Using binding indications between network functions to share resource redundancy information about network function service instances

Abstract

Embodiments herein relate to inputting information related to redundancy. Some embodiments propose a method (400) performed by a first network function (201). The method (400) may include a step (S401) of sending a first message including a first parameter indicating no redundancy to a second network function (202) to indicate that a first context is exclusively bound to a specific network function (NF) service instance within the first network function (201). The specific NF service instance may be identified in a binding indication included in the first message. Embodiments herein may enable an NF service instance to indicate that resources are exclusively bound to this NF service instance, and there is no redundancy for the associated resources.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to PCT Application No. PCT / CN2022 / 106496, entitled "POPULATING THE INFORMATION RELATED TO REDUNDANCY," filed July 19, 2022, the entire contents of which are incorporated herein by reference.

[0002] FIELD Embodiments herein relate generally to the field of mobile communications, and more particularly, embodiments herein relate to inputting redundancy-related information. [Background technology]

[0003] The 3rd Generation Partnership Project (3GPP) from Release 16 (Rel-16) specifies the concept of Network Function (NF) sets to enable service continuity between NF instances within the same NF set. To ensure optimized data replication management, an NF producer may indicate the preferred scope of data replication to peer NFs via binding indications.

[0004] Section 6.12.1 of 3GPP TS 29.500 specifies that "A binding indication shall not be used when a particular resource can only be provided by a specific NF service instance of an NF instance, i.e., when NF service instances of the same NF service cannot share resources within an NF instance. Resources for which no binding or routing binding indication is signaled shall be considered to be exclusively bound to one NF service instance, unless the NF service resource owner instance is part of an NF set (or AMF set) or an NF service set, or unless its NF profile in the NRF indicates that it supports NF service persistence within the NF instance (see clause 6.5 of 3GPP TS 23.527

[38] )." Summary of the Invention

[0005] As specified in TS29.500, for example, the binding indication cannot be used to indicate that a resource is exclusively bound to a specific NF service instance, which may be problematic for some use cases.

[0006] SUMMARY OF THE INVENTION The embodiments herein propose a method, a network function, a computer-readable medium, and a computer program product for inputting no redundancy.

[0007] Some embodiments propose a method performed by a first network function, the method may include sending a first message including a first parameter indicating no redundancy to a second network function to indicate that a first context is exclusively bound to a unique NF service instance within the first network function, the unique service instance may be identified in a binding indication included in the first message.

[0008] In one embodiment, the first message may further include a second parameter indicating a validation timer. The validation timer may indicate a validation period without redundancy.

[0009] In one embodiment, the validation timer may be included in the binding directive or another Hypertext Transfer Protocol (HTTP) header.

[0010] In one embodiment, the first network function may be an NF service producer, and the second network function may be an NF service consumer. Further, the first context may be a resource context, and the first message may be a response message or a notification message.

[0011] In one embodiment, the first network function may be an NF service consumer and the second network function may be an NF service producer. Further, the first context may be a session context or a resource context, and the first message may be a request message or a subscription message.

[0012] In one embodiment, the first network function may act as a home session management function (SMF) for a home-routed packet data unit (PDU) session, and each visited SMF for the home-routed PDU session does not support redundancy.

[0013] In one embodiment, the first network function may be removed from the set of NFs by a service software upgrade, downgrade, or maintenance.

[0014] In one embodiment, a first network function may temporarily lose connectivity to an unstructured data storage function (UDSF) shared by a set of NFs.

[0015] In one embodiment, the method may further include receiving, from the second network function, a second message including a third parameter indicating no redundancy to indicate that the second context is exclusively bound to a unique NF service instance within the second network function. Additionally, the method may further include deleting the second context if the second network function is unavailable.

[0016] Some embodiments propose a method performed by a second network function, the method may include receiving from a first network function a first message including a first parameter indicating no redundancy to indicate that a first context is exclusively bound to a unique NF service instance within the first network function, the unique NF service instance being identified in a binding indication included in the first message.

[0017] In one embodiment, the first message may further include a second parameter indicating a validation timer. The validation timer may indicate a validation period without redundancy.

[0018] In one embodiment, the method may further include deleting the first context if the first network capability is not available.

[0019] In one embodiment, the method may further include deleting the first context if the first network function is not available when the validation timer indicates that the redundancy level is within the validation period.

[0020] In an embodiment, the validation timer may be included in the binding indication or in another HTTP header.

[0021] In one embodiment, the first network function may be an NF service producer, and the second network function may be an NF service consumer. Further, the first context may be a resource context, and the first message may be a response message or a notification message.

[0022] In one embodiment, the first network function may be an NF service consumer and the second network function may be an NF service producer. Further, the first context may be a session context or a resource context, and the first message may be a request message or a subscription message.

[0023] In one embodiment, the first network function may act as a home SMF for a home-routed PDU session, and each visiting SMF for the home-routed PDU session does not support redundancy.

[0024] In one embodiment, the first network function may be removed from the set of NFs by a service software upgrade, downgrade, or maintenance.

[0025] In one embodiment, the first network function may temporarily lose connectivity to a UDSF shared by a set of NFs.

[0026] Some embodiments propose a network function. In one embodiment, the network function may include at least one processor and a non-transitory computer-readable medium coupled to the at least one processor. The non-transitory computer-readable medium may store instructions executable by the at least one processor, such that the at least one processor may be configured to perform any of the above methods. In one embodiment, the network function may be configured as a first network function or a second network function.

[0027] In some embodiments, a computer readable medium is proposed that includes computer readable code that, when run on a device, can cause the device to perform any of the above methods.

[0028] In some embodiments, a computer program product is proposed that includes computer readable code that, when run on a device, can cause the device to perform any of the methods described above.

[0029] Embodiments allow an NF service instance to indicate that resources are bound exclusively to this NF service instance and there is no redundancy for the associated resources using 3gpp-Sbi-Binding-Indication.

[0030] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various embodiments of the present disclosure and, together with the description, serve to further explain the principles of the disclosure and to enable those skilled in the art to make and use the embodiments disclosed herein. In the drawings, like reference numbers indicate equivalent or functionally similar elements. [Brief explanation of the drawings]

[0031] [Figure 1] FIG. 1 is a schematic block diagram illustrating an example architecture for a 5G network architecture in a non-roaming scenario. [Figure 2] 1 is a schematic block diagram illustrating an example architecture of a wireless communication system that indicates additional redundant information. [Figure 3] 1 is a schematic signaling chart illustrating messages in an exemplary procedure for indicating additional redundant information, according to embodiments herein. [Figure 4] 1 is a schematic flowchart illustrating an exemplary method in a first network function, according to embodiments herein. [Figure 5] 10 is a schematic flowchart illustrating an exemplary method in a second network function, according to embodiments herein. [Figure 6] FIG. 2 is a schematic block diagram illustrating an exemplary first network function according to embodiments herein. [Figure 7]FIG. 2 is a schematic block diagram illustrating an exemplary second network function, according to embodiments herein. [Figure 8] FIG. 1 is a schematic block diagram illustrating an exemplary computer-implemented device, according to embodiments herein. DETAILED DESCRIPTION OF THE INVENTION

[0032] Embodiments of the present specification are described in detail below with reference to the accompanying drawings, in which the embodiments are shown. However, these embodiments of the present specification may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Elements of the drawings are not necessarily to scale relative to each other.

[0033] A reference to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described with respect to that embodiment is included in at least one embodiment. Thus, the appearances of the phrase "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment.

[0034] The term "A, B, or C" as used herein means "A" or "B" or "C", the term "A, B, and C" as used herein means "A" and "B" and "C", and the term "A, B, and / or C" as used herein means "A", "B", "C", "A and B", "A and C", "B and C" or "A, B, and C".

[0035] It should also be understood that a network node (AMF 101 or SMF 102 in FIG. 1), which may also be referred to as a network function, may be implemented either as a network element on dedicated hardware, as a software instance running on dedicated hardware, or as a virtualized function instantiated on a suitable platform, for example, on a cloud infrastructure.

