CN113965545A

CN113965545A - DNS request analysis method, communication device and communication system

Info

Publication number: CN113965545A
Application number: CN202010637176.3A
Authority: CN
Inventors: 姚琦; 宗在峰
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2020-07-03
Filing date: 2020-07-03
Publication date: 2022-01-21
Also published as: WO2022001972A1

Abstract

The application provides a DNS request analysis method, a communication device and a communication system. The method comprises the following steps: the method comprises the steps that a shunting network element receives a DNS request from terminal equipment; the shunting network element determines at least one service network according to the first rule and the configuration information of the at least one local network; the shunt network element sends a DNS request to a PSA corresponding to at least one service network; the shunting network element receives response information corresponding to the at least one DNS request, wherein the response information comprises an IP address of the application server; the shunting network element sends the IP address of the first application server to the terminal equipment, and the IP address of the application server received by the shunting network element comprises the IP address of the first application server. Based on the scheme, the shunting network element can select one or more service networks based on the first rule and the configuration information of the local network, and the selected service networks are deployed with the DNS server, so that the situation that the DNS server cannot be analyzed can be avoided, and the analysis success rate of the DNS request is improved.

Description

DNS request analysis method, communication device and communication system

Technical Field

The present application relates to the field of communications technologies, and in particular, to a DNS request analysis method, a communication apparatus, and a communication system.

Background

When a terminal device wants to request a service of an application, if a user wants to use a WeChat service or view a video using an Aichi art APP, the user can click a corresponding function module on the application to trigger a user plane session between the terminal device and a network, then the terminal device sends a Domain Name System (DNS) request to the network, the request carries an application identifier, after receiving the DNS request, a shunting network element sends the DNS request to a local network or a DNS server of a central network to analyze and acquire an Internet Protocol (IP) address of the application server, then the shunting network element sends the IP address to the terminal device, and the terminal device can access the corresponding application server according to the IP address to acquire data content of the application server, so that the service of the application is acquired.

How to improve the resolution success rate of the DNS request in the process of resolving the DNS request is currently needed to be solved.

Disclosure of Invention

The application provides a DNS request analysis method, a communication device and a communication system, which are used for improving the DNS request analysis efficiency.

In a first aspect, an embodiment of the present application provides a DNS request resolution method, including: the method comprises the steps that a shunting network element receives a DNS request from terminal equipment, wherein the DNS request comprises an application identifier, and the DNS request is used for requesting an internet protocol IP address of an application server corresponding to the application identifier; the offloading network element determines at least one service network according to a first rule and configuration information of at least one local network, the service network is deployed with a DNS server, the configuration information of the local network includes capability information of the local network, the capability information of the local network is used for indicating whether the local network is deployed with the local DNS server, and the first rule is a determination rule of the service network; the shunting network element sends the DNS request to a protocol data unit anchor point PSA corresponding to the at least one service network; the shunting network element receives response information corresponding to the at least one DNS request, wherein the response information comprises an IP address of an application server corresponding to the application identifier; the shunting network element sends the IP address of the first application server to the terminal equipment, and the IP address of the application server received by the shunting network element comprises the IP address of the first application server.

Through the scheme, the offloading network element may select one or more service networks based on the configured first rule and the configuration information of the local network, and send the received DNS request to the PSA corresponding to the selected one or more service networks, and since DNS servers are deployed in all the selected service networks, a situation that the DNS request cannot be resolved can be avoided, so that a resolution success rate of the DNS request can be improved.

In a possible implementation method, the first rule is pre-configured on the offloading network element; or, the offloading network element receives the first rule from a session management network element.

In a possible implementation method, the configuration information of the at least one local network is pre-configured on the offload network element; or, the offloading network element receives configuration information of the at least one local network from a session management network element.

In one possible implementation, the first rule is determined according to at least one of a local DNS server deployment of the local network, a resolution capability of a local DNS server, an application server included in the local network, and a location of the local network.

In one possible implementation, the first rule includes at least one of the following rules:

1) if the local network does not deploy a local DNS server, sending the DNS request to a central network;

2) and sending the DNS request to a local network in the at least one local network, wherein the local network is provided with a local DNS server, and sending the DNS request to a central network.

3) And sending the DNS request to one or more local networks with local DNS servers in deployment in the at least one local network.

In one possible implementation, the capability information of the local network is further used to indicate whether a local DNS server supports recursive DNS resolution when the local network is deployed with the local DNS server;

the first rule further comprises at least one of the following rules:

4) if a plurality of local network deployment local DNS servers supporting recursive DNS resolution exist in the at least one local network, selecting one local network from the local network, and sending the DNS request to the selected local network;

5) if only one local network in the at least one local network is provided with a local DNS server supporting recursive DNS resolution, sending the DNS request to the local network;

6) if a plurality of local networks in the at least one local network have local DNS servers supporting recursive DNS resolution, sending the DNS request to the local networks;

7) if a plurality of local network deployment local DNS servers which do not support recursive DNS analysis exist in the at least one local network, selecting one local network from the local network deployment local DNS servers, and sending the DNS request to the selected local network;

8) if only one local network in the at least one local network is provided with a local DNS server which does not support recursive DNS analysis, sending the DNS request to the local network;

9) and if a plurality of local network deployment local DNS servers which do not support recursive DNS resolution exist in the at least one local network, sending the DNS request to the plurality of local networks.

In a possible implementation method, the capability information of the local network is further used for indicating information of an application server deployed by the local network; the first rule further comprises at least one of the following rules:

10) if a plurality of local networks have application servers corresponding to the application identifications and local DNS servers are deployed in the at least one local network, selecting one local network from the at least one local network, and sending the DNS request to the selected local network;

11) if only one local network in the at least one local network has an application server corresponding to the application identifier and the local network has a local DNS server, sending the DNS request to the local network;

12) if one or more local networks have application servers corresponding to the application identifications and are deployed with no local DNS server, the DNS request is sent to a central network;

13) and if the application server corresponding to the application identifier is not deployed in the at least one local network, sending the DNS request to a central network.

In a possible implementation method, the configuration information of the local networks further includes location information or service area information of the local networks, where the location information or service area information is used by the offload network element to select a local network closest to the terminal device from the at least one local network.

Based on the scheme, the IP address of the application server closest to the terminal equipment can be obtained, time delay can be reduced, and user experience is improved.

In a possible implementation method, the IP addresses of the application servers received by the offload network element include multiple IP addresses, and the first application server is an application server that meets the requirement on the distance from the terminal device among the application servers corresponding to the multiple IP addresses. For example, the application server meeting the requirement of the distance from the terminal device may be the application server closest to the terminal device, or the application server with the distance from the terminal device smaller than a preset threshold.

In a second aspect, an embodiment of the present application provides a communication method, including: the session management network element determines a first rule according to at least one of local DNS server deployment of a local network, resolution capability of the local DNS server, an application server contained in the local network and a position of the local network; the session management network element determines a local network which the terminal equipment can access; the session management network element sends configuration information of a local network which can be accessed by the terminal device and the first rule to a offloading network element, wherein the configuration information of the local network comprises capability information of the local network, and the capability information of the local network is used for indicating whether a local DNS server is deployed in the local network.

In a third aspect, an embodiment of the present application provides a communication apparatus, where the apparatus may be a offloading network element, and may also be a chip for offloading the network element. The apparatus has a function of implementing any of the implementation methods of the first aspect. The function can be realized by hardware, and can also be realized by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the functions described above.

In a fourth aspect, an embodiment of the present application provides a communication apparatus, where the apparatus may be a session management network element, and may also be a chip for the session management network element. The apparatus has a function of realizing the second aspect described above. The function can be realized by hardware, and can also be realized by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the functions described above.

In a fifth aspect, an embodiment of the present application provides a communication apparatus, including a processor and a memory; the memory is used for storing computer-executable instructions, and when the apparatus is operated, the processor executes the computer-executable instructions stored in the memory, so that the apparatus executes any of the implementation methods of the first aspect to the second aspect.

In a sixth aspect, an embodiment of the present application further provides a chip system, including: a processor configured to perform any of the implementation methods of the first aspect to the second aspect.

In a seventh aspect, an embodiment of the present application provides a communication apparatus, which includes means or devices (means) for performing each step of any implementation method in the first aspect to the second aspect.

In an eighth aspect, an embodiment of the present application provides a communication device, including a processor and an interface circuit, where the processor is configured to communicate with other devices through the interface circuit, and perform any implementation method of the first aspect to the second aspect. The processor includes one or more.

In a ninth aspect, an embodiment of the present application provides a communication apparatus, including a processor, configured to connect to a memory, and configured to call a program stored in the memory, so as to execute any implementation method of the first aspect to the second aspect. The memory may be located within the device or external to the device. And the processor includes one or more.

In a tenth aspect, embodiments of the present application further provide a computer-readable storage medium, which stores instructions that, when executed on a computer, cause the processor to perform any implementation method of the first aspect to the second aspect.

In an eleventh aspect, the present application further provides a computer program product, where the computer program product includes a computer program, and when the computer program runs, the method of any implementation of the first aspect to the second aspect is executed.

