WO2021140051A1

WO2021140051A1 - Queries in a network

Info

Publication number: WO2021140051A1
Application number: PCT/EP2020/088011
Authority: WO
Inventors: Nagendra Shridhar BYKAMPADI; Jani Ekman; Silke Holtmanns
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2020-01-09
Filing date: 2020-12-30
Publication date: 2021-07-15
Anticipated expiration: 2022-07-09

Abstract

According to an example aspect of the present invention, there is provided an apparatus comprising a memory configured to store an identifier or address of a network support function assigned to a public land mobile network, and at least one processing core configured to cause transmission, from the apparatus to the network support function assigned to the public land mobile network, of a request message and to process a response message from the network support function assigned to the public land mobile network, the response message comprising information on one or more network support functions of a same type as the network support function assigned to the public land mobile network.

Description

QUERIES IN A NETWORK

FIELD

[0001] The present disclosure relates to communication between network functions and network support functions.

BACKGROUND

[0002] In networks supporting wireless or wire-based communication, discovering network functions, NF, and network function services is of interest. Core network, CN, entities may seek to discover a set of one or more NF instances and NF service instances for a specific NF service or an NF type. Examples of such CN entities include NFs and service communication proxies, SCP. Examples of NF instances to be discovered include application functions, gateways and subscriber repositories. Further examples include a (radio) access or resource control or management function, session management or control function, interworking, data management or storage function, authentication function or a combination of one or more of these functions. NF service instances, known also as NF services, include individual services provided by an NF. One NF may be configured to provide more than one service, wherein each of the more than one service may be reachable using a different approach, such as a different port or communication protocol.

[0003] NF service discovery may be enabled via a NF discovery procedure, as specified for wireless communication networks in technical specifications established by the third generation partnership project, 3GPP, for example. However, technology disclosed herein has relevance also to wire-line communication networks, such as internet protocol, IP, based networking.

SUMMARY

[0004] According to some aspects, there is provided the subject-matter of the independent claims. Some embodiments are defined in the dependent claims. The scope of protection sought for various embodiments of the invention is set out by the independent claims. The embodiments, examples and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention.

[0005] According to a first aspect of the present disclosure, there is provided an apparatus comprising a memory configured to store an identifier or address of a network support function assigned to a public land mobile network, and at least one processing core configured to cause transmission, from the apparatus to the network support function assigned to the public land mobile network, of a request message and to process a response message from the network support function assigned to the public land mobile network, the response message comprising information on one or more network support functions of a same type as the network support function assigned to the public land mobile network.

[0006] According to a second aspect of the present disclosure, there is provided an apparatus comprising a memory configured to store information concerning plural network support functions of a same type as a network support function run in the apparatus, and at least one processing core configured to receive, from a network function or a service communication proxy, a request message and to cause transmission, from the apparatus, of a response message, the response message comprising information on one or more network support functions of the same type as the network support function run in the apparatus.

[0007] According to a third aspect of the present disclosure, there is provided a method comprising storing an identifier or address of a network support function assigned to a public land mobile network, transmitting, from an apparatus to the network support function assigned to the public land mobile network, a request message, and processing a response message from the network support function assigned to the public land mobile network, the response message comprising information on one or more network support functions of a same type as the network support function assigned to the public land mobile network.

[0008] According to a fourth aspect of the present disclosure, there is provided a method comprising storing information concerning plural network support functions of a same type as a network support function run in an apparatus performing the method, receiving, from a network function or a service communication proxy, a request message, and transmitting from the apparatus a response message, the response message comprising information on one or more network support functions of the same type as the network support function run in the apparatus. [0009] According to a fifth aspect of the present disclosure, there is provided an apparatus comprising means for storing an identifier or address of a network support function assigned to a public land mobile network, transmitting, from an apparatus to the network support function assigned to the public land mobile network, a request message, and processing a response message from the network support function assigned to the public land mobile network, the response message comprising information on one or more network support functions of a same type as the network support function assigned to the public land mobile network.

[0010] According to a sixth aspect of the present disclosure, there is provided an apparatus comprising means for storing information concerning plural network support functions of a same type as a network support function run in an apparatus performing the method, receiving, from a network function or a service communication proxy, a request message, and transmitting from the apparatus a response message, the response message comprising information on one or more network support functions of the same type as the network support function run in the apparatus.

[0011] According to a seventh aspect of the present disclosure, there is provided a non- transitory computer readable medium having stored thereon a set of computer readable instructions that, when executed by at least one processor, cause an apparatus to at least store an identifier or address of a network support function assigned to a public land mobile network, transmit, from the apparatus to the network support function assigned to the public land mobile network, a request message, and process a response message from the network support function assigned to the public land mobile network, the response message comprising information on one or more network support functions of a same type as the network support function assigned to the public land mobile network.