[0036] In one embodiment, the communication system 100 may be set up in an over-the-top (OTT) scenario. The OTT connection may be transparent in the sense that the involved communication devices through which the OTT connection passes are unaware of the routing of the uplink and downlink communications. For example, a base station may not be aware, or need not be aware of, the past routing of an incoming downlink communication involving data originating from a network function (such as the AMF 101 or SMF 102) in the core network that is forwarded (e.g., handed over) to a connected user equipment (UE). Similarly, the base station does not need to be aware of the future routing of an outgoing uplink communication originating from a UE to a network function (such as the AMF 101 or SMF 102) in the core network.

[0037] 1 is a schematic block diagram illustrating an example architecture 100 for a 5G network architecture in a non-roaming scenario. In a 5G core network, a service-based architecture describes several interaction patterns, such as a request / response pattern or a subscribe / notify pattern.

[0038] The subscribe / notify pattern assumes that a network function (NF) service consumer (such as the AMF 101) issues a request message (e.g., a "subscribe" operation) to an NF service producer (such as the SMF 102). Then, when a condition occurs at the NF service producer, the NF service producer issues a subsequent request (i.e., a "notify" operation) to the NF service consumer.

[0039] To ensure optimized data replication management, an NF producer or NF consumer may indicate the preferred scope of data replication in a "subscribe," "request," "notify," or "response" message by using binding indications.

[0040] A binding indication is information included in a response or notification to convey to an NF service consumer the extent to which selection / reselection of a target NF / NF service may be performed by an NF service producer, or information included in a request or subscription to convey to an NF service consumer the extent to which selection / reselection of a notification target or selection of other services that the NF consumer produces for the same data context may be performed.

[0041] Within the binding indication, the context owner (either the NF producer or the NF consumer) may specify a binding level to define the preferred scope of NF reselection. Exemplary binding levels for binding, selection, and reselection may be shown in Table 1 below. TIFF2025525558000002.tif144170

[0042] When a peer NF receives a binding indication, if it detects that the original NF is unavailable, it first selects a candidate within its preferred range (binding level). Only when all candidates within the binding level are unavailable, the peer NF may reselect a candidate outside the binding level.

[0043] The reason for the requirement in 3GPP TS29.500 may be due to protocol limitations. The binding indication may include a preferred binding entity corresponding to the binding level or another binding entity for reselection. When the binding level is an NF service instance, the NF service instance ID (as the preferred binding entity) must be included, but the NF service instance ID is not globally unique and must be provisioned with an NF instance ID or an NF service set ID, which leads to ambiguity as to whether this NF instance ID / NF service set ID is intended to identify an NF service instance or to describe a binding entity for reselection.

[0044] However, there are some use cases where an NF may want to indicate additional redundant information for selecting / reselecting an NF service instance or entity in addition to the existing binding indication, for example, an NF may want to indicate that a resource is bound exclusively to a specific NF service instance.

[0045] Use Case 1. Support of restoration procedures for home-routed PDU sessions or PDU sessions with I-SMF

[0046] When the Visited / Intermediate Session Management Function (V / I-SMF) does not support the PSETR feature as specified by 3GPP TS 29.502 (i.e., the V / I-SMF cannot reselect an alternative (home) SMF (i.e., the (H-)SMF) when it detects an (H-)SMF failure (unreachable)), while the H-SMF supports the DLSET feature as specified by 3GPP TS 29.502 (i.e., the (H-)SMF is deployed in an (H-)SMF SET), therefore, when the (H-)SMF fails, the PDU session is deleted by the V / I-SMF, but the PDU session resources are still kept in a shared memory, e.g., the UDSF, and the NF behind the (H)-SMF, e.g., the Policy Control Function / Unified Data Management (PCF / UDM) in the Home Public Land Mobile Network (HPLMN), is unaware that the PDU session cannot be restored (because it has been deleted in the Visited PLMN). Therefore, a means is needed to allow hanging resources to be deleted in the PCF / UDM (e.g., in the home PLMN). One solution could be that an alternative H-SMF in the same SMF set to which the failed SMF belongs somehow learns of the failure of the (H-)SMF, finds out that it cannot restore the PDU session (because the V / I-SMF deleted the PDU session), and then triggers the deletion. This alternative requires a complex mechanism using SMF sets to allow the SMFs in the set to be able to keep track of the state of each SMF in the set.

[0047] Use Case 2.NF is removed from the SMF set for the following scenarios: During a service software upgrade, i.e., being upgraded to a software version that makes newly created resources unable to be shared with other non-upgraded NF service instances in the set. The same applies to downgrades · Maintenance

[0048] for example, Assume there are five NFs in the set (1, 2, 3, 4, and 5) and NF1 is being upgraded. For any existing resource handled by NF1, Better to let other NFs in the same NF set do this, which can be done via notification requests by changing the preferred binding entity in the binding indication, on a per-resource basis or per group of resources if supported, or · Redirect any service requests received for existing resources that were created before they were removed from the set using 3xx.

[0049] For any new request, especially one that requires newly upgraded features, NF1 should accept the request since it is the first NF in the upgraded set, and there is no redundancy. This must be indicated to the NF service consumer.

[0050] If NF2 is then also upgraded, the binding instructions are further updated as NF1 and NF2 may form a new set, at which point existing resources (created before NF1's upgrade) will be handled by the new set.

[0051] Use Case 3. A set of NFs (services) is deployed using the UDSF as a centralized database to store resource information, so that any NF in the same (service) set may be able to retrieve the resource information and thus handle requests related to the resource.

[0052] However, if an NF temporarily loses connectivity to the UDSF, then any resources created or updated by this NF cannot be synchronized and stored in the UDSF, i.e., those newly created or updated resources cannot be provided by other NFs in the same set, i.e., they are exclusively bound to a specific NF service instance.

[0053] In view of the above deficiencies, embodiments herein propose a mechanism that allows an NF service instance to indicate that resources are bound exclusively to this NF service instance, and there is no redundancy in the associated resources.

[0054] FIG. 2 is a schematic block diagram illustrating an example architecture of a wireless communication system 200 that indicates additional redundancy information, for example, indicating no redundancy.

[0055] In one embodiment, the wireless communication system 200 may include, but is not limited to, a first NF 201 and a second NF 202. In one embodiment, the first NF 201 and the second NF 202 may be configured as any two of the NFs shown in FIG.

[0056] In one embodiment, the first NF 201 may be an NF service consumer, the second NF 202 may be an NF service producer, and the message may be a request message or a subscription message. As an example, the first NF 201 may be the AMF 101 in Figure 1, and the second NF 202 may be the SMF 102 in Figure 1.

[0057] In another embodiment, the first NF 201 may be an NF service producer, the second NF 202 may be an NF service consumer, and the message may be a response message or a notification message.

[0058] In one embodiment, the first NF 201 may be configured to send a message to the second NF 202. In one embodiment, the first NF 201 may include a binding indication in the message.

[0059] In addition to the binding indication, the first NF 201 may further include additional redundant information in the message. Such “additional redundant information” may be included in the binding indication or another HTTP header, or a new HTTP customer header.

[0060] As an example, the additional redundant information may include the following parameters in Table 2 below: TIFF2025525558000003.tif38170

[0061] In one embodiment, a timer may indicate the validity period of the redundancy level, ie, the additional redundancy information is valid until the timer expires.

[0062] In one embodiment, the redundancy level may be defined as a Boolean value. When the redundancy level is set to true, it may indicate no redundancy, i.e., the context may be bound exclusively to a specific NF service instance within the first network function.

[0063] In one embodiment, the redundancy level may be specified as an enumeration containing the values: "no-redundancy", "nfservinst", "nfservset", "nfinst". This indicates to the receiver the current redundancy level for the associated resource or session context, regardless of the binding level of the binding indication. When the redundancy level is set to "no-redundancy" or "nfservinst", it indicates that the resource is bound exclusively to this NF service instance.