In a twelfth aspect, an embodiment of the present application further provides a communication system, including: the session management network element is used for determining a first rule according to at least one of local DNS server deployment of a local network, resolving capability of the local DNS server, and positions of an application server and the local network contained in the local network; determining a local network which can be accessed by the terminal equipment; and sending configuration information of a local network which can be accessed by the terminal equipment and the first rule to a shunting network element, wherein the configuration information of the local network comprises capability information of the local network, and the capability information of the local network is used for indicating whether a local DNS server is deployed in the local network. A offloading network element, configured to receive, from the session management network element, the configuration information of the local network and the first rule.

Drawings

Fig. 1 is a schematic diagram of a communication system according to an embodiment of the present application;

FIG. 2(a) is a schematic diagram of a 5G network architecture;

FIG. 2(b) is another schematic diagram of a 5G network architecture;

FIG. 3 is an exemplary diagram of a multiple PSA scenario;

fig. 4 is a schematic diagram illustrating a DNS request resolution method according to an embodiment of the present application;

fig. 5 is a schematic diagram of a communication device according to an embodiment of the present application;

fig. 6 is a schematic diagram of another communication device provided in the embodiments of the present application;

fig. 7 is a schematic diagram of another communication device according to an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more clear, the present application will be further described in detail with reference to the accompanying drawings. The particular methods of operation in the method embodiments may also be applied to apparatus embodiments or system embodiments. In the description of the present application, the term "plurality" means two or more unless otherwise specified.

To solve the problems mentioned in the background art, as shown in fig. 1, the present application provides a communication system including a offloading network element and a session management network element.

The session management network element is used for determining a first rule according to at least one of local DNS server deployment of a local network, resolving capability of the local DNS server, and positions of an application server and the local network contained in the local network; determining a local network which can be accessed by the terminal equipment; and sending configuration information of a local network which can be accessed by the terminal equipment and the first rule to a shunting network element, wherein the configuration information of the local network comprises capability information of the local network, and the capability information of the local network is used for indicating whether a local DNS server is deployed in the local network. A offloading network element, configured to receive, from the session management network element, the configuration information of the local network and the first rule.

In a possible implementation method, the offloading network element is further configured to receive a DNS request from the terminal device, where the DNS request includes an application identifier, and the DNS request is used to request an internet protocol IP address of an application server corresponding to the application identifier; determining at least one service network according to the first rule and the configuration information of the local network, wherein the service network is provided with a DNS (domain name system) server; sending the DNS request to a protocol data unit anchor (PSA) corresponding to the at least one service network; receiving response information corresponding to the at least one DNS request, wherein the response information comprises an IP address of an application server; and sending the IP address of the first application server to the terminal equipment, wherein the IP address of the application server corresponding to the application identifier received by the shunting network element comprises the IP address of the first application server. The service network deployment with the DNS server comprises the following scenes: the DNS server may be deployed in a service network, may also be deployed on a UPF/PSA serving the service network, or may also be deployed at a location between the UPF/PSA serving the service network and the service network, where the deployment location of the DNS server is not limited, and the service network may be a local network/edge network or a central network.

In one possible implementation, the capability information of the local network is further used to indicate whether a local DNS server supports recursive DNS resolution when the local network is deployed with the local DNS server; the first rule further comprises at least one of the following rules:

In a possible implementation method, the IP addresses of the application servers received by the offload network element include multiple IP addresses, and the first application server is an application server that meets the requirement on the distance from the terminal device among the application servers corresponding to the multiple IP addresses.

In a possible implementation method, the configuration information of the local networks further includes priority information of the local networks, where the priority information is used by the offloading network element to select a local network with the highest priority from the at least one local network.

The specific implementation of the above scheme will be described in detail in the following method embodiments, and will not be described herein again.

The system shown in fig. 1 may be used in the fifth generation (5th generation, 5G) network architecture shown in fig. 2(a) or fig. 2(b), and of course, may also be used in a future network architecture, such as a sixth generation (6th generation, 6G) network architecture, and the like, which is not limited in this application.

For example, it is assumed that the communication system shown in fig. 1 is applied to a 5G network architecture, and as shown in fig. 2(a), the communication system is a schematic diagram of the 5G network architecture. The network element or entity corresponding to the session management network element in fig. 1 may be a Session Management Function (SMF) network element in the 5G network architecture shown in fig. 2(a), and the network element or entity corresponding to the offloading network element in fig. 1 may be a User Plane Function (UPF) network element in the 5G network architecture shown in fig. 2 (a).

For example, it is assumed that the communication system shown in fig. 1 is applied to a 5G network architecture, and as shown in fig. 2(b), the communication system is a schematic diagram of the 5G network architecture. The network element or entity corresponding to the session management network element in fig. 1 may be an SMF network element in the 5G network architecture shown in fig. 2(a), and the network element or entity corresponding to the offloading network element in fig. 1 may be an Uplink splitter (ULCL) network element in the 5G network architecture shown in fig. 2 (a).

The 5G network architecture shown in fig. 2(a) may include three parts, which are a terminal device part, a Data Network (DN) and an operator network part. The functions of some of the network elements will be briefly described below.

Wherein the operator network may comprise one or more of the following network elements: an Authentication Server Function (AUSF) network element, a network open Function (NEF) network element, a Policy Control Function (PCF) network element, a Unified Data Management (UDM), a Unified Data Repository (UDR), an Application Function (AF) network element, an Access and Mobility Management Function (AMF) network element, an SMF network element, a Radio Access Network (RAN) device, and an UPF network element. In the operator network described above, the parts other than the radio access network part may be referred to as core network parts.

In a specific implementation, the terminal device in the embodiment of the present application may be a device for implementing a wireless communication function. The terminal device may be a User Equipment (UE), an access terminal, a terminal unit, a terminal station, a mobile station, a remote terminal, a mobile device, a wireless communication device, a terminal agent, or a terminal apparatus in a 5G network or a Public Land Mobile Network (PLMN) for future evolution. An access terminal may be a cellular telephone, a cordless telephone, a Session Initiation Protocol (SIP) phone, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA), a handheld device having wireless communication capabilities, a computing device or other processing device connected to a wireless modem, a vehicle mounted device, or a wearable device, a Virtual Reality (VR) terminal device, an Augmented Reality (AR) terminal device, a wireless terminal in industrial control (industrial control), a wireless terminal in self driving (self driving), a wireless terminal in remote medical (remote medical), a wireless terminal in smart grid, a wireless terminal in transportation safety, a wireless terminal in smart city (smart city), a wireless terminal in smart home (smart home), and the like. The terminal may be mobile or stationary.

The terminal device may establish a connection with the carrier network through an interface (e.g., N1, etc.) provided by the carrier network, and use data and/or voice services provided by the carrier network. The terminal device may also access the DN via an operator network, use operator services deployed on the DN, and/or services provided by a third party. The third party may be a service party other than the operator network and the terminal device, and may provide services such as other data and/or voice for the terminal device. The specific expression form of the third party may be determined according to an actual application scenario, and is not limited herein.

The RAN is a sub-network of the operator network and is an implementation system between the service node and the terminal device in the operator network. The terminal device is to access the operator network, first through the RAN, and then may be connected to a service node of the operator network through the RAN. The RAN device in this application is a device that provides a wireless communication function for a terminal device, and is also referred to as an access network device. RAN equipment in this application includes, but is not limited to: next generation base station (G node B, gNB), evolved node B (eNB), Radio Network Controller (RNC), Node B (NB), Base Station Controller (BSC), Base Transceiver Station (BTS), home base station (e.g., home evolved node B, or home node B, HNB), Base Band Unit (BBU), transmission point (TRP), Transmission Point (TP), mobile switching center, etc. in 5G.

The AMF network element mainly performs functions of mobility management, access authentication/authorization and the like. In addition, the method is also responsible for transferring the user policy between the UE and the PCF.

The SMF network element mainly performs the functions of session management, execution of control strategies issued by PCF, UPF selection, UE IP address allocation and the like.

The UPF network element is used as an interface UPF with a data network to complete functions of user plane data forwarding, session/stream level-based charging statistics, bandwidth limitation and the like.

And the UDM network element is mainly responsible for functions of managing subscription data, user access authorization and the like.

And the UDR is mainly responsible for the access function of the type data such as subscription data, strategy data, application data and the like.

The NEF network element is mainly used for supporting the opening of the capability and the event.

The AF network element mainly transfers requirements of an application side on a network side, such as Quality of Service (QoS) requirements or user status event subscriptions. The AF may be a third party functional entity, or may be an application service deployed by an operator, such as an IP Multimedia Subsystem (IMS) voice call service.

The PCF network element is mainly responsible for performing policy control functions such as charging, QoS bandwidth guarantee, mobility management, UE policy decision, etc. for the session and service stream levels.

AUSF network element: it is primarily responsible for authenticating a user to determine whether the user or device is allowed to access the network.

The DN is a network outside the operator network, the operator network can access a plurality of DNs, and the DN can deploy a plurality of services and provide services such as data and/or voice for the terminal device. For example, the DN is a private network of a certain intelligent factory, a sensor installed in a workshop of the intelligent factory can be a terminal device, a control server of the sensor is deployed in the DN, and the control server can provide services for the sensor. The sensor can communicate with the control server, obtain the instruction of the control server, transmit the sensor data gathered to the control server, etc. according to the instruction. For another example, the DN is an internal office network of a company, the mobile phone or computer of the employee of the company may be a terminal device, and the mobile phone or computer of the employee may access information, data resources, and the like on the internal office network of the company.

