CN100466846C - Method and system for accessing home packet data network - Google Patents

Abstract

The embodiment of the present invention discloses a method and system for accessing a home packet data network. When a mobile terminal roams to a visited location and uses the access point name (APN) to initiate a packet service request, the service of the visited location The general packet radio service support node SGSN equipment interacts with the electronic code domain name service system ENUM DNS equipment to obtain the IP address or domain name of the gateway general packet radio service support node GGSN corresponding to the mobile terminal identifier; The GGSN at the home location initiates a service request, thereby accessing the packet data network at the corresponding home location. In addition, when the mobile number carries MNP in the whole network, the mobile terminal can also access the packet data network at the home location. In addition, the introduction of ENUM DNS equipment can be compatible with the original standard domain name system DNS domain name resolution mechanism.

Description

Method and system for accessing home packet data network

technical field

The invention relates to the communication field, in particular to a method and system for accessing a home packet data network.

Background technique

Mobile packet data services are widely used rapidly due to their advantages such as convenient mobility, high-speed transmission rate, and rich mobile data services, as defined by the standard protocol of 3GPP (3rd Generation Partnership Project, third-generation mobile communication standardization partner project) GPRS (General Packet Radio Service, general packet radio service)/WCDMA (Wide (band) Code Division Multiple Access, wideband code division multiple access) system can enable mobile terminals to access packet data services. In these systems, SGSN (Serving GPRS Support Node, service GPRS support node), GGSN (Gateway GPRS Support Node, gateway GPRS support node) and DNS (Domain Name System, Domain Name System) equipment in the system are connected through the Gn interface , to implement communication between these devices, so the network connecting the Gn interfaces of the devices can also be referred to as a Gn network.

When the mobile terminal accesses the packet data service through the GPRS/WCDMA network, it usually specifies the packet data network or service type to be accessed through the carried APN (Access Point Name, access point name). If the APN carried by the mobile terminal is not a specific name, but a wildcard "*", then the GPRS/WCDMA network will finally determine the specific APN by the SGSN in a manner defined by the 3GPP standard protocol.

The APNs can generally be classified into general APNs (or public APNs) and regional APNs (or private APNs). A general APN is an APN that can be identified and used in all areas of the entire PLMN (Public Land Mobile Network) network, and a regional APN is an APN that can be identified and used only in some areas.

Assume that the mobile terminal MS_A belongs to A. APNs named xxxx and yyyy are generic APNs. As shown in Figure 1, a typical mobile terminal uses a general APN packet data service access process.

The access process for MS_A to access the Internet at the location A is as follows:

①. MS_A initiates a packet data service request to SGSN_A through the wireless access network, and the requested APN is xxxx;

②. SGSN_A constructs the domain name corresponding to APN: xxxx according to the protocol, and initiates a DNS request to DNS_A to obtain the GGSN address;

③. According to the configuration, DNS_A returns the IP address of GGSN_A corresponding to APN: xxxx to SGSN_A;

④. SGSN_A initiates a service request to GGSN_A;

⑤. GGSN_A connects the user to the corresponding packet data network PDN_A according to APN: xxxx. Through the above process, the packet data service access process of the mobile terminal at the home location is realized.

If mobile terminal MS_A roams to area B and initiates a packet data service in area B where it roams, the access process is as follows:

①. MS_A initiates a packet data service request to SGSN_B through the wireless access network, and the requested APN is xxxx;

②. SGSN_B constructs the domain name corresponding to APN: xxxx according to the protocol, and initiates a DNS request to DNS_B to obtain the GGSN address;

③. DNS_B returns the IP address of GGSN_B corresponding to APN: xxxx to SGSN_B according to the configuration;

④. SGSN_B initiates a service activation request to GGSN_B;

⑤. GGSN_B connects the user to the corresponding packet data network PDN_B according to APN: xxxx.

Through the above process, it is realized that the mobile terminal can access the packet data network of the visiting place in the case of roaming.

It can be seen from the above that when a mobile terminal uses a general-purpose APN to initiate a packet data service, the packet data network accessed during roaming is different from the packet data network accessed at home, which may prevent the mobile terminal from enjoying The local business ordered by its attribution, or the quality of service cannot be guaranteed.

