Method and apparatus for resolving domain names in the case of accessing a data network locally

Abstract

Exemplary embodiments generally relate to methods and apparatuses for resolving domain names in the case of local access to a data network. A method for resolving a domain name may include inserting an intermediate user plane function (I-UPF) in a data path of a packet data unit (PDU) session of a user equipment (UE) when a data network access identifier (DNAI) of the UE is detected to change, and configuring the I-UPF to forward a Domain Name System (DNS) query request from the UE to a DNS resolver along a path to a local packet data unit session anchor (PSA).

Description

Technical Field

[0001] Various exemplary embodiments generally relate to communication technologies, and more particularly, to methods and apparatuses for resolving domain names in the case of local access to a data network (DN). Background Art

[0002] Certain abbreviations that may be found in the description and / or drawings are defined herein as follows:

[0003] AMF Access and Mobility Management Function

[0004] AN Access Node

[0005] BP Branch Point

[0006] DHCP Dynamic Host Configuration Protocol

[0007] DN Data Network

[0008] DNAI DN Access Identifier

[0009] DNN Data Network Name

[0010] DNS Domain Name System

[0011] EAS Edge Application Server

[0012] FAR Forwarding Action Rule

[0013] FQDN Fully Qualified Domain Name

[0014] NAT Network Address Translator

[0015] NAS Non-Access Stratum

[0016] PDR Packet Detection Rule

[0017] PDU Packet Data Unit

[0018] PFCP Packet Forwarding Control Protocol

[0019] PSA PDU Session Anchor

[0020] SLACC Stateless Address Autoconfiguration

[0021] SMF Session Management Function

[0022] UE User Equipment

[0023] ULCL Uplink Classifier

[0024] UPF User Plane Function

[0025] Edge computing is supported in a 5G core network (5GC) to enable operators and third-party services to be hosted close to the access point to which a user equipment (UE) is attached, thereby enabling efficient service delivery with reduced end-to-end latency and load on the transport network. For example, a user plane function (UPF) close to the UE can be selected to route user traffic to a local data network (DN), and the 5GC can select to route traffic to an application in the local DN. To selectively route user traffic, a single packet data unit (PDU) session with multiple PDU session anchors (PSA) is used. SUMMARY OF THE INVENTION

[0026] A brief overview of exemplary embodiments is provided below to provide a basic understanding of some aspects of the various embodiments. It should be noted that this overview is not intended to identify key features of the essential elements or to limit the scope of the embodiments, and its sole purpose is to introduce some concepts in a simplified form as a preamble to provide a more detailed description below.

[0027] In a first aspect, an exemplary embodiment provides a method for resolving a domain name. The method may include: inserting an intermediate user plane function (I-UPF) in a data path of a packet data unit (PDU) session of a user equipment (UE) when a data network access identifier (DNAI) of the UE changes. The method may further include configuring the I-UPF to forward a domain name system (DNS) query request from the UE to a DNS resolver along a path to a local PDU session anchor (PSA).

[0028] In some embodiments, the step of configuring the I-UPF may include configuring the I-UPF with a packet detection rule (PDR) and a forwarding action rule (FAR) by a session management function (SMF). The packet detection rule (PDR) may be used to detect a packet from the UE using one of the following: a) a destination IP address matching the IP address of a DNS server previously communicated to the UE, b) a source IP prefix matching a first prefix associated with the local PSA, and c) a second prefix dedicated to a DNS query request. The forwarding action rule (FAR) may be used to forward the detected packet to the DNS resolver along a path to the local PSA.

[0029] In some embodiments, the method may further include sending a router advertisement (RA) message to the UE. The RA message may include: a) a first prefix associated with the local PSA and a DNS server configuration option associated with the first prefix, the DNS server configuration option including the address of the DNS resolver, or b) a second prefix dedicated to a DNS query request and a route information option (RIO) associated with the second prefix, the RIO including a route to the DNS resolver.

[0030] In some embodiments, the method may further include maintaining, at a session management function (SMF), an address of a DNS server communicated to a UE during a lifecycle of a PDU session of the UE.

[0031] In a second aspect, an exemplary embodiment provides a network device including at least one processor and at least one memory including computer program code. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the network device to at least perform the following steps: when detecting a change in a data network access identifier (DNAI) of a user equipment (UE), inserting an intermediate user plane function (I-UPF) in a data path of a packet data unit (PDU) session of the UE; and configuring the I-UPF to forward a domain name system (DNS) query request from the UE along a path to a local packet data unit session anchor (PSA) to a DNS resolver.

[0032] In some embodiments, the step of configuring the I-UPF may include configuring, by a session management function (SMF), the I-UPF with a packet detection rule (PDR) and a forwarding action rule (FAR). The PDR may be used to detect a packet from the UE having one of the following: a) a destination IP address matching an IP address of a DNS server previously communicated to the UE, b) a source IP prefix matching a first prefix associated with the local PSA, and c) a second prefix dedicated to a DNS query request. The FAR may be used to forward the detected packet along the path to the local PSA to the DNS resolver.

[0033] In some embodiments, the at least one memory and the computer program code may further be configured to, with the at least one processor, cause the network device to at least perform the following steps: sending a router advertisement (RA) message to the UE. The RA message may include: a) a first prefix associated with the local PSA and a DNS server configuration option associated with the first prefix, the DNS server configuration option including an address of a DNS resolver; or b) a second prefix dedicated to a DNS query request and a route information option (RIO) associated with the second prefix, the RIO including a route to the DNS resolver.

[0034] In some embodiments, the at least one memory and the computer program code may further be configured to, with the at least one processor, cause the network device to at least perform the following steps: maintaining, at a session management function (SMF), an address of a DNS server communicated to a UE during a lifecycle of a PDU session of the UE.

[0035] In a third aspect, an exemplary embodiment provides a communication device. The communication device may include: means for inserting an intermediate user plane function (I-UPF) in a data path of a packet data unit (PDU) session of a user equipment (UE) when a data network access identifier (DNAI) of the UE is detected to change; and means for configuring the I-UPF to forward a path query request along a path to a local packet data unit session anchor (PSA) from a domain name system (DNS) of the UE to a DNS resolver.

[0036] In some embodiments, the means for configuring the I-UPF includes means for configuring the I-UPF by a session management function (SMF) using a packet detection rule (PDR) and a forwarding action rule (FAR). The PDR may be used to detect a packet from the UE by using one of the following: a) a destination IP address matching an IP address of a DNS server previously communicated to the UE, b) a source IP prefix matching a first prefix associated with the local PSA, and c) a second prefix dedicated to a DNS query request. The FAR may be used to forward the detected packet along the path to the local PSA to the DNS resolver.

[0037] In some embodiments, the device may further include means for sending a router advertisement (RA) message to the UE. The RA message may include: a) a first prefix associated with the local PSA and a DNS server configuration option associated with the first prefix, the DNS server configuration option including a DNS resolver address, or b) a second prefix request dedicated to a DNS query and a routing information option (RIO) associated with the second prefix, the RIO including a route to the DNS resolver.

[0038] In some embodiments, the device may further include means for maintaining, at a session management function (SMF), an address of a DNS server communicated to the UE during a lifecycle of a PDU session of the UE.

