Name resolution method ans DNS server for mobile communication system

Abstract

To make it possible to automatically select and provide an IP address of a server capable of minimizing a communication delay time from an access source.SOLUTION: A mobile communication system includes a core network comprising a plurality of sub-networks. A DNS server receives, from a user terminal, an inquiry including a domain name of an inquiry object and identification information on one or more network apparatuses in a sub-network corresponding to an in-zone area of the user terminal of the plurality of sub-networks, where a plurality of server apparatuses correspond to the domain name of the inquiry object, identifies an IP address corresponding to the identification information on the one or more network apparatuses included in the inquiry out of the IP addresses of the plurality of server apparatuses corresponding to the domain name of the inquiry object, and transmits the identified IP address, as an answer to the inquiry, to the user terminal.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a name resolution method, a DNS server, and a user terminal for a mobile communication system. [Background technology]

[0002] Conventionally, a load balancing system using DNS (Domain Name System) is known that constantly monitors a group of servers of a website operator and returns the IP address of an operating backup server to website visitors if the main server goes down due to a failure or other reason (see, for example, non-patent document 1). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] "IIJ DNS Traffic Management Service", [online], Internet Initiative Japan Inc., [searched on July 20, 2023], Internet<https: / / www.iij.ad.jp / biz / dns-pfm / traffic.html> Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional load balancing systems such as that shown in Non-Patent Document 1, while it is possible to redirect access to a server that is not experiencing any failures, it has not previously been possible to automatically select and provide the IP address of a server that can reduce communication delay time from the access source (user terminal, etc.). [Means for solving the problem]

[0005] According to one aspect of the present invention, there is provided a name resolution method for communication by a user terminal in a mobile communication system, wherein a core network of the mobile communication system comprises a plurality of subnetworks, each configured to provide its own communication area, the name resolution method including: a step in which the user terminal obtains identification information of one or more network devices in a subnetwork among the plurality of subnetworks that corresponds to an area in which the user terminal is located; a step in which the user terminal sends a query to a DNS server including a queried domain name and identification information of the one or more network devices, wherein there are a plurality of server devices corresponding to the queried domain name; a step in which the DNS server identifies an IP address among the IP addresses of the plurality of server devices that correspond to the queried domain name that is associated with the identification information of the one or more network devices included in the query; and a step in which the DNS server transmits the identified IP address to the user terminal as a response to the query.

[0006] In addition, according to one aspect of the present invention, the DNS server is provided with a pre-trained machine learning model configured to input identification information of one or more network devices in one of the multiple subnetworks and output IP addresses corresponding to the identification information of the one or more network devices, and in the identifying step, the DNS server may use the machine learning model to identify an IP address associated with the identification information of the one or more network devices included in the query.

[0007] Furthermore, according to one aspect of the present invention, the IP address identified in the identifying step may be an IP address of a server device that is located in a location physically close to the area where the user terminal is located.

[0008] According to one embodiment of the present invention, the sub-network may include a gateway device that relays user data between the user terminal and an external network of the core network, and the identification information of the one or more network devices may include at least identification information of the gateway device.

[0009] In addition, according to one embodiment of the present invention, the subnetwork may include a user information management device that holds information regarding a user associated with the user terminal, and the identification information of the one or more network devices may include at least identification information of the user information management device.

[0010] According to one aspect of the present invention, the core network may include a subscriber database management device for controlling location registration of the user terminal in the mobile communication system, and the step of the user terminal acquiring the identification information of the one or more network devices in a subnetwork corresponding to the user terminal's location area may include a step in which the user terminal transmits a location registration request signal to the subscriber database management device, a step in which the subscriber database management device establishes a session for the user terminal by designating at least one of the gateway device or the user information management device in the subnetwork corresponding to the user terminal's location area, and a step in which the subscriber database management device transmits a location registration completion notification to the user terminal, the notification including the identification information of the designated at least one of the gateway device or the user information management device.

[0011] According to one aspect of the present invention, there is provided a DNS server for use in conjunction with a mobile communication system, wherein a core network of the mobile communication system comprises a plurality of subnetworks, each configured to provide its own communication area, the DNS server being configured to: receive a query from the user terminal, the query including a queried domain name and identification information of one or more network devices in a subnetwork among the plurality of subnetworks corresponding to an area in which the user terminal is located, where there are a plurality of server devices corresponding to the queried domain name; identify an IP address among the IP addresses of the plurality of server devices corresponding to the queried domain name that is associated with the identification information of the one or more network devices included in the query; and transmit the identified IP address to the user terminal as a response to the query.