In order to solve the problem that the mobile terminal cannot access the home packet data network by using the common APN in the roaming situation, the key is how to find the GGSN at the home place of the mobile terminal. The prior art related to the present invention provides a method of home access in the roaming situation, and its main idea is: on the SGSN of the visited place, configure the IMSI (International Mobile Subscriber Identifier, International Mobile Subscriber Identifier) of the mobile terminal Symbol)/MSISDN (Mobile Station International Integrated Services Digital Network Number, mobile station International Integrated Services Digital Network Number) number segment and the corresponding relationship between the home GGSNIP address/domain name, when the visiting SGSN handles the packet data service request of the mobile terminal, Obtain the home GGSN IP address/domain name corresponding to the IMSI/MSISDN number section of the mobile terminal by judging the configuration information of the number segment, and then initiate a service request to the home GGSN, thereby realizing home access in the case of roaming.

As can be seen from the technical solutions of the prior art, it has the following defects:

1. It is necessary to configure the correspondence table between the IMSI/MSISDN number segment and the GGSN IP address/domain name of the home location on all the SGSNs in the visited location. The data configuration workload is very heavy; and once the network structure changes, or the IMSI/MSISDN number segment If there is a change, it is necessary to update the corresponding relationship tables on all SGSNs, and the workload of network maintenance is huge.

2. In the case of cross-area MNP (Mobile Number Portable) or cross-operator MNP requirements, there will be no direct correspondence between the MSISDN number segment and the area to which it belongs, and the corresponding GGSN cannot be found through the MSISDN number segment. Therefore, if the corresponding relationship between the MSISDN number segment and the GGSN is configured on the SGSN in the prior art, it cannot meet the attribution access requirement of the packet data service in the case of implementing the MNP.

Contents of the invention

The embodiment of the present invention provides a method and system for accessing the home packet data network. Through the embodiment of the present invention, the mobile terminal can access the home packet data network even if the general APN is used in the case of roaming. .

Embodiments of the present invention are achieved through the following technical solutions:

An embodiment of the present invention provides a method for accessing a home packet data network, which includes:

After receiving the service request sent by the mobile terminal roaming to the visited place using the APN, the SGSN device in the visited place interacts with the ENUM DNS device to obtain the resource record of the domain name corresponding to the mobile terminal identifier, and obtains the resource record based on the resource record analysis. The mobile terminal identifies the IP address or domain name of the corresponding home GGSN; and initiates a service request to the home GGSN according to the IP address or domain name;

The GGSN at the home location sends the mobile terminal's request to access the packet data network at the home location corresponding to the APN.

Embodiments of the present invention also provide a system for accessing a home packet data network, which includes:

Visited SGSN equipment, home GGSN equipment, and ENUM DNS equipment

The visited SGSN device is used to receive the service request sent by the mobile terminal roaming to the visited place using APN, interact with the ENUM DNS device to obtain the resource record of the domain name corresponding to the mobile terminal identifier, and according to the resource record Analyzing and obtaining the IP address or domain name of the home GGSN corresponding to the mobile terminal identifier; and initiating a service request to the home GGSN device according to the IP address or domain name;

The home GGSN equipment accesses the mobile terminal's request to the home packet data network corresponding to the APN.

Embodiments of the present invention also provide a serving general packet radio service support node device, which includes:

The processing unit is configured to obtain the resource record of the domain name corresponding to the mobile terminal identifier by interacting with the ENUM DNS device after receiving the service request sent by the mobile terminal roaming to the visited place using the APN, and obtain the resource record by parsing the resource record. The IP address or domain name of the attribution GGSN corresponding to the mobile terminal identifier;

The requesting unit is configured to initiate a service request to the home GGSN according to the IP address or domain name.