[0039] In a fourth aspect, an exemplary embodiment provides a method for resolving a domain name, which includes: receiving a packet forwarding control protocol (PFCP) configuration from a session management function (SMF); and forwarding a domain name system (DNS) query request from the session management function (SMF) to a DNS resolver along a path to a local packet data unit session anchor (PSA) according to the PFCP configuration.

[0040] In some embodiments, the PFCP configuration includes: a Packet Detection Rule (PDR) for detecting packets from a UE using one or more of the following options: a) a destination IP address matching the IP address of a DNS server previously communicated to the UE, b) a source IP prefix matching a first prefix associated with the local PSA, and c) a second prefix dedicated to DNS query requests; and a Forwarding Action Rule (FAR) corresponding to one or more of the following forwarding actions: a) forwarding the packet to a local PSA associated with a specific local network, b) forwarding the packet to a local PSA co-located with a Network Address Translator (NAT) having a local network specific address pool, c) forwarding the packet to be processed by a DNS forwarder resolver co-located at the I-UPF or local PSA.

[0041] In some embodiments, the DNS resolver is a local DNS resolver serving the local PSA.

[0042] In some embodiments, the local DNS resolver is configured to: respond to a DNS query request in the case where the local DNS resolver serves as the authoritative DNS server for the domain name included in the DNS query request; or forward the DNS query request to a higher-level DNS server after filling the DNS subnet option of the DNS query request with the IP address or subnet specific to the edge network associated with the local PSA.

[0043] In some embodiments, before routing the DNS query request to the DNS resolver, the source IP address of the DNS query request is changed by a Network Address Translator (NAT) co-located with the local PSA to an address specific to the edge network associated with the local PSA.

[0044] In some embodiments, the DNS resolver is configured to: respond to a DNS query request in the case where the DNS resolver serves as the authoritative DNS server for the domain name included in the DNS query request; or forward the DNS query request to a higher-level DNS server after filling the DNS subnet option of the DNS query request with the full or truncated source IP address of the DNS query request.

[0045] In some embodiments, before routing the DNS query request to the DNS resolver, the DNS subnet option of the DNS query request is filled by a DNS forwarder co-located with the I-UPF and / or the local PSA with the IP address or subnet specific to the edge network associated with the local PSA.

[0046] In some embodiments, before routing a DNS query request to a DNS resolver, the DNS subnet option of the DNS query request is resolved by a DNS forwarder resolver co-located with the I-UPF and / or the local PSA with an IP address or subnet specific to the edge network associated with the local PSA, and / or the source IP address of the DNS query request is changed by the DNS forwarder resolver to the address of the DNS forwarder resolver.

[0047] In some embodiments, the DNS resolver is configured to: respond to a DNS query request if the DNS resolver serves as the authoritative DNS server for the domain name included in the DNS query request; or forward the DNS query request to a higher-level DNS server.

[0048] In a fifth aspect, an exemplary embodiment provides a network device, including: at least one processor; at least one memory including computer program code, the at least one memory and the computer program code being configured to, by using the at least one processor, cause the network device to at least perform the following steps: receive a Packet Forwarding Control Protocol (PFCP) configuration from a Session Management Function (SMF); and forward a Domain Name System (DNS) query request from a User Equipment (UE) along a path to a local Packet Data Unit Session Anchor (PSA) to a DNS resolver according to the PFCP configuration.

[0049] In some embodiments, the PFCP configuration includes: a Packet Detection Rule (PDR) for detecting packets from the UE by adopting one or more of the following options: a) a destination IP address matching the IP address of a DNS server previously communicated to the UE, b) a source IP prefix matching a first prefix associated with the local PSA, and c) a second prefix dedicated to the DNS query request; and a Forwarding Action Rule (FAR) corresponding to one or more of the following forwarding actions: a) forwarding the packet to a local PSA associated with a specific local network, b) forwarding the packet to a local PSA co-located with an Address Translator (NAT) having a local network-specific address pool, c) forwarding the packet to be processed by a DNS forwarder resolver co-located at the I-UPF or the local PSA.

[0050] In some embodiments, the DNS resolver is a local DNS resolver serving the local PSA.

[0051] In some embodiments, the local DNS resolver is configured to: respond to a DNS query request if the local DNS resolver serves as the authoritative DNS server for the domain name included in the DNS query request; or forward the DNS query request to a higher-level DNS server after populating the DNS subnet option of the DNS query request with an IP address or subnet specific to the edge network associated with the local PSA.

[0052] In some embodiments, before routing a DNS query request to a DNS resolver, the source IP address of the DNS query request is changed by a network address translator (NAT) co-located with the local PSA to an address specific to the edge network associated with the local PSA.

[0053] In some embodiments, the DNS resolver is configured to: respond to the DNS query request in the case where the DNS resolver serves as the authoritative DNS server for the domain name included in the DNS query request; or forward the DNS query request to a higher-level DNS server after filling the DNS subnet option of the DNS query request with the full or truncated source IP address of the DNS query request.

[0054] In some embodiments, before routing a DNS query request to a DNS resolver, the DNS subnet option of the DNS query request is filled by a DNS forwarder co-located with the I-UPF and / or the local PSA with an IP address or subnet specific to the edge network associated with the local PSA.

[0055] In some embodiments, before routing a DNS query request to a DNS resolver, the DNS subnet option of the DNS query request is filled by a DNS forwarder resolver co-located with the I-UPF and / or the local PSA with an IP address or subnet specific to the edge network associated with the local PSA, and / or the source IP address of the DNS query request is changed by the DNS forwarder resolver to the address of the DNS forwarder resolver.

[0056] In some embodiments, the DNS resolver is configured to: respond to the DNS query request in the case where the DNS resolver is the authoritative DNS server for the domain name included in the DNS query request; or forward the DNS query request to a higher-level DNS server.

[0057] In a sixth aspect, an exemplary embodiment provides a communication device, including: means for receiving a Packet Forwarding Control Protocol (PFCP) configuration from a Session Management Function (SMF); and means for forwarding a Domain Name System (DNS) query request from a User Equipment (UE) to a DNS resolver along a path to a local Packet Data Unit Session Anchor (PSA) according to the PFCP configuration.

[0058] In some embodiments, the PFCP configuration includes: a Packet Detection Rule (PDR) for detecting packets from a UE using one or more of the following options: a) a destination IP address matching the IP address of a DNS server previously communicated to the UE, b) a source IP prefix matching a first prefix associated with the local PSA, c) a second prefix dedicated to DNS query requests; and a Forwarding Action Rule (FAR) corresponding to one or more of the following forwarding actions: a) forwarding the packet to a local PSA associated with a specific local network, b) forwarding the packet to a local PSA co-located with an Address Translator (NAT) having a local network specific address pool, c) forwarding the packet to be processed by a DNS forwarder resolver co-located at the I-UPF or the local PSA.

[0059] In some embodiments, the DNS resolver is a local DNS resolver serving the local PSA.

[0060] In some embodiments, the local DNS resolver is configured to: respond to a DNS query request in the case where the local DNS resolver serves as the authoritative DNS server for the domain name included in the DNS query request; or forward the DNS query request to a higher-level DNS server after filling the DNS subnet option of the DNS query request with an IP address or subnet specific to the edge network associated with the local PSA.