[0012] According to an eighth aspect of the present disclosure, there is provided a non- transitory computer readable medium having stored thereon a set of computer readable instructions that, when executed by at least one processor, cause an apparatus to at least store information concerning plural network support functions of a same type as a network support function run in the apparatus, receive, from a network function or a service communication proxy, a request message, and transmit from the apparatus a response message, the response message comprising information on one or more network support functions of the same type as the network support function run in the apparatus. [0013] According to an ninth aspect of the present disclosure, there is provided a computer program configured to cause, when executed, an apparatus to perform at least the following: storing an identifier or address of a network support function assigned to a public land mobile network, transmitting, from the apparatus to the network support function assigned to the public land mobile network, a request message, and processing a response message from the network support function assigned to the public land mobile network, the response message comprising information on one or more network support functions of a same type as the network support function assigned to the public land mobile network.

[0014] According to a tenth aspect of the present disclosure, there is provided a computer program configured to cause, when executed, an apparatus to perform at least the following: storing information concerning plural network support functions of a same type as a network support function run in the apparatus, receiving, from a network function or a service communication proxy, a request message, and transmitting from the apparatus a response message, the response message comprising information on one or more network support functions of the same type as the network support function run in the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIGURE 1 illustrates an example system in accordance with at least some embodiments of the present invention;

[0016] FIGURES 2A - 2E illustrate architectural options relevant to at least some embodiments of the present invention;

[0017] FIGURE 3 illustrates an example apparatus capable of supporting at least some embodiments of the present invention;

[0018] FIGURE 4A - 4B illustrate signalling in accordance with at least some embodiments of the present invention, and

[0019] FIGURE 5 is a flow graph of a method in accordance with at least some embodiments of the present invention.

EMBODIMENTS

[0020] As disclosed herein below, a hierarchical network support function architecture may be used by requesting and responsively receiving information of a second network support function from a first network support function, which is of a same type as the first network support function. An example network support function is a network repository function. Information on the first network support function may be preconfigured in the requesting node, or the requesting node may construct this information based on a preconfigured scheme. The request may comprise a Nnrf NFDiscovery Get request or a Nnrf_NFManagement NFStatusSubscribe request, for example, where the system operates based on 3GPP specifications. Thus the requesting node need not be enabled to contact more than one, or more than a few, network support function(s) of the given type. This provides the beneficial effect that a hierarchical organization of network support nodes, for example network repository functions, NRFs, may be implemented. NRFs or other support nodes arranged in a hierarchical manner may be configured to process, for example, requests of increasingly large geographical scope as their rank in the hierarchy increases. For example, there may only be a handful of NFs of a rare type in the world, which can be discovered using a NRF with global scope or a regional NRF which handles larger geographical scope, for example in case the global NRF is only used for intermediate forwarding NRF between regional NRFs. Hierarchical NRF setups with regional and central/global NRFs can be realised either using intermediate redirecting or forwarding NRFs. Additionally or alternatively, multiple redundant (e.g. active-backup or active-active nodes with relative priority or weight) regional or global NRFs may be used for sharing NRF load for local NFs, or for providing fast failover in case one regional or global NRF fails or is taken out of use, e.g. for maintenance.

[0021] FIGURE 1 illustrates an example system in accordance with at least some embodiments of the present invention. The system comprises two public land mobile networks, PLMNs, 110, 112, each equipped with a network function, NF, 120, 122. A network function may refer to an operational and/or a physical entity. A network function may be a specific network node or element, or a specific function or set of functions carried out by one or more entities, such as virtualized network elements, VNFs. One physical node may be configured to perform plural NFs. Examples of such network functions include a (radio) access or resource control or management function, session management or control function, interworking, data management or storage function, authentication function or a combination of one or more of these functions.

[0022] In case of a third generation partnership project, 3GPP, 5G system service based architecture, SB A, core network, NFs may comprise at least some of an access and mobility function, AMF, a session management function, SMF, a network slice selection function, NSSF, a network exposure function, NEF, a network repository function, NRF, a unified data management, UDM, an authentication server function, AUSF, a policy control function, PCF, and an application function, AF. A further example is a user plane function, UPF, wherein an NRF may be used for dynamic registration of UPF services to NRF. Methods disclosed herein enable fast and/or automated provisioning of new UPF instances with regional scope when these NF nodes only need to resolve the local NRF instance(s) for registering the UPF services. The PLMNs each may further comprise a security edge protection proxy, SEPP, 130, 132 configured to operate as a security edge node or gateway. The NFs may communicate with each other using representational state transfer application programming interfaces. These may be known as Restful APIs.