It can be seen from the specific implementation scheme provided by the above-mentioned embodiments of the present invention that when the mobile terminal roams to the visited place and uses APN to initiate a service request, the SGSN device of the visited place obtains the mobile terminal from the ENUM DNS device through the SGSN device of the visited place. The IP address or domain name of the GGSN at the corresponding home location; and initiate a service request to the GGSN at the home location according to the IP address or domain name, thereby accessing the packet data network at the corresponding home location. Therefore, when the mobile terminal is roaming, it can also access the packet data network at home by using the general APN.

Description of drawings

FIG. 1 is a schematic diagram of a service flow when a mobile terminal accesses a home packet data network using a general-purpose APN provided by the background technology;

FIG. 2 is a schematic diagram of the service flow when the mobile terminal accesses the packet data network at the home site from the home site using a general-purpose APN in the first embodiment provided by the present invention;

FIG. 3 is a schematic diagram of the service flow when the mobile terminal accesses the packet data network of the home location from the visiting location using a common APN in the first embodiment provided by the present invention;

Fig. 4 is the structural principle diagram of the second embodiment provided by the present invention;

Fig. 5 is the structural schematic diagram of the third embodiment provided by the present invention;

Fig. 6 is a structural principle diagram of the fourth embodiment provided by the present invention.

Detailed ways

ENUM (Electronic NUMbering, electronic encoding) is a protocol defined by the IETF Telephone Number Mapping working group (Telephone Number Mapping working group) - RFC2916, the title of RFC2916 is "E.164 Number and Domain Name System (E.164 Number and DNS) )". It defines the method to convert the E.164 number into the domain name form and put it in the database of the DNS device. E.164 numbers are important resources used in traditional telecommunication networks, and DNS equipment is an important foundation of the Internet. ENUM combines the two. Each domain name converted from an E.164 number can correspond to a series of uniform resource identifiers (Uniform Resource Identifier, URI), so that the internationally unified E.164 number becomes a network address resource that can be used in the Internet. ENUM can use the E.164 number to look up the Registrant's e-mail, IP phone number, unified message, IP fax or personal web page and other information.

Based on the above considerations, the embodiment of the present invention introduces the ENUM DNS device defined in the international standard to replace the common DNS device in the Gn network. By configuring the resource record of the domain name corresponding to the mobile terminal identifier in the ENUM DNS device, the mobile terminal identifier and the domain name are established. The corresponding relationship between the APN and the GGSN of the home location is used to realize the access of the mobile terminal to the network of the home location in the case of roaming.

The ENUM standard protocol defines how to convert the number conforming to the E.164 format into a domain name form. Therefore, the mobile terminal identification of the present invention only needs to conform to the E.164 format. For example, IMSI and MSISDN are all mobile phone numbers conforming to the E.164 format. Terminal ID.

The first embodiment provided by the present invention is a method for accessing a home packet data network, the main idea of which is: when a mobile terminal roams to a visited location and uses a general APN to initiate a request, the From the ENUM DNS device, the SGSN device obtains the IP address or domain name of the GGSN at the corresponding home location identified by the mobile terminal; and initiates a service request to the GGSN at the home location according to the IP address or domain name, thereby accessing the GGSN at the corresponding home location packet data network.

Before implementing the first embodiment, the resource record of the domain name corresponding to the mobile terminal identifier needs to be configured in the ENUM DNS device, including the corresponding relationship between the APN and the GGSN IP address of the mobile terminal's home, or the APN and the mobile terminal's home The corresponding relationship of the domain name of the GGSN.

In addition, the ENUM DNS client function is added to SGSN: convert the mobile terminal identifier into a domain name according to the ENUM standard protocol, and send a domain name resolution request to the ENUM DNS device, and resolve the GGSN IP address corresponding to the APN from the resource record returned by the ENUM DNS device .

Assume that the home area of the mobile terminal MS_A is A. The mobile terminal MS_A roams to the visited area B. The specific implementation process of the first embodiment will be described below using the packet data service access process of the mobile terminal MS_A in the home area A and the packet data service access process of the mobile terminal MS_A in the visited area B.