In the architecture shown in fig. 2(a), the interface names and functions between the network elements are as follows:

1) n7: the interface between the PCF and the SMF is used to send a Protocol Data Unit (PDU) session granularity and a service data stream granularity control policy.

2) N15: and the interface between the PCF and the AMF is used for issuing the UE strategy and the access control related strategy.

3) N5: and the interface between the AF and the PCF is used for issuing the application service request and reporting the network event.

4) N4: the interface between the SMF and the UPF is used for transmitting information between the control plane and the user plane, and comprises the control of issuing of forwarding rules, QoS control rules, flow statistic rules and the like facing the user plane and the information reporting of the user plane.

5) N11: and the interface between the SMF and the AMF is used for transmitting PDU session tunnel information between the RAN and the UPF, transmitting control information sent to the UE, transmitting radio resource control information sent to the RAN and the like.

6) N2: and the interface between the AMF and the RAN is used for transmitting radio bearer control information from the core network side to the RAN and the like.

7) N1: an interface between the AMF and the terminal equipment, for delivering QoS control rules to the UE, etc.

8) N8: and the interface between the AMF and the UDM is used for acquiring the subscription data and the authentication data related to access and mobility management from the UDM by the AMF, registering the current mobility management related information of the UE from the UDM by the AMF and the like.

9) N10: and the interface between the SMF and the UDM is used for acquiring the subscription data related to the session management from the SMF to the UDM, registering the related information of the current session of the UE from the SMF to the UDM, and the like.

10) N35: and the interface between the UDM and the UDR is used for acquiring the user subscription data information from the UDR by the UDM.

11) N36: and the interface between the PCF and the UDR is used for the PCF to acquire the subscription data related to the strategy and the application data related information from the UDR.

12) N12: the interface between the AMF and the AUSF is used for initiating an authentication process from the AMF to the AUSF, wherein the SUCI can be carried as a subscription identifier;

13) n13: and the interface between the UDM and the AUSF is used for acquiring the user authentication vector from the UDM by the AUSF so as to execute the authentication process.

It is to be understood that the above network elements or functions may be network elements in a hardware device, or may be software functions running on dedicated hardware, or virtualization functions instantiated on a platform (e.g., a cloud platform). Optionally, the network element or the function may be implemented by one device, or may be implemented by multiple devices together, or may be a functional module in one device, which is not specifically limited in this embodiment of the present application.

The session management network element and the user plane network element in this application may be the SMF and UPF (such as ULCL, PSA1 and PSA2) in fig. 2(a) or fig. 2(b), respectively, or may be network elements having the above-mentioned functions of SMF and UPF in future communication such as a 6G network, which is not limited in this application. For convenience of description, the session management network element and the user plane network element are respectively the SMF and the UPF, which are taken as examples for description in the present application.

Based on the above architecture, the 5G network architecture shown in fig. 2(a) has only one UPF, and the 5G further supports inserting one or more protocol data unit Anchor points (PDU Session anchors, PSAs) UPFs on a user plane path of one PDU Session to support connection to a local network (or referred to as an Edge data network, or referred to as a Mobile Edge Computing (MEC) network, or referred to as a local data network, or referred to as an MEC), so that the terminal device can access applications in the local data network nearby. Wherein each PSA is a UPF.

On the basis of fig. 2(a), a plurality of UPFs may be introduced, resulting in a 5G network architecture as shown in fig. 2 (b). Wherein part of the network elements in fig. 2(a) are not shown in fig. 2 (b). The introduced plurality of UPFs include: ULCL UPF, PSA UPF1, and PSA UPF-2. It should be noted that fig. 2(b) is only an example, and in practical applications, the number of PSAs is not limited, and may be one, two, or more than two.

In this embodiment of the present application, the offloading network element may be a ULCL UPF, which may also be referred to as a ULCL, an offloading Point (BP), a BP UPF, and the like, and all of which are denoted by ULCL below.

In the examples of the present application, psauff may be referred to as UPF PSA or PSA, and will be referred to as PSA hereinafter. Thus, the PSA UPF1 and PSA UPF2 may also be referred to as PSA1 and PSA 2.

The ULCL is configured to distribute upstream packets received from the end device to PSA1 or PSA2 and to send downstream packets received from PSA1 or PSA2 to the end device according to a distribution rule.

PSA1 has an N6 interface with a DN, which may be, for example, a DN located at a central Data Center (DC), in which case PSA1 may also be referred to as a central PSA (C-PSA) or a remote PSA. PSA2 has an N6 interface with a local DN, which may be a DN located in a local DC (i.e., MEC network), for example, in which case PSA2 may also be referred to as a local PSA (L-PSA).

When a UPF (such as PSA2 described above) is present at the location of the terminal device that has access to the local DN, the SMF may insert the UPF into the session path as an L-PSA so that the terminal device may have near-field access to applications in the local DN. Fig. 2(b) above shows only one L-PSA (i.e., PSA2), and in practice multiple L-PSAs may be included.

As shown in fig. 3, which is an exemplary diagram of a plurality of PSA scenarios. Among them, ULCL can connect a plurality of L-PSAs, and two L-PSAs (i.e., L-PSA1 and L-PSA2) are exemplified in the figure. In this example, L-PSA1 is connected to local network 1, L-PSA2 is connected to local network 2, and C-PSA is connected to a central network (also referred to as a central data network, central DC, far-end network, far-end data network, etc.). Furthermore, a DNS server is deployed in the local network 1, a DNS server is not deployed in the local network 2, and a DNS server is deployed in the central network. Herein, the DNS server deployed in the Local network may also be referred to as an edge DNS server or a Local (Local) DNS server, the Local DNS server in the Local network is hereinafter denoted by L-DNS, the DNS server deployed in the central network may also be referred to as a central (center) DNS server, and the central DNS server in the central network is hereinafter denoted by C-DNS.

In the existing network, the L-DNS may be deployed in conjunction with UPF serving the local network, e.g., in the example of FIG. 3, local network 1 may be deployed in conjunction with L-PSA1, local network 2 may be deployed in conjunction with L-PSA2, and the ULCL may be deployed in conjunction with some L-PSA, e.g., ULCL is deployed in conjunction with L-PSA 1.

The L-DNS deployed in the local network can be used to resolve DNS requests corresponding to application servers in the local network. The L-DNS deployed in the local network may have a connection (i.e., may be interworking) with the C-DNS server deployed in the central network, or may have no connection (i.e., may not be interworking) with the C-DNS deployed in the central network.

When a terminal device wants to request a service of an application, for example, a user wants to use a WeChat service or watch a video using the Airy APP, the user may click on a corresponding function module on the application, thereby triggering a user plane session between the terminal device and the network, and then the terminal device sends a DNS request to the network, where the request carries an application identifier (e.g., a Fully Qualified Domain Name (FQDN)), and the ULCL, upon receiving the DNS request, sends the DNS request to a PSA, for example, to L-PSA1, and then L-PSA1 sends the DNS request to L-DNS in the local network 1, where the L-DNS queries an IP address corresponding to the application identifier and sends the IP address to L-1, L-PSA1 sends the IP address to the ULCL, and the ULCL sends the IP address to the terminal device via the RAN, so that the terminal device can access the corresponding application server according to the IP address, to obtain the data content of the application server and thus obtain the service of the application.

The IP address here is an IP address of an application server corresponding to the application identifier, and specifically may be an IP address of the application server in the central network and/or an IP address of the application server in one or more local networks. For example, if the application is a WeChat, the acquired IP address is the IP address of the WeChat application server. Generally, when a local network or a central network deploys a DNS server and an application server, the DNS server stores therein a mapping relationship between an application identifier and an IP address of the application server. Taking the local network 1 in fig. 3 as an example, if the local network 1 is deployed with a wechat application server, an odds art application server, and a Tencent application server, the DNS server of the local network 1 stores the mapping relationship between the wechat domain name and the IP address of the wechat application server, the mapping relationship between the odds art domain name and the IP address of the odds art application server, and the mapping relationship between the Tencent domain name and the IP address of the Tencent application server.

Generally, an application server for the same application may be deployed in a central network, and in order to provide a near service for a user to improve user experience, the application server may also be deployed in one or more local networks while the central network deploys the application server. Taking fig. 3 as an example, the Tencent application server may be deployed in the central network, and may also be deployed in local network 1 and/or local network 2.

The following describes possible situations and problems that may occur during an actual DNS request.

When the ULCL receives a DNS request (carrying an application identity) and needs to send the DNS request to a PSA, there are several situations:

case 1, no DNS server is deployed in the local network corresponding to the PSA

Referring to fig. 3, such as ULCL sends DNS requests to L-PSA2, but the local network to which L-PSA2 corresponds does not deploy a DNS server, so L-PSA2 cannot send DNS requests to the corresponding DNS server, resulting in the DNS request not being resolved.

Case 2, a DNS server is deployed in a local network corresponding to the PSA

When a DNS server is deployed in the local network to which the PSA corresponds, the DNS server in the local network can resolve the DNS request. Case 2 can be further divided into the following cases 2.1 and 2.2 according to whether the local network is deployed with the application server corresponding to the application identifier in the DNS request.