[0064] As an example, the enumeration RedundancyLevel may include the following information in Table 3 below: In Table 3, the enumeration RedundancyLevel indicates the current redundancy level. TIFF2025525558000004.tif38170

[0065] The redundancy level may have a finer level than the binding entity indicated in the binding indication for reselection. For example, if the binding indication indicates that the binding level is an NF instance, the preferred binding entity is the NF instance, and the other binding entity (for reselection) is an NF set. Because the redundancy level can be set to an NF instance, it instructs the receiver to respect the additional redundancy information; that is, upon failure, the receiver can only select an alternative NF service instance within the NF instance rather than the NF set until the validity period expires. Once the timer expires, the receiver starts to directly use the binding indication as resilience information for the associated resource or session context.

[0066] The binding indication may further include a binding entity corresponding to the redundancy level. When the redundancy level is "NO_REDUNDANCY" or "NF_SERVICE_INSTANCE", the NF service instance ID is present in the binding indication, for example, nfservinst=xyz may be present. When the verbosity level is "NF_SERVICE_SET", the NF service set ID (e.g., nfservset=setxyz.snnsmf-pdusession.nfi54804518-4191-46b3-955c-ac631f953ed8.5gc.mnc012.mcc345) may be present in the binding indication. When the verbosity level is "NF_INSATNCE", the NF instance ID (e.g., nfinst=54804518-4191-46b3-955c-ac631f953ed8) may be present in the binding indication.

[0067] As seen above, there are some use cases where an NF wants to indicate that there is no redundancy for a resource, i.e., that the resource is bound exclusively to a unique NF service instance, even if the NF is or was part of an NF (service) set.

[0068] The embodiments aim to solve the problem / use case when an NF wants to indicate that a resource is exclusively bound to a specific NF service instance.

[0069] In one embodiment, a new data type "redundancy-info" is proposed, which includes "redundancy-level" as an enumeration including "no-redundancy". In particular, the embodiment allows an NF service instance to indicate that resources are bound exclusively to this NF service instance, and there is no redundancy for the associated resources using 3gpp-Sbi-Binding-Indication.

[0070] FIG. 3 is a schematic signaling chart illustrating messages in an exemplary procedure for indicating additional redundancy information (eg, indicating no redundancy) according to embodiments herein.

[0071] Figure 3 shows how an NF, whether an NF is an NF service consumer (e.g., AMF 101) or an NF service producer (e.g., SMF 102), can indicate to its peer NFs that resources or session contexts allocated to the NF producer or NF consumer are exclusively bound to a specific NF service instance. In the example, the binding indication may be used to convey additional redundant information. For simplicity, it is assumed that an NF instance (AMF 101 or SMF 102) contains only one NF service instance. For example, AMF1 has NF service instance abc, and SMF1 has NF instance xyz.

[0072] In one embodiment, a procedure for indicating additional redundancy information (eg, indicating no redundancy) may include the following messages or steps:

[0073] Step 1a. To establish a PDU session for UE1, AMF1 sends a request message to SMF1 to create an SmContext resource for the PDU session in SMF1. In the request message, AMF1 may include a 3gpp-Sbi-Binding for callback (i.e., a session context for the PDU session corresponding to the SmContext resource in SMF1).

[0074] For example, an example of a 3gpp-Sbi-Binding could be 3gpp-Sbi-Binding:bl=nf-instance;nfinst=54804518-4191-46b3-955c-ac631f953ed7(AMF1);nfset=set1.region48.amfset.5gc.mnc012.mcc345;scope=callback.

[0075] That is, the binding indication of the NF consumer may include the binding level of the NF instance and the identifier (AMF1) of the NF instance.

[0076] Step 1b. SMF1 may send a Create Response message that may include a Location header containing the Uniform Resource Identifier (URI) of the resource. The URI of the resource is used by AMF1 in subsequent signaling related to this resource. SMF1 may include 3gpp-Sbi-Binding:bl=nf-instance;nfinst=64804518-4191-46b3-955c-ac631f953ed8(SMF1);nfset=set1.smfset.5gc.mnc012.mcc345.

[0077] That is, the NF producer's binding instruction may indicate that for this resource, the binding level may be set to the NF instance level. Furthermore, the NF instance identifier (SMF1) may also be included in the NF producer's binding instruction.

[0078] Step 2a. To establish a PDU session for UE2, AMF1 may do the same as in step 1a and provide the same 3gpp-Sbi-Binding.

[0079] Step 2b. SMF1 may do the same as in step 1b and provide the same 3gpp-Sbi-Binding.

[0080] Step 3. SMF1 may leave the SMF set for several reasons, for example due to an upgrade, in which case the newly created resource context cannot be shared by other SMFs or other SMF service instances in the SMF set.

[0081] Step 4a. To establish a PDU session for UE3, AMF1 may do the same as in step 1a and provide the same 3gpp-Sbi-Binding.

[0082] Step 4b. SMF1 may send a Create Response message that may include a Location header containing the URI of the resource. The URI of the resource will be used by AMF1 in subsequent signaling related to this resource. SMF1 may include 3gpp-Sbi-Binding:bl=nfserviceinstance;nfservinst=xyz;nfinst=64804518-4191-46b3-955c-ac631f953ed8;no-redundancy=true.

[0083] That is, the NF producer's binding directive may indicate that for this resource, the binding level may be set to the NF service instance level. Furthermore, the NF service instance identifier (xyz) may also be included in the NF producer's binding directive.

[0084] In this example, the NF producer's binding indication may also include additional redundancy information (e.g., "no-redundancy=true") to indicate that there is no redundancy for this resource.

[0085] Here, in this example, the parameter "no-redundancy" is a Boolean value and can be set as "true" or "false". The parameter "no-redundancy" can be used to indicate whether the resource is bound exclusively to the NF service instance as identified in the binding indication. The "nfservset" or "nfinst" included in the binding indication is only used to identify the NF service instance, but is not used as a binding entity for reselection.

[0086] Step 5. AMF1 may leave the AMF set for some reasons, for example due to an upgrade. In this case, for the newly created resource context, the corresponding session context in the consumer cannot be shared by other AMFs in the AMF set.

[0087] Step 6a. To establish a PDU session for UE4, AMF1 may provide a binding indication, for example, 3gpp-Sbi-Binding:bl=nfserviceinstance;nfsercinst=abc;nfinst=54804518-4191-46b3-955c-ac631f953ed7;no-redundancy=true.

[0088] That is, the NF consumer binding instruction may indicate that for this resource, the binding level may be set to the NF service instance level. Furthermore, the NF service instance identifier (abc) may also be included in the NF consumer binding instruction.

[0089] In this example, the NF consumer's binding indication may also include additional redundancy information (e.g., "no-redundancy=true") to indicate that there is no redundancy for this resource.

[0090] Step 6b. SMF1 may send a create response message as it does in step 4b.

[0091] Embodiments of the present disclosure are further described, for example, by reference to the flowcharts of Figures 4 and 5. Figure 4 is a schematic flowchart illustrating an example method 400 in a first network function 201 (either an NF consumer or an NF producer), according to embodiments herein.

[0092] Method 400 may begin at step S401. In step S401, a first network function 201 may send a first message including a first parameter indicating no redundancy to indicate to a second network function 202 that a first context is bound exclusively to a unique NF service instance within the first network function 201. The unique NF service instance may be identified in a binding indication included in the first message.

[0093] In one embodiment, the message may further include a second parameter indicating a validation timer. The validation timer may indicate a validation period without redundancy.

[0094] In one embodiment, the validation timer may be included in the binding indication or in another HTTP header.

[0095] In one embodiment, the first network function 201 may be an NF service producer (such as the SMF 102), and the second network function 202 may be an NF service consumer (such as the AMF 101). Furthermore, the first context may be a resource context, and the first message may be a response message or a notification message.

[0096] In one embodiment, the first network function 201 may be an NF service consumer (such as the AMF 101), and the second network function 202 may be an NF service producer (such as the SMF 102). Furthermore, the first context may be a session context or a resource context, and the first message may be a request message or a subscription message.

