WO2008151554A1

WO2008151554A1 - Method, system and apparatus for determining the route in cdma network

Info

Publication number: WO2008151554A1
Application number: PCT/CN2008/071210
Authority: WO
Inventors: Sihai Ye; Tao Hui; Youjun Chen
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2007-06-08
Filing date: 2008-06-05
Publication date: 2008-12-18
Also published as: CN101321379A

Abstract

A method, system and apparatus for determinating the route in CDMA network are provided. The method comprises: after the message distributing device has received the initial layer-3 message initiated by a user, selecting a CN node on the basis of the IMSI carried in the initial layer 3 message and the correspondence of the IMSIs stored in a data backup center to the CN nodes, and routing the initial layer 3 message to the selected CN node. Further, the present invention provides a system for determining the route, a data backup center and a message distributing device. With the solution of the present invention, it is possible to reduce the number of the inter-office location updating.

Description

Method, system and device for determining route in CDMA network

Technical field

The present invention relates to mobile communication technologies, and in particular, to a method, system and apparatus for determining a route in a Code Division Multiple Access (CDMA) Code A Multiple Access (A-Flex) network. Background technique

In the traditional CDMA network architecture, the 1 :N (N is a natural number) connection between the Mobile Switch Center (MSC) and the Base Station Controller (BSC) controls the flexibility of the networking. For example, if an MSC is down for upgrade maintenance or failure, all BSCs connected to the MSC will be disabled, and all users within the BSC coverage will not be able to communicate with the circuit.

In order to solve the above problem, the A-Flex networking mode is introduced in CDMA. One MSC can connect to multiple BSCs, and one BSC can also connect multiple MSCs. These MSCs form an MSC pool for one BSC connected, and the user does not need to change the serving MSC when moving in the pool area. In the existing CDMA A-Flex technology, user-initiated initial layer 3 messages, such as service request messages, location update request messages, paging response messages, etc., are generally based on the user's international mobile station identity (IMSI, International Mobile). Station Identity) to select a route. The specific operation process is as follows: The corresponding relationship between the IMSI and the MSC is configured on the BSC. After receiving the initial layer 3 message initiated by the user, the BSC selects the corresponding MSC according to the IMSI carried in the message of the initial layer 3 and the configured correspondence. Message distribution.

For example, the operation management system (0&M) can configure the routing information shown in Table 1 on each BSC in the pool. After receiving the initial layer 3 message initiated by the mobile station (MS, Mobile Station), the BSC extracts the IMSI, calculates the value of the IMSI/10 mod 1000, and then determines the destination MSC of the initial layer 3 message according to the value lookup table 1. Table 1

For the case of load redistribution or load migration, you can modify the routing information configured on the BSC. For example, when the user on the MSC1 corresponding to the IMSI/10 mod 1000 = 123 segment is migrated to the MSC2 due to heavy load or other reasons, the routing information configured on all BSCs in the pool can be synchronously modified to Table 2. The form of the show. Thereafter, the user corresponding to the IMSI/10 mod 1000 = 123 segment will be routed to the MSC 2 regardless of which BSC in the pool initiates the initial layer 3 message. Table 2

In addition to the above-mentioned routing information on all BSCs in the pool in the case of load redistribution or load migration, each BSC in the pool area can modify its own saved routing information according to changes in network status in real time. For example, if BSC1 finds that its link with MSC3 is faulty, BSC1 can migrate the user on MSC3 to other reachable MSCs in the pool, such as MSC1, and route the routing information saved by BSC1 to the IMSI number of MSC3. Segment user route Modified to MSC1. At this time, if the MS of the IMSI number segment corresponding to the original MSC3 initiates an initial layer 3 message to the BSC1, the BSC1 will route the initial layer 3 message to the MSC1 by viewing the routing information. However, since the routing information in other BSCs does not change at this time, when the MS1 roams to other BSCs in the pool, the other BSCs still route the messages of the MS1 to the MSC3. At this time, the MSC3 needs to perform an inter-office location update to the Home Location Register (HLR).

It can be seen that the method for determining the route in the existing CDMA A-Flex network is likely to cause a change in the user service MSC, resulting in an increase in the number of inter-office location updates of users roaming in the pool area. Summary of the invention

The present invention provides a method, system and apparatus for determining a route in a CDMA network to reduce inter-office location updates.

