CN115514797A

CN115514797A - Backup SMF discovery method, device, electronic equipment and medium

Info

Publication number: CN115514797A
Application number: CN202110696517.9A
Authority: CN
Inventors: 叶海洋
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2021-06-23
Filing date: 2021-06-23
Publication date: 2022-12-23
Also published as: WO2022267688A1

Abstract

The utility model provides a standby SMF discovery method, which comprises the steps of receiving a discovery request message sent by an NF (network controller) and acquiring a selection parameter carried in the discovery request message, wherein the NF discovery request message is sent by the NF when detecting a first SMF fault corresponding to a current session, and the selection parameter comprises an identification of an SMF group and a service parameter; determining information of a second SMF corresponding to the selection parameter according to a mapping relation between the information of the SMF and the selection parameter, wherein the first SMF and the second SMF belong to the same SMF cluster of the same SMF group, the SMFs in the same SMF cluster are in a master-slave relation with each other, manage the same session and are configured with the same selection parameter; and sending an NF discovery response message carrying the information of the second SMF to the NF. When the SMF fails, the standby SMF of the failed SMF can be quickly determined based on the mapping relation, the standby SMF discovery process can be simplified, the system performance and the standby SMF discovery efficiency are improved, resources are saved, and network load overload is avoided. The present disclosure also provides an apparatus, a computer device, and a readable medium.

Description

Backup SMF discovery method, device, electronic equipment and medium

Technical Field

The present disclosure relates to the field of communications technologies, and in particular, to a method, an apparatus, an electronic device, and a medium for discovering a standby SMF.

Background

Application scenarios in vertical industries (e.g., coal mine, electric power, industrial control, etc.) require Ultra-high reliability and Ultra-low latency, and 3GPP (3 rd Generation Partnership Project) puts such scenarios into urrllc (Ultra-high reliable and low latency communication), and proposes an end-to-end Session redundancy scheme to improve reliability, which establishes two PDU sessions between UE (user equipment) and an enterprise application network.

In the urrllc dual PDU Session redundancy scheme, two redundant PDU sessions need to be established on two different SMFs (Session Management Function entities), respectively. When the two SMFs are in an SMF Set (SMF group), and when one of the SMFs fails, if an NF (Network Function) node arbitrarily selects one SMF from the SMF group as a standby SMF, it is possible to access two redundant PDU sessions to the same SMF, which does not meet the end-to-end redundancy requirement and reduces reliability. After selecting a standby SMF, in order to ensure that two redundant PDU sessions can fall on two different SMFs, a standby SMF discovery scheme currently exists, where when an SMF fails, all SMF information in an SMF group where the failed SMF is located is obtained first, and then the standby SMF of the failed SMF is selected from the SMF information, but the process of selecting the standby SMF in the scheme is complex. The urrllc is widely applied in the vertical industry, so there are a large number of users, and for an SMF carrying millions of sessions, if the above scheme is used to reselect a standby SMF after a failure occurs, the above-described complex processing procedure needs to be performed for each session, which consumes a great deal of resources, and may even cause overload on the core network.

Disclosure of Invention

The present disclosure provides a backup SMF discovery method, apparatus, electronic device, and medium.

In a first aspect, an embodiment of the present disclosure provides a standby SMF discovery method, including: the method comprises the steps that a NF discovery request message sent by a network function node NF is responded to and obtained, a selection parameter carried in the NF discovery request message is sent by the NF when a fault of a first session management function entity SMF corresponding to a current session is detected, the selection parameter comprises an identification of an SMF group and a service parameter, and the identification of the SMF group is the identification of a group where the first SMF is located;

determining information of a second SMF corresponding to a selection parameter according to a mapping relation between the information of the SMF and the selection parameter, wherein the first SMF and the second SMF belong to the same SMF cluster of the same SMF group, the SMFs in the same SMF cluster are in a master-slave relation with each other, manage the same session, and are configured with the same selection parameter;

and sending an NF discovery response message carrying the information of the second SMF to the NF.

In some embodiments, the method further comprises:

responding to a received NF registration request message sent by an SMF, and acquiring a selection parameter carried in the NF registration request message;

and establishing a mapping relation between the selection parameters and the SMF information.

In some embodiments, the traffic parameter is a redundant sequence number, RSN.

In some embodiments, a group of SMFs comprises at least two SMF clusters, the selection parameters of the SMFs belonging to different SMF clusters being different.

In another aspect, an embodiment of the present disclosure further provides a backup SMF discovery method, including:

responding to a detected fault of a first session management function entity (SMF) corresponding to a current session, and sending a network function Node (NF) discovery request message to a network data repository function entity (NRF), wherein the NF discovery request message carries selection parameters of the first SMF, the selection parameters comprise an identifier of an SMF group and service parameters, and the identifier of the SMF group is an identifier of a group where the first SMF is located;

receiving the NF discovery response message sent by the NRF, acquiring information of a second SMF carried in the NF discovery response message, and determining a standby SMF according to the information of the second SMF, wherein the information of the second SMF is determined by the NRF according to a mapping relation between the information of the SMF and a selection parameter and the selection parameter;

the first SMF and the second SMF belong to the same SMF cluster of the same SMF group, and the SMFs in the same SMF cluster are in a master-slave relationship with each other, manage the same session and are configured with the same selection parameters.

In some embodiments, the determining a standby SMF according to the information of the second SMF includes:

and in response to the information of the at least two second SMFs, randomly selecting one piece of information of the second SMF from the information of the second SMFs, and determining a standby SMF according to the selected information of the second SMF.

In some embodiments, before sending the NF discovery request message to the network data repository function, NRF, the method further comprises:

and receiving the selection parameters sent by the first SMF in a session establishment process.

In some embodiments, the receiving the selection parameter delivered by the first SMF includes:

receiving an N4session establishment message which is sent by the first SMF and carries the selection parameters under the condition that the network function node NF is a user plane function entity UPF;

and receiving a session management policy coupling establishment message which is sent by the first SMF and carries the selection parameters under the condition that the network function node NF is a policy control function entity PCF.