The packet data service access process of mobile terminal MS_A at home A is shown in Figure 2:

Step ①, MS_A initiates a packet data service request to SGSN_A through the wireless access network, and the requested general APN is xxxx;

Step ②, SGSN_A constructs a corresponding domain name according to the mobile terminal identifier, and initiates an ENUM DNS resolution request to ENUM DNS_A;

Step ③, ENUM DNS_A returns the resource record corresponding to the domain name to SGSN_A according to the configuration information;

Step ④, SGSN_A resolves the IP address of the attribution GGSN_A corresponding to the APN:xxxx from the resource record, and initiates a service request to GGSN_A;

In step ⑤, the GGSN_A connects the user to the corresponding home packet data network PDN_A according to the APN, so as to realize the packet data service access process of the mobile terminal at the home location.

After the mobile terminal MS_A roams to the visited area B, the packet data service access process in the visited area B is shown in Figure 3:

Step ①, MS_A initiates a packet data service request to the visited SGSN_B through the wireless access network, and the requested general APN is xxxx;

Step ②, SGSN_B constructs a corresponding domain name according to the mobile terminal identifier, and initiates an ENUM DNS resolution request to ENUM DNS_B;

Step 3. If the resource record of the domain name is configured in ENUM DNS_B, skip directly to step 7. If there is no record of the domain name configured in ENUM DNS_B, the standard domain name resolution method is used to request domain name resolution to the upper-level ENUM DNS device in the network, such as the ENUM DNS_R device;

Step ④. According to the configuration information, ENUM DNS_R knows that the domain name can be resolved by ENUM DNS_A, so it requests domain name resolution from ENUM DNS_A;

Step ⑤, ENUM DNS_A returns the resource record corresponding to the domain name to ENUM DNS_R;

Step 6. ENUM DNS_R returns the resource record corresponding to the domain name to ENUM DNS_B;

Step 7. ENUM DNS_B returns the resource record corresponding to the domain name to SGSN_B;

Step 8. SGSN_B resolves the IP address of the attribution GGSN_A corresponding to the APN:xxxx from the resource record, and initiates a service request to GGSN_A;

Step 9: GGSN_A connects the user to the corresponding home packet data network PDN_A according to the APN, realizing the process of the mobile terminal accessing the home packet data network in the case of roaming in different places.

The foregoing embodiments are described by assuming that the mobile terminal carries a specific APN. When the mobile terminal carries an APN wildcard "*", the SGSN determines a specific APN according to standard protocols. It will not be described in detail here.

It can be seen that the above embodiment achieves the purpose of roaming to access the home packet data network, so that the terminal user can still perform the same packet data service as the home location when roaming.

The above implementation process is explained by using the recursive domain name resolution method to make the SGSN obtain the resource record of the domain name corresponding to the mobile terminal identifier as an example, but the embodiments of the present invention are not limited to the recursive domain name resolution method, and the ENUM DNS standard definition can also be used. Other ways to perform domain name resolution to achieve the same effect. For example, domain name resolution can be performed in a redirection manner. For example, when the SGSN requests a certain ENUM DNS device to resolve the domain name corresponding to the mobile terminal identifier, if there is no configuration information for the domain name in the ENUM DNS device, the ENUM DNS The device will inform the SGSN which ENUM DNS device can resolve the domain name, and then the SGSN will request the ENUM DNS device to resolve the domain name.

In the above-mentioned embodiment, the domain name information of MS_A is not configured in ENUM DNS_B, but the domain name information of MS_A is obtained by requesting the upper-level ENUM DNS device for illustration, so that it can only be configured in the ENUM DNS device in a certain area The corresponding relationship between all mobile terminal identifiers in this area and their attribution GGSN, thereby greatly reducing the amount of data configuration. Of course, if all ENUMDNS devices are configured with the corresponding relationship between all mobile terminal IDs in the entire network and the attribution GGSN, then when the ENUM DNS device receives the request from the SGSN device, it can directly resolve the domain name corresponding to the mobile terminal ID of MS_A. In this way, the purpose of roaming the mobile terminal to access the home packet data network can also be achieved, but with this method, the amount of data configuration is relatively large.

