CN110730487B

CN110730487B - Method, device and system for selecting session management function network element

Info

Publication number: CN110730487B
Application number: CN201810783829.1A
Authority: CN
Inventors: 钱宏; 胡翔; 薛原; 陈曦
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2018-07-17
Filing date: 2018-07-17
Publication date: 2020-12-08
Anticipated expiration: 2038-07-17
Also published as: CN110730487A; WO2020015503A1

Abstract

A method, device and system for selecting a session management function network element are provided, wherein the method for selecting the session management function network element comprises the following steps: determining whether a user plane function network element meeting a screening condition exists, if the user plane function network element meeting the screening condition exists, sending first state information of the session management function network element to a network function repository function network element, wherein the first state information of the session management function network element is used for indicating that the session management function network element is available under the screening condition, and the first state information is used for selecting the session management function network element, so that the session management function network element can be selected according to the state of the session management function network element in the subsequent selection process, the available session management function network element can be ensured to be selected as much as possible, and the time delay of a session creation process is reduced.

Description

Method, device and system for selecting session management function network element

Technical Field

The present application relates to the field of communications technologies, and in particular, to a method, an apparatus, and a system for selecting a session management function network element.

Background

In the procedure of creating a Packet Data Unit (PDU) session (session), a process of selecting a Session Management Function (SMF) by an access and mobility management function (AMF) and a process of selecting a User Plane Function (UPF) by the SMF are included. When selecting the SMF, the AMF selects the SMF meeting a certain parameter requirement, for example, the AMF may send the certain parameter requirement to a network function repository function (NRF), and the NRF selects the SMF meeting the parameter requirement and sends the selection result to the AMF.

With the selection in the prior art, there may be a case: the AMF selects an SMF, but when selecting a UPF, the SMF does not select a UPF that meets certain parameter requirements, i.e., there is no UPF available for the SMF, which means that the SMF selected by the AMF is invalid, resulting in a failure to activate.

It can be seen that this selection of SMF is inefficient, which causes a large delay to the PDU session creation process.

Disclosure of Invention

The embodiment of the application provides a method, a device and a system for selecting a network element with a session management function, which are used for improving the efficiency of selecting the network element with the session management function and reducing the time delay in the process of creating a session.

In a first aspect, a first method for selecting a session management function network element is provided, the method being performed by a session management function network element, such as SMF in a 5G system. The method comprises the following steps: and determining whether a user plane function network element meeting the screening condition exists, if so, sending the first state information of the session management function network element to a network function repository function network element, wherein the first state information of the session management function network element is used for indicating that the session management function network element is available under the screening condition, and the first state information of the session management function network element is used for selecting the session management function network element.

In the embodiment of the present application, the status of the session management function network element is determined according to the condition of the user plane function network element, if there is a user plane function network element that meets the screening condition, the status of the session management function network element is an available status under the screening condition, and first status information indicating that the session management function network element is available under the screening condition is sent to the network function repository function network element, so that when the network function repository function network element subsequently selects the session management function network element under the screening condition, the network function repository function network element can perform selection according to the status of the session management function network element, for example, only the session management function network element with the first status information can be selected, that is, only the session management function network element that is available under the screening condition is selected, so as to ensure that the selected session management function network element has an available user plane function network element as much as possible, therefore, the probability of reselecting the session management function network element caused by the fact that the selected session management function network element has no available user plane function network element is reduced, the efficiency of selecting the session management function network element is improved, the time delay of the session creation process is reduced, and the activation rate is also improved.

In one possible implementation, the first state information includes: information indicating that the session management function network element is available under the screening condition; or, indicating the session management function network element to have the information of the user plane function network element meeting the screening condition.

That is to say, the first status information may have two indication manners, where the first indication manner may be referred to as an implicit indication manner, and is to indicate that the session management function network element is available, and the session management function network element is available under the screening condition, that is, the session management function network element has an available user plane function network element under the screening condition, and therefore, the implicit indication manner is to indicate whether the session management function network element has an available user plane function network element by indicating whether the session management function network element is available. The second indication manner may be referred to as an explicit indication manner, which indicates that the session management function network element has a user plane function network element that satisfies the screening condition, that is, the explicit indication manner directly indicates whether the session management function network element has an available user plane function network element. Through an implicit indication mode, the availability of the session management function network element can be determined, the availability of the user plane function network element can also be determined, and double contents can be determined through one indication; and the user plane functional network element available for the session management functional network element can be directly determined through the explicit indication, and the indication mode is more direct. As to which indication mode is used for the first status information, the first status information may be predefined by a protocol, or determined by negotiation between network elements in advance, and the like, which is not limited specifically.

In a possible implementation manner, determining whether there is a user plane function network element that meets the screening condition may include: acquiring information of at least one user plane functional network element, and determining whether the at least one user plane functional network element has a user plane functional network element meeting the screening condition according to the acquired information of the at least one user plane functional network element; or, the information of the user plane functional network element is not acquired, and the user plane functional network element which does not meet the screening condition is determined.

Since it is determined whether there are user plane functional network elements that meet the screening conditions, it is conceivable to acquire information of the user plane functional network elements, and thus determine whether the user plane functional network elements meet the screening conditions according to the information of the user plane functional network elements. However, the information of the user plane functional network element may or may not be obtained. In the embodiment of the present application, if the information of the user plane function network element is obtained, it may be determined whether the user plane function network elements meet the screening condition according to the information of the user plane function network element, and if the information of the user plane function network element is not obtained, it may be directly determined that the user plane function network element does not meet the screening condition. Therefore, whether the information of the user plane function network element can be acquired or not, whether the user plane function network element meeting the screening condition exists or not can be determined according to the embodiment of the application.

In a possible implementation manner, the obtaining information of at least one user plane function network element may include: receiving information of at least one user plane function network element from at least one user plane function network element, wherein the information of one user plane function network element is from one user plane function network element; or, sending a subscription message to the network function repository function network element, where the subscription message is used to subscribe the information of the user plane function network element that meets the screening condition, and receiving a notification message from the network function repository function network element, and obtaining the information of at least one user plane function network element according to the notification message.

The information of the user plane functional network element may be obtained in different manners, for example, the information of the user plane functional network element may be obtained by directly interacting with the user plane functional network element, and the obtaining manner is relatively direct. Or, a subscription can be initiated to the network function repository function unit, and the information of the user plane function network element is obtained through the subscription process, so that the interaction with too many user plane function network elements is not needed, the interaction process between devices is reduced, and the information of the user plane function network element can be continuously obtained through one subscription, so that the method is simple.

In one possible implementation, the screening conditions include at least one of DNN and S-NSSAI.

For example, the screening conditions comprise DNN, or the screening conditions comprise S-NSSAI, or the screening conditions comprise DNN and S-NSSAI. Of course, the screening conditions include parameters not limited thereto, for example, the screening conditions may include other parameters besides at least one of DNN and S-NSSAI, for example, the screening conditions include S-NSSAI and other parameters, or the screening conditions may not include DNN and S-NSSAI but include other parameters, without limitation.

In a possible implementation manner, if there is no user plane function network element that meets the screening condition, sending second state information of the session management function network element to the network function repository function network element, where the second state information of the session management function network element is used to indicate that the session management function network element is unavailable under the screening condition; or, if there is no user plane function network element meeting the screening condition, sending a deletion instruction to a network function repository function network element, where the deletion instruction is used to instruct the network function repository function network element, and deleting the information of the session management function network element from the information of the session management function network element available under the screening condition.

For example, the network function repository function network element stores state information of the session management function network element, and for a session management function network element, the state information of the session management function network element includes first state information or second state information of the session management function network element. If there is no user plane function network element meeting the screening condition, the second state information of the session management function network element may be sent to the network function repository function network element, so that the network function repository function network element may store the first state information of the session management function network element and also may store the second state information of the session management function network element, thereby determining what state the session management function network element is. Alternatively, the network function repository function network element may only store the first state information of the session management function network element, that is, the session management function network element in which the network function repository function network element stores the first state information is all the session management function network elements available under some or several screening conditions. Then, if the state information of the session management function network element is the second state information, a deletion instruction may be sent to the network function repository function network element, so that the network function repository function network element may delete the information of the session management function network element, that is, the session management function network element is no longer available. Therefore, when the network function repository function network element stores the state of the session management function network element, different storage modes can be adopted, and the method is flexible.

In a possible implementation manner, the screening condition is specifically a first screening condition, and then determining whether there is a user plane function network element that meets the screening condition may include: determining whether a user plane functional network element meeting the first screening condition exists; or, the screening condition is specifically the second screening condition and the third screening condition, and then determining whether there is a user plane functional network element that meets the screening condition may include: and determining whether the user plane functional network element meeting the second screening condition exists or not, and determining whether the user plane functional network element meeting the third screening condition exists or not.

The screening conditions may be one or more. For example, if the screening condition is one, and the screening condition is referred to as a first screening condition, it may be directly determined whether there is a user plane functional network element that meets the first screening condition; or the screening conditions are multiple, for example, the screening conditions include a second screening condition and a third screening condition, then it can be determined whether there is a user plane functional network element that satisfies the screening conditions for each screening condition, so as to avoid missing the screening conditions.

In a possible implementation manner, if there is a user plane function network element that meets the screening condition, sending the first state information of the session management function network element to a network function repository function network element, where the first state information of the session management function network element is used to indicate that the session management function network element is available under the screening condition, including:

the screening condition is specifically a first screening condition, and if a user plane function network element meeting the first screening condition exists, the first state information of the session management function network element is sent to a network function repository function network element, and the first state information of the session management function network element is used for indicating that the session management function network element is available under the first screening condition;

or the like, or, alternatively,

the screening conditions are specifically a second screening condition and a third screening condition, if a user plane function network element meeting the second screening condition exists, the first state information of the session management function network element is sent to a network function repository function network element, and the first state information of the session management function network element is used for indicating that the session management function network element is available under the second screening condition; or, if there is a user plane function network element that meets the third screening condition, sending the first state information of the session management function network element to a network function repository function network element, where the first state information of the session management function network element is used to indicate that the session management function network element is available under the third screening condition.

It can be seen that for each screening condition, there may be corresponding first status information, and even if one session management function network element is not available under a certain screening condition, it is likely to be available under other screening conditions, so that one session management function network element may exhibit multiple characteristics, and the practicability is stronger. Of course, if the first status information of the session management function network element under the second screening condition and the first status information of the session management function network element under the third screening condition are to be sent to the network function repository function network element, two pieces of the first status information may be sent, or only one piece of the first status information may be sent, and this piece of the first status information can be used as the first status information of the session management function network element under the second screening condition and the first status information of the session management function network element under the third screening condition.

In a possible implementation manner, in a case that the screening condition is specifically a first screening condition, if the first screening condition is null, it indicates that the first screening condition is used for screening all user plane functional network elements; or, in the case that the screening condition is specifically the second screening condition and the third screening condition, if at least one of the second screening condition and the third screening condition is null, it indicates that at least one of the second screening condition and the third screening condition is used for screening all the user plane functional network elements.

A screening condition may or may not correspond to at least one parameter, i.e. the screening condition is empty. Then the embodiment of the present application considers that if a screening condition is null, it indicates that the screening condition is used for screening all the user plane functional network elements. Of course, all the user plane functional network elements screened here should be user plane functional network elements capable of working normally.

In a possible implementation manner, the first state information of the session management function network element includes parameter information corresponding to the screening condition, and includes indication information for indicating that the session management function network element is available under the screening condition; or, the first status information of the session management function network element includes identification information of the screening condition and includes indication information for indicating that the session management function network element is available under the screening condition.

The parameter information corresponding to the screening condition can represent the corresponding screening condition, so that the first state information can directly include the parameter information corresponding to the screening condition, and the corresponding screening condition can be determined more directly. Or, identification information may also be set for the screening condition, for example, if one identification information is a serial number, the corresponding screening condition can be determined by the identification information, which is simpler, and the data amount of the identification information of the screening condition is generally smaller than that of the parameter information, thereby helping to reduce the data amount of the first state information.

In a second aspect, a second method of selecting a session management function network element is provided, the method being executable by a network function repository function network element, such as an NRF, in a 5G system. The method comprises the following steps: receiving a request message from the mobility management function network element, where the request message is used to request to obtain information of a session management function network element that meets the fourth screening condition, determining whether there is an available session management function network element that meets the fourth screening condition according to state information of at least one session management function network element, where the state information of at least one session management function network element is used to indicate whether the at least one session management function network element is in an available state under the fourth screening condition, and sending a screening result to the mobility management function network element.

When selecting the session management function network element, the selection may be performed according to state information of the session management function network element, where the state information of the session management function network element is used to indicate whether the session management function network element is in an available state under the fourth screening condition, where the session management function network element is in the available state under the fourth screening condition, which may mean that the session management function network element has a user plane function network element that satisfies the fourth screening condition. Therefore, the session management function network element is selected according to the state information of the session management function network element, so that the selected session management function network element can be ensured to have an available user plane function network element as much as possible, the subsequent session creation process can be sequentially carried out, the selection failure of the session management function network element due to the fact that the selected session management function network element does not have the available user plane function network element is avoided, the efficiency of selecting the session management function network element is improved, the time delay of the session creation process is reduced, and the activation rate is also improved.

In one possible implementation, the state information of a session management function network element includes: information indicating that one session management function network element is an available session management function network element satisfying the fourth screening condition, or information indicating that one session management function network element is an unavailable session management function network element satisfying the fourth screening condition; or, the information indicating that one session management function network element has the user plane function network element satisfying the fourth screening condition, or the information indicating that one session management function network element does not have the user plane function network element satisfying the fourth screening condition.

When the implementation of the first aspect is introduced, it is introduced that the first state information of the session management function network element may have two indication manners, namely an implicit indication manner and an explicit indication manner, and then similarly, the state information of the session management function network element also has two indication manners, namely an implicit indication manner and an explicit indication manner. The specific selection of which indication mode is selected can be predefined by a protocol, or determined by negotiation between network elements, and the like.

In a possible implementation manner, the screening result is specifically information of K session management function network elements, where the information of K session management function network elements is used to indicate that the K session management function network elements are available session management function network elements that satisfy the screening condition; or, the screening information is specifically a failure indication, where the failure indication indicates that there is no available session management function network element that satisfies the fourth screening condition.

After the selection is completed, an available session management function network element that satisfies the fourth filtering condition may be selected, or an available session management function network element that does not satisfy the fourth filtering condition may not be selected. Then, if an available session management function network element satisfying the fourth screening condition is selected, the information of the selected available session management function network element satisfying the fourth screening condition may be directly sent to the mobility management function network element as the screening condition, and if an available session management function network element satisfying the fourth screening condition is not selected, a failure indication may also be sent to the mobility management function network element, so that the mobility management function network element can specify a corresponding screening result regardless of whether an available session management function network element satisfying the fourth screening condition can be selected.

In one possible implementation, the state information of the at least one session management function network element is from the at least one session management function network element.

That is to say, the session management function network element may determine the state information of the session management function network element, and send the state information of the session management function network element to the network function repository function network element, so that the network function repository function network element performs selection according to the state information of the session management function network element. In this case, a session management function network element generally only can determine the status information of the session management function network element, and therefore, the network function repository function network element may interact with at least one session management function network element to obtain the status information of at least one session management function network element.

In a possible implementation manner, the state information of one session management function network element in the at least one session management function network element includes parameter information corresponding to at least one screening condition, and includes indication information for indicating whether the one session management function network element is available under each of the at least one screening condition, where the at least one screening condition includes a fourth screening condition; or, the status information of one of the at least one session management function network element includes identification information of at least one screening condition, and includes indication information for indicating whether the one session management function network element is available under each of the at least one screening condition, where the at least one screening condition includes a fourth screening condition.