In some embodiments, the traffic parameter is a redundant sequence number, RSN.

sending a network function node NF registration request message to a network data repository function entity NRF, wherein the NF registration request message carries a selection parameter of the SMF so that the NRF establishes a mapping relation between information of the SMF and the selection parameter, and the selection parameter comprises an identifier and a service parameter of an SMF group where the SMF is located;

the SMF belongs to an SMF cluster in an SMF group, SMFs in the same SMF cluster are in a master-slave relationship with each other, manage the same session, and are configured with the same selection parameters.

In some embodiments, the method further comprises:

in the session establishment process, the selection parameters are issued to a network function node NF of the session in response to receiving a session establishment request message sent by user equipment.

In some embodiments, the issuing the selection parameter to the network function node NF of the session includes:

under the condition that the NF is a user plane functional entity UPF, sending an N4session establishment message carrying the selection parameters to the UPF;

and sending a session management policy coupling establishment message carrying the selection parameters to the PCF under the condition that the NF is a policy control function entity PCF.

In some embodiments, the traffic parameter is a redundant sequence number, RSN.

In another aspect, an embodiment of the present disclosure further provides a network data warehouse functional entity, including a receiving module, an obtaining module, a discovery module, and a sending module, where the receiving module is configured to receive an NF discovery request message sent by a network function node NF, and the NF discovery request message is sent by the NF when detecting that a first session management functional entity SMF corresponding to a current session fails;

the acquiring module is configured to acquire a selection parameter carried in the NF discovery request message, where the selection parameter includes an identifier of an SMF group and a service parameter, and the identifier of the SMF group is an identifier of a group in which the first SMF is located;

the discovery module is configured to determine, according to a mapping relationship between SMF information and a selection parameter, information of a second SMF corresponding to the selection parameter, where the first SMF and the second SMF belong to a same SMF cluster of a same SMF group, and SMFs in the same SMF cluster are in a master-slave relationship with each other, manage a same session, and are configured with the same selection parameter;

the sending module is configured to send, to the NF, an NF discovery response message carrying the information of the second SMF.

In another aspect, the present disclosure further provides a network function node, including a sending module, a receiving module, and a determining module, where the sending module is configured to send, in response to detecting that a first session management function entity SMF fault corresponding to a current session is detected, a network function node NF discovery request message to a network data repository function entity NRF, where the NF discovery request message carries a selection parameter of the first SMF, where the selection parameter includes an identifier of an SMF group and a service parameter, and the identifier of the SMF group is an identifier of a group in which the first SMF is located;

the receiving module is configured to receive an NF discovery response message sent by the NRF;

the determining module is configured to obtain information of a second SMF carried therein, and determine a standby SMF according to the information of the second SMF, where the information of the second SMF is determined by the NRF according to a mapping relationship between the information of the SMF and a selection parameter and the selection parameter; the first SMF and the second SMF belong to the same SMF cluster of the same SMF group, SMFs in the same SMF cluster are in a master-slave relationship with each other, manage the same session, and are configured with the same selection parameters.

In another aspect, an embodiment of the present disclosure further provides a session management function entity, including a registration module, where the registration module is configured to send a NF registration request message of a network function node to a network data repository function NRF, where the NF registration request message carries a selection parameter of a local SMF, so that the NRF establishes a mapping relationship between information of the local SMF and the selection parameter, and the selection parameter includes an identifier of an SMF group where the local SMF is located and a service parameter;

In another aspect, an embodiment of the present disclosure further provides an electronic device, including:

one or more processors;

a storage device having one or more programs stored thereon;

the one or more programs, when executed by the one or more processors, cause the one or more processors to implement the backup SMF discovery method as previously described.

In yet another aspect, the disclosed embodiments also provide a computer readable medium, on which a computer program is stored, where the program when executed implements the backup SMF discovery method as described above.

The embodiment of the disclosure provides a standby SMF discovery method, which includes receiving a discovery request message sent by an NF (network node), acquiring a selection parameter carried in the discovery request message, wherein the NF discovery request message is sent by the NF when detecting a first SMF fault corresponding to a current session, the selection parameter includes an identifier of an SMF group and a service parameter, and the identifier of the SMF group is an identifier of a group where the first SMF is located; determining information of a second SMF corresponding to the selection parameter according to a mapping relation between the information of the SMF and the selection parameter, wherein the first SMF and the second SMF belong to the same SMF cluster of the same SMF group, the SMFs in the same SMF cluster are in a master-slave relation with each other, manage the same session and are configured with the same selection parameter; and sending an NF discovery response message carrying the information of the second SMF to the NF. The method and the device have the advantages that the same selection parameters are configured for the SMFs which are mutually in the main-standby relationship, the selection parameters comprise the identification of the SMF group and the service parameters, and the mapping relationship between the SMF information and the selection parameters is pre-established, so that when the SMF fails, the standby SMF of the failed SMF can be quickly determined based on the mapping relationship, the information of all the SMFs in the SMF group where the failed SMF is located does not need to be acquired first, the standby SMF discovery process can be simplified, the system performance and the standby SMF discovery efficiency are improved, the resources are saved, and the network load overload is avoided.

Drawings

FIG. 1 is a schematic diagram of a system architecture provided by an embodiment of the present disclosure;

fig. 2 is a schematic flowchart of a standby SMF discovery method using NRF as an execution subject according to an embodiment of the present disclosure;

fig. 3 is a schematic flowchart of SMF to NRF registration according to an embodiment of the present disclosure;

fig. 4 is a flowchart illustrating a standby SMF discovery method using NF as an execution subject according to an embodiment of the present disclosure;

fig. 5 is a flowchart illustrating a standby SMF discovery method using an SMF as an execution subject according to an embodiment of the present disclosure;

fig. 6 is a signaling flowchart of a backup SMF discovery method in which UPF1 detects a SMF1 failure according to an embodiment of the present disclosure;

fig. 7 is a signaling flowchart of a standby SMF discovery method in which a PDF detects an SMF1 failure according to an embodiment of the present disclosure;

fig. 8 is a schematic signaling flow diagram of SMF to NRF registration according to an embodiment of the present disclosure;

FIG. 9 is a first schematic structural diagram of an NRF according to an embodiment of the present disclosure;

FIG. 10 is a second schematic structural view of an NRF provided in an embodiment of the present disclosure;

FIG. 11 is a schematic structural diagram of a NF provided by an embodiment of the disclosure;

fig. 12 is a first schematic structural diagram of an SMF according to an embodiment of the present disclosure;

fig. 13 is a second structural schematic diagram of an SMF provided in the embodiment of the present disclosure.