Case 2.1, the application server corresponding to the application identifier in the DNS request is deployed in the local network corresponding to the PSA

Referring to fig. 3, such as ULCL sending DNS requests to L-PSA1, the local network to which L-PSA1 corresponds deploys a DNS server, so L-PSA1 can send DNS requests to DNS servers in local network 1, which DNS servers can resolve the DNS requests.

When an application server corresponding to the application identifier in the DNS request is deployed in the local network 1, the DNS server of the local network 1 stores a corresponding relationship between the application identifier and the IP address of the application server, so that the DNS server can successfully resolve and obtain the IP address of the application server.

Case 2.2, the application server corresponding to the application identifier in the DNS request is not deployed in the local network corresponding to the PSA

Referring to fig. 3, such as ULCL sending DNS requests to L-PSA1, local network 1 to which L-PSA1 corresponds deploys a DNS server, so L-PSA1 can send DNS requests to DNS servers in local network 1, which can resolve the DNS requests.

When the local network 1 does not deploy the application server corresponding to the application identifier in the DNS request, the DNS server of the local network 1 may not store the correspondence between the application identifier and the IP address of the application server, and therefore the DNS server cannot successfully resolve and obtain the IP address of the application server.

For this case 2.2, it is further possible to divide this case 2.2 into the following cases 2.2.1 and 2.2.2, depending on whether there is a connection (i.e., interworking) between the DNS server in the local network and the DNS server in the central network.

Case 2.2.1, there is a connection between a DNS server deployed in the local network and a DNS server deployed in the central network

When there is a connection between the DNS server deployed in the MEC and the DNS server deployed in the central network, and the DNS server in the local network fails to resolve the application identifier in the DNS request, the DNS request may be sent to the DNS server in the central network, and the DNS server in the central network resolves the application identifier in the DNS request. That is, in this case, the DNS server in the local network supports recursive resolution. The DNS server deployed in the central network does not refer to the C-DNS in fig. 3, but refers to a DNS server that has DNS resolution capability and has an interface with the DNS server in the local network, that is, after the DNS server in the local network sends a DNS request to the DNS server, the DNS server can resolve the DNS request.

Generally, the DNS server in the central network is deployed with an application server corresponding to the application identifier, so that the resolution can be successful. And the DNS server in the central network stores a mapping relationship between an application identifier and IP addresses of a plurality of application servers, where the plurality of application servers include an application server located in the central network and an application server located in the local network.

After the DNS server in the central network successfully resolves the application domain name, the corresponding IP address is sent to the DNS server deployed in the local network, and then the L-PSA corresponding to the local network is sent to the ULCL, and further sent to the terminal equipment.

It should be noted that, in such a recursive manner, an IP address obtained by resolution by the DNS server in the central network may not be an optimal IP address, that is, an application server corresponding to the IP address may not be an application server closest or closer to the terminal device, and thus, user experience may be poor. In an implementation method, when a DNS server in a local network fails to resolve an application identifier in a DNS request, the DNS request may be sent to a DNS server in a central network, and the DNS request also carries location information of a terminal device, so that the DNS server in the central network can resolve the DNS request based on the location information of the terminal device, and an IP address obtained by the resolution is closer to the terminal device.

Case 2.2.2, there is no connection between a DNS server deployed in the local network and a DNS server deployed in the central network

In this case, the DNS server deployed in the local network cannot resolve the DNS request, and the DNS server deployed in the central network cannot be requested to resolve the DNS request, the resolution fails.

The above are various situations that may occur when the ULCL sends the DNS request to different PSAs, and in principle, if the DNS server in the local network can resolve, the DNS server in the local network should resolve, because the DNS server in the local network can obtain the IP address of an application server closest to the terminal device, whereas if the DNS server in the central network resolves, on one hand, the path is far, which causes a delay, and on the other hand, the application server corresponding to the IP address resolved by the DNS server in the central network may not be the application server closest to the terminal device, which causes a poor user experience.

As can be seen from the above analysis of various situations, on one hand, when the ULCL sends the received DNS request to the corresponding PSA, it may eventually be impossible to resolve the DNS request (as in the above cases 1 and 2.2.2), so that the ULCL needs to reselect a PSA and send the DNS request to the PSA, which causes signaling waste, and on the other hand, if the ULCL initially sends the DNS request to the central PSA, the application server corresponding to the IP address resolved by the central DNS server may not be the application server closest to the terminal device, which results in poor user experience.

Therefore, how to improve the resolution efficiency of the DNS request (such as improving the resolution success rate, reducing the number of DNS requests, etc.) is to be solved by the present application.

In order to solve the above-mentioned problems, the present application provides a resolution method of DNS request based on the network architecture shown in fig. 2(b) or fig. 3, as shown in fig. 4. In this embodiment, a terminal device is taken as an example of a UE for explanation. This embodiment is described in connection with the network architecture shown in fig. 3. In practical applications, the embodiments of the present application are not limited to the network architecture shown in fig. 3. The embodiment of the application can be applied to the situation that one local network, two local networks or more than two local networks are deployed.

The method comprises the following steps:

in step 401, the SMF configures a first rule and configuration information of the local network.

The local network here may be one or more local networks. The local network may also be referred to as an edge network, an MEC, a local data network, etc.

The first rule (which may also be referred to as a DNS request forwarding rule, a determination rule, or the like) may be configured on the SMF by an administrator through the network management system, or may also be determined by the SMF. For example, the SMF determines the first rule based on at least one of an L-DNS deployment of the local network, a resolution capability of the L-DNS, a location of an application server and the local network included in the local network.

The configuration information of the local network may be configured on the SMF by an administrator through a network management system, or may be determined by the SMF. The configuration information of the local network at least comprises capability information of the local network, and the capability information of the local network is used for indicating whether the local network is provided with the L-DNS or not.

Optionally, the capability information of the local network is further used to indicate whether the L-DNS supports recursive DNS resolution when the local network is deployed with L-DNS. Wherein, when an interface exists between the L-DNS and the C-DNS, the L-DNS supports recursive resolution.

Optionally, the capability information of the local network is also used for indicating information of the application server deployed by the local network.

Optionally, the configuration information of the local network further includes location information or service area information of the local network. The location information or service Area information of the local network may be represented by Tracking Area Identifier (TAI) for indicating a location where the local network is located.

In step 402, the UE creates a PDU session.

At this time, the SMF has not inserted the ULCL in the PDU session yet, and the current user plane path of the PDU session is: UE < - > RAN < - > C-PSA.

At step 403, the SMF inserts into the ULCL.

The SMF may be inserted during the UE creating session or dynamically after the UE creates the session.

The triggering event that triggers the insertion of an SMF into a ULCL may be: SMF detects UE movement, SMF receives DNS request from C-PSA, or receives notification from PCF, etc.

At step 404, the SMF sends the first rule and configuration information of the local network to the ULCL. Accordingly, the ULCL may receive the first rule and configuration information for the local network.

The SMF creates an N4 session between the SMF and the ULCL and then sends the first rule and the configuration information of the local network to the ULCL over an N4 session, which may determine from the first rule and the configuration information of the local network to send the received DNS request to the corresponding UPF, which may be an L-PSA and/or a C-PSA.

It should be noted that, if the current location of the UE has multiple local networks accessible, that is, the location of the UE is in the coverage of the multiple local networks, the SMF sends the first rule and the configuration information of the multiple local networks to the ULCL.

As one implementation, the SMF may determine a home network accessible to the UE that created the PDU session, and then send the first rule and configuration information of the home network accessible to the UE to the ULCL.

At step 405, the ULCL configures the first rule and configuration information for the local network.

And after receiving the first rule and the configuration information of the local network, the ULCL configures the first rule and the configuration information of the local network on the ULCL.

After configuring the first rule and the configuration information of the local network on the ULCL, the ULCL may determine to which UPF to forward the received DNS request based on the first rule and the configuration information of the local network.

It should be noted that, as another implementation method, the first rule on the ULCL may also be preconfigured on the ULCL, for example, may be preconfigured by an administrator through a network management system. When the first rule on the ULCL is pre-configured on the ULCL, there is no need to configure the first rule to the ULCL through the SMF.

As another implementation method, the configuration information of the local network on the ULCL may also be preconfigured on the ULCL, for example, may be preconfigured by an administrator through a network management system. When the configuration information of the local network on the ULCL is pre-configured on the ULCL, the configuration information of the local network does not need to be configured to the ULCL through the SMF.

At step 406a, SMF is inserted into L-PSA1, creating a tunnel between the ULCL and L-PSA 1.

As shown in fig. 4, in order that a user plane connection with the local network 1 may be established, L-PSA1 may be inserted into a user plane path of a PDU session of the UE and a tunnel between the ULCL and L-PSA1 is created, thereby establishing a user plane path: UE RAN L-PSA1 home network 1.

At step 406b, SMF is inserted into L-PSA2, creating a tunnel between the ULCL and L-PSA 2.

As shown in fig. 4, in order that a user plane connection with the local network 2 may be established, L-PSA2 may be inserted into a user plane path of a PDU session of the UE and a tunnel between the ULCL and L-PSA2 is created, thereby establishing a user plane path: UE RAN L-PSA2 home network 2.