[0061] In some embodiments, before routing the DNS query request to the DNS resolver, the source IP address of the DNS query request is changed by a Network Address Translator (NAT) co-located with the local PSA to an address specific to the edge network associated with the local PSA.

[0062] In some embodiments, the DNS resolver is configured to: respond to a DNS query request in the case where the DNS resolver serves as the authoritative DNS server for the domain name included in the DNS query request; or forward the DNS query request to a higher-level DNS server after filling the DNS subnet option of the DNS query request with the full or truncated source IP address of the DNS query request.

[0063] In some embodiments, before routing the DNS query request to the DNS resolver, the DNS subnet option of the DNS query request is filled by a DNS forwarder co-located with the I-UPF and / or the local PSA with an IP address or subnet specific to the edge network associated with the local PSA.

[0064] In some embodiments, before routing a DNS query request to a DNS resolver, the DNS subnet option of the DNS query request is resolved by a DNS forwarder resolver co-located with the I-UPF and / or the local PSA and filled with an IP address or subnet specific to the edge network associated with the local PSA, and / or the source IP address of the DNS query request is changed by the DNS forwarder resolver to the address of the DNS forwarder resolver.

[0065] In some embodiments, the DNS resolver is configured to: respond to a DNS query request in case the DNS resolver serves as an authoritative DNS server for the domain name included in the DNS query request; or forward the DNS query request to a higher-level DNS server.

[0066] In a seventh aspect, an exemplary embodiment provides a computer-readable medium having instructions stored thereon, which when executed by at least one processor of a device cause the device to perform any of the above methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Some example embodiments will now be described by way of non-limiting examples with reference to the accompanying drawings.

[0068] Figure 1 A schematic architecture diagram of a 5G system having an edge application server (EAS) hosted in a data network is shown;

[0069] Figure 2 A schematic block diagram of a network according to an exemplary embodiment is shown.

[0070] Figure 3 A process of domain name resolution according to an exemplary embodiment is shown.

[0071] Figure 4 A schematic block diagram of a network according to an exemplary embodiment is shown.

[0072] Figure 5 A process of domain name resolution according to an exemplary embodiment is shown.

[0073] Figure 6 A schematic block diagram of a network according to an exemplary embodiment is shown.

[0074] Figure 7 A process of domain name resolution according to an exemplary embodiment is shown.

[0075] Figure 8 A block diagram of a network device according to an exemplary embodiment is shown.

[0076] Figure 9 A block diagram of a communication device according to an exemplary embodiment is shown.

[0077] Figure 10 A block diagram of a network device according to an exemplary embodiment is shown.

[0078] Figure 11 A block diagram of a communication device according to an exemplary embodiment is shown.

[0079] Throughout the drawings, the same or similar reference numerals denote the same or similar elements. A repeated description of the same elements will be omitted. Detailed implementation manners

[0080] Hereinafter, some example embodiments will be described in detail with reference to the drawings. To provide a thorough understanding of the various concepts, the following description includes specific details. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some cases, well-known circuits, techniques, and components are shown in block diagram form to avoid obscuring the concepts and features being described.

[0081] Figure 1 The 5G system 100 is schematically shown. Generally, the exemplary embodiments discussed below may be implemented in or in conjunction with the 5G system 100.

[0082] Reference Figure 1 , the user equipment (UE) 101 is connected to the 5G network at an access node (AN) 102 such as a base station gNB, and then connected to the data network through the 5G network. The DN 108 may be, for example, the Internet, where multiple edge application servers (EAS) 109 may be deployed.

[0083] In the user plane, the UE 101 is connected to user plane functions (UPF) including an intermediate UPF (I-UPF) 103, a local UPF (L-UPF) 104, and a central UPF (C-UPF) 105. The 5G system separates the user plane functions from the control plane functions to enable flexible and customizable deployment of the UPF. The central UPF 105 may be deployed in a centralized location, and the local UPF 104 may be deployed in a distributed location close to the UE 101, each providing access to the DN108 through the N6 interface (also referred to as a "reference point" or "reference interface"). The packet data unit (PDU) exchange between the UE 101 and the DN108 identified by a data network name (DNN) is supported through a PDU session established between them. As Figure 1As shown, the PDU session of UE 101 can correspond to two N6 interfaces to DN 108 at the same time. The UPFs 104 and 105 terminating at the N6 interface are called PDU session anchors (PSA) or PSA UPFs. The I-UPF 103 is inserted before the local UPF 104 and the central UPF 105 and is connected to the local UPF 104 and the central UPF 105 via the N9 interface. The I-UPF 103 can act as an uplink classifier (ULCL) or a branching point (BP) to selectively route packets from the UE 101 to the local UPF 104 or the central UPF 105. In some embodiments, the I-UPF 103 can also act as the local PSA 104 and / or be co-located with the local PSA 104. The I-UPF 103 is connected to the AN 102 via the N3 interface.

[0084] In the control plane, the session management function (SMF) 106 can manage the PDU session of the UE 101 by controlling the UPFs 103, 104, and 105. The SMF 106 can interact with the UPFs 103, 104, and 105 on the N4 interface. For example, the SMF 106 can select the L-UPF 104 for PDU session establishment or relocation through the N4 session establishment process. The SMF 106 can also decide to insert the UPF 103 supporting the ULCL or BP function into the data path of the PDU session of the UE 101 during or after PDU session establishment, or remove the UPF supporting the PDU session or BP function from the data path of the PDU session after PDU session establishment. The access and mobility management function (AMF) 107 is connected to the UE 101, the AN 102, and the SMF 106 via the N1 interface, the N2 interface, and the N11 interface respectively. The AMF 107 can be a network function that processes various connection and mobility management tasks. For example, the AMF 107 can report the reachability or mobility events of the UE to the SMF 106.

[0085] The edge application server (EAS) 109 can be deployed in the DN 108 to serve application services. The EAS 109 can include multiple instances that host the same content or service and are deployed at different sites / locations. Before the UE 101 starts connecting to the service, it is important for the UE 101 to discover the IP address of a suitable EAS instance closest to the UE 101 so that traffic can be routed locally to the EAS, and service latency, traffic routing path, and user service experience can be optimized. This can be easily achieved through the Internet because when the authoritative domain name system (DNS) server receives a DNS query with a specific IP address / subnet associated with the client location from the client, the authoritative DNS server will return the IP address of the service server closest to the client location.

[0086] However, for a 5G network, the IP address of a UE does not reveal any information about its location. In particular, the IP address (or IPv6 prefix) of UE 101 is only associated with the central PSA 105. Even when UE 101 is located at a position where it has local access through local PSA 104 to DN 108, the central DNS resolver (not shown) behind the central PSA 105 has no knowledge of the UE's current location. Therefore, the authoritative DNS server is also unable to obtain information about the location of the UE or the location of the local PSA / edge network to which the UE is connected, and is unable to provide a translation from the fully qualified domain name (FQDN) of the service to the EAS located near the UE.

[0087] To address the above and other challenges, the exemplary embodiments described herein provide a DNS resolution mechanism that takes into account the location information of the UE. The exemplary embodiments can utilize the location information of the UE to ensure that DNS queries are accurately mapped to the IP address of the service server closest to the UE, thereby improving service latency, traffic routing, and user service experience.

