WO2021138804A1 - Method and apparatus for resolving domain name in case of local access to data network - Google Patents

Method and apparatus for resolving domain name in case of local access to data network Download PDF

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Publication number
WO2021138804A1
WO2021138804A1 PCT/CN2020/070686 CN2020070686W WO2021138804A1 WO 2021138804 A1 WO2021138804 A1 WO 2021138804A1 CN 2020070686 W CN2020070686 W CN 2020070686W WO 2021138804 A1 WO2021138804 A1 WO 2021138804A1
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WIPO (PCT)
Prior art keywords
dns
query request
local
resolver
address
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PCT/CN2020/070686
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English (en)
French (fr)
Inventor
Markus ISOMÄKI
Pekka Korja
Laurent Thiebaut
Yang Shen
Omar Elloumi
Original Assignee
Nokia Shanghai Bell Co., Ltd.
Nokia Solutions And Networks Oy
Nokia Technologies Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by Nokia Shanghai Bell Co., Ltd., Nokia Solutions And Networks Oy, Nokia Technologies Oy filed Critical Nokia Shanghai Bell Co., Ltd.
Priority to PCT/CN2020/070686 priority Critical patent/WO2021138804A1/en
Priority to CN202080092474.7A priority patent/CN114946214A/zh
Publication of WO2021138804A1 publication Critical patent/WO2021138804A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L61/00—Network arrangements, protocols or services for addressing or naming
    • H04L61/09—Mapping addresses
    • H04L61/25—Mapping addresses of the same type
    • H04L61/2503—Translation of Internet protocol [IP] addresses
    • H04L61/2514—Translation of Internet protocol [IP] addresses between local and global IP addresses
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L61/00—Network arrangements, protocols or services for addressing or naming
    • H04L61/45—Network directories; Name-to-address mapping
    • H04L61/4505—Network directories; Name-to-address mapping using standardised directories; using standardised directory access protocols
    • H04L61/4511—Network directories; Name-to-address mapping using standardised directories; using standardised directory access protocols using domain name system [DNS]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L2101/00—Indexing scheme associated with group H04L61/00
    • H04L2101/60—Types of network addresses
    • H04L2101/668—Internet protocol [IP] address subnets

Definitions

  • Various exemplary embodiments generally relate to communication technologies, and more particularly, to methods and apparatuses for resolving domain names in case of local access to a data network (DN) .
  • DN data network
  • Edge computing is supported in the 5G Core Network (5GC) to enable operators and 3rd party services to be hosted close to the user equipment's (UE's) access point of attachment so as to achieve an efficient service delivery through the reduced end-to-end latency and load on the transport network.
  • a User Plane Function (UPF) close to the UE may be selected to route the user traffic to a local Data Network (DN)
  • DN local Data Network
  • the 5GC may select the traffic to be routed to the applications in the local DN.
  • PDU packet data unit
  • PSAs PDU session anchors
  • exemplary embodiments provide a method for resolving a domain name.
  • the method may comprise, upon detection of Data Network Access Identifier (DNAI) change for 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.
  • the method may further comprise 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) .
  • DNS Domain Name System
  • the step of configuring the I-UPF may comprise configuring, by a Session Management Function (SMF) , the I-UPF with a packet detection rule (PDR) and a forwarding action rule (FAR) .
  • the packet detection rule (PDR) may be applied to detect packets from the UE with one of: 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 DNS query requests.
  • the forwarding action rule (FAR) may be applied to forward the detected packets to the DNS resolver along the path to the local PSA.
  • the method may further comprise sending a Router Advertisement (RA) message to the UE.
  • the RA message may comprise a) the 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 the DNS resolver, or b) the 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.
  • RA Router Advertisement
  • the RA message may comprise a) the 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 the DNS resolver, or b) the 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.
  • RIO Route Information Option
  • the method may further comprise maintaining at a Session Management Function (SMF) an address of the DNS server communicated to the UE during lifetime of the PDU session of the UE.
