identifier of the PDU session of the terminal according to the identifier of the terminal, and sends the indication information to the second policy control network element corresponding to the identifier of the PDU session of the terminal.

In this application, the first policy control network element sends the indication information to the second policy control network element corresponding to the PDU session identifier of the terminal, and the corresponding second policy control network element may notify the policy enforcement network element to perform the session level operation according to the indication information.

In one possible design, the policy information further includes a status;

the sending, by the first policy control network element, the indication information to a second policy control network element corresponding to the identifier of the PDU session of the terminal includes:

the first strategy control network element obtains the record of the terminal according to the identifier of the terminal;

if the state is starting and the record of the terminal does not have the strategy subcontent corresponding to the strategy information, the first strategy control network element sends the indication information to a second strategy control network element corresponding to the PDU conversation identifier of the terminal; alternatively, the first and second electrodes may be,

and if the state is stop and the strategy subcontent corresponding to the strategy information exists in the record of the terminal, the first strategy control network element deletes the strategy subcontent corresponding to the strategy information from the record of the terminal and sends the indication information to a second strategy control network element corresponding to the PDU session identifier of the terminal.

In this way, the first policy control network element sends the indication information to the second policy control network element corresponding to the PDU session identifier of the terminal under the condition that the first policy control network element determines that the specific conditions are met according to the state in the policy information and the record of the terminal, thereby ensuring effective execution of the policy.

In a possible design, after the first policy control network element sends the indication information to a second policy control network element corresponding to an identifier of a PDU session of the terminal, the method further includes:

the first policy control network element receives a second notification message from a second policy control network element, wherein the second notification message comprises the identifier of the terminal and PDU session update information;

and the first strategy control network element obtains the record of the terminal according to the identifier of the terminal and updates the record of the terminal according to the PDU session update information.

In the application, the first policy control network element can update the record of the terminal in time after receiving the second notification message, so that the record of the terminal is ensured to be accurate and effective.

In one possible design, the PDU session update information includes an identification of a first PDU session and an update type of the first PDU session;

the first policy control network element updates the record of the terminal according to the PDU session update information, including:

if the update type of the first PDU session is newly increased, the first policy control network element adds a first PDU session sub-content in the record of the terminal, wherein the first PDU session sub-content comprises the identifier of the first PDU session and the identifier of the second policy control network element corresponding to the identifier of the first PDU session; alternatively, the first and second electrodes may be,

and if the update type of the first PDU session is deletion, the first policy control network element deletes second PDU session sub-content from the record of the terminal, wherein the second PDU session sub-content comprises the identification of the PDU session. Further, after the first policy control network element deletes the second PDU session sub-content, if it is determined that neither the PDU session sub-content nor the policy sub-content exists in the record of the terminal, the record of the terminal can be deleted, thereby saving the storage space.

By the above manner, the first policy control network element may perform different update operations according to different update types.

In one possible design, after the first policy control network element adds the first PDU session sub-content to the record of the terminal, the method further includes:

and the first policy control network element sends the indication information to the second policy control network element corresponding to the identifier of the first PDU session.

Therefore, under the condition of newly adding the PDU session, the first policy control network element can send the stored policy information to the second policy control network element corresponding to the newly added PDU session in time, that is, after the application function network element issues the policy information, the first policy control network element manages all PDU sessions (including the subsequent newly added PDU session) of the terminal according to the policy information.

In a third aspect, the present application provides a QoS control method, including:

the second strategy control network element receives indication information from the first strategy control network element, wherein the indication information comprises an identifier of a terminal and strategy information, the strategy information comprises an identifier of a STUN server, and the indication information is used for indicating that an IP address of a PDU session of the terminal is inserted into a first response message sent to the terminal by the STUN server;

and the second policy control network element sends the indication information to a policy execution network element.

Thus, after receiving the indication information, the second policy control network element may send the indication information to the corresponding policy enforcement network element, which is the policy enforcement network element that allocates the PDU session.

In one possible design, the method further includes:

a second strategy control network element receives a first notification message from the strategy execution network element, wherein the first notification message comprises the identification of the terminal and PDU session update information;

and the second policy control network element sends a second notification message to the first policy control network element according to the first notification message, wherein the second notification message comprises the identifier of the terminal and the PDU session update information.

In a fourth aspect, the present application provides a QoS control method, including:

the strategy execution network element receives indication information from a second strategy control network element, wherein the indication information comprises an identifier of a terminal and strategy information, and the strategy information comprises an identifier of a STUN server;

the strategy execution network element monitors a first response message sent to the terminal by the STUN server according to the identification of the STUN server, and inserts the IP address of the PDU session of the terminal into the first response message to obtain a second response message;

and the strategy execution network element sends the second response message to the terminal.

Therefore, after the policy enforcement network element receives the indication information, the IP address of the PDU session allocated by the policy enforcement network element for the terminal can be inserted into the first response message and sent to the terminal, so that the terminal can obtain the IP address of the PDU session.

In a fifth aspect, the present application provides a QoS control method, including:

the terminal sends a binding request message to the STUN server;

the terminal receives a second response message sent by a policy enforcement network element, wherein the second response message is obtained by the policy enforcement network element after inserting the IP address of the PDU session of the terminal into the received first response message returned by the STUN server;

and the terminal obtains the IP address of the PDU session of the terminal from the second response message and sends a first message to an application function network element, wherein the first message comprises the IP address of the PDU session of the terminal.

Therefore, the terminal obtains the IP address of the PDU session by sending the binding request message, and sends the IP address of the PDU session to the application function network element by the first message, so that the application function network element can realize the QoS control of the PDU session.

In one possible design, the first message is a call request message or a call response message.

In a sixth aspect, the present application provides an application function network element, where the application function network element includes:

a processing module, configured to determine indication information, where the indication information includes an identifier of the terminal and policy information, where the policy information includes an identifier of a STUN server, and the indication information is used to indicate that an IP address of a PDU session of the terminal is inserted in a first response message sent by the STUN server to the terminal;

and the transceiver module is used for sending the indication information to the first policy control network element.

In a possible design, if the status is start, after the transceiver module sends the indication information to the first policy control network element, the transceiver module is further configured to:

receiving a first message from a terminal, the first message including an IP address of a PDU session of the terminal;

and obtaining the IP address of the PDU session of the terminal according to the first message, and sending a QoS control request message to a second policy control network element, wherein the QoS control request message comprises the IP address of the PDU session.

In a seventh aspect, the present application provides a policy control network element, where the policy control network element includes:

a transceiver module, configured to receive indication information from an application function network element, where the indication information includes an identifier of a terminal and policy information, the policy information includes an identifier of a STUN server, and the indication information is used to indicate that an IP address of a PDU session of the terminal is inserted in a first reply message sent by the STUN server to the terminal;

the processing module is used for obtaining the PDU session identifier of the terminal and a second strategy control network element corresponding to the PDU session identifier of the terminal according to the terminal identifier;

the transceiver module is further configured to send the indication information to a second policy control network element corresponding to the PDU session identifier of the terminal.

In one possible design, the policy information further includes a status;

the processing module is specifically configured to:

obtaining a record of the terminal according to the identifier of the terminal;

if the state is starting and the strategy subcontent corresponding to the strategy information does not exist in the record of the terminal, the indication information is sent to a second strategy control network element corresponding to the PDU conversation identification of the terminal through the transceiver module; alternatively, the first and second electrodes may be,

and if the state is stop and the strategy subcontent corresponding to the strategy information exists in the record of the terminal, deleting the strategy subcontent corresponding to the strategy information from the record of the terminal, and sending the indication information to a second strategy control network element corresponding to the PDU conversation identifier of the terminal through the transceiver module.

In a possible design, after the transceiver module sends the indication information to a second policy control network element corresponding to an identifier of a PDU session of the terminal, the transceiver module is further configured to:

the processing module is further configured to: and obtaining the record of the terminal according to the identifier of the terminal, and updating the record of the terminal according to the PDU session updating information.

the processing module is specifically configured to:

if the update type of the first PDU session is newly added, adding a first PDU session sub-content in a record of the terminal, wherein the first PDU session sub-content comprises an identifier of the first PDU session and an identifier of the second policy control network element corresponding to the identifier of the first PDU session; alternatively, the first and second electrodes may be,

and if the update type of the first PDU session is deletion, deleting a second PDU session sub-content from the record of the terminal, wherein the second PDU session sub-content comprises the identification of the PDU session.