At step 407, the ULCL receives the DNS request.

The DNS request is sent by the UE to the RAN, which sends the DNS request to the ULCL.

The DNS request comprises an application identifier, and the DNS request is used for requesting to query the IP address of an application server corresponding to the application identifier.

At step 408, the ULCL determines at least one serving network for receiving the DNS request.

The service network here may be a home network or a central network. The service network is deployed with a DNS server.

For example, when the serving network is a local network, L-DNS is deployed. Optionally, one or more application servers (i.e., local application servers) may also be deployed in the local network. One local network corresponds to one or more L-PSA, or the one or more L-PSA serve the local network, and the L-PSA and the local network can be deployed together or separately. Optionally, an interface exists between the L-DNS and the C-DNS of the central network, and the L-DNS supports recursive resolution, that is, a received DNS request may be forwarded to the L-DNS for resolution.

When the service network is a central network, a C-DNS is deployed. Optionally, one or more application servers (i.e., central application servers) may also be deployed in the central network. One central network corresponds to one or more C-PSAs, or the one or more C-PSAs provide services for the central network, and the C-PSAs and the central network can be deployed together or separately. Optionally, an interface exists between the C-DNS and the L-DNS of one or more local networks, and the C-DNS may receive a DNS request sent by the one or more local networks and send an IP address obtained by resolution to the L-DNS of the local network after resolving the DNS request.

In this step 408, it is determined by the ULCL which DNS server within which network or networks is needed to resolve the DNS request.

As one implementation, the ULCL may determine the at least one serving network based on the first rule and the configuration information of the at least one local network, and may further determine a PSA (e.g., L-PSA and/or C-PSA) corresponding to the at least one serving network, respectively.

As an example, when the capability information of the local network in the configuration information of the local network configured on the ULCL is used to indicate whether the local network is deployed with L-DNS, the first rule configured on the ULCL includes, but is not limited to, at least one of:

a first rule 1, if no L-DNS is deployed in any local network accessible to the UE, sends a DNS request to the central network.

That is, if no L-DNS is deployed in any local network accessible to the UE, the DNS request is sent to the C-PSA corresponding to the central network, and the C-PSA sends the DNS request to the C-DNS of the central network for resolution.

Based on the first rule, the DNS request is not sent to the L-PSA corresponding to the local network without the L-DNS, but is directly sent to the C-PSA corresponding to the central network, so that the resolution success rate of the DNS request can be improved, and the resolution efficiency is further improved.

A first rule 2, sending DNS requests to local networks deployed with L-DNS among local networks accessible to the UE, and to the central network. Optionally, priorities between the plurality of local networks and the central network may be predefined, such that when the ULCL receives IP addresses from the plurality of networks, one may be selected from the received plurality of IP addresses according to the priorities.

Based on the first rule, the ULCL sends the received DNS request to the local networks and to the central network, instead of sending the DNS request to only one local network or only to the central network, that is, requests to resolve the DNS request to a plurality of service networks at a time, so the resolution success rate of the DNS request can be increased, and the resolution efficiency can be further increased.

A first rule 3, sending DNS requests to one or more of the local networks accessible to the UE, where L-DNS is deployed. Optionally, priorities among the plurality of local networks may be predefined, such that when the ULCL receives IP addresses from the plurality of networks, one may be selected from the received plurality of IP addresses according to the priorities.

Based on the first rule, the ULCL sends the received DNS requests to the local networks and the central network instead of only one local network, namely, requests to analyze the DNS requests from a plurality of service networks at each time, so that the resolution success rate of the DNS requests can be improved, and the resolution efficiency is further improved.

As an example, when the capability information of the local network in the configuration information of the local network configured on the ULCL is also used to indicate whether the L-DNS supports recursive DNS resolution when the local network is deployed with L-DNS, the first rule configured on the ULCL may further include, but is not limited to, at least one of:

a first rule 4 is that, if there are a plurality of local networks to which the UE can access and L-DNS supporting recursive DNS resolution is deployed, one local network is selected from the local networks, and a DNS request is sent to the selected local network.

That is, the DNS request is sent to the L-PSA corresponding to the selected local network, and the L-PSA sends the DNS request to the L-DNS in the local network for resolution.

Based on the first rule, on one hand, the ULCL only sends the received DNS request to the L-PSA corresponding to one local network, but not to the L-PSAs corresponding to multiple local networks, that is, only one network is requested to resolve the DNS request at a time, so that the DNS resolution times can be reduced, signaling overhead is reduced, and resolution efficiency is improved. On the other hand, the DNS request is sent to the L-PSA corresponding to the local network of the L-DNS supporting the recursive DNS resolution, so that the resolution success rate of the DNS request is improved, and the DNS resolution efficiency is further improved.

A first rule 5, if there is only one local network among the local networks accessible to the UE, where L-DNS supporting recursive DNS resolution is deployed, sends a DNS request to the local network.

That is, the ULCL sends the DNS request to the L-PSA corresponding to the local network, which sends the DNS request to the L-DNS in the local network for resolution.

A first rule 6 is to send a DNS request to a plurality of local networks accessible to the UE if the local networks have the L-DNS deployed therein that supports recursive DNS resolution. Alternatively, priorities among the plurality of local networks may be predefined, so that when the ULCL receives IP addresses from the plurality of local networks, one may be selected from the received plurality of IP addresses according to the priorities.

That is, the ULCL may send DNS requests to the L-PSAs corresponding to the plurality of local networks, respectively, and the L-PSAs send the DNS requests to the L-DNS in the corresponding local networks, respectively, for resolution.

Based on the first rule, on one hand, the ULCL sends the received DNS request to the L-PSA corresponding to each of the local networks, instead of sending the DNS request to only one L-PSA corresponding to one local network, that is, requests a plurality of local networks to resolve the DNS request at a time, so that the success rate of DNS resolution can be increased, and the resolution efficiency can be further improved. On the other hand, the DNS request is sent to the L-PSA corresponding to the local network of the L-DNS supporting the recursive DNS resolution, so that the resolution success rate of the DNS request is improved, and the DNS resolution efficiency is further improved.

A first rule 7 is that, if there are a plurality of local networks in the local networks accessible to the UE and L-DNS is deployed that do not support recursive DNS resolution, one local network is selected from the local networks, and a DNS request is sent to the selected local network.

That is, the ULCL sends the DNS request to the L-PSA corresponding to the selected one of the local networks, and the L-PSA sends the DNS request to the L-DNS in the local network for resolution. If the resolution fails, one other local network is selected from the plurality of local networks, the DNS request is sent to the L-PSA corresponding to the other local network, and the L-PSA sends the DNS request to the L-DNS in the other local network for resolution. And repeating the steps until the resolution is successful or all resolutions are failed, sending the DNS request to the C-PSA corresponding to the central network, and sending the DNS request to the C-DNS of the central network for resolution by the C-PSA.

Based on the first rule, the ULCL only sends the received DNS request to the L-PSA corresponding to one local network or the C-PSA corresponding to the central network, but not to the L-PSA corresponding to a plurality of local networks, namely only one network is requested to analyze the DNS request at each time, so that the DNS analysis times can be reduced, the signaling overhead is reduced, and the analysis efficiency is improved.

A first rule 8 is to send a DNS request to a local network if there is only one local network among the local networks accessible to the UE that has an L-DNS deployed that does not support recursive DNS resolution.

That is, the ULCL sends the DNS request to the L-PSA corresponding to the local network, which sends the DNS request to the L-DNS in the local network for resolution. And if the resolution fails, sending the DNS request to a C-PSA corresponding to the central network, and sending the DNS request to a C-DNS of the central network for resolution by the C-PSA.

A first rule 9 is to send DNS requests to a plurality of local networks accessible to the UE if the local networks have L-DNS deployed therein that do not support recursive DNS resolution. Alternatively, priorities among the plurality of local networks may be predefined, so that when the ULCL receives a plurality of IP addresses, one may be selected from the received plurality of IP addresses according to the priorities.

That is, the ULCL sends the DNS request to the L-PSA corresponding to the plurality of local networks respectively, and the L-PSA sends the DNS request to the L-DNS in the corresponding local network respectively for resolution. And if the L-DNS corresponding to the local networks fails to resolve, sending the DNS request to a C-PSA corresponding to the central network, and sending the DNS request to the C-DNS of the central network for resolving by the C-PSA.

Based on the first rule, the ULCL sends the received DNS request to the L-PSA corresponding to the local networks, instead of sending the DNS request to the L-PSA corresponding to one local network, namely, requests to resolve the DNS request to the local networks at each time, so that the success rate of DNS resolution can be improved, and the resolution efficiency is further improved.

As an example, when the capability information of the local network in the configuration information of the local network configured on the ULCL is also used for indicating the information of the application server deployed by the local network, the information of the application server deployed by the local network is used for indicating which application servers are deployed in the local network, such as the application server deployed can be indicated by an application identifier (such as FQDN). The first rule configured on the ULCL may further include, but is not limited to, at least one of:

a first rule 10 is that, if a plurality of local networks, in which application servers corresponding to application identifiers are deployed, exist in a local network accessible to the UE and a plurality of local networks, each of which has an L-DNS deployed therein, one local network is selected from the plurality of local networks, and a DNS request is sent to the selected local network.