[0012] According to another aspect of the present invention, there is provided a user terminal for use in a mobile communication system, wherein a core network of the mobile communication system comprises a plurality of sub-networks, each configured to provide its own communication area, and the user terminal is configured to obtain identification information of one or more network devices in a sub-network among the plurality of sub-networks that corresponds to an area in which the user terminal is located, and to send a query to a DNS server, the query including a domain name to be queried and the identification information of the one or more network devices. Effect of the Invention

[0013] According to the present invention, it is possible to automatically select and provide the IP address of a server that can minimize the communication delay time from the access source. [Brief description of the drawings]

[0014] [Figure 1] 1 is a diagram illustrating an example of a configuration of a network system according to an embodiment of the present invention. [Diagram 2] 1 illustrates an example implementation of a machine learning model provided in a DNS server according to an embodiment of the present invention. [Diagram 3] FIG. 2 is an exemplary sequence diagram showing a process flow in which name resolution is performed by a DNS server in a network system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 is a diagram showing an example of the configuration of a network system 10 according to an embodiment of the present invention. The network system 10 includes a user terminal 100, a mobile communication system 200 configured to provide a mobile communication service to the user terminal 100, and a DNS server 400 for performing name resolution (i.e., conversion from a domain name of a communication partner to an IP address) required when the user terminal 100 communicates with another computer or device via a network 500 such as the Internet.

[0016] In the present disclosure, the user terminal 100 is a mobile device equipped with a function for wirelessly communicating with the mobile communication system 200, and may be provided in the form of, for example, a smartphone, a mobile phone terminal, an in-vehicle wireless communication device, or the like.

[0017] The mobile communication system 200 is composed of a core network 300 and a radio access network including a plurality of base stations (the base stations and the radio access network are not shown in FIG. 1). The core network 300 includes a plurality of nodes (network devices) for providing the user terminal 100 with access to an external network 500. Specifically, FIG. 1 illustrates a mobile communication system 200 conforming to a fifth generation (5G) communication standard, and the core network 300 includes the following nodes: an Access and Mobility Management Function (AMF) 310, a Unified Data Management (UDM) 320, a User Plane Function (UPF) 330, a Session Management Function (SMF) 340, a Policy Control Function (PCF) (not shown in FIG. 1), and a Unified Data Repository (UDR) 350. The mobile communication system 200 may conform to a fourth generation (4G) communication standard.

[0018] The AMF 310 is a node that provides a mobility control function and performs mobility control such as location registration, paging, and handover. The UDM 320 is a node (user information management device) that manages user contract information and authentication information. The UDR 350 is a node (subscriber database management device) that stores a subscriber database that holds the identification number and location information of the user terminal 100. The SMF 340 is a node that provides a session management function and maintains, establishes, changes, and releases sessions. The PCF is a node that provides a policy control function related to quality such as data transfer speed and delay time. The UPF 330 is a node (gateway device) that communicates user data between the user terminal 100 and the external network 500. Each of these nodes complies with the 5G communication standard, and detailed explanations thereof will be omitted here.

[0019] As shown in Fig. 1, a plurality of subdivided subnetworks 301 are formed in a core network 300. In the example of Fig. 1, the core network 300 has N subnetworks, namely, a first subnetwork 301 (#1), a second subnetwork 301 (#2), ..., an Nth subnetwork 301 (#N). Each subnetwork 301 is a network constituting a part of the core network 300, and each subnetwork 301 includes at least one AMF 310, at least one UDM 320, and at least one UPF 330.

[0020] Each AMF 310 and each UPF 330 of each subnetwork 301 is connected to one or more base stations (not shown). Each subnetwork 301 has a unique communication area corresponding to the communication area provided by the one or more base stations. For example, in the example of FIG. 1, the first subnetwork 301 (#1) covers a communication area for region A, the second subnetwork 301 (#2) covers a communication area for region B, and the Nth subnetwork 301 (#N) covers a communication area for region X. The user terminal 100 can connect to any one of the multiple subnetworks through a base station in the communication area in which the user terminal 100 is located. For example, the user terminal 100 connects to the first subnetwork 301 (#1) when it is in region A, and connects to the second subnetwork 301 (#2) when it is in region B.