In one possible design, the transceiver module is further configured to:

and after the processing module adds the sub-content of the first PDU session in the record of the terminal, sending the indication information to the second policy control network element corresponding to the identifier of the first PDU session.

In an eighth aspect, the present application provides a policy control network element, where the policy control network element includes: the device comprises a processing module and a transmitting-receiving module;

the processing module receives indication information from a first policy control network element through the transceiver module, wherein the indication information comprises an identifier of a terminal and policy information, the policy information comprises an identifier of a STUN server, and the indication information is used for indicating that an IP address of a PDU session of the terminal is inserted into a first response message sent to the terminal by the STUN server; and sending the indication information to a policy enforcement network element.

In one possible design, the transceiver module is further configured to:

receiving a first notification message from the policy enforcement network element, wherein the first notification message comprises an identifier of a terminal and PDU session update information;

and sending a second notification message to a first policy control network element according to the first notification message, wherein the second notification message comprises the identifier of the terminal and the PDU session update information.

In a ninth aspect, the present application provides a policy enforcement network element, including:

a transceiver module, configured to receive indication information from a second policy control network element, where the indication information includes an identifier of a terminal and policy information, and the policy information includes an identifier of a STUN server;

the processing module is used for inserting the IP address of the PDU session of the terminal into the first response message to obtain a second response message after monitoring the first response message sent to the terminal by the STUN server according to the identification of the STUN server;

the transceiver module is further configured to send the second response message to the terminal.

In a tenth aspect, the present application provides a terminal, comprising:

the receiving and sending module is used for sending a binding request message to the STUN server; receiving a second response message sent by a policy enforcement network element, wherein the second response message is obtained by the policy enforcement network element after inserting the IP address of the PDU session of the terminal into the received first response message returned by the STUN server;

and the processing module is used for obtaining the IP address of the PDU session of the terminal from the second response message and sending a first message to an application function network element through the transceiver module, wherein the first message comprises the IP address of the PDU session of the terminal.

In an eleventh aspect, the present application provides a communication apparatus, which may be any one of an application function network element, a first policy control network element, a second policy control network element, a policy enforcement network element, and a terminal, and which has the function of implementing the method example of any one of the first to fifth aspects; the communication device includes: a communication module and a processor;

and the communication module is used for carrying out communication interaction with other equipment. The communication module may be an RF circuit, a Wi-Fi module, a communication interface, a bluetooth module, etc.

The processor is configured to implement the functions of the processing module in any one of the first aspect to the fifth aspect.

Optionally, the communication device may further include: the memory is used for storing programs and the like. In particular, the program may comprise program code comprising instructions. The memory may include Random Access Memory (RAM) and may also include non-volatile memory (non-volatile memory), such as at least one disk memory. The processor executes the application program stored in the memory to realize the functions.

In a possible manner, the communication module, the processor and the memory may be connected to each other by the bus; the bus may be a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The bus may be divided into an address bus, a data bus, a control bus, etc.

The present application further provides a communication system, where the system includes any one of the terminals provided by the above designs, and may further include a network device interacting with the terminal in the scheme provided by the present application, such as an application function network element, a first policy control network element, a second policy control network element, a policy enforcement network element, and the like.

The present application also provides a computer storage medium having stored therein a software program that, when read and executed by one or more processors, may implement the QoS control method provided by the above aspects or various possible designs.

The present application also provides a computer program product containing instructions which, when run on a computer, cause the computer to perform the QoS control method described in the aspects or various possible designs above.

The present application also provides a computer program which, when run on a computer, causes the computer to perform the QoS control method described in the above aspects or various possible designs.

Drawings

FIG. 1 is a schematic diagram of a network architecture suitable for use in the present application;

FIG. 2 is a schematic diagram of another network architecture suitable for use in the present application;

FIG. 3 is a schematic diagram of another network architecture suitable for use in the present application;

fig. 4 is a schematic flow chart of the NAT device in the present application;

fig. 5 is an interaction diagram of the STUN client and the STUN server in the present application;

fig. 6a is a flowchart illustrating a scenario according to an embodiment of the present application;

fig. 6b is a schematic flowchart corresponding to the scenario two provided in the embodiment of the present application;

fig. 7 is a flowchart illustrating a QoS control method according to an embodiment of the present application;

fig. 8 is a flowchart illustrating a QoS control method according to a second embodiment of the present application;

fig. 9 is a flowchart illustrating a QoS control method according to a third embodiment of the present application;

fig. 10 is a schematic structural diagram of a communication device according to an embodiment of the present application;

fig. 11 is a schematic structural diagram of another communication device according to an embodiment of the present application.

Detailed Description

The present application will now be described in detail with reference to the drawings, and the specific operations in the method embodiments may also be applied to the apparatus embodiments or the system embodiments. In the description of the present application, "a plurality" means two or more unless otherwise specified.

The network architecture and the service scenario described in the embodiment of the present application are for more clearly illustrating the technical solution of the embodiment of the present application, and do not form a limitation on the technical solution provided in the embodiment of the present application, and as a person of ordinary skill in the art knows that along with the evolution of the network architecture and the appearance of a new service scenario, the technical solution provided in the embodiment of the present application is also applicable to similar technical problems.

Fig. 1 is a schematic diagram of a network architecture to which the present application is applicable. As shown in fig. 1, the network architecture includes a terminal 101, an application function network element 102, a policy control network element 103, and a policy execution network element 104.

The terminal 101 is a device with a wireless transceiving function, and can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; can also be deployed on the water surface (such as a ship and the like); and may also be deployed in the air (e.g., airplanes, balloons, satellites, etc.). The terminal may be a User Equipment (UE), a mobile phone (mobile phone), a tablet (pad), a computer with wireless transceiving function, a Virtual Reality (VR) terminal, an Augmented Reality (AR) terminal, a wireless terminal in industrial control (industrial control), a wireless terminal in self driving (self driving), a wireless terminal in remote medical (remote medical), a wireless terminal in smart grid (smart grid), a wireless terminal in transportation safety, a wireless terminal in city (city), a wireless terminal in smart home (smart home), and so on.

And the application function network element 102 is configured to issue a QoS control request of a PDU session from the terminal to the policy enforcement network element 104 to the policy control network element 103 according to the service appeal.

The policy control network element 103 is configured to send a QoS control request of the PDU session from the application function network element 102 to the policy enforcement network element 104 that allocates and processes the PDU session.

The policy enforcement network element 104, which may also be referred to as a Policy and Charging Enforcement Function (PCEF) network element, is configured to perform QoS control on the PDU session according to a QoS control request from the policy control network element 103.

In the embodiment of the present application, in order to better cope with a complex NAT access scenario, a policy control network element may be divided into a first policy control network element and a second policy control network element, where the first policy control network element is used to control QoS of all PDU sessions of the terminal, and may also be referred to as a user-level policy control network element; the second policy control network element is configured to control QoS of the PDU session specified by the terminal, and may also be referred to as a session-level policy control network element. The user-level policy control network element or the session-level policy control network element may be a logical concept, and may be physically different entities (such as a case where a single UE supports multiple IPs), or may be unified entities (such as a case where a single UE supports a single IP).

The communication system to which the above network architecture is applicable includes but is not limited to: long Term Evolution (LTE) communication systems, as well as various wireless communication systems that evolve in the future, e.g., the fifth Generation (5th Generation, 5G) New Radio (NR) communication system.

When the network architecture is applied to an LTE communication system, the application function network element 102 may correspond to an Application Function (AF) network element, the policy control network element 103 may correspond to a Policy and Charging Rules Function (PCRF) network element, and the policy execution network element 104 may correspond to a packet data network gateway (PGW) network element. Based on this, referring to fig. 2, a schematic diagram of another network architecture applicable to the present application is shown, where the network architecture includes a terminal 201, a Radio Access Network (RAN) network element 202, a PGW network element 203, a PCRF network element 204, and an AF network element 205.

For a description of the terminal 201, reference may be made to the content of the terminal 101 in fig. 1, and details are not described here.

A RAN network element 202 configured to provide network resources for the terminal. The RAN network element 202 may be a base station in an LTE communication system, and may also be referred to as an eNodeB or an eNB, and is responsible for radio resource management, uplink and downlink data classification and quality of service (QoS) application, and performs signaling processing and data forwarding functions together with other related network elements.

The PGW network element 203 is configured to perform functions such as PDU session management, execution of control policy issued by the PCRF, IP address allocation of the PDU session, and complete functions such as user plane data forwarding, QoS based on PDU session/flow level, charging statistics, and bandwidth limitation.