The parameter information corresponding to the screening condition can represent the corresponding screening condition, so that the first state information can directly include the parameter information corresponding to the screening condition, and the corresponding screening condition can be determined more directly. Or, identification information may also be set for the screening condition, for example, if one identification information is a serial number, the corresponding screening condition can be determined by the identification information, which is simpler, and the data amount of the identification information of the screening condition is generally smaller than that of the parameter information, thereby helping to reduce the data amount of the first state information. Furthermore, the status information of a session management function network element may include information corresponding to at least one screening condition, so that a session management function network element may exhibit one or more characteristics.

In a third aspect, a system for selecting a session management function network element is provided, and the system may include a session management function network element and a network function repository function network element. The session management function network element is used for determining whether a user plane function network element meeting a screening condition exists, and if the user plane function network element meeting the screening condition exists, sending first state information of the session management function network element to a network function repository function network element, wherein the first state information of the session management function network element is used for indicating that the management function network element is available under the screening condition, and the first state information is used for selecting the session management function network element; and the network function storage library function network element is used for receiving the first state information.

For technical effects brought by the third aspect or the possible implementation manner of the third aspect, reference may be made to technical effects brought by different implementation manners of the first aspect or the first aspect, which are not described herein again.

In one possible implementation, the network function repository function network element is further configured to:

receiving a request message from a mobility management function network element, where the request message is used to request to obtain information of a session management function network element that meets a fourth screening condition, where the session management function network element that meets the fourth screening condition is a user plane function network element that has a user plane function meeting the fourth screening condition; determining whether an available session management function network element meeting a fourth screening condition exists according to the state information of the at least one session management function network element, wherein the state information of the at least one session management function network element is used for indicating whether the at least one session management function network element is in an available state under the fourth screening condition; and sending the screening result to a mobility management function network element.

The system for selecting a session management function network element provided in the third aspect may further include a mobility management function network element, or certainly may not include the mobility management function network element, and is not limited specifically.

For technical effects brought by the possible implementation manner of the third aspect, reference may be made to the technical effects brought by the second aspect, which is not described herein again.

In a fourth aspect, the present application provides an apparatus, which may be a session management function network element or a network function repository function network element, or may be a chip. The apparatus has the functionality to implement the embodiments of any of the first, second or third aspects described above. The function can be realized by hardware, and can also be realized by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the functions described above.

In a fifth aspect, an apparatus is provided, comprising: a processor and a memory; the memory is configured to store computer executable instructions which, when the apparatus is run, the processor is configured to execute the computer executable instructions stored by the memory to cause the apparatus to perform the method of selecting a session management function network element as described in any one of the first aspect or the first aspect, or to cause the apparatus to perform the method of selecting a session management function network element as described in any one of the second aspect or the second aspect, or to cause the apparatus to perform the method of selecting a session management function network element as described in any one of the third aspect or the third aspect.

In a sixth aspect, the present application also provides a computer-readable storage medium having stored therein instructions, which, when run on a computer, cause the computer to perform the method of the above aspects.

In a seventh aspect, the present application also provides a computer program product comprising instructions which, when run on a computer, cause the computer to perform the method of the above aspects.

In the embodiment of the present application, when selecting the session management function network element, the network function repository function network element may select according to the state of the session management function network element, so as to improve the efficiency of selecting the session management function network element, reduce the time delay in the process of creating a session, and improve the activation rate.

These and other aspects of the present application will be more readily apparent from the following description of the embodiments.

Drawings

Fig. 1 is a schematic diagram of a system for selecting a session management function network element according to an embodiment of the present application;

fig. 2 is a schematic diagram of a network architecture of a non-roaming scenario applied in the embodiment of the present application;

fig. 3 is a schematic diagram of a network architecture of a local breakout roaming scenario applied in an embodiment of the present application;

fig. 4 is a schematic diagram of a network architecture of a home routing roaming scenario applied in the embodiment of the present application;

fig. 5 is a process of selecting an SMF by an AMF in a flow of creating a PDU session;

fig. 6 is a process of selecting a UPF by an SMF in a flow of creating a PDU session;

fig. 7 is a flowchart of a method for selecting an SMF according to an embodiment of the present disclosure;

fig. 8 is a flowchart of another method for selecting an SMF according to an embodiment of the present disclosure;

fig. 9 is a flowchart of another method for selecting an SMF according to an embodiment of the present disclosure;

FIG. 10 is a schematic view of an apparatus provided in accordance with an embodiment of the present application;

fig. 11 is a schematic diagram of another apparatus provided in the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in further detail with reference to the accompanying drawings.

Hereinafter, some terms in the embodiments of the present application are explained to facilitate understanding by those skilled in the art.

1) Network elements, or network devices, include, for example, access network elements, or access network devices, such as base stations (e.g., access points) and user plane function network elements.

A base station may refer to, among other things, a device in an access network that communicates over the air-interface, through one or more cells, with wireless terminal devices. The network element may be configured to interconvert received air frames and Internet Protocol (IP) packets as a router between the terminal device and the rest of the access network, which may include an IP network. The network element may also coordinate the management of attributes for the air interface. For example, the network element may include an evolved Node B (NodeB or eNB or e-NodeB) in a Long Term Evolution (LTE) system or an evolved LTE system (LTE-Advanced, LTE-a), or may also include a next generation Node B (gNB) in a fifth generation mobile communication technology (5G) New Radio (NR) system, or may also include a Centralized Unit (CU) and a Distributed Unit (DU) in a cloud access network (cloud ran) system, which is not limited in the embodiments of the present application.

The user plane functional network element, in a fourth generation mobile communication technology (4G) system, for example, includes a Serving Gateway (SGW) and a packet data network gateway (PDN-GW), and in a 5G system, for example, includes an UPF, which is mainly responsible for connecting to an external network. It is considered that UPF in the 5G system corresponds to the combination of SGW and PDN-GW in the 4G LTE system.

In this embodiment of the present application, the network element further includes a core network element, or referred to as a core network device, in a fourth generation mobile communication technology (4G) system, the core network device includes, for example, a Mobility Management Entity (MME) and the like, and in a 5G system, the core network device includes, for example, a Policy Control Function (PCF), an NRF, an AMF, an SMF, and the like. It can be considered that, after the evolution from 4G to 5G, the function of the MME is separated into AMF and SMF, where AMF is used for managing the mobility context of the user and SMF is used for managing the session context.

2) The terms "system" and "network" in the embodiments of the present application may be used interchangeably. The "plurality" means two or more, and in view of this, the "plurality" may also be understood as "at least two" in the embodiments of the present application. "at least one" is to be understood as meaning one or more, for example one, two or more. For example, including at least one means including one, two, or more, and does not limit which ones are included, for example, including at least one of A, B and C, then included may be A, B, C, A and B, A and C, B and C, or A and B and C. Similarly, the understanding of the description of "at least one" and the like is similar. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, or B exists alone. In addition, the character "/" generally indicates that the preceding and following related objects are in an "or" relationship, unless otherwise specified.

In addition, in order to facilitate clear description of technical solutions of the embodiments of the present application, in the embodiments of the present application, terms such as "first" and "second" are used to distinguish the same items or similar items having substantially the same functions and actions. Those skilled in the art will appreciate that the terms "first," "second," etc. do not define a sequence, order, priority, or degree of importance, etc., and the terms "first," "second," etc. do not define a difference. For example, the "first screening condition" and the "second screening condition" described in the embodiment of the present application may be the same screening condition or different screening conditions, and this is not particularly limited in the embodiment of the present application.

It should be noted that, the session management function network element, the network function repository function network element, the mobility management function network element, the user plane function network element, and the like, and further the SMF, NRF, AMF, UPF, and the like, which are related in the embodiments of the present application, are only names, and the names do not limit the device itself. In the 5G system and other future communication systems, the session management function network element, the network function repository function network element, the mobility management function network element, the user plane function network element, and the like, and further the SMF, NRF, AMF, UPF, and the like, may also be other names, which is not specifically limited in this embodiment of the present application. For example, the UPF may be replaced by UP, etc., and the unified description is provided herein, which will not be described below.

First, an embodiment of the present application provides a system 100 for selecting a session management function network element, as shown in fig. 1, the system 100 may include a session management function network element 101 and a network function repository function network element 102. In fig. 1, a connection line between the session management function network element 101 and the network function repository function network element 102 indicates that the two network elements can communicate, and the two network elements may be connected in a wired manner or in a wireless manner.

The session management function network element 101 may be configured to determine whether there is a user plane function network element that meets a screening condition, and if there is a user plane function network element that meets the screening condition, send first state information of the session management function network element 101 to the network function repository function network element 102, where the first state information of the session management function network element 101 is used to indicate that the session management function network element 101 is available under the screening condition, and the first state information is used to select the session management function network element 101;

a network function repository function network element 102, configured to receive the first status information.

In this embodiment, the parameter requirements to be met are referred to as screening conditions, where when the session management function network element 101 selects the user plane function network element, the selection may be performed according to one screening condition or multiple screening conditions, that is, the number of the screening conditions may be one or multiple, and is not limited specifically. The session management functional network element 101 may obtain information of the user plane functional network element, determine whether there is information of the user plane functional network element that meets the screening condition, and if there is information of the user plane functional network element that meets the screening condition, it indicates that the user plane functional network element to which the information of the user plane functional network element belongs meets the screening condition. If there is a user plane function network element that meets the screening condition, the session management function network element 101 may send the first status information of the session management function network element 101 to the network function repository function network element 102, and of course, if there is a user plane function network element that meets the screening condition, the session management function network element 101 may also determine that the session management function network element 101 is available under the screening condition, and then send the first status information of the session management function network element 101 to the network function repository function network element 102. In addition, if there is a user plane function network element that meets the screening condition, the session management function network element 101 may further set the state of the session management function network element 101 to be an available state under the screening condition.

The status information indicating that the session management function network element 101 is available is referred to herein as first status information of the session management function network element 101. That is to say, although the session management function network element 101 may have a user plane function network element that meets the screening condition after determining whether there is a user plane function network element that meets the screening condition, or may not have a user plane function network element that meets the screening condition, that is, the state of the session management function network element 101 under the screening condition may be an available state or an unavailable state, in this embodiment, the session management function network element 101 may only send the first state information of the session management function network element 101 to the network function repository function network element 102. After the network function repository function network element 102 receives the first status information, it can know which session management function network elements 101 are available under the screening condition.

In this embodiment of the application, the first state information may have different implementation manners, and different implementation manners may implement different indication manners.

For example, the first status information includes information for indicating that the session management function network element 101 is available under the screening condition, and this indication manner of the first status information may be regarded as an implicit indication manner. That is, although the first status information directly indicates that the session management function network element 101 is available under the screening condition, it implicitly indicates that the session management function network element 101 has a user plane function network element that satisfies the screening condition, that is, indicates whether the session management function network element 101 has a user plane function network element available by indicating the status of the session management function network element 101.

As another example, the first status information includes information for indicating that the session management function network element 101 has a user plane function network element that satisfies the screening condition, and this indication manner of the first status information may be regarded as an explicit indication manner. That is, the first status information directly indicates whether the session management function network element 101 has a user plane function network element that satisfies the screening condition, which is simple and direct.

As to the indication manner used by the first status information, it may be predefined by a protocol, or may be determined by negotiation between network elements, and the like, which is not limited specifically.

When the mobility management function network element needs to obtain the information of the session management function network element 101 that satisfies the corresponding screening condition, the mobility management function network element may send a request message to the network function repository function network element 102, and the network function repository function network element 102 receives the request message from the mobility management function network element, for example, the request message is used to request to obtain the information of the session management function network element 101 that satisfies the fourth screening condition, where the session management function network element 101 that satisfies the fourth screening condition is a session management function network element that the session management function network element 101 has a user plane function network element that satisfies the fourth screening condition, that is, the session management function network element 101 is in an available state under the fourth screening condition.

As can be seen from the foregoing description, the session management function network element 101 may send the first status information of the session management function network element 101 to the network function repository function network element 102, so that the network function repository function network element 102 may determine whether there is an available session management function network element 101 that satisfies the fourth filtering condition according to the status information of at least one session management function network element 101, where the status information of at least one session management function network element 101 is used to indicate whether at least one session management function network element 101 is in an available state under the fourth filtering condition. The status information of the session management function network element 101 may include first status information of the session management function network element 101.

After the screening, the network function repository function network element 102 may send a screening result to the mobility management function network element, where the screening result may indicate whether there is an available session management function network element 101 that satisfies the fourth screening condition.

As an optional manner, the system 100 for selecting a session management function network element provided in this embodiment of the application may further include a mobility management function network element, which is not shown in the figure. If the system 100 further comprises a mobility management function network element, the mobility management function network element is capable of communicating with both the session management function network element 101 and the network function repository function network element 102.

It can be seen that, in the embodiment of the present application, the state of the session management function network element 101 is determined according to the condition of the user plane function network element, if there is a user plane function network element that meets the screening condition, the state of the session management function network element 101 is an available state under the screening condition, and the session management function network element 101 may send first state information indicating that the session management function network element 101 is available under the screening condition to the network function repository function network element 102, then the network function repository function network element 102 may select the session management function network element 101 subsequently under the screening condition according to the state of the session management function network element 101, for example, only the session management function network element 101 with the first state information may be selected, that is, only the session management function network element 101 that is available under the screening condition is selected, thus, it is ensured as much as possible that the selected session management function network element 101 has an available user plane function network element, and the effective selection rate of the session management function network element 101 is improved.

In addition, if the mobility management function network element selects an unavailable session management function network element 101 according to the manner in the prior art, the mobility management function network element needs to initiate a process of selecting the session management function network element 101 again and reselect the session management function network element 101, but by adopting the scheme provided by the embodiment of the application, the probability that the session management function network element 101 needs to be reselected due to the fact that the selected session management function network element 101 does not have an available user plane function network element is reduced, the efficiency of selecting the session management function network element 101 is improved, the time delay of creating a session is reduced, and the activation rate is also improved. The session, for example, PDU session, or possibly other sessions, as long as the session in which the mobility management function network element needs to select the session management function network element 101 is all within the protection scope of the embodiment of the present application, and the PDU session is mainly used as an example hereinafter.

The embodiment shown in fig. 1 describes a system 100 for selecting a network element with a session management function according to an embodiment of the present application, and taking application of the system 100 to a 5G system as an example, a network architecture that the system 100 may be applied to the 5G system, or an application scenario of the system 100 in the 5G system is described below. The system 100 provided in the embodiment of the present application may be applied to a 5G system in a scenario including, but not limited to, a non-roaming scenario, a local breakout roaming scenario, and a home routing roaming scenario, which are described below.

Please refer to fig. 2, which is a schematic diagram of a network architecture in a non-roaming scenario. In the network architecture, a Network Slice Selection Function (NSSF), a network open function (NEF), an NRF, a Policy Control Function (PCF), a Unified Data Management (UDM), an Application Function (AF), an authentication service function (AUSF), an AMF, and an SMF are used, and two of the network elements may communicate with each other based on a service method. In fig. 2, NSSF may be regarded as a service interface of NSSF, and similarly, Nnef is a service interface of NEF, Npcf is a service interface of PCF, Nudm is a service interface of UDM, Naf is a service interface of AF, Nausf is a service interface of AUSF, Namf is a service interface of AMF, and Nsmf is a service interface of SMF. In addition, the AMF and the terminal equipment can communicate through AN N1 interface, the AMF and the (R) AN can communicate through AN N2 interface, the SMF and the UPF can communicate through AN N4 interface, the terminal equipment and the (R) AN can communicate over the air, the (R) AN and the UPF can communicate through AN N3 interface, and the UPF and a Data Network (DN) can communicate through AN N6 interface.

