WO2020202043A1

WO2020202043A1 - Method for reselection of a network function (nf) service instance of a nf service producer

Info

Publication number: WO2020202043A1
Application number: PCT/IB2020/053115
Authority: WO
Inventors: Magnus HALLENSTÅL; Magnus Olsson; Aldo Bolle; Maria Cruz BARTOLOMÉ RODRIGO
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2019-04-02
Filing date: 2020-04-01
Publication date: 2020-10-08

Abstract

The disclosure relates to methods, computer readable media containing instructions and systems, for reselection of a NF service instance of a selected NF service Producer. The method comprises a Network Function (NF) service Consumer sending a request to the selected NF service Producer indicating an NF service instance associated with a specific service of the selected NF service Producer and the NF service Consumer receiving a response from the selected NF service Producer, the response including a binding indication, the binding indication indicating one or more NF Producer instance for NF service instance reselection of subsequent requests associated with the specific service of the selected NF service Producer.

Description

METHOD FOR RESELECTION OF A NETWORK FUNCTION (NF) SERVICE INSTANCE OF A NF SERVICE PRODUCER

PRIORITY STATEMENT UNDER 35 U.S.C. S.119(E) & 37 C.F.R. S.1.78

[0001] This non-provisional patent application claims priority based upon the prior U.S. provisional patent application entitled“METHOD FOR INDICATING A NETWORK FUNCTION (NF) INSTANCE SELECTION PREFERENCE TO A NF SERVICE CONSUMER”, application number 62/827965, filed April 2^nd, 2019, in the names of HALLENSTAL et al.

TECHNICAL FIELD

[0002] The present disclosure relates to third-generation partnership project (3GPP) Fifth Generation Core Network (5GC) Network Functions (NFs).

BACKGROUND

[0003] 5GC service base architecture has been standardized. For release 16, enhancements to Service Based Architecture (SBA) is studied. One of the

enhancements is the introduction of service sets. A service set is a group of service instances with access to the same data. This means that a consumer accessing a service may choose any service within a service set for all transactions related to a specific User Equipment (UE).

[0004] There is a customer and operator’s interest for improvements to the concept of service set.

[0005] The reader is referred to the 3GPP specification in its entirety, as published before the filing date of the priority document cited above, and more particularly to 3 GPP TS 23.502 V16.0.2 (2019-04).

SUMMARY

[0006] There is provided a method for reselection of a NF service instance of a selected NF service Producer. The method comprises sending a request to the selected NF service Producer indicating an NF service instance associated with a specific service of the selected NF service Producer and receiving a response from the selected NF service Producer, the response including a binding indication, the binding indication indicating one or more NF Producer instance for NF service instance reselection of subsequent requests associated with the specific service of the selected NF service Producer.

[0007] There is also provided a method, for reselection of a F service instance of a selected NF service Producer. The method comprises receiving a request from a NF service Consumer indicating an NF service instance associated with a specific service of the selected NF service Producer and sending a response to the NF service

Consumer, the response including a binding indication, the binding indication indicating one or more NF Producer instance for NF service instance reselection of subsequent requests associated with the specific NF service of the selected NF service Producer.

[0008] There is provided a non-transitory computer readable media having stored thereon instructions for executing any of the steps described herein.

[0009] There is provided a system for reselection of a NF service instance of a selected NF service Producer. The system comprises processing circuitry and a memory, the memory containing instructions executable by the processing circuitry whereby the system is operative to send a request to the selected NF service Producer indicating an NF service instance associated with a specific service of the selected NF service Producer and receive a response from the selected NF service Producer, the response including a binding indication, the binding indication indicating one or more NF Producer instance for NF service instance reselection of subsequent requests associated with the specific service of the selected NF service Producer.

[0010] There is provided a system for reselection of a NF service instance of a selected NF service Producer. The system comprises processing circuitry and a memory, the memory containing instructions executable by the processing circuitry whereby the system is operative to receive a request from a NF service Consumer indicating an NF service instance associated with a specific service of the selected NF service Producer and send a response to the NF service Consumer, the response including a binding indication, the binding indication indicating one or more NF Producer instance for NF service instance reselection of subsequent requests associated with the specific NF service of the selected NF service Producer.

[0011] The methods, non-transitory computer readable media and systems provided herein present improvements to the way methods, non-transitory computer readable media and systems, in 5GC, previously operated. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a schematic illustration of a cellular communications system.

[0013] Figure 2 is a schematic illustration of the 5G System architecture.

[0014] Figure 3 is a schematic illustration of the Non-Roaming 5G System

architecture in reference point representation.

[0015] Figure 4 is a sequence diagram illustrating binding between a Consumer and a Producer.

[0016] Figure 5 is a flowchart of a method, executed by a Network Function (NF) service Consumer, for reselection of a NF service instance of a NF service Producer.

[0017] Figure 6 is a flowchart of a method, executed by a Network Function (NF) service Producer, for reselection of a NF service instance of the NF service Producer.

[0018] Figure 7 is a sequence diagram illustrating an example call flow for flexible selection by a consumer.

[0019] Figure 8 is a schematic illustration of a NF/ Service Set based Service

Framework Architecture.

[0020] Figure 9 is a schematic illustration of a NF/Service Set across Units.

[0021] Figure 10 is a sequence diagram illustrating message exchange between a Consumer Instance and a Producer Instance.

[0022] Figure 11 is a sequence diagram illustrating binding information stored at the Framework Function and its usage.

[0023] Figure 12 is a schematic illustration of a virtualization environment in which the different methods and systems described herein can be deployed.

DETAILED DESCRIPTION

[0024] Various features will now be described with reference to the drawings to fully convey the scope of the disclosure to those skilled in the art.

[0025] Sequences of actions or functions may be used within this disclosure. It should be recognized that some functions or actions, in some contexts, could be performed by specialized circuits, by program instructions being executed by one or more processors, or by a combination of both.

[0026] Further, computer readable carrier or carrier wave may contain an appropriate set of computer instructions that would cause a processor to carry out the techniques described herein. [0027] The functions/actions described herein may occur out of the order noted in the sequence of actions or simultaneously. Furthermore, in some illustrations, some blocks, functions or actions may be optional and may or may not be executed; these are generally illustrated with dashed lines.

[0028] Figure 1 illustrates an example cellular communications system 100. The cellular communications system 100 may be a 5G System (5GS) including a 5G (i.e., a New Radio (NR)) Radio Access Network) RAN including base stations 102-1 and 102-2, which in 5GNR are referred to as NodeBs (gNBs), controlling corresponding macro cells 104-1 and 104-2. The base stations 102-1 and 102-2 are generally referred to herein collectively as base stations 102 and individually as base station 102.