[0088] Figure 2 A schematic block diagram of a network 200 according to an exemplary embodiment is shown. In the drawings, the same or similar components are denoted by the same or similar reference numerals or numbers, and their repeated description will be omitted. In one or more of the drawings, for the sake of brevity and to avoid redundant description thereof, some components shown in other drawings may be omitted. Referring Figure 2 , UE 101 has local access through local PSA 104 to DN 108 ( Figure 1 ) and central access through central PSA 105 to DN 108 ( Figure 1 ). The intermediate UPF 103 is used to selectively route traffic from UE 101 to local PSA 104 or central PSA 105.

[0089] In network 200, the local DNS resolver 110 is deployed behind the local PSA 104 to process DNS query requests from UE 101 through local PSA 104. The local DNS resolver 110 is locally deployed together with the local PSA and dedicated to the local PSA 104, and it knows the IP address or IP subnet of the local PSA 104 or the edge network where the local PSA 104 is deployed. The central DNS resolver 111 is centrally deployed behind the central PSA 105. The local DNS resolver 110 and the central DNS 111 can act as, for example, fully recursive resolvers, and they are both connected to a higher-level DNS resolver, such as connected to the authoritative DNS server 112. In one example, the local DNS resolver 110 can be connected to the central DNS resolver 111.

[0090] Figure 3 shows the process 300 of domain name resolution according to an exemplary embodiment. The process 300 can be executed in the Figure 2 network 200 shown in.

[0091] Referring to Figure 3 , at 302, the SMF 106 maintains information on the DNS server IP address communicating with the UE 101. The DNS server IP address can be transmitted to the UE 101 through NAS signaling or a DHCP-based method. The SMF 106 can store the DNS server IP address communicated to the UE 101 during the life cycle of the UE PDU session.

[0092] At 304, when it is detected that the data network access identifier (DNAI) of the UE 101 changes, the SMF 106 inserts the intermediate UPF 103 into the data path of the PDU session of the UE 101. The DNAI is an identifier for the user plane to access the DN 108 where the EAS 109 is deployed, and it can be understood as an access point to the EAS 109 in the DN 108. As is well known, the 5G network provides multiple access points to the same DN 108. When the UE 101 moves from the first location to the second location within the 5G network, the DNAI of the UE 101 can change from the first DNAI to the second DNAI. In addition, when the UE106 initially connects to the 5G network and obtains local access associated with the DNAI for the DN 108, it can also be regarded as a change in the DNAI of the UE101. The SMF 106 can decide to insert the I-UPF 103 when it detects a change in the DNAI of the UE 101, including the DNAI change caused by UE mobility and new DNAI allocation.

[0093] At 306, the SMF 106 can use the Packet Forwarding Control Protocol (PFCP) configuration to configure the I-UPF 103 so that the I-UPF 103 forwards the DNS query request from the UE 101 to the local DNS resolver 110 along the path to the local PSA 104. The PFCP configuration of the I-UPF 103 can include a Packet Detection Rule (PDR) for detecting packets from the UE 101 or especially DNS query packets, and a Forwarding Action Rule (FAR) for forwarding the detected packets.

[0094] In the case where the PDU session of UE 101 is of IPv4, IPv6, IPv4v6, or Ethernet type, I-UPF 103 can be used as an uplink classifier (ULCL) and SMF 106 can configure I-UPF 103 with a PDR to detect packets from UE 101 that have a destination IP address matching the IP address of the DNS server previously communicated to UE 101. As discussed above with reference to step 302, SMF 106 can maintain information on the DNS server IP address communicated to UE 101 via NAS signaling or the DHCP method. When UE 101 sends a DNS query request addressed to the DNS server, I-UPF 103 can detect the DNS query request packet by using the PDR configured by SMF 106.

[0095] In the case where the PDU session of UE 101 is of IPv6 or IPv4v6 type, I-UPF 103 can be used as a branch point (BP) and SMF 106 can configure I-UPF 103 with a PDR to detect packets from UE 101 that have a specific IPv6 prefix previously communicated to UE 101. In some embodiments, SMF 106 can send an IPv6 router advertisement (RA) message having an IPv6 prefix associated with the local PSA 104. The RA message can also include a DNS server configuration option that provides a high priority to a DNS resolver, such as the local DNS resolver 110. Via the RA message, UE 101 sends its DNS query request to the local DNS resolver 110 associated with the local PSA 104, and I-UPF 103 can detect the DNS query request packet by using the PDR configured by SMF 106. In some other embodiments, the RA message can include an IPv6 prefix dedicated to the DNS query request, as well as a routing information option (RIO) associated with the IPv6 prefix and thus associated with the DNS query request. The RIO can include a route to a DNS resolver such as the local DNS resolver 110. With the RA message, UE 101 sends its DNS query request with the dedicated IPv6 prefix and routing information to the local DNS resolver 110, and I-UPF 103 can detect the DNS query request packet by using the PDR configured by SMF 106.

[0096] The FAR configured by the SMF 106 for the I-UPF 103 specifies how to forward the detected packets. In this embodiment, the detected packets will be forwarded along the path to the local PSA 104 to the local DNS resolver 110. It can be implemented, for example, by anycast, IP tunneling, etc. In some embodiments, the destination address of the DNS query request can be changed to the local DNS resolver 110, so that the DNS query request is forwarded to the local DNS resolver 110 via the local PSA 104. In this case, the source IP address of the returned packet will change back from the local DNS resolver 110 to the destination address. In some other embodiments, the FAR can be configured to only forward the DNS query request to the local DNS resolver 110 via the local PSA 104 without changing the destination address of the DNS query request.

[0097] At 308, the UE 101 will issue a DNS query request with a source IP address and a destination IP address. The source IP address can be the IP address of the UE provided by the central PSA 105, or include the IPv6 prefix received from the SMF 106 in the RA message. The destination IP address can be a DNS server provided by NAS signaling or a DHCP-based method, such as the central DNS resolver 105, or the local DNS resolver 110 provided in the RA message. In some embodiments, the DNS query request may also include the routing information for the local DNS resolver 110 provided in the RA message.

[0098] At 310, the I-UPF 103 detects the DNS query request from the UE 101 and forwards the DNS query request to the local DNS resolver 110 along the path to the local PSA 104 according to the PFCP configuration received from the SMF 106. As described above, the I-UPF 103 can detect packets from the UE 101 that have a destination IP address matching the IP address of the DNS server previously communicated to the UE 101, or a source IP prefix matching the IPv6 prefix associated with the local PSA previously sent to the UE 101 in the RA message, or a source IP prefix matching the IPv6 prefix dedicated to the DNS query request previously sent to the UE 101 in the RA message. In Figure 2 the illustrated embodiment, the detected packets will be forwarded by the I-UPF 103 to the local DNS resolver 110 via the local PSA 104.