[0097] In one embodiment, the first network function 201 may act as a home SMF for a home-routed PDU session, and each visited SMF for the home-routed PDU session does not support redundancy.

[0098] In one embodiment, the first network function 201 may be removed from the set of NFs by a service software upgrade, downgrade, or maintenance.

[0099] In one embodiment, the first network function 201 may temporarily lose connectivity to a UDSF shared by a set of NFs.

[0100] The method 400 may then proceed to step S402. In step S402, the first network function 201 may receive a second message from the second network function 202, the second message including a third parameter indicating no redundancy, to indicate that the second context is exclusively bound to a unique NF service instance within the second network function 202.

[0101] The method 400 may then proceed to step S403. In step S403, the first network function 201 may delete the second context if the second network function 202 is not available.

[0102] The above steps are only examples, and the first network function 201 may perform any of the actions described with respect to Figures 2-3 to enable the NF to input information related to redundancy (e.g., indicating no redundancy) and handling accordingly.

[0103] FIG. 5 is a schematic flowchart illustrating an exemplary method 500 in a second network function 202 (either an NF producer or an NF consumer), according to embodiments herein.

[0104] Method 500 may begin at step S501, in which the second network function 202 may receive a first message from the first network function 201, the first message including a first parameter indicating no redundancy, to indicate that a first context is bound exclusively to a unique NF service instance within the first network function 201. The unique NF service instance may be identified in a binding indication included in the first message.

[0105] In one embodiment, the message may further include a second parameter indicating a validation timer. The validation timer may indicate a validation period without redundancy.

[0106] In one embodiment, the validation timer may be included in the binding indication or in another HTTP header.

[0107] In one embodiment, the first network function 201 may be an NF service producer (such as the SMF 102), and the second network function 202 may be an NF service consumer (such as the AMF 101). Furthermore, the first context may be a resource context, and the first message may be a response message or a notification message.

[0108] In one embodiment, the first network function 201 may be an NF service consumer (such as the AMF 101), and the second network function 202 may be an NF service producer (such as the SMF 102). Furthermore, the first context may be a session context or a resource context, and the first message may be a request message or a subscription message.

[0109] In one embodiment, the first network function 201 may act as a home SMF for a home-routed PDU session, and each visited SMF for the home-routed PDU session does not support redundancy.

[0110] In one embodiment, the first network function 201 may be removed from the set of NFs by a service software upgrade, downgrade, or maintenance.

[0111] In one embodiment, the first network function 201 may temporarily lose connectivity to a UDSF shared by a set of NFs.

[0112] Method 500 may then proceed to step S502. In step S502, second network function 202 may delete the first context if first network function 201 is unavailable. Alternatively, second network function 202 may delete the first context if first network function 201 is unavailable when the validation timer indicates that no redundancy is within the validation period.

[0113] The above steps are merely examples, and the second network function 202 may perform any of the actions described with respect to Figures 2-3 to enable the NF to input information related to redundancy (e.g., indicating no redundancy) and handling accordingly.

[0114] FIG. 6 is a schematic block diagram illustrating an exemplary first network function 201, according to embodiments herein.

[0115] In one embodiment, the first network function 201 may include at least one processor 601 and a non-transitory computer-readable medium 602 coupled to the at least one processor 601. The non-transitory computer-readable medium 602 may store instructions executable by the at least one processor 601, such that the at least one processor 601 may be configured to perform steps in the exemplary method 400 shown in the schematic flowchart of Figure 4, details of which will be omitted herein.

[0116] It should be noted that the first network function 201 may be implemented as hardware, software, firmware, and any combination thereof. For example, the first network function 201 may include multiple units, circuits, modules, etc., each of which may be used to perform one or more steps of the example method 400 or one or more steps related to the first NF 201 (either the AMF 101 or the SMF 102).

[0117] It should be understood that the first network function 201 may be implemented either as a network element on dedicated hardware, as a software instance running on dedicated hardware, or as a virtualized function instantiated on a suitable platform, for example, on a cloud infrastructure.

[0118] FIG. 7 is a schematic block diagram illustrating an exemplary second network function 202, according to embodiments herein.

[0119] In one embodiment, the second network function 202 may include at least one processor 701 and a non-transitory computer-readable medium 702 coupled to the at least one processor 701. The non-transitory computer-readable medium 702 may store instructions executable by the at least one processor 701, such that the at least one processor 701 may be configured to perform steps in the exemplary method 500 shown in the schematic flowchart of Figure 5, details of which will be omitted herein.

[0120] It should be noted that the second network function 202 may be implemented as hardware, software, firmware, and any combination thereof. For example, the second network function 202 may include multiple units, circuits, modules, etc., each of which may be used to perform one or more steps of the example method 500 or one or more steps related to the second NF 202 (either the SMF 102 or the AMF 101).

[0121] It should be understood that the second network function 202 may be implemented either as a network element on dedicated hardware, as a software instance running on dedicated hardware, or as a virtualized function instantiated on a suitable platform, for example, on a cloud infrastructure.

[0122] 8 is a schematic block diagram illustrating an exemplary computer-implemented apparatus 800 according to embodiments herein. In one embodiment, the apparatus 800 may be configured as the above-mentioned apparatus, such as the AMF 101, the SMF 102, the first NF 201, or the second NF 202.

[0123] In one embodiment, the apparatus 800 may include at least one processor, such as, but not limited to, a central processing unit (CPU) 801, a computer-readable medium 802, and a memory 803. The memory 803 may comprise volatile memory (e.g., random access memory (RAM)) and / or non-volatile memory (e.g., a hard disk or flash memory). In one embodiment, the computer-readable medium 802 may be configured to store computer programs and / or instructions that, when executed by the processor 801, cause the processor 801 to perform any of the methods described above.

[0124] In one embodiment, computer-readable medium 802 (such as a non-transitory computer-readable medium) may be stored in memory 803. In another embodiment, the computer program may be stored at a remote location, e.g., in computer program product 804 (which may also be embodied as a computer-readable medium), and accessible by processor 801, e.g., via carrier 805.

[0125] The computer readable medium 802 and / or the computer program product 804 may be distributed and / or stored on a removable computer readable medium, such as a diskette, a CD (compact disc), a DVD (digital video disc), flash or similar removable memory medium (e.g., compact flash, SD (secure digital), memory stick, mini SD card, MMC multimedia card, smart media), HD-DVD (high definition DVD) or Blu-ray DVD, USB (universal serial bus) based removable memory medium, magnetic tape medium, optical storage medium, magneto-optical medium, bubble memory, or may be distributed as a propagated signal over a network (e.g., Ethernet, ATM, ISDN, PSTN, X.25, Internet, local area network (LAN), or similar network capable of transporting data packets to infrastructure nodes).

[0126] Furthermore, the following amendments are proposed to amend the current 3GPP technical specification 3GPP TS29.500 V17.7.0:

[0127] Title: Binding instructions for resources bound to a specific NF service instance Reason for change: As specified in TS29.500, the binding indication cannot be used to indicate that a resource is exclusively bound to a specific NF service instance. A binding indication shall not be used when a particular resource can only be provided by a specific NF service instance of an NF instance, i.e., when NF service instances of the same NF service cannot share resources within an NF instance. Resources for which no binding or routing binding indication is signaled shall be considered to be exclusively bound to one NF service instance, unless the NF service resource owner instance is part of an NF set (or AMF set) or an NF service set, or unless its NF profile in the NRF indicates that it supports NF service persistence within the NF instance (see clause 6.5 of 3GPP TS 23.527

[38] ).

[0128] The requirements highlighted in italics force the receiving NF (consumer or producer) to perform a service discovery procedure towards the NRF to determine if the resource is actually bound to a specific NF service instance, since the producer may not support binding indication.