  • SMF Session Management Function
  • exemplary embodiments provide 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 may be configured to, with the at least one processor, cause the network device at least to perform following steps: upon detection of Data Network Access Identifier (DNAI) change for 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 to a DNS resolver along a path to a local packet data unit session anchor (PSA) .
  • DAS Domain Name System
  • the step of configuring the I-UPF may comprise 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 applied to detect packets from the UE with one of: 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 DNS query requests.
  • the FAR may be applied to forward the detected packets to the DNS resolver along the path to the local PSA.
  • the at least one memory and the computer program code may be further configured to, with the at least one processor, cause the network device at least to perform a following step: sending a Router Advertisement (RA) message to the UE.
  • the RA message may comprise a) the 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 the DNS resolver, or b) the 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.
  • RA Router Advertisement
  • the at least one memory and the computer program code may be further configured to, with the at least one processor, cause the network device at least to perform a following step: maintaining at a Session Management Function (SMF) an address of the DNS server communicated to the UE during lifetime of the PDU session of the UE.
  • SMF Session Management Function
  • exemplary embodiments provide a communication apparatus.
  • the communication apparatus may comprise 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) upon detection of Data Network Access Identifier (DNAI) change for the UE, and means 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) .
  • I-UPF intermediate User Plane Function
  • PDU packet data unit
  • UE user equipment
  • DNS Domain Name System
  • means for configuring the I-UPF comprises means for 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 applied to detect packets from the UE with one of: 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 DNS query requests.
  • the FAR may be applied to forward the detected packets to the DNS resolver along the path to the local PSA.
  • the apparatus may further comprise means for sending a Router Advertisement (RA) message to the UE.
  • the RA message may comprise a) the 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 the DNS resolver, or b) the 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.
  • RA Router Advertisement
  • the RA message may comprise a) the 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 the DNS resolver, or b) the 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.
  • RIO Route Information Option
  • the apparatus may further comprise means for maintaining at a Session Management Function (SMF) an address of the DNS server communicated to the UE during lifetime of the PDU session of the UE.
  • SMF Session Management Function
  • exemplary embodiments provide a method for resolving a domain name comprising receiving Packet Forwarding Control Protocol (PFCP) configuration from a Session Management Function (SMF) , and 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.
  • PFCP Packet Forwarding Control Protocol
  • SMF Session Management Function
  • DNS Domain Name System
  • the PFCP configuration comprises: a packet detection rule (PDR) for detecting packets from the UE with one or more of following options: 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 DNS query requests; and a forwarding action rule (FAR) that corresponds to one or more of 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) with 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.
  • PDR packet detection rule
  • FAR forwarding action rule
  • the DNS resolver is a local DNS resolver serving the local PSA.
  • the local DNS resolver is configured to: respond to the DNS query request in the case where the local DNS resolver acts as an 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 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.
  • 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.
  • NAT Network Address Translator
  • the DNS resolver is configured to: respond to the DNS query request in the case where the DNS resolver acts as an 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 after populating a DNS subnet option of the DNS query request with the full or truncated source IP address of the DNS query request.
  • a 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 an edge network associated with the local PSA.
  • a 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 an 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 an address of the DNS forwarder resolver.
  • the DNS resolver is configured to: respond to the DNS query request in the case where the DNS resolver acts as an 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.
  • exemplary embodiments provide 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 configured to, with the at least one processor, cause the network device at least to perform following steps: receiving Packet Forwarding Control Protocol (PFCP) configuration from a Session Management Function (SMF) ; and 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.
  • PFCP Packet Forwarding Control Protocol
  • SMF Session Management Function
  • DNS Domain Name System
  • the PFCP configuration comprises: a packet detection rule (PDR) for detecting packets from the UE with one or more of following options: 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 DNS query requests; and a forwarding action rule (FAR) that corresponds to one or more of 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) with 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.
  • PDR packet detection rule
  • FAR forwarding action rule
  • the DNS resolver is a local DNS resolver serving the local PSA.
  • the local DNS resolver is configured to: respond to the DNS query request in the case where the local DNS resolver acts as an 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 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.
  • 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.