[0099] At 312, the DNS query request is processed at the local DNS resolver 110. If the domain name to be resolved included in the DNS query request can be directly resolved by the local DNS resolver 110, or in other words, if the local DNS resolver 110 can act as the authoritative name server for the domain name to be resolved, the local DNS resolver 110 will respond to the DNS query request with the IP address of the serving server. Since the local DNS resolver 110 knows the IP address of the local PSA or the local edge network associated with the local PSA, it knows the location of the UE 101 and will use the serving server closest to the UE 101 to respond to the DNS query request. On the other hand, if the local DNS resolver 110 cannot resolve the domain name to be resolved included in the DNS query request, after filling the DNS subnet option of the DNS query request with the IP address or subnet of the local PSA 104 or the local edge network, the DNS query request is forwarded to a higher-level DNS server. The DNS subnet option can be filled with the full or truncated IP of the local PSA 104. The truncated IP address can be formed by taking any number of the most significant bits of the IP address while transforming the remaining bits of the IP address to zero. The local DNS resolver 110 can act as a recursive resolver and forward the DNS query request to the authoritative DNS server 112, or forward it to the central DNS resolver 111 and then, if necessary, forward it to the authoritative DNS server 112.

[0100] Figure 4 Fig. 400 shows a network 400 according to an exemplary embodiment. Components in the network 400 that are the same as or similar to those in the above embodiments will be denoted by the same or similar reference numerals, and repeated descriptions thereof will be omitted.

[0101] In network 400, instead of the local DNS resolver 110, a Network Address Translator (NAT) 113 and a DNS resolver 114 are provided. The NAT 113 can be co-located with the local PSA 104, and it can have a local edge network specific address pool. When a DNS query request is routed to the local PSA 104, the NAT 113 changes the IP source address of the DNS query request from the IP address allocated to the UE set to a local edge network specific address. Thus, the DNS resolver 114 can map the DNS query request to a specific local edge network. Different from the local DNS resolver 110 which is locally deployed to only serve the local PSA 104 and operates based on the local context, the DNS resolver 114 can serve multiple local edge networks. The DNS resolver 114 does not need to be locally deployed in the edge network associated with the local PSA 104, and it can be a Remote DNS (R-DNS) resolver. The DNS resolver 114 can also be locally deployed in the edge network associated with the local PSA 104, but it does not need to operate based on the local context. Since the NAT 113 has changed the source IP address of the DNS query request to a local edge network specific address, the remote DNS resolver 114 knows where the DNS query request comes from, that is, where the UE 101 is located, even without the local context.

[0102] Figure 5 FIG. 500 shows a process of domain name resolution according to an exemplary embodiment. The process 500 can be executed in Figure 4 the network 400 shown. In the process 500, steps that are the same as or similar to those in Figure 3 the process 300 shown are numbered with the same or similar step numbers, and their repeated descriptions will be omitted.

[0103] At 510, the I-UPF 103 detects a DNS query request from the UE 101 and forwards the DNS query request to the DNS resolver 114 via the local PSA 104 according to the PFCP configuration received from the SMF 106.

[0104] At 512, when the DNS query request is routed to the local PSA 104 co-located with the NAT 113, the NAT 113 converts the IP source address of the DNS query request from the IP address allocated to the UE to an address specific to the local edge network, such as a local PSA specific address.

[0105] Then, at 514, the DNS resolver 114 processes the DNS query request. If the DNS resolver 114 can act as the authoritative name server for the domain name to be resolved, it will use the IP address of the serving server closest to the UE 101 to respond to the DNS query request because it knows the location of the UE 101. On the other hand, if the DNS resolver 114 cannot resolve the domain name to be resolved included in the DNS query request, after filling the DNS subnet option of the DNS query request with the full or truncated IP address of the DNS query request, it forwards the DNS query request to a higher-level DNS server. The DNS resolver 114 can act as a recursive resolver and forward the DNS query request to the authoritative DNS server 112, or to the central DNS resolver 111 and then, if necessary, to the authoritative DNS server 112.

[0106] Figure 6 FIG. shows a network 600 according to an exemplary embodiment. Components that are the same or similar to those in the above embodiment in the network 600 will be denoted by the same or similar numbers, and repeated descriptions thereof will be omitted.

[0107] Reference Figure 6, instead of the local DNS resolver 110 or the remote DNS resolver 114, a DNS forwarder 115 is provided. The DNS forwarder 115 can be co-located with the I-UPF 103 and / or the L-PAS 104. As described above, the I-UPF 103 and the L-PAS 104 can be co-located with each other. In this embodiment, the SMF 106 can configure the I-UPF 103 to forward DNS query requests from the UE 101 to the DNS forwarder 115, the local PSA 104, and then to the central DNS resolver 111. Since the DNS forwarder 115 is deployed locally with the I-UPF 103 and the local PSA 104, it can operate based on the local context. In some embodiments, the DNS forwarder 115 can use an IP address or a subnet to fill the DNS subnet option of the DNS query request, and the IP address or subnet is specific to the local edge network associated with the I-UPF 103 and / or the local PSA 104. In some embodiments, the NAT 113 co-located with the local PAS can further change the source IP address of the DNS query request to an address specific to the local edge network associated with the local PSA 104. In some other embodiments, the NAT 113 can be omitted. Since the DNS subnet option of the DNS query request has been filled with an IP address or a subnet specific to the local edge network, the central DNS resolver 111 can know which edge network the DNS query request comes from and will use the service server closest to the edge network to respond to the DNS query request. In the embodiment where the NAT 113 is omitted, the DNS forwarder 115 can also change the source IP address of the DNS query request to its own address.

[0108] Figure 7 shows a process 700 for domain name resolution according to an exemplary embodiment. The process 700 can be executed in Figure 6 the network 600 shown. In the process 700, steps that are the same or similar to those in Figure 3 the process 300 and Figure 5 the process 500 shown are represented by the same symbols or similar step numbers, and their repeated descriptions are omitted here.

[0109] At 710, the I-UPF 103 detects a DNS query request from the UE 101 and forwards the DNS query request to the DNS forwarder 115 co-located with the I-UPF 103, where the DNS subnet option of the DNS query request is filled with an IP address or a subnet specific to the local edge network. Optionally, the DNS forwarder 115 can also change the source IP address of the DNS query request to its own address.

[0110] At 712, the DNS query request is forwarded from the DNS forwarder 15 to the central DNS resolver 111 via the local PSA 104.

[0111] At 714, optionally, the source IP address of the DNS query request can be changed by the NAT 113 co-located with the local PSA 104 to an address specific to the local edge network.

[0112] At 716, the central DNS resolver 111 processes the DNS query request. If the central DNS resolver 111 can act as the authoritative name server for the domain name to be resolved, it will respond to the DNS query request with the IP address of the serving server closest to the UE 101, because it knows the location of the UE 101 at least from the subnet option of the DNS query request. On the other hand, if the central DNS resolver 111 cannot resolve the domain name to be resolved included in the DNS query request, it will forward the DNS query request to a higher-level DNS server, such as the authoritative DNS server 112.

[0113] Figure 8 A block diagram of a network device 800 according to an exemplary embodiment is shown. For example, the network device 800 can be implemented as Figure 1 , 2 , 4, and 6 of the SMF 106 or at least a part thereof.