[0129] Additionally, there are some use cases where an NF may want to indicate that a resource is bound exclusively to a specific NF service instance. 1. Support for restoration procedures for home-routed PDU sessions or PDU sessions with I-SMF When the H-SMF supports the DLSET feature (i.e., the (H-)SMF is deployed in the (H-)SMF SET), while the V / I-SMF does not support the PSETR feature (i.e., the V / I-SMF cannot reselect an alternative (H-)SMF when it detects an (H-)SMF failure (unreachable)), therefore, when the (H-)SMF fails, the PDU session is deleted by the V / I-SMF, but the PDU session resources are still held in a shared memory, e.g., the UDSF, and the NF behind the (H)-SMF, e.g., the PCF / UDM in the home PLMN, is unaware that the PDU session cannot be restored because it has been deleted in the visited PLMN. Therefore, a means is needed to enable hanging resources to be deleted in the PCF / UDM (e.g., in the HPLMN). One solution could be that an alternative H-SMF in the same SMF set as the failed SMF somehow learns about the failure of the (H-)SMF, finds out that it cannot restore the PDU session (because the V / I-SMF deleted it), and then triggers the deletion. This alternative requires a complex mechanism using SMF sets to enable the SMFs in the set to be able to keep track of the state of each SMF in the set.

[0130] 2. NF service instances are removed from the set for the following scenarios: During a service software upgrade, i.e., being upgraded to a software version that makes newly created resources unable to be shared with other non-upgraded NF service instances in the set. The same applies to downgrades · Maintenance

[0131] For example, suppose there are five NFs in the set (1, 2, 3, 4, and 5) and NF1 is being upgraded. For any existing resources handled by NF1, it may be better to move them to other NFs in the same NF set, which can be done via a notification request by changing the preferred binding entity in the binding indication, on a per-resource basis or per group of resources if supported, or by redirecting using a 3xx when a service request is received for an existing resource that was created before being moved from the set.

[0132] For any new request, especially one that requires newly upgraded features, NF1 should accept the request since it is the first NF in the upgraded set, and there is no redundancy. This must be indicated to the NF service consumer.

[0133] 3. Since an NF (service) set is deployed using the UDSF as a centralized database to store resource information, any NF in the same (service) set may be able to retrieve the resource information and therefore handle resource-related requests.

[0134] However, when an NF temporarily loses connectivity to the UDSF, in this situation, any resources created or updated by this NF cannot be synchronized and stored in the UDSF, i.e., those newly created or updated resources cannot be provided by other NFs in the same set, i.e., they are exclusively bound to a specific NF service instance.

[0135] Therefore, it is proposed to introduce a new parameter "no-redundancy" in 3gpp-Sbi-Binding as a Boolean value to indicate whether a resource / session context is exclusively bound to a specific NF service instance.

[0136] Summary of changes: In 3gpp-Sbi-Binding, a new parameter "no-redundancy" and associated description of the parameter are introduced as a Boolean value to indicate whether a resource / session context is exclusively bound to a specific NF service instance.

[0137] Consequences of non-approval: Some use cases where the NF wants to indicate that a resource is exclusively bound to a specific resource are not supported.

[0138] Proposed changes: ***First Change*** (Underlined text indicates what should be added to the 3GPP Technical Specification) 6.1.6.1 General This section specifies the application data model supported by the API.

[0139] 5.2.3.2.6 3gpp-Sbi-Binding This header contains a comma-separated list of binding directives from the HTTP server for storage and subsequent use by the HTTP client (see Section 6.12).

[0140] The header encoding follows the ABNF specified in IETF RFC7230

[12] . 3gpp-Sbi-Binding=“3gpp-Sbi-Binding” “:”1#(OWS“bl=”blvalue 1*(“;”OWS parameter)[“;”OWS recoverytime][“;”OWS notif-receiver][“;”OWS“group=”groupvalue][1*(“;”OWS groupparameter)]) blvalue=“nf-instance” / “nf-set” / “nfservice-instance” / “nfservice-set” parameter=parametername“=”token parametername=“nfinst” / “nfset” / “nfservinst” / “nfserviceset” / “servname” / “scope” / “backupamfinst” / “backupnf” recoverytime=“recoverytime=”OWS DQUOTE date-time DQUOTE notif-receiver=“nr=”URI;URI production rule from IETF RFC3986

[14] ,Appendix A groupvalue=“true” / “false” groupparameter=groupparametername“=”token groupparametername=“oldgroupid” / “groupid” / “uribase” / “oldnfinst / “oldservset” / “oldservinst” / “guami” no-redundancy="true" / "false"

[0141] The following parameters are specified: - scope: indicates the applicability of the binding indication to service requests other than notification requests, or in notification or callback responses. It can have one of the following values: - "other-service": The binding information applies to other services that the NF Service Consumer may later offer as an NF Service Producer (see Section 6.12.3). - "subscription-events": The binding information applies to subscription change event notifications (see Section 6.12.4). - "callback": The binding information applies to notification or callback requests (see Sections 6.12.4 and 6.12.5).

[0142] The absence of this parameter in a service request other than a notification request, or in a binding indication in a notification or callback response, shall be interpreted as "callback".

[0143] If the binding information applies to notification / callback requests and other services, two scope parameters may be present in the binding directive. servname: indicates the name of the service as specified in 3GPP TS29.510 [8] or indicates the name of a custom service, i.e. - for subscriptions or callbacks, i.e., when the scope parameter is absent or set to "callback" in the binding directive, the name of the service that handles the notification or callback request, or - The name of the other service to which the binding applies when present in a service request for another service that the NF service consumer may later offer as an NF service producer, i.e. in a binding indication with the scope parameter set to "other-service". More than one servname parameter may be present to represent multiple such services. The absence of this parameter in a binding indication with the scope parameter set to "other-service" shall be interpreted as binding information that applies to all services that the NF service consumer may later offer as an NF service producer. - recoverytime: indicates the recovery timestamp of the entity corresponding to the highest resiliency level supported for the resource, i.e., the highest level binding entity indicated in the binding indication. See Table 6.3.1.0-1 of 3GPP TS23.501 [3] and Clause 6.1 of 3GPP TS23.527

[38] . The date-time type is specified in IETF RFC5322

[37] and IETF RFC7231

[11] , Clause 7.1.1.1. - nr: Indicates the URI of the notification endpoint when this binding information is applicable. It applies to callback requests (see Section 6.12.4). If the notification URI does not contain a correlationID in its path (i.e., it is a common notification URI for multiple subscriptions), the correlationID shall be appended to the end of the URI as the fragment component of the URI (i.e., following the "#" character). - See Section 5.2.3.2.5 for the conventions and encodings of blvalue, nfinst, backupamfinst, nfset, nfservinst, and nfserviceset. - backupnf: indicates the backup NF service instance identifier and / or backup NF identifier as specified in clause 5.2.2.2.2 or 3GPP TS29.510 [8], which shall be used when the preferred binding entity is not reachable if supported. - group: A Boolean value indicating whether the binding indication is for a group of resource / session contexts. - groupid indicates the group identifier assigned by the NF (service) instance, where one or more resource / session contexts share the same groupid. The groupid is optional and can be assigned when a resource / session context is created and then subsequently updated. The groupid is globally unique and can be encoded using the same mechanism as the NfInstanceId, as specified in 3GPP TS29.571

[13] . - oldgroupid (old group ID): indicates the group identifier previously assigned by the NF (service) instance and to be replaced by groupid, and is therefore only present when the binding indication for multiple contexts is to be updated. When oldgroupid is present, groupid shall also be present to indicate the new groupid assigned. - uribase: Identifies the apiroot and path segment portion of a resource URI or notification / callback URI that is common to multiple contexts. This parameter may only be present when binding directives for multiple contexts are to be updated and when "group" is set to "true". When included, it indicates that all resource or notification contexts with this uribase will subsequently use the updated binding directives. More than one uribase may be present. - oldnfinst: indicates the NF instance ID of the NF instance on which the resource / session context group is currently provided (i.e., the binding indication previously assigned to the resource / session context group contains the NF instance information), as specified in clause 5.2.2.2.2 of 3GPP TS29.510 [8]. When included, indicates that all resource / session contexts provided by this NF instance will subsequently use the updated binding indication. - oldservset: indicates the NF Service Set ID of the NF Service Set for which a group of resources / session contexts is currently provided (i.e., the binding indication previously assigned to the group of resources / session contexts contains the NF Service Set information), as specified in clause 5.2.2.2.2 of 3GPP TS29.510 [8]. When included, indicates that all resources / session contexts provided by this NF Service Set will subsequently use the updated binding indication. - oldservinst: indicates the NF service instance ID of the NF service instance for which a group of resources / session contexts is currently being provided (i.e. the binding indication previously assigned to the group of resources / session contexts contains the NF service instance information), as specified in clause 5.2.2.2.2 of 3GPP TS29.510 [8]. When included, indicates that all resources / session contexts provided by this NF service instance will subsequently use the updated binding indication. - GUAMI: Indicates the GUAMI of the AMF currently providing the UE context, as specified in clause 5.3.4.1 of 3GPP TS 29.571

[13] . When included, indicates that all UE contexts associated with the GUAMI will subsequently use the updated binding indication. - no-redundancy: A Boolean value indicating whether the resource is bound exclusively to the NF service instance as identified in the binding indication. When this is set to true, the nfservset or nfinst contained in the binding indication shall only be used to identify the NF service instance and shall not be considered as a binding entity for reselection purposes.