A method for determining a route in a CDMA network provided by an embodiment of the present invention is as follows:

Receiving an initial service message initiated by the user;

Sending the international mobile station identity IMSI carried in the initial service message to the data backup center, and querying the data backup center for the core network CN node corresponding to the IMSI;

Receiving information of the CN node fed back by the data backup center, and transmitting the initial service message to the CN node.

The method for determining a route in another CDMA network according to the embodiment of the present invention is as follows: receiving a request for querying a CN node sent by a data distribution device, where the request includes an IMSI, and the IMSI is received by the data distribution device In the initial business message;

Selecting a CN node according to the received IMSI and the corresponding relationship between the IMSI and the CN node saved by itself, and returning information of the selected CN node to the message distribution device;

The information of the CN node is used by the message distribution device to send the initial service message to the selected CN node.

A system for determining a route in a CDMA network according to an embodiment of the present invention includes at least one message distribution device and at least one CN node, and further includes a data backup center, where The message distribution device is configured to receive an initial service message initiated by the user, send the IMSI carried in the initial service message to the data backup center, and according to the information of the CN node fed back by the data backup center, Sending an initial service message to the selected CN node;

The data backup center is configured to save a correspondence between the IMSI and the CN node of the user, and when receiving the IMSI sent by the message distribution device, according to the received IMSI, and the corresponding IMSI and CN node corresponding to the CN node The relationship selects a CN node and returns information of the selected CN node to the message distribution device.

In addition, the embodiment of the present invention further provides a data backup center, including: a data saving unit and a node determining unit, where

a data saving unit, configured to save a correspondence between the user's IMSI and the CN node;

a node determining unit, configured to receive an IMSI from the message distribution device, select a CN node according to the received IMSI, and a correspondence between the IMSI and the CN node saved in the data saving unit, and return information of the selected CN node to The message distribution device.

The embodiment of the present invention further provides a message distribution device, including: a message receiving unit and a message distribution unit, where

a message receiving unit, configured to receive an initial service message initiated by the user, and forward the received initial service message to the message distribution unit;

The message distribution unit is configured to send the IMSI carried in the received initial service message to the data backup center, and receive the information of the CN node returned by the data backup center, and send the received initial service message to the CN node.

Therefore, in the embodiment of the present invention, after receiving the initial service message initiated by the user, all the message distribution devices in the pool determine the route of the user message according to the information held in the data backup center, instead of according to the The saved information is used to determine the routing of user messages. Therefore, the occurrence of changes in the user service CN node caused by the inconsistency of the routing information maintained by each message distribution device in the prior art is avoided, and the number of inter-office location updates is reduced. DRAWINGS

1 is a schematic diagram showing the connection relationship between an MSC and a BSC in a conventional CDMA network architecture in the prior art;

2 is a schematic diagram showing a connection relationship between an MSC and a BSC in a CDMA A-Flex network architecture in the prior art;

3 is a schematic diagram of a CDMA A-Flex network architecture for adding a data backup center according to an embodiment of the present invention;

4 is a flowchart of a method for determining a route in a CDMA A-Flex network according to an embodiment of the present invention; FIG. 5 is a schematic diagram of another CDMA A-Flex network architecture for adding a data backup center according to an embodiment of the present invention;

FIG. 6 is a schematic structural diagram of a system for determining a route in a CDMA A-Flex network according to an embodiment of the present invention; FIG. 7 is a schematic structural diagram of a data backup center and a message distribution device according to an embodiment of the present invention; FIG. 8 is a node determining unit according to an embodiment of the present invention; Schematic diagram of the structure;

FIG. 9 is a schematic diagram of a CDMA A-Flex network architecture using a primary and backup data backup center according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

As can be seen from the background art, the connection relationship between the MSC 100 and the BSC 200 in the conventional CDMA network architecture is as shown in FIG. 1. One MSC 100 can be connected to multiple BSCs 200, and one BSC 200 can only be connected to one MSC 100. In the prior art CDMA A-Flex network architecture, the connection relationship between the MSC 100 and the BSC 200 is as shown in FIG. 2. In FIG. 2, not only one MSC 100 can be connected to multiple BSCs 200, but also one BSC 200 can also be connected to multiple MSCs 100. A BSC 200 is connected to form an MSC pool, and the user does not need to change the serving MSC when moving in the pool area. However, the method for determining the message routing according to the routing information configured on the BSC in the existing CDMA A-Flex network is likely to cause a change in the user service MSC, resulting in an increase in the number of user location updates. In order to overcome the above problem, an embodiment of the present invention provides a method for determining a route in a CDMA A-Flex network, including: setting a data backup center, and storing a correspondence between a user IMSI and an MSC in a data backup center; The initial service message, for example, after receiving the initial layer 3 message, selecting an MSC according to the IMSI carried in the initial layer 3 message and the correspondence between the IMSI and the MSC saved in the data backup center, and then the BSC will receive the initial layer 3 The message is routed to the selected MSC.