[0023] The SEPP 130, 132 is a network node at the boundary of an operator's network that may be configured to receive a message, such as an HTTP request or HTTP response from the NF, apply protection for sending, and forward the reformatted message through a chain of intermediate nodes, such as IP exchanges, IPX, towards a receiving SEPP. The receiving SEPP receives a message sent by the sending SEPP and forwards the message towards an NF within its operator’s network, e.g. the AUSF.

[0024] An inter-PLMN interconnect allows secure communication between a service consuming NF and a service-producing NF, henceforth referred to as cNF 120 and pNF 122. They may also be referred to as NF service consumer and NF service producer, respectively.

[0025] A service communication proxy, SCP, 150 may be deployed for indirect communication between network functions. An SCP is an intermediate function/element to assist in routing messages, such as, for example, control plane messages between NFs.

[0026] Direct communication may be applied between cNF 120 and pNF 122 for an NF service, or NF service communication may be performed indirectly via SCP(s) 150. In direct communication, the cNF 120 performs discovery of the target pNF 122 by local configuration or via local NRF, cNRF 140. The cNF 120 may delegate the discovery of the target pNF 122 to the SCP 150 used for indirect communication. In the latter case, the SCP uses the parameters provided by cNF 120 to perform discovery and/or selection of the target NF Service producer. These parameters may include an identity or address of an NRF to contact first. The SCP address(es) for one or more SCP nodes may be locally configured in cNF 120, for example. Where multiple SCP nodes are used, they may serve redundancy and/or load sharing purposes, for example. In general, an SCP is an intermediate function covering delegated NF discovery to help resolving the target NF producer instances and delegated routing to help route control plane messages between two NFs.

[0027] NF discovery and NF service discovery enable core network entities, such as cNF or SCP, to discover a set of NF instance(s) and NF service instance(s) for a specific NF service or an NF type. The network repository function, NRF, is a function that is used to support the functionality of NF and NF service discovery and status notification. The NRF may maintain an NF profile of available NF instances and their supported services. The NRF may notify about newly registered, updated, or deregistered NF instances along with its NF services to a subscribed cNF or SCP. Unless the expected NF and/or NF service information is locally configured on the requester NF, such as when the expected NF service or NF is in the same PLMN as the requester NF, the NF and NF service discovery may be implemented via the NRF. The NRF is a logical function that is used to support the functionality of NF and NF service discovery. The NRF may also support status notification. An NRF may be co located together with an SCP, for example, run in a same computing substrate.

[0028] In order for the cNF 120 or SCP 150 to obtain information about the NF and/or NF service(s) registered or configured in a PLMN/slice, the cNF 120 or SCP 150 may initiate, based on local configuration, a discovery procedure with the cNRF 140. The discovery procedure may be initiated by providing the type of the NF and optionally a list of the specific service(s) it is attempting to discover. The cNF 120 or SCP 150 may also provide other service parameters, such as information relating to network slicing.

[0029] In case of indirect communication, during an NF service discovery in inter- PLMN (roaming) communication, the SCP 150, on behalf of the cNF 120, may request service discovery from a NRF in its PLMN 110, that is, cNRF 140. The cNRF may send a discovery request to an NRF, referred herein as pNRF 142, in another PLMN 112, e.g. the home PLMN. The pNRF 142 in the other network 112 may respond with a discovery response which may be forwarded to the SCP via the cNRF 140 in the PLMN 110 of the cNF. Then the SCP 150 may trigger service requests for the pNF 122 via the cSEPP 130 and the pSEPP 132. When using indirect communication, an cNF may provide the SCP an address or name of an NRF which may be used by the SCP.

[0030] An NF can communicate with a PLMN-level NRF by constructing an address for the NRF based on a predetermined process. Alternatively, the NRF address may be pre- configured in the NF in connection with initialization of the NF, or subsequently. For example, to obtain a fully qualified domain name of an NRF of a specific PLMN, a home network domain name of the PLMN may be prefixed by the letters “nrf The IP address may then be fetched from domain name server, DNS, for example. Similarly, an address, or name, of an NSSF, for example an NSSF of a different PLMN, may be self-constructed by an NF.

[0031] It is to be noted that at least some of the entities or nodes 120, 122, 130, 132, 140, 142 and 150 may act in both service-consuming and service-providing roles and that their structure may also be similar or identical, while their role in the present examples in delivery of a particular message is identified by use of the prefix “c” or “p” indicating whether they are acting for the service-consuming or service-producing NF. It is to be noted that instead of “c” and “p”, “v” for visited and “h” for home can be used to refer to at least some respective entities in the visited and home PLMNs.