[0114] As Figure 8 shown, the network device 800 can include at least one processor 810 and at least one memory 820, and the memory 820 includes computer program code 830 stored thereon. The at least one memory 820 and the computer program code 830 can be configured to cause the network device 800 to at least perform steps related to the SMF 106 in the example processes 300, 500, 700 described above with reference to Figure 3 , 5 , 7. In addition, the network device 800 can include one or more network interfaces 840, and the network device 800 can receive / send communications from / to other network elements through these network interfaces 840, and these other network elements are, for example but not limited to, the AMF 107 and the UPF 103, 104, and 105.

[0115] Figure 9 A block diagram of a device 900 according to an exemplary embodiment is shown. The device 900 can be implemented in the Figure 8 shown network device 800. The device 900 can be configured to perform steps related to the SMF 106 in the example processes 300, 500, 700 described above with reference to Figure 3 , 5 and 7, but not limited thereto.

[0116] As Figure 9 shown, example device 900 may include a first device 910 configured to perform step 304 in example processes 300, 500, 700 and a second device 920 configured to perform step 306 in example processes 300, 500, 700.

[0117] In some example embodiments, example device 900 may optionally include a third device 930 configured to perform step 302 in example processes 300, 500, 700.

[0118] In some example embodiments, example device 900 may optionally include a fourth device 940 configured to perform the step of sending an IPv6 Router Advertisement (RA) message to UE 101 in example programs 300, 500, 700 ( Figure 3 、 5 not shown in FIGS. 4 and 6).

[0119] Figure 10 FIG. 4 shows a block diagram of a network device 1000 according to an exemplary embodiment. For example, network device 1000 may be implemented as Figure 1 、 2 、an I-UPF of FIGS. 4 and 6 or at least a part thereof.

[0120] As Figure 10 shown, network device 1000 may include at least one processor 1010 and at least one memory 1020, the memory 1020 including computer program code 1030 stored thereon. The at least one memory 1020 and the computer program code 1030 may be configured to cause network device 1000 to perform, using at least one processor 1010, at least steps related to I-UPF 103 in example processes 300, 500 as described above with reference to Figure 3 、 5 、7. Additionally, network device 1000 may include one or more network interfaces 1040 through which network device 1000 may receive / send communications from / to other network elements such as but not limited to SMF 106 and UPFs 104 and 105.

[0121] Figure 11 FIG. 6 shows a block diagram of a device 1100 according to an exemplary embodiment. Device 1100 may be implemented in network device 1000 as shown in Figure 10 FIG. 6. Device 1100 may be configured to perform steps related to I-UPF 103 in example processes 300, 500, 700 as described above with reference to Figure 3 、 5 and 7, but is not limited thereto.

[0122] As Figure 11 shown, example device 1100 may include a first device 1110 and a second device 1120. The first device 1110 is configured to perform step 306 of receiving PFCP configuration from SMF 106 in example processes 300, 500, and 700, and the second device 1120 is configured to perform step 310 of detecting and forwarding DNS query requests in example processes 300, 500, and 700.

[0123] At least one of the processors 810, 1010 discussed above can be of any suitable type applicable to the local technical network and may include one or more of the following: general-purpose processors, dedicated processors, microprocessors, digital signal processors (DSPs), one or more processors in a multi-core processor architecture based on processors, and dedicated processors developed based on, for example, field programmable gate arrays (FPGAs) and application specific integrated circuits (ASICs). At least one of the processors 810, 1010 can be configured to control other elements of the device, such as memory and network interfaces, and cooperate with them to implement the methods described above.

[0124] At least one of the memories 820, 1020 may include at least one storage medium in various forms, such as volatile memory and / or non-volatile memory. Volatile memory may include, but is not limited to, for example, random access memory (RAM) or cache. Non-volatile memory may include, but is not limited to, for example, read-only memory (ROM), hard disk, flash memory, etc. Additionally, at least one of the memories 820, 1020 may include, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or equipment or any combination of the above.

[0125] Furthermore, in various example embodiments, example network devices 800, 1000 may also include at least one other circuit, element, and interface. The circuits, components, elements, and interfaces in example network devices 800, 1000, including at least one of the processors 810, 1010 and at least one of the memories 820, 1020, can be coupled together in any suitable manner, such as electrically, magnetically, optically, electromagnetically, etc., via any suitable connection including, but not limited to, buses, cross switches, wiring, and / or wireless lines.

[0126] Another example embodiment may relate to computer program code or instructions that can cause a device to at least perform the corresponding methods described above.

[0127] Another example embodiment may relate to a computer program product or a computer-readable medium on which such computer program code or instructions are stored. In various example embodiments, such a computer-readable medium may include at least one storage medium in various forms, such as volatile memory and / or non-volatile memory. Volatile memory may include, but is not limited to, for example, RAM, cache, etc. Non-volatile memory may include, but is not limited to, ROM, hard disk, flash memory, etc.

[0128] Unless the context clearly requires otherwise, throughout the specification and claims, the words "comprise", "comprising", etc. will be interpreted in an inclusive sense, rather than an exclusive or exhaustive sense; that is, in the sense of "including, but not limited to". Additionally, when used in this disclosure, the words "herein", "above", "below", and words of similar import shall refer to the entire disclosure, rather than to any particular part of the disclosure. Where the context permits, words used in the singular or plural may also respectively include the plural or singular. The word "or" refers to a list of two or more items, and this word encompasses all of the following interpretations of the word: any item in the list, all items in the list, and any combination of items in the list.

[0129] Furthermore, conditional language used herein, such as "may", "can", "capably", "possibly", "e.g.", "for example", "such as", etc., unless specifically stated otherwise or otherwise understood in the context in which it is used, generally intends to convey that certain embodiments include, while other embodiments do not include certain features, elements, and / or states. Thus, such conditional language is not generally intended to imply that the features, elements, and / or states are in any way required for one or more embodiments, or that one or more embodiments necessarily include logic for determining whether these features, elements, and / or states are included or will be performed in any particular embodiment, with or without author input or prompting.

[0130] Based on the above description, it is obvious that the example embodiments of the present disclosure provide various network functions such as wireless networks, devices for implementing such functions, methods for controlling and / or operating such devices, and computer programs for controlling and / or operating them, as well as media carrying such computer programs.

[0131] As a non-limiting example, an implementation of any of the above boxes, devices, systems, technologies, or methods includes an implementation as hardware, software, firmware, dedicated circuitry or logic, general-purpose hardware or a controller, or other computing devices, or some combination thereof.

[0132] Although the subject matter has been described in language specific to structural features and / or methodological acts, it is to be understood that the subject matter defined in the appended claims is not limited to the specific features or acts described above. On the contrary, the above specific features and acts are disclosed as examples for implementing the claims.

Claims

1. A method for parsing a domain name, comprising: When detecting a change in the data network access identifier (DNAI) of a user equipment (UE), inserting an intermediate user plane function (I-UPF) into a data path of a packet data unit (PDU) session of the UE; and Configuring the I-UPF to forward a Domain Name System (DNS) query request from the UE to a DNS resolver along a path to a local packet data unit session anchor (PSA); Wherein, configuring the I-UPF includes the session management function (SMF) configuring the I-UPF with: A packet detection rule (PDR) that uses the following options to detect packets from the UE: a) a destination IP address that matches the IP address of a DNS server previously communicated to the UE, b) a source IP prefix that matches a first prefix associated with the local PSA, and c) a second prefix dedicated to DNS query requests; and A forwarding action rule (FAR) that forwards the detected packet to the DNS resolver along a path to the local PSA; Wherein, the DNS resolver is a local DNS resolver serving the local PSA, and the local DNS resolver is configured to: Respond to the DNS query request in the case where the local DNS resolver serves as the authoritative DNS server for the domain name included in the DNS query request; Otherwise, after filling the DNS subnet option of the DNS query request with an IP address or subnet specific to the edge network associated with the local PSA, forward the DNS query request to a higher-level DNS server; Wherein, before routing the DNS query request to the DNS resolver, the source IP address of the DNS query request is changed by a network address translator (NAT) co-located with the local PSA to an address specific to the edge network associated with the local PSA.