For example, the session management function network element 101 provided in the embodiment of the present application may be implemented by an SMF in the network architecture shown in fig. 2, the network function repository function network element 102 provided in the embodiment of the present application may be implemented by an NRF in the network architecture shown in fig. 2, the mobility management function network element provided in the embodiment of the present application may be implemented by an AMF in the network architecture shown in fig. 2, and the user plane function network element related to the embodiment of the present application may be implemented by a UPF in the network architecture shown in fig. 2. For easier understanding, the following presents a simplified description of some functional network elements to which embodiments of the present application will mainly relate.

The mobility management function network element, for example, an MME in the 4G system, and an AMF in the 5G system, is not limited to this, and may be implemented by other network elements in other communication systems. Taking an example that the mobility management function network element is an AMF, the AMF is mainly responsible for interfacing with a radio, terminating a Radio Access Network (RAN) Control Plane (CP) interface, that is, an N2 interface, terminating a non-access-stratum (NAS) and NAS encryption and integrity protection, registration management, connection management, reachability management, mobility management, transferring a Session Management (SM) message between a User Equipment (UE) and an SMF, or notifying a mobility event of the UE.

The session management function network element, for example, the session management function network element 101, in the 5G system, for example, is an SMF, and in other communication systems, may also be implemented by other network elements. Taking the SMF as AN example, the SMF may provide session management functions such as session establishment, modification, and release, including a tunnel maintenance function between the UPF and AN Access Network (AN) node, Internet Protocol (IP) address allocation and management of the UE, Dynamic Host Control Protocol (DHCP), User Plane (UP) selection and control function, UPF diversion function configuration, terminating policy control function interface, charging, roaming function, or policy control related function.

The user plane function network element, for example, UPF in the 5G system, may also be implemented by other network elements in other communication systems. Taking the case that the user plane functional network element is the UPF, which is an entity for user plane data forwarding, as an external PDU session point for data network interconnection, and has functions of message routing and forwarding, message detection, user plane part policy execution, lawful interception, traffic usage reporting, or quality of service (QoS) processing, and the like.

The network function repository function network element, for example, the network function repository function network element 102, in the 5G system, for example, NRF, may also be implemented by other network elements in other communication systems. Taking the NRF as an example, the network function repository function network element may support functions such as a service discovery function, and maintaining NF configuration of an available Network Function (NF) instance. In the roaming scenario, the visited NRF (visited NRF) and the home NRF (home NRF, hNRF) are further divided. Based on network implementation, it is further classified as a Public Land Mobile Network (PLMN) level NRF, a shared slice NRF, or a slice-specific NRF. Wherein, the NRF of PLMN level can be understood as different NRFs can be used by different PLMNs; slice NRF is shared, it being understood that different network slices may share one NRF; a slice-specific NRF, it is understood that different network slices use different NRFs, respectively.

In addition, when introducing the network architecture shown in fig. 2, the concept of the service method is mentioned, and specifically, in the 5G system, it is currently considered that interaction between network elements of the control plane may be performed through a service-based method, and interaction between network elements of the user plane may be performed through a point-to-point method. For example, in a 5G system, NRF is a network element of a control plane, some service methods may be opened, and other devices may interact with NRF through these service methods. Referring to table 1, some service method illustrations open for NRF:

TABLE 1

The SMSF in table 1 is a short message service function (SMS function, SMSF), wherein the SMS is a short message service (short message service), and the BSF is a Binding Support Function (BSF).

As can be seen from table 1, NRF opens all service methods in table 1 to AMF and SMF, and opens NF register method, NF update method, and NF deregister method in NF management service to UPF, so UPF may send service request associated with UPF such as registration, update, or logout to NRF.

For example, in the network architecture shown in fig. 2, as can be seen from table 1, NRF opens a service method of NF status notify to AMF, SMF, PCF, NEF, NSSF, SMSF, and AUSF, and thus AMF, SMF, PCF, NEF, NSSF, SMSF, and AUSF can all communicate with NRF through the service method of NF status notify, but because NRF does not open a service method of NF status notify to UDM, UDM cannot communicate with NRF through the service method of NF status notify.

Fig. 3 is a schematic diagram of a network architecture of a local breakout roaming scenario. In the network architecture, the terminal equipment can roam, so that two areas of VPLMN and HPLMN are included. In VPLMN, NSSF, NEF, NRF, PCF, AF, AMF, SMF, and visited security edge protection proxy (vSEPP), these network elements may communicate with each other based on a service method, of course, two of them need to communicate, and one network element needs to open a corresponding service method to another network element, which is not limited to the example. In addition, the AMF and the terminal device may communicate through AN N1 interface, the AMF and the (R) AN may communicate through AN N2 interface, the SMF and the UPF may communicate through AN N4 interface, communication between the terminal device and the (R) AN may be enabled, the (R) AN and the UPF may communicate through AN N3 interface, and the UPF and the DN may communicate through AN N6 interface. In the HPLMN, the UDM, the NRF, the PCF, the AUSF, the NEF, and a home security edge protection proxy (hSEPP) may communicate with each other based on a service method, and certainly, two network elements among these network elements need to communicate, and it is necessary for one network element to open a corresponding service method to another network element, which is not limited to the example. The vSEPP and hSEPP may communicate over an N32 interface.

For example, the session management function network element 101 provided in this embodiment of the present application may be implemented by an SMF located in a VPLMN in the network architecture shown in fig. 3, the network function repository function network element 102 provided in this embodiment of the present application may be implemented by an NRF located in the VPLMN in the network architecture shown in fig. 3, the mobility management function network element provided in this embodiment of the present application may be implemented by an AMF located in the VPLMN in the network architecture shown in fig. 3, and the user plane function network element related to this embodiment of the present application may be implemented by a UPF located in the VPLMN in the network architecture shown in fig. 3. Of course, the embodiment of the present application is not limited, and the technical solution provided in the embodiment of the present application may be applied to VPLMN, as well as HPLMN, that is, each network element provided in the embodiment of the present application may also be a corresponding network element located in HPLMN.

Please refer to fig. 4, which is a schematic diagram of a network architecture in a home routing roaming scenario. In the network architecture, the terminal equipment can also roam, so that two areas of VPLMN and HPLMN are included. In VPLMN, NSSF, NEF, NRF, PCF, AMF, SMF, and vSEPP, these network elements may communicate with each other based on a service method, and certainly, two of these network elements need to communicate with each other, and it is necessary for one network element to open a corresponding service method to another network element, which is not limited to the example. In addition, the AMF and the terminal device may communicate through AN N1 interface, the AMF and the (R) AN may communicate through AN N2 interface, the SMF and the UPF may communicate through AN N4 interface, communication between the terminal device and the (R) AN may be enabled, the (R) AN and the UPF may communicate through AN N3 interface, and the UPF and the DN may communicate through AN N6 interface. In the HPLMN, the UDM, NRF, NSSF, SMF, AF, PCF, AUSF, NEF, and hSEPP may communicate with each other based on a service method, and certainly, when two network elements communicate with each other, one network element needs to open a corresponding service method to the other network element, which is not limited to this example. In addition, SMF may communicate with UPF over an N4 interface, UPF and DN may communicate over an N6 interface, UPF in VPLMN and UPF in HPLMN may communicate over an N9 interface, vSEPP and hSEPP may communicate over an N32 interface.

For example, the session management function network element 101 provided in this embodiment of the present application may be implemented by an SMF located in a VPLMN in the network architecture shown in fig. 4, the network function repository function network element 102 provided in this embodiment of the present application may be implemented by an NRF located in the VPLMN in the network architecture shown in fig. 4, the mobility management function network element provided in this embodiment of the present application may be implemented by an AMF located in the VPLMN in the network architecture shown in fig. 4, and the user plane function network element related to this embodiment of the present application may be implemented by a UPF located in the VPLMN in the network architecture shown in fig. 4. Of course, the embodiment of the present application is not limited, and the technical solution provided in the embodiment of the present application may be applied to VPLMN, as well as HPLMN, that is, each network element provided in the embodiment of the present application may also be a corresponding network element located in HPLMN.

Regarding the network architecture shown in fig. 3 and the network elements related to the network architecture shown in fig. 4, the network architecture shown in fig. 2 has already been introduced, and therefore will not be described in detail.

In fig. 2 to 4, the main function of (R) AN is to control the terminal device to access the mobile communication network by radio. The (R) AN is part of a mobile communication system. It implements a wireless access technology. (R) AN devices include, but are not limited to: in 5G, the Radio Network Controller (RNC), a Node B (NB), a Base Station Controller (BSC), a Base Transceiver Station (BTS), a home base station (e.g., home evolved node B or home node B, HNB), a Base Band Unit (BBU), a transmission point (TRP), a Transmission Point (TP), a mobile switching center (TP), and the like, and may further include a wireless fidelity (wifi) Access Point (AP), and the like.

The foregoing describes a system 100 for selecting a network element with a session management function according to an embodiment of the present application, and several network architectures that the system 100 may be applied to a 5G system, and the following continues to use the 5G system as an example to describe the technical background of the embodiment of the present application.

In the process of creating the PDU session, a process of selecting the SMF by the AMF and a process of selecting the UPF by the SMF are included. The flow of selecting SMF and selecting UPF in the existing 5G system architecture is detailed in the third generation partnership project (3 GPP) standard version 23.502-f 10. First, the flow of selecting SMF by AMF is described with reference to fig. 5.

S501, the AMF sends a request message to the NSSF, for example, the request message is called a first request message, the NSSF receives the first request message, where the first request message carries request parameters, and the request parameters include (S-NSSAI) single network slice selection establishment information (NSSAI) meeting a network slice selection establishment information (NSSAI) condition requested by the terminal device, and a PLMN identity number (ID), and indicate whether the first request message is applicable to a non-roaming scenario or a local offloading roaming scenario.

For example, the AMF may call a network slice selection acquisition (NSSF _ NSSelection _ Get) service method provided by the NSSF, and send a first request message to the NSSF.

S502, the NSSF selects a network slice according to the request parameter sent by the AMF, that is, the NSSF selects a network slice conforming to the request parameter sent by the AMF, and then, the NSSF determines and sends information of an NRF suitable for the network slice to the AMF, for example, the NSSF is a response (NSSF _ NSSelection _ Get response) for invoking network slice selection acquisition provided by the NSSF, and the service method sends information of an NRF suitable for the network slice to the AMF, for example, a message sent by the NSSF to the AMF is referred to as a first response message, that is, the first response message in fig. 5. Among them, a Network Slice Instance (NSI) ID of a network slice selected by the NSSF may be transmitted together as an option.

S503, the AMF sends the second request message to the NRF, and the NRF receives the second request message. The second request message is used to query the SMF that meets the parameter requirement, and the AMF is used to query the parameters of the SMF, that is, the parameters carried in the second request message include, for example, S-NSSAI, PLMN ID, DNN, and the like.

For example, the AMF may call an NF discovery Request (nrrf _ NFDiscovery _ Request) service method provided by the NRF to transmit the second Request message to the NRF.

S504, the NRF sends a Full Qualified Domain Name (FQDN) or an IP address of the SMF to the AMF, for example, if the NRF sends the FQDN or the IP address to the AMF by a response (NRF _ NFDiscovery _ Request response) service method that calls an NF discovery Request provided by the NRF, the AMF receives the FQDN or the IP address of the SMF. This is equivalent to the AMF obtaining the requested SMF information.

Of course, if the AMF knows the NRF information, S501 and S502 in the flow shown in fig. 5 may not be executed, and only S503 and S504 need to be executed, otherwise, S501 to S504 need to be executed.

The flow shown in fig. 5 describes the process of selecting SMF by AMF, and the flow of selecting UPF by SMF is described below, and the process of selecting UPF by SMF through NRF is described below, please refer to fig. 6.

Fig. 6 includes two processes, one is a process in which the SMF subscribes to information of the UPF from the NRF, and the other is a process in which the UPF transmits information of the UPF to the NRF.

Wherein, the process of subscribing the UPF information from the NRF by the SMF includes the following S601 and S602:

s601, the SMF sends a subscription request to the NRF, then the NRF receives the subscription request, the subscription request carries subscription parameters, and the subscription parameters are information of UPFs which the SMF is interested in, namely information of UPFs which the SMF needs to subscribe to. The subscription parameter includes, for example, a Data Network Name (DNN), an S-NSSAI or an SMF area identity (SMF area identity), and the like.

For example, the SMF may call an NF management NF status subscription (nrrf _ NFManagement _ nfstatuussubscript) service method provided by the NRF to initiate a subscription to the NRF, that is, send a subscription request.

S602, the NRF sends a notification message to the SMF, and the SMF receives the notification message, wherein the notification message carries the information of the UPF which currently accords with the subscription parameters. In fig. 6, the notification message in S602 is referred to as a first notification message.

For example, the NRF may call an NF management NF status notification (nrrf _ NFManagement _ nfstatunotify) service method provided by the NRF to transmit a notification message to the SMF.

For example, the information of the UPF carried by the first notification message may be the FQDN or IP address of the N4 interface of the UPF.

If there is no UPF meeting the subscription parameters currently, the NRF may not need to execute S602; or, the NRF performs S602, but in S602, the first notification message sent by the NRF to the SMF carries not information of a UPF that conforms to the subscription parameters, but notification information for notifying the SMF that there is no UPF that conforms to the subscription parameters currently.

The process of sending the information of the UPF to the NRF by the UPF includes the following steps S603 to S607, where the following steps S603 to S607 may also be understood as a process that occurs after a new UPF is deployed in the system:

and S603, deploying a new UPF to the system.

S604, an operation, administration, and maintenance (OAM) system configures identification information of the NRF on the UPF and configures attribute information for the UPF.

S605, the UPF sends a request message, for example, called a third request message, to the NRF, and the NRF receives the third request message, where the third request message carries a Network Function (NF) type of the UPF, an FQDN, or an IP address of an N4 interface, and attribute information configured for the UPF by the OAM in S604.

For example, the UPF may call an NF management NF registration (nfm _ NFManagement _ NFRegister) service method provided by the NRF to transmit a request message to the NRF.

S606, the OAM system registers the information of the UPF with the NRF.

For example, when a UPF is deployed to or deregistered from a system, the OAM system may write the information of the deployed or deregistered UPF into the SMF's local configuration. The SMF may select a UPF based on this information. In addition, the information of the UPF written in the local configuration of the SMF may also be updated, for example, the information of the UPF on the SMF may be updated by the OAM system at any time after the initial configuration.

S606 is an equivalent manner of S605, and one of the two manners may be selected, that is, S605 and S606 may be selected to be executed.

S607, if the information of the UPF conforms to the subscription parameter of the SMF, that is, the UPF conforms to the subscription request of the SMF, the NRF may send a notification message to the SMF, and the SMF receives the notification message, where the notification message carries the information of the UPF. For example, the information of the UPF carried by the notification message may be the FQDN or IP address of the N4 interface of the UPF. In fig. 6, the notification message in S607 is referred to as a second notification message.

For example, the NRF may call the nrrf _ NFManagement _ nfstatustnotify service method to send a second notification message to the SMF.