  • NAT Network Address Translator
  • the DNS resolver is configured to: respond to the DNS query request in the case where the DNS resolver acts as an 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 after populating a DNS subnet option of the DNS query request with the full or truncated source IP address of the DNS query request.
  • a 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 an edge network associated with the local PSA.
  • a 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 an 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 an address of the DNS forwarder resolver.
  • the DNS resolver is configured to: respond to the DNS query request in the case where the DNS resolver acts as an 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.
  • exemplary embodiments provide an communication apparatus comprising: means for receiving 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.
  • PFCP Packet Forwarding Control Protocol
  • SMF Session Management Function
  • DNS Domain Name System
  • the PFCP configuration comprises: a packet detection rule (PDR) for detecting packets from the UE with one or more of following options: 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 DNS query requests; and a forwarding action rule (FAR) that corresponds to one or more of 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) with 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.
  • PDR packet detection rule
  • FAR forwarding action rule
  • the DNS resolver is a local DNS resolver serving the local PSA.
  • the local DNS resolver is configured to: respond to the DNS query request in the case where the local DNS resolver acts as an 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 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.
  • 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.
  • NAT Network Address Translator
  • the DNS resolver is configured to: respond to the DNS query request in the case where the DNS resolver acts as an 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 after populating a DNS subnet option of the DNS query request with the full or truncated source IP address of the DNS query request.
  • a 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 an edge network associated with the local PSA.
  • a 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 an 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 an address of the DNS forwarder resolver.
  • the DNS resolver is configured to: respond to the DNS query request in the case where the DNS resolver acts as an 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.
  • exemplary embodiments provide a computer readable medium having instructions stored thereon, the instructions, when executed by at least one processor of an apparatus, causing the apparatus to perform any one of the above methods.
  • Fig. 1 illustrates a schematic architecture diagram of a 5G system with an Edge Application Server (EAS) hosted in a data network;
  • EAS Edge Application Server
  • Fig. 2 illustrates a schematic block diagram of a network in accordance with an exemplary embodiment.
  • Fig. 3 illustrates a procedure of domain name resolution in accordance with an exemplary embodiment.
  • Fig. 4 illustrates a schematic block diagram of a network in accordance with an exemplary embodiment.
  • Fig. 5 illustrates a procedure of domain name resolution in accordance with an exemplary embodiment.
  • Fig. 6 illustrates a schematic block diagram of a network in accordance with an exemplary embodiment.
  • Fig. 7 illustrates a procedure of domain name resolution in accordance with an exemplary embodiment.
  • Fig. 8 illustrates a block diagram of a network device in accordance with an exemplary embodiment.
  • Fig. 9 illustrates a block diagram of a communication apparatus in accordance with an exemplary embodiment.
  • Fig. 10 illustrates a block diagram of a network device in accordance with an exemplary embodiment.
  • Fig. 11 illustrates a block diagram of a communication apparatus in accordance with an exemplary embodiment.
  • Fig. 1 schematically shows a 5G system 100.
  • exemplary embodiments discussed below may be implemented in or with the 5G system 100.
  • a user equipment (UE) 101 is connected to a 5G network at an access node (AN) 102, for example a base station gNB, and then to a data network (DN) 108 through the 5G network.
  • the DN 108 may be for example internet, in which a plurality of edge application servers (EASs) 109 may be deployed.
  • EASs edge application servers
  • the UE 101 is connected to User Plane Functions (UPFs) including an intermediate UPF (I-UPF) 103, a local UPF (L-UPF) 104 and a central UPF (C-UPF) 105.
  • UPFs User Plane Functions
  • the 5G system separates user plane functions from control plane functions in order for flexible and customizable deployment of the UPFs.
  • the central UPF 105 may be deployed at a centralized location, and the local UPF 104 may be deployed at a distributed location close to the UE 101, each of which provides an access to the DN 108 through a N6 interface (also referred to as "reference point" or “reference interface” ) .
  • Packet Data Unit (PDU) exchange between the UE 101 and the DN 108 identified by a Data Network Name (DNN) is supported by a PDU session established therebetween.