[0021] In this embodiment, a plurality of Web servers 600 are connected to a network (e.g., the Internet) 500. For example, in the example of FIG. 1, a first Web server 600(#1) is located in a location physically close to a first sub-network 301(#1), a second Web server 600(#2) is located in a location physically close to a second sub-network 301(#2), ..., an Nth Web server 600(#N) is located in a location physically close to an Nth sub-network 301(#N). Each of these Web servers 600(#1), 600(#2), ..., 600(#N) is configured to provide the same content or Web service. Each of the Web servers 600(#1), 600(#2), ..., 600(#N) is assigned a different IP address, but a common (same) domain name is set. That is, the user terminal 100 uses one particular domain name to access any one of these Web servers 600(#1), 600(#2), . . . , 600(#N).

[0022] Here, the Web server 600 being "physically close" to the sub-network 301 means, for example, that the round trip time (RTT) between the UPF 330 (gateway device) of the sub-network 301 and the Web server 600 is short. For example, among the multiple Web servers 600(#1), 600(#2), ..., 600(#N) in Fig. 1, the first Web server 600(#1) has the shortest RTT with the UPF 330 of the first sub-network 301(#1), and similarly, the second Web server 600(#2) has the shortest RTT with the UPF 330 of the second sub-network 301(#2). Therefore, for example, when the user terminal 100 is located in area A (as described above, in this case the user terminal 100 is connected to the first sub-network 301 (#1)), communication delay time can be minimized by controlling the user terminal 100 to access the first Web server 600 (#1) among multiple Web servers 600 that provide the same content or the same Web service.

[0023] The DNS server 400 is configured to respond to an inquiry about an IP address by providing an IP address corresponding to a domain name specified in the inquiry. In this embodiment, the DNS server 400 is further configured to identify the IP address of the Web server 600 that is physically closest to the sub-network 301 of the core network 300 to which the user terminal 100 is connected among the multiple Web servers 600 that provide the same content or the same Web service, and provide the IP address as a response to the inquiry.

[0024] To identify the IP address of the Web server 600 that is physically closest to the sub-network 301 to which the user terminal 100 is connected, the DNS server 400 uses identification information of one or more network devices in the sub-network 301 to which the user terminal 100 is connected. For example, when the user terminal 100 sends an IP address inquiry to the DNS server 400 to access (any of) the Web servers 600, the user terminal 100 specifies the domain name of the Web server 600 as well as the identification information of the UPF 330 (gateway device) and UDM 320 (user information management device) in the sub-network 301 to which the user terminal 100 is connected.

[0025] For example, when user terminal 100 is present in area A and connected to the first subnetwork 301 (#1), user terminal 100 sends an inquiry to DNS server 400 including the domain name of the Web server 600 it is attempting to access, identification information UPF#1 of UPF330 in the first subnetwork 301 (#1), and identification information UDM#1 of UDM320 in the first subnetwork 301 (#1). Furthermore, when the user terminal 100 moves from area A to area B and connects to the second sub-network 301(#2), and continues to access the Web server 600 after the move, the user terminal 100 transmits a query to the DNS server 400, including the domain name of the Web server 600 (the same domain name specified when the user terminal 100 was in area A), the identification information UPF#2 of the UPF 330 in the second sub-network 301(#2), and the identification information UDM#2 of the UDM 320 in the second sub-network 301(#2). Note that the query may include only one of the identification information of the UPF 330 and the identification information of the UDM 320, rather than both.

[0026] Based on the identification information of the network device included in the IP address query (e.g., the identification information of the UPF 330 and / or the identification information of the UDM 320), the DNS server 400 identifies the IP address of the Web server 600 that is physically closest to the sub-network 301 to which the user terminal 100 is connected, among the multiple Web servers 600 to which the domain name specified in the query is set. For example, the DNS server 400 can be configured to realize this process by using a machine learning model that has been trained in advance.

[0027] 2 shows an example of an implementation of a machine learning model 410 provided in the DNS server 400. The machine learning model 410 can be configured by a neural network including an input layer 412 having a plurality of input nodes 411, one or more intermediate layers 414 each having a plurality of nodes 413, and an output layer 416 having a plurality of output nodes 415. Each node is connected to a plurality of nodes in a layer adjacent to the layer to which the node belongs, with a strength characterized by a weighting parameter. For example, identification information of the UPF 330 and identification information of the UDM 320 included in an IP address query are input to the input layer 412. Also, an IP address corresponding to the identification information input to the input layer 412 is output from the output layer 416.