And the PCRF network element 204 is configured to perform policy control on QoS, charging, mobility, and the like for the PDU session and the service flow level. Further, the PCRF network element 204 may include a first PCRF network element and a second PCRF network element; the first PCRF network element corresponds to a first policy control network element and is used for controlling the QoS of all PDU sessions of the terminal; and the second PCRF network element corresponds to a second policy control network element and is used for controlling the QoS of the PDU session specified by the terminal.

The AF network element 205 is configured to provide an application service (also referred to AS a service) to a user, and functions AS a service capability server/application server (SCS/AS), but only names of the service capability server/application server and the SCS/AS are different. In this application, the AF network element may be an application server deployed by an operator, or may be an application server deployed by a third party.

When the network architecture is applied to a 5G NR communication system, the application function network element 102 may correspond to an AF network element, the policy control network element 103 may correspond to a Policy Control Function (PCF) network element, and the policy execution network element 104 may correspond to a User Plane Function (UPF) network element or a Session Management Function (SMF) network element. Based on this, referring to fig. 3, a schematic diagram of another network architecture applicable to the present application is shown, where the network architecture includes a terminal 301, (R) AN network element 302, a UPF network element 303, AN SMF network element 304, a PCF network element 305, and AN AF network element 306.

The description of the terminal 301 may refer to the content of the terminal 101 in fig. 1, and the description of the AF network element 306 may refer to the content of the AF network element 205 in fig. 2, which are not described herein again.

(R) AN network element 302 for providing network resources for the terminal. The (R) AN network element 302 may be a base station in a 5G NR communication system, and is responsible for radio resource management, uplink and downlink data classification and QoS application, and completes signaling processing together with a control plane network element, and completes data forwarding together with a UPF network element.

And the UPF network element 303 is used for routing and forwarding packets, and performing QoS processing on user plane data.

The SMF network element 304 mainly has functions including session management, terminal Internet Protocol (IP) address allocation and management, selection and management of a user plane functional network element, a terminal of a policy control and charging functional interface, downlink data notification, and the like. The session management function may include a session management function of a mobility management element MME, or include a control plane function of a Serving Gateway (SGW) and a public data network (PDN-GW) in LTE.

The PCF network element 305 has a main Function of performing Policy control, and is similar to a Policy and Charging Rules Function (PCRF) network element in LTE, and is mainly responsible for Policy authorization, generation of service quality and Charging Rules, and issuing corresponding Rules to a UPF network element through an SMF network element, thereby completing installation of corresponding policies and Rules. Further, PCF network element 305 may include a first PCF network element and a second PCF network element; the first PCF network element corresponds to a first policy control network element and is used for controlling the QoS of all PDU sessions of the terminal; and the second PCF network element corresponds to a second policy control network element and is used for controlling the QoS of the PDU session specified by the terminal.

According to the above contents, the network architecture for QoS control in the 5G NR communication system is similar to the network architecture for QoS control in the LTE communication system, and the PCF network element corresponds to the PCRF network element, and the functions of the PCF network element and the PCRF network element are the same; the SMF network element and the UPF network element jointly complete the function of the PCEF network element, the SMF network element is responsible for the distribution/release management of the PDU session, and the UPF network element is responsible for actually processing the message of the PDU session. The Rx interface corresponds to the N5 interface and the Gx interface corresponds to the N7 interface.

It should be noted that: (1) the network elements to which the present application relates are only illustrated in fig. 2 and 3 for simplicity, and in other embodiments other network elements may be present. (2) In this application, the network element may be a physical entity network element or a virtual network element, which is not limited herein.

Taking the network architecture illustrated in fig. 2 as an example, when there is no NAT device, the IP address of the terminal is carried in the Session Description Protocol (SDP) of the application layer messages of the terminal and the AF network element, and the IP address of the terminal is consistent with the IP address of the PDU session, and at this time, the AF network element may directly use the IP address carried in the application layer message to be issued to the PCRF network element through the Rx interface to complete QoS control of the PDU session.

When there are NAT devices, as shown in fig. 4, two NAT devices (a first NAT device 206a and a second NAT device 206b) are taken as an example, where the first NAT device may be referred to as a user-side NAT device, and the second NAT device may be referred to as a network-side NAT device. The specific process can be as follows: the PGW network element is responsible for allocating a network side IP address (IP2) to the first NAT device, and the first NAT device is responsible for allocating an IP address (IP1) to the terminal; the source IP address of the network layer in the message sent by the terminal to the AF network element is IP1, and the IP address carried by the SDP of the application layer message is IP 1; when the message passes through the first NAT equipment, the first NAT equipment modifies the source IP of the message network layer into IP 2; when the message reaches the second NAT device, the second NAT device modifies the source IP address of the message network layer into IP3, therefore, when the message reaches the AF network element, the AF network element can only obtain the IP1/IP3 address from the message. However, the IP address of the PDU session known by the PCRF network element is IP2, and what the AF network element should carry when issuing the QoS control request to the PCRF is IP2, but the AF network element cannot obtain IP2, so that the QoS control of the PDU session of the terminal cannot be implemented.

Based on this, the embodiment of the present application provides a QoS control method, which is used to solve the technical problem that QoS control cannot be performed on a PDU session of a terminal when NAT equipment exists.

Specifically, the application function network element determines indication information and sends the indication information to a first policy control network element; the indication information comprises an identifier of the terminal and policy information, the policy information comprises an identifier of a STUN server, and the indication information is used for indicating that an IP address of a PDU session of the terminal is inserted into a first response message sent to the terminal by the STUN server; thus, after receiving the indication information, the first policy control network element sends the indication information to a second policy control network element corresponding to the PDU session identifier of the terminal, and the second policy control network element forwards the indication information to the policy execution network element; after monitoring a first response message sent to the terminal by the STUN server, the strategy execution network element inserts an IP address of a PDU session of the terminal into the first response message according to the indication information to obtain a second response message, and sends the second response message to the terminal; therefore, the terminal can obtain the IP address of the PDU session of the terminal from the second response message and further send the IP address to the application function network element through the first message, so that the application function network element can obtain the IP address of the PDU session and realize the QoS control of the PDU session; moreover, the method can be applied to various complex scenes (such as existence of a plurality of NAT devices), and has strong adaptability.

Among them, STUN (simple traversal of UDP over NATs) is a network protocol used for discovering public network addresses and ports of devices (such as terminals) after NAT or multiple NATs. As shown in fig. 5, a STUN client (client) side (e.g., a terminal) sends a binding request message to a STUN server (server) side (e.g., a STUN server) for detecting a public network address and a port after NAT; after receiving the binding request message, the STUN server sends a binding response message to the terminal, and carries the public network ADDRESS and the port of the terminal after NAT through the XOR-MAPPED-ADDRESS parameter in the binding response message.

Before specifically describing the QoS control method in the embodiment of the present application, a relationship between a first policy control network element and a second policy control network element is further described with reference to two scenarios.

Scene one

Step 6011, the policy enforcement network element sends a first notification message to a second policy control network element, where the first notification message includes an identifier of the terminal and PDU session update information.

Here, the policy enforcement network element may send the first notification message to the corresponding second policy control network element over an interface (e.g., Gx interface).

The PDU session update information includes an identification of a first PDU session and an update type of the first PDU session. The update type of the first PDU session may be new (at this time, the policy enforcement network element allocates a new first PDU session to the terminal) or deleted (at this time, the policy enforcement network element releases the first PDU session of the terminal).

In this application, the identifier of the terminal may be information for uniquely identifying the terminal, such as an IMSI or an MS-ISDN number of the terminal, and the identifier of the PDU session may be information for uniquely identifying the PDU session, such as an IP address of the PDU session.

Step 6012, the second policy control network element receives the first notification message from the policy enforcement network element.

Here, after receiving the first notification message, the second policy control network element obtains the identifier of the first PDU session and the update type of the first PDU session from the first notification message.

Step 6013, the second policy control network element sends a second notification message to the first policy control network element, where the second notification message includes the identifier of the terminal and the PDU session update information.

Step 6014, the first policy control network element receives the second notification message sent by the second policy control network element.

Here, after receiving the second notification message, the first policy control network element obtains the identifier of the first PDU session and the update type of the first PDU session from the second notification message.

Step 6015, the first policy control network element obtains the record of the terminal according to the identifier of the terminal, and updates the record of the terminal according to the PDU session update information.