[0032] In some embodiments OAuth based service authorization and token exchange is applied between the mobile networks. Thus, the second network entity, such as the pNRF, may be or perform an OAuth authorization server, AS. The cNF may be an OAuth client and the pNF may operate as OAuth resource server, and they may be configured to support OAuth authorization framework as defined in RFC 6749.

[0033] A method is herein described to handle dynamic NRF discovery when hierarchical NRF architectures are used for intra-domain (e)SBA, within a single PLMN, and inter-domain (e)SBA for 5GC roaming between visited and home PLMNs. In the following FIGURES 2A, 2B and 2C, scenarios are depicted where this method may be used.

[0034] In general, an NFc or SCP may store an identifier or address of a network support function assigned to a PLMN. The NFc or SCP may use this identifier or address to send a request message to a network support function assigned to the public land mobile network and to process a response message from the network support function assigned to the public land mobile network, the response message comprising information on one or more network support functions of a same type as the network support function assigned to the public land mobile network. The network support function may be an NRF, and the type of network support function may thus be the NRF. Responsive to the response message, the NFc or SCP may register itself with at least one of the network support functions that the response message comprises information on.

[0035] The request message may comprise an Nnrf_NFDiscovery request message. When this is the case, the request message may comprise at least one of the following parameters: a target network function type set to network repository function, a service name parameter set to network repository function authorisation, a preferred locality parameter set based on a locality of the apparatus which transmitted the request or a service communication proxy associated with the apparatus which transmitted the request, and the parameters may comprise prioritization information for use in selecting the information on one or more network support functions to include in the response message.

[0036] Concerning the service name parameter, it may be set for the Nnrf services that are sought via discovery, for example to “nnrf-nfm” for NnrfJNFManagement, “nnrf-disc” for Nnrf_NFDiscovery and/or “nnrf-oauth” or similar for Nnrf_AccesToken service APIs.

[0037] Concerning the preferred locality parameter, it may be set based on the locality of the requester NF consumer/producer instance, or based on an associated SCP-c and SCP-p instance, for example to prioritize the local NRF(s) in the search results.

[0038] Further possible parameters in the request message include a requester NF type and requester NF instance ID of the requesting entity. Another example of a possible parameter is a requester NF instance FQDN for the domain FQDN of the requester NF consumer/producer instance, or of an associated SCP-c and SCP-p instance. This may be included, for example, in case of delegated NF discovery by SCP-c this can be set to the value for the served NFc instance. Another possible parameter is a target NF set ID or target NF service set ID, when a specific NF Set or NF Service Set concept is defined for a group of local or redundant regional, or PLMN level central or global NRFs based on the locality of the requester NF consumer/producer instance, or an associated SCP-c and SCP-p instance, for example to prioritize the local NRF(s) based on the NF Set or NF Service Set concepts.

[0039] Additionally, for network slice specific NRF discovered via NSSF, the following query parameters may also be included by the requestor NF consumer/producer or network slice instance, NSI, specific SCP when different hierarchical NRF setups are used based on S-NSSAI / NSI information: nsnssais, requester-nsnssais and/or hnrf-uri in case that the cNF instance has received this API URI previously, for example via NSSF for network slice specific NRF in the home PLMN, and wants to discover the NRF topology to be used for this specific S-NSSAI / NSI.

[0040] In general, NRF service discovery responses may return an array of NF profile objects that satisfy the search filter criteria, which may be provided or indicated in the request message. For example, this may include all NF Instances offering a certain NF service name. In NRF discovery of NRFs, this is enhanced in the method described herein to return a list of NRFs that satisfy the search filter criteria. The list may be compiled to include only NRFs which are authorized to be used by the requester NF or SCP. Where NRFs are listed in the response, other NFs may or may not be listed in addition to the NRFs. For any further NF status updates for the previously-discovered (local) NRFs or local redundant NRFs, or any new dynamic NRF capacity extensions with newly added (local) NRFs, the requestor NF consumer/producer or SCP can subscribe to the NF status update notifications using Nnrf NFManagement Service API requests for this purpose, and to be able to dynamically update its local, NSI specific, NRF topology cache. In some embodiments, local NRF(s) can be selected using pre-configured information, for example with weight or a similar prioritization method.

[0041] On the other hand, the request message may comprise an Nnrf NFManagement subscribe request message, such as a NF status subscribe message. When this is the case, the request message may comprise at least one of the following parameters: a network function status notification parameter set to a callback uniform resource identifier, a network function type parameter set to a value corresponding to a network repository function, an network function instance identity set to at least one instance identifier of a network repository function in a network repository function cache of the apparatus transmitting the request, a service name parameter set to a service to be used via a network repository function and a network slice parameter set to request a network repository function topology for a specific network slice instance. Such parameters may be included as subscription data attribute “subscrCond” parameters, for example.