Likewise, the macro cells 104-1 and 104-2 are generally referred to herein collectively as macro cells 104 and individually as macro cell 104. The cellular communications network 100 may also include a number of low power nodes 106-1 through 106-4 controlling corresponding small cells 108-1 through 108-4. The low power nodes 106- 1 through 106-4 can be small base stations (such as pico or femto base stations) or Remote Radio Heads (RRHs), or the like. Notably, while not illustrated, one or more of the small cells 108-1 through 108-4 may alternatively be provided by the base stations 102. The low power nodes 106-1 through 106-4 are generally referred to herein collectively as low power nodes 106 and individually as low power node 106. Likewise, the small cells 108-1 through 108-4 are generally referred to herein collectively as small cells 108 and individually as small cell 108. The base stations 102 (and optionally the low power nodes 106) are connected to a core network 110, which in a 5GS is referred to as a 5G Core (5GC). The base stations 102 and the low power nodes 106 provide service to wireless devices 112-1 through 112-5 in the corresponding cells 104 and 108. The wireless devices 112-1 through 112-5 are generally referred to herein collectively as wireless devices 112 and individually as wireless device 112. The wireless devices 112 are also sometimes referred to herein as UEs.

[0029] In the Fifth Generation Core Network (5GC), service base architecture has been standardized. Figures 2 and 3 are taken from the third-generation partnership project (3GPP) specification, and more particularly from section 4.2.3 of 3GPP TS 23.501 V16.0.2 (2019-04). Figure 2 illustrates the non-roaming reference

architecture, where service-based interfaces are used within the Control Plane. Figure 3 illustrates the 5G System architecture in the non-roaming case, using reference point representation showing how various network functions interact with each other.

[0030] Figures 2 and 3 illustrate wireless communication systems represented as a 5G network architecture composed of core Network Functions (NFs), where interaction between any two NFs is represented by a point-to-point reference point/interface. Figures 2 and 3 can be viewed as one particular implementation of the system 100 of Figure 1, in which embodiments described herein may be implemented.

[0031] Seen from the access side, the 5G network architecture shown in Figure 3 comprises a plurality of UEs connected to either a RAN or an Access Network (AN) as well as an Access and Mobility Management Function (AMF). Typically, the RAN comprises base stations, e.g. such as eNBs or gNBs or similar. Seen from the core network side, the 5G core NFs shown in Figure 3 include a Network Slice Selection Function (NSSF), an Authentication Server Function (AUSF), a Unified Data

Management (UDM), an AMF, a Session Management Function (SMF), a Policy Control Function (PCF), and an Application Function (AF). Reference point representations of the 5G network architecture are used to develop detailed call flows in the normative standardization. The N1 reference point is defined to carry signaling between the UE and AMF. The reference points for connecting between the AN and AMF and between the AN and UPF are defined as N2 and N3, indicated by the letter “N” followed by the name of the NF, e.g. Namf for the service based interface of the AMF and Nsmf for the service based interface of the SMF, etc. The Network

Exposure Function (NEF) and the Network Repository Function (NRF) in Figure 2 are not shown in Figure 3. However, it should be clarified that all NFs depicted in Figure 3 can interact with the NEF and the NRF of Figure 2 as necessary, though not explicitly indicated in Figure 3.

[0032] Some properties of the NFs shown in Figures 2 and 3 may be described in the following manner. The AMF provides UE-based authentication, authorization, mobility management, etc. A UE, even using multiple access technologies, is basically connected to a single AMF because the AMF is independent of the access technologies. The SMF is responsible for session management and allocates Internet Protocol (IP) addresses to UEs. It also selects and controls the UPF for data transfer.

If a UE has multiple sessions, different SMFs may be allocated to each session to manage them individually and possibly provide different functionalities per session. The AF provides information on the packet flow to the PCF responsible for policy control in order to support Quality of Service (QoS). Based on the information, the PCF determines policies about mobility and session management to make the AMF and SMF operate properly. The AUSF supports authentication function for UEs or similar and thus stores data for authentication of UEs or similar while the UDM stores subscription data of the UE. The Data Network (DN), not part of the 5G core network, provides Internet access or operator services and similar.

[0033] A NF may be implemented either as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, or as a virtualized function instantiated on an appropriate platform, e.g., a cloud infrastructure.

[0034] For release 16 of the 3GPP specification, enhancements to Service Based Architecture (SBA) is studied. One of the enhancements is to introduce service sets. A service set is a group of service instances with access to the same data. This means that a consumer accessing the service may choose any service within a service set for all transactions related to a specific User Equipment (UE).

[0035] In 5G, the former Network Functions (NFs) of previous generations are divided into Services (functionalities). In the context of the present specification,

“NF” and“service” may be used interchangeably and generally mean NFs as services. The services offer an Application programming interface (API), such as HyperText Transfer Protocol (HTTP) or Representational State Transfer (REST), for interacting with other services. . That interaction between services is done by means of one or multiple operations, that can be either of type request/response or subscribe/notify, for example. From an operation perspective a NF service may be either a consumer or a producer. The consumer always needs to use an operation to access or use the service of a producer and vice versa.

[0036] Figure 4 illustrates binding between a NF service Consumer and a NF service Producer.

[0037] Direct Communication or Indirect Communication procedures may be used between the Consumer and Producer. In the case of Indirect Communication, a service communication proxy (SCP), not illustrated, is located between the Consumer and Producer.

[0038] When the Consumer communicates with the Producer, the Producer may return a binding information to the Consumer. The Consumer stores the received binding information. Based on the received binding information the binding is established with a set of Producer instances, optionally in a specific location, or with the specific Producer instance.

[0039] If direct Communication is used, the Consumer selects the NF Service Producer and sends the request to the selected NF Service Producer. If indirect Communication mode is used the NF Service Consumer sends the request to the SCP and provides within the service request to the SCP the discovery and selection parameters necessary to discover and select a NF Service Producer.

[0040] The NF Service Producer sends a response to the NF Service Consumer. In the response the NF Service Producer may include a resource address with a binding information. If the NF Service Consumer receives a resource address, it uses it for subsequent requests regarding the concerned resource. Otherwise, the procedure ends here.

[0041] The resource address includes a binding either with a set of NF Service Producers, optionally for a given Location, or with the specific NF Service Producer.

[0042] The NF Service Consumer uses the indicated binding information received in the previous step for subsequent requests regarding the concerned resource(s). The following applies when the NF Service Producer is selected.

[0043] In the case where the binding is established with the NF Service Producer, the indicated NF Service Producer is selected. If the indicated NF Service Producer becomes unavailable, a different NF Service Producer within the same set of NF Service Producers is selected.