Detailed Description

Example embodiments will be described more fully hereinafter with reference to the accompanying drawings, but which may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, … … specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Embodiments described herein may be described with reference to plan and/or cross-sectional views in idealized representations of the present disclosure. Accordingly, the example illustrations can be modified in accordance with manufacturing techniques and/or tolerances. Accordingly, the embodiments are not limited to the embodiments shown in the drawings, but include modifications of configurations formed based on a manufacturing process. Thus, the regions illustrated in the figures have schematic properties, and the shapes of the regions shown in the figures illustrate specific shapes of regions of elements, but are not intended to be limiting.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

In a uRLLC double-PDU session scene, one SMF group comprises a plurality of SMFs, and the NFs in the SMF group are disaster-tolerant to each other. The conventional backup SMF discovery scheme is as follows: the two redundant PDU sessions respectively correspond to different S-NSSAI (Single Network Slice Selection Assistant Information, network Slice Selection support Information) + DNN (Digital Data Network) combination parameters, when a certain SMF fails, the NF acquires the Information of all SMFs in the SMF group, and then selects a proper standby SMF based on the S-NSSAI + DNN combination parameters of the current session. The above scheme requires at least two key steps: step one, acquiring all SMF information in an SMF group where a fault SMF is located; and secondly, selecting a standby SMF from all the SMFs obtained in the last step based on the S-NSSAI + DNN combined parameters, wherein the standby SMF is complex in discovery process and consumes a large amount of resources.

To this end, an embodiment of the present disclosure provides a backup SMF discovery method, which may be applied to a system shown in fig. 1, where as shown in fig. 1, the system at least includes: NRF (Network Repository Function), PCF (Policy Control Function), UE, access device (NG-RAN, 5G access Network), UPF (User Plane Function), DN (Data Network), and SMF, where UPF and PCF are collectively referred to as NF, and multiple SMFs form an SMF group, and the SMF group may be divided according to ToC (enterprise-oriented) or ToB (personal-oriented), and there may be multiple SMF groups. The standby SMF discovery method of the embodiment of the present disclosure may be applied to a dual-PDU session redundancy scenario of a urrllc, as shown in fig. 1, where two redundant PDU sessions are respectively established on different SMFs in the same SMF group, where PDU session 1 is established on SMF2 through UPF1, and PDU session 2 is established on SMF4 through UPF 2. UE is a terminal in the vertical industry, and for the same vertical industry service, two redundant PDU sessions can be triggered and established by using independent S-NSSAI + DNN combined parameters; the Master NG-RAN and the Secondary NG-RAN respectively serve user plane paths of two redundant PDU sessions established by the vertical industry service; UPF1 and UPF2 serve user plane paths of two redundant PDU sessions established by vertical industry services respectively, and are used for providing data forwarding and discovering a standby SMF of a failed SMF when the SMF fails; SMF1 and SMF2 may provide session management for PDU session 1, SMF3 and SMF4 may provide session management for another redundant PDU session (i.e., PDU session 2); the NRF provides SMF registration and SMF discovery functions; the PCF is a policy and charging control decision node for discovering its standby SMF (e.g. SMF 1) when it fails.

As shown in fig. 2, a standby SMF discovery method provided in an embodiment of the present disclosure includes the following steps:

step 11, in response to receiving an NF discovery request message sent by an NF, obtaining a selection parameter carried in the NF discovery request message, where the NF discovery request message is sent by the NF when detecting that a first SMF corresponding to a current session is faulty, the selection parameter includes an identifier of an SMF group and a service parameter, and the identifier of the SMF group is an identifier of a group in which the first SMF is located.

And when the NF detects that the first SMF corresponding to the current session fails, the NF sends an NF discovery request message carrying a selection parameter to the NRF, wherein the selection parameter is a combined parameter consisting of the identification service parameters of the SMF group, and the identification of the SMF group is the identification of the SMF group where the failed first SMF is located. In this step, the NRF obtains the selection parameters carried therein according to the received NF discovery request message. The NF may be a UPF or a PCF, and a PDU session needs to be implemented by direct or indirect interaction between the UPF and the PCF, respectively, and the SMF managing the PDU session, and thus, once the SMF fails, the PDU session can be detected by the UPF and the PCF managing the PDU session.

And step 12, determining the information of the second SMF corresponding to the selection parameter according to the mapping relationship between the information of the SMF and the selection parameter, wherein the first SMF and the second SMF belong to the same SMF cluster of the same SMF group, the SMFs in the same SMF cluster are in a master-slave relationship with each other, manage the same session, and are configured with the same selection parameter.

In the embodiment of the present disclosure, a mapping relationship between the information of the SMF and the selection parameter is established in the NRF in advance, and the information of the SMF may be, for example, an SMF identifier. One SMF group may be divided into at least one SMF cluster, where one SMF cluster includes at least two SMFs in a primary-backup relationship with each other, and each SMF in the same SMF cluster manages the same PDU session and is configured with the same selection parameters. For example, as shown in fig. 1, an SMF group includes two SMF clusters, an SMF cluster 1 includes an SMF1 and an SMF2, the SMF1 and the SMF2 are in a primary-standby relationship with each other, and the SMF1 and the SMF2 manage a PDU session 1; the SMF cluster 2 comprises SMF3 and SMF4, the SMF3 and the SMF4 are in a master-slave relationship with each other, and the SMF3 and the SMF4 manage a PDU session 2; since the two redundant PDU sessions shown in fig. 1 belong to the same SMF group, the identification of the SMF group in the selection parameters of PDU session 1 and PDU session 2 is the same, but the traffic parameters are different.

Because the SMFs belonging to the same SMF cluster and having the primary-backup relationship with each other have the same selection parameter and a mapping relationship between the information of the SMFs and the selection parameter is pre-established, each SMF in the same SMF cluster corresponds to the same selection parameter, and in this step, the NRF queries the mapping relationship according to the selection parameter to determine other standby SMFs belonging to the same SMF cluster as the first SMF.