  • the PDU session of the UE 101 may simultaneously correspond to two N6 interfaces to the DN 108, and the UPFs 104, 105 that terminate the N6 interfaces are called as a PDU session anchor (PSA) or PSA UPF.
  • PSA PDU session anchor
  • the I-UPF 103 is inserted before and connected via a N9 interface to the local UPF 104 and the central UPF105.
  • the I-UPF 103 may act as an Uplink Classifier (ULCL) or a Branching Point (BP) so as 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 may also act as and/or co-located with the local PSA 104.
  • the I-UPF 103 is connected with the AN 102 via a N3 interface.
  • a Session Management Function (SMF) 106 may manage the PDU session of the UE 101 by controlling the UPFs 103, 104 and 105.
  • the SMF 106 may interact with the UPFs 103, 104 and 105 over a N4 interface. For example, the SMF 106 may select the L-UPF 104 for PDU session establishment or relocation through a N4 Session Establishment procedure.
  • the SMF 106 may also decide to insert in the data path of the PDU session of the UE 101 the UPF 103 supporting ULCL or BP functionality during or after the PDU session establishment, or to remove from the data path of the PDU session the UPF supporting ULCL or BP functionality after the PDU session establishment.
  • An Access and Mobility Management Function (AMF) 107 is connected to the UE 101, the AN 102 and the SMF 106 via a N1 interface, a N2 interface and a N11 interface, respectively.
  • the AMF 107 may be a network function that handles various connection and mobility management tasks. For example, the AMF 107 may report reachability or a Mobility Event of the UE to the SMF 106.
  • the Edge Application Server (EAS) 109 may be deployed in the DN 108 to serve an application service.
  • the EAS 109 may include a plurality of instances that host same content or service and are deployed in different sites/locations.
  • DNS Domain Name System
  • the UE's IP address does not reveal anything about its location.
  • the UE's 101 IP address (or IPv6 prefix) is only associated with the central PSA 105. Even if the UE 101 is at a location where it has a local access to the DN 108 through the local PSA 104, a central DNS resolver (not shown) behind the central PSA 105 knows nothing about the UE's current location. Thus, the authoritative DNS server also fails to get information about the UE's location or the location of the local PSA/the edge network the UE is connected to and cannot provide translation from a fully qualified domain name (FQDN) of a service towards an EAS located near to the UE.
  • FQDN fully qualified domain name
  • exemplary embodiments described herein provide mechanisms for DNS resolution which takes into consideration of UE's location information.
  • Exemplary embodiments may ensure accurate mapping of a DNS query to an IP address of a service server closest to the UE by taking advantage of UE's location information, thereby improving service latency, traffic routing and user service experience.
  • Fig. 2 shows a schematic block diagram of a network 200 in accordance with an exemplary embodiment.
  • same or similar components are represented with same or similar reference signs or numerals and repetitive description thereof would be omitted. In one or more of the drawings, some components shown in other drawings may be omitted for concision and to avoid redundant description thereof.
  • the UE 101 has a local access to the DN 108 (Fig. 1) through the local PSA 104 and a central access to the DN 108 (Fig. 1) through the central PSA 105.
  • the intermediate UPF 103 functions to selectively route traffic from the UE 101 to the local PSA 104 or the central PSA 105.
  • a local DNS resolver 110 is deployed behind the local PSA 104 to handle DNS query requests from the UE 101 through the local PSA 104.
  • the local DNS resolver 110 is locally deployed with and dedicated to the local PSA 104, and it knows IP address or IP subnet of the local PSA 104 or the edge network where the local PSA 104 is deployed.
  • a central DNS resolver 111 is centrally deployed behind the central PSA 105.
  • the local DNS resolver 110 and the central DNS 111 may act for example as a full recursive resolver, and they both are connected to a higher level DNS resolver, for example to an authoritative DNS server 112.
  • the local DNS resolver 110 may be connected to the central DNS resolver 111.
  • Fig. 3 shows a procedure 300 of domain name resolution in accordance with an exemplary embodiment.