According to the flow shown in fig. 5, the AMF may select multiple SMFs, and according to the flow shown in fig. 6, the SMF may select multiple UPFs, so that when creating a PDU session, the AMF may select one SMF from the multiple SMFs to execute the current PDU session, and if the SMF has multiple optional UPFs, the SMF may also select one UPF from the multiple UPFs to execute the current PDU session.

As can be seen from the flow shown in fig. 6, when an SMF selects a UPF, an available UPF may not necessarily be selected, that is, the SMF selected by the AMF may not necessarily select an available UPF, so that the SMF selected by the AMF may be invalid, if the selected SMF is invalid, the AMF further needs to reselect the SMF, and the reselected SMF further needs to reselect a UPF, so that the efficiency of selecting the SMF is low, and a large delay is brought to creating a PDU session.

In view of this, according to the technical solution of the embodiment of the present application, by setting the state of the session management function network element 101, when selecting the session management function network element 101, the selection may be performed with reference to the state of the session management function network element 101, so as to ensure that the selected session management function network element 101 can select an available user plane function network element as much as possible, thereby improving the selection efficiency of the session management function network element 101, and also reducing the time delay for creating a session.

In the network architecture shown in any one of fig. 2 to 4, the network elements related to the embodiment of the present application are mainly: AMF, SMF, and NRF, although the embodiments of the present application also relate to UPF.

For convenience of description, in the following description of the embodiments of the present application, the solution provided in the embodiments of the present application is applied to a 5G system as an example, that is, in the following description, a mobility management function network element is an AMF network element, a session management function network element is an SMF network element, a network function repository function network element is an NRF network element, and a user plane function network element is an UPF network element are all used as examples. Further, the AMF network element is abbreviated as AMF, the SMF network element is abbreviated as SMF, the NRF network element is abbreviated as NRF, and the UPF network element is abbreviated as UPF. That is, AMFs described later in this embodiment may be replaced with a mobility management function network element, SMFs may be replaced with a session management function network element, NRFs may be replaced with a network function repository function network element, and UPFs may be replaced with a user plane function network element, for example, SMFs described later in this embodiment may be replaced with a session management function network element 101, and NRFs may be replaced with a network function repository function network element 102.

The following describes a method for selecting a network element with a session management function according to an embodiment of the present application with reference to the accompanying drawings.

Referring to fig. 7, in the following description, taking the application of the method in the scenario shown in fig. 2, fig. 3 or fig. 4 as an example, the method may be executed by the session management function network element 101 and the network function repository function network element 102 included in the system 100 for selecting a session management function network element provided in the embodiment shown in fig. 1, that is, SMF and NRF described below, and of course, in the implementation of the method, a mobility management function network element and a user plane function network element, that is, AMF and UPF described below are also involved. In addition, the embodiment of the present application may roughly include two processes, a first process is referred to as a state synchronization process, for example, and may occur before the PDU session is created or in a process of creating the PDU session, and a second process is referred to as a process of selecting an SMF, for example, and may occur in a process of creating the PDU session.

First, describing S701 to S706, these steps belong to the status synchronization process as described above, and occur before or in the process of creating the PDU session.

S701, configuring a selection policy table for the SMF and the AMF.

And when the SMF selects the UPF, the UPF meeting the screening condition needs to be selected, wherein when the SMF selects the UPF, the selection can be carried out according to one screening condition or a plurality of screening conditions. For a screening condition, the screening condition may include at least one parameter, for example, the screening condition may include DNN, or the screening condition may include S-NSSAI, or the screening condition may include DNN and S-NSSAI, and of course, in addition to DNN and/or S-NSSAI, the screening condition may include other parameters, for example, some attribute parameters of UPF, and the like, or the screening condition may not include DNN and S-NSSAI, but include other parameters, which is not limited in the embodiments of the present application. If the SMF is selected based on multiple screening conditions, the parameters included in different screening conditions may all be the same, but the values of the parameters are different. For example, there are two screening conditions, where the two screening conditions both include DNN as a parameter, but DNN values in the two screening conditions are different; alternatively, the different screening conditions may comprise different parameters, for example, one screening condition comprises DNN, and the other screening condition comprises DNN and S-NSSAI, without limitation. The screening conditions used by the SMF when selecting the UPF may be how many screening conditions are configured in the SMF in advance, and parameters corresponding to each screening condition, etc., may all depend on the application scenario and the configuration of the operator. Wherein, if only one screening condition is configured, it indicates that the SMF can support UPFs of one class of characteristics, and if multiple screening conditions are configured, it indicates that the SMF can support UPFs of multiple classes of characteristics. Since the selection of SMF by AMF is also subsequently involved, the screening conditions may also be preconfigured in AMF, wherein the screening conditions configured in AMF may be the same as or different from the screening conditions configured in SMF.

In the embodiment of the present application, for example, the screening conditions may be stored in a table, which may be referred to as a selection policy table, and at least one screening condition may be included in the selection policy table, so that the screening conditions may be configured by configuring the selection policy table for the SMF and the AMF.

The SMF needs to obtain the information of the UPF to determine whether the UPF meeting the screening condition exists, so that whether the UPF meets the screening condition is judged according to the information of the UPF. The UPF, where the SMF can obtain information, may be understood as a UPF associated with the SMF, or hereinafter, an SMF associated with a UPF, and may also be described as an SMF to which the UPF belongs. The following S702-S704 describe one way for the SMF to obtain information for the UPF.

S702, a UPF is deployed to the system, and configuration is completed.

After one UPF is deployed to the system, the UPF may be configured by the OAM.

S703, the UPF sends the UPF instance information change message to the SMF through the N4 interface, and the SMF receives the UPF instance information change message through the N4 interface.

The UPF instance information change message is only a name, and does not limit the message itself, and the message is just for the UPF to send the attribute information of the UPF to the SMF, and the message for achieving the purpose may be the UPF instance information change message. In this embodiment, the attribute information of the UPF is also referred to as UPF information, and includes at least one of a UPF dynamic load, a DNN, UE location information, an S-NSSAI, a PDU session type, and the like, for example, and may also include other information.

In the embodiment shown in fig. 7, taking the example that one UPF is deployed in the system, in practical applications, there may be at least one UPF deployed in the system, and at least one UPF may all send information of the UPF to the SMF, so that the SMF may receive information of the at least one UPF from the at least one UPF, where one UPF sends only information of the UPF to the SMF, and does not send information of another UPF, and therefore, the SMF receives information of the one UPF from one UPF.

That is, the UPF may actively send information of the UPF to the SMF after being deployed to the system, and then the SMF may obtain information of at least one UPF if at least one UPF sends information of the UPF to the SMF.

The embodiment of the application takes the case that a new UPF is deployed to trigger the UPF to send the information of the UPF to the SMF, and may actually be applied to a scene that needs to update the information of the UPF, such as UPF update, UPF logout, or UPF load state change, and if the information of the UPF is updated, the UPF may also send the information of the UPF. Under these scenarios, only the trigger condition is changed, and the processing flow is not changed.

S704, the SMF classifies and stores the information of the UPF into a UPF state parameter table.

After obtaining the information of the UPF, the SMF may directly store the information, or may classify the information of the UPF, for example, the information of the UPF having the same parameter is classified into one class, for example, the SMF may set a UPF state parameter table, and store the information of the UPF in the UPF state parameter table in a classified manner. No matter what storage method is adopted by the SMF, the information of the UPF stored by the SMF refers to information of an available UPF, and the availability here refers to that the UPF can normally provide services to the outside. In addition, the SMF may also monitor the status of the UPF at any time, and if the status of the UPF in the UPF status parameter table changes, for example, goes down, or goes down suddenly, the SMF may delete the information of the UPF from the UPF status parameter table, so as to ensure that all the information of the UPF stored in the UPF status parameter table is available. The SMF may know whether the UPF is offline through a deregistration process, and regarding the downtime of the UPF, a detection mechanism, such as a heartbeat detection mechanism, may be maintained between the SMF and the UPF, and if the SMF cannot receive heartbeats sent by the UPF, the UPF may be determined to be down, or the SMF may further determine whether the state of the UPF is changed through a notification of the NRF, so as to determine whether the UPF is available. The UPF state parameter table may include at least one UPF state, and one UPF state may correspond to information of at least one UPF, that is, at least one UPF may satisfy one UPF state. For example, please refer to table 2, which is an example of a UPF status parameter table:

TABLE 2

UPF status (instance) ID	DNN	S-NSSAI
			1	DNN_1	S-NSSAI_1，S-NSSAI_2
2	DNN_1	S-NSSAI_1
			3	DNN_2	S-NSSAI_3

In table 2, one UPF state represents a class of UPF, and a class of UPF will have some of the same attributes, UPF state ID, i.e., a number is set for the UPF state, and tables 2, 1, 2, and 3 represent three classes of UPF states, and the parameters in the second column and the parameters in the third column are the parameters corresponding to the UPF state, i.e., the parameters satisfied by a class of UPF. Of course, table 2 exemplifies the setting of numbers for UPF states, and in practical applications, no numbers may be set for UPF states, that is, the first column in table 2 may be removed, and then a row in table 2 after removing the first column indicates a UPF state.

S705, SMF decision is made, and whether the SMF is available under the screening condition is carried out.

The SMF determines whether the SMF is available under the screening conditions, i.e., determines whether there is a UPF available under the screening conditions, or whether there is a UPF that meets the screening conditions.

For example, if the screening condition is specifically one, which may be referred to as a first screening condition, the SMF determines whether there is a UPF that meets the screening condition, specifically, whether there is a UPF that meets the first screening condition. Alternatively, the screening conditions are more than one, for example, two screening conditions are referred to as a second screening condition and a third screening condition, and then the SMF determines whether there is a UPF meeting the screening conditions, specifically, determines whether there is a UPF meeting the second screening condition, and determines whether there is a UPF meeting the third screening condition. If there are more screening conditions, the processing method is similar, and will not be described in detail.

Referring to table 3, an example of a pre-configured selection policy table in SMF may be:

TABLE 3

Policy (Policy) ID	Parameter(s)
		1	DNN:DNN_1,S-NSSAI:S-NSSAI_1
2	DNN:DNN_3

The strategy in table 3 can be understood as a screening condition, and it can be seen that the selection strategy table shown in table 3 includes two screening conditions. The policy ID is identification information set for the filtering condition. The identification information may be a number, and the like, and the embodiment of the present application is not limited as long as different screening conditions can be distinguished. Tables 3, 1 and 2, represent two screening conditions, and the parameters in the second column are the corresponding parameters of the screening conditions. The identification information of the screening condition may also be preset, that is, a correspondence between the parameter information corresponding to the screening condition and the identification information of the screening condition is preset in the SMF. In the example of table 3, the SMF may determine whether there is a UPF that meets both of these screening criteria, respectively. In addition, in table 3, the example is that the identification information is set for the screening condition, and in practical application, the selection policy table shown in table 3 may be changed to the selection policy table shown in table 4 without setting the identification information for the screening condition:

TABLE 4

Screening conditions
	DNN:DNN_1,S-NSSAI:S-NSSAI_1
DNN:DNN_3

One row in table 4 represents one screening condition, and table 4 includes two screening conditions.

In tables 3 and 4, each of the screening conditions corresponds to a specific parameter, and in addition, there is a case where one of the screening conditions may not correspond to any parameter, that is, the parameter corresponding to the screening condition is empty, which means that the UPFs do not need to be screened, and if the UPFs that can be found are all the UPFs that satisfy the screening condition, or it can be understood that the screening condition is used to screen all the UPFs, and of course, "all" herein refers to all the available UPFs that can be found by the SMF. For example, in the case that the screening condition is specifically the first screening condition, the first screening condition may correspond to some parameters, or the parameters corresponding to the first screening condition may also be null. And if the parameter corresponding to the first screening condition is null, indicating that the first screening condition is used for screening all available UPFs. For another example, in the case that the screening condition is specifically the second screening condition and the third screening condition, both the second screening condition and the third screening condition may correspond to corresponding parameters; alternatively, at least one of the second screening condition and the third screening condition may be null. If at least one of the second screening condition and the third screening condition is empty, it indicates that the at least one screening condition is for screening all available UPFs, or, as understood, indicates that each of the at least one screening condition is for screening all available UPFs.

After obtaining the UPF information, the SMF may directly determine whether there is UPF information that meets the screening condition according to the screening condition included in the selection policy table. For example, the SMF may obtain information of a plurality of UPFs, and the SMF does not classify and store the information of the UPFs during storage, the SMF may respectively determine the information of each UPF to determine whether the information of each UPF meets the screening condition. The information of the UPF obtained by the SMF, or the information of the UPF that the SMF takes to determine whether the UPF meets the screening condition, must be the information of the available UPF described above. In addition, there may be multiple screening conditions that the SMF uses to determine, and then the SMF may determine, for each obtained UPF information, whether the UPF information meets each of the multiple screening conditions. The information of one UPF conforms to one screening condition, which indicates that the UPF corresponding to the information of the UPF conforms to the one screening condition.

Or, if the SMF sets the UPF state parameter table, the SMF may query the UPF state parameter table according to each filtering condition to determine whether there is a UPF meeting the filtering condition.

For example, the selection policy table preset in the SMF may refer to table 3, the information of the UPF obtained by the SMF is stored in the UPF state parameter table, and the UPF state parameter table may refer to table 2. Policy ID in table 3 is 1, UPF Instance ID 1 and UPF Instance ID 2 are matched in table 2, Policy ID 2 in table 3 is not matched in table 2, i.e., no UPF is temporarily matched with Policy ID 2 in table 3.

The SMF may determine that the SMF is an available state under the first screening condition (Policy ID ═ 1) in the selection Policy table shown in table 3, and that the SMF is an unavailable state under the second screening condition (Policy ID ═ 2) in the selection Policy table shown in table 3.

It can be seen that, in the embodiment of the present application, since one or more screening conditions may be preset in the SMF, if multiple screening conditions are set, the same SMF may exhibit multiple characteristics, and the application range of the SMF is expanded.

As described above, it can be known from the description that if the SMF acquires the information of at least one UPF, the SMF may determine whether there is a UPF that meets the screening condition in the at least one UPF according to the information of the at least one UPF. However, it is also possible that the SMF cannot acquire information of the UPF, for example, the UPF may actively send information of the UPF to the SMF, but the SMF does not receive information of the UPF sent by the UPF temporarily, and in these cases, the SMF cannot acquire information of the UPF; or, in another possibility, the information of the UPF acquired by the SMF is not available; or the SMF determines that all the UPFs previously stored in the UPF state parameter table are changed to unusable UPFs, that is, it is considered that the above-described cases are all cases where the SMF acquires information of usable UPFs, and in this case, the SMF acquires information of UPFs but the UPFs are unusable. The unusable condition means that the UPF is not in accordance with the screening condition, but cannot work normally, for example, the UPF is down or down. Then, if the SMF does not acquire information of the UPF or the SMF does not acquire information of an available UPF, the SMF may directly determine that there is no UPF that meets the screening condition, that is, it may be determined that the SMF is not available under the screening condition.

If it is determined that there is a UPF that meets the screening conditions, the SMF may optionally set the status of the SMF to an available status under the screening conditions.

As described above, the screening condition may be one or more, and if the screening condition is more than one, the SMF also determines whether there is a UPF meeting each of the screening conditions, and if the screening condition is more than one, the SMF may set the state of the SMF for each of the screening conditions.

For example, if the screening condition is specifically the first screening condition, if there is a UPF meeting the first screening condition, the SMF may set the state of the SMF to be an available state under the first screening condition.

Or, the screening condition is specifically the second screening condition and the third screening condition, and if there is a UPF meeting the second screening condition, the SMF may set the state of the SMF to be the available state under the second screening condition, or if there is a UPF meeting the third screening condition, the SMF may set the state of the SMF to be the available state under the third screening condition.