And step 13, sending an NF discovery response message carrying the information of the second SMF to the NF.

In this step, the NRF carries the information of the second SMF obtained by the query in the NF discovery response message, and sends the NF to the NF, so that the NF determines the standby SMF according to the information of the second SMF.

The standby SMF discovery method provided by the embodiment of the disclosure receives a discovery request message sent by an NF (network node) and acquires a selection parameter carried in the discovery request message, wherein the NF discovery request message is sent by the NF when a first SMF fault corresponding to a current session is detected, the selection parameter comprises an identifier of an SMF group and a service parameter, and the identifier of the SMF group is an identifier of a group where the first SMF is located; determining information of a second SMF corresponding to the selection parameter according to a mapping relation between the information of the SMF and the selection parameter, wherein the first SMF and the second SMF belong to the same SMF cluster of the same SMF group, the SMFs in the same SMF cluster are in a master-slave relation with each other, manage the same session and are configured with the same selection parameter; and sending an NF discovery response message carrying the information of the second SMF to the NF. The method and the device have the advantages that the same selection parameters are configured for the SMFs which are mutually in the main-standby relationship, the selection parameters comprise the identification of the SMF group and the service parameters, and the mapping relationship between the SMF information and the selection parameters is pre-established, so that when the SMF fails, the standby SMF of the failed SMF can be quickly determined based on the mapping relationship, the information of all the SMFs in the SMF group where the failed SMF is located does not need to be acquired first, the standby SMF discovery process can be simplified, the system performance and the standby SMF discovery efficiency are improved, the resources are saved, and the network load overload is avoided.

In some embodiments, the standby SMF discovery method further includes a step of establishing a mapping relationship between the information of the SMF and the selection parameter, where the mapping relationship is established when the SMF is registered, and a process of establishing the mapping relationship between the information of the SMF and the selection parameter is described in detail below with reference to fig. 3.

As shown in fig. 3, establishing a mapping relationship between the SMF information and the selection parameter includes the following steps:

and step 21, in response to receiving the NF registration request message sent by the SMF, acquiring the selection parameters carried in the NF registration request message.

In this step, the SMF realizes SMF registration by sending an NF registration request message (NFRegister request) to the NRF, where the NF registration request message carries an NF profile (NFProfile), the NF profile includes selection parameters of the SMF, and the SMF includes the first SMF or the second SMF.

And step 22, establishing a mapping relation between the selection parameters and the SMF information.

In this step, the NRF establishes a mapping relationship between the information of the SMF and the selection parameter for the currently registered SMF, and stores the mapping relationship locally. It should be noted that each SMF needs to register with the NRF, so the NRF may establish and store a mapping relationship between information of each SMF and a corresponding selection parameter, and thus, when a subsequent NF initiates SMF discovery to the NRF, all matching SMFs (i.e., the second SMF) may be directly found by carrying the selection parameter.

In some embodiments, after establishing the mapping relationship between the selection parameter and the information of the SMF (i.e., step 22), the backup SMF discovery method may further include the steps of: and returning a NF registration Response message (NFRegister Response) to the SMF, wherein the NF registration Response message carries the NF configuration file.

In some embodiments, the traffic parameter is a traffic range used to indicate that the SMF can serve, for example, the traffic parameter may be RSN (redundant Sequence Number), that is, the selection parameter is a combination parameter of the identification of the SMF group + RSN.

The RSN field is the existing field in the Nnrf interface message of NRF and the N4 interface/N7 interface message of SMF, therefore, the RSN field of the interface message is expanded, the combined parameter of the identification of the SMF group and the RSN is taken as the selection parameter and carried in the RSN field, the transmission of the selection parameter is realized, the improvement on the existing protocol is small, and the scheme is easy to realize.

In some embodiments, a group of SMFs comprises at least two SMF clusters, the selection parameters of the SMFs belonging to different SMF clusters being different. This situation is a scenario of redundant PDU sessions, where different SMF clusters manage one PDU session in the redundant PDU session, and the selection parameters of SMFs in the same SMF cluster are the same, and the selection parameters corresponding to different SMF clusters are different, that is, the service parameters in the selection parameters are different (the identifiers of SMF groups are the same).

In a scenario of a redundant PDU session, according to the method for discovering a standby SMF provided by the embodiment of the present disclosure, not only can a standby SMF of a failed SMF be quickly and easily found, but also it can be ensured that the redundant PDU session is still managed by different SMFs, that is, the standby SMF is not the same SMF as the SMF managing another redundant PDU session, thereby satisfying the end-to-end redundancy requirement and ensuring reliability. Taking fig. 1 as an example, if the SMF1 fails, according to the scheme of the embodiment of the present disclosure, only the standby SMF is searched in the SMF cluster 1 where the SMF1 is located, so as to find the SMF2 as the standby SMF, and the SMF2 manages the PDU session 1, so that a situation that the standby SMF is an SMF in the SMF cluster 2 does not occur, that is, the PDU session 1 is not migrated to the SMF cluster of the PDU 2.

It should be noted that the embodiment of the present disclosure may also be applied to a scenario of a non-redundant session, that is, one SMF group includes only one SMF cluster, and a PDU session managed by each SMF of the SMF group does not have a redundancy relationship. In this scenario, according to the standby SMF discovery method provided by the embodiment of the present disclosure, the standby SMF of the failed SMF can also be quickly and easily found.

In the embodiment of the present disclosure, when the service parameter is RSN, for the vertical industry service, two redundant PDU sessions respectively correspond to two different RSN parameter values, and it should be noted that SMFs managing the two redundant PDU sessions belong to the same SMF group. In an SMF group, aiming at each SMF cluster, the SMF in the cluster is only configured with one RSN parameter value, thereby ensuring that only one of two redundant PDU sessions is managed, namely the SMFs which are in a primary-standby relationship are configured with the same RSN parameter value.

An embodiment of the present disclosure further provides a standby SMF discovery method, as shown in fig. 4, where the standby SMF discovery method includes the following steps:

step 31, in response to detecting that the first SMF fault corresponding to the current session is detected, sending an NF discovery request message to the NRF, where the NF discovery request message carries selection parameters of the first SMF, where the selection parameters include an identifier of an SMF group and service parameters, and the identifier of the SMF group is an identifier of a group in which the first SMF is located.