That is to say, the correspondence between the IMSI and the MSC is not saved on the BSC, but the correspondence between the IMSI and the MSC is saved in the added data backup center. After receiving all the initial Layer 3 messages initiated by the user, all the BSCs in the pool determine the route of the user message based on the information stored in the data backup center. Therefore, the occurrence of changes in the user service MSC caused by the inconsistent routing information maintained by each BSC in the prior art is avoided, and the number of inter-office location updates is reduced.

The data backup center can be either a stand-alone physical device or a functional component in the MSC. In addition to the backup user IMSI and MSC correspondence, the data backup center can also be used to back up the user's location area identifier (LAI) and switch status. Moreover, the data backup center is fully interconnected with the MSC. When the user data in the MSC changes, the MSC needs to notify the data backup center to update the information it holds. For example, when a new user in the MSC registers successfully or a user is deleted, the MSC informs the data backup center of the user information that is successfully registered or deleted; after receiving the data backup center, the IMSI of the user who successfully registered is saved and the user Corresponding relationship of the home MSC, or deleting the correspondence between the IMSI of the deleted user and the home MSC of the user. In addition, the MSC can also notify the data backup center of the information that the user LAI changes and the user's power on/off information, and the data backup center receives the corresponding data after receiving it.

In order to save storage resources, the data backup center can also set a separate timer for each user data. If no operation is performed on the user data corresponding to the timer within a certain timer protection time, that is, within the set time of the timer, the user data is deleted after the timer expires.

FIG. 3 is a schematic diagram of a CDMA A-Flex network architecture for adding a data backup center according to an embodiment of the present invention. The following describes the routing in the CDMA A-Flex network in the embodiment of the present invention with reference to FIG. The method is described in detail. The method flow is shown in FIG. 4, and mainly includes the following steps: Step 401: The MS initiates an initial layer 3 message to the BSC;

Step 402: After receiving the initial layer 3 message initiated by the MS, the BSC sends the IMSI carried in the initial layer 3 message to the data backup center.

Step 403: The data backup center selects an MSC according to the received IMSI and the corresponding relationship between the IMSI and the MSC saved by itself, and returns the selected MSC information to the BSC. Step 404: The BSC receives the MSC information returned by the data backup center. After that, the received initial layer 3 message is routed to the MSC.

The specific process of step 403 includes:

After receiving the IMSI sent by the BSC, the data backup center searches for the corresponding relationship between the IMSI and the MSC stored by the BSC, and determines whether there is an MSC corresponding to the received IMSI. If there is a corresponding MSC, and the signaling point of the MSC The data backup center returns the MSC information to the BSC; if there is a corresponding MSC, but the signaling point of the MSC is unreachable, or it is determined that there is no corresponding MSC, the data backup center selects a signaling from the pool. The point-accessible MSC sends the selected MSC information to the BSC, and saves the correspondence between the received IMSI and the selected MSC. After that, the data backup center performs routing selection according to the newly saved correspondence.

The policy of the data backup center selecting a MSC that is reachable by a signaling point from the pool includes but is not limited to the following: selecting a MSC that is reachable by a signaling point from the pool according to the principle of round robin; or randomly selecting a letter from the pool MSCs with reachable points; or, select an MSC that is reachable by the lightest signaling point from the pool.

The routing determination methods described above are all described for the 7-load and control CDMA A-Flex network architecture. It should be noted that the present invention is equally applicable to a CDMA A-Flex network architecture in which bearer and control are separated. The separation between bearer and control means that the MSC adopts a softswitch architecture, including a mobile switching center server (MSC Server) and a media gateway (MGW). In the CDMA A-Flex network architecture with separate control and control, the A-Flex function can be implemented either on the BSC or on the MGW.