[0042] Concerning the network function status notification parameter, the callback uniform resource identifier may be one of the requester NFc, NFp or SCP instance/node for notifications by NRF(s).

[0043] Concerning the service name parameter, it may be set to the aimed to be used Nnrf services, such as nnrf-nfm for Nnrf_NFManagement, nnrf-disc for Nnrf_NFDiscovery and to a suitable value for Nnrf AccesToken Service APIs.

[0044] A further possible parameter is a NF set or NF service set parameter, when specific NF set or NF service set concept is defined for a group of local or redundant NRFs, based on the locality of the requester NF consumer/producer instance, or an associated SCP-c and SCP-p instance. This may be used to prioritize the local NRF(s) based on the NF set or NF service set concepts. [0045] Additionally, for network slice specific NRF discovered via NSSF, the following query parameters may also be included by the requestor NF consumer/producer or network slice instance, NSI, specific SCP when different hierarchical NRF setups are used based on S-NSSAI / NSI information: NetworkSliceCond in case that the NF consumer/producer instance wants to discover the NRF topology to be used for this specific S-NSSAI /NSI.

[0046] For further NF status updates for the previously-discovered NRFs or local redundant NRFs, or any new dynamic NRF capacity extensions with newly added NRFs, the requestor NF consumer/producer or SCP may receive NF status update notifications from the identified (matching) NRF resources, and it may be able to dynamically update its local, NSI specific, NRF topology cache based on updates. Also NF producers which currently have registered NF profiles and/or service instances to a specific local NRF instance may update their NRF cache for backup NRF instances in case that the original NRF fails. In some embodiments, NF producer instances do not need to register to multiple local, redundant, NRF instances.

[0047] In general, the request message and/or the response message may be compiled based on specifications established by 3GPP. In particular, the specifications may be fifth generation, 5G, specifications.

[0048] FIGURES 2A - 2D illustrate architectural options relevant to at least some embodiments of the present invention. In FIGURE 2A, an intra-PLMN, intra-domain SBA inter-SCP scenario is illustrated. NFc/SCP-c may contact NRF2a or NRF2b, based on a pre- configured or automatically generated address or domain name, to request information of NRF3. The requested information may comprise contact information, such as an address or domain name, of NRF3. NFc/SCP-c may then use NRF3 to discover NFp.

[0049] In FIGURE 2B, an inter-PLMN, inter-domain SBA, roaming scenario is illustrated for hierarchical NRF in a home PLMN. The NFc/SCP-c may contact vNRF or hNRF2a, for example, to request information, such as contact information, on hNRF3 in the home PLMN. hNRF2a may act as proxy. Inter-PLMN communication is effected via SEPPs and IPX, as illustrated. Using the illustrated architecture, roaming users do not need to be updated with or configured with contact information on plural NRFs, yet still enabling a hierarchical NRF architecture. [0050] In FIGURE 2C, an inter-PLMN, inter-domain SBA, roaming scenario is illustrated for hierarchical NRF in a visited PLMN. The NFc/SCP-c may contact vNRF2a or vNRF2b, for example, to request information, such as contact information, on vNRF3 in the visited PLMN. vNRF2a may act as proxy. Inter-PLMN communication is effected via SEPPs and IPX, as illustrated, to access the NFp which the NFc seeks to discover. Using the illustrated architecture, roaming users do not need to be updated with or configured with contact information on plural NRFs in visited PLMNs, yet still enabling a hierarchical NRF architecture. vNRF4 may act as an authentication server, for example as an OAuth AS. An NRF with authentication capability may be selected by an initial NRF contacted by NFc/SCP- c when the NFc/SCP-c indicates in the request that it seeks access to authentication. The situation of FIGURE 2C resembles that of FIGURES 2A and 2B, except here hierarchical intermediate forwarding NRF setups may be used in both PLMNs.

[0051] FIGURES 2D and 2E depict some examples for the potential topology options for hierarchical NRF: Central (Global)-Regional NRF clusters (DNS-like tree hierarchy) and Central (Global)-Regional NRF clusters (full mesh hierarchy), respectively. Additionally, a simpler topology with a single NRF cluster without Central (Global)-Regional separation can be possible.

[0052] FIGURE 2D illustrates a first hierarchical NRF topology, central -regional NRF clusters (DNS-like hierarchy). In this topology option, NRFs of regional clusters can share information, such as contact information, on other NRFs in their own cluster and the global cluster. However, NRFs of regional clusters do not in this topology option share information on NRFs of other regional clusters.

[0053] FIGURE 2E illustrates a second hierarchical NRF topology, central -regional NRF clusters in mesh connectivity. In this topology option, NRFs of regional clusters can share information on NRFs of at least some, and in some embodiments all, of the other regional clusters in addition to the global cluster.