In this step, if the NF detects that the first SMF fails, the NF sends an NF discovery Request message (NFDiscovery Request) carrying the selection parameter of the first SMF to the NRF, so that the NRF searches for a mapping relationship between the information of the SMF and the selection parameter according to the selection parameter. It should be noted that the NF may be a UPF or a PCF.

And step 32, receiving the NF discovery response message sent by the NRF, acquiring the information of the second SMF carried in the NF discovery response message, and determining a standby SMF according to the information of the second SMF, where the information of the second SMF is determined by the NRF according to the mapping relationship between the information of the SMF and the selection parameter, where the first SMF and the second SMF belong to the same SMF cluster of the same SMF group, and the SMFs in the same SMF cluster are in the master-slave relationship with each other, manage the same session, and are configured with the same selection parameter.

After determining the information of the SMF corresponding to the selection parameter, the NRF returns an NF discovery Response message (NFDiscovery Response) to the NF. In this step, the NF acquires the information of the second SMF carried in the NF discovery response message, and determines a standby SMF according to the information of the second SMF.

In the embodiment of the present disclosure, a mapping relationship between the information of the SMF and the selection parameter is established in the NRF in advance, and the information of the SMF may be, for example, an SMF identifier. One SMF group comprises at least one SMF cluster, one SMF cluster comprises at least two SMFs which are in a primary-standby relationship with each other, and the SMFs in the same SMF cluster manage the same PDU session and are configured with the same selection parameters. For example, as shown in fig. 1, an SMF group includes two SMF clusters, an SMF cluster 1 includes an SMF1 and an SMF2, the SMF1 and the SMF2 are in a primary-standby relationship with each other, and the SMF1 and the SMF2 manage a PDU session 1; the SMF cluster 2 comprises SMF3 and SMF4, the SMF3 and the SMF4 are in a master-slave relationship with each other, and the SMF3 and the SMF4 manage a PDU session 2.

Because the SMFs belonging to the same SMF cluster and having the primary-standby relationship with each other have the same selection parameter, and the mapping relationship between the SMF information and the selection parameter is pre-established in the NRF, each SMF in the same SMF cluster corresponds to the same selection parameter, and in this step, the acquired information of the second SMF is the information of other SMFs in the SMF cluster where the first SMF is located.

In the standby SMF discovery method provided by the embodiment of the present disclosure, when a failure of a first SMF corresponding to a current session is detected, an NF discovery request message carrying a selection parameter of the first SMF is sent to an NRF, where the selection parameter includes an identifier of an SMF group and a service parameter, and the identifier of the SMF group is an identifier of a group in which the first SMF is located; receiving NF discovery response information sent by an NRF, acquiring information of a second SMF carried in the NF discovery response information, and determining a standby SMF according to the information of the second SMF, wherein the information of the second SMF is determined by the NRF according to a mapping relation between the information of the SMF and a selection parameter and the selection parameter, the first SMF and the second SMF belong to the same SMF cluster of the same SMF group, the SMFs in the same SMF cluster are in a master-slave relation with each other, manage the same session and are configured with the same selection parameter; the method and the device have the advantages that the same selection parameters are configured for the SMFs which are mutually in the main-standby relationship, the selection parameters comprise the identification of the SMF group and the service parameters, and the mapping relationship between the SMF information and the selection parameters is pre-established, so that when the SMF fails, the standby SMF of the failed SMF can be quickly determined based on the mapping relationship, the information of all the SMFs in the SMF group where the failed SMF is located does not need to be acquired first, the standby SMF discovery process can be simplified, the system performance and the standby SMF discovery efficiency are improved, the resources are saved, and the network load overload is avoided.

An SMF cluster comprises at least two SMFs which form a primary-standby relationship. When one SMF cluster includes three or more SMFs, in step 32, information of a plurality of second SMFs, each of which is an SMF that is in a primary-standby relationship with the first SMF, is acquired, and therefore, one of the plurality of second SMFs is selected as a final standby SMF.

Accordingly, in some embodiments, the determining a standby SMF based on the information about the second SMF (i.e., step 32) includes: and in response to the information of at least two second SMFs, randomly selecting one piece of information of the second SMF from the information of the second SMFs, and determining a standby SMF according to the selected information of the second SMF.

In some embodiments, before sending the NF discovery request message to the NRF (i.e. step 31), the method further comprises the steps of: and receiving the selection parameters sent by the first SMF in the session establishment process.

The PDU session establishment procedure is as follows: UE sends PDU conversation to Establish Request message (PDU Session establishment Request) to the first SMF, the PDU conversation Request message carries the combination parameter of S-NSSAI + DNN, after the first SMF issues the selection parameter of the first SMF to UPF and PCF, the first SMF returns PDU conversation to Establish Response message (PDU Session establishment Response) to UE.

In some embodiments, the receiving the selection parameter delivered by the first SMF includes: under the condition that the NF is the UPF, receiving an N4Session Establishment message (N4 Session Establishment) which is sent by the first SMF and carries the selection parameter; and receiving a session management Policy coupling Establishment message (SM Policy Association Establishment) which is sent by the first SMF and carries the selection parameters under the condition that the NF is the PCF. The first SMF sends an N4session establishment message to the UPF through the N4 interface to transmit the selection parameters to the UPF, and the first SMF sends a session management policy coupling establishment message to the PCF through the N7 interface to transmit the selection parameters to the PCF.

In some embodiments, after determining the backup SMF according to the information of the second SMF, the backup SMF discovery method may further include the steps of: under the condition that the NF is the UPF, sending an N4 conversation Report Request message (N4 Session Report Request) to the standby SMF; if the present NF is PCF, a session management Policy Association Modification message (SM Policy Association Modification) is sent to the standby SMF. And switching the main SMF and the standby SMF by sending the message.

In some embodiments, the traffic parameter is a traffic range used to indicate that the SMF can serve, for example, the traffic parameter may be RSN, that is, the selection parameter is a combination parameter of the identification of the SMF group + RSN.