Different from Figure 3, in the CDMA A-Flex network architecture with separate bearer and control, The correspondence between the IMSI and the MSC Server is stored in the data backup center. If the A-Flex function is implemented on the BSC, the implementation process of the entire determined route is basically the same as that in FIG. 4, the difference is: after receiving the initial layer 3 message sent by the BSC and carrying the IMSI, the data backup center receives the The IMSI and the corresponding relationship between the IMSI and the MSC Server are selected, and an MSC Server is selected, and the selected MSC Server information is returned to the BSC; after the BSC receives the MSC Server information returned by the data backup center, the initial layer will be received. 3 The message is routed to the MSC Server. Referring to another CDMA A-Flex network architecture shown in FIG. 5, if the A-Flex function is implemented on the MGW, the action of querying the data backup center for the user's home MSC Server information is performed by the MGW. Upon completion, the data backup center needs to return the selected MSC Server information to the MGW, and then the MGW then routes the user initial layer 3 message to the MSC Server specified in the MSC Server information returned by the data backup center. The process of how to select the MSC Server in the data backup center is similar to the step 403, and details are not described herein.

In this document, for convenience of description, the BSC and the MGW may be collectively referred to as a message distribution device; the MSC and the MSC Server are collectively referred to as a core network (CN, Core Network) node.

Accordingly, embodiments of the present invention also provide a system for determining a route in a CDMA A-Flex network. The system structure is shown in FIG. 6, and mainly includes: a data backup center 300, at least one message distribution device 210, and at least one CN node 500. among them,

The data backup center 300 is configured to store a correspondence between the user IMSI and the CN node 500. The message distribution device 210 is configured to receive an initial service message initiated by the user, for example, receive an initial layer 3 message, according to the IMSI carried in the initial layer 3 message, And the corresponding relationship between the IMSI and the CN node 500 held in the data backup center 300 selects a CN node, and routes the initial layer 3 message to the selected CN node 500.

Specifically, the message distribution device 210 is configured to receive the initial layer 3 message initiated by the user, and then send the IMSI carried in the initial layer 3 message to the data backup center 300. The data backup center 300 is configured to save the correspondence between the user IMSI and the CN node 500. When receiving the IMSI sent by the message distribution device 210, according to the received IMSI, and the pair of the IMSI and the CN node 500 saved by itself. A CN node 500 is selected for the relationship, and the selected CN node information, the information of the CN node to be selected, is returned to the message distribution device 210 to instruct the message distribution device 210 to route the initial layer 3 message to the selected CN node 500. .

Referring to FIG. 7, the data backup center 300 may specifically include: a data saving unit 320 and a node determining unit 310. The message distributing device 210 may specifically include: a message receiving unit 211 and a message distributing unit 212. among them,

The data saving unit 320 is configured to save a correspondence between the user IMSI and the CN node 500. The node determining unit 310 is configured to receive the IMSI from the message distribution device 210, according to the received IMSI and the IMSI and the CN saved in the data saving unit 320. Corresponding relationship of the node 500 selects a CN node, and returns the selected CN node information to the message distribution device 210;

The message receiving unit 211 is configured to receive the initial layer 3 message initiated by the user, and forward the received initial layer 3 message to the message distributing unit 212;

The message distribution unit 212 is configured to send the IMSI carried in the received initial layer 3 message to the data backup center 300, and receive the CN node information returned by the data backup center 300, and route the received initial layer 3 message to the CN node.

Referring to FIG. 8, the node determining unit 310 may include: an information transceiving unit 311 and a node selecting unit 312. The information transceiving unit 311 is configured to receive the IMSI from the message distribution device 210, forward the received IMSI to the node selection unit 312, and receive the CN node information returned by the node selection unit 312, and send the received CN node information. Giving a message distribution device 210;

The node selection unit 312 is configured to determine whether there is a CN node corresponding to the received IMSI by searching the correspondence between the IMSI and the CN node saved in the data holding unit 320, if there is a corresponding CN node and the signaling point of the CN node If the information is reachable, the CN node information is returned to the information transceiver unit 212; if there is a corresponding CN node but the signaling point of the CN node is unreachable, or it is determined that there is no corresponding CN node, then a signaling is selected from the pool. The point-accessible CN node returns the selected CN node information to the information transceiving unit 212, and stores the correspondence between the received IMSI and the selected CN node in the data holding unit 320.

The CN node may be further used to pass the information that the user has successfully registered or the user is deleted. The data backup center may further include: a data update unit, configured to update the user data saved in the data storage unit after receiving the notification of the CN node.

The data updating unit may be further configured to separately set a timer for each user data saved in the data saving unit, and if the user data corresponding to the timer is not performed within the timer protection time, that is, within the timer setting time, In any operation, the user data saved in the data holding unit is deleted after the timer expires.