It can be seen that the state of the SMF is related to the filtering condition, and then the SMF, if storing the state of the SMF, may store the state of the SMF in correspondence with the filtering condition. For example, if the screening condition is shown in table 3, a column may be added to table 3 to store the state of the SMF, and referring to table 5, the SMF may store table 5, and table 5 indicates which screening conditions the SMF is available under.

TABLE 5

Policy (Policy) ID	Status of state	Parameter(s)
			1	Can be used	DNN:DNN_1,S-NSSAI:S-NSSAI_1
2		DNN:DNN_3

The second column in table 5 indicates the state of the SMF, and table 5 follows the example in which tables 2 and 3 are combined, and in this example, the SMF is available under the first screening condition (Policy ID ═ 1) and is not available under the second screening condition (Policy ID ═ 2), and therefore the state of the SMF corresponding to the first screening condition (Policy ID ═ 1) in table 5 is "available". Of course, the expression "available" here is merely an example, for example, the SMF may also represent the state of the SMF by 1 bit, and if the bit takes "1", it represents that the SMF is an available state, and the embodiment of the present application does not limit the expression of the state of the SMF.

Or for example, if the screening condition is shown in table 4, a column may be added to table 4 to store the state of the SMF, and this table refers to table 6, the SMF may store table 6, and table 6 indicates which screening conditions the SMF is available under.

TABLE 6

Status of state	Screening conditions
		Can be used	DNN:DNN_1,S-NSSAI:S-NSSAI_1
	DNN:DNN_3

Table 6 shows the state of the SMF in the first column, and table 6 exemplifies that the selection condition indicated by the SMF in the first row of table 6 is the available state, and therefore the state of the SMF corresponding to the first selection condition (the first row of table 6) in table 6 is "available".

S706, if there is a UPF meeting the filtering condition, and the SMF sends the first status information of the SMF to the NRF, the NRF receives the first status information of the SMF from the SMF, where the first status information of the SMF is used to indicate that the SMF is available under the filtering condition, and the first status information is used to select the SMF.

For example, the SMF may call a NF management NF upgrade (nrrf _ NFManagement _ NFUpdate) service method provided by the NRF to transmit first state information of the SMF to the NRF.

It is introduced that, in this document, the state information indicating that the SMF is available is referred to as the first state information of the SMF, for example, in table 5, the state information indicating that the SMF is available under the first filtering condition (Policy ID ═ 1) may be referred to as the first state information of the SMF.

That is, although the SMF determines whether there is a UPF that meets the filtering condition, there may be a UPF that meets the filtering condition, or there may not be a UPF that meets the filtering condition, that is, the state of the SMF under the filtering condition may be an available state or an unavailable state, in this embodiment, the SMF may send only the first state information of the SMF to the NRF, that is, the SMF sends only the information that the SMF is in the available state to the NRF, so that the NRF may store only the SMF in the available state. If the screening condition is multiple, the SMF may send only the information that the SMF is in the available state to the NRF, for example, for table 5, the SMF may send only the state information that the SMF is in the available state under the first screening condition (Policy ID ═ 1) to the NRF, and for the state information that the SMF is in the unavailable state under the second screening condition (Policy ID ═ 2), the SMF may not send to the NRF. In this case, the NRF may store only information of the SMFs in the available state, and for example, the NRF may store a correspondence between the filtering condition and the state of the SMF, and is an SMF in the available state as long as the NRF stores the correspondence. For example, the NRF may store information of the first row of table 6. Alternatively, the NRF may store the correspondence among the identification information of the filtering condition, and the state of the SMF, and similarly, the NRF may be an SMF in a usable state as long as the NRF stores the correspondence. For example, the NRF may store information of the first row of table 5.

Alternatively, the SMF may only send the second status information of the SMF to the NRF, and the second status information of the SMF may be used to indicate that the SMF is not available under the filtering condition, that is, the SMF only sends the information that the SMF is in the unavailable state to the NRF, so that the NRF may only store the SMF in the unavailable state. If the screening condition is multiple, the SMF may send only the information that the SMF is in the unavailable state to the NRF, for example, for table 5, the SMF may send only the state information that the SMF is in the unavailable state under the second screening condition (Policy ID ═ 2) to the NRF, and for the state information that the SMF is in the available state under the first screening condition (Policy ID ═ 1), the SMF may not send to the NRF. In this case, the NRF may store only information of the SMF in the packet available state, and for example, the NRF may store a correspondence relationship between the filtering condition and the state of the SMF, and is an SMF in the unavailable state as long as the NRF stores the correspondence relationship. For example, the NRF may store a correspondence relationship between the filtering condition and the state of the SMF, or the NRF may store a correspondence relationship between identification information of the filtering condition, and the state of the SMF, and similarly, the NRF is an SMF in an unavailable state as long as the NRF stores the correspondence relationship.

In the embodiment of the present application, the first state information and the second state information of the SMF are collectively referred to as state information of the SMF, that is, the state information of one SMF may include the first state information or the second state information of the SMF. In the foregoing, it is described that the first state information may have different implementation manners, and different implementation manners may implement different indication manners, and then similarly, the state information of the SMF also has different implementation manners, and different implementation manners may implement different indication manners.

For example, the status information of the SMF includes information indicating that the SMF is available under the screening condition, or includes information indicating that the SMF is not available under the screening condition. This way of indicating the state information of the SMF can be considered as an implicit way of indicating. That is, although the state information of the SMF directly indicates whether the SMF is available under the screening condition, it implicitly indicates whether the SMF has a UPF that satisfies the screening condition, that is, indicates whether the SMF has an available UPF by indicating the state of the SMF.

As another example, the state information of the SMF includes information indicating that the SMF has a UPF that satisfies the filtering condition, and this indication manner of the state information of the SMF may be regarded as an explicit indication manner. That is, the state information of the SMF directly indicates whether the SMF has a UPF that satisfies the screening condition, which is simple and direct.

As to what indication manner is used by the state information of the SMF, the state information may be predefined by a protocol, or may be determined by negotiation between network elements, and the like, which is not limited specifically. It can be seen that, in the foregoing, the state information of the SMF is mainly indicated by adopting an implicit indication manner, and in the following, the state information of the SMF is also continuously indicated by adopting an implicit indication manner.

For an SMF, the state of the SMF under one screening condition may be changed, for example, an SMF, and at one moment, there may be a UPF meeting the first screening condition, at this moment, the SMF is in the available state under the first screening condition, but at the next moment, there may be no UPF meeting the first screening condition, for example, a UPF meeting the first screening condition may be failed, etc., at this moment, the SMF is changed to the unavailable state under the first screening condition. Then, for the case where the NRF stores only SMFs in the available state, if the SMF is a state in which the SMF is transmitted to the NRF for the first time, the SMF may transmit only the first state information of the SMF, that is, only information that the SMF is in the available state, to the NRF, without transmitting information that the SMF is in the unavailable state. For example, if the SMF determines that the SMF is in the available state under the second screening condition and in the unavailable state under the third screening condition, the SMF may transmit only the first status information that the SMF is in the available state under the second screening condition to the NRF, and may not transmit the information that the SMF is in the unavailable state under the third screening condition to the NRF. However, if the SMF is not the state in which the SMF is first sent to the NRF, the SMF may be sent to the NRF regardless of whether the state of the SMF is the available state or the unavailable state, so that the NRF can update the state of the SMF in time.

For example, if the SMF does not initially send status information to the NRF, then if the SMF determines that there is no UPF that meets the filtering condition, the status of the SMF is an unavailable status under the filtering condition, the SMF may set the status of the SMF to be an unavailable status under the filtering condition, the SMF may send second status information of the SMF to the NRF, and the second status information of the SMF may be used to indicate that the SMF is unavailable under the filtering condition. It can be understood that, in the embodiment of the present application, the state information of the SMF includes first state information and second state information of the SMF.

In this embodiment, the status information of the SMF may include parameter information corresponding to the filtering condition and include indication information indicating whether the SMF is available under the filtering condition, and the NRF may store the parameter information corresponding to the filtering condition and include indication information indicating whether the SMF is available under the filtering condition, for example, the first status information of the SMF includes the parameter information corresponding to the filtering condition and includes indication information indicating that the SMF is available under the filtering condition, and the second status information of the SMF includes the parameter information corresponding to the filtering condition and includes indication information indicating that the SMF is not available under the filtering condition. Alternatively, the status information of the SMF may include parameter information corresponding to the screening condition, identification information of the screening condition, and indication information indicating whether the SMF is available under the screening condition, and the NRF stores the parameter information corresponding to the screening condition, the identification information of the screening condition, and the indication information indicating whether the SMF is available under the screening condition, for example, the first status information of the SMF includes the parameter information corresponding to the screening condition, the identification information of the screening condition, and the indication information indicating that the SMF is available under the screening condition, and the second status information of the SMF includes the parameter information corresponding to the screening condition, the identification information of the screening condition, and the indication information indicating that the SMF is not available under the screening condition. Or the status information of the SMF may include identification information of the filtering condition and indication information indicating whether the SMF is available under the filtering condition, the NRF stores the identification information which may be the filtering condition and includes indication information indicating whether the SMF is available under the filtering condition, for example, the first status information of the SMF includes the identification information of the filtering condition and includes indication information indicating that the SMF is available under the filtering condition, and the second status information of the SMF includes the identification information of the filtering condition and includes indication information indicating that the SMF is not available under the filtering condition, in this case, the status information of the SMF may not include parameter information corresponding to the filtering condition, and the SMF transmits the status information of the SMF to the NRF in a smaller amount of information.

Or, as a special example, if the NRF only stores information of an available SMF, and if a subsequent SMF becomes unavailable under the filtering condition, the SMF sends a deletion indication to the NRF, where the deletion indication indicates the NRF to delete the information of the SMF under the filtering condition. Then, the status information of the SMF may also include parameter information corresponding to the filtering condition and identification information of the SMF, or the status information of the SMF includes identification information of the filtering condition and identification information of the SMF, that is, because the SMF sends to the NRF all available SMF information, the status information sent by the SMF to the NRF may not include indication information for indicating whether the SMF is available under the filtering condition, and the NRF may know that the SMF is an available SMF under the corresponding filtering condition as long as it receives the status information of the SMF. If the status information of the SMF includes indication information for indicating whether the SMF is available under the screening condition, a field for carrying the indication information needs to be added, and if the status information of the SMF does not include indication information for indicating whether the SMF is available under the screening condition, the field for carrying the indication information does not need to be added, which facilitates compatibility with the existing message format.

Or, as another specific example, if the NRF only stores the information of the unavailable SMF, and if the subsequent SMF becomes available under the filtering condition, the SMF sends to the NRF a deletion indication, where the deletion indication indicates the NRF to delete the information of the SMF under the filtering condition. Then, the status information of the SMF may also include parameter information corresponding to the screening condition and identification information of the SMF, or the status information of the SMF includes identification information of the screening condition and identification information of the SMF, that is, because the SMF sends to the NRF information of SMFs that are all unavailable, the status information sent by the SMF to the NRF may not include indication information for indicating whether the SMF is available under the screening condition, and the NRF may know that the SMF is an unavailable SMF under the corresponding screening condition as long as the NRF receives the status information of the SMF. If the status information of the SMF includes indication information for indicating whether the SMF is available under the screening condition, a field for carrying the indication information needs to be added, and if the status information of the SMF does not include indication information for indicating whether the SMF is available under the screening condition, the field for carrying the indication information does not need to be added, which facilitates compatibility with the existing message format.

However, in the following description, it is mainly exemplified that the status information of the SMF includes indication information for indicating whether the SMF is available under the screening condition.

For example, the selection policy table is shown in table 3, and if the SMF determines that the SMF is available under the first screening condition included in the selection policy table shown in table 3 and is unavailable under the second screening condition included in the selection policy table shown in table 3, a column may be added to table 3 for storing the state of the SMF, and referring to table 7, the SMF may store table 7, and table 7 indicates the screening conditions and the screening conditions under which the SMF is available.

TABLE 7

Policy (Policy) ID	Status of state	Parameter(s)
			1	Can be used	DNN:DNN_1,S-NSSAI:S-NSSAI_1
2	Is not available	DNN:DNN_3

The second column of table 7 shows the state of SMF. Of course, the expressions "available" and "unavailable" are only examples, for example, the SMF may also represent the state of the SMF by 1 bit, if the bit takes "1" to represent that the SMF is in the available state, and if the bit takes "0" to represent that the SMF is in the unavailable state, and the embodiment of the present application does not limit the expression of the state of the SMF. The first row of table 7 may be regarded as a first status message of the SMF, and the second row may be regarded as a second status message of the SMF, where the first status message and the second status message are both exemplified by identification messages including parameter messages corresponding to the filtering conditions and the filtering conditions, and if the status messages do not include parameter messages corresponding to the filtering conditions, for example, the first status message and the second status message include identification messages corresponding to the filtering conditions, the third column of table 7 may be omitted. If the SMF transmits the status information to the NRF for the first time, only the information of the first row in table 7 may be transmitted, and if the SMF does not transmit the status information to the NRF for the first time, all the information in table 7 may be transmitted.

Or for example, the selection policy table is shown in table 4, and if the SMF determines that the SMF is in the available state under the first screening condition included in the selection policy table shown in table 4 and is in the unavailable state under the second screening condition included in the selection policy table shown in table 4, a column may be added to table 4 for storing the state of the SMF, and referring to table 8, the SMF may store table 8, and table 8 indicates that the SMF is available under which screening condition and is unavailable under which screening condition.

TABLE 8

Status of state	Screening conditions
		Can be used	DNN:DNN_1,S-NSSAI:S-NSSAI_1
Is not available	DNN:DNN_3

In table 8, the first column indicates the state of the SMF, and table 8 exemplifies that the filtering condition indicated by the SMF on the first row of table 8 is the available state and the filtering condition indicated by the SMF on the second row of table 8 is the unavailable state, so in table 8, the state of the SMF corresponding to the first filtering condition (the first row of table 8) is "available" and the state of the SMF corresponding to the second filtering condition (the second row of table 8) is "unavailable". The first row of table 8 may be regarded as a first status information of the SMF, and the second row may be regarded as a second status information of the SMF, where the first status information and the second status information both take parameter information corresponding to the screening condition as an example, if the status information includes identification information of the screening condition, for example, the first status information and the second status information both include identification information corresponding to the screening condition, then the second column in table 8 may be replaced with the identification information of the screening condition, for example, the first column in table 7. If the SMF transmits the status information to the NRF for the first time, only the information of the first row in table 8 may be transmitted, and if the SMF does not transmit the status information to the NRF for the first time, all the information in table 8 may be transmitted.

Alternatively, in the case where the NRF stores only the information of the SMFs in the available states, if the SMF does not transmit the state information to the NRF for the first time, if the SMF determines that there is no UPF that meets the filtering condition, the SMF may not necessarily transmit the second state information of the SMF to the NRF, but may transmit a deletion instruction to the NRF, the deletion instruction being used to indicate the NRF, and the information of the SMF may be deleted from the information of the SMF that is available under the filtering condition. For example, if the first SMF initially has an available UPF under the first filtering condition, the first SMF is in an available state under the first filtering condition, and the first SMF sends the first state information that the SMF is in the available state under the first filtering condition to the NRF, and the NRF stores the first state information. For example, the NRF may store the corresponding relationship between the filtering condition and the SMF in the available state, and the NRF may store at least one filtering condition, where each filtering condition may correspond to information of at least one SMF, and the SMF corresponding to each filtering condition is the SMF available under the filtering condition. Then, if the first SMF subsequently has no available UPF under the first filtering condition, and the first SMF becomes unavailable under the first filtering condition, the first SMF may send a deletion instruction to the NRF, where the deletion instruction is used to instruct the NRF to delete the information of the first SMF corresponding to the first filtering condition, and after receiving the deletion instruction, the NRF may delete the information of the first SMF from the information of the SMF corresponding to the first filtering condition, and for the NRF, the first SMF is no longer an SMF in an available state under the first filtering condition.