[0044] In the case where the binding is established with a set of NF Service

Producers, one of the NF Service Producers from the indicated set of NF Service Producers is selected.

[0045] In the case where the binding is established with a set of NF Service Producers for a given Location, one of the NF Service Producers from the indicated set of NF Service Producers corresponding to the Location is selected.

[0046] The Producer sends a response to the Consumer. The Producer may respond with an updated resource address different from the one received in the previous response.

[0047] The document 3GPP TS 23.502 V16.0.2 (2019-04) provides examples of services that can be produced and consumed, such as AMF services, under section 5.2.2. [0048] One such example service has a service operation name

Namf_Communication_NlN2MessageTransfer. The service has for description: CN NF request to transfer downlink N1 and/or N2 message to the UE and/or AN through the AMF. Input and output are described in terms of required and optional. Input, Required: CN NF identifier (ID), Message type (N1 or N2 or both), Message

Container(s) where at least one of the message containers (N1 or N2) is required. Input, Optional: last message indication, Session ID, Paging Policy Indicator, Address Resolution Protocol (ARP), Area of validity for the N2 SM information, 5QI, NlN2TransferFailure Notification Target Address, type of N2 SM information.

Output, Required: Result indication. Output, Optional: Redirection information.

[0049] Consumers and Producers are logical entities that can run on different physical entities depending on the implementation to provide services such as the service described previously. Consumers and Producers take the form of logic, Software (SW), processing entity that execute or process the business or application logic that is able to provide the expected functionality or service. The business or application logic, in turn, may run in a virtual machine or container or any equivalent or variant thereof known in the art, that can be hosted in a VNF, in a Data Center or any other virtual or physical environment.

[0050] Examples of consumer NF or services include Unified Data Management (UDM), Policy Control Function (PCF), Network Exposure Function (NEF), Session Management Function (SMF), to name only a few.

[0051] Each NF (e.g. UDM, PCF, NEF, SMF...) generally includes multiple services, that uses multiple operations to interact with other services. What defines what is a “consumer” or a“producer” is in fact the operation that is executed at a given time. A given NF may be considered a consumer when executing an operation and then it may be considered a producer when executing another operation. A given NF may be considered a consumer in relation with a first NF and a producer in relation with a second NF. The same NF is, in both cases, both consumer and producer. That means that a service may be a producer and a consumer. For each service, there may be a producer instance and a consumer instance of the same service, where the producer and consumer instances are different NF instances.

[0052] The Consumers and producers may be used in the Service Based Architecture, with entities having Service Based Interfaces, the API, that are structured in services with operations. [0053] There is a customer and operator’s interest to allow the consumer to have the flexibility to either keep using (be sticky) to a certain service producer instance or be allowed to reselect an alternative instance within the service Set. This is to allow the consumer behaviour to be dynamically changed.

[0054] One outcome of allowing this is having a better workload balance within the different service instances.

[0055] There was previously no solution provided in 3GPP TS documents for flexible selection. It was only described that the Network Function (NF) Producer registers in the Network Repository Function (NRF) an indication whether the NF/service instances are part of an NF Set/service Set.

[0056] Figure 5 illustrates a method 500 for reselection of a NF service instance of a selected NF service Producer, comprising sending, step 503, a request to the selected NF service Producer indicating an NF service instance associated with a specific service of the selected NF service Producer; and receiving, step 504, a response from the selected NF service Producer, the response including a binding indication, the binding indication indicating one or more NF Producer instance for NF service instance reselection of subsequent requests associated with the specific service of the selected NF service Producer.

[0057] The binding indication indicating one or more NF Producer instance may indicate a NF service instance, a NF instance, a NF service set, or a NF set. The binding indication indicating one or more NF Producer instance may comprises a NF service instance identifier (ID), a NF instance ID, a NF service set ID, or a NF set ID.

[0058] A Service Communication Proxy (SCP) may be located between a NF service Consumer and the selected NF service Producer and the request and response may be sent from the NF service Consumer to the SCP and from the SCP to the selected NF service Producer and the response may be sent from the selected NF service Producer to the SCP and from the SCP to the NF service Consumer. The NF service instance reselection may be made, by the NF service Consumer or by the SCP, within a NF service set. The method may further comprise sending, step 501, a NF discovery request to a Network Repository Function (NRF); and receiving, step 502, a response comprising NF profiles of NF service instances comprised in the NF service set matching the Request. The NF service instance reselection may be made for load balancing between different NF service instances of the NF service Producer. [0059] Alternatively, in addition or in combination, the method for reselection of a NF service Producer instance of a selected NF service Producer comprises sending a request to the NF service Producer instance; and receiving a response from the NF service Producer instance, the response including a binding indication, the binding indication indicating one or more NF Producer instance for NF service Producer instance reselection of subsequent requests associated with a specific NF service of the NF service Producer.

[0060] Figure 6 illustrates a method 600 for reselection of a NF service instance of a selected NF service Producer, comprising receiving, step 601, a request from a NF service Consumer indicating an NF service instance associated with a specific service of the selected NF service Producer; and sending, step 602, a response to the NF service Consumer, the response including a binding indication, the binding indication indicating one or more NF Producer instance for NF service instance reselection of subsequent requests associated with the specific NF service of the selected NF service Producer.

[0061] The binding indication indicating one or more NF Producer instance may indicate a NF service instance, a NF instance, a NF service set, or a NF set. The binding indication indicating one or more NF Producer instance may comprises a NF service instance identifier (ID), a NF instance ID, a NF service set ID, or a NF set ID.

[0062] A Service Communication Proxy (SCP) may be located between the NF service Consumer and the NF service Producer and the request and response may pass through the SCP. The NF service instance reselection may be made, by the NF service Consumer or by the SCP, within a NF service set. The NF service instance reselection may be made for load balancing between different instances of the NF service Producer.

[0063] Alternatively, in addition or in combination, the method for reselection of a NF service Producer instance of a selected NF service Producer, comprises receiving a request from a NF service Consumer; and sending a response to the NF service Consumer, the response including a binding indication, the binding indication indicating one or more NF Producer instance for NF service Producer instance reselection of subsequent requests associated with a specific NF service of the NF service Producer.

[0064] Therefore, a new parameter is proposed (that could take the form of a flag, data field, structure or any other suitable alternative) in the operation response (from a producer to a consumer, with optionally an intermediate Service Communication Proxy (SCP)), that informs the consumer whether the producer has a preference for the consumer or SCP to keep using an identified resource in the response (it includes a Location with a Resource ID), or alternatively if the consumer should reselect, i.e. choose another instance within the Set.