That is, the ULCL sends the DNS request to the L-PSA corresponding to the selected local network, which sends the DNS request to the L-DNS in the local network for resolution.

Based on the first rule, on one hand, the ULCL only sends the received DNS request to the L-PSA corresponding to one local network, but not to the L-PSAs corresponding to multiple local networks, that is, only one network is requested to resolve the DNS request at a time, so that the DNS resolution times can be reduced, signaling overhead is reduced, and resolution efficiency is improved. On the other hand, since the local network is deployed with the application server corresponding to the application identifier in the DNS request, the success rate of DNS request resolution is improved, and thus the DNS resolution efficiency is further improved.

A first rule 11 is to send a DNS request to a local network if there is only one local network to which an application server corresponding to an application identity is deployed among local networks accessible to the UE, and the local network is deployed with L-DNS.

A first rule 12 is to send a DNS request to a central network if one or more local networks with application identifiers deployed therein exist in local networks accessible to the UE, and none of the one or more local networks has L-DNS deployed.

That is, the ULCL sends the DNS request to the C-PSA corresponding to the central network, and the C-PSA sends the DNS request to the C-DNS in the central network for resolution. Optionally, the location information or service area information of the one or more local networks is also sent to the C-DNS, so that the C-DNS can select an application server closest to the UE according to the location information or service area information of the one or more local networks.

Based on the first rule, on one hand, the ULCL only sends the received DNS request to the C-PSA corresponding to the central network, but not to the PSAs corresponding to the plurality of networks, that is, only one network is requested to resolve the DNS request at a time, so that the number of DNS resolution can be reduced, signaling overhead is reduced, and resolution efficiency is improved. On the other hand, because the central network is deployed with the application server corresponding to the application identifier in the DNS request, the success rate of DNS request resolution is improved, and thus the DNS resolution efficiency is further improved. On the other hand, unnecessary signaling overhead can be reduced by not sending DNS requests to local networks that do not deploy L-DNS.

The first rule 13 is to send a DNS request to the central network if no application server corresponding to the application identifier is deployed in any local network accessible to the UE.

That is, the ULCL sends the DNS request to the C-PSA corresponding to the central network, and the C-PSA sends the DNS request to the C-DNS of the central network for resolution.

Based on the first rule, on one hand, the ULCL only sends the received DNS request to the C-PSA corresponding to the central network, but not to the PSAs corresponding to a plurality of networks (e.g., one or more local networks, the central network), that is, only one network is requested to resolve the DNS request at a time, so that the DNS resolution times can be reduced, the signaling overhead can be reduced, and the resolution efficiency can be improved. On the other hand, the C-DNS of the central network can analyze and obtain the IP address of the application server, so that the success rate of DNS request analysis is improved, and the DNS analysis efficiency is further improved.

Optionally, if the configuration information of the local networks configured on the ULCL further includes location information or service area information of the local network, in the first rule, if the ULCL needs to select one local network from the plurality of local networks, the ULCL may select one local network closest to the UE from the plurality of local networks based on the location information or service area information of the local network.

Optionally, if the configuration information of the local networks configured on the ULCL further includes priority information of the local networks, the priority information being used for the ULCL to select a local network with highest priority from at least one local network, in the first rule, if the ULCL needs to select a local network from a plurality of local networks, the ULCL may select a local network from the plurality of local networks based on the priority information of the local networks.

Optionally, if it is determined to send the DNS request to the C-DNS according to the first rule, the ULCL may further carry the location information of the terminal device in the DNS request, so that the C-DNS may resolve the DNS request based on the location information of the terminal device, and the resolved IP address is closer to the terminal device.

It should be noted that, if a plurality of first rules are configured on the ULCL, the priority between these first rules may be set in advance.

It should be noted that the first rule may be configured based on UE granularity, that is, the first rules configured by different UEs may be the same or different. Alternatively, the first rule may be configured on a per-UPF granularity basis, that is, the first rules configured by different UEs of the same UPF service are the same, but the first rules configured by different UEs of different UPF services may be the same or different.

The following steps 409a to 409b are optional steps. If it is determined in the above step 408 that the serving network for receiving the DNS request includes the local network 1, the following steps 409a and 409b are performed. If it is determined in step 408 that the serving network unit for receiving the DNS request includes the local network 1, the following steps 409a and 409b are not performed.

At step 409a, ULCL sends a DNS request to L-PSA1 corresponding to local network 1. Accordingly, the L-PSA1 may receive the DNS request.

Referring to fig. 4, L-PSA1, upon receiving the DNS request, sends the DNS request to the L-DNS in local network 1 for resolution.

When the L-DNS in the local network 1 successfully resolves the DNS request, that is, the IP address of the application server corresponding to the application identifier in the DNS request is obtained, the L-DNS in the local network 1 sends the IP address to the L-PSA1, then the L-PSA1 sends the IP address to the ULCL, the ULCL sends the IP address to the RAN, and the RAN sends the IP address to the UE.

When the L-DNS resolution in the local network 1 fails, if there is an interface between the L-DNS in the local network 1 and the C-DNS in the central network, the DNS request may be sent to the C-DNS for resolution, then the C-DNS sends the resolution result (i.e., the IP address of the application server) to the L-DNS in the local network 1, then the L-DNS in the local network 1 sends the IP address to the L-PSA1, the L-PSA1 sends the IP address to the ULCL, and then the ULCL sends the IP address to the RAN, and the RAN sends the IP address to the UE.

At step 409b, L-PSA1 sends a response message to the ULCL. Accordingly, the ULCL may receive the response information.

Note that when the response message includes an IP address (which may be obtained by L-DNS resolution of local network 1 or C-DNS resolution), it indicates that L-PSA1 successfully resolves the DNS request. When the response message does not contain an IP address, it indicates that L-PSA1 failed to resolve the DNS request.

The following steps 410a to 410b are optional steps. If it is determined in the above step 408 that the service network for receiving the DNS request includes the central network, the following steps 410a to 410b are performed. If it is determined in the above step 408 that the service network for receiving the DNS request does not include the central network, the following steps 410a to 410b are not performed.

At step 410a, the ULCL sends a DNS request to the C-PSA corresponding to the central network. Accordingly, the C-PSA may receive the DNS request.

Referring to fig. 4, after receiving the DNS request, the C-PSA sends the DNS request to the C-DNS of the central network for resolution. Generally, the central network is deployed with an application server corresponding to the application identifier, so that the resolution can be successful. And the C-DNS stores a mapping relation between an application identification and IP addresses of a plurality of application servers, wherein the plurality of application servers comprise an application server located in a central network and an application server located in a local network.

And after the C-DNS successfully resolves the application domain name, the corresponding IP address is sent to the C-PSA, the C-PSA sends the IP address to the ULCL, the ULCL sends the IP address to the RAN, and the RAN sends the IP address to the UE.

At step 410b, the C-PSA sends a response message to the ULCL. Accordingly, the ULCL may receive the response information.

It should be noted that, when the response message contains an IP address, it indicates that the resolution of the DNS request by the C-DNS is successful. When the DNS reply does not contain an IP address, the C-DNS fails to resolve the DNS request.

In step 411, if the ULCL receives a plurality of IP addresses, it determines an IP address.

For example, if the ULCL sends a DNS request to a plurality of UPFs (e.g., one or more L-PSAs, C-PSAs), a response message is received from each UPF, some response messages carry an IP address (i.e., resolution is successful), some response messages do not carry an IP address (i.e., resolution is failed), and if the ULCL receives a plurality of IP addresses, an IP address (referred to as an IP address of the first application server) is selected from the response messages.

As an implementation method, the first application server may be an application server closest to the UE.

At step 412, the ULCL sends the IP address to the UE. Accordingly, the UE may receive the IP address.

That is, the ULCL sends the IP address of the first application server to the UE.

With the above scheme, the ULCL can select one or more serving networks based on the configured first rule and the configuration information of the local network, and send the received DNS request to the PSA corresponding to the selected one or more serving networks. For example, when the DNS request is sent to a selected plurality of service networks, the resolution success rate of the DNS request can be increased. For another example, when the DNS request is sent to a local network in which a DNS server is deployed, or sent to a local network in which a DNS server with recursive resolution capability is deployed, the resolution success rate can also be increased. Therefore, the success rate of DNS resolution can be improved by the scheme. Meanwhile, the IP address of the application server closest to the terminal equipment can be obtained, so that time delay can be reduced, and user experience is improved.

The above-mentioned scheme provided by the present application is mainly introduced from the perspective of interaction between network elements. It is to be understood that the above-described implementation of each network element includes, in order to implement the above-described functions, a corresponding hardware structure and/or software module for performing each function. Those of skill in the art will readily appreciate that the present invention can be implemented in hardware or a combination of hardware and computer software, with the exemplary elements and algorithm steps described in connection with the embodiments disclosed herein. Whether a function is performed as hardware or computer software drives hardware depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

It is to be understood that, in the foregoing embodiments of the methods, the steps or operations implemented by the access network device may also be implemented by a component (e.g., a chip or a circuit) configured in the access network device, the steps or operations implemented by the user plane network element may also be implemented by a component (e.g., a chip or a circuit) configured in the user plane network element.