  • the procedure 300 may be performed in the network 200 shown in Fig. 2.
  • the SMF 106 maintains information of DNS server IP address communicated to the UE 101.
  • the DNS server IP address may be communicated to the UE 101 by NAS signaling or DHCP based methods.
  • the SMF 106 may store the DNS server IP address communicated to the UE 101 during the lifetime of the UE PDU session.
  • the SMF 106 inserts an intermediate UPF 103 in the data path of the PDU session of the UE 101 when a Data Network Access Identifier (DNAI) change is detected for the UE 101.
  • the DNAI is an identifier of a user plane access to the DN 108 where the EAS 109 is deployed, and it may be understood as an access point to the EAS 109 in the DN 108.
  • the 5G network provides a plurality of access point to the same DN 108.
  • the DNAI for the UE 101 may change from a first DNAI to a second DNAI.
  • the UE 106 when the UE 106 initially attaches to the 5G network and obtains a local access associated with a DNAI to the DN 108, it may also be deemed as DNAI change for the UE 101.
  • the SMF 106 may decide to insert the I-UPF 103 when it detects the DNAI change for the UE 101, including DNAI change caused by UE mobility and new DNAI allocation.
  • the SMF 106 may configure the I-UPF103 with Packet Forwarding Control Protocol (PFCP) configuration so that the I-UPF 103 will forward a DNS query request from the UE 101 to the local DNS resolver 110 along a path to the local PSA 104.
  • the PFCP configuration for the I-UPF 103 may include a packet detection rule (PDR) for detecting packets, or in particular DNS query packets, from the UE 101, and a forwarding action rule (FAR) for forwarding the detected packets.
  • PDR packet detection rule
  • FAR forwarding action rule
  • the I-UPF 103 may serve as an Uplink Classifier (ULCL) and the SMF 106 may configure the I-UPF 103 with a PDR to detect packets from the UE 101 with a destination IP address matching an IP address of a DNS server previously communicated to the UE 101.
  • the SMF 106 may maintain information of DNS server IP address communicated to the UE 101 by NAS signaling or DHCP methods.
  • the I-UPF 103 can detect the DNS query request packets by using the PDR configured by the SMF 106.
  • the I-UPF 103 may serve as a Branching Point (BP) and the SMF 106 may configure the I-UPF 103 with a PDR to detect packets from the UE 101 with a particular IPv6 prefix previously communicated to the UE 101.
  • the SMF 106 may send an IPv6 Router Advertisement (RA) message with an IPv6 prefix that is associated with the local PSA 104.
  • the RA message may further include a DNS server configuration option providing a DNS resolver, for example the local DNS resolver 110 with high priority.
  • the UE 101 With the RA message, the UE 101 will send its DNS query requests to the local DNS resolver 110 associated with the local PSA 104, and the I-UPF 103 can detect the DNS query request packets by using the PDR configured by the SMF 106.
  • the RA message may include an IPv6 prefix that is dedicated to DNS query requests, and a Route Information Option (RIO) associated with the IPv6 prefix and thus with the DNS query requests.
  • the RIO may include a route to a DNS resolver, for example the local DNS resolver 110.
  • the UE 101 With the RA message, the UE 101 will send its DNS query requests with the dedicated IPv6 prefix and the route information to the local DNS resolver 110, and the I-UPF 103 can detect the DNS query request packets by using the PDR configured by the SMF 106.
  • the FAR configured by the SMF 106 for the I-UPF 103 specifies how the detected packets would be forwarded.
  • the detected packets would be forwarded to the local DNS resolver 110 along the path to the local PSA 104. It could be implemented by for example anycast, IP tunneling and so on.
  • the destination address of the DNS query request could 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 such a case, a source IP address of return packets would be changed back from the local DNS resolver 110 to the destination address.
  • the FAR may be configured to just 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.
  • the UE 101 will issue a DNS query request with a source IP address and a destination IP address.
  • the source IP address may be the UE's IP address provided by the central PSA 105, or include an IPv6 prefix received from the SMF 106 in the RA message.