Similarly, for the case where the NRF stores only the information of the SMF in the unavailable state, if the SMF does not transmit the state information to the NRF for the first time, if the SMF determines that there is a UPF that meets the filtering condition, the SMF may not necessarily transmit the first state information of the SMF to the NRF, but may transmit a deletion instruction to the NRF, the deletion instruction being used to indicate the NRF, and the information of the SMF is deleted from the information of the SMF that is unavailable under the filtering condition.

As described above, the NRF stores only the information of the SMF in the available state, and in the embodiment of the present application, the NRF may also store the information of the SMF in the unavailable state, that is, the NRF stores the information of the SMF in the available state and the information of the SMF in the unavailable state, so that the SMF can send the first state information and the second state information to the NRF for the NRF to store whether the SMF sends the state information of the SMF to the NRF for the first time or sends the state information of the SMF to the NRF for the subsequent time.

In addition, the screening condition may be one or more, and if the screening condition is the first screening condition, the SMF may send the status information of the SMF to the NRF, and the status information of the SMF indicates whether the SMF is available under the first screening condition. Or, the filtering condition is specifically the second filtering condition and the second filtering condition, the SMF may be considered to send a bar status message of the SMF to the NRF, where the status message indicates whether the SMF is available under the second filtering condition and indicates whether the SMF is available under the third filtering condition; alternatively, it may be considered that the SMF sends two bar status messages of the SMF to the NRF, one of which indicates whether the SMF is available under the second filtering condition, and the other of which indicates whether the SMF is available under the third filtering condition. Of course, if the SMF sends the first state information of the SMF to the NRF, the manner is similar, and details are not repeated.

As described in S701 to S706, these several steps belong to the status synchronization process included in the embodiment of the present application, and occur before the PDU session is created or in the process of creating the PDU session. S707 to S708 are described below, and these steps belong to the process of selecting an SMF included in the embodiment of the present application, and occur in the process of creating a PDU session.

S707, the AMF sends a request message to the NRF, and the NRF receives the request message from the AMF, where the request message is used to request to obtain information of the SMF meeting the fourth filtering condition.

For example, the AMF may call the nrrf _ NFDiscovery _ Request service method of the NRF to query the SMF satisfying the fourth filtering condition, that is, the AMF may call the nrrf _ NFDiscovery _ Request service method of the NRF to send the Request message to the NRF.

The filtering conditions used by the AMF to select the SMF and the filtering conditions used by the SMF to select the UPF may be the same concept, that is, as described above, the filtering conditions are also preconfigured in the AMF in addition to the filtering conditions preconfigured in the SMF. Or only the SMF is configured with the screening condition, and the SMF sends the configured screening condition to the AMF, or only the AMF is configured with the screening condition, and the AMF sends the configured screening condition to the SMF. For example, the fourth screening condition may be the first screening condition described above, or may be the second screening condition or the third screening condition described above, or may be different from the first screening condition, the second screening condition, and the third screening condition described above.

The AMF sends a request message to the NRF, wherein the request message is used for requesting to obtain information of the SMF meeting a fourth screening condition, and the SMF meeting the fourth screening condition can mean that the SMF meets the fourth screening condition; alternatively, an SMF that satisfies the fourth screening condition may also mean that the SMF satisfies the fourth screening condition and that the SMF has a UPF that satisfies the fourth screening condition.

The form of the filtering condition stored in the AMF, the SMF, and the NRF may be corresponding, for example, the AMF, the SMF, and the NRF all store parameter information corresponding to the filtering condition, of course, the AMF and the SMF store parameter information corresponding to the filtering condition, and the NRF stores a corresponding relationship between the parameter information corresponding to the filtering condition and the state information of the SMF. For another example, the AMF, the SMF, and the NRF all store identification information of the filtering condition, and of course, the AMF and the SMF store a correspondence between parameter information corresponding to the filtering condition and identification information of the filtering condition, the NRF store a correspondence between identification information of the filtering condition and status information of the SMF, or the NRF store a correspondence between identification information of the filtering condition, parameter information corresponding to the filtering condition, and status information of the SMF.

If the NRF stores the correspondence between the parameter information corresponding to the screening condition and the state information of the SMF, the request message sent by the AMF may carry the parameter information corresponding to the fourth screening condition, and the NRF may directly specify the condition that the AMF needs to query by this way. Or, if the NRF stores the correspondence between the identifier of the screening condition and the status information of the SMF, or stores the correspondence between the identifier of the screening condition, the parameter information corresponding to the screening condition, and the status information of the SMF, the request message sent by the AMF may also carry the identifier of the fourth screening condition without carrying the parameter information corresponding to the fourth screening condition, which may reduce the amount of information exchanged between the AMF and the NRF and save transmission resources.

After receiving the request message sent by the AMF, the NRF may determine whether there is an available SMF meeting the fourth filtering condition according to status information of at least one SMF, where the status information of the at least one SMF is used to indicate whether the at least one SMF is in an available state under the fourth filtering condition.

The NRF may store the status information of at least one SMF, wherein the status information of at least one SMF may be from at least one SMF, and the NRF may obtain the status information of the SMF according to the manner of obtaining the status information of the SMF, and the content of the status information of the SMF, etc. all refer to the above description.

In the foregoing, different implementations of the state information of the SMF are introduced, and specifically, if the state information of the SMF is implicitly indicated, for an SMF, the state information of the SMF may include information indicating that the SMF is an available SMF satisfying the fourth filtering condition, or information indicating that the SMF is an unavailable SMF satisfying the fourth filtering condition; or, if the status information of the SMF is indicated by display, the status information of the SMF may include, for one SMF, information indicating that the SMF has a UPF that satisfies the fourth filtering condition, or information indicating that the SMF does not have a UPF that satisfies the fourth filtering condition. Herein, "an available SMF satisfying the fourth screening condition" may also be understood as an SMF available under the fourth screening condition, where "available" refers to whether there is a UPF satisfying the fourth screening condition. The specific related contents have been introduced in the foregoing, and are not described in detail.

If the request message carries parameter information corresponding to the fourth screening condition, the SMF queries whether there is an available SMF satisfying the fourth screening condition according to the parameter information corresponding to the fourth screening condition, and if the request message carries identification information of the fourth screening condition, the SMF queries whether there is an available SMF satisfying the fourth screening condition according to the identification information of the fourth screening condition.

The state information of the SMF stored by the NRF may include only the first state information of the SMF, or may include both the first state information and the second state information of the SMF.

If the NRF only stores the first status information of the SMFs, the NRF may query the stored information of the SMFs corresponding to the fourth filtering condition, and if the stored information of the SMFs corresponding to the fourth filtering condition is all the information of the available SMFs meeting the fourth filtering condition, where the SMFs meeting the fourth filtering condition and being available are all the information of the available SMFs meeting the fourth filtering condition, and these SMFs all have available UPFs under the fourth filtering condition. Therefore, if the NRF only stores the first state information of the SMF, the NRF only needs to query whether the information of the corresponding SMF exists under the fourth screening condition, which is a simple manner.

Or, if the NRF stores the first state information and the second state information of the SMF, the NRF may include both the information of the available SMF and the information of the unavailable SMF in the information of the SMF corresponding to the fourth filtering condition stored in the NRF, and the NRF may have two processing manners:

in the first processing mode, the NRF screens the information of the available SMF from the stored information of the SMF corresponding to the fourth screening condition, where the SMF corresponding to the information of the SMF is the available SMF meeting the fourth screening condition, and it is needless to say that there is information of the available SMF in the stored information of the SMF corresponding to the fourth screening condition;

in a second processing manner, the NRF determines information of all stored SMFs corresponding to the fourth filtering condition, where the SMFs corresponding to the information of the SMFs may include available SMFs satisfying the fourth filtering condition, or may include unavailable SMFs satisfying the fourth filtering condition, or may include available SMFs satisfying the fourth filtering condition and unavailable SMFs satisfying the fourth filtering condition.

S708, the NRF sends the screening result to the AMF, and then the AMF receives the screening result.

For example, the NRF may call the nrrf _ NFDiscovery _ Request response service method of the NRF to send the filtering result to the AMF.

Wherein the screening result indicates whether there is an available SMF that satisfies a fourth screening condition.

For example, the NRF may transmit the screening result to the AMF based on the nrrf _ NFDiscovery _ Request service method of the NRF.

If the NRF only stores the first state information of the SMF, the NRF only needs to query whether there is information of a corresponding SMF under the fourth filtering condition, for example, there are information of K corresponding SMFs under the fourth filtering condition, and the NRF may send the information of K SMFs as a filtering result to the AMF, where the K SMFs are available SMFs satisfying the fourth filtering condition, and K is a positive integer. Alternatively, if the information of the corresponding SMF does not exist under the fourth filtering condition, which indicates that there is no available SMF satisfying the fourth filtering condition, the NRF may send a failure indication to the AMF, where the filtering result is the failure indication, and the failure indication may indicate that there is no available SMF satisfying the fourth filtering condition. For example, the NRF may send the filtering result to the AMF by sending a message, and one implementation of the failure indication is a message with empty content, and if the message sent by the NRF to the AMF is empty, it indicates that there is no SMF available that satisfies the fourth filtering condition; or, another implementation manner of the failure indication is a specific indication code, for example, a failure code (failure code), and if a message sent by the NRF to the AMF carries the indication code, it indicates that there is no available SMF meeting the fourth filtering condition, and the embodiment of the present application does not limit an implementation manner of the failure indication. Of course, if there are K available SMFs satisfying the fourth filtering condition, the NRF may carry information of the K SMFs in the message and send the message to the SMF.

In one implementation, if the NRF stores the first state information and the second state information of the SMFs and the NRF adopts the first processing manner described in S605, if the NRF queries that it is determined that there is available SMF information in the stored SMF information corresponding to the fourth filtering condition, the NRF may send information of K SMFs, which are available SMFs satisfying the fourth filtering condition, to the AMF as the filtering result. Alternatively, if there is no information about the corresponding SMF under the fourth filtering condition, which indicates that there is no SMF available that satisfies the fourth filtering condition, the NRF may also send a failure indication to the AMF, and the description of the failure indication may refer to the contents of the previous paragraph.

In another implementation, if the NRF stores the first status information and the second status information of the SMFs, and the NRF adopts the second processing manner described in S707, the NRF queries the stored information of all SMFs corresponding to the fourth filtering condition, and as long as the fourth filtering condition corresponds to the information of the SMFs, the NRF may send the information of the SMFs to the AMF, and of course, the NRF may send the status information of the SMFs to the AMF, where the SMFs may all be SMFs available under the fourth filtering condition, or may all be SMFs unavailable under the fourth filtering condition, or may include both SMFs available under the fourth filtering condition and SMFs unavailable under the fourth filtering condition, and in short, the NRF may be sent directly to the AMF without filtering, and may be filtered by the AMF. That is, the AMF may determine from the received state information of the SMFs whether there is an available SMF satisfying the fourth filtering condition. If the NRF query determines that the fourth filtering condition does not have the information of the corresponding SMF, the NRF may also send a failure indication to the AMF, and the description of the failure indication may continue with reference to the foregoing.

For example, the AMF may determine the statuses of the SMFs from the NRFs according to the received status information of the SMFs, and if it is determined that the SMFs are all SMFs available under the fourth filtering condition, the AMF may select all or part of the SMFs; alternatively, if some of the SMFs are determined to be SMFs available under the fourth screening condition and the remaining SMFs are SMFs not available under the fourth screening condition, the AMF may select all or part of the SMFs available under the fourth screening condition; alternatively, if it is determined that these SMFs are all SMFs that are not available under the fourth screening condition, the AMF determines that there are no available SMFs that satisfy the fourth screening condition.

The information of the K SMFs sent by the NRF to the AMF may be FQDN or IP addresses of the K SMFs, or may be other information of the SMFs.

According to the technical scheme provided by the embodiment of the application, the SMF information obtained by the AMF can be used as the available SMF information under the screening condition requested by the AMF, so that the AMF selects the SMF, the available UPF can be selected when the SMF selects the UPF, the situation that the SMF cannot select the available UPF is avoided as much as possible, the probability of reselecting the SMF by the AMF is reduced, the time delay of the PDU session creating process is reduced, the SMF selecting efficiency is improved, and the probability of activation failure is also reduced.

In order to solve the same technical problem, please refer to fig. 8 again, an embodiment of the present application further provides a method for selecting a session management function network element, which is performed by the session management function network element 101 and the network function repository function network element 102 included in the system 100 for selecting a session management function network element provided in the embodiment shown in fig. 1, that is, SMF and NRF, as an example when the method is applied to the scenario shown in fig. 2, fig. 3 or fig. 4, and of course, in the implementation process of the method, a mobility management function network element and a user plane function network element, that is, AMF and UPF, as described below are also involved. In addition, the embodiment of the present application may roughly include two processes, a first process is referred to as a state synchronization process, for example, and may occur before the PDU session is created or in a process of creating the PDU session, and a second process is referred to as a process of selecting an SMF, for example, and may occur in a process of creating the PDU session.

S801, configuring and selecting a policy table for the SMF and the AMF.

Regarding the description of S801, reference may be made to the description of S701 in the embodiment shown in fig. 7, and the content is the same, which is not repeated.

S802, the SMF sends a subscription request to the NRF, then the NRF receives the subscription request, the subscription request carries subscription parameters, and the subscription parameters are the information of UPFs which the SMF is interested in, namely the information of UPFs which the SMF needs to subscribe to. Subscription parameters include, for example, DNN, S-NSSAI, SMF region identification, and the like.

For example, the SMF may call the NRF _ NFManagement _ nfstatussubscriber service method of the NRF to initiate a subscription to the NRF, that is, call the NRF _ NFManagement _ nfstatussubscriber service method of the NRF to send a subscription request to the NRF.

S803, if the NRF sends a notification message to the SMF, the SMF receives the notification message, where the notification message carries information of the UPF currently conforming to the subscription parameter. In fig. 8, the notification message in S803 is referred to as a first notification message.

For example, the NRF may call the nrrf _ NFManagement _ nfstatustnotify service method to send a first notification message to the SMF.

If there is no UPF meeting the subscription parameters currently, the NRF may not need to execute S803, or the NRF may execute S803, but in S803, the first notification message sent by the NRF to the SMF carries notification information instead of information of the UPF meeting the subscription parameters, where the notification information is used to notify the SMF that there is no UPF meeting the subscription parameters currently.

The process of sending the information of the UPF to the NRF by the UPF includes the following steps S804 to S806, where the following steps S804 to S806 may also be understood as a process that occurs after a new UPF is deployed in the system:

and S804, deploying a new UPF to the system, and completing configuration.

The OAM system may configure the identification information of the NRF on the UPF and configure the attribute information for the UPF. I.e., information configuring the UPF.

S805, the UPF sends a request message, for example, called a third request message, to the NRF, and the NRF receives the third request message, where the third request message carries an NF type of the UPF, an FQDN, or an IP address of an N4 interface, and attribute information configured by the OAM for the UPF.