[0065] Proposed behavior in operation response may be included according to different scenarios, one of which being only ad-hoc, i.e. only when the producer requests the consumer to consider a different preferred behavior, or, according to an alternate scenario, proposed behavior in operation response could be included all the time or could be included based on other criteria.

[0066] The proposed methods allow the producer to indicate a preference to the consumer (and to the SCP in indirect communication) with respect to whether to reselect instances within the Set, or alternatively to use the same producer instance for subsequent requests.

[0067] Figure 7 illustrates an example call flow for flexible selection by a consumer.

[0068] A prerequisite for the flow of Figure 7 is that the service B has discovered service A using the discovery service of the Network Repository Function (NRF). In the discovery response it is indicated whether or not instances of service A is part of a service set.

[0069] The NRF supports the following functionalities. The NRF supports service discovery function, receive NF Discovery Request from NF instance or SCP, and provides the information of the discovered NF instances (discovered) to the NF instance or SCP. The NRF maintains the NF profile of available NF instances and their supported services. NF profile of NF instance maintained in an NRF includes various information, some of which being listed here: NF instance ID, NF type, Fully Qualified Domain Name (FQDN) or Internet Protocol (IP) address of the NF, NF capacity information, NF priority information, NF Set ID, NF Service Set ID of the NF service instance, etc.

[0070] In the context of Network Slicing, based on network implementation, multiple NRFs can be deployed at different levels, such as Public Lan Mobile Network (PLMN) level, shared-slice level), slice-specific level.

[0071] Further, before continuing with the description of Figure 7, and to exemplify some of the concepts described herein, some information concerning how NF/service and service set work, according to 3GPP, is provided in relation with figures 8 to 11, which are taken from the 3GPP specification, 3GPP TR 23.742 V16.0.0 (2018-12), along with related explanations provided in the following paragraphs.

[0072] Figure 8 illustrates NF/Services grouped into NF/Service Sets. Within one NF/Service Set, the capability of each NF/service Instance is the same. One

NF/Service Set can be deployed across Data Centers (DCs). Each NF/service set has one globally unique identity. The NF/Service instances are deployed in Units. Each Unit shares the same platform function and includes one or multiple NF/Service sets, which can be same or different NF/Service types, and a Service Framework. A unit is located within one DC. The NF/Service instances within a Unit may not expose to services outside of the Unit. The Framework Function provides functions like regi strati on/discovery of internal service instances for internal service management, regi strati on/discovery with NRF for outside communication, communication between internal NF/Service instances and outside the Unit, load balance among service instances connected to it, etc. It is built on top of the existing service Frameworks Function. It is also possible that the NF/Service instances within the Unit

communicate with outside directly without going through the Framework Function.

[0073] Turning to figure 9, one NF/Service set is composed by the NF/Service instances located at the same or different Units. NF/Service instances within a NF/Service set share the same set of data. If the NF/Service instance does not expose to service outside of the unit, it only registers to the Framework Function. If the NF/Service instance wants to expose service outside, besides the registration to the Framework Function, the NF/Service Instance is also registered to the NRF via the standardized interface. When the NF/service instance is registered to NRF, depend on whether or not it wants to be accessed directly, the information registered in NRF is different. If the NF/service instance is hidden toward outside, the set ID of the service instance and the Unit address pointing to the Framework Function are registered to NRF. On the contrary, if the service instance is directly registered to the NRF, i.e. no service instance hiding, the service instance and the Unit address pointing to the service instance itself are registered to NRF. For each registered address at NRF it is associated with one weight factor, which reflect the capacity of the NF/service instance associated with the registered address. When one NF/Service Set is deployed across several DCs, the Unit Address associated with each DC are registered in NRF.

[0074] When a consumer initiates communication, it first invokes service discovery. In case the Framework Function is used, the producer set ID together with Unit address pointing to Framework Function are provided to the consumer in the service discovery response. The consumer can initiate communication with producer by including the producer set ID in the message and send the message to the indicated Unit address which points to the Framework Function. The Framework Function selects producer instances based on the producer set ID and the previously registered NF/Service instance. Thus, the Load balancing is achieved by the Framework Function. In case the Framework Function is not used, the NF/Service Set ID and Instance Pointer, together with Unit address pointing to Instance address, are provided to the consumer in the service discovery response. It is same as the Rel-15 NF/Service discovery procedure. If the NF/Service Set is spread across DCs, the weight factor of each Unit address is also returned to the consumer, and the consumer selects a Unit address based on the weight factor associated with it and other parameters, e.g.

proximity.

[0075] Figure 10 illustrates message exchange between a Consumer Instance and a Producer Instance, where the Consumer Instance/Producer Instance is assumed to be a Service. In step 1001, the Service Consumer Instance initiates Service Discovery. The message is sent to NRF. The request includes the parameters to find the Service Producer Instance, e.g. service set type, location info, and depending on service set type, some service specific info may also be included. If the Discovery message is relayed via the framework function and the producer service can be found locally, the framework function responds to the consumer directly without invoking discovery service toward the NRF. In step 1002, in the service discovery response, the service producer service set ID and the Unit address are returned to the consumer instance. In step 1003, the Consumer constructs a request message which includes the Service Producer set ID information received in step 1002 and sends the message to the Unit address received in step 1002. Depending on the type of the Unit address, i.e. pointing to the registered instance or framework function, the message may be sent directly to a producer instance or to an entity within the Unit, e.g. Framework Function, which chooses producer instance and forwards the message to the producer instance. In step 1004, the producer handles the request message, and sends response message to consumer instance.

[0076] The NF/Service Set ID is registered to the NRF. However, the NF/Service Set can be regarded as Rel-15 NF Instance. The NRF does not need to differentiate whether it is a NF/Service Set or a NF Instance, no impact on the NRF. Each NF/NF Service Set may be associated with one, or multiple Unit addresses together with an associated weight factor. When the NRF selects a Unit address, the weight factor is taken into account. NF/Service Registration management, for each NF/Service instance, registers to the Framework Function and optionally registers to the NRF.

The Framework Function is aware of the addition, removal or failover of NF/Service instances within the Unit. Based on the registered NF/Service profile the Framework Function or NRF can authorize the access to the service of the Producer. By separating the whole discovery procedure into two steps, i.e. NF/Service Set

Discovery and Instance selection, the Service Framework Function does not need to understand the business service logic related discovery strategies, which involves parameters used for services discovery, and the related discovery failure handling.

Also, the consumer does not need to be aware of the status of the provider Instance, e.g. scaling in/out. When the message is routed via the Framework Function, the Framework Function always routes the message based on the NF/Service Set ID and Unit address. One simple and unified routing mechanism can be used. The

Framework Function manages the NF/Service Instance. The NF/Service context is shared among the NF/Service Instance within the same NF/Service Set. The Instances within the same set are replaceable with each other, thus a change of the NF/Service Instance need not be notified to the peer NF/Service instances.