  • the destination IP address may be the DNS server provided by NAS signaling or DHCP based methods, for example the central DNS resolver 105, or the local DNS resolver 110 provided in the RA message.
  • the DNS query request may further include the route information for the local DNS resolver 110 provided in the RA message.
  • 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.
  • the I-UPF 103 may detect packets from the UE 101 that has 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 DNS query requests previously sent to the UE 101 in the RA message.
  • the detected pockets would be forwarded by the I-UPF 103 to the local DNS resolver 110 via the local PSA 104.
  • the DNS query request would be handled at the local DNS resolver 110. If the domain name to be resolved included in the DNS query request can be resolved directly by the local DNS resolver 110, or in other words, if the local DNS resolver 110 may act as an authoritative name server for the domain name to be resolved, the local DNS resolver 110 will respond to the DNS query request with an IP address of a service server. As 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 respond to the DNS query request with a service server closest to the UE 101.
  • the local DNS resolver 110 will forward the DNS query request to a higher level DNS server after populating a DNS subnet option of the DNS query request with an IP address or subnet of the local PSA 104 or the local edge network.
  • the DNS subnet option may be populated with a full or truncated IP of the local PSA 104.
  • the truncated IP address may be formed by taking any number of the most significant bits of the IP address while transforming the rest bits of the IP address to zero.
  • the local DNS resolver 110 may 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 to the authoritative DNS server 112 if needed.
  • Fig. 4 shows a network 400 according to an exemplary embodiment.
  • Components in the network 400 same as or similar to those in the above embodiments will be denoted with same or similar numerals and a repetitive description thereof will be omitted.
  • a Network Address Translator (NAT) 113 and a DNS resolver 114 are provided.
  • the NAT 113 may be co-located with the local PSA 104, and it may have a local edge network specific address pool.
  • the DNS resolver 114 will change the IP source address of the DNS query request from the UE's centrally assigned IP address to a local edge network specific address.
  • the DNS resolver 114 can map the DNS query request to the particular local edge network.
  • the DNS resolver 114 can serve a plurality of local edge networks.
  • the DNS resolver 114 does not need to be deployed locally at the edge network associated with the local PSA 104, and it could be a remote DNS (R-DNS) resolver.
  • the DNS resolver 114 may also be deployed locally at the edge network associated with the local PSA 104, but it does not need to operate based on the local context.
  • the remote DNS resolver 114 knows where the DNS query request comes from, i.e., where the UE 101 locates, even without the local context.
  • Fig. 5 shows a procedure 500 of domain name resolution in accordance with an exemplary embodiment.
  • the procedure 500 may be performed in the network 400 shown in Fig. 4.
  • steps same or similar to those in the procedure 300 shown in Fig. 3 are denoted by the same or similar step numbers and a repetitive description thereof would be omitted.
  • the I-UPF 103 detects the 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.
  • the NAT 113 when the DNS query request is routed to the local PSA 104 where the NAT 113 is co-located, the NAT 113 translates the IP source address of the DNS query request from the UE's centrally assigned IP address to the address specific to the local edge network, e.g., the local PSA specific address.
  • the DNS resolver 114 handles the DNS query request. If the DNS resolver 114 can act as an authoritative name server for the domain name to be resolved, it will respond to the DNS query request with an IP address of a service server closest to the UE 101 as 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, it will forward the DNS query request to a higher level DNS server after populating a DNS subnet option of the DNS query request with a full or truncated source IP address of the DNS query request. The DNS resolver 114 may 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 to the authoritative DNS server 112 if needed.
  • Fig. 6 shows a network 600 in accordance with an exemplary embodiment.
  • Components in the network 600 same as or similar to those in the above embodiments will be denoted with same or similar numerals and a repetitive description thereof will be omitted.
  • a DNS forwarder 115 is provided instead of the local DNS resolver 110 or the remote DNS resolver 114.
  • the DNS forwarder 115 may be co-located with the I-UPF 103 and/or the L-PAS 104. As discussed above, the I-UPF 103 and the L-PAS 104 may be co-located with each other.