Specifically, for the situation of newly establishing a PDU session (the update type of the first PDU session is newly added), the first policy control network element searches the record of the terminal according to the identifier of the terminal, and if the record of the terminal is found, directly adding the first PDU session sub-content to the record of the terminal; and if the record of the terminal cannot be searched, newly adding the record of the terminal, and adding the first PDU session sub-content in the record of the terminal. The first PDU session sub-content includes the identifier of the first PDU session and the identifier of the second policy control network element corresponding to the identifier of the first PDU session.

In this case, the method further includes: step 6016, if the first policy control network element determines that policy information of the terminal exists (for example, the policy information is received and stored from an application function network element before updating the sub-content of the first PDU session), the first policy control network element sends the identifier of the terminal and the policy information to the second policy control network element corresponding to the identifier of the first PDU session.

Step 6017, after receiving the identifier of the terminal and the policy information from the first policy control network element, the second policy control network element forwards the identifier of the terminal and the policy information to the policy enforcement network element (i.e., the policy enforcement network element that allocates the first PDU session), and notifies the policy enforcement network element to perform a corresponding operation.

And aiming at the situation of releasing the PDU session (the update type of the first PDU session is deletion), the first strategy control network element searches the record of the terminal according to the identifier of the terminal and deletes the sub-content of the second PDU session from the record of the terminal, wherein the sub-content of the second PDU session comprises the identifier of the PDU session. Further, after deleting the second PDU session sub-content, if it is determined that there is no PDU session sub-content or no policy sub-content in the record of the terminal, the first policy control network element may delete the record of the terminal.

The above scenario a specifically describes an interaction flow between a first policy control network element and a second policy control network element triggered after a policy enforcement network element updates a PDU session.

Scene two

Step 6021, the application function network element sends the indication information to the first policy control network element.

Here, the indication information includes an identification of the terminal and policy information, which may be a variety of information. In this embodiment of the present application, the policy information may include an identifier and a status of the STUN server (which is specifically described in the following embodiments), where when the status is start, the indication information is used to indicate that an IP address of a PDU session of the terminal is inserted in a first reply message sent by the STUN server to the terminal; and when the state is stop, the indication information is used for indicating to stop inserting the IP address of the PDU session of the terminal in the first response message.

Step 6022, the first policy control network element receives the indication information from the application function network element.

Specifically, after the first policy control network element receives the indication information, if the state of the policy information is start, the first policy control network element checks whether the policy sub-content corresponding to the policy information exists in the record of the terminal, if the policy sub-content exists and is the same as the policy sub-content, the first policy control network element ignores the policy sub-content, and if the policy sub-content does not exist or is different from the policy sub-content, a new policy sub-content is added, the policy information is stored, and the new policy sub-content is recorded in the user-level policy difference table, and the state.

And if the state of the policy information is stop, whether the policy sub-content corresponding to the policy information exists in the record of the first policy control network element terminal, if not, ignoring the policy sub-content, if so, deleting the policy sub-content, recording the deleted policy sub-content into a user-level policy difference table, and setting the state to be stop. Further, after deleting the policy sub-content, if it is determined that the PDU session sub-content and the policy sub-content do not exist in the record of the terminal, the first policy control network element may delete the record of the terminal.

Step 6023, the first policy control network element obtains the identification of the PDU session of the terminal and the second policy control network element corresponding to the identification of the PDU session of the terminal according to the identification of the terminal, and sends the indication information to the second policy control network element corresponding to the identification of the PDU session of the terminal.

Specifically, when a first policy control network element finds that a record exists in a user-level policy difference table and the record of the terminal includes PDU session sub-content, request messages are sent to a second policy control network element corresponding to the PDU session identifier one by one, and the request messages carry information (namely, indicating information) recorded in the user-level policy difference table.

Step 6024, the second policy control network element receives the indication information from the first policy control network element.

Step 6025, the second policy control network element sends the indication information to the policy execution network element, so that the policy execution network element executes corresponding operation according to the policy information.

The second scenario specifically describes an interaction flow between the first policy control network element and the second policy control network element, which is triggered after the application function network element issues the indication information.

The QoS control method is described below with reference to specific embodiments.

Example one

Fig. 7 is a flowchart illustrating a QoS control method according to an embodiment of the present application, where as shown in fig. 7, the method includes:

step 701, the application function network element determines the indication information.

Here, the indication information includes an identity of the terminal and policy information including an identity of a STUN server.

Specifically, the policy information may include an identifier of a STUN server, or may also include identifiers of multiple STUN servers, and when the policy information includes identifiers of multiple STUN servers, reliability can be effectively improved. Further, the one or more STUN servers are available STUN servers of the terminal after all NATs, and the identifier of the one or more STUN servers may be obtained by the application function network element in a variety of ways, for example, by means of configuration or by means of active registration of the STUN server with the application function network element, which is not limited specifically.

The identification of the STUN server may include an IP address, a port of the STUN server, and optionally a connection protocol type, wherein the connection protocol type may support UDP and TDP. In other embodiments, the identity of the STUN server may also include other content, which is not limited in this application. In one example, the identification of the STUN server includes the STUN server's IP address, port, and connection protocol type.

In the following, taking the policy information including the identities of n STUN servers as an example, where n is an integer greater than or equal to 1, see table 1, which is an illustration of the content included in the policy information.

Table 1: content schematics included with policy information

STUN server	IP address	Port(s)	Connection protocol type
				STUN server 1	***	***	UDP
STUN server 2	***	***	TDP
				……	……	……	……
STUN server n	***	***	TDP

It should be noted that: table 1 is only an exemplary representation, and in a specific implementation, additions and deletions may be performed on the basis of table 1 according to actual needs, which is not limited in this application.

Further, the policy information may further include a state, where the state may be start or stop; when the state is starting, indicating that the IP address of the PDU session of the terminal is inserted into a first response message sent to the terminal by the STUN server; and when the state is stop, indicating to stop inserting the IP address of the PDU session of the terminal in the first response message. The following process is described by taking the state as the starting example.

In the application, the application function network element may check whether the NAT device exists after receiving the registration request message of the terminal and determining that the terminal is successfully registered, and if so, determine the indication information and execute the subsequent process, and if not, may directly adopt the existing QoS control method.

Step 702, the application function network element sends the indication information to the first policy control network element.

Here, in a possible implementation manner, the application function network element may insert an indication parameter in a policy request message that is sent to the first policy control network element corresponding to the terminal, and the content of the indication parameter may include the policy information.

Considering that the policy request message is sent through an interface between the application function network element and the first policy control network element, an Attribute Value Pair (AVP) type indicating that a parameter needs to extend the interface is inserted into the policy request message. The name of the new AVP type after the insertion of the indication parameter is: Insert-PDN, see table 2, is an exemplary format for the new AVP type.

Table 2: an exemplary format for a new AVP type

It should be noted that, in a normal situation, since a service can be initiated at any time, the application function network element does not need to issue a policy request message for stopping the IP address for inserting the PDU session in the first response message to the first policy control network element. Of course, the application function network element may also issue a policy request message for stopping the IP address of the PDU session inserted in the first response message to the first policy control network element when the terminal logs off according to the local configuration, and at this time, the policy request message may carry an indication parameter whose state is set to stop.

It should be noted that, the above-mentioned insertion of the indication parameter in the policy request message is only an example. In the LTE communication system, the application function network element may also insert an indication parameter in an Authentication Authorization Request (AAR) message, which is not described herein again.

In step 703, the first policy control network element receives indication information from the application function network element.

Step 704, the first policy control network element obtains, according to the identifier of the terminal, the identifier of the PDU session of the terminal and the second policy control network element corresponding to the identifier of the PDU session of the terminal, and sends the indication information to the second policy control network element corresponding to the identifier of the PDU session of the terminal.

According to the content of the scenario one, the first policy control network element may obtain, by querying a record of the terminal, an identifier of the PDU session of the terminal and a second policy control network element corresponding to the identifier of the PDU session of the terminal.

Further, after the first policy control network element sends the indication information to a second policy control network element corresponding to the PDU session identifier of the terminal, the method further includes: the first strategy control network element receives a second notification message from a second strategy control network element, wherein the second notification message comprises the identification of the terminal and PDU session update information; and the first strategy control network element obtains the record of the terminal according to the identifier of the terminal and updates the record of the terminal according to the PDU session update information. Specifically, if the update type of the first PDU session is newly added, the first policy control network element adds a first PDU session sub-content in the record of the terminal, where the first PDU session sub-content includes an identifier of the first PDU session and an identifier of the second policy control network element corresponding to the identifier of the first PDU session; and the first policy control network element sends the indication information to the second policy control network element corresponding to the identifier of the first PDU session. If the update type of the first PDU session is deletion, the first policy control network element deletes second PDU session subcontent from the record of the terminal, wherein the second PDU session subcontent comprises the identification of the PDU session; and if the first policy control network element determines that the record of the terminal is empty, deleting the record of the terminal.