[0144] Examples 1 to 5: The same as Examples 1 to 5 specified in clause 5.2.3.2.5, with the header name "3gpp-Sbi-Binding" instead of "3gpp-Sbi-Routing-Binding".

[0145] Example 6: Subscription request from one NF on behalf of another NF with two binding indications: 3gpp-Sbi-Binding:bl=nf-set;nfset=set1.udmset.5gc.mnc012.mcc345;servname=nudm-ee;scope=subscription-events 3gpp-Sbi-Binding:bl=nf-set;nfset=set1.nefset.5gc.mnc012.mcc345;servname=nnef-event-exposure

[0146] Example 7: A service request with two binding indications, one for a callback request and one for another service that the NF service consumer may later provide as an NF service producer: 3gpp-Sbi-Binding:bl=nf-instance;nfinst=54804518-4191-46b3-955c-ac631f953ed8;nfset=set1.smfset.5gc.mnc012.mcc345;servname=nsmf-pdusession 3gpp-Sbi-Binding:bl=nf-instance;nfinst=54804518-4191-46b3-955c-ac631f953ed8;nfset=set1.smfset.5gc.mnc012.mcc345;scope=other-service;servname=nsmf-event-exposure

[0147] Example 8: Service request with one binding indication that applies to the notification / callback request and any other services that the NF service consumer may later provide as an NF service producer: 3gpp-Sbi-Binding:bl=nf-set;nfset=set1.region48.amfset.5gc.mnc012.mcc345;scope=callback;scope=other-service

[0148] Example 9: Service request with one binding directive applied to a notification / callback request with the recovery timestamp associated with the NF set indicated in the binding directive and the binding level set to "nfset": 3gpp-Sbi-Binding:bl=nfset;nfset=set1.region48.amfset.5gc.mnc012.mcc345;scope=callback;recoverytime=“Tue,04 Feb 2020 08:49:37 GMT”

[0149] Example 10: Service response with one binding indication that applies to a session context, with recovery timestamps associated with the NF set indicated by "nfset" in the binding indication and binding level set to "nfinstance": 3gpp-Sbi-Binding:bl=nfinstance;nfinst=54804518-4191-46b3-955c-ac631f953ed8;nfset=set1.smfset.5gc.mnc012.mcc345;recoverytime=“Tue,04 Feb 2020 08:49:37 GMT”

[0150] Example 11: Service response with one binding indication applied to a session context, with a recovery timestamp associated with the NF instance included in the binding indication and binding level set to nfserviceinstance: 3gpp-Sbi-Binding:bl=nfserviceinstance;nfservinst=xyz;nfinst=54804518-4191-46b3-955c-ac631f953ed8;recoverytime=“Tue,04 Feb 2020 08:49:37 GMT”

[0151] Example 12: Service response with one binding directive applied to a resource context for the group identified by "54804518-4191-46b3-955c-ac631f953ed1" with backup nf: 3gpp-Sbi-Binding:bl=nfinstance;nfinst=54804518-4191-46b3-955c-ac631f953ed0;nfset=set1.smfset.5gc.mnc 012.mcc345;groupid=54804518-4191-46b3-955c-ac631f953ed1;backupnf=54804519-4191-46b3-955c-ac631f953ed2

[0152] Example 13: A notification request message with one binding indication applied to a resource context with oldgroup identifier "54804518-4191-46b3-955c-ac631f953ed1", where the preferred binding entity is changed to "nfinst=54804519-4191-46b3-955c-ac631f953ed0" with an assigned new group identifier "54804519-4191-46b3-955c-ac631f953ed3". 3gpp-Sbi-Binding:bl=nfinstance;nfinst=54804519-4191-46b3-955c-ac631f953ed0;nfset=set1.smfset.5gc.mnc012.mcc 345;group=true;oldgroupid=54804518-4191-46b3-955c-ac631f953ed1;groupid=54804519-4191-46b3-955c-ac631f953ed3

[0153] Example 14: A notify request message with one binding indication that applies to a resource context identified by uribase, where the preferred binding entity is changed to "nfinst=54804519-4191-46b3-955c-ac631f953ed0". 3gpp-Sbi-Binding:bl=nfinstance;nfinst=54804519-4191-46b3-955c-ac631f953ed0;nfset=se t1.smfset.5gc.mnc012.mcc345;group=true;uribase=http%3A%2F%2F10.10.10.10%2Fstringxyz

[0154] Example 15: A notification request message with one binding indication that applies to a resource context provided by an NF instance identified by "64804518-4191-46b3-955c-ac631f953ed8", where the preferred binding entity is changed to "nfinst=74804519-4191-46b3-955c-ac631f953ed0". 3gpp-Sbi-Binding:bl=nfinstance;nfinst=74804519-4191-46b3-955c-ac631f953ed0;nfset=set 1.smfset.5gc.mnc012.mcc345;group=true;oldnfinst=64804518-4191-46b3-955c-ac631f953ed8

[0155] Example 16: GUAMI<mnc(012)><mcc(345)><AmfId(“abcd12”)> " is a service request message with updated binding indications to be applied to the UE context in "backupamfinst" and backupamfinst is changed. 3gpp-Sbi-Binding:bl=nf-instance;nfinst=54804518-4191-46b3-955c-ac631f953ed7;backupamfinst=54804520-4191-46b3 -955c-ac631f953ed8;scope=other-service;group=true;guami={“plmnId”:{“mnc”:“012”,“mcc”:“345”},“amfId”:“abcd12”}

[0156] Example X: A service response with binding instructions that apply to a resource context bound exclusively to a specific NF instance. 3gpp-Sbi-Binding:bl=nfserviceinstance;nfservinst=xyz;nfinst=54804518-4191-46b3-955c-ac631f953ed8;no-redundancy=true

[0157] Note: Examples 6 and 7 are formatted as two separate headers (which improves readability), but they could also be formatted as a single header with the values of the two binding directives separated by a comma.

[0158] ***Second Change*** (Underlined text indicates content to be added to the 3GPP Technical Specification) 6.12.1 Overview A binding indication for an NF service resource can be provided to an NF service consumer of the resource as part of a direct or indirect communication procedure, to be used in subsequent related service requests. This allows an NF service resource owner to indicate that for a particular resource, an NF service consumer should be bound to an NF service instance, an NF instance, an NF service set, or an NF set. See clause 6.3.1.0 of 3GPP TS23.501[3] and clause 4.17.12 of 3GPP TS23.502[4].