An embodiment of the present disclosure further provides a standby SMF discovery method, as shown in fig. 5, where the standby SMF discovery method includes the following steps:

step 41, sending an NF registration request message to the NRF, where the NF registration request message carries a selection parameter of the SMF, so that the NRF establishes a mapping relationship between information of the SMF and the selection parameter, and the selection parameter includes an identifier of an SMF group where the SMF is located and a service parameter; the SMF belongs to an SMF cluster in an SMF group, SMFs in the same SMF cluster are in a master-slave relationship with each other, manage the same session, and are configured with the same selection parameters.

In this step, the SMF realizes SMF registration by sending an NF registration request message to the NRF, where the NF registration request message carries an NF configuration file (NFProfile), and the configuration file includes the selection parameter of the SMF, that is, the identifier and the service parameter of the SMF group in which the SMF is located.

In the standby SMF discovery method provided by the embodiment of the present disclosure, when the SMF initiates registration to the NRF, the selection parameter of the SMF is sent to the NRF, so that the NRF locally establishes a mapping relationship between the information of the SMF and the selection parameter, and thus, when the subsequent other nodes initiate SMF discovery to the NRF, all matched SMFs can be directly found by carrying the selection parameter. The method and the device have the advantages that the same selection parameters are configured for the SMFs which are mutually in the main-standby relationship, the selection parameters comprise the identification of the SMF group and the service parameters, and the mapping relationship between the SMF information and the selection parameters is pre-established, so that when the SMF fails, the standby SMF of the failed SMF can be quickly determined based on the mapping relationship, the information of all the SMFs in the SMF group where the failed SMF is located does not need to be acquired first, the standby SMF discovery process can be simplified, the system performance and the standby SMF discovery efficiency are improved, the resources are saved, and the network load overload is avoided.

In some embodiments, after sending the NF registration request message to the NRF (i.e., step 41), the standby SMF discovery method may further include the steps of: and receiving a NF registration Response message (NFRegister Response) returned by the NRF, wherein the NF registration Response message carries the NF configuration file.

In some embodiments, the backup SMF discovery method further comprises the steps of: in the process of session establishment, the selection parameters are issued to the NF in response to receiving a session establishment request message sent by the user equipment.

The PDU session establishment procedure is as follows: UE sends PDU conversation establishment Request message (PDU conversation establishment Request) to first SMF, PDU conversation Request message carries S-NSSAI + DNN combination parameter, first SMF sends PDU conversation establishment Response message (PDU conversation establishment Request) to UE after first SMF sends selection parameter of first SMF to UPF and PCF through different message.

In some embodiments, the issuing the selection parameters to the NF (i.e., step 41) includes the following steps: under the condition that the NF is the UPF, sending an N4Session Establishment message (N4 Session Establishment) carrying the selection parameters to the UPF; and sending a session management Policy coupling Establishment message (SM Policy Association Establishment) carrying the selection parameters to the PCF under the condition that the NF is the PCF. The SMF sends an N4session establishment message to the UPF through an N4 interface to transmit the selection parameters to the UPF, and the SMF sends a session management policy coupling establishment message to the PCF through an N7 interface to transmit the selection parameters to the PCF.

For clarity of describing the scheme of the embodiment of the present disclosure, the following describes, in conjunction with a specific example, a process of detecting SMF1 failure by UPF1 and discovering a standby SMF in detail. Fig. 6 is a signaling flowchart of a standby SMF discovery method in which UPF1 detects SMF1 failure according to an embodiment of the present disclosure, and as shown in fig. 6, a PDU session establishment procedure includes the following steps:

s1, UE sends PDU Session establishment Request message (PDU Session establishment Request) to SMF1, wherein the PDU Session Request message carries the combination parameter of S-NSSAI + DNN.

S2, SMF1 sends N4Session Establishment message (N4 Session Establishment) to UPF1, wherein the N4Session Establishment message carries a selection parameter consisting of the identification of the SMF group and RSN; SMF1 sends a session management Policy Association Establishment message (SM Policy Association Establishment) to PCF, wherein the session management Policy Association Establishment message carries a selection parameter consisting of the identifier of the SMF group and RSN.

And S3, the SMF1 returns a PDU Session establishment Response message (PDU Session establishment Response) to the UE.

As shown in fig. 6, when the UPF1 detects that the SMF1 fails, the following steps are performed:

s4, the UPF1 sends a NF discovery Request message (NFdiscovery Request) to the NRF, wherein the NF discovery Request message carries a selection parameter consisting of the identification of the SMF group and the RSN.

And S5, the NRF determines the information of the SMF2 corresponding to the selection parameter according to the mapping relation between the information of the SMF and the selection parameter (the identification of the SMF group + RSN).

S6, the NRF sends a NF discovery Response message (NFdiscovery Response) to the UPF1, wherein the NF discovery Response message carries the information of the SMF 2.

And S7, the UPF1 sends an N4Session Report Request message (N4 Session Report Request) to the SMF2 to complete the switching of the active SMF and the standby SMF.

The process of PCF detecting SMF1 failure and discovering a backup SMF is described in detail below with reference to a specific example. Fig. 7 is a signaling flowchart of a standby SMF discovery method in which a PCF detects a SMF1 failure according to an embodiment of the present disclosure, where a PDU session establishment procedure is not described herein again. As shown in fig. 7, PCF detects SMF1 failure and performs the following steps:

s4', the PCF sends a NF discovery Request message (NFdiscovery Request) to the NRF, wherein the NF discovery Request message carries a selection parameter consisting of the identification of the SMF group and the RSN.

S5', the NRF determines the SMF2 information corresponding to the selection parameter according to the mapping relation between the SMF information and the selection parameter (the SMF group identifier + RSN).

S6', the NRF sends a NF discovery Response message (NFdiscovery Response) to the PCF, wherein the NF discovery Response message carries the information of the SMF 2.

S7', PCF sends session management strategy coupling Modification message (SM Policy Association Modification) to SMF2 to complete the switching between the main SMF and the standby SMF.

The process of SMF registering to NRF is described in detail below with reference to a specific example. Fig. 8 is a signaling flow diagram of SMF registration to NRF. As shown in fig. 8, the registration of an SMF with an NRF includes the steps of:

s10, the SMF sends NF registration request information (NFRegister Requset) to the NRF, and the NF registration request information carries a selection parameter consisting of the identification of the SMF group and the RSN.