For example, the first policy control network element queries a record of the terminal according to the identifier of the terminal, and the record of the terminal includes: and the PDU session 1 and a second strategy control network element a corresponding to the PDU session 1, and the PDU session 2 and a second strategy control network element b corresponding to the PDU session 2. In this way, the first policy control network element sends the indication information to the second policy control network element 1 and the second policy control network element b, respectively. If the second notification message received by the first policy control network element is added with PDU session 3 and a second policy control network element c corresponding to PDU session 3 in the record of the terminal according to the second notification message, at this time, the first policy control network element may send indication information to the second policy control network element c.

That is to say, in this embodiment of the present application, after receiving the indication information, the first policy control network element may first send the indication information to the second policy control network element corresponding to the identifier of the existing PDU session of the terminal, and may also send the indication information to the second policy control network element corresponding to the identifier of the newly added PDU session after the subsequent terminal has the newly added PDU session, thereby implementing control over all PDU sessions of the terminal.

In step 705, the second policy control network element receives indication information from the first policy control network element.

Step 706, the second policy control network element sends the indication information to the policy enforcement network element.

Further, after the second policy control network element sends the indication information to the policy enforcement network element, a first response message may be returned to the first policy control network element; correspondingly, after receiving the first response message, the first policy control network element may return a second response message to the application function network element; correspondingly, after receiving the second response message, the application function network element sends the identity of the STUN server (which is the same as the identity of the STUN server in the indication information) to the terminal. Specifically, the application function network element may send the identifier of the STUN server to the terminal through registering a corresponding message, or may send other messages, which is not limited specifically. And the terminal receives the identification of the STUN server from the application function network element and stores the identification.

In step 707, the policy enforcement network element receives indication information from the second policy control network element.

Here, after receiving the indication information, the policy enforcement network element obtains an identifier of the terminal and an identifier of the STUN server, and monitors a first response message sent by the STUN server to the terminal. The specific monitoring method may be that after receiving any message sent by any STUN server, the policy enforcement network element may determine whether the identity of the STUN server is consistent with the identity of the STUN server in the indication information, such as whether the IP address is consistent, whether the port is consistent, and whether the connection protocol type is consistent, and if it is determined that the identity of the STUN server is consistent with the identity of the STUN server in the indication information, further determine whether the message is a first response message sent to the terminal, and if so, may determine to monitor the first response message sent by the STUN server to the terminal.

In step 708, the terminal sends a binding request message to the STUN server.

Here, in the calling flow, before the terminal initiates a call, after allocating the local IP address and port of the media stream, and finding that the identity of the STUN server is stored, the local IP address and port of the media stream may be used as the source IP address and port, and a binding request message may be sent to the STUN server.

In the called flow, the terminal receives the call request message, before answering the call request message, allocates the local IP address and port of the media stream, finds that the identification of the STUN server is stored, and then can take the local IP address and port of the media stream as the source IP address and port, and sends the binding request message to the STUN server.

It should be noted that: (1) if the terminal stores the identities of a plurality of STUN servers, when sending the binding request message, the terminal may select one of the STUN servers and send the binding request message to the selected STUN server, and the specific selection manner may be various, such as random selection, which is not limited in this application. (2) The calling process and the called process are only descriptions of two possible scenarios, and this is not specifically limited in this application.

In step 709, the STUN server returns a first response message to the terminal.

Here, the public network address and the port of the terminal detected by the STUN server are included in the first reply message.

In particular, the STUN server sends a first reply message to the policy enforcement network element for forwarding by the policy enforcement network element to the terminal.

Step 710, after monitoring the first response message sent to the terminal by the STUN server according to the identification of the STUN server, the policy enforcement network element inserts the IP address of the PDU session of the terminal into the first response message to obtain a second response message.

In a possible implementation manner, the policy enforcement network element may insert a PDN-IP-ADDRESS field after the MESSAGE INTEGRITY field MESSAGE-INTEGRITY of the first reply MESSAGE, where the PDN-IP-ADDRESS field records an IP ADDRESS of a PDU session of the terminal. In this way, the PDN-IP-ADDRESS field is added on the basis of the message integrity field, and the message integrity field of the first response message is not changed, so that the terminal can correctly parse the second response message.

Step 711, the policy enforcement network element sends the second response message to the terminal.

Here, the terminal may obtain an IP address of the PDU session from the received second reply message.

Further, in step 708, the terminal may be assigned multiple media streams, such as media stream 1, media stream 2.

If the terminal has a plurality of PDU sessions, such as PDU session 1 and PDU session 2, the terminal can take the local IP address and port of the media stream 1 as the source IP address and port, and send a binding request message 1 to the STUN server through the PDU session 1, so as to obtain the IP address of the PDU session 1; and the local IP address and the port of the media stream 2 can be used as a source IP address and a port, and the binding request message is sent to the STUN server through the PDU session 2, so that the IP address of the PDU session 2 can be obtained. In this case, media flow 1 and media flow 2 are transmitted through different PDU sessions, which have different IP addresses, and thus, the PDN-IP-addresses of media flow 1 and media flow 2 are different.

If the terminal only has one PDU session, for example, PDU session 3, the terminal can take the local IP address and port of media stream 1 as the source IP address and port, and send binding request message 1 to the STUN server through PDU session 3, and then can obtain the IP address of PDU session 3; and sending a binding request message to the STUN server through the PDU session 3 by taking the local IP address and the port of the media stream 2 as a source IP address and a port, and further obtaining the IP address of the PDU session 3. In this case, media stream 1 and media stream 2 are transmitted through the same PDU session, and thus, the PDN-IP-addresses of media stream 1 and media stream 2 are the same.

Step 712, the terminal obtains the IP address of the PDU session of the terminal from the second response message, and sends a first message to an application function network element, where the first message includes the IP address of the PDU session of the terminal.

Here, in the caller flow, the first message may be a call request message; in the called flow, the first message may be a call response message; in other scenarios, the first message may also be other messages, and is not limited specifically.

In this application, the first message carries the IP address of the PDU session, which may specifically refer to that the SDP of the first message carries the IP address of the PDU session of the terminal.

Further, if the PDN-IP-addresses of the multiple media streams are different, the extended PDN-IP-ADDRESS information may be carried at the media level (per m rows) in the SDP, and if the PDN-IP-addresses of the multiple media streams are all the same, the extended PDN-IP-ADDRESS information is carried only at the session level.

In the present application, the format expansion effect of the PDN-IP-ADDRESS is as follows: the method comprises the steps of a, PDN-IP-ADDRESS, wherein < ADDRESS type > < connection ADDRESS >, wherein the < ADDRESS type > is used for describing an IP ADDRESS type, values comprise IPV4 and IPV6, the < connection ADDRESS > is used for describing a specific IP ADDRESS, the specific IP ADDRESS can be an IPV4 ADDRESS or an IPV6 ADDRESS, and a corresponding description character string is IP4 or IP 6. The effects are exemplified as follows: IP410.110.1.100 PDN-IP-ADDRESS

Example 1, the session level carries the PDN-IP-ADDRESS parameter as follows:

v＝0

o＝-1609961569 1609961569IN IP4 200.196.117.140

c＝IN IP4 200.196.117.140

IP410.110.1.100// this is the session level PDN-IP-ADDRESS, before all m-xxx rows

t＝0 0

m＝audio 15010 RTP/AVP 18

a＝rtpmap:18 G729/8000

m＝video 0 RTP/AVP 34

a＝rtpmap:34H263/90000

In this case, the first message carries the IP address of a PDU session, such as 10.110.1.100.

Example 2, the media level carries the PDN-IP-ADDRESS parameter as follows:

v＝0

o＝-1609961569 1609961569 IN IP4 200.196.117.140

c＝IN IP4 200.196.117.140

t＝0 0

m＝audio 15010 RTP/AVP 18

a＝rtpmap:18 G729/8000

IP410.110.1.99// this is the media level PDN-IP-ADDRESS, in the m-xxx row

m＝video 0 RTP/AVP 34

a＝rtpmap:34 H263/90000

IP410.110.1.100// this is the media level PDN-IP-ADDRESS, in the m-xxx row

In this case, the first message carries the IP addresses of multiple PDU sessions, such as 10.110.1.99 and 10.110.1.100.