  • the SMF 106 may configure the I-UPF 103 to forward the DNS query request from the UE 101 to the DNS forwarder 115, the local PSA 104 and then to the central DNS resolver 111.
  • the DNS forwarder 115 is locally deployed with the I-UPF 103 and the local PSA 104, it can operate based on local context.
  • the DNS forwarder 115 may populate a DNS subnet option of the DNS query request with an IP address or subnet specific to the local edge network associated with the I-UPF 103 and/or the local PSA 104.
  • the NAT 113 co-located with the local PAS may 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.
  • the NAT 113 may be omitted.
  • the central DNS resolver 111 can know which edge network the DNS query request comes from and will respond to the DNS query request with a service server closest to the edge network.
  • the DNS forwarder 115 may also change the source IP address of the DNS query request to the address of the DNS forwarder 115 itself.
  • Fig. 7 shows a procedure 700 of domain name resolution in accordance with an exemplary embodiment.
  • the procedure 700 may be performed in the network 600 shown in Fig. 6.
  • steps same or similar to those in the procedure 300 shown in Fig. 3 and the procedure 500 shown in Fig. 5 are denoted by the same or similar step numbers and a repetitive description thereof is omitted here.
  • the I-UPF 103 detects the 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 a DNS subnet option of the DNS query request is populated with an IP address or subnet specific to the local edge network.
  • the DNS forwarder 115 may also change the source IP address of the DNS query request to the address of the DNS forwarder 115 itself.
  • the DNS query request is forwarded from the DNS forwarder 15 to the central DNS resolver 111 via the local PSA 104.
  • the source IP address of the DNS query request may be changed by the NAT 113 co-located with the local PSA 104 to an address specific to the local edge network.
  • the central DNS resolver 111 handles the DNS query request. If the central DNS resolver 111 can act as an authoritative name server for the domain name to be resolved, it will respond to the DNS query request with an IP address of a service server closest to the UE 101 as 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, for example the authoritative DNS server 112.
  • Fig. 8 shows a block diagram of a network device 800 according to an exemplary embodiment.
  • the network device 800 may be implemented as the SMF 106 of Figs. 1, 2, 4 and 6 or at least a part thereof.
  • the network device 800 may include at least one processor 810 and at least one memory 820 that includes computer program code 830 stored thereon.
  • the at least one memory 820 and the computer program code 830 may be configured to, with the at least one processor 810, cause the network device 800 at least to perform steps relating to the SMF 106 in the example procedure 300, 500, 700 described above with reference to Figs. 3, 5, 7.
  • the network device 800 may include one or more network interfaces 840 through which the network device 800 may receive/transmit communications from/to other network elements such as but not limited to the AMF 107 and the UPFs 103, 104 and 105.
  • Fig. 9 shows a block diagram of an apparatus 900 according to an exemplary embodiment.
  • the apparatus 900 may be implemented in the network device 800 shown in Fig. 8.
  • the apparatus 900 may be configured to perform the steps relating to the SMF 106 in the example procedures 300, 500, 700 described above with reference to Figs. 3, 5 and 7 but is not limited thereto.
  • the example apparatus 900 may comprise a first means 910 configured to perform the step 304 in the example procedures 300, 500, 700 and a second means 920 configured to perform the step 306 in the example procedures 300, 500, 700.
  • the example apparatus 900 may optionally comprise a third means 930 configured to perform the step 302 in the example procedures 300, 500, 700.
  • the example apparatus 900 may optionally comprise a fourth means 940 configured to perform the step (not shown in Figs, 3, 5 and 7) of sending the IPv6 Router Advertisement (RA) message to the UE 101 in the example procedures 300, 500, 700.
  • a fourth means 940 configured to perform the step (not shown in Figs, 3, 5 and 7) of sending the IPv6 Router Advertisement (RA) message to the UE 101 in the example procedures 300, 500, 700.
  • Fig. 10 shows a block diagram of a network device 1000 according to an exemplary embodiment.