S20, the NRF establishes a mapping relationship between the selection parameter (the identification of the SMF group + RSN) and the information of the SMF.

S30, the NRF returns an NF registration Response message (NFregister Response) to the SMF, wherein the NF registration Response message carries the NF configuration file.

The embodiment of the disclosure can be applied to vertical industry application scenes such as industrial application and control, remote manufacturing, remote operation, traffic safety and control and the like, the scene provides requirements of ultrahigh reliability and ultrahigh low delay, and therefore, the 3GPP specially defines the uRLLC characteristic. In the vertical industry scene, the communication reliability is improved through end-to-end session redundancy, at the moment, the UE respectively uses independent DNN + S-NSSAI to establish two redundant PDU sessions, the two PDU sessions are respectively accessed to two independent SMFs, and meanwhile, a plurality of SMFs serving vertical industry services are in the same SMF group.

When the disclosed embodiment is applied to vertical industry application scenarios (such as coal mine, power, industrial control, etc.), for different SMFs in an SM group, if they can serve a urrllc dual redundant PDU session, a service parameter is configured for them, referring to the current 3GPP specification, i.e. the combined parameter of the identification of the SMF group + RSN. In order to ensure that the dual redundancy PDU session falls on two different SMFs, the two redundancy PDU sessions respectively correspond to two different RSN parameter values, and the two RSN parameter values are respectively configured on the different SMFs.

When a certain SMF in the SMF group has a fault, other NF reselects the SMF for the uRLLC session established on the fault SMF, so that all SMFs supporting the RSN can be directly selected from the SMF group in which the fault SMF is located, and then one SMF can be selected to replace the fault SMF. For an SMF carrying million-magnitude vertical industry redundancy PDU sessions, if the scheme of the embodiment of the disclosure is adopted to select a standby SMF after the SMF fails, the standby SMF can be selected for each PDU session in one step, so that the processing is simplified, the system performance is improved, the core network resources are saved, and the overload of loads is avoided.

Based on the same technical concept, an embodiment of the present disclosure further provides a network data repository function entity (NRF), as shown in fig. 9, including a receiving module 101, an obtaining module 102, a discovery module 103, and a sending module 104, where the receiving module 101 is configured to receive an NF discovery request message sent by a network function node NF, and the NF discovery request message is sent by the NF when detecting that a first session management function entity SMF corresponding to a current session fails.

The obtaining module 102 is configured to obtain a selection parameter carried in the NF discovery request message, where the selection parameter includes an identifier of an SMF group and a service parameter, and the identifier of the SMF group is an identifier of a group in which the first SMF is located.

The discovery module 103 is configured to determine, according to a mapping relationship between SMF information and a selection parameter, information of a second SMF corresponding to the selection parameter, where the first SMF and the second SMF belong to a same SMF cluster of a same SMF group, and SMFs in the same SMF cluster are in a master-slave relationship with each other, manage a same session, and are configured with the same selection parameter.

The sending module 104 is configured to send an NF discovery response message carrying the information of the second SMF to the NF.

In some embodiments, as shown in fig. 10, the network data repository functional entity may further include an establishing module 105, and the receiving module 101 is further configured to receive an NF registration request message sent by the SMF.

The obtaining module 102 is further configured to obtain the selection parameter carried in the NF registration request message.

The establishing module 105 is configured to establish a mapping relationship between the selection parameter and the information of the SMF.

In some embodiments, the traffic parameter is a redundant sequence number, RSN.

In some embodiments, a group of SMFs includes at least two SMF clusters, and SMFs belonging to different SMF clusters differ in their selection parameters.

The present disclosure further provides a network function Node (NF), as shown in fig. 11, including a sending module 201, a receiving module 202, and an obtaining module 203, where the sending module 201 is configured to, in response to detecting that a first session management function entity SMF corresponding to a current session is faulty, send a network function node NF discovery request message to a network data repository function entity NRF, where the NF discovery request message carries a selection parameter of the first SMF, where the selection parameter includes an identifier of an SMF group and a service parameter, and the identifier of the SMF group is an identifier of a group in which the first SMF is located.

The receiving module 202 is configured to receive a NF discovery response message sent by the NRF.

The determining module 203 is configured to acquire information of a second SMF carried therein, and determine a standby SMF according to the information of the second SMF, where the information of the second SMF is determined by the NRF according to a mapping relationship between the information of the SMF and a selection parameter and the selection parameter; the first SMF and the second SMF belong to the same SMF cluster of the same SMF group, SMFs in the same SMF cluster are in a master-slave relationship with each other, manage the same session, and are configured with the same selection parameters.

In some embodiments, the determining module 203 is configured to, in response to obtaining the information of at least two second SMFs, randomly select information of one second SMF from the information of the second SMFs, and determine a standby SMF according to the selected information of the second SMF.

In some embodiments, the receiving module 202 is further configured to receive the selection parameter sent by the first SMF in a session establishment procedure.

In some embodiments, the receiving module 202 is configured to receive, when the network function node NF is a user plane function entity UPF, an N4session establishment message that is sent by the first SMF and carries the selection parameter; and receiving a session management policy coupling establishment message which is sent by the first SMF and carries the selection parameters under the condition that the network function node NF is a policy control function entity PCF.

In some embodiments, the traffic parameter is a redundant sequence number, RSN.

The embodiment of the present disclosure further provides a session management function entity (SMF), as shown in fig. 12, including a registration module 301, where the registration module 301 is configured to send a network function node NF registration request message to a network data repository function entity NRF, where the NF registration request message carries a selection parameter of the SMF, so that the NRF establishes a mapping relationship between information of the SMF and the selection parameter, where the selection parameter includes an identifier of an SMF group where the SMF is located and a service parameter; the SMF belongs to an SMF cluster in an SMF group, SMFs in the same SMF cluster are in a master-slave relationship with each other, manage the same session, and are configured with the same selection parameters.

In some embodiments, as shown in fig. 13, the session management function entity further includes a parameter issuing module 302, where the parameter issuing module 302 is configured to, in a session establishment process, issue the selection parameter to a network function node NF of the session in response to receiving a session establishment request message sent by the user equipment.