For example, the UPF may call the nrrf _ NFManagement _ NFRegister service method of the NRF to register with the NRF, that is, call the nrrf _ NFManagement _ NFRegister service method of the NRF to transmit the third request message to the NRF.

S806, because of the subscription operation in S802, if the information of the UPF conforms to the subscription parameter of the SMF, that is, the UPF conforms to the subscription request of the SMF, the NRF may send a notification message to the SMF, and the SMF receives the notification message, where the notification message carries the information of the UPF. For example, the information of the UPF carried by the notification message may be the FQDN or IP address of the N4 interface of the UPF. In fig. 8, the notification message in S806 is referred to as a second notification message.

Of course, if the information of the UPF does not conform to the subscription parameters of the SMF, i.e. the UPF does not conform to the subscription request of the SMF, the NRF does not need to perform S806.

S807, the SMF classifies and stores the information of the UPF into a UPF state parameter table.

Regarding the description of S807, reference may be made to the description of S704 in the embodiment shown in fig. 7, and the contents are the same and are not repeated.

And S808, SMF decision, namely whether the SMF is available under the screening condition.

Regarding the description of S808, reference may be made to the description of S705 in the embodiment shown in fig. 7, and the content is the same and will not be described again.

S809, if the SMF sends the first status information of the SMF to the NRF, the NRF receives the first status information of the SMF from the SMF, where the first status information of the SMF is used to indicate that the SMF is available under the screening condition, and the first status information is used to select the SMF.

For example, the SMF may call the nrrf _ NFManagement _ NFUpdate service method of the NRF to send the first state information of the SMF to the NRF.

Regarding the description of S809, reference may be made to the description of S706 in the embodiment shown in fig. 7, and details are not repeated.

As described in S801 to S809, these steps belong to the status synchronization process included in the embodiment of the present application, and occur before or in the process of creating the PDU session, and S810 to S811 are described below, these steps belong to the process of selecting an SMF included in the embodiment of the present application, and occur in the process of creating the PDU session.

S810, the AMF sends a request message to the NRF, and the NRF receives the request message from the AMF, where the request message is used to request to obtain information of the SMF meeting the fourth filtering condition. In fig. 8, the request message of S810 is referred to as a fourth request message, for example.

For example, the AMF may call the nrrf _ NFDiscovery _ Request service method of the NRF to query the SMF satisfying the fourth filtering condition, that is, the AMF may call the nrrf _ NFDiscovery _ Request service method of the NRF to send the fourth Request message to the NRF.

Regarding the description of S810, reference may be made to the description of S707 in the embodiment shown in fig. 7, and the contents are the same and are not repeated.

S811, the NRF sends the screening result to the AMF, and then the AMF receives the screening result.

Regarding the description of S811, reference may be made to the description of S708 in the embodiment shown in fig. 7, and the content is the same and will not be described again.

In the embodiment of the application, the SMF can obtain the UPF information by subscribing to the NRF, and the SMF can directly obtain the UPF information subsequently only by performing a subscription operation once without sending too much information by the SMF, thereby reducing the interaction process between the SMF and the UPF.

In both the embodiment shown in fig. 7 and the embodiment shown in fig. 8, the SMF sets the state of the SMF, and sends the state information of the SMF to the NRF, and when the AMF requests the NRF, the NRF directly determines whether there is an available SMF that satisfies the filtering condition requested by the AMF according to the stored state information of the SMF. Instead of this, the state of the SMF may be determined by the NRF, i.e. the SMF need not set the state of the SMF, and the NRF may determine the state of the SMF itself after receiving the request of the AMF.

In view of this, referring to fig. 9, an embodiment of the present application further provides a method for selecting a session management function network element, and in the following description, continuing to take the application of the method in the scenario shown in fig. 2, fig. 3 or fig. 4 as an example, the method may be performed by the session management function network element 101 and the network function repository function network element 102 included in the system 100 for selecting a session management function network element provided in the embodiment shown in fig. 1, that is, SMF and NRF described below, and of course, in the implementation of the method, a mobility management function network element and a user plane function network element, that is, AMF and UPF described below are also involved. In addition, the embodiment of the present application also includes two processes, where S901 to S904 belong to a first process, the first process is also referred to as an information acquisition process, for example, and may occur before the PDU session is created or in the process of creating the PDU session, and S905 and the subsequent steps belong to a second process, the first process is also referred to as a process of selecting an SMF, for example, and may occur in the process of creating the PDU session.

S901, selecting a strategy table for the SMF and AMF configuration.

Regarding the description of S901, reference may be made to the description of S701 in the embodiment shown in fig. 7, or to the description of S801 in the embodiment shown in fig. 8, which is the same and is not repeated.

And S902, deploying a new UPF to the system and completing configuration.

S903, the UPF sends a request message, for example, called a third request message, to the NRF, and the NRF receives the third request message, where the third request message carries an NF type of the UPF, an FQDN, or an IP address of an N4 interface, and attribute information configured by the OAM for the UPF.

Regarding the description of S903, reference may be made to the description of S805 in the embodiment shown in fig. 8, and the contents are the same and are not repeated.

S904, the AMF sends a request message to the NRF, and the NRF receives the request message from the AMF, where the request message is used to request to obtain information of the SMF that meets the fourth filtering condition. In fig. 9, this request message is referred to as a fourth request message, for example.

Regarding the description of S904, reference may be made to the description of S707 in the embodiment shown in fig. 7, or to the description of S810 in the embodiment shown in fig. 8, which is the same and is not repeated.

S905, NRF determines whether there is an available SMF satisfying the fourth screening condition.

The NRF may query according to the fourth filtering condition to determine whether there is an SMF satisfying the fourth filtering condition, and if there is an SMF satisfying the fourth filtering condition, the NRF further determines whether these SMFs satisfying the fourth filtering condition are SMFs available under the fourth filtering condition, that is, determines whether these SMFs have UPFs available under the fourth filtering condition, respectively, or determines whether there is a UPF satisfying the fourth filtering condition among the UPFs associated with these SMFs, respectively, and if there is a UPF satisfying the fourth filtering condition among the UPFs associated with the SMFs, such an SMF is an available SMF satisfying the fourth filtering condition.

S906, the NRF sends the screening result to the AMF, and then the AMF receives the screening result.

If the NRF determines that there are SMFs available that satisfy the fourth filtering condition, the NRF may send information of these SMFs to the AMF as a filtering result, for example, the NRF may send FQDN or IP addresses of these SMFs to the AMF as a filtering result, or of course, other information of the SMFs may be sent to the AMF as a filtering result. Alternatively, if the NRF determines that there is no available SMF with the fourth filtering condition, the NRF may send a failure indication to the AMF, where the failure indication may be used to indicate that there is no available SMF with the fourth filtering condition, and the failure indication may refer to the related description of S708 in the embodiment shown in fig. 7, which is not repeated herein.

In the embodiment of the application, the SMFs which meet the screening condition and are available can be selected by the NRF, the SMF is not required to be set in the state, and the burden of the SMF is reduced.

The above-mentioned scheme provided by the embodiment of the present application is introduced mainly from the perspective of interaction between network elements. It is to be understood that the above-described implementation of each network element includes, in order to implement the above-described functions, a corresponding hardware structure and/or software module for performing each function. Those of skill in the art will readily appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as hardware or combinations of hardware and computer software. Whether a function is performed as hardware or computer software drives hardware depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the embodiments of the present application.

Based on the same inventive concept, as shown in fig. 10, a schematic diagram of an apparatus provided in the present application, which may be a session management function network element 101, a mobility management function network element, a network function repository function network element 102, or a chip, may perform the method of any of the foregoing embodiments. When the apparatus is a session management function network element 101 or chip, the apparatus 1000 may be configured to perform the operations performed by the SMF in the embodiment shown in any one of fig. 7 to 9. When the apparatus is a mobility management function network element or chip, the apparatus 1000 may be configured to perform the operations performed by the AMF in the embodiment shown in any one of fig. 7 to 9. When the apparatus is a network function repository function network element 102 or chip, the apparatus 1000 may be used to perform the operations performed by the NRF in the embodiment shown in any one of fig. 7-9.

The device 1000 includes at least one processor 1001, communication lines 1002, memory 1003 and at least one communication interface 1004.

The processor 1001 may be a general-purpose Central Processing Unit (CPU), a microprocessor, an Application Specific Integrated Circuit (ASIC), or one or more ics for controlling the execution of programs in accordance with the present disclosure.

Communication link 1002 may include a path to communicate information between the aforementioned components.

The communication interface 1004 may be any device, such as a transceiver, for communicating with other devices or communication networks, such as an ethernet, a Radio Access Network (RAN), a Wireless Local Area Network (WLAN), a wired access network, etc.

The memory 1003 may be, but is not limited to, a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a Random Access Memory (RAM) or other type of dynamic storage device that can store information and instructions, an electrically erasable programmable read-only memory (EEPROM), a compact disk read-only memory (CD-ROM) or other optical disk storage, optical disk storage (including compact disk, laser disk, optical disk, digital versatile disk, blu-ray disk, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. The memory may be separate and coupled to the processor via a communication link 1002. The memory may also be integral to the processor.

The memory 1003 is used for storing computer-executable instructions for executing the present invention, and is controlled by the processor 1001. The processor 1001 is configured to execute the computer-executable instructions stored in the memory 1003, so as to implement the method for selecting the network element with the session management function provided in the foregoing embodiment of the present application.

Optionally, the computer-executable instructions in the embodiments of the present application may also be referred to as application program codes, which are not specifically limited in the embodiments of the present application.

In particular implementations, processor 1001 may include one or more CPUs such as CPU0 and CPU1 of fig. 10, for example, as one embodiment.

In particular implementations, apparatus 1000 may include multiple processors, such as processor 1001 and processor 1008 in fig. 10, for example, as an example. Each of these processors may be a single-core (single-CPU) processor or a multi-core (multi-CPU) processor. A processor herein may refer to one or more devices, circuits, and/or processing cores for processing data (e.g., computer program instructions).

When the apparatus shown in fig. 10 is a chip, for example, it may be a chip of the session management function network element 101, or a chip of the mobility management function network element, or a chip of the network function repository function network element 102, and then the chip includes a processor 1001 (which may also include the processor 1008), a communication line 1002, a memory 1003, and a communication interface 1004. In particular, the communication interface 1004 may be an input interface, a pin or a circuit, or the like. The memory 1003 may be a register, cache, or the like. The processor 1001 and the processor 1008 may be a general-purpose CPU, a microprocessor, an ASIC, or one or more integrated circuits for controlling the execution of programs of the method for selecting a session management function network element of any of the above embodiments.

In the embodiment of the present application, functional modules of the apparatus may be divided according to the above method example, for example, each functional module may be divided corresponding to each function, or two or more functions may be integrated into one processing module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. 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. For example, in the case of dividing each functional module by corresponding functions, fig. 11 shows a schematic diagram of an apparatus, where the apparatus 1100 may be the session management functional network element 101, or the mobility management functional network element, or the network function repository functional network element 102, or a chip in the session management functional network element 101, or a chip in the mobility management functional network element, or a chip in the network function repository functional network element 102, which are involved in the foregoing embodiments. The apparatus 1100 comprises a transceiving unit 1101 and a processing unit 1102.

In an embodiment, when the apparatus 1100 is the session management function network element 101 or the chip of the session management function network element 101 of the above-mentioned embodiment, then,

a processing unit 1102, configured to determine whether there is a user plane functional network element that meets the screening condition;

a transceiver unit 1101, configured to send, if the processing unit 1102 determines that there is a user plane function network element that meets the screening condition, first state information of the session management function network element 101 to a network function repository function network element 102, where the first state information of the session management function network element 101 is used to indicate that the session management function network element 101 is available under the screening condition, and the first state information is used to select a session management function network element.

In one possible implementation, the first status information includes:

information indicating that the session management function network element is available under the screening condition; or the like, or, alternatively,

and indicating that the session management function network element has the information of the user plane function network element meeting the screening condition.

In a possible implementation manner, the processing unit 1102 is specifically configured to:

acquiring information of at least one user plane functional network element, and determining whether the at least one user plane functional network element has a user plane functional network element meeting the screening condition according to the information of the at least one user plane functional network element; or the like, or, alternatively,

and determining that no user plane function network element meeting the screening condition exists when the information of the user plane function network element is not acquired.

In a possible implementation manner, the processing unit 1102 is configured to obtain information of at least one user plane function network element specifically includes:

for receiving information of the at least one user plane function network element from the at least one user plane function network element, wherein the information of the one user plane function network element is from the one user plane function network element; or the like, or, alternatively,

the ue is configured to send a subscription message to the network function repository function network element 102, where the subscription message is used to subscribe to the information of the user plane function network element that meets the screening condition, receive a notification message from the network function repository function network element 102, and obtain the information of the at least one user plane function network element according to the notification message.

For example, the processing unit 1102 may receive, through the transceiver unit 1101, information of the at least one user plane function network element from the at least one user plane function network element, send a subscription message to the network function repository function network element 102 through the transceiver unit 1101, and may also receive, through the transceiver unit 1101, a notification message from the network function repository function network element.

In one possible implementation, the transceiving unit 1101 is further configured to:

if the processing unit 1102 determines that there is no user plane function network element that meets the screening condition, sending second state information of the session management function network element 101 to the network function repository function network element 102, where the second state information of the session management function network element 101 is used to indicate that the session management function network element 101 is unavailable under the screening condition; or the like, or, alternatively,

if the processing unit 1102 determines that there is no user plane function network element that meets the screening condition, it sends a deletion instruction to the network function repository function network element 102, where the deletion instruction is used to instruct the network function repository function network element 102 to delete the information of the session management function network element 101 from the information of the session management function network elements that are available under the screening condition.

In one possible implementation form of the method,

the screening condition is specifically a first screening condition, and the processing unit 1102 is configured to determine whether there is a user plane functional network element that meets the screening condition specifically includes:

determining whether a user plane function network element meeting the first screening condition exists;

or the like, or, alternatively,

the screening conditions are specifically a second screening condition and a third screening condition, and the processing unit 1102 is configured to determine whether there is a user plane functional network element that meets the screening conditions specifically includes:

and determining whether the user plane functional network element meeting the second screening condition exists or not, and determining whether the user plane functional network element meeting the third screening condition exists or not.

In a possible implementation manner, the transceiver unit 1101 is configured to send, to the network function repository function network element 102, first status information of the session management function network element 101 if there is a user plane function network element that meets the screening condition, where the first status information of the session management function network element 101 is used to indicate that the session management function network element 101 is available under the screening condition, and the method includes:

the screening condition is specifically the first screening condition, if the processing unit 1101 determines that there is a user plane function network element meeting the first screening condition, the transceiver unit 1101 sends first state information of the session management function network element 101 to the network function repository function network element 102, where the first state information of the session management function network element 101 is used to indicate that the session management function network element 101 is available under the first screening condition;

or the like, or, alternatively,

the screening conditions are specifically the second screening condition and the third screening condition, if the processing unit 1101 determines that there is a user plane function network element meeting the second screening condition, the transceiver unit 1101 sends first state information of the session management function network element 101 to the network function repository function network element 102, where the first state information of the session management function network element 101 is used to indicate that the session management function network element is available under the second screening condition; or, if the processing unit 1101 determines that there is a user plane function network element that meets the third screening condition, the transceiver unit 1101 sends the first status information of the session management function network element 101 to the network function repository function network element 102, where the first status information of the session management function network element 101 is used to indicate that the session management function network element 101 is available under the third screening condition.