In step 713, the application function network element receives the first message from the terminal.

Step 714, the application function network element obtains the IP address of the PDU session of the terminal according to the first message, and sends a QoS control request message to a second policy control network element, where the QoS control request message includes the IP address of the PDU session.

Specifically, when the application function network element sends the QoS control request message to the policy control network element, the IP Address field Framed-IP-Address or Framed-IPv6-Prefix value of the terminal of the Rx or N5 interface may be replaced with the content of the PDN-IP-Address (IP Address of the PDU session), and thus, the QoS control request message includes the IP Address of the PDU session.

Further, if the first message carries IP addresses of multiple PDU sessions, the application function network element may send a QoS control request message to a corresponding second policy control network element for the IP addresses of different PDU sessions, respectively.

For example, the first message carries the IP address of PDU session 1 and the IP address of PDU session 2; for the PDU session 1, the application function network element may replace the value of the IP Address field Framed-IP-Address or Framed-IPv6-Prefix of the terminal of the Rx or N5 interface with the content of the PDN-IP-Address (IP Address of the PDU session 1) and send the result to the second policy control network element corresponding to the PDU session 1. For PDU session 2, the application function network element may replace the value of the IP Address field Framed-IP-Address or Framed-IPv6-Prefix of the terminal of the Rx or N5 interface with the content of the PDN-IP-Address (IP Address of PDU session 2) and send the result to the second policy control network element corresponding to PDU session 2.

And 715, the second policy control network element performs QoS control on the PDU session according to the IP address of the PDU session. The specific implementation can refer to the prior art, and is not described herein in detail.

It should be noted that: (1) the step number is only an example of an execution flow, and the execution sequence of each step in this embodiment is not specifically limited.

(2) The above steps 701 to 707 are used to prepare for the following steps 708 to 715, that is, steps 701 to 707 are preparation stages, and steps 708 to 715 are implementation stages. After steps 701 to 707 are executed, step 708 to step 715 may be executed repeatedly, for example, in a calling scenario, the terminal initiates a call for multiple times, and then step 708 to step 715 are triggered for multiple times.

Through the process, the application function network element can obtain the IP address of the PDU session, and the QoS control of the PDU session is realized; moreover, the method can be applied to various complex scenes (such as existence of a plurality of NAT devices), and has strong adaptability.

Based on the description in the first embodiment, the following describes specific flows of the method in the embodiment of the present application in the LTE communication system (embodiment two) and the 5G NR communication system (embodiment three), respectively.

Example two

Fig. 8 is a flowchart illustrating a QoS control method according to a second embodiment of the present application. In fig. 8, the PCRF network element of the LTE communication system includes a first PCRF network element and a second PCRF network element, where the first PCRF network element corresponds to a first policy control network element and is used to control the QoS of all PDU sessions of the terminal; and the second PCRF network element corresponds to a second policy control network element and is used for controlling the QoS of the PDU session specified by the terminal.

As shown in fig. 8, includes:

in step 800, the terminal sends a registration request message to an AF network element.

Step 801, after the terminal is successfully registered, the AF network element sends indication information to the first PCRF network element, where the indication information includes an identifier of the terminal and policy information, and the policy information includes an identifier of the STUN server.

Here, the AF network element may send the indication information through an AAR request message.

Further, the policy information may further include a state, where the state may be start or stop, and when the state is start, the indication information is used to indicate that the IP address of the PDU session of the terminal is inserted in the first reply message sent by the STUN server to the terminal, and when the state is stop, the indication information is used to indicate that the IP address of the PDU session of the terminal is inserted in the first reply message sent by the STUN server to the terminal is stopped.

Step 802, after receiving the indication information, the first PCRF network element obtains, according to the identifier of the terminal, the identifier of the PDU session of the terminal and the second PCRF network element corresponding to the identifier of the PDU session of the terminal, and sends the indication information to the second PCRF network element corresponding to the identifier of the PDU session of the terminal.

Here, as can be known from the procedure of distributing the PDU session in the first scenario, the first PCRF network element stores the identifier of the PDU session of the terminal and the identifier of the second PCRF network element corresponding to the identifier of the PDU session of the terminal, and therefore, the first PCRF network element can determine the second PCRF network element corresponding to the identifier of the PDU session of the terminal and send the indication information to the determined second PCRF network element.

For example, a first PCRF network element obtains a record of a terminal according to an identifier of the terminal, where the record of the terminal includes two PDU session sub-contents, where the PDU session sub-content 1 includes a second PCRF network element 1 corresponding to the PDU session 1 and the PDU session 1, and the PDU session sub-content 2 includes a second PCRF network element 2 corresponding to the PDU session 2 and the PDU session 2. Thus, the first PCRF network element may send the indication information to the second PCRF network element 1 and the second PCRF network element 2, respectively.

Further, the first PCRF network element stores the indication information, and if the subsequent first PCRF network element determines that the terminal has a newly added PDU session (for example, PDU session 3), the first PCRF network element may send the indication information to the second PCRF network element 3.

Step 803, after receiving the indication information sent by the first PCRF network element, the second PCRF network element sends the indication information to the PGW network element, where the PGW network element is the PGW network element that allocates the PDU session.

Here, the second PCRF network element may be any one of the second PCRF network element 1, the second PCRF network element 2, and the second PCRF network element 3 in the above example.

Step 804, the PGW network element receives the indication information, and returns a successful response to the second PCRF network element.

Step 805, the second PCRF network element returns the first response message to the first PCRF network element.

Step 806, after receiving the first response message, the first PCRF network element returns a second response message to the AF network element.

In step 807, after receiving the second response message returned by the first PCRF network element, the AF network element returns a registration response message to the terminal, where the registration response message includes the identifier of the STUN server, that is, the identifier is the same as the identifier of the STUN server included in the indication information.

In step 808, the terminal sends a binding request message to the STUN server.

Step 809, after receiving the binding request message of the terminal, the STUN server returns a first response message to the terminal.

Step 810, the PGW network element monitors a first response message sent by the STUN server, and inserts an IP address of the PDU session allocated for the terminal into the first response message to obtain a second response message.

Step 811, the PGW network element sends the second response message to the terminal.

In step 812, the terminal receives the second response message.

Step 813, the terminal sends a first message to an AF network element, where the first message carries the IP address of the PDU session.

Step 814, after receiving the first message, the AF network element obtains the IP address of the PDU session from the first message, and sends a QoS control request message to a second PCRF network element, where the QoS control request message includes the IP address of the PDU session.

Step 815, the second PCRF network element performs QoS control on the PDU session according to the IP address of the PDU session.

(2) In a specific implementation, some steps described in the above procedure are not necessary, for example, the application function network element may also send the indication information to the first PCRF network element under the trigger of other factors, in this case, step 800 may not be included, and in step 801, the AF network element does not need to use the successful terminal registration as a precondition for sending the indication information to the first PCRF network element, and specifically, the above steps may be appropriately added or deleted according to an actual situation or an actual need; alternatively, some steps may be performed using other alternatives, which are not limited in this application.

EXAMPLE III

Fig. 9 is a flowchart illustrating a QoS control method according to a third embodiment of the present application. In fig. 9, the PCF network element of the 5GNR communication system includes a first PCF network element and a second PCF network element, where the first PCF network element corresponds to a first policy control network element and is used to control QoS of all PDU sessions of the terminal; and the second PCF network element corresponds to a second policy control network element and is used for controlling the QoS of the PDU session specified by the terminal.

As shown in fig. 9, includes:

in step 900, the terminal sends a registration request message to the AF network element.

Step 901, after the terminal is successfully registered, the AF network element sends indication information to the first PCF network element, where the indication information includes an identifier of the terminal and policy information, and the policy information includes an identifier of the STUN server.

Here, the AF network element may send the indication information through a policy request message.

Step 902, after receiving the indication information, the first PCF network element obtains, according to the identifier of the terminal, the identifier of the PDU session of the terminal and the identifier of the second PCF corresponding to the identifier of the PDU session of the terminal, and sends the indication information to the second PCF network element corresponding to the identifier of the PDU session of the terminal.

Step 903, after receiving the indication information sent by the first PCF network element, the second PCF network element sends the indication information to the SMF network element/UPF network element corresponding to the PDU session.