[0077] From the above, it can be seen that any change of the Provider Service Instance, e.g. scaling in/out, does not impact the Consumer Service Instance. The Framework Function is responsible for NF/Service instance selection for the communication between NF/Service instances. Hence, the NF/Service instance can focus on business logic. Also, the Framework function routes the messages using the same mechanism.

[0078] When one Service Instance communicates with another Service Instance, it includes the binding ID information, which is generated by the service producer. The Service Consumer instance stores the received binding ID until the UE context is released. The binding information, i.e. the binding between the binding ID and service instance, is stored in a new functional module within the Service Framework where the service producer is deployed. When the binding is changed, e.g., the service instance is scaling in/out or failure, the communication peer does not need to be aware. Thus, high reliability can be reached if the service instance to be

communicated is replaced, e.g. due to failure. [0079] Similar as the definition of the AMF Instance at Rel-15, it is assumed that the service instance is identified by a Service Set ID and Instance Pointer. When the Service Producer Instance is communicated per the Service Consumer request, the Service Producer Instance provides a binding identifier (i.e. binding ID) and returns it to the Service Consumer. The Service Consumer use the binding ID to identify the Producer Instance to be contacted. Two types of bindings ID are defined. Service Set ID based, bind to a service set and is not limited to a dedicated Instance. Service Set ID and Instance Pointer based. Depending on the meaning of the binding ID, it can be bound to a specific service instance but the service instance can be replaced, or only to one dedicated Instance.

[0080] The Service Consumer instance stores the received binding ID until the UE context is released and includes it in the following request targeted to the same Producer Service. When the message reaches the Unit where the service producer instance is located, it is routed to a service producer instance based on the binding ID included in the message. The binding between the binding ID and a service producer instance is stored within the Unit, e.g. framework function. The service producer instance may change, while the binding ID exposed to the Service Consumer remains the same. In that case, different transactions may reach to different Service Instance even using the same binding ID.

[0081] The UE context is shared among the NF/Service Instance within the same NF/Service set. If one NF/Service Instance fails, the message targeting to the failed NF/Service Instance is routed to another NF/Service Instance within the same NF/Service set. The replacing NF/Service Instance retrieve the UE contexts to handle the incoming message. Thus, a high reliability can be achieved.

[0082] Figure 11 illustrates how the binding ID is exchanged between the consumer and producer, and how the message is routed based on the binding ID.

[0083] The binding between the service instance and the binding ID is maintained within a Unit, e.g. by the Framework Function. As an example, the binding can be established when the service instance is started, e.g. as part of the service instance registration procedure. The Service Framework includes a function module which stores the following information: the Service Set ID, Instance Pointer and IP address. Thus, no matter which type of binding ID is used by the service instance later, the Function in the Unit, e.g. Framework Function, can always route the message to the service instance. The service instance indicates the assigned binding ID to the Service Framework at the registration procedure, and the Service Framework stores the assigned binding ID. The steps of the binding ID exchange between the consumer and producer is now explained. In step 1101, the consumer allocates a binding ID, which is related to the service consumer and used for following transaction request from the peer service instance and includes this information in the message sent to the producer. If the following transaction request from the peer side is preferred to be handled by any instance within the same service consumer set, the binding ID is Service Set ID based. If the following transaction request from the peer side is preferred to be handled by this instance, the binding ID is a Service Set ID and Instance Pointer based. In step 1102, the Function in the Unit, e.g. the framework function, selects the producer instance based on the previously stored association of binding ID and instance ID. In step 1103, the Message 1 is forwarded to the selected producer instance. In step 1104, the producer instance provides a producer's binding ID to the consumer instance in response message. The type of binding ID allocated is similar as the step 1101. In step 1105, the response message is forwarded to the Consumer. The Consumer stores the received Producer's binding ID as part of the UE context.

[0084] The steps 1106-1108 concern binding ID usage for the following transaction. In step 1106, the consumer sends message 2, including producer's binding ID received at step 1105. In step 1107, if the producer's binding ID allocated at step 1104 is the Service Set ID and Instance pointer based, Producer 1 is selected based on producer's binding ID. If the producer's binding ID allocated at step 1104 is Service Set ID based, the Function in the Unit, e.g. the framework function, re-selects the producer instance. The re-selected producer instance may be different comparing to the Producer 1. In that case if the transaction needs to be routed to the same Producer Instance for following transaction, another information needs to be provided, e.g. a different binding information which is called temporary binding ID is used. In step 1108, message 2 is forwarded to Producer 1.

[0085] Step 1109 concerns binding information update. In step 1109, the binding between the binding ID and Producer 1 is released, e.g. due to a deregistered producer instance or during scale in/out.

[0086] The steps 1110-1114 concern message handling after the binding information is released. In step 1110, the consumer sends Message 3 which include the producer's binding ID provided by Producer 1. In step 1111, since there is no producer instance associated with the binding ID, but the binding ID includes the Service Set ID information, a new producer instance is selected based on Producer service set ID and optional preconfigured rules. In step 1112, message 3 is forwarded to Producer 2. In step 1113, the Producer 2 retrieve the UE context and provides a new producer's binding ID which is associated with producer 2 or this Set. In step 1114, the response message is forwarded to the Consumer.

[0087] Returning to Figure 7, an example call flow for flexible selection by a consumer is now described. In step 701, Service B sends an operation request to Service A, that is a producer. On the right-hand side, there is a Set of NF instances, labelled NF-X Setl, comprising NF-X instance 1 and NF-X instance N, having access to the same Storage Resource. Service B, to be able to send this operation, first need to get from the NRF available NF instances for the NF type/service type that is requested, and then select an NF instance. In this example, NF-X instance 1 is selected.

[0088] In step 702, a response is received from Service A. The response comprises the inclusion of, as a new indication, a preference with respect to whether the consumer should use the same producer instance for subsequent requests, or, alternatively, reselect instances within the Set. The indication can take the form of a Flag: instance selection preference, which indicate whether to use the same producer instance or to reselect instances.