  • the network device 1000 may be implemented as the I-UPF 103 of Figs. 1, 2, 4 and 6 or at least a part thereof.
  • the network device 1000 may include at least one processor 1010 and at least one memory 1020 that includes computer program code 1030 stored thereon.
  • the at least one memory 1020 and the computer program code 1030 may be configured to, with the at least one processor 1010, cause the network device 1000 at least to perform steps relating to the I-UPF 103 in the example procedure 300, 500, 700 described above with reference to Figs. 3, 5, 7.
  • the network device 1000 may include one or more network interfaces 1040 through which the network device 1000 may receive/transmit communications from/to other network elements such as but not limited to the SMF 106 and the UPFs 104 and 105.
  • Fig. 11 shows a block diagram of an apparatus 1100 according to an exemplary embodiment.
  • the apparatus 1100 may be implemented in the network device 1000 shown in Fig. 10.
  • the apparatus 1100 may be configured to perform the steps relating to the I-UPF 103 in the example procedures 300, 500, 700 described above with reference to Figs. 3, 5 and 7 but is not limited thereto.
  • the example apparatus 1100 may comprise a first means 1110 configured to perform the step 306 of receiving PFCP configuration from the SMF 106 in the example procedures 300, 500, 700 and a second means 1120 configured to perform the step 310 of detecting and forwarding DNS query requests in the example procedures 300, 500, 700.
  • the at least one processor 810, 1010 discussed above may be of any appropriate type that is suitable for the local technical network, and may include one or more of general purpose processors, special purpose processor, microprocessors, a digital signal processor (DSP) , one or more processors in a processor based multi-core processor architecture, as well as dedicated processors such as those developed based on Field Programmable Gate Array (FPGA) and Application Specific Integrated Circuit (ASIC) .
  • the at least one processor 810, 1010 may be configured to control other elements of the devices such as the memory and the network interface and operate in cooperation with them to implement the methods discussed above.
  • the at least one memory 820, 1020 may include at least one storage medium in various forms, such as a volatile memory and/or a non-volatile memory.
  • the volatile memory may include but not limited to for example a random access memory (RAM) or a cache.
  • the non-volatile memory may include but not limited to for example a read only memory (ROM) , a hard disk, a flash memory, and the like.
  • the at least one memory 820, 1020 may include but not limited to an electric, a magnetic, an optical, an electromagnetic, an infrared, or a semiconductor system, apparatus, or device or any combination of the above.
  • the example network device 800, 1000 may also include at least one other circuitry, element, and interface.
  • the circuitries, parts, elements, and interfaces in the example network device 800, 1000, including the at least one processor 810, 1010 and the at least one memory 820, 1020 may be coupled together via any suitable connections including but not limited to buses, crossbars, wiring and/or wireless lines, in any suitable ways, for example electrically, magnetically, optically, electromagnetically, and the like.
  • Another example embodiment may relate to computer program codes or instructions which may cause an apparatus to perform at least respective methods described above.
  • Such a computer readable medium may include at least one storage medium in various forms such as a volatile memory and/or a non-volatile memory.
  • the volatile memory may include but not limited to for example, a RAM, a cache, and so on.
  • the non-volatile memory may include, but not limited to, a ROM, a hard disk, a flash memory, and so on.
  • conditional language used herein such as, among others, “can, ” “could, ” “might, ” “may, ” “e.g., ” “for example, ” “such as” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states.
  • conditional language is not generally intended to imply that 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 deciding, with or without author input or prompting, whether these features, elements and/or states are included or are to be performed in any particular embodiment.
  • example embodiments of the present disclosure provide, for example, various network functions of wireless network, an apparatus embodying the same, a method for controlling and/or operating the same, and computer programs controlling and/or operating the same as well as mediums carrying such computer program
  • Implementations of any of the above described blocks, apparatuses, systems, techniques or methods include, as non-limiting examples, implementations as hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.
PCT/CN2020/070686 2020-01-07 2020-01-07 Method and apparatus for resolving domain name in case of local access to data network WO2021138804A1 (en)

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