[0054] In the topologies of FIGURE 2D and 2E, the global cluster is a set of NRFs which are configured as reachable from anywhere, and may share contact information of NFs located in any regional location. This is useful, for example, the enable discovery of NFs offering relatively rare services.

[0055] FIGURE 3 illustrates an example apparatus capable of supporting at least some embodiments of the present invention. Illustrated is device 300, which may comprise, for example, a node running a NF, NRF or SCP as herein described. Comprised in device 300 is processor 310, which may comprise, for example, a single- or multi-core processor wherein a single-core processor comprises one processing core and a multi-core processor comprises more than one processing core. Processor 310 may comprise, in general, a control device. Processor 310 may comprise more than one processor. Processor 310 may be a control device. A processing core may comprise, for example, a Cortex-A8 processing core manufactured by ARM Holdings or a Steamroller processing core designed by Advanced Micro Devices Corporation. Processor 310 may comprise at least one Qualcomm Snapdragon and/or Intel Atom processor. Processor 310 may comprise at least one application-specific integrated circuit, ASIC. Processor 310 may comprise at least one field-programmable gate array, FPGA. Processor 310 may be means for performing method steps in device 300, such as storing, transmitting and receiving. Processor 310 may be configured, at least in part by computer instructions, to perform actions.

[0056] A processor may comprise circuitry, or be constituted as circuitry or circuitries, the circuitry or circuitries being configured to perform phases of methods in accordance with embodiments described herein. As used in this application, the term “circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and/or digital circuitry, and (b) combinations of hardware circuits and software, such as, as applicable: (i) a combination of analog and/or digital hardware circuit(s) with software/firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a network function, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0057] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device. [0058] Device 300 may comprise memory 320. Memory 320 may comprise random- access memory and/or permanent memory. Memory 320 may comprise at least one RAM chip. Memory 320 may comprise solid-state, magnetic, optical and/or holographic memory, for example. Memory 320 may be at least in part accessible to processor 310. Memory 320 may be at least in part comprised in processor 310. Memory 320 may be means for storing information. Memory 320 may comprise computer instructions that processor 310 is configured to execute. When computer instructions configured to cause processor 310 to perform certain actions are stored in memory 320, and device 300 overall is configured to run under the direction of processor 310 using computer instructions from memory 320, processor 310 and/or its at least one processing core may be considered to be configured to perform said certain actions. Memory 320 may be at least in part comprised in processor 310. Memory 320 may be at least in part external to device 300 but accessible to device 300.

[0059] Device 300 may comprise a transmitter 330. Device 300 may comprise a receiver 340. Transmitter 330 and receiver 340 may be configured to transmit and receive, respectively, information in accordance with at least one cellular or non-cellular standard. Transmitter 330 may comprise more than one transmitter. Receiver 340 may comprise more than one receiver. Transmitter 330 and/or receiver 340 may be configured to operate in accordance with a suitable communication standard.

[0060] Device 300 may comprise user interface, UI, 360. UI 360 may comprise at least one of a display, a keyboard, a touchscreen, a vibrator arranged to signal to a user by causing device 300 to vibrate, a speaker and a microphone. A user may be able to operate device 300 via UI 360, for example to configure device 300 and/or functions it runs.

[0061] Processor 310 may be furnished with a transmitter arranged to output information from processor 310, via electrical leads internal to device 300, to other devices comprised in device 300. Such a transmitter may comprise a serial bus transmitter arranged to, for example, output information via at least one electrical lead to memory 320 for storage therein. Alternatively to a serial bus, the transmitter may comprise a parallel bus transmitter. Likewise processor 310 may comprise a receiver arranged to receive information in processor 310, via electrical leads internal to device 300, from other devices comprised in device 300. Such a receiver may comprise a serial bus receiver arranged to, for example, receive information via at least one electrical lead from receiver 340 for processing in processor 310. Alternatively to a serial bus, the receiver may comprise a parallel bus receiver. [0062] Device 300 may comprise further devices not illustrated in FIGURE 3. In some embodiments, device 300 lacks at least one device described above.

[0063] Processor 310, memory 320, transmitter 330, receiver 340 and/or UI 360 may be interconnected by electrical leads internal to device 300 in a multitude of different ways. For example, each of the aforementioned devices may be separately connected to a master bus internal to device 300, to allow for the devices to exchange information. However, as the skilled person will appreciate, this is only one example and depending on the embodiment various ways of interconnecting at least two of the aforementioned devices may be selected without departing from the scope of the present invention.

[0064] FIGURE 4A illustrates signalling in accordance with at least some embodiments of the present invention. On the vertical axes are disposed, on the left, NF service consumer NFc, NFp or SCP, and on the right, a PLMN-level NRF. Time advances from the top toward the bottom.