In one possible implementation form of the method,

under the condition that the screening condition is specifically a first screening condition, if the first screening condition is null, the first screening condition is used for screening all user plane functional network elements; or the like, or, alternatively,

and if at least one of the second screening condition and the third screening condition is null, the at least one screening condition is used for screening all the user plane functional network elements.

In one possible implementation form of the method,

the first state information of the session management function network element 101 includes parameter information corresponding to the screening condition, and includes indication information for indicating that the session management function network element 101 is available under the screening condition; or the like, or, alternatively,

the first status information of the session management function network element 101 includes identification information of the screening condition, and includes indication information for indicating that the session management function network element 101 is available under the screening condition.

In yet another embodiment, when the apparatus 1100 is the network function repository function network element 102 or the chip of the network function repository function network element 102 of the above-mentioned embodiment, then,

a transceiver unit 1101, configured to receive a request message from a mobility management function network element, where the request message is used to request to obtain information of the session management function network element 101 that meets the fourth screening condition;

a processing unit 1102, configured to determine, according to state information of at least one session management function network element 101, whether there is an available session management function network element 101 that meets the fourth screening condition, where the state information of the at least one session management function network element 101 is used to indicate whether the at least one session management function network element 101 is in an available state under the fourth screening condition;

the transceiver 1101 is further configured to send a screening result to the mobility management function network element.

In a possible implementation manner, the state information of one session management function network element 101 includes:

information indicating that the one session management function network element 101 is an available session management function network element 101 that satisfies the fourth screening condition, or information indicating that the one session management function network element 101 is an unavailable session management function network element 101 that satisfies the fourth screening condition; or the like, or, alternatively,

indicating that the one session management function network element 101 has the user plane function network element that satisfies the fourth filtering condition, or indicating that the one session management function network element 101 does not have the user plane function network element that satisfies the fourth filtering condition.

In one possible implementation form of the method,

the screening result is specifically information of K session management function network elements 101, where the information of K session management function network elements 101 is used to indicate that the K session management function network elements 101 are available session management function network elements 101 that satisfy the fourth screening condition; or the like, or, alternatively,

the screening information is specifically a failure indication, where the failure indication indicates that there is no available session management function network element 101 that satisfies the fourth screening condition.

In one possible implementation, the state information of the at least one session management function network element 101 is from the at least one session management function network element 101.

In one possible implementation form of the method,

the status information of one session management function network element 101 in the at least one session management function network element 101 includes parameter information corresponding to at least one screening condition, and includes indication information for indicating whether the one session management function network element 101 is available under each of the at least one screening condition, where the at least one screening condition includes the fourth screening condition; or the like, or, alternatively,

the status information of one session management function network element 101 of the at least one session management function network element 101 includes identification information of at least one screening condition, and includes indication information for indicating whether the one session management function network element 101 is available under each of the at least one screening condition, where the at least one screening condition includes the fourth screening condition.

It should be understood that the apparatus may be configured to implement the steps executed by the session management function network element 101, the mobility management function network element, and the network function repository function network element 102 in the method according to the embodiment of the present application, and reference may be made to the above for related features, which are not described herein again.

Specifically, the functions/implementation processes of the transceiving unit 1101 and the processing unit 1102 in fig. 11 can be implemented by the processor 1001 in fig. 10 calling a computer execution instruction stored in the memory 1003. Alternatively, the function/implementation procedure of the processing unit 1102 in fig. 11 may be implemented by the processor 1001 in fig. 10 calling a computer executing instruction stored in the memory 1003, and the function/implementation procedure of the transceiving unit 1101 in fig. 11 may be implemented by the communication interface 1004 in fig. 10.

Alternatively, when the apparatus 1000 is a chip or a circuit, the functions/implementation processes of the transceiving unit 1101 can also be implemented by pins or circuits. Alternatively, when the apparatus 1000 is a chip, the memory 1003 may be a storage unit in the chip, such as a register, a cache, or the like. Of course, when the apparatus 1000 is the session management function network element 101, such as the session management function network element 101 in the foregoing embodiment, the memory 1003 may also be a storage unit located outside a chip in the session management function network element 101, which is not specifically limited in this embodiment of the present application. When the apparatus 1000 is a network function repository function network element 102, the memory 1003 may also be a memory unit located outside the chip in the network function repository function network element 102, which is not specifically limited in this embodiment of the present application.

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 application 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.

The various illustrative logical units and circuits described in this embodiment of the application may be implemented or operated by general purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination thereof. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other similar configuration.

The steps of a method or algorithm described in the embodiments herein may be embodied directly in hardware, in a software element executed by a processor, or in a combination of the two. The software cells may be stored in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. For example, a storage medium may be coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC, which may be disposed in a terminal device. In the alternative, the processor and the storage medium may reside as discrete components in a terminal device.

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.

Although the embodiments of the present application have been described in conjunction with specific features and embodiments thereof, it will be apparent that various modifications and combinations can be made thereto without departing from the spirit and scope of the embodiments of the present application. Accordingly, the present embodiments and figures are merely illustrative of the present embodiments as defined by the appended claims and are intended to cover any and all modifications, variations, combinations, or equivalents within the scope of the present embodiments. It will be apparent to those skilled in the art that various changes and modifications may be made in the embodiments of the present application without departing from the scope of the embodiments of the present application. Thus, if such modifications and variations of the embodiments of the present application fall within the scope of the claims of the embodiments of the present application and their equivalents, the embodiments of the present application are intended to include such modifications and variations as well.

Claims

1. A method of selecting a session management function network element, comprising:

determining whether a user plane functional network element meeting the screening condition exists;

and if the user plane function network element which meets the screening condition exists, sending first state information of the session management function network element to a network function repository function network element, wherein the first state information of the session management function network element is used for indicating that the session management function network element is available under the screening condition, and the first state information is used for selecting the session management function network element.

2. The method of claim 1, wherein the first state information comprises:

3. The method of claim 1 or 2, wherein determining whether there is a user plane function network element meeting the filtering condition comprises:

4. The method of claim 3, wherein obtaining information of at least one user plane function network element comprises:

receiving information of the at least one user plane function network element from the at least one user plane function network element, wherein the information of the one user plane function network element is from the one user plane function network element; or the like, or, alternatively,

and sending a subscription message to the network function repository function network element, wherein the subscription message is used for subscribing the information of the user plane function network element meeting the screening condition, receiving a notification message from the network function repository function network element, and obtaining the information of the at least one user plane function network element according to the notification message.

5. The method according to claim 1 or 2, wherein the screening condition comprises at least one of a data network name DNN and single network slice selection support information S-NSSAI.

6. The method according to claim 1 or 2, characterized in that the method further comprises:

if the user plane function network element which meets the screening condition does not exist, second state information of the session management function network element is sent to the network function repository function network element, and the second state information of the session management function network element is used for indicating that the session management function network element is unavailable under the screening condition; or the like, or, alternatively,

if the user plane function network element which meets the screening condition does not exist, sending a deletion instruction to the network function repository function network element, wherein the deletion instruction is used for indicating the network function repository function network element, and deleting the information of the session management function network element from the information of the session management function network element which is available under the screening condition.

7. The method according to claim 1 or 2,

the screening condition is specifically a first screening condition, and determining whether there is a user plane functional network element meeting the screening condition includes:

or the like, or, alternatively,

the screening conditions are specifically a second screening condition and a third screening condition, and determining whether there is a user plane functional network element meeting the screening conditions includes:

8. The method of claim 7, wherein if there is a user plane function network element that meets the screening condition, sending first status information of the session management function network element to a network function repository function network element, where the first status information of the session management function network element is used to indicate that the session management function network element is available under the screening condition, comprising:

the screening condition is specifically the first screening condition, and if there is a user plane function network element meeting the first screening condition, the first state information of the session management function network element is sent to a network function repository function network element, where the first state information of the session management function network element is used to indicate that the session management function network element is available under the first screening condition;

or the like, or, alternatively,

the screening conditions are specifically the second screening condition and the third screening condition, and if there is a user plane function network element meeting the second screening condition, the first state information of the session management function network element is sent to a network function repository function network element, where the first state information of the session management function network element is used to indicate that the session management function network element is available under the second screening condition; or, if there is a user plane function network element that meets the third screening condition, sending the first state information of the session management function network element to a network function repository function network element, where the first state information of the session management function network element is used to indicate that the session management function network element is available under the third screening condition.

9. The method according to claim 1 or 2,

10. The method according to claim 1 or 2,

the first state information of the session management function network element comprises parameter information corresponding to the screening condition and indication information used for indicating that the session management function network element is available under the screening condition; or the like, or, alternatively,

the first state information of the session management function network element includes identification information of the screening condition and indication information for indicating that the session management function network element is available under the screening condition.

11. A method of selecting a session management function network element, comprising:

receiving a request message from a mobility management function network element, wherein the request message is used for requesting to obtain information of a session management function network element meeting a fourth screening condition;

determining whether there is an available session management function network element meeting the fourth screening condition according to the state information of at least one session management function network element, where the state information of the at least one session management function network element is used to indicate whether the at least one session management function network element is in an available state under the fourth screening condition, and the at least one session management function network element is in an available state under the fourth screening condition means that the at least one session management function network element has an available user plane function network element under the fourth screening condition;

and sending a screening result to the mobility management function network element.

12. The method of claim 11, wherein the state information of a session management function network element comprises:

information indicating that the one session management function network element is an available session management function network element satisfying the fourth screening condition, or information indicating that the one session management function network element is an unavailable session management function network element satisfying the fourth screening condition; or the like, or, alternatively,

indicating that the one session management function network element has the information of the user plane function network element that satisfies the fourth screening condition, or indicating that the one session management function network element does not have the information of the user plane function network element that satisfies the fourth screening condition.

13. The method according to claim 11 or 12,

the screening result is specifically information of K session management function network elements, where the information of K session management function network elements is used to indicate that the K session management function network elements are available session management function network elements that meet the fourth screening condition; or the like, or, alternatively,

the screening information is specifically a failure indication, where the failure indication indicates that there is no available session management function network element that satisfies the fourth screening condition.

14. The method according to claim 11 or 12, characterized in that the method further comprises:

the state information of the at least one session management function network element is from the at least one session management function network element.

15. The method according to claim 11 or 12,

the status information of one session management function network element of the at least one session management function network element includes parameter information corresponding to at least one screening condition, and includes indication information for indicating whether the one session management function network element is available under each of the at least one screening condition, where the at least one screening condition includes the fourth screening condition; or the like, or, alternatively,

the status information of one of the at least one session management function network element includes identification information of at least one screening condition, and includes indication information for indicating whether the one session management function network element is available under each of the at least one screening condition, where the at least one screening condition includes the fourth screening condition.

16. A system for selecting a session management function network element, comprising:

the session management function network element is used for determining whether a user plane function network element meeting a screening condition exists, and if the user plane function network element meeting the screening condition exists, sending first state information of the session management function network element to a network function repository function network element, wherein the first state information of the session management function network element is used for indicating that the session management function network element is available under the screening condition, and the first state information is used for selecting the session management function network element;

the network function repository function network element is configured to receive the first status information.

17. The system of claim 16, wherein the first status information comprises:

18. The system according to claim 16 or 17, wherein the network function repository function network element is further configured to:

receiving a request message from a mobility management function network element, wherein the request message is used for requesting to obtain information of a session management function network element meeting a fourth screening condition; the session management functional network element meeting the fourth screening condition means that the session management functional network element has a user plane functional network element meeting the fourth screening condition;

determining whether an available session management function network element meeting the fourth screening condition exists according to state information of at least one session management function network element, wherein the state information of the at least one session management function network element is used for indicating whether the at least one session management function network element is in an available state under the fourth screening condition;

19. An apparatus for selecting a session management function network element, comprising:

the processing unit is used for determining whether the user plane functional network element which meets the screening condition exists;

a receiving and sending unit, configured to send first state information of the device to a network function repository function network element if the processing unit determines that there is a user plane function network element that meets the screening condition, where the first state information of the device is used to indicate that the device is available under the screening condition, and the first state information is used to select a session management function network element.

20. The apparatus of claim 19, wherein the first status information comprises:

information indicating that the apparatus is available under the screening condition; or the like, or, alternatively,

information indicating that the device has a user plane function network element that satisfies the screening condition.

21. The apparatus according to claim 19 or 20, wherein the processing unit is specifically configured to:

22. The apparatus of claim 21, wherein the processing unit configured to obtain information of at least one user plane function network element specifically comprises:

and the network function repository function network element is configured to send a subscription message to the network function repository function network element, where the subscription message is used to subscribe to information of the user plane function network element that meets the screening condition, and receive a notification message from the network function repository function network element, and obtain information of the at least one user plane function network element according to the notification message.

23. The apparatus according to claim 19 or 20, wherein the transceiver unit is further configured to:

if the processing unit determines that there is no user plane function network element meeting the screening condition, sending second status information of the device to the network function repository function network element, where the second status information of the device is used to indicate that the device is unavailable under the screening condition; or the like, or, alternatively,

if the processing unit determines that there is no user plane function network element meeting the screening condition, sending a deletion instruction to the network function repository function network element, where the deletion instruction is used to instruct the network function repository function network element, and deleting the information of the device from the information of the session management function network element available under the screening condition.

24. The apparatus of claim 19 or 20,

the screening condition is specifically a first screening condition, and the processing unit is configured to determine whether there is a user plane function network element that meets the screening condition specifically includes: determining whether a user plane function network element meeting the first screening condition exists;

or the like, or, alternatively,

the screening conditions are specifically a second screening condition and a third screening condition, and the processing unit is configured to determine whether there is a user plane functional network element that meets the screening conditions specifically includes: and determining whether the user plane functional network element meeting the second screening condition exists or not, and determining whether the user plane functional network element meeting the third screening condition exists or not.

25. The apparatus of claim 24, wherein the transceiver unit is configured to send first status information of the apparatus to a network function repository function network element if the processing unit determines that there is a user plane function network element that meets the screening condition, and the first status information of the apparatus is used to indicate that the apparatus is available under the screening condition, and the method includes:

the screening condition is specifically the first screening condition, and if the processing unit determines that there is a user plane function network element meeting the first screening condition, the transceiver unit sends first status information of the apparatus to a network function repository function network element, where the first status information of the apparatus is used to indicate that the apparatus is available under the first screening condition;

or the like, or, alternatively,

the screening conditions are specifically the second screening condition and the third screening condition, and if the processing unit determines that there is a user plane function network element that meets the second screening condition, the transceiver unit sends first status information of the apparatus to a network function repository function network element, where the first status information of the apparatus is used to indicate that the apparatus is available under the second screening condition; or, if there is a user plane function network element that meets the third screening condition, the transceiver unit sends the first status information of the apparatus to a network function repository function network element, where the first status information of the apparatus is used to indicate that the apparatus is available under the third screening condition.

26. An apparatus for selecting a session management function network element, comprising:

a transceiver unit, configured to receive a request message from a mobility management function network element, where the request message is used to request to obtain information of a session management function network element that meets a fourth screening condition;

a processing unit, configured to determine, according to state information of at least one session management function network element, whether there is an available session management function network element that meets the fourth screening condition, where the state information of the at least one session management function network element is used to indicate whether the at least one session management function network element is in an available state under the fourth screening condition, and the at least one session management function network element is in an available state under the fourth screening condition, where the indication is that the at least one session management function network element has an available user plane function network element under the fourth screening condition;

the transceiver unit is further configured to send a screening result to the mobility management function network element.

27. The apparatus of claim 26, wherein the state information of a session management function network element comprises:

28. The apparatus of claim 26 or 27,