[0028] To train the neural network 410 configured in this manner, teacher data is prepared in advance, with each set being a combination of identification information of the UPF 330 and UDM 320 of each sub-network 301 in the core network 300 and the IP address of the Web server 600 that is physically closest to that sub-network 301. For example, the teacher data may be a first set of data consisting of identification information UPF#1 of UPF 330 and identification information UDM#1 of UDM 320 in the first sub-network 301(#1) and the IP address IPA#1 of the first Web server 600(#1) that is physically closest to the first sub-network 301(#1), identification information UPF#2 of UPF 330 and identification information UDM#2 of UDM 320 in the second sub-network 301(#2) and the IP address IPA#3 of the second Web server 600(#2) that is physically closest to the first sub-network 301(#2), The Nth set of data includes the IP address IPA#2 of the second Web server 600(#2) physically closest to the Nth subnetwork 301(#2), ..., the Nth set of data includes the identification information UPF#N of the UPF 330 and the identification information UDM#N of the UDM 320 in the Nth subnetwork 301(#N) and the IP address IPA#N of the Nth Web server 600(#N) physically closest to the Nth subnetwork 301(#N). The weighting parameters between the nodes of the neural network 410 are adjusted so that the output layer 416 outputs an IP address that matches this teacher data. In this way, the neural network (machine learning model) 410 is trained (learned) in advance.

[0029] The configuration of the neural network shown in FIG. 2 is an example, and is not limited thereto. For example, either the identification information of UPF 330 or the identification information of UDM 320 may be input to the input layer of the neural network. Furthermore, since the identification information of UPF 330 and the identification information of UDM 320 input to the input layer are those of UPF 330 and UDM 320 belonging to the same sub-network 301, and therefore have a high correlation, it may be preferable to use a recurrent neural network as the neural network. Furthermore, the DNS server 400 may realize a similar function by using an appropriate method different from the machine learning model 410, for example, a management table that describes the correspondence between the identification information of the network device (UPF 330 and / or UDM 320) of the sub-network 301 and the IP address of the Web server 600 that is physically closest to the sub-network 301.

[0030] 3 is an exemplary sequence diagram showing a process flow in which name resolution is performed by the DNS server 400 in the network system 10 according to an embodiment of the present invention. In step 1002, the user terminal 100 transmits a location registration request signal including the subscriber identification information (IMSI: International Mobile Subscriber Identity) of the user terminal 100 to a base station in the communication area in which the user terminal 100 is located. The location registration request signal is transferred to the UDR 350 via the AMF 310 and UDM 320 of the sub-network 301 (for example, the first sub-network 301 (#1)) corresponding to that base station (the base station that received the location registration request signal). Note that the location registration request signal may include identification information of the AMF 310 that transfers it.

[0031] Next, in step 1004, UDR 350 designates UPF 330 that is responsible for communication with user terminal 100, and transmits a session establishment instruction to UPF 330. In the following step 1006, UPF 330 confirms the session establishment instruction and returns a session establishment completion notification to UDR 350. Upon receiving the session establishment completion notification from UPF 330, UDR 350 transmits, in step 1008, to user terminal 100, a location registration completion notification including identification information (e.g., UPF#1) of UPF 330 designated in the session establishment instruction in step 1004 and identification information (e.g., UDM#1) of UDM 320 corresponding to the UPF 330. As a result, a data communication path (U-plane) is formed between user terminal 100 and UPF 330 of subnetwork 301 corresponding to the communication area to which user terminal 100 belongs (step 1010).

[0032] Meanwhile, user terminal 100 can obtain identification information (e.g., UPF#1 and UDM#1) of UPF 330 and UDM 320 of subnetwork 301 corresponding to the communication area to which the user terminal 100 belongs by receiving the location registration completion notification sent from UDR 350 in step 1008. In step 1012, in order to know the IP address of Web server 600 that the user terminal 100 wishes to access, the user terminal 100 transmits a query to DNS server 400 including the domain name of Web server 600 and the identification information of UPF 330 and UDM 320 obtained in step 1008.

[0033] In the next step 1014, the DNS server 400 responds to the inquiry from the user terminal 100 by identifying the IP address (e.g., IPA#1) of the Web server 600 that is physically closest to the sub-network 301 (e.g., the first sub-network 301(#1)) to which the user terminal 100 is connected, among the multiple Web servers 600 to which the domain name specified in the inquiry is set, and responds to the user terminal 100. This process in the DNS server 400 has been described above. In this way, the user terminal 100 can obtain the IP address of the Web server 600 that is the desired Web server 600 and is physically closest to the sub-network 301 to which the user terminal 100 is connected, and in step 1016, the user terminal 100 uses this IP address to access the desired Web server 600 (e.g., the first Web server 600(#1)).