During the implementation of the solution, when there is a direct correspondence between the number segment identified by the mobile terminal and the home area, the mobile terminal in the specific number segment can correspond to the GGSN of its home location. Therefore, it is usually not necessary for each ENUM DNS device to The mobile terminal configures the resource record of the attribution GGSN corresponding to its domain name, but configures the resource record of the corresponding domain name for each number segment, which will greatly reduce the amount of data configuration in the ENUM DNS device.

When there is no direct correspondence between the number segment of the mobile terminal ID and the home area, it is necessary to configure the resource record of the domain name corresponding to each mobile terminal ID on the local network in the ENUMDNS device to realize the corresponding relationship between the mobile terminal, the APN and the home GGSN . Therefore, the embodiments of the present invention can solve the problem of accessing the home packet data network under the condition that MNP needs to be implemented.

During specific implementation, the resource records of the domain names corresponding to all mobile terminal identifiers in the entire network can be stored in an ENUM DNS, so that all ENUM DNS domain name resolution requests point to this ENUM DNS. It is also possible to save resource records of domain names corresponding to all mobile terminal identifiers in the entire network in the ENUM DNS device in each area, so that the ENUM DNS device in each area can directly resolve the ENUM domain name resolution request of SGSN. It is also possible to distribute and store the resource records of the domain name corresponding to the mobile terminal identifier in the network in ENUM DNS devices in each area, and find the resource record of the domain name corresponding to the mobile terminal identifier through the standard ENUM DNS domain name resolution process.

In the above embodiment, the corresponding relationship between the APN and the GGSN IP address is configured in the resource record, and the corresponding GGSN IP address is found as an example for illustration. When the corresponding relationship between the APN and the GGSN domain name is configured in the resource record, it is necessary to resolve After arriving at the GGSN domain name corresponding to the APN, the IP address of the GGSN must be resolved through a standard DNS process.

In the above-mentioned embodiment, the general APN is used to access the home GGSN as an example. The method and system of the present invention are still applicable to the dedicated APN. It is only necessary to add the home GGSN IP address or domain name corresponding to the dedicated APN domain name to in the resource record. The specific implementation process is similar to the description in the above embodiments, and will not be described in detail here.

In the above embodiment, the ENUM DNS device can be configured with the function of a standard DNS device at the same time, so as to be compatible with the domain name resolution process of the standard DNS device.

The second embodiment provided by the present invention is a system for accessing the home packet data network. Its structure is shown in FIG.

Before implementing the second embodiment, the ENUM DNS_B device at the visited location is configured with a resource record of the domain name corresponding to the mobile terminal identifier, and the resource record includes the correspondence between the APN and the IP address of the GGSN_A at the mobile terminal's home location, Or it is the corresponding relationship between the APN and the domain name of the GGSN_A where the mobile terminal belongs.

After the mobile terminal roams to the visited place, it requests the packet data service corresponding to the APN from the SGSN_B device of the visited place network.

The SGSN_B device of the foreign network constructs the domain name corresponding to the mobile terminal identifier, and requests the ENUM DNS_B device of the foreign network to resolve the domain name.

After receiving the request from the SGSN_B device, the ENUM DNS_B device of the visited network finds that it has configured a resource record of the domain name corresponding to the mobile terminal identifier, and returns the resource record directly to the visited SGSN_B device.

After the SGSN device at the visited location obtains the IP address or domain name of the GGSN_A device at the home location corresponding to the mobile terminal identifier, it initiates a service request to the GGSN_A device at the home location according to the IP address or domain name.

The GGSN_A device at the home site connects the mobile terminal's request to the packet data network at the home site corresponding to the APN requested by the mobile terminal.

The third embodiment provided by the present invention is another system for accessing the home packet data network. Its structure is shown in FIG. ; and the upper-level ENUM DNS equipment of the ENUM DNS_B equipment of the visiting place and the ENUM DNS_A equipment of the attribution place.

Before implementing this embodiment, it is assumed that the ENUM DNS_A device is configured with a resource record of the domain name corresponding to the mobile terminal identifier, and the resource record includes the correspondence between the APN and the IP address of the GGSN_A where the mobile terminal belongs, or the relationship between the APN and the mobile terminal’s home The corresponding relationship of the domain name of the local GGSN_A.