Fig. 5 is a schematic diagram of a communication device according to an embodiment of the present disclosure. The apparatus is configured to implement the steps performed by the corresponding offloading network element (i.e. ULCL) in the embodiment of fig. 4, as shown in fig. 5, the apparatus 500 includes a receiving unit 510, a sending unit 520, and a processing unit 530.

A receiving unit 510, configured to receive a DNS request from a terminal device, where the DNS request includes an application identifier, and the DNS request is used to request an internet protocol IP address of an application server corresponding to the application identifier; and receiving response information corresponding to the at least one DNS request, wherein the response information comprises the IP address of the application server corresponding to the application identification. A processing unit 530, configured to determine at least one serving network in which a DNS server is deployed according to a first rule and configuration information of at least one local network, where the configuration information of the local network includes capability information of the local network, the capability information of the local network is used to indicate whether the local network is in which the local DNS server is deployed, and the first rule is a determination rule of the serving network. A sending unit 520, configured to send the DNS request to a PSA (protocol data unit) anchor corresponding to the at least one serving network; and sending the IP address of a first application server to the terminal equipment, wherein the IP address of the application server received by the shunting network element comprises the IP address of the first application server.

In a possible implementation method, the first rule is pre-configured on the offloading network element; alternatively, the receiving unit 510 is further configured to receive the first rule from a session management network element.

In a possible implementation method, the configuration information of the at least one local network is pre-configured on the offload network element; alternatively, the receiving unit 510 is further configured to receive configuration information of the at least one local network from a session management network element.

the first rule further comprises at least one of the following rules:

In a possible implementation method, the configuration information of the local networks further includes location information or service area information of the local networks, and the location information or service area information is used to select a local network closest to the terminal device from the at least one local network.

In a possible implementation method, the IP address of the application server received by the receiving unit 510 includes multiple IP addresses, and the first application server is an application server that meets the requirement of distance from the terminal device among application servers corresponding to the multiple IP addresses.

Optionally, the communication device 500 may further include a storage unit, which is used for storing data or instructions (also referred to as codes or programs), and the above units may interact with or be coupled to the storage unit to implement corresponding methods or functions. For example, the processing unit 530 may read data or instructions in the storage unit, so that the communication device implements the method in the above-described embodiments.

It should be understood that the division of the units in the above apparatus is only a division of logical functions, and the actual implementation may be wholly or partially integrated into one physical entity or may be physically separated. And the units in the device can be realized in the form of software called by the processing element; or may be implemented entirely in hardware; part of the units can also be realized in the form of software called by a processing element, and part of the units can be realized in the form of hardware. For example, each unit may be a processing element separately set up, or may be implemented by being integrated into a chip of the apparatus, or may be stored in a memory in the form of a program, and a function of the unit may be called and executed by a processing element of the apparatus. In addition, all or part of the units can be integrated together or can be independently realized. The processing element described herein may in turn be a processor, which may be an integrated circuit having signal processing capabilities. In the implementation process, the steps of the method or the units above may be implemented by integrated logic circuits of hardware in a processor element or in a form called by software through the processor element.

In one example, the units in any of the above apparatuses may be one or more integrated circuits configured to implement the above methods, such as: one or more Application Specific Integrated Circuits (ASICs), or one or more microprocessors (DSPs), or one or more Field Programmable Gate Arrays (FPGAs), or a combination of at least two of these Integrated Circuit formats. As another example, when a Unit in a device may be implemented in the form of a Processing element scheduler, the Processing element may be a general-purpose processor, such as a Central Processing Unit (CPU) or other processor capable of invoking programs. As another example, these units may be integrated together and implemented in the form of a system-on-a-chip (SOC).

The above receiving unit 510 is an interface circuit of the apparatus, and is used for receiving signals from other apparatuses. For example, when the apparatus is implemented in the form of a chip, the receiving unit 510 is an interface circuit for the chip to receive signals from other chips or apparatuses.

The above transmitting unit 520 is an interface circuit of the apparatus, and is used to transmit signals to other apparatuses. For example, when the device is implemented in the form of a chip, the transmitting unit 520 is an interface circuit for the chip to transmit signals to other chips or devices.

Fig. 6 is a schematic diagram of a communication device according to an embodiment of the present disclosure. The apparatus is configured to implement the steps performed by the corresponding session management network element (i.e., SMF) in the embodiment of fig. 4, as shown in fig. 6, the apparatus 600 includes a transceiver unit 610 and a processing unit 620.

A processing unit 620, configured to determine a first rule according to at least one of a local DNS server deployment of a local network, a resolving capability of a local DNS server, an application server included in the local network, and a location of the local network; a local network that the terminal device is able to access is determined. A transceiving unit 610, configured to send, to a offload network element, configuration information of a local network to which the terminal device can access and the first rule, where the configuration information of the local network includes capability information of the local network, and the capability information of the local network is used to indicate whether a local DNS server is deployed in the local network.

Optionally, the communication device 600 may further include a storage unit, which is used for storing data or instructions (also referred to as codes or programs), and the above units may interact with or be coupled to the storage unit to implement corresponding methods or functions. For example, the processing unit 620 may read data or instructions in the storage unit, so that the communication device implements the method in the above-described embodiments.

In one example, the units in any of the above apparatuses may be one or more integrated circuits configured to implement the above methods, such as: one or more ASICs, or one or more DSPs, or one or more FPGAs, or a combination of at least two of these integrated circuit forms. As another example, when a unit in a device may be implemented in the form of a processing element scheduler, the processing element may be a general purpose processor, such as a CPU or other processor capable of invoking programs. As another example, these units may be integrated together, implemented in the form of an SOC.

The above transceiving unit 610 is an interface circuit of the apparatus, and is used to transmit signals to or receive signals from other apparatuses. For example, when the device is implemented in the form of a chip, the transceiving unit 610 is an interface circuit for the chip to transmit signals to other chips or devices or to receive signals from other chips or devices.

Referring to fig. 7, a schematic diagram of a communication apparatus provided in this embodiment is used to implement operations of a session management network element or a offload network element in the foregoing embodiments. As shown in fig. 7, the communication apparatus includes: a processor 710 and an interface 730, and optionally, the communication device further includes a memory 720. Interface 730 is used to enable communication with other devices.

The method executed by the session management network element or the offloading network element in the above embodiments may be implemented by the processor 710 calling a program stored in a memory (which may be the memory 720 in the session management network element or the offloading network element, or may be an external memory). That is, the session management network element or the forking network element may include the processor 710, and the processor 710 may execute the method executed by the session management network element or the forking network element in the above method embodiment by calling a program in a memory. The processor here may be an integrated circuit with signal processing capabilities, such as a CPU. The session management network element or the forking network element can be implemented by one or more integrated circuits configured to implement the above methods. For example: one or more ASICs, or one or more microprocessors DSP, or one or more FPGAs, etc., or a combination of at least two of these integrated circuit forms. Alternatively, the above implementations may be combined.

In particular, the functions/implementation processes of the receiving unit 510, the sending unit 520, and the processing unit 530 in fig. 5 may be implemented by the processor 710 in the communication device 700 illustrated in fig. 7 calling the computer executable instructions stored in the memory 720. Alternatively, the function/implementation procedure of the processing unit 530 in fig. 5 may be implemented by the processor 710 in the communication apparatus 700 shown in fig. 7 calling a computer executing instruction stored in the memory 720, and the function/implementation procedure of the receiving unit 510 and the sending unit 520 in fig. 5 may be implemented by the interface 730 in the communication apparatus 700 shown in fig. 7.

In particular, the functions/implementation processes of the transceiving unit 610 and the processing unit 620 in fig. 6 may be implemented by the processor 710 in the communication device 700 illustrated in fig. 7 calling the computer executable instructions stored in the memory 720. Alternatively, the function/implementation procedure of the processing unit 620 in fig. 6 may be implemented by the processor 710 in the communication device 700 shown in fig. 7 calling a computer executing instruction stored in the memory 720, and the function/implementation procedure of the transceiving unit 610 in fig. 6 may be implemented by the interface 730 in the communication device 700 shown in fig. 7.

Those of ordinary skill in the art will understand that: the various numbers of the first, second, etc. mentioned in this application are only used for the convenience of description and are not used to limit the scope of the embodiments of this application, but also to indicate the sequence. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. "at least one" means one or more. At least two means two or more. "at least one," "any," or similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, at least one (one ) of a, b, or c, may represent: a, b, c, a-b, a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple. "plurality" means two or more, and other terms are analogous.

It should be understood that, in the various embodiments of the present application, the sequence numbers of the above-mentioned processes do not mean the execution sequence, and the execution sequence of the processes should be determined by their functions and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the application to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website site, computer, server, or data center to another website site, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device including one or more available media integrated servers, data centers, and the like. The usable medium may be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others.

The various illustrative logical units and circuits described in this application may be implemented or operated upon by design of a general purpose processor, a digital signal processor, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other similar configuration.

