Abstract: A method for providing for optimized service based interface (SBI) communications by performing network function (NF) fully qualified domain name (FQDN) resolution at an NF repository function (NRF) includes, at an NRF including at least one processor, receiving NF register requests including NF profiles and/or NF service profiles, at least some of which include FQDNs and do not include Internet protocol (IP) addresses. The method further includes storing the NF profiles and/or NF service profiles in an NF profiles database. The method further includes resolving the FQDNs in NF profiles and/or NF service profiles into IP addresses. The method further includes receiving NF discovery requests. The method further includes generating lists of NF profiles and/or NF service profiles that match query parameters in the NF discovery requests. The method further includes providing the lists of NF profiles and/or NF service profiles including the IP addresses to consumer NFs in NF discovery responses.

Abstract: A method for automatically triggering network slice selection assistance information (NSSAI) availability information updates with a network slice selection function (NSSF) includes receiving, from an access and mobility management function (AMF), a service request message. The method further includes determining, that the NSSAI availability information for the AMF is not present in an NSSAI availability information database maintained by the NSSF. The method further includes sending, to the AMF, a message for triggering the AMF to update its NSSAI availability information with the NSSF, receiving, an NSSAI Availability PUT request including NSSAI availability information for the AMF, and updating, the NSSAI availability information database to include the NSSAI availability information for the AMF.

Abstract: A method for processing NF discovery requests using prioritized lists of preferred locations includes maintaining an NF profiles database including NF profiles of producer NFs registered to provide service to other NFs and a preferred locality attribute mappings database including mappings between preferred locality attributes and prioritized lists of preferred locations. The method includes receiving, from an NF, an NF discovery request including query parameters and a preferred locality attribute. The method further includes accessing the preferred locality attribute mappings database using the preferred locality attribute and obtaining a prioritized list of preferred locations corresponding to the preferred locality attribute, accessing the NF profiles database using the query parameters and identifying NF profiles of producer NFs capable of providing a service indicated by the query parameters, and prioritizing the NF profiles according to the prioritized list of preferred locations.

Abstract: Methods, systems, and computer readable media for enabling forwarding of subsequent network function subscription updates. A method includes forwarding, from a bootstrapped network function repository function (NRF) in a first region, a subscription creation request from a consumer network function to a target NRF in a second region. The method includes creating, at the target NRF, a subscription for the consumer network function. The method includes generating, at the target NRF, a hint comprising data indicating one or more alternate NRFs each sharing subscription state data with the target NRF. The method includes sending, from the target NRF to the consumer network function, a subscription response message including the hint.

Abstract: A method for mitigating network function (NF) update and deregister attacks includes, at an NF repository function (NRF) implemented by at least one processor, receiving, from an NF, an NFRegister request including a hash of a first authentication string, an NF instance identifier, and an NF profile. The method further includes storing the hash of the first authentication string. The method further includes registering the NF by storing the NF profile in an NF profile database. The method further includes receiving a first NFUpdate or NFDeregister request including the NF instance identifier. The method further includes using the stored hash of the first authentication string to validate or reject the first NFUpdate or NFDeregister request.

Abstract: Methods, systems, and computer readable media for network function (NF) discovery using preferred-locality information are disclosed. One example method for NF discovery using preferred-locality information comprises: at a first NF comprising at least one processor: receiving a message relating to a transaction involving a consumer NF; identifying, from the message, an NF instance identifier (ID) corresponding to the consumer NF; determining, using the NF instance ID and a data store including NF related information and corresponding preferred-locality information, a preferred-locality value; including the preferred-locality value in a preferred-locality information element (IE) of an NF discovery request; and transmitting the NF discovery request toward a second NF.

Abstract: A method for managing NSSAI availability information at an NSSF includes receiving and storing NSSAI availability information from NF service consumers. The method further includes maintaining time values usable to determine expiration times for NSSAI availability information database records, where the time values are updated when a corresponding record is updated. The method further includes auditing the records, and, in response to failing to receive a request to update the NSSAI availability information for one of the NSSAI information database records within an expiration time, marking the record as stale. When a trigger is detected for providing NSSAI availability information from one of the database records that is marked as stale, the NSSF refrains from providing the NSSAI availability information to the NF service consumer.

Abstract: A method for automatic domain name system (DNS) configuration for 5G core (5GC) network functions (NFs) includes, at an NF repository function (NRF) including at least one processor, receiving a message concerning a 5GC network function. The method further includes determining a first DNS resource record parameter for the 5GC NF. The method further includes determining a second DNS resource record parameter for the 5GC NF. The method further includes automatically configuring a DNS with a mapping between the first and second DNS resource record parameters for the 5GC NF.

Abstract: A method for supporting configurable producer network function (NF) Internet protocol (IP) address mappings includes, at an NF repository function (NRF), receiving, from a requesting node, a request message for network address and/or service information of a producer NF. The method further includes determining, from the request message, at least one consumer NF parameter. The method further includes using the at least one consumer NF parameter, a producer NF IP address mapping rule. The method further includes, in response to locating the producer NF IP address mapping rule, determining, using the producer NF IP address mapping rule, an IP address to return to the requesting node. The method further includes generating a response message including the IP address and transmitting the response message to the requesting node.

Abstract: A method for routing inter-public land mobile network (inter-PLMN) messages relating to existing subscriptions with a network function (NF) repository functions (NRFs) includes, at a security edge protection proxy (SEPP) implemented using at least one processor, automatically populating, by the SEPP, a subscription identifier to target NRF resource identification information mapping database accessible to the SEPP with mappings between subscription identifiers and target NRF resource identification information. The method further includes receiving an inter-PLMN message for modifying or deleting a subscription. The method further includes reading a subscription identifier from the message for modifying or deleting the subscription. The method further includes using the subscription identifier from the message for modifying or deleting the subscription to access the database and obtain an identifier associated with an NRF that created the subscription.