[0159] Bindings can be established or updated as part of: 1) For any API that specifies a resource, a service response that creates or modifies a resource to be used for subsequent requests that target this resource (see clause 4.17.12.2 of 3GPP TS23.502 [4]). 2) A service request to be used for subsequent service requests initiated by the contacted NF service producer, in case the NF service consumer is able to act as the NF service producer for subsequent communications from the contacted NF service producer (see clause 4.17.12.3 of 3GPP TS 23.502 [4]). 3) Service requests (see clause 4.17.12.3 of 3GPP TS23.502 [4]) to create or modify explicit or implicit subscriptions to be used for subsequent notification requests initiated by the NF service producer, or as part of a notification response. 4) A service response (see clause 4.17.12.4 of 3GPP TS 23.502 [4]) to create an implicit or explicit subscription, or to renew a subscription, or as part of a notification request, to be used for subsequent operations on the subscription. 5) Creating callback resources (other than notifications) (e.g., V-SMF or I-SMF callback URIs sent to the H-SMF or SMF) to be used for subsequent callback requests initiated by the NF service producer (e.g., H-SMF or SMF initiated PDU session modifications), or as part of a callback response, a service request 6) A callback request sent by the NF service producer to update the binding of the resource context to be used by the NF service consumer for subsequent service requests destined for the resource context.

[0160] Two types of binding information are specified to manage the binding between NF service consumers and NF service resources. 1) A binding indication conveys binding information about a resource that must be stored by a consumer (client) of that resource and used by the client to direct future requests to the resource. When included in a service request, the binding information is associated with a resource owned by the NF service consumer for the current transaction. When included in a service response, the binding information is associated with a resource owned by the NF service producer for the current transaction. 2) The routing binding directive conveys binding information to direct requests from a client to a server that has the context. The routing binding directive shall only be included in HTTP requests.

[0161] The same service request may carry more than one binding indication, for example: - To provide bindings for notifications or callbacks (i.e., bullets 3 or 5) and other services that the NF service consumer may later offer as an NF service producer (i.e., bullet 2), or - To provide binding information for different event notifications when creating a subscription on behalf of another NF (see Section 6.12.4)

[0162] The scope parameter of the binding indication in the service request (or notification or callback response) identifies the applicability of the binding information (i.e., the scenario associated with the binding information).

[0163] A service request may carry one or more binding indications as described above using the 3gpp-Sbi-Binding header and / or may include binding routing indications, e.g., to influence the routing of the request to an appropriate set of NF service producers or an appropriate set of services of an NF service producer using the 3gpp-Sbi-Routing-Binding header. A service response may carry binding indications for resources using the 3gpp-Sbi-Binding header.

[0164] Note 1: The HTTP request may include, for example, one 3gpp-Sbi-Binding header containing two binding indications for other services and callbacks, and one 3gpp-Sbi-Routing-Binding header carrying the routing binding indication.

[0165] Once a binding indication has been received for a particular resource or range, unless otherwise specified in the remainder of this specification, the absence of a binding indication for the same resource or range in a subsequent request / response message shall be interpreted as meaning that the previously received binding indication for that resource or range has not changed (see further below in Section 6.12.4 for scenarios with NF service producer or consumer changes and inter-AMF mobility scenarios).

[0166] In a scenario with a change of NF service producer (e.g., change of V-SMF or I-SMF), the NF service consumer (e.g., AMF) removes any previous binding indications received from the old NF service producer (e.g., old V-SMF / I-SMF) for the producer's resources (e.g., SM context resources) and replaces them with any new binding indications that may have been received from the new NF service producer (e.g., new V-SMF / I-SMF).

[0167] In a scenario with a change of NF service consumer (e.g., inter-AMF mobility), the NF service producer (e.g., SMF) removes any previous binding indications received from the old NF service consumer (e.g., binding indications for callback requests received from the old AMF) and replaces them with any new binding indications that may have been received from the new NF service consumer (e.g., new AMF).

[0168] When an SCP receives a routing binding indication in a service or notification request and decides to forward the request to an adjacent hop SCP, the SCP includes the routing binding indication in the forwarded request. The SCP removes the routing binding indication when forwarding the request to the target NF.

[0169] The binding indication and the routing binding indication include a binding level and one or more binding entity IDs that represent all NF service instances that allow serving service requests targeting a resource, i.e., that share the same resource context.

[0170] The binding level indicates the preferred binding for either an NF instance, an NF set, an NF service instance, or an NF service set.

[0171] When sending a request targeting a resource context at an NF service producer or a session context at an NF service consumer, the resource URI or notification / callback URI received in the Location header is first used to set the "3gpp-Sbi-Target-apiRoot" header or target URI, if available. As an exception, if a previously received binding indication for the target resource context or session context indicates a binding level of "NF Service Set", "NF Instance", or "NF Set", and if alternative NF service instances in the preferred binding entity corresponding to the binding level are available, the request may alternatively be sent to one of these alternative NF service instances. When the URI or notification / callback URI received in the Location header is unreachable, or upon recognition of a change in the NF service producer or consumer as specified in bullet point 3 of clauses 6.5.3.2 and 6.5.3.3, the binding entity corresponding to the binding level shall be selected whenever possible. If this is not possible, for example because the preferred binding entity is not reachable, the request should be sent to any other binding entities signaled in the binding indication or routing binding indication, in the following descending order of priority: - if a backup NF service instance and / or a backup NF instance is signaled in the binding indication or routing binding indication, select the NF service instance of the backup NF instance, if available; - If an NF Service Set ID is signaled in the binding or routing binding indication, select an NF service instance within the same NF Service Set. - If an NF instance ID is signaled in the binding or routing binding indication, select an equivalent NF service instance within the same NF instance. - If the NF service set ID and backup AMF instance ID are signaled in the binding indication or routing binding indication, select the NF service instance in the equivalent NF service set of the backup AMF instance. - If a backup AMF instance ID is signaled in the binding indication or routing binding indication, select the equivalent NF service instance in the backup AMF instance. - If an NF Service Set ID and an NF Set ID are signaled in a binding or routing binding indication, select an NF service instance within an equivalent NF Service Set of another NF instance of the NF Set. - If an NF Set ID is signaled in the binding or routing binding indication, select an equivalent NF service instance in another NF instance of the NF Set.

[0172] NOTE 2: NF service instances from different NF instances are equivalent NF service instances if they share the same MCC, MNC, NID (for SNPN), service name, API version, and, if applicable, NF service set ID (see clause 28.13 of 3GPP TS 23.003

[15] ).

[0173] Unless the receiver of the binding indication indicates that it supports the no-redundancy indication in the binding indication in the SupportFeatures attribute for the specific API,Binding indications shall not be used when a particular resource can only be provided by a ,specific NF service instance of an NF instance, i.e., when NF service instances of the same NF service ,cannot share resources within an NF instance., ,Resources for which no binding or routing binding indication is signaled shall be considered ,to be exclusively bound to one NF service instance, unless the NF service resource owner instance is ,part of an NF set (or AMF set) or an NF service set, or unless its NF profile in the NRF ,indicates that it supports NF service persistence within an NF instance (see ,clause 6.5 of 3GPP TS 23.527

[38] ).

[0174] NF service producers that support different sets of NF service instances, e.g., providing different network slices, include the NF service set ID in the binding indication to enable reselection (if necessary) of an alternative NF service instance from the same or equivalent NF service set. See also clause 6.10.3.2 for requirements regarding the inclusion of "3gpp-Sbi-Discovery-*" headers in service requests targeting existing resource contexts at the NF service producer.