[0089] In step 703, the Consumer checks this new indication, i.e. the binding indication. In this example, the preference (or Flag: instance selection preference) indicates to keep using the same selected instance. In step 704, an operation is sent to the same instance as before, according to the indication received. In step 705, no new indication is included in the response. In step 706, the Consumer checks if the new indication is included. In this example, it is considered that the indication is not included, then the consumer should keep the same behavior indicated for the last indication received. That is, keep using the same instance. In step 707, an Operation is sent to the same instance as before. In step 708, in this particular example, it is considered that now the producer includes again the new indication. The indication (i.e. the binding indication) takes the form of a Flag: instance selection preference, which indicate whether to use the same producer instance or to reselect instances. In step 709, the consumer checks the indication, that in this example is to change the behavior, and then start selecting within the Set, instead of keep using the same instance. In step 710, the Consumer sends the operation to any instance within the service Set, according to the indication. In this case the service B selects service instance N, NF-X instance N. In step 711, a Response is sent back in this case without an indication. In step 712, the Consumer checks if the new indication is included. In this example it is considered that the indication is not included, then the consumer should keep the same behavior as indicated by the last indication received. That is, keep reselecting within the Set. In step 713, the Consumer sends the operation to any service instance in the service set. The instance within the Set may be selected by different means, it is not precluded that the same instance may be selected (e.g. if reselection is based on load criteria). In step 714, a Response is sent back, in this case, without an indication.

[0090] It should be noted that, in case of indirect communication via an SCP, the consumer should pass any received indication to the SCP to allow the SCP to perform the same behavior as the Consumer. As a clarifying note, when an operation is sent to an instance, the instance executes the operation and sends the indication with the response. This indication will then be used for deciding to which instance to send the next operation. It could be envisioned that, in some alternate implementation, if the instance currently selected is unable to execute (or timely execute) the operation, it sends the indication to reselect with the response and the operation is sent to a reselected instance instead (e.g. the reselected instance has a lower workload and can timely execute the operation).

[0091] The following paragraphs describe how 3GPP TS 23.502 V16.0.2 (2019-04) can be modified. In 23.502, clause 4.17.12.2, the following can be read under step 3: The NF Service Consumer uses the indicated binding information received in the previous step for subsequent requests regarding concerned resource. The following applies when the NF Service Producer is selected:

In the case of the binding is established with the NF Service Producer, the indicated NF Service Producer is selected. If the indicated NF Service Producer becomes unavailable, a different NF Service Producer within the same service set of NF Service Producers is selected.

In the case of the binding is established with a service set of NF Service Producers, one of the NF Service Producers from the indicated service set of NF Service Producers is selected. In the case of the binding is established with a service set of NF Service Producers for a given Location, one of the NF Service Producers from the indicated service set of NF Service Producers corresponding to the Location is selected.

[0092] In the second bullet, it is assumed that the consumer somehow gets some information that the resource binding is towards a service set. It is unclear how this knowledge is achieved. Three possibilities have been identified:

[0093] 1) The resource address received is associated with the service set. In the case of interworking with Rel-15 it is unclear how a Rel-15 consumer would behave, since it has no knowledge of a service set, and has no way of using the address referring to a service set. Thus, this is a non-backwards compatible solution. Also, it is unclear how a Rel-16 would know that the resource address is referring to a service set unless NF profile includes also a service set address.

[0094] 2) The resource address point to a specific resource (an address and a resource identifier, e.g. SM context ID), and the producer also provides a service set id in the response. In this case, a Rel-15 consumer would ignore the service set id received and just use the selected resource, but a Rel-16 consumer may select any service instance within the service set.

[0095] 3) Similar as 2), but instead of sending the service set id in a response, the consumer gets the service set information in the NF profile. In this case a Rel-15 consumer would just use the resource address, but a Rel-16 consumer would know that a selected service was associated with a service set, so any service instance can be used in subsequent requests.

[0096] A resource address has the following contents: network address (FQDN, IP address), path, and resource identifier (e.g. SM context ID) see 3GPP TS 29.500 for the structure of resource URL If a service instance is within a service set and consumer chooses to select another service instance, the consumer needs to construct a resource address for the new service instance. This is done by adding the resource identifier to the network address and path of the newly selected service instance.

[0097] When the consumer selects a service instance in a service set, it can add the resource ID to the selected service instance’s network address and path.

[0098] The third bullet from cited text of clause 4.17.12.2 above seems to imply that a location is passed in a response to a request. This could be a possible solution, but since it is proposed to have location in NF profile on a per service instance, the consumer would know what location it selected, and could continue to use this location as preference if selecting another service instance than what is sent back by the producer.

[0099] It is also proposed that a consumer uses the location at service instance level in the NF profile for the selected service instance if using another service instance in subsequent requests than what was received in a response.

[00100] Figure 12 is a schematic block diagram illustrating a virtualization environment 1200 in which some functions may be implemented. As used herein, virtualization can be applied to a node (e.g., a virtualized base station or a virtualized radio access node) or to a device (e.g., a UE, a wireless device or any other type of communication device) and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components (e.g., via one or more applications, components, functions, virtual machines or containers executing on one or more physical processing nodes in one or more networks).

[00101] In some embodiments, some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines or containers implemented in one or more virtual environments 1200 hosted by one or more of hardware nodes 1230. Further, in embodiments in which the virtual node is not a radio access node or does not require radio connectivity (e.g., a core network node), then the network node may be entirely virtualized.

[00102] The functions may be implemented by one or more applications 1220 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) operative to implement steps of some methods according to some embodiments. The NFs, or services, or the instances of the NF service Consumer and NF service Producer may be implemented as the applications/instances 1220. Applications 1220 run in virtualization

environment 1200 which provides hardware 1230 comprising processing circuitry 1260 and memory 1290. Memory 1290 contains instructions 1295 executable by processing circuitry 1260 whereby application 1220 is operative to provide any of the relevant features, benefits, and/or functions disclosed herein.

[00103] Virtualization environment 1200, comprises general-purpose or special-purpose network hardware devices 1230 comprising a set of one or more processors or processing circuitry 1260, which may be commercial off-the-shelf (COTS) processors, dedicated Application Specific Integrated Circuits (ASICs), or any other type of processing circuitry including digital or analog hardware components or special purpose processors. Each hardware device may comprise memory 1290-1 which may be non-persistent memory for temporarily storing instructions 1295 or software executed by the processing circuitry 1260. Each hardware devices may comprise one or more network interface controllers 1270 (NICs), also known as network interface cards, which include physical network interface 1280. Each hardware devices may also include non-transitory, persistent, machine readable storage media 1290-2 having stored therein software 1295 and/or instruction executable by processing circuitry 1260. Software 1295 may include any type of software including software for instantiating one or more virtualization layers 1250 (also referred to as hypervisors), software to execute virtual machines 1240 or containers as well as software allowing to execute functions described in relation with some embodiments described herein.

[00104] Virtual machines 1240 or containers, comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer 1250 or hypervisor. Different embodiments of the instance of virtual appliance 1220 may be implemented on one or more of virtual machines 1240 or containers, and the implementations may be made in different ways.