2. The method according to claim 1, further comprising sending a router advertisement (RA) message to the UE, the RA message including: a) a first prefix associated with the local PSA and a DNS server configuration option associated with the first prefix, the DNS server configuration option including the DNS resolver address, or b) a second prefix dedicated to DNS query requests and a routing information option (RIO) associated with the second prefix, the RIO including a route to the DNS resolver.

3. The method according to claim 1, further comprising: Maintaining, at a session management function (SMF), the address of the DNS server communicated to the UE during the life cycle of the PDU session of the UE.

4. A network device, comprising: At least one processor; And At least one memory including computer program code, the at least one memory and the computer program code being configured to, using the at least one processor, cause the network device to at least perform the following steps: When a change in the data network access identifier (DNAI) of a user equipment (UE) is detected, an intermediate user plane function (I-UPF) is inserted into the data path of a packet data unit (PDU) session of the UE; and Configure the I-UPF to forward a Domain Name System (DNS) query request from the UE to a DNS resolver along a path to a local packet data unit session anchor (PSA); wherein configuring the I-UPF includes configuring the I-UPF by a session management function (SMF) with: A packet detection rule (PDR) that uses the following options to detect packets from the UE: a) a destination IP address that matches the IP address of a DNS server previously communicated to the UE, b) a source IP prefix that matches a first prefix associated with the local PSA, and c) a second prefix dedicated to DNS query requests; and A forwarding action rule (FAR) that forwards the detected packets to the DNS resolver along a path to the local PSA; wherein the DNS resolver is a local DNS resolver serving the local PSA, and the local DNS resolver is configured to: Respond to the DNS query request in the case where the local DNS resolver serves as the authoritative DNS server for the domain name included in the DNS query request; Otherwise, after populating a DNS subnet option of the DNS query request with an IP address or subnet specific to an edge network associated with the local PSA, forward the DNS query request to a higher-level DNS server; wherein, before routing the DNS query request to the DNS resolver, the source IP address of the DNS query request is changed by a network address translator (NAT) co-located with the local PSA to an address specific to an edge network associated with the local PSA.

5. The network device according to claim 4, wherein The at least one memory and the computer program code are further configured to use the at least one processor to cause the network device to at least perform the following steps: Send a Router Advertisement (RA) message to the UE, the RA message including: a) A first prefix associated with the local PSA and a DNS server configuration option associated with the first prefix, the DNS server configuration option including the address of the DNS resolver, or b) A second prefix dedicated to DNS query requests and a Routing Information Option (RIO) associated with the second prefix, the RIO including a route to the DNS resolver.

6. The network device according to claim 4, wherein, The at least one memory and the computer program code are further configured to use the at least one processor to cause the network device to at least perform the following steps: Maintain, at a session management function (SMF), the address of the DNS server communicated to the UE during the lifetime of the PDU session of the UE.

7. A communication device, comprising: Apparatus for inserting an Intermediate User Plane Function (I-UPF) in a data path of a Packet Data Unit (PDU) session of a User Equipment (UE) when a Data Network Access Identifier (DNAI) of the UE changes; And Apparatus for configuring the I-UPF to forward a Domain Name System (DNS) query request from the UE to a DNS resolver along a path to a local Packet Data Unit Session Anchor (PSA); Wherein, the apparatus for configuring the I-UPF includes apparatus for configuring the I-UPF by a Session Management Function (SMF) with: A Packet Detection Rule (PDR) that uses the following options to detect packets from the UE: a) a destination IP address that matches the IP address of a DNS server previously communicated to the UE, b) a source IP prefix that matches a first prefix associated with the local PSA, and c) a second prefix dedicated to DNS query requests; and A Forwarding Action Rule (FAR) that forwards the detected packets to the DNS resolver along a path to the local PSA; Wherein, the DNS resolver is a local DNS resolver serving the local PSA, and the local DNS resolver is configured to: Respond to the DNS query request in the case where the local DNS resolver serves as the authoritative DNS server for the domain name included in the DNS query request; Otherwise, after filling the DNS subnet option of the DNS query request with an IP address or subnet specific to the edge network associated with the local PSA, forward the DNS query request to a higher-level DNS server; Wherein, before routing the DNS query request to the DNS resolver, the source IP address of the DNS query request is changed by a Network Address Translator (NAT) co-located with the local PSA to an address specific to the edge network associated with the local PSA.

8. The apparatus according to claim 7, further comprising apparatus for sending a Router Advertisement (RA) message to the UE, the RA message including: a) a first prefix associated with the local PSA and a DNS server configuration option associated with the first prefix, the DNS server configuration option including the address of the DNS resolver, or b) a second prefix dedicated to DNS query requests and a Route Information Option (RIO) associated with the second prefix, the RIO including a route to the DNS resolver.

9. The apparatus according to claim 7, further comprising: Apparatus for maintaining, at a Session Management Function (SMF), the address of the DNS server communicated to the UE during the lifetime of the PDU session of the UE.

10. A method for resolving a domain name, comprising: Receiving a Packet Forwarding Control Protocol (PFCP) configuration from a Session Management Function (SMF); And Forward a Domain Name System (DNS) query request from a User Equipment (UE) to a DNS resolver along a path to a local Packet Data Unit Session Anchor (PSA) according to the PFCP configuration; wherein, the PFCP configuration includes: a Packet Detection Rule (PDR) for detecting packets from the UE using the following options: a) a destination IP address matching the IP address of the DNS server previously communicated to the UE, b) a source IP prefix matching a first prefix associated with the local PSA, and c) a second prefix dedicated to DNS query requests; and a Forwarding Action Rule (FAR) corresponding to the following forwarding actions: a) forwarding the packet to the local PSA associated with a specific local network, b) forwarding the packet to the local PSA co-located with a Network Address Translator (NAT) having a local network specific address pool, c) forwarding the packet to be processed by a DNS forwarder resolver co-located at the I-UPF or the local PSA; wherein, the DNS resolver is a local DNS resolver serving the local PSA, and the local DNS resolver is configured to: respond to the DNS query request when the local DNS resolver serves as the authoritative DNS server for the domain name included in the DNS query request; otherwise, after filling the DNS subnet option of the DNS query request with an IP address or subnet specific to the edge network associated with the local PSA, forward the DNS query request to a higher-level DNS server; wherein, before routing the DNS query request to the DNS resolver, the source IP address of the DNS query request is changed by a Network Address Translator (NAT) co-located with the local PSA to an address specific to the edge network associated with the local PSA.