[0065] In phase 410, the NF service consumer transmits to the PLMN-level NRF a request message, which is in this embodiment based on the Nnrf NFDiscovery service. This request message has been described herein above. In phase 420, the PLMN-level NRF selects one of more NRFs that offer a service the consumer requested in phase 410. A search result is compiled based on the selection. The search result is provided to the NF service consumer in phase 430. In optional phase 440, the NF service consumer registers with the PLMN-level NRF. The NF service consumer may subsequently contact further NRF(s) to obtain through them discovery of the NF or NF service that the service consumer is seeking.

[0066] FIGURE 4B illustrates signalling in accordance with at least some embodiments of the present invention. On the vertical axes are disposed, on the left, NF service consumer NFc, NFp or SCP, and on the right, a PLMN-level NRF. Time advances from the top toward the bottom.

[0067] In phase 450, the NF service consumer transmits to the PLMN-level NRF a request message, which is in this embodiment a subscription request based on the Nnrf_NFManagement service. In phase 460, the PLMN-level NRF authorizes the subscription request and selects NRFs meeting criteria defined in the subscription request. In phase 470, subscription data of the selected NRFs is returned to the NF service consumer, and in phase 480 notification data is provided, for example concerning updates to the information of phase 470. In some embodiments, there is only one message of phases 470 and 480, informing the NF service consumer of the selection results. In phase 490 the NF service consumer selects an NRF from among the results received, and in phase 4100 connects to the selected one (or more) of the NRFs.

[0068] FIGURE 5 is a flow graph of a method in accordance with at least some embodiments of the present invention. The phases of the illustrated method may be performed in an NRF, for example. In detail, the phases of the method may be performed in an apparatus running an NRF. The apparatus, like other apparatuses running NFs, may comprise a single physical node or an arrangement of plural physical nodes together configured to run the NRF.

[0069] Phase 510 comprises storing information concerning plural network support functions of a same type as a network support function run in an apparatus performing the method. Phase 520 comprises receiving, from a network function or a service communication proxy, a request message. Finally, phase 530 comprises transmitting from the apparatus a response message, the response message comprising information on one or more network support functions of the same type as the network support function run in the apparatus.

[0070] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0071] Reference throughout this specification to one embodiment or an embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Where reference is made to a numerical value using a term such as, for example, about or substantially, the exact numerical value is also disclosed.

[0072] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.

[0073] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the preceding description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[0074] While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

[0075] The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", that is, a singular form, throughout this document does not exclude a plurality.

INDUSTRIAL APPLICABILITY

[0076] At least some embodiments of the present invention find industrial application in xxx.

ACRONYMS LIST

3 GPP third generation partnership project

5G fifth generation

5GC 5G core network

AF application function

AMF access and mobility function API application programming interface

AUSF authentication server function CN core network DNS domain name server DRA diameter routing agent HTTP hypertext transfer protocol FQDN fully qualified domain name IP Internet protocol IPX IP exchange NEF network exposure function NF network function NRF network repository function NSI network slice instance NSSF network slice selection function PCF policy control function PLMN public land mobile network SB A service based architecture SEPP security edge protection proxy SCP service communication proxy SMF session management function UDM unified data management

VNF virtualized network function

Claims

CLAIMS:

1. An apparatus comprising:

- a memory configured to store an identifier or address of a network support function assigned to a public land mobile network;

- at least one processing core configured to cause transmission, from the apparatus to the network support function assigned to the public land mobile network, of a request message and to process a response message from the network support function assigned to the public land mobile network, the response message comprising information on one or more network support functions of a same type as the network support function assigned to the public land mobile network.

2. An apparatus comprising:

- a memory configured to store information concerning plural network support functions of a same type as a network support function run in the apparatus;

- at least one processing core configured to receive, from a network function or a service communication proxy, a request message and to cause transmission, from the apparatus, of a response message, the response message comprising information on one or more network support functions of the same type as the network support function run in the apparatus.

3. The apparatus according to claim 1 or 2, wherein the network support function comprises a network repository function configured to perform network function discovery and/or network function service discovery.

4. The apparatus according to any of claims 1 - 3, wherein the request message comprises an Nnrf_NFDiscovery request message.

5. An apparatus according to any preceding claim, wherein the request message comprises at least one of the following parameters: a target network function type set to network repository function, a service name parameter set to network repository function authorisation, a preferred locality set based on a locality of the apparatus which transmitted the request or a service communication proxy associated with the apparatus which transmitted the request and prioritization information for use in selecting the information on one or more network support functions to include in the response message.