[00105] During operation, processing circuitry 1260 executes software 1295 to instantiate the hypervisor or virtualization layer 1250, which may sometimes be referred to as a virtual machine monitor (VMM). Virtualization layer 1250 may present a virtual operating platform that appears like networking hardware to virtual machine 1240 or to a container.

[00106] As shown in Figure 12, hardware 1230 may be a standalone network node, with generic or specific components. Hardware 1230 may comprise antenna 12225 and may implement some functions via virtualization. Alternatively, hardware 1230 may be part of a larger cluster of hardware (e.g. such as in a data center or customer premise equipment (CPE)) where many hardware nodes work together and are managed via management and orchestration (MANO) 12100, which, among others, oversees lifecycle management of applications 1220.

[00107] Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high-volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

[00108] In some embodiments, one or more radio units 12200 that each include one or more transmitters 12220 and one or more receivers 12210 may be coupled to one or more antennas 12225. Radio units 12200 may communicate directly with hardware nodes 1230 via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station.

[00109] In some embodiments, some signaling can be effected with the use of control system 12230 which may alternatively be used for communication between the hardware nodes 1230 and the radio units 12200.

[00110] The non-transitory computer readable media 1290-2 has stored thereon instructions for executing any of the methods described herein.

[00111] The system 100 or 1200 is operative to reselect a NF service instance of a NF service Producer. The system comprises processing circuitry e.g. 1260 and a memory e.g. 1290. The memory contains instructions executable by the processing circuitry whereby the system is operative to send a request to the selected NF service Producer indicating an NF service instance associated with a specific service of the selected NF service Producer and receive a response from the selected NF service Producer, the response including a binding indication, the binding indication indicating one or more NF Producer instance for NF service instance reselection of subsequent requests associated with the specific service of the selected NF service Producer.

[00112] The binding indication indicating one or more NF Producer instance may indicate a NF service instance, a NF instance, a NF service set, or a NF set. The binding indication indicating one or more NF Producer instance may comprises a NF service instance identifier (ID), a NF instance ID, a NF service set ID, or a NF set ID.

[00113] In the system, a Service Communication Proxy (SCP) may be located between the NF service Consumer and the selected NF service Producer and the request may be sent from the NF service Consumer to the SCP and from the SCP to the selected NF service Producer and the response may be sent from the selected NF service Producer to the SCP and from the SCP to the NF service Consumer. The NF service instance reselection may be made, by the NF service Consumer, within a NF service set. The NF service instance reselection may be made, by the SCP, within a NF service set. The system may be further operative to send a NF discovery request to a Network Repository Function (NRF); and receive a response comprising NF profiles of NF service instances comprised in the NF service set matching the Request. The NF service instance reselection may be made for load balancing between different NF service instances of the NF service Producer.

[00114] The system 100 or 1200 is operative to reselect a NF service instance of the NF service Producer. The system comprises processing circuitry e.g. 1260 and a memory e.g. 1290. The memory contains instructions executable by the processing circuitry whereby the system is operative to receive a request from a NF service Consumer indicating an NF service instance associated with a specific service of the selected NF service Producer and send a response to the NF service Consumer, the response including a binding indication, the binding indication indicating one or more NF Producer instance for NF service instance reselection of subsequent requests associated with the specific NF service of the selected NF service Producer.

[00115] The binding indication indicating one or more NF Producer instance may indicate a NF service instance, a NF instance, a NF service set, or a NF set. The binding indication indicating one or more NF Producer instance may comprises a NF service instance identifier (ID), a NF instance ID, a NF service set ID, or a NF set ID.

[00116] In the system, a Service Communication Proxy (SCP) may be located between the NF service Consumer and the selected NF service Producer and the request may be sent from the NF service Consumer to the SCP and from the SCP to the selected NF service Producer and the response may be sent from the selected NF service Producer to the SCP and from the SCP to the NF service Consumer. The NF service instance reselection may be made, by the NF service Consumer, within a NF service set. The NF service instance reselection may be made, by the SCP, within a NF service set. The NF service instance reselection may be made for load balancing between different instances of the NF service Producer.

[00117] Modifications will come to mind to one skilled in the art having the benefit of the teachings presented in the foregoing description and the associated drawings. Therefore, it is to be understood that modifications, such as specific forms other than those described above, are intended to be included within the scope of this disclosure. The previous description is merely illustrative and should not be considered restrictive in any way. The scope sought is given by the appended claims, rather than the preceding description, and all variations and equivalents that fall within the range of the claims are intended to be embraced therein. Although specific terms may be employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. A method for reselection of a NF service instance of a selected NF service

Producer, comprising:

- sending a request to the selected NF service Producer indicating an NF service instance associated with a specific service of the selected NF service Producer; and

- receiving a response from the selected NF service Producer, the response

including a binding indication, the binding indication indicating one or more NF Producer instance for NF service instance reselection of subsequent requests associated with the specific service of the selected NF service Producer.

2. The method of claim 1, wherein the binding indication indicating one or more NF Producer instance indicates a NF service instance, a NF instance, a NF service set, or a NF set.

3. The method of claim 1, wherein the binding indication indicating one or more NF Producer instance comprises a NF service instance identifier (ID), a NF instance ID, a NF service set ID, or a NF set ID.

4. The method of claim 1, wherein a Service Communication Proxy (SCP) is located between a NF service Consumer and the selected NF service Producer and wherein the request is sent from the NF service Consumer to the SCP and from the SCP to the selected NF service Producer and wherein the response is sent from the selected NF service Producer to the SCP and from the SCP to the NF service Consumer.

5. The method of claim 1, wherein the NF service instance reselection is made, by the NF service Consumer, within a NF service set.

6. The method of claim 4, wherein the NF service instance reselection is made, by the SCP, within a NF service set.

7. The method of claim 1 or 6, further comprising, prior to the step of sending:

- sending a NF discovery request to a Network Repository Function (NRF); and

- receiving a response comprising NF profiles of NF service instances

comprised in the NF service set matching the Request.

8. The method of any one of claims 1 to 7, wherein the NF service instance reselection is made for load balancing between different NF service instances of the NF service Producer.

9. A method for reselection of a NF service instance of a selected NF service

Producer, comprising:

- receiving a request from a NF service Consumer indicating an NF service instance associated with a specific service of the selected NF service Producer; and

- sending a response to the NF service Consumer, the response including a binding indication, the binding indication indicating one or more NF Producer instance for NF service instance reselection of subsequent requests associated with the specific NF service of the selected NF service Producer.

10. The method of claim 9, wherein the binding indication indicating one or more NF Producer instance indicates a NF service instance, a NF instance, a NF service set, or a NF set.

11. The method of claim 9, wherein the binding indication indicating one or more NF Producer instance comprises a NF service instance identifier (ID), a NF instance ID, a NF service set ID, or a NF set ID.