And step 904, the SMF network element/UPF network element receives the indication information and returns a successful response to the second PCF network element.

Here, the indication information includes the identity of the terminal and the identity of the STUN server. Further, a possible implementation manner is that the SMF network element receives the indication information, notifies the UPF network element to start monitoring of the first response message sent by the STUN server to the terminal, and returns a successful response to the second PCF network element.

Step 905, the second PCF network element returns the first response message to the first PCF network element.

Step 906, after receiving the first response message, the first PCF network element returns a second response message to the AF network element.

Step 907, after receiving the second response message returned by the first PCF network element, the AF network element returns a registration response message to the terminal, where the registration response message includes the identifier of the STUN server, that is, the identifier is the same as the identifier of the STUN server included in the indication information.

In step 908, the terminal sends a binding request message to the STUN server.

In step 909, after receiving the binding request message from the terminal, the STUN server returns a first response message to the terminal.

Step 910, the SMF network element/UPF network element monitors a first response message sent by the STUN server, and inserts the IP address of the PDU session allocated to the terminal into the first response message to obtain a second response message.

And 911, the SMF network element/UPF network element sends the second response message to the terminal.

In step 912, the terminal receives a second response message.

Step 913, the terminal sends a first message to the AF network element, where the first message carries the IP address of the PDU session.

Step 914, after receiving the first message, the AF network element obtains the IP address of the PDU session from the first message, and sends a QoS control request message to a second PCF network element, where the QoS control request message includes the IP address of the PDU session.

Step 915, the second PCF network element performs QoS control on the PDU session according to the IP address of the PDU session.

(2) In a specific implementation, some steps described in the above flow are not necessary, for example, the application function network element may also send the indication information to the first PCF network element under the trigger of other factors, in this case, step 900 may not be included, and in step 901, the AF network element does not need to use the successful terminal registration as a precondition for sending the indication information to the first PCF network element, and specifically, the above steps may be appropriately added or deleted according to an actual situation or an actual need; alternatively, some steps may be performed using other alternatives, which are not limited in this application.

It should be understood that the second embodiment and the third embodiment are examples in which the QoS control method described in the first embodiment is applied to different communication systems, and the difference from the first embodiment is that the execution body involved in the step flow is different, and other contents may be referred to each other between different embodiments.

For the above method flow, the present application also provides a communication device, and the specific implementation of the communication device may refer to the above method flow.

Based on the foregoing embodiment, fig. 10 is a schematic structural diagram of a communication device provided in the embodiment of the present application, where the communication device may be any one of an application function network element, a first policy control network element, a second policy control network element, a policy execution network element, and a terminal. As shown in fig. 10, the communication apparatus 1000 includes: a processing module 1001 and a transceiver module 1002;

when the communication device 1000 is an application function network element:

a processing module 1001, configured to determine indication information, where the indication information includes an identifier of the terminal and policy information, where the policy information includes an identifier of a STUN server, and the indication information is used to indicate that an IP address of a PDU session of the terminal is inserted in a first reply message sent by the STUN server to the terminal;

a transceiver module 1002, configured to send the indication information to the first policy control network element.

In a possible design, if the status is start, after the transceiver module 1002 sends the indication information to the first policy control network element, the transceiver module is further configured to:

When the communication device 1000 is a first policy control network element:

a transceiver module 1002, configured to receive indication information from an application function network element, where the indication information includes an identifier of a terminal and policy information, the policy information includes an identifier of a STUN server, and the indication information is used to indicate that an IP address of a PDU session of the terminal is inserted in a first response message sent by the STUN server to the terminal;

a processing module 1001, configured to obtain, according to the identifier of the terminal, an identifier of a PDU session of the terminal and a second policy control network element corresponding to the identifier of the PDU session of the terminal;

the transceiver module 1002 is further configured to send the indication information to a second policy control network element corresponding to the PDU session identifier of the terminal.

In one possible design, the policy information further includes a status;

the processing module 1001 is specifically configured to:

obtaining a record of the terminal according to the identifier of the terminal;

if the status is start and the record of the terminal does not have the policy sub-content corresponding to the policy information, the indication information is sent to a second policy control network element corresponding to the PDU session identifier of the terminal through the transceiver module 1002; alternatively, the first and second electrodes may be,

if the state is stop and the record of the terminal has the policy sub-content corresponding to the policy information, deleting the policy sub-content corresponding to the policy information from the record of the terminal, and sending the indication information to a second policy control network element corresponding to the PDU session identifier of the terminal through the transceiver module 1002.

In a possible design, after the transceiver module 1002 sends the indication information to the second policy control network element corresponding to the identifier of the PDU session of the terminal, the transceiver module is further configured to:

receiving a second notification message from a second policy control network element, wherein the second notification message comprises an identifier of the terminal and PDU session update information;

the processing module 1001 is further configured to: and the PDU session update information is used for updating the record of the terminal according to the PDU session update information.

the processing module 1001 is specifically configured to:

In one possible design, the transceiver module 1002 is further configured to:

after the processing module 1001 adds the first PDU session sub-content to the record of the terminal, the indication information is sent to the second policy control network element corresponding to the identifier of the first PDU session.

When the communication device 1000 is a second policy control network element:

the processing module 1001 receives indication information from a first policy control network element through the transceiving module 1002, where the indication information includes an identifier of a terminal and policy information, the policy information includes an identifier of a STUN server, and the indication information is used to indicate that an IP address of a PDU session of the terminal is inserted in a first response message sent by the STUN server to the terminal; and sending the indication information to a policy enforcement network element.

In one possible design, the transceiver module 1002 is further configured to:

When the communication device 1000 is a policy enforcement network element:

a transceiver module 1002, configured to receive indication information from a second policy control network element, where the indication information includes an identifier of a terminal and policy information, and the policy information includes an identifier of a STUN server;

a processing module 1001, configured to insert an IP address of a PDU session of the terminal into a first response message after monitoring that the first response message is sent to the terminal by the STUN server according to the identifier of the STUN server, so as to obtain a second response message;

the transceiver module 1002 is further configured to send the second response message to the terminal.

When the communication device 1000 is a terminal:

a transceiver module 1002, configured to send a binding request message to a STUN server; receiving a second response message sent by a policy enforcement network element, wherein the second response message is obtained by the policy enforcement network element after inserting the IP address of the PDU session of the terminal into the received first response message returned by the STUN server;

a processing module 1001, configured to obtain an IP address of the PDU session of the terminal from the second response message, and send a first message to an application function network element through the transceiving module 1002, where the first message includes the IP address of the PDU session of the terminal.

It should be noted that, in the embodiment of the present application, the division of the module is schematic, and is only one logic function division, and there may be another division manner in actual implementation. Each functional module in the embodiments of the present application may be integrated into one processing module, or each module may exist alone physically, or two or more modules are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode.

The integrated module, if implemented in the form of a software functional module and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be substantially implemented or contributed by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, a network device, or the like) or a processor (processor) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

Based on the above embodiments, fig. 11 is a schematic structural diagram of another communication device provided in the embodiments of the present application. The communication device may be any one of an application function network element, a first policy control network element, a second policy control network element, a policy enforcement network element, and a terminal, and is configured to implement corresponding processes or steps in the method embodiments shown in fig. 6a to fig. 9. The communication apparatus has the function of the communication apparatus 1000 shown in fig. 10. Referring to fig. 11, the communication device 1100 includes: a communication module 1101, a processor 1102;

the communication module 1101 is configured to perform communication interaction with other devices. The communication module 1101 may be an RF circuit, a Wi-Fi module, a communication interface, a bluetooth module, etc.

The processor 1102 is configured to implement the functions of the processing module in fig. 10.

Optionally, the communication apparatus 1100 may further include: the memory 1104 is used for storing programs and the like. In particular, the program may comprise program code comprising instructions. The memory 1104 may comprise RAM and may also include non-volatile memory, such as at least one disk storage. The processor 1102 executes the application programs stored in the memory 1104 to implement the functions described above.

In one possible approach, the communication module 1101, the processor 1102 and the memory 1104 are communicatively coupled. For example, the communication module 1101, the processor 1102, and the memory 1104 may be connected to each other by a bus 1103; the bus 1103 may be a PCI bus or an EISA bus, etc. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown in FIG. 11, but this is not intended to represent only one bus or type of bus.

In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the invention to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website site, computer, server, or data center to another website site, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that incorporates one or more of the available media. The usable medium may be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others. Embodiments of the present invention are described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams 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.