After the mobile terminal roams to the visited place, it requests the packet data service corresponding to the APN from the SGSN_B device of the visited place network.

The SGSN_B device of the foreign network constructs the domain name corresponding to the mobile terminal identifier, and requests the ENUM DNS_B device of the foreign country for corresponding domain name resolution.

When the ENUM DNS_B device at the visited location receives the request from the SGSN_B device and finds that it has not configured the resource record of the domain name corresponding to the mobile terminal identifier, it will pass through the upper-level ENUM DNS device in the network, according to the standard ENUM DNS The device domain name resolution process resolves the resource record of the domain name corresponding to the mobile terminal identifier, that is, the ENUM DNS_R knows that the ENUMDNS_A device is configured with the resource record of the domain name corresponding to the mobile terminal identifier according to the configuration, and then requests the corresponding domain name resolution from the ENUMDNS_A device ; The ENUM DNS_A device returns the resource record corresponding to the domain name according to the configuration information therein. The specific implementation process is the same as the relevant description in the first embodiment provided by the present invention, and will not be described in detail here.

After the SGSN_B device at the visited location obtains the IP address or domain name of the GGSN_A device at the home location corresponding to the mobile terminal identifier, it initiates a service request to the GGSN_A device at the home location according to the IP address or domain name.

The GGSN_A device at the home site responds to the mobile terminal's request to access the packet data network at the home site corresponding to the APN.

The fourth embodiment provided by the present invention is an SGSN device, the structure of which is shown in FIG. 6 , including: a processing unit and a requesting unit. The processing unit includes a conversion subunit, an acquisition subunit and an analysis subunit.

The processing unit interacts with the ENUM DNS device to obtain the IP address or domain name of the home GGSN device corresponding to the mobile terminal identifier. During specific processing, the corresponding domain name is constructed by the conversion subunit according to the mobile terminal identification, and then the ENUM DNS device is requested to resolve the domain name by the acquisition subunit, and the returned domain name is obtained by the ENUM DNS device Resource record; then, according to the requested resource record, the parsing subunit parses out the IP address or domain name of the home GGSN corresponding to the APN requested by the mobile terminal.

The requesting unit initiates a service request to the home GGSN device according to the IP address or domain name acquired by the obtaining unit.

It can be seen from the specific implementation scheme provided by the above-mentioned embodiments of the present invention that when the mobile terminal roams to the visited place and uses APN to initiate a request, the SGSN device in the visited place interacts with the ENUM DNS device to obtain the mobile terminal IP address or domain name of the GGSN at the home location; and initiate a service request to the GGSN at the home location according to the IP address or domain name, thereby accessing the packet data network at the corresponding home location. Therefore, in the case of roaming, the mobile terminal can access the packet data network at the home location even if the general APN is adopted. In addition, when the MNP is implemented on the entire network, the mobile terminal can access the home packet data network. And the introduction of ENUM DNS equipment can be compatible with the original standard domain name resolution mechanism.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (11)