12. The method of claim 9, wherein a Service Communication Proxy (SCP) is located between the NF service Consumer and the selected NF service Producer and wherein the request is sent from the NF service Consumer to the SCP and from the SCP to the selected NF service Producer and wherein the response is sent from the selected NF service Producer to the SCP and from the SCP to the NF service Consumer.

13. The method of claim 9, wherein the NF service instance reselection is made, by the NF service Consumer, within a NF service set.

14. The method of claim 12, wherein the NF service instance reselection is made, by the SCP, within a NF service set.

15. The method of any one of claims 9 to 14, wherein the NF service instance

reselection is made for load balancing between different instances of the NF service Producer.

16. A non-transitory computer readable media having stored thereon instructions for executing any of the methods of claims 1 to 15.

17. A system for reselection of a NF service instance of a selected NF service

Producer, the system comprising processing circuitry and a memory, the memory containing instructions executable by the processing circuitry whereby the system is operative to:

- send a request to the selected NF service Producer indicating an NF service instance associated with a specific service of the selected NF service Producer; and

- receive a response from the selected NF service Producer, the response

18. The system of claim 17, wherein the binding indication indicating one or more NF Producer instance indicates a NF service instance, a NF instance, a NF service set, or a NF set.

19. The system of claim 17, wherein the binding indication indicating one or more NF Producer instance comprises a NF service instance identifier (ID), a NF instance ID, a NF service set ID, or a NF set ID.

20. The system of claim 17, wherein a Service Communication Proxy (SCP) is located between a NF service Consumer and the selected NF service Producer and wherein the request is sent from the NF service Consumer to the SCP and from the SCP to the selected NF service Producer and wherein the response is sent from the selected NF service Producer to the SCP and from the SCP to the NF service Consumer.

21. The system of claim 17, wherein the NF service instance reselection is made, by the NF service Consumer, within a NF service set.

22. The system of claim 20, wherein the NF service instance reselection is made, by the SCP, within a NF service set.

23. The system of claim 17 or 22, wherein the system is further operative to:

- send a NF discovery request to a Network Repository Function (NRF); and - receive a response comprising NF profiles of NF service instances comprised in the NF service set matching the Request.

24. The system of any one of claims 17 to 23, wherein the NF service instance

reselection is made for load balancing between different NF service instances of the NF service Producer.

25. A system for reselection of a NF service instance of a selected NF service

- receive a request from a NF service Consumer indicating an NF service instance associated with a specific service of the selected NF service Producer; and

- send a response to the NF service Consumer, the response including a binding indication, the binding indication indicating one or more NF Producer instance for NF service instance reselection of subsequent requests associated with the specific NF service of the selected NF service Producer.

26. The system of claim 25, wherein the binding indication indicating one or more NF Producer instance indicates a NF service instance, a NF instance, a NF service set, or a NF set.

27. The system of claim 25, wherein the binding indication indicating one or more NF Producer instance comprises a NF service instance identifier (ID), a NF instance ID, a NF service set ID, or a NF set ID.

28. The system of claim 25, wherein a Service Communication Proxy (SCP) is located between the NF service Consumer and the selected NF service Producer and wherein the request is sent from the NF service Consumer to the SCP and from the SCP to the selected NF service Producer and wherein the response is sent from the selected NF service Producer to the SCP and from the SCP to the NF service Consumer.

29. The system of claim 25, wherein the NF service instance reselection is made, by the NF service Consumer, within a NF service set.

30. The system of claim 28, wherein the NF service instance reselection is made, by the SCP, within a NF service set.

31. The system of any one of claims 25 to 28, wherein the NF service instance

32. A method for reselection of a NF service Producer instance of a selected NF

service Producer, comprising:

- sending a request to the NF service Producer instance; and

- receiving a response from the NF service Producer instance, the response including a binding indication, the binding indication indicating one or more NF Producer instance for NF service Producer instance reselection of subsequent requests associated with a specific NF service of the NF service Producer.

33. The method of claim 32, wherein the binding indication indicating one or more NF Producer instance indicates a NF service instance, a NF instance, a NF service set, or a NF set.

34. The method of claim 32, wherein the binding indication indicating one or more NF Producer instance comprises a NF service instance identifier (ID), a NF instance ID, a NF service set ID, or a NF set ID.

35. The method of claim 32, wherein a Service Communication Proxy (SCP) is

located between a NF service Consumer and the selected NF service Producer and wherein the request is sent from the NF service Consumer to the SCP and from the SCP to the selected NF service Producer and wherein the response is sent from the selected NF service Producer to the SCP and from the SCP to the NF service Consumer.

36. The method of claim 32, wherein the NF service instance reselection is made, by the NF service Consumer, within a NF service set.

37. The method of claim 35, wherein the NF service instance reselection is made, by the SCP, within a service set.

38. The method of claim 32 or 35, further comprising, prior to the step of sending:

- sending a NF discovery request to a Network Repository Function (NRF); and - receiving a response comprising NF profiles of NF service Producer instances comprised in the NF service set matching the Request.

39. The method of any one of claims 32 to 38, wherein the NF service instance

40. A method for reselection of a NF service Producer instance of a selected NF

service Producer, comprising:

- receiving a request from a NF service Consumer; and

- sending a response to the NF service Consumer, the response including a binding indication, the binding indication indicating one or more NF Producer instance for NF service Producer instance reselection of subsequent requests associated with a specific NF service of the NF service Producer.

41. The method of claim 40, wherein the binding indication indicating one or more NF Producer instance indicates a NF service instance, a NF instance, a NF service set, or a NF set.

42. The method of claim 40, wherein the binding indication indicating one or more NF Producer instance comprises a NF service instance identifier (ID), a NF instance ID, a NF service set ID, or a NF set ID.

43. The method of claim 40, wherein a Service Communication Proxy (SCP) is

located between the NF service Consumer and the selected NF service Producer and wherein the request is sent from the NF service Consumer to the SCP and from the SCP to the selected NF service Producer and wherein the response is sent from the selected NF service Producer to the SCP and from the SCP to the NF service Consumer.

44. The method of claim 40, wherein the NF service instance reselection is made, by the NF service Consumer, within a NF service set.

45. The method of claim 43, wherein the NF service instance reselection is made, by the SCP, within a NF service set.

46. The method of any one of claims 40 to 45, wherein the NF service instance

47. A non-transitory computer readable media having stored thereon instructions for executing any of the methods of claims 32 to 46.

48. A system for reselection of a NF service instance of a selected NF service

Producer, the system comprising processing circuitry and a memory, the memory containing instructions executable by the processing circuitry whereby the system is operative to execute any of the steps of the method of claims 32 to 46.