# US 11,310,151 B2 · System and method for managing lookups for network repository functions > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,310,151 B2 - Document ID: US11310151B2 - Status: Granted - Kind: B2 - Application number: 16/571,404 - Filed: 2019-09-16 - Published: 2021-03-18 - Granted: 2022-04-19 - Earliest claimed: 2019-09-16 - Assignees: Verizon Patent and Licensing Inc. - Applicants: Verizon Patent and Licensing Inc. - Inventors: David Taft; Sudhakar Reddy Patil; Violeta Cakulev; Hossein M. Ahmadi - Web page: https://patentgrep.com/patent/US11310151B2 ## CPC - H04L 45/20: {Hop count for routing purposes, e.g. TTL} - H04W 24/02: Arrangements for optimising operational condition - H04L 1/0016: {involving special memory structures, e.g. look-up tables} - H04W 48/16: Discovering, processing access restriction or access information - H04W 84/042: {Public Land Mobile systems, e.g. cellular systems} - H04W 88/14: Backbone network devices - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Systems and methods manage lookups for network repository functions (NRFs). A network device, such as a NRF, receives a discovery request for a network function instance in a wireless core network. The discovery request includes a hop limit value. The network device determines if a result for the discovery request is available and determines if the hop limit value is greater than a stop value, when the result for the discovery request is not available. The network device forwards the discovery request to another network device when the result for the discovery request is not available and when the hop limit value is greater than the stop value. The network device sends a terminal response to the discovery request when the hop limit value is not greater than the stop value. ## Claims ### Claim 1 A method comprising: receiving, by a first Network Repository Function (NRF) device in a wireless core network, a discovery request submitted by a network function instance that is not an NRF, wherein the discovery request includes an HTTP GET message including an information element with a software-defined hop limit value, and wherein the hop limit value is determined based on a number of different NRF tiers in the wireless core network; determining, by the first NRF device, if information requested by the discovery request is available at the first NRF device; determining, by the first NRF device, if the hop limit value is greater than a stop value, when the information for the discovery request is not available; decrementing, by the first NRF device, the hop limit value in the discovery request when the information for the discovery request is not available and when the hop-limit value is greater than the stop value; forwarding, by the first NRF device, the discovery request with the decremented hop limit value to a second NRF device; and sending, by the first NRF device, a terminal response with the information to the network function instance when the hop-limit value is not greater than the stop value. ### Claim 2 (depends on 1) The method of claim 1, wherein sending the terminal response comprises: sending an error message that is responsive to the discovery request when the information for the discovery request is not available to the first NRF device. ### Claim 3 (depends on 1) The method of claim 1, wherein sending the terminal response comprises: sending a discovery answer that is responsive to the discovery request when the information for the discovery request is available to the first NRF device. ### Claim 4 (depends on 1) The method of claim 1, wherein the first NRF device includes an NRF instance for a Public Land Mobile Network (PLMN), and wherein the second NRF device includes an NRF instance for a network slice. ### Claim 5 (depends on 1) The method of claim 1, wherein the different NRF tiers in the wireless core network include a PLMN tier, a shared-slice tier, and a specific slice tier. ### Claim 6 (depends on 1) The method of claim 1, wherein receiving the discovery request includes: receiving the discovery request from one of an Access and Mobility Function (AMF), a Session Management Function (SMF), or a Policy Control Function (PCF) in the wireless core network. ### Claim 7 (depends on 1) The method of claim 1, wherein receiving the discovery request includes: receiving the discovery request via a Nnrf interface that is modified to support communication of the hop limit value. ### Claim 8 (depends on 1) The method of claim 1, wherein decrementing the hop limit value comprises changing the hop limit value in the information element of the discovery request. ### Claim 9 (depends on 1) The method of claim 1, wherein the discovery request is initiated by a third network device, the method further comprising: storing, by the third network device, the hop limit value for the discovery request. ### Claim 10 (depends on 9) The method of claim 9, further comprising: inserting, by the third network device, the hop limit value in the discovery request. ### Claim 11 A first Network Repository Function (NRF) device, comprising: a memory storing instructions; and a processor configured to execute the instructions to: receive a discovery request submitted by a network function instance that is not an NRF, wherein the discovery request includes an HTTP GET message including an information element with a software-defined hop limit value, and wherein the hop limit value is determined based on a number of different NRF tiers in the wireless core network; determine if information requested by the discovery request is available at the first NRF device; determine if the hop limit value is greater than a stop value, when the information for the discovery request is not available; decrement the hop limit value in the discovery request when the information for the discovery request is not available and when the hop-limit value is greater than the stop value; forward the discovery request with the decremented hop limit value to a second NRF device; and send a terminal response with the information to the network function instance when the hop-limit value is not greater than the stop value. ### Claim 12 (depends on 11) The first NRF device of claim 11, wherein, when sending the terminal response, the processor is further configured to execute the instructions to: send an error message that is responsive to the discovery request when the information for the discovery request is not available to the first NRF device. ### Claim 13 (depends on 11) The first NRF device of claim 11, wherein, when sending the terminal response, the processor is further configured to execute the instructions to: send a discovery answer that is responsive to the discovery request when the information for the discovery request is available to the first NRF device. ### Claim 14 (depends on 11) The first network device of claim 11, wherein the first NRF device includes an NRF instance for a single network slice within a Public Land Mobile Network (PLMN), and wherein the second NRF device includes an NRF instance for multiple slices within the PLMN network. ### Claim 15 (depends on 11) The first NRF device of claim 11, wherein the different NRF tiers in the wireless core network include a PLMN tier, a shared-slice tier, and a specific slice tier. ### Claim 16 (depends on 11) The first NRF device of claim 11, wherein, when receiving the discovery request, the processor is further configured to execute the instructions to: receive the discovery request via a Nnrf interface that is modified to support communication of the hop limit value. ### Claim 17 (depends on 11) The first NRF device of claim 11, wherein, when decrementing the hop limit value, the processor is further configured to execute the instructions to: change the hop limit value in the information element of the discovery request. ### Claim 18 A non-transitory computer-readable medium containing instructions executable by at least one processor, the computer-readable medium comprising one or more instructions to: receive a discovery request submitted by a network function instance that is not a Network Repository Function (NRF), wherein the discovery request includes an HTTP GET message including an information element with a software-defined hop limit value, and wherein the hop limit value is determined based on a number of different NRF tiers in the wireless core network; determine if a result for the discovery request is available at a first NRF device; determine if the hop limit value is greater than a stop value, when the information for the discovery request is not available; decrement the hop limit value in the discovery request when the information for the discovery request is not available and when the hop-limit value is greater than the stop value; forward the discovery request with the decremented hop limit value to a second NRF device; and send a terminal response with the information to the network function instance when the hop limit value is not greater than the stop value. ### Claim 19 (depends on 18) The non-transitory computer-readable medium of claim 18, wherein the different NRF tiers in the wireless core network include a PLMN tier, a shared-slice tier, and a specific slice tier. ### Claim 20 (depends on 18) The non-transitory computer-readable medium of claim 18, wherein the one or more instructions to send a terminal response to the discovery request comprise instructions to: send an error message that is responsive to the discovery request when the information for the discovery request is not available, and send a discovery answer that is responsive to the discovery request when the information for the discovery request is available.