Abstract: A method for facilitating processing of inter-public land mobile network (PLMN) messages relating to existing subscriptions includes receiving, at a first network function (NF) repository function (NRF), an inter-PLMN subscription creation request message for creating a subscription. The method further includes determining, by the first NRF, that the first NRF includes a resource for which the subscription is requested. The method further includes, in response to determining that the first NRF includes a resource for which the subscription is requested, generating, by the first NRF, a subscription creation response message indicating creation of the subscription. The first NRF includes, in the subscription creation response message, a hint indicating that the subscription is located on the first NRF and forwards the first NRF, the subscription creation response message towards a consumer NF.

Abstract: A method for providing for network function (NF) fallback to a recovered network function NF repository function (NRF) includes, at an NF including at least one processor, generating an NF register message including an indication to notify the NF of recovery of a first NRF after a failure of the first NRF. The method further includes transmitting the NF register message to the first NRF. The method further includes communicating with the first NRF and detecting failure of the first NRF. The method further includes, in response to detecting failure of the first NRF, initiating communications with a second NRF that is a geo-redundant mate of the first NRF. The method further includes receiving notification of recovery of the first NRF and falling back to communicating with the first NRF.

Abstract: Methods, systems, and computer readable media for identifying roaming messages at network functions in a home public land mobile network (PLMN). A method includes receiving, at a home security edge protection proxy (SEPP) for the home PLMN, a request message from a consumer network function in a visitor PLMN and adding, at the home SEPP, a header to the request message indicating that the request message originated in the visitor PLMN. The method includes receiving, at a producer network function in the home PLMN, the request message and determining, at the producer network function, that the request message originated in the visitor PLMN by finding the header indicating that the request message originated in the visitor PLMN. The method includes applying, at the producer network function, a roaming-specific policy while processing the request message in response to determining that the request message originated in the visitor PLMN.

Abstract: Methods, systems, and computer readable media for limiting network function (NF) repository function (NRF) forwarding are disclosed. One example method for limiting NRF forwarding comprises: at a first NF comprising at least one processor: receiving a request message associated with a consumer NF; determining that the request message cannot be serviced by the first NF; inserting or modifying a forwarding limit value in the request message, wherein the forwarding limit value indicates a number of times that the request message can be forwarded; and forwarding the request message including the forwarding limit value toward a second NF.

Abstract: Methods, systems, and computer readable media for discovering network function (NF) service producers in a hierarchical network are disclosed. One method includes receiving, by a regional NF repository function (NRF) operating in a first region of a hierarchical network, a NF registration request message from a NF service producer operating in the first region and detecting, by the regional NRF, an absence of <NF-Type>Info and/or <NF-Type>InfoList attribute data in the received NF registration request message.

Abstract: A method for supporting configurable producer network function (NF) Internet protocol (IP) address mappings includes, at an NF repository function (NRF), receiving, from a requesting node, a request message for network address and/or service information of a producer NF. The method further includes determining, from the request message, at least one consumer NF parameter. The method further includes using the at least one consumer NF parameter, a producer NF IP address mapping rule. The method further includes, in response to locating the producer NF IP address mapping rule, determining, using the producer NF IP address mapping rule, an IP address to return to the requesting node. The method further includes generating a response message including the IP address and transmitting the response message to the requesting node.

Abstract: Methods, systems, and computer readable media for network slice selection function (NSSF) recovery. A method includes creating, at an NSSF, subscriptions for a number of access and mobility management functions (AMFs) and storing availability information for each AMF. The method includes determining, at the NSSF, that the NSSF failed to process at least one service update message from at least one of the AMFs, and in response, sending a notification request message to each of the AMFs, the notification request message requesting each AMF to update availability information for the AMF. The method includes receiving, at the NSSF, updated availability information from each of the AMFs. The method includes distributing, at the NSSF, the updated availability information to each of the AMFs.

Abstract: A method for reducing inter-PLMN forwarding of messages relating to Nnrf service operations includes receiving, at a first NRF, a first request for an Nnrf service operation, determining that the first request identifies a PLMN different from a PLMN of the first NRF, determining that the first request cannot be processed locally at the first NRF, and, in response, forwarding the first request to a second NRF in the PLMN identified in the first request. The method further includes receiving , from the second NRF, a response to the first request, caching information from the response, receiving a second request for an Nnrf service operation, determining that the second request identifies a PLMN different from the PLMN of the first NRF, determining that the second request can be processed locally at the first NRF, and processing the second request locally at the first NRF using the cached information from the first response.

Abstract: Methods, systems, and computer readable media for enabling forwarding of subsequent network function subscription updates. A method includes forwarding, from a bootstrapped network function repository function (NRF) in a first region, a subscription creation request from a consumer network function to a target NRF in a second region. The method includes creating, at the target NRF, a subscription for the consumer network function. The method includes generating, at the target NRF, a hint comprising data indicating one or more alternate NRFs each sharing subscription state data with the target NRF. The method includes sending, from the target NRF to the consumer network function, a subscription response message including the hint.

Abstract: A method for supporting configurable producer network function (NF) Internet protocol (IP) address mappings includes, at an NF repository function (NRF), receiving, from a requesting node, a request message for network address and/or service information of a producer NF. The method further includes determining, from the request message, at least one consumer NF parameter. The method further includes using the at least one consumer NF parameter, a producer NF IP address mapping rule. The method further includes, in response to locating the producer NF IP address mapping rule, determining, using the producer NF IP address mapping rule, an IP address to return to the requesting node. The method further includes generating a response message including the IP address and transmitting the response message to the requesting node.