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.

It will be apparent to those skilled in the art that various modifications and variations can be made in the embodiments of the present invention without departing from the spirit and scope of the application. Thus, if such modifications and variations of the embodiments of the present invention fall within the scope of the claims of the present application and their equivalents, the present application is also intended to encompass such modifications and variations.

Claims

1. A quality of service, QoS, control method, the method comprising:

an application function network element receives a first message from a terminal, wherein the first message comprises an IP address of a PDU session of the terminal; the IP address of the PDU session of the terminal is inserted into a first response message after a strategy execution network element monitors that the first response message is sent to the terminal by a STUN server;

2. The method of claim 1, further comprising:

the application function network element determines indication information, wherein the indication information comprises an identifier of the terminal and policy information, the policy information comprises an identifier of the STUN server, and the indication information is used for indicating that an IP address of a PDU session of the terminal is inserted into a first response message sent to the terminal by the STUN server;

3. The method according to claim 2, wherein the policy information further includes a status indicating that the IP address of the PDU session of the terminal is inserted in the first reply message sent by the STUN server to the terminal when the status is start.

4. A QoS control method, characterized in that the method comprises:

a second policy control network element receives a QoS control request message from an application function network element, wherein the QoS control request message comprises an IP address of a PDU session of a terminal, and the IP address of the PDU session of the terminal is inserted in a first response message which is sent to the terminal by an STUN server and monitored by a policy execution network element;

and the second strategy control network element performs QoS control on the PDU session according to the IP address of the PDU session of the terminal.

5. The method of claim 4, further comprising:

the second policy control network element receives indication information from the first policy control network element, wherein the indication information comprises an identifier of a terminal and policy information, the policy information comprises an identifier of the STUN server, and the indication information is used for indicating that an IP address of a PDU session of the terminal is inserted into a first response message sent to the terminal by the STUN server;

6. The method according to claim 4 or 5, characterized in that the method further comprises:

the second policy control network element receives a first notification message from the policy enforcement network element, where the first notification message includes an identifier of the terminal and PDU session update information;

7. A QoS control method, characterized in that the method comprises:

the terminal sends a binding request message to the STUN server;

and the terminal obtains the IP address of the PDU session of the terminal from the second response message and sends a first message to an application function network element, wherein the first message comprises the IP address of the PDU session of the terminal, so that a QoS control request message sent to a second strategy control network element by the application function network element comprises the IP address of the PDU session.

8. The method of claim 7, wherein the first message is a call request message or a call answer message.

9. An application function network element, wherein the application function network element comprises:

a transceiver module, configured to receive a first message from a terminal, where the first message includes an IP address of a PDU session of the terminal; the IP address of the PDU session of the terminal is inserted into a first response message after a strategy execution network element monitors that the first response message is sent to the terminal by a STUN server;

the processing module is used for obtaining the IP address of the PDU conversation of the terminal according to the first message;

the transceiver module is further configured to obtain an IP address of the PDU session of the terminal according to the first message, and send a QoS control request message to a second policy control network element, where the QoS control request message includes the IP address of the PDU session.

10. The network element of claim 9, wherein the processing module is further configured to determine indication information, the indication information includes an identifier of the terminal and policy information, the policy information includes an identifier of a STUN server, and the indication information is used to indicate that an IP address of a PDU session of the terminal is inserted in a first response message sent by the STUN server to the terminal;

the transceiver module is further configured to send the indication information to a first policy control network element.

11. The network element of claim 10, wherein the policy information further comprises a status, and wherein the status is start or stop.

12. A policy control network element, wherein the policy control network element comprises:

a receiving and sending module, configured to receive a QoS control request message from an application function network element, where the QoS control request message includes an IP address of a PDU session of a terminal, and the IP address of the PDU session of the terminal is inserted in a first response message sent to the terminal by a STUN server after a policy enforcement network element monitors the first response message;

and the processing module is used for performing QoS control on the PDU session according to the IP address of the PDU session of the terminal.

13. The policy control network element according to claim 12, wherein said transceiver module is further configured to: receiving indication information from a first policy control network element, wherein the indication information comprises an identifier of the terminal and policy information, the policy information comprises an identifier of the STUN server, and the indication information is used for indicating that an IP address of a PDU session of the terminal is inserted into a first response message sent to the terminal by the STUN server; and sending the indication information to a policy enforcement network element.

14. The policy control network element according to claim 12 or 13, wherein said transceiver module is further configured to: receiving a first notification message from a policy enforcement network element, wherein the first notification message comprises an identifier of the terminal and PDU session update information; and sending a second notification message to a first policy control network element according to the first notification message, wherein the second notification message comprises the identifier of the terminal and the PDU session update information.

15. A terminal, characterized in that the terminal comprises:

and the processing module is used for obtaining the IP address of the PDU session of the terminal from the second response message and sending a first message to an application function network element through the transceiver module, wherein the first message comprises the IP address of the PDU session of the terminal, so that a QoS control request message sent to a second policy control network element by the application function network element comprises the IP address of the PDU session.

16. The terminal of claim 15, wherein the first message is a call request message or a call answer message.

17. A communication system, the communication system comprising: the terminal, the strategy execution network element, the application function network element and the second strategy control network element;

the terminal is used for: sending a binding request message to the STUN server;

the policy enforcement network element is to: after receiving a first response message sent by the STUN server based on the binding request message, inserting an IP address of a PDU session of the terminal into the first response message to obtain a second response message, and sending the second response message to the terminal;

the terminal is further configured to: receiving the second response message sent by the policy enforcement network element; and obtaining the IP address of the PDU session of the terminal from the second response message, and sending a first message to an application function network element, wherein the first message comprises the IP address of the PDU session of the terminal;

the application function network element is configured to: receiving the first message from the terminal, obtaining an IP address of a PDU session of the terminal according to the first message, and sending a QoS control request message to a second policy control network element, wherein the QoS control request message comprises the IP address of the PDU session;

the second policy control network element is configured to: and receiving a QoS control request message from the application function network element, and performing QoS control on the PDU session according to the IP address of the PDU session of the terminal.

18. The communication system according to claim 17, wherein the communication system further comprises a first policy control network element;

the application function network element is further configured to: determining indication information, wherein the indication information comprises an identifier of the terminal and policy information, the policy information comprises an identifier of the STUN server, and the indication information is used for indicating that an IP address of a PDU session of the terminal is inserted into a first response message sent to the terminal by the STUN server; and sending the indication information to a first policy control network element;

the first policy control network element is configured to: receiving the indication information from an application function network element, obtaining a PDU session identifier of the terminal and the second policy control network element corresponding to the PDU session identifier of the terminal according to the identifier of the terminal, and sending the indication information to the second policy control network element;

the second policy control network element is further configured to: receiving indication information from the first policy control network element and sending the indication information to the policy enforcement network element;

the policy enforcement network element is to: receiving the indication information from the second policy control network element.

19. The communication system of claim 18, wherein the policy information further includes a status;

the first policy control network element is specifically configured to: obtaining a record of the terminal according to the identifier of the terminal;

if the state is starting and the strategy subcontent corresponding to the strategy information does not exist in the record of the terminal, the indication information is sent to a second strategy control network element corresponding to the PDU conversation identification of the terminal; alternatively, the first and second electrodes may be,

and if the state is stop and the strategy subcontent corresponding to the strategy information exists in the record of the terminal, deleting the strategy subcontent corresponding to the strategy information from the record of the terminal and sending the indication information to a second strategy control network element corresponding to the PDU conversation identifier of the terminal.

20. The communication system of claim 18, wherein the first policy control network element is further configured to: receiving a second notification message from a second policy control network element, wherein the second notification message comprises an identifier of the terminal and PDU session update information; and obtaining the record of the terminal according to the identifier of the terminal, and updating the record of the terminal according to the PDU session updating information.

21. The communication system of claim 20, wherein the PDU session update information includes an identification of a first PDU session and an update type of the first PDU session;

the first policy control network element is specifically configured to: if the update type of the first PDU session is newly increased, the first policy control network element adds a first PDU session sub-content in the record of the terminal, wherein the first PDU session sub-content comprises the identifier of the first PDU session and the identifier of the second policy control network element corresponding to the identifier of the first PDU session; or, if the update type of the first PDU session is deletion, the first policy control network element deletes a second PDU session sub-content from the record of the terminal, where the second PDU session sub-content includes an identifier of the first PDU session.