The steps of a method or algorithm described in the embodiments herein may be embodied directly in hardware, in a software element executed by a processor, or in a combination of the two. The software cells may be stored in Random Access Memory (RAM), flash Memory, Read-Only Memory (ROM), EPROM Memory, EEPROM Memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. For example, a storage medium may be coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

In one or more exemplary designs, the functions described herein may be implemented in hardware, software, firmware, or any combination of the three. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media that facilitate transfer of a computer program from one place to another. Storage media may be any available media that can be accessed by a general purpose or special purpose computer. For example, such computer-readable media can include, but is not limited to, RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store program code in the form of instructions or data structures and which can be read by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Additionally, any connection is properly termed a computer-readable medium, and, thus, is included if the software is transmitted from a website, server, or other remote source over a coaxial cable, fiber optic computer, twisted pair, Digital Subscriber Line (DSL), or wirelessly, e.g., infrared, radio, and microwave. The disk (disk) and Disc (Disc) include compact Disc, laser Disc, optical Disc, Digital Versatile Disc (DVD), floppy disk and blu-ray Disc, where the disk usually reproduces data magnetically, and the Disc usually reproduces data optically with laser. Combinations of the above may also be included in the computer-readable medium.

Those skilled in the art will recognize that in one or more of the examples described above, the functions described herein may be implemented in hardware, software, firmware, or any combination thereof. When implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer.

The above-mentioned embodiments, objects, technical solutions and advantages of the present application are further described in detail, it should be understood that the above-mentioned embodiments are only examples of the present application, and are not intended to limit the scope of the present application, and any modifications, equivalent substitutions, improvements and the like made on the basis of the technical solutions of the present application should be included in the scope of the present application. The foregoing description of the specification may enable any person skilled in the art to make or use the teachings of the present application, and any modifications based on the disclosed teachings should be considered as obvious in the art, and the general principles described herein may be applied to other variations without departing from the spirit or scope of the present application. Thus, the disclosure is not intended to be limited to the embodiments and designs described, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Although the present application has been described in conjunction with specific features and embodiments thereof, it will be evident that various modifications and combinations can be made thereto without departing from the spirit and scope of the application. Accordingly, the specification and figures are merely exemplary of the present application as defined in the appended claims and are intended to cover any and all modifications, variations, combinations, or equivalents within the scope of the present application. It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include such modifications and variations.

Claims

1. A resolution method for a Domain Name System (DNS) request is characterized by comprising the following steps:

the method comprises the steps that a shunting network element receives a DNS request from terminal equipment, wherein the DNS request comprises an application identifier, and the DNS request is used for requesting an internet protocol IP address of an application server corresponding to the application identifier;

the offloading network element determines at least one service network according to a first rule and configuration information of at least one local network, the service network is deployed with a DNS server, the configuration information of the local network includes capability information of the local network, the capability information of the local network is used for indicating whether the local network is deployed with the local DNS server, and the first rule is a determination rule of the service network;

the shunting network element sends the DNS request to a protocol data unit anchor point PSA corresponding to the at least one service network;

the shunting network element receives response information corresponding to the at least one DNS request, wherein the response information comprises an IP address of an application server corresponding to the application identifier;

the shunting network element sends the IP address of the first application server to the terminal equipment, and the IP address of the application server received by the shunting network element comprises the IP address of the first application server.

2. The method of claim 1, wherein the first rule is pre-configured on the offload network element; or,

the offloading network element receives the first rule from a session management network element.

3. The method according to claim 1 or 2, wherein the configuration information of the at least one local network is pre-configured on the forking network element; or,

the offloading network element receives configuration information of the at least one local network from a session management network element.

4. A method according to any of claims 1-3, wherein the first rule is determined according to at least one of a local DNS server deployment of the local network, a resolution capability of a local DNS server, an application server comprised by the local network and a location of the local network.

5. The method of any of claims 1-4, wherein the first rule comprises at least one of the following rules:

2) sending the DNS request to a local network which is provided with a local DNS server in the at least one local network, and sending the DNS request to a central network;

6. The method of claim 5, wherein the capability information of the local network is further used to indicate whether a local DNS server supports recursive DNS resolution when the local network is deployed with the local DNS server;

the first rule further comprises at least one of the following rules:

7. The method of claim 5, wherein the capability information of the local network is further used for information indicating application servers deployed by the local network;

the first rule further comprises at least one of the following rules:

8. The method according to claim 6 or 7, wherein the configuration information of the local networks further comprises location information or service area information of the local networks, the location information or service area information being used by the forking network element to select a local network closest to the terminal device from the at least one local network.

9. The method according to any one of claims 1 to 7, wherein the IP address of the application server received by the offload network element includes multiple IP addresses, and the first application server is an application server that meets the requirement of distance from the terminal device among application servers corresponding to the multiple IP addresses.

10. A communications apparatus, comprising:

a receiving unit, configured to receive a DNS request from a terminal device, where the DNS request includes an application identifier, and the DNS request is used to request an internet protocol IP address of an application server corresponding to the application identifier; receiving response information corresponding to the at least one DNS request, wherein the response information comprises an IP address of an application server corresponding to the application identifier;

the processing unit is used for determining at least one service network according to a first rule and configuration information of at least one local network, the service network is provided with a DNS (domain name system) server, the configuration information of the local network comprises capability information of the local network, the capability information of the local network is used for indicating whether the local network is provided with the local DNS server, and the first rule is a determination rule of the service network;

a sending unit, configured to send the DNS request to a PSA (protocol data unit) anchor corresponding to the at least one serving network; and sending the IP address of a first application server to the terminal equipment, wherein the IP address of the application server received by the shunting network element comprises the IP address of the first application server.

11. The apparatus of claim 10, wherein the first rule is pre-configured on the offload network element; or,

the receiving unit is further configured to receive the first rule from a session management network element.

12. The apparatus according to claim 10 or 11, wherein the configuration information of the at least one local network is pre-configured on the forking network element; or,

the receiving unit is further configured to receive configuration information of the at least one local network from a session management network element.

13. An arrangement according to any of claims 10-12, wherein said first rule is determined based on at least one of local DNS server deployment of said local network, resolution capabilities of local DNS servers, application servers comprised by said local network and location of said local network.

14. The apparatus of any of claims 10-13, wherein the first rule comprises at least one of:

15. The apparatus of claim 14, wherein the capability information of the local network is further for indicating whether a local DNS server supports recursive DNS resolution when the local network is deployed with the local DNS server;

the first rule further comprises at least one of the following rules:

16. The apparatus of claim 14, wherein the capability information of the local network is further for indicating information of application servers deployed by the local network;

the first rule further comprises at least one of the following rules:

17. The apparatus according to claim 15 or 16, wherein the configuration information of the local networks further comprises location information or service area information of the local networks, the location information or service area information being used to select a local network closest to the terminal device from the at least one local network.

18. The apparatus according to any of claims 10-16, wherein the IP address of the application server received by the receiving unit includes a plurality of IP addresses, and the first application server is an application server satisfying a distance requirement with respect to the terminal device among application servers corresponding to the plurality of IP addresses.

19. A communication system, comprising:

the session management network element is used for determining a first rule according to at least one of local DNS server deployment of a local network, resolving capability of the local DNS server, and positions of an application server and the local network contained in the local network; determining a local network which can be accessed by the terminal equipment; sending configuration information of a local network which can be accessed by the terminal equipment and the first rule to a shunting network element, wherein the configuration information of the local network comprises capability information of the local network, and the capability information of the local network is used for indicating whether a local DNS server is deployed in the local network;

a offloading network element, configured to receive, from the session management network element, the configuration information of the local network and the first rule.

20. The system of claim 19, wherein the offload network element is further configured to:

receiving a DNS request from the terminal equipment, wherein the DNS request contains an application identifier, and the DNS request is used for requesting an internet protocol IP address of an application server corresponding to the application identifier;

determining at least one service network according to the first rule and the configuration information of the local network, wherein the service network is provided with a DNS (domain name system) server;

sending the DNS request to a protocol data unit anchor (PSA) corresponding to the at least one service network;

receiving response information corresponding to the at least one DNS request, wherein the response information comprises an IP address of an application server corresponding to the application identifier;

and sending the IP address of a first application server to the terminal equipment, wherein the IP address of the application server received by the shunting network element comprises the IP address of the first application server.

21. The system of claim 19 or 20, wherein the first rule comprises at least one of the following rules:

22. The system of claim 21, wherein the capability information of the local network is further to indicate whether a local DNS server supports recursive DNS resolution when the local network is deployed with the local DNS server;

the first rule further comprises at least one of the following rules:

23. The system of claim 21, wherein the capability information of the local network is further for indicating information of application servers deployed by the local network;

the first rule further comprises at least one of the following rules:

24. The system according to claim 22 or 23, wherein the configuration information of the local networks further comprises location information or service area information of the local networks, the location information or service area information being used by the forking network element to select a local network closest to the terminal device from the at least one local network.

25. The system according to any of claims 19 to 24, wherein the IP address of the application server received by the offload network element includes a plurality of IP addresses, and the first application server is an application server that meets the requirement for distance from the terminal device among application servers corresponding to the plurality of IP addresses.

26. A computer-readable storage medium, characterized by comprising a computer program which, when run on a computer, causes the computer to perform the communication method according to any one of claims 1-9.

27. A computer program product, characterized in that the computer program product comprises a computer program which, when run on a computer, causes the computer to carry out the communication method according to any one of claims 1-9.