[0034] In this way, according to the present disclosure, the user terminal 100 can access the Web server 600 that is physically closest to the sub-network 301 to which the user terminal 100 is connected, thereby minimizing the delay time required for communication. For example, in a system in which the user terminal 100 is an in-vehicle wireless communication device and the Web server 600 provides an automatic driving assistance service using AI (artificial intelligence), the Web server 600 with the minimum communication delay time from the target vehicle for automatic driving assistance can be automatically selected, which is effective in improving the quality of the service. Note that the present disclosure is not limited to the above-mentioned automatic driving assistance system, and can be applied to any system in which a reduction in communication delay time is desired.

[0035] Although the embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications are possible without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0036] 10 Network Systems 100 user terminals 200 Mobile Communication Systems 300 Core Network 301 Subnetwork 310 AMF 320 UDM (User Information Management Device) 330 UPF (Gateway Device) 340 SMF 350 UDR (Subscriber Database Management Device) 400 DNS Server 500 External Network 600 Web Servers

Claims

1. A name resolution method for a user terminal to communicate in a mobile communication system, comprising: The core network of the mobile communication system includes a plurality of sub-networks each configured to provide a unique communication area, and the name resolution method includes: The user terminal acquires identification information of one or more network devices in a subnetwork corresponding to a coverage area of ​​the user terminal among the plurality of subnetworks; a step of the user terminal transmitting a query to a DNS server, the query including a domain name to be queried and identification information of the one or more network devices, where there are a plurality of server devices corresponding to the domain name to be queried; a step of the DNS server identifying an IP address associated with identification information of the one or more network devices included in the query, from among IP addresses of the plurality of server devices corresponding to the domain name of the query target; the DNS server transmitting the identified IP address to the user terminal as a response to the query; A method comprising:

2. the DNS server comprises a pre-trained machine learning model configured to receive as input identification information of one or more network devices in one of the plurality of subnetworks and output IP addresses corresponding to the identification information of the one or more network devices; In the step of identifying, the DNS server identifies an IP address associated with the identification information of the one or more network devices included in the query, using the machine learning model. The method of claim 1.

3. 3. The method according to claim 1, wherein the IP address specified in the specifying step is an IP address of a server device located in a location physically close to the area where the user terminal is located.

4. the subnetwork includes a gateway device that relays user data between the user terminal and an external network of the core network; The identification information of the one or more network devices includes at least identification information of the gateway device. The method of claim 1.

5. The sub-network includes a user information management device that holds information about a user associated with the user terminal; The identification information of the one or more network devices includes at least identification information of the user information management device. The method of claim 1.

6. the core network comprises a subscriber database management device for controlling location registration of the user terminal in the mobile communication system; The step of the user terminal acquiring the identification information of the one or more network devices in a sub-network corresponding to an area where the user terminal is located includes: a step of the user terminal transmitting a location registration request signal to the subscriber database management device; a step of the subscriber database management device designating at least one of the gateway device and the user information management device in a sub-network corresponding to a coverage area of ​​the user terminal, thereby establishing a session for the user terminal; a step of the subscriber database management device transmitting a location registration completion notification including the identification information of at least one of the designated gateway device or the user information management device to the user terminal; The method of claim 4 or 5, comprising:

7. 1. A DNS server for use with a mobile communication system, comprising: The core network of the mobile communication system includes a plurality of sub-networks each configured to provide a unique communication area, and the DNS server receiving, from the user terminal, a query including a domain name to be queried and identification information of one or more network devices in a subnetwork among the plurality of subnetworks corresponding to an area in which the user terminal is located, where there are a plurality of server devices corresponding to the domain name to be queried; Identifying an IP address associated with identification information of the one or more network devices included in the query, from among the IP addresses of the plurality of server devices corresponding to the domain name that is the subject of the query; Transmitting the identified IP address to the user terminal as a response to the inquiry; A DNS server configured to:

8. A user terminal for use in a mobile communication system, comprising: The core network of the mobile communication system includes a plurality of sub-networks each configured to provide a unique communication area, and the user terminal includes: Acquire identification information of one or more network devices in a subnetwork corresponding to an area in which the user terminal is located, among the plurality of subnetworks; sending a query to a DNS server, the query including the domain name being queried and identification information of the one or more network devices; A user terminal configured to:

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