11. The method according to claim 10, wherein, The DNS resolver is configured to: respond to the DNS query request when the DNS resolver serves as the authoritative DNS server for the domain name included in the DNS query request; or otherwise, after filling the DNS subnet option of the DNS query request with the full or truncated source IP address of the DNS query request, forward the DNS query request to a higher-level DNS server.

12. The method according to claim 10, wherein Before routing the DNS query request to the DNS resolver, the DNS subnet option of the DNS query request is filled by a DNS forwarder co-located with the I-UPF and / or the local PSA with an IP address or subnet specific to the edge network associated with the local PSA.

13. The method according to claim 10, wherein, Before routing the DNS query request to the DNS resolver, the DNS subnet option of the DNS query request is resolved by a DNS forwarder resolver co-located with the I-UPF and / or the local PSA with an IP address or subnet specific to the edge network associated with the local PSA, and / or the source IP address of the DNS query request is changed by the DNS forwarder resolver to the address of the DNS forwarder resolver.

14. The method according to claim 12 or 13, wherein The DNS resolver is configured to: In the case where the DNS resolver serves as the authoritative DNS server for the domain name included in the DNS query request, respond to the DNS query request; Or Otherwise, forward the DNS query request to a higher-level DNS server.

15. A network device, comprising: At least one processor; And At least one memory, which includes computer program code, and the at least one memory and the computer program code are configured to cause the network device to perform at least the following steps using the at least one processor: Receive a Packet Forwarding Control Protocol (PFCP) configuration from a Session Management Function (SMF); And Forward a Domain Name System (DNS) query request from a User Equipment (UE) to a DNS resolver along a path to a local Packet Data Unit Session Anchor (PSA) according to the PFCP configuration; Wherein, the PFCP configuration includes: A Packet Detection Rule (PDR) for detecting packets from the UE using the following options: a) a destination IP address matching the IP address of the DNS server previously communicated to the UE, b) a source IP prefix matching a first prefix associated with the local PSA, and c) a second prefix dedicated to the DNS query request; and A Forwarding Action Rule (FAR) corresponding to the following multiple forwarding actions: a) forwarding the packet to the local PSA associated with a specific local network, b) forwarding the packet to the local PSA co-located with a Network Address Translator (NAT) having a local network specific address pool, c) forwarding the packet to be processed by a DNS forwarder resolver co-located at the I-UPF or the local PSA; Wherein, the DNS resolver is a local DNS resolver serving the local PSA, and the local DNS resolver is configured to: In the case where the local DNS resolver serves as the authoritative DNS server for the domain name included in the DNS query request, respond to the DNS query request; Otherwise, after filling the DNS subnet option of the DNS query request with an IP address or subnet specific to the edge network associated with the local PSA, forward the DNS query request to a higher-level DNS server; Wherein, before routing the DNS query request to the DNS resolver, the source IP address of the DNS query request is changed by a Network Address Translator (NAT) co-located with the local PSA to an address specific to the edge network associated with the local PSA.

16. The network device according to claim 15, wherein, The DNS resolver is configured to: In the case where the DNS resolver serves as the authoritative DNS server for the domain name included in the DNS query request, respond to the DNS query request; Or Otherwise, after filling the DNS subnet option of the DNS query request with the complete or truncated source IP address of the DNS query request, forward the DNS query request to a higher-level DNS server.

17. The network device according to claim 15, wherein, Before routing the DNS query request to the DNS resolver, the DNS subnet option of the DNS query request is filled by a DNS forwarder co-located with the I-UPF and / or the local PSA with an IP address or subnet specific to the edge network associated with the local PSA.

18. The network device according to claim 15, wherein, Before routing the DNS query request to the DNS resolver, the DNS subnet option of the DNS query request is filled by a DNS forwarder resolver co-located with the I-UPF and / or the local PSA with an IP address or subnet specific to the edge network associated with the local PSA, and / or the source IP address of the DNS query request is changed by the DNS forwarder resolver to the address of the DNS forwarder resolver.

19. The network device according to claim 17 or 18, wherein, The DNS resolver is configured to: In the case where the DNS resolver serves as the authoritative DNS server for the domain name included in the DNS query request, respond to the DNS query request; or Otherwise, forward the DNS query request to a higher-level DNS server.

20. A communication device, comprising: Means for receiving a Packet Forwarding Control Protocol (PFCP) configuration from a Session Management Function (SMF); And Means for forwarding a Domain Name System (DNS) query request from a User Equipment (UE) to a DNS resolver along a path to a local Packet Data Unit Session Anchor (PSA) according to the PFCP configuration; Wherein, the PFCP configuration includes: A Packet Detection Rule (PDR) for detecting packets from the UE using the following options: a) a destination IP address matching the IP address of a DNS server previously communicated to the UE, b) a source IP prefix matching a first prefix associated with the local PSA, and c) a second prefix dedicated to DNS query requests; and A Forwarding Action Rule (FAR) corresponding to the following multiple forwarding actions: a) forwarding the packet to the local PSA associated with a specific local network, b) forwarding the packet to the local PSA co-located with a Network Address Translator (NAT) having a local network specific address pool, c) forwarding the packet to be processed by a DNS forwarder resolver co-located at the I-UPF or the local PSA; Wherein, the DNS resolver is a local DNS resolver serving the local PSA, and the local DNS resolver is configured to: In the case where the local DNS resolver serves as the authoritative DNS server for the domain name included in the DNS query request, respond to the DNS query request; Otherwise, after populating the DNS subnet option of the DNS query request with an IP address or subnet specific to the edge network associated with the local PSA, forward the DNS query request to a higher-level DNS server; wherein, before routing the DNS query request to the DNS resolver, the source IP address of the DNS query request is changed by a network address translator (NAT) co-located with the local PSA to an address specific to the edge network associated with the local PSA.

21. The apparatus according to claim 20, wherein, The DNS resolver is configured to: respond to the DNS query request when the DNS resolver serves as the authoritative DNS server for the domain name included in the DNS query request; or otherwise, after populating the DNS subnet option of the DNS query request with the full or truncated source IP address of the DNS query request, forward the DNS query request to a higher-level DNS server.

22. The device according to claim 20, wherein, Before routing the DNS query request to the DNS resolver, the DNS subnet option of the DNS query request is populated by a DNS forwarder co-located with the I-UPF and / or the local PSA with an IP address or subnet specific to the edge network associated with the local PSA.

23. The apparatus according to claim 20, wherein Before routing the DNS query request to the DNS resolver, the DNS subnet option of the DNS query request is populated by a DNS forwarder resolver co-located with the I-UPF and / or the local PSA with an IP address or subnet specific to the edge network associated with the local PSA, and / or the source IP address of the DNS query request is changed by the DNS forwarder resolver to the address of the DNS forwarder resolver.

24. The device according to claim 22 or 23, wherein, The DNS resolver is configured to: respond to the DNS query request when the DNS resolver serves as the authoritative DNS server for the domain name included in the DNS query request; or otherwise, forward the DNS query request to a higher-level DNS server.

25. A computer-readable medium having instructions stored thereon, which when executed by at least one processor of a device cause the device to perform the method according to any one of claims 1-3.

26. A computer-readable medium having instructions stored thereon, which when executed by at least one processor of a device cause the device to perform the method according to any one of claims 10-14.

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