In some embodiments, the parameter issuing module 302 is configured to, when the NF is a user plane functional entity UPF, send an N4session establishment message carrying the selection parameter to the UPF; and sending a session management policy coupling establishment message carrying the selection parameters to the PCF under the condition that the NF is a policy control function entity PCF.

In some embodiments, the traffic parameter is a redundant sequence number, RSN.

An embodiment of the present disclosure further provides an electronic device, including: one or more processors and storage; the storage device stores one or more programs thereon, and when the one or more programs are executed by the one or more processors, the one or more processors implement the standby SMF discovery method provided in the foregoing embodiments.

Embodiments of the present disclosure also provide a computer readable medium, on which a computer program is stored, where the computer program when executed implements the backup SMF discovery method provided in the foregoing embodiments.

It will be understood by those of ordinary skill in the art that all or some of the steps of the methods disclosed above, functional modules/units in the apparatus, may be implemented as software, firmware, hardware, and suitable combinations thereof. In a hardware implementation, the division between functional modules/units mentioned in the above description does not necessarily correspond to the division of physical components; for example, one physical component may have multiple functions, or one function or step may be performed by several physical components in cooperation. Some or all of the physical components may be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on computer readable media, which may include computer storage media (or non-transitory media) and communication media (or transitory media). The term computer storage media includes volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data, as is well known to those of ordinary skill in the art. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital Versatile Disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can accessed by a computer. In addition, communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media as is well known to those skilled in the art.

Example embodiments have been disclosed herein, and although specific terms are employed, they are used and should be interpreted in a generic and descriptive sense only and not for purposes of limitation. In some instances, features, characteristics and/or elements described in connection with a particular embodiment may be used alone or in combination with features, characteristics and/or elements described in connection with other embodiments, unless expressly stated otherwise, as would be apparent to one skilled in the art. It will therefore be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.

Claims

1. A method for standby SMF discovery, the method comprising:

responding to a received NF discovery request message sent by a network function node NF, acquiring a selection parameter carried in the NF, wherein the NF discovery request message is sent by the NF when detecting that a first session management function entity (SMF) corresponding to a current session is failed, the selection parameter comprises an identification of an SMF group and a service parameter, and the identification of the SMF group is the identification of a group where the first SMF is located;

2. The method of claim 1, wherein the method further comprises:

responding to a received NF registration request message sent by the SMF, and acquiring a selection parameter carried in the NF registration request message;

3. The method of claim 1, wherein the traffic parameter is a Redundant Sequence Number (RSN).

4. A method according to any of claims 1-3, characterized in that a group of SMFs comprises at least two SMF clusters, the selection parameters of the SMFs belonging to different SMF clusters being different.

5. A method for standby SMF discovery, the method comprising:

the first SMF and the second SMF belong to the same SMF cluster of the same SMF group, SMFs in the same SMF cluster are in a master-slave relationship with each other, manage the same session, and are configured with the same selection parameters.

6. The method of claim 5, wherein the determining a backup SMF based on the information for the second SMF comprises:

7. The method of claim 5, wherein prior to sending the NF discovery request message to the network data warehouse function, NRF, the method further comprises:

8. The method of claim 7, wherein said receiving said selection parameter delivered by said first SMF comprises:

under the condition that the network function node NF is a user plane function entity UPF, receiving an N4session establishment message which is sent by the first SMF and carries the selection parameters;

9. The method of claim 5, wherein the traffic parameter is a Redundant Sequence Number (RSN).

10. A method according to any of claims 5-9, characterized in that one SMF group comprises at least two SMF clusters, the selection parameters of the SMFs belonging to different SMF clusters being different.

11. A method for standby SMF discovery, the method comprising:

12. The method of claim 11, wherein the method further comprises:

13. The method of claim 12, wherein said issuing the selection parameter to a network function node NF of the session comprises:

14. The method of claim 11, wherein the traffic parameter is a Redundant Sequence Number (RSN).

15. A method according to any of claims 11-14, characterized in that one SMF group comprises at least two SMF clusters, the selection parameters of the SMFs belonging to different SMF clusters being different.

16. A network data warehouse functional entity is characterized by comprising a receiving module, an obtaining module, a discovering module and a sending module, wherein the receiving module is used for receiving NF discovery request messages sent by a network functional node NF, and the NF discovery request messages are sent by the NF when a first session management functional entity SMF corresponding to a current session is detected to be in fault;

17. A network function node is characterized by comprising a sending module, a receiving module and a determining module, wherein the sending module is used for responding to the detection of the fault of a first session management function entity (SMF) corresponding to the current session and sending a network function Node (NF) discovery request message to a network data warehouse function entity (NRF), the NF discovery request message carries selection parameters of the first SMF, the selection parameters comprise an identification of an SMF group and service parameters, and the identification of the SMF group is the identification of the group where the first SMF is located;

the determining module is configured to obtain information of a second SMF carried therein, and determine a standby SMF according to the information of the second SMF, where the information of the second SMF is determined by the NRF according to a mapping relationship between the information of the SMF and a selection parameter and the selection parameter; the first SMF and the second SMF belong to the same SMF cluster of the same SMF group, and the SMFs in the same SMF cluster are in a master-slave relationship with each other, manage the same session and are configured with the same selection parameters.

18. A session management functional entity is characterized by comprising a registration module, wherein the registration module is used for sending a network function node NF registration request message to a network data warehouse function entity NRF, the NF registration request message carries selection parameters of the SMF so that the NRF establishes a mapping relation between the information of the SMF and the selection parameters, and the selection parameters comprise an identifier of an SMF group where the SMF is located and service parameters;

the SMF belongs to a SMF cluster in the SMF group, and SMFs in the same SMF cluster are in a master-slave relationship with each other, manage the same session and are configured with the same selection parameters.

19. An electronic device, comprising:

one or more processors;

a storage device having one or more programs stored thereon;

the one or more programs, when executed by the one or more processors, cause the one or more processors to implement the backup SMF discovery method of any of claims 1-15.

20. A computer readable medium having stored thereon a computer program, wherein said program when executed implements the backup SMF discovery method of any of claims 1-15.