[0175] A binding indication can be shared by multiple resource / session contexts, i.e., these resource contexts (at the NF service producer) or session contexts (at the NF service consumer) share the same resilience information. Binding indications for multiple contexts have the same semantics as for a single resource / session context, with the following additions: When supported as indicated in the supported features for a specific service API, - NF service consumers and NF service producers MAY indicate whether a binding indication is for multiple contexts, and if the binding indication is for multiple contexts, the "group" parameter in the binding indication shall be set to "true". - A group ID may be included in the binding indication when a resource / session context is created to indicate that the group to which the resource / session context belongs shares the same binding indication. - A binding indication for a group of contexts can be updated when an NF service consumer provides a callback URI, e.g., when an NF is changed, each resource URI with a different apiRoot part (representing a different peer NF (service) instance), or each notification URI with a different authority part, or the same authority part but with a different callback-uri-prefix (see Section 5.2.3.3.7), is provided in the 3gpp-Sbi-Consumer-Info header, by including oldgroupid, oldnfinst, oldservset, oldservinst, or uribase to address the applicable context for the binding indication update. When oldgroupid is present, groupid is also present to indicate the newly assigned new group ID. Furthermore, a binding indication can be updated for a group of UE contexts by including gumai to address the applicable UE context for the binding indication update. ***END OF CHANGE***

[0176] Exemplary embodiments have been described herein with reference to block diagrams and / or flowchart illustrations of computer-implemented methods, apparatus (systems and / or devices), and / or non-transitory computer program products. It should be understood that blocks of the block diagrams and / or flowchart illustrations, and combinations of blocks in the block diagrams and / or flowchart illustrations, may be implemented by computer program instructions performed by one or more computer circuits. These computer program instructions may be provided to processor circuits of general-purpose computer circuits, special-purpose computer circuits, and / or other programmable data processing circuits to create machines, such that the instructions executing via the processor of the computer and / or other programmable data processing apparatus transform and control transistors, values stored in memory locations, and other hardware components within such circuits to implement the functions / acts specified in one or more blocks of the block diagrams and / or flowcharts, and thereby create means (functions) and / or structures for implementing the function / acts specified in the block diagram and / or flowchart block(s).

[0177] These computer program instructions may also be stored on a tangible computer-readable medium that may direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored on the computer-readable medium produce an article of manufacture containing instructions that implement the functions / acts specified in one or more blocks of the block diagrams and / or flowcharts. Thus, embodiments of the inventive concepts may be embodied in hardware and / or in software (including firmware, resident software, microcode, etc.) running on a processor, such as a digital signal processor, which may be collectively referred to as a "circuit," "module," or variations thereof.

[0178] It should also be noted that in some alternative implementations, the functions / acts noted in the blocks may occur out of the order noted in the flowcharts. For example, two blocks shown in succession may in fact be executed substantially concurrently, or the blocks may sometimes be executed in reverse order, depending on the functions / acts involved. Moreover, the functionality of a given block of the flowcharts and / or block diagrams may be separated into multiple blocks, and / or the functionality of two or more blocks of the flowcharts and / or block diagrams may be at least partially integrated. Finally, other blocks may be added / inserted between the shown blocks, and / or blocks / acts may be omitted without departing from the scope of the inventive concept. Moreover, while some of the figures include arrows on communication paths to indicate a primary direction of communication, it should be understood that communication may occur in the opposite direction to the illustrated arrows.

[0179] Many variations and modifications may be made to the embodiments without substantially departing from the principles of the inventive concept. All such variations and modifications are intended to be included herein within the scope of the inventive concept. Accordingly, the inventive subject matter disclosed above should be considered exemplary, and the accompanying example embodiments are intended to cover all such modifications, enhancements, and other embodiments that fall within the spirit and scope of the inventive concept. Accordingly, to the maximum extent permitted by law, the scope of the inventive concept should be determined by the broadest permissible interpretation of this disclosure, including the following example embodiments and their equivalents, and is not intended to be constrained or limited to the detailed description set forth above.

[0180] Abbreviation 3GPP 3rd Generation Partnership Project 5G The fifth generation of mobile communications technology AMF Access and Mobility Management Functions HTTP Hypertext Transfer Protocol NF Network Function OTT Over-the-top PCF Policy Control Function PDU Packet Data Unit PLMN Public Land Mobile Network SMF Session Management Facility UDM Unified Data Management UDSF Unstructured Data Storage Facility UE User Equipment URI Uniform Resource Identifier

Claims

1. A method (400) performed by a first network function (201), comprising: sending a first message including a first parameter indicating no redundancy to a second network function (202) to indicate that a first context is exclusively bound to a unique network function (NF) service instance within said first network function (201); The method (400), wherein the unique NF service instance is identified in a binding indication included in the first message.

2. 2. The method (400) of claim 1, wherein the first message further comprises a second parameter indicating a validation timer, the validation timer indicating a validation period without the redundancy.

3. 3. The method (400) of claim 2, wherein the validation timer is included in the binding indication or another HyperText Transfer Protocol (HTTP) header.

4. The first network function (201) is an NF service producer (102), and the second network function (202) is an NF service consumer (101), the first context is a resource context; The method (400) of any one of claims 1 to 3, wherein the first message is a response message or a notification message.

5. The first network function (201) is an NF service consumer (101), and the second network function (202) is an NF service producer (102), the first context is a session context or a resource context; The method (400) of any one of claims 1 to 3, wherein the first message is a request message or a subscription message.

6. the first network function (201) acts as a home session management function (SMF) for home-routed packet data unit (PDU) sessions, and each visited SMF for the home-routed PDU sessions does not support redundancy; The first network function (201) is removed from the set of NFs due to a service software upgrade, downgrade or maintenance, or The method (400) of any one of claims 1 to 5, wherein the first network function (201) temporarily loses connectivity to an Unstructured Data Storage Function (UDSF) shared by a set of NFs.

7. receiving (S402) from the second network function (202) a second message including a third parameter indicating no redundancy to indicate that a second context is exclusively bound to a unique NF service instance within the second network function (202); - deleting (S403) said second context if said second network function (202) is unavailable; The method (400) of any one of claims 1 to 6, further comprising:

8. A method (500) performed by a second network function (202), comprising: receiving (S501) from a first network function (201) a first message including a first parameter indicating no redundancy to indicate that a first context is exclusively bound to a unique network function (NF) service instance within said first network function (201); The method (500), wherein the unique NF service instance is identified in a binding indication included in the first message.

9. 9. The method (500) of claim 8, wherein the first message further comprises a second parameter indicating a validation timer, the validation timer indicating a validation period without redundancy.

10. The method (500) according to claim 8 or 9, further comprising: deleting (S502) said first context if said first network function (201) is unavailable.

11. The method (500) of claim 9, further comprising: deleting (S502) the first context if the first network function (201) is not available when the validation timer indicates that the no-redundancy is within the validation period.

12. 12. The method (500) of claim 9 or 11, wherein the validation timer is included in the binding indication or another HyperText Transfer Protocol (HTTP) header.

13. The first network function (201) is an NF service producer (102), and the second network function (202) is an NF service consumer (101), the first context is a resource context; The method (500) of any one of claims 8 to 12, wherein the first message is a response message or a notification message.

14. The first network function (201) is an NF service consumer (101), and the second network function (202) is an NF service producer (102), the first context is a session context or a resource context; The method (500) of any one of claims 8 to 12, wherein the first message is a request message or a subscription message.

15. the first network function (201) acts as a home session management function (SMF) for home-routed packet data unit (PDU) sessions, and each visited SMF for the home-routed PDU sessions does not support redundancy; The first network function (201) is removed from the set of NFs due to a service software upgrade, downgrade or maintenance, or 15. The method (500) of any one of claims 8 to 14, wherein the first network function (201) temporarily loses connectivity to an Unstructured Data Storage Function (UDSF) shared by a set of NFs.

16. A first network function (201), At least one processor (601); a non-transitory computer-readable medium (602) coupled to the at least one processor (601); and wherein the non-transitory computer-readable medium (602) includes instructions executable by the at least one processor (601), whereby the at least one processor (601) is configured to perform the method (400) of any one of claims 1 to 7.

17. a second network function (202), At least one processor (701); a non-transitory computer-readable medium (702) coupled to the at least one processor (701); and wherein the non-transitory computer-readable medium (702) includes instructions executable by the at least one processor (701), whereby the at least one processor (701) is configured to perform the method (500) of any one of claims 8 to 15.

18. A computer-readable medium (602, 702, 802) comprising computer-readable code that, when run on a device (101, 102, 201, 202, 800), causes the device (101, 102, 201, 202, 800) to perform a method (400, 500) according to any one of claims 1 to 15.

19. A computer program product (804) comprising computer readable code that, when run on a device (101, 102, 201, 202, 800), causes the device (101, 102, 201, 202, 800) to perform the method (500) of any one of claims 1 to 15.

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