The data backup center can be an independent physical device or a functional component in the CN node. When the CDMA A-Flex network adopts a network architecture with integrated control and control, the CN node is the MSC and the message distribution device is the BSC. When the CDMA A-Flex network adopts the network architecture with separate bearer and control, the CN node is the MSC Server. The message distribution device is a BSC or an MGW.

It should be noted that although only one data backup center is shown in FIG. 3, FIG. 5 and FIG. 6, in actual application, more than one data backup center may be set according to actual needs. Multiple data backup centers can work either in active/standby mode or in mutual help mode. Figure 9 shows a schematic diagram of a CDMA A-Flex network architecture using a primary and backup data backup center. The data of the primary data backup center 350 and the standby data backup center 360 need to be synchronized.

It can be seen that, in the embodiment of the present invention, all the message distribution devices in the pool determine the route of the user message according to the information held in the data backup center, and can avoid the inconsistency of the routing information maintained by each message distribution device in the prior art. The resulting user service CN node changes, thereby reducing the number of interoffice location updates.

The above-mentioned objects, technical solutions, and advantageous effects of the present invention are further described in detail. It is to be understood that the above description is not intended to limit the present invention, and what is made within the spirit and principles of the present invention Any modifications, equivalent substitutions, improvements, etc., are intended to be included within the scope of the present invention.

Claims

Rights request

A code division multiple access method for determining a route in a CDMA network, comprising: receiving an initial service message initiated by a user;

2. The method according to claim 1, wherein: the initial service message is specifically an initial layer 3 message.

3. A method for determining a route in a CDMA network, the method comprising:

Receiving, by the data distribution device, a request for querying a CN node, where the request includes an IMSI, where the IMSI is carried in an initial service message received by the data distribution device;

4. The method according to claim 3, wherein: the initial service message is specifically an initial layer 3 message.

The method according to claim 3, wherein a CN node is selected according to the received IMSI and the corresponding relationship between the IMSI and the CN node saved by itself, and the information of the selected CN node is returned to The message distribution device includes:

Finding a correspondence between the IMSI and the CN node that is saved by itself, determining whether there is a CN node corresponding to the received IMSI, and determining that a corresponding CN node exists and the signaling point of the CN node is reachable, The information of the CN node is sent to the message distribution device.

The method according to claim 3, wherein a CN node is selected according to the received IMSI and a corresponding relationship between the IMSI and the CN node saved by itself, and the selected CN is selected. Returning information of the node to the message distribution device includes:

Finding the correspondence between the IMSI and the CN node saved by itself, determining whether there is a CN node corresponding to the received IMSI, and determining that there is a corresponding CN node but the signaling point of the CN node is unreachable, or determining that When there is a corresponding CN node, a CN node that is reachable by a signaling point is selected from the pool, information of the selected CN node is sent to the message distribution device, and the received IMSI and the selected one are saved. Correspondence relationship of CN nodes.

The method according to claim 6, wherein the selecting a CN node that is reachable from a pool by a signaling point comprises:

Select a CN node that is reachable by a signaling point from the pool according to the principle of rotation;

Or randomly selecting a CN node that is reachable by a signaling point from the pool;

Or, select a CN node that is reachable by the lightest signaling point from the pool.

The method according to any one of claims 3 to 7, wherein the method further comprises: receiving information that the user registration succeeded by the CN node or the user is deleted, and receiving the notification from the CN node to the user The saved user data is updated.

The method according to claim 3, wherein the method further comprises: setting a timer for each user data separately, if the user data corresponding to the timer is not performed within a timer setting time In any operation, the user data is deleted after the timer expires.

A system for determining a route in a CDMA network, comprising: at least one message distribution device and at least one CN node, further comprising: a data backup center, wherein

The message distribution device is configured to receive an initial service message initiated by the user, send the IMSI carried in the initial service message to the data backup center, and according to the information of the CN node fed back by the data backup center, Sending an initial service message to the selected CN node;

The system according to claim 10, wherein: the initial service message is specifically Initial layer 3 message.

12. The system of claim 10 wherein:

The data backup center includes: a data saving unit and a node determining unit, where

The data saving unit is configured to save a correspondence between the IMSI of the user and the CN node; the node determining unit is configured to receive the IMSI from the message distribution device, according to the received IMSI, and the IMSI saved in the data saving unit Corresponding relationship of the CN node selects a CN node