1. A method for accessing a home packet data network, characterized in that, comprising: After receiving the service request sent by the mobile terminal roaming to the visited place using the access point name APN, the service general packet wireless service support node SGSN equipment of the visited place interacts with the electronic encoding domain name system ENUM DNS device to obtain the mobile terminal identification correspondence The resource record of the domain name, and according to the resource record analysis to obtain the IP address or the domain name of the home gateway general packet radio service support node GGSN corresponding to the mobile terminal identifier; and according to the IP address or domain name to the home GGSN initiates a service request; The GGSN at the home location sends the mobile terminal's request to access the packet data network at the home location corresponding to the APN. 2. The method of claim 1, further comprising: Configure the resource record of the domain name corresponding to the mobile terminal identifier in the ENUM DNS device, and the resource record includes the correspondence between the APN and the IP address of the GGSN at which the mobile terminal belongs, or the correspondence between the APN and the domain name of the GGSN at which the mobile terminal belongs. 3. The method according to claim 1 or 2, wherein the visited SGSN device interacts with the ENUM DNS device to obtain the home gateway general packet radio service support node (GGSN) corresponding to the mobile terminal identifier IP address or domain name process, specifically including: The SGSN device at the visited site constructs a corresponding domain name according to the mobile terminal identifier, and requests domain name resolution to the ENUM DNS device; The ENUM DNS device returns the resource record corresponding to the domain name to the SGSN device at the visited location according to the configuration information therein; The SGSN device in the visited location resolves the IP address or domain name of the GGSN in the home location corresponding to the APN requested by the mobile terminal according to the resource record. 4. The method according to claim 3, wherein the ENUM DNS device returns the resource record corresponding to the domain name to the SGSN device at the visited site according to the configuration information therein, specifically comprising: When the resource record of the domain name corresponding to the mobile terminal identifier is configured in the ENUM DNS device, the resource record corresponding to the domain name is directly returned to the SGSN device at the visited location. 5. The method according to claim 3, wherein the ENUM DNS device returns the resource record corresponding to the domain name to the SGSN device at the visited site according to the configuration information therein, specifically comprising: When the resource record of the domain name corresponding to the mobile terminal identification is not configured in the ENUM DNS device, the domain name corresponding to the mobile terminal identification is resolved according to the standard ENUM DNS domain name resolution process through the upper-level ENUM DNS device in the network , and then return the resource record corresponding to the domain name to the SGSN device in the visited location. 6. A system for accessing the attribution packet data network, characterized in that, comprising: Visited SGSN equipment, home GGSN equipment, and ENUM DNS equipment; The visited SGSN device is used to receive the service request sent by the mobile terminal roaming to the visited place using APN, interact with the ENUM DNS device to obtain the resource record of the domain name corresponding to the mobile terminal identifier, and according to the resource record Analyzing and obtaining the IP address or domain name of the home GGSN corresponding to the mobile terminal identifier; and initiating a service request to the home GGSN device according to the IP address or domain name; The home GGSN equipment accesses the mobile terminal's request to the home packet data network corresponding to the APN. 7. The system according to claim 6, wherein the visited SGSN device is used for: Construct the corresponding domain name according to the mobile terminal identification, and request the resolution of the domain name to the ENUM DNS device, obtain the resource record corresponding to the domain name; and resolve the requested resource record of the mobile terminal according to the requested resource record The IP address or domain name of the attribution GGSN corresponding to the APN. 8. The system according to claim 6, wherein the ENUM DNS device is used for: When the resource record of the domain name corresponding to the mobile terminal identifier is configured in the ENUM DNS device, the resource record corresponding to the domain name is directly returned to the SGSN device in the visited place; the resource record includes APN and mobile terminal The correspondence between the IP address of the home GGSN, or the correspondence between the APN and the domain name of the GGSN at the home of the mobile terminal. 9. The system according to claim 6, wherein the ENUM DNS device is used for: When the resource record of the domain name corresponding to the mobile terminal identification is not configured in the ENUM DNS device, the domain name corresponding to the mobile terminal identification is resolved according to the standard ENUM DNS domain name resolution process through the upper-level ENUM DNS device in the network and return to the visited SGSN device; the resource record includes the correspondence between the APN and the IP address of the mobile terminal's home GGSN, or the correspondence between the APN and the mobile terminal's home GGSN domain name. 10. A service general packet radio service support node device, characterized in that it comprises: The processing unit is configured to obtain the resource record of the domain name corresponding to the mobile terminal identifier by interacting with the ENUM DNS device after receiving the service request sent by the mobile terminal roaming to the visited place using the APN, and obtain the resource record by parsing the resource record. The IP address or domain name of the attribution GGSN corresponding to the mobile terminal identifier; The requesting unit is configured to initiate a service request to the home GGSN according to the IP address or domain name. 11. The device according to claim 10, wherein the processing unit comprises: A converting subunit, configured to convert the mobile terminal identifier into a corresponding domain name; The obtaining subunit is used to obtain the resource record of the domain name corresponding to the mobile terminal identifier by interacting with the ENUM DNS device; The parsing subunit is configured to, according to the resource record, parse out the IP address or domain name of the GGSN device at which the service corresponding to the APN requested by the mobile terminal belongs.

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