6. The apparatus according to any of claims 1 - 3, wherein the request message comprises an Nnrf_NFManagement subscribe request message.

7. The apparatus according to any of claims 1 - 3 or 6, wherein the request message comprises at least one of the following parameters: a network function status notification parameter set to a callback uniform resource identifier, a network function type parameter set to a value corresponding to a network repository function, an network function instance identity set to at least one instance identifier of a network repository function in a network repository function cache of the apparatus transmitting the request, a service name parameter set to a service to be used via a network repository function and a network slice parameter set to request a network repository function topology for a specific network slice instance.

8. The apparatus according to any preceding claim, wherein the request message and the response message are compiled based on specifications established by the third generation partnership project.

9. The apparatus according to claim 8, wherein the specifications are fifth generation specifications.

10. The apparatus according to claim 1, wherein the apparatus is configured to, responsive to the response message, register with at least one of the network support functions that the response message comprises information on.

11. A method comprising:

- storing an identifier or address of a network support function assigned to a public land mobile network;

- transmitting, from an apparatus to the network support function assigned to the public land mobile network, a request message, and - processing a response message from the network support function assigned to the public land mobile network, the response message comprising information on one or more network support functions of a same type as the network support function assigned to the public land mobile network.

12. A method comprising:

- storing information concerning plural network support functions of a same type as a network support function run in an apparatus performing the method;

- receiving, from a network function or a service communication proxy, a request message, and

- transmitting from the apparatus a response message, the response message comprising information on one or more network support functions of the same type as the network support function run in the apparatus.

13. The method according to claim 11 or 12, wherein the network support function comprises a network repository function configured to perform network function discovery and/or network function service discovery.

14. The method according to any of claims 11 - 13, wherein the request message comprises an Nnrf_NFDiscovery request message.

15. An method according to any of claims 11 - 14, wherein the request message comprises at least one of the following parameters: a target network function type set to network repository function, a service name parameter set to network repository function authorisation, a preferred locality set based on a locality of the apparatus which transmitted the request or a service communication proxy associated with the apparatus which transmitted the request and prioritization information for use in selecting the information on one or more network support functions to include in the response message.

16. The method according to any of claims 11 - 13, wherein the request message comprises an Nnrf_NFManagement subscribe request message.

17. The method according to any of claims 11 - 13 or 16, wherein the request message comprises at least one of the following parameters: a network function status notification parameter set to a callback uniform resource identifier, a network function type parameter set to a value corresponding to a network repository function, an network function instance identity set to at least one instance identifier of a network repository function in a network repository function cache of the apparatus transmitting the request, a service name parameter set to a service to be used via a network repository function and a network slice parameter set to request a network repository function topology for a specific network slice instance.

18. The method according to any of claims 11 - 17, wherein the request message and the response message are compiled based on specifications established by the third generation partnership project.

19. The method according to claim 18, wherein the specifications are fifth generation specifications.

20. The method according to claim 11, further comprising, responsive to the response message, registering with at least one of the network support functions that the response message comprises information on.

21. An apparatus comprising means for:

- transmitting, from an apparatus to the network support function assigned to the public land mobile network, a request message, and

- processing a response message from the network support function assigned to the public land mobile network, the response message comprising information on one or more network support functions of a same type as the network support function assigned to the public land mobile network.

22. An apparatus comprising means for: - storing information concerning plural network support functions of a same type as a network support function run in an apparatus performing the method;

23. A non-transitory computer readable medium having stored thereon a set of computer readable instructions that, when executed by at least one processor, cause an apparatus to at least:

- store an identifier or address of a network support function assigned to a public land mobile network;

- transmit, from the apparatus to the network support function assigned to the public land mobile network, a request message, and

- process a response message from the network support function assigned to the public land mobile network, the response message comprising information on one or more network support functions of a same type as the network support function assigned to the public land mobile network.

24. A non-transitory computer readable medium having stored thereon a set of computer readable instructions that, when executed by at least one processor, cause an apparatus to at least:

- store information concerning plural network support functions of a same type as a network support function run in the apparatus;

- receive, from a network function or a service communication proxy, a request message, and

- transmit from the apparatus a response message, the response message comprising information on one or more network support functions of the same type as the network support function run in the apparatus.

25. A computer program configured to cause, when executed, an apparatus to perform at least the following: - storing an identifier or address of a network support function assigned to a public land mobile network;

- transmitting, from the apparatus to the network support function assigned to the public land mobile network, a request message, and - processing a response message from the network support function assigned to the public land mobile network, the response message comprising information on one or more network support functions of a same type as the network support function assigned to the public land mobile network.

26. A computer program configured to cause, when executed, an apparatus to perform at least the following:

- storing information concerning plural network support functions of a same type as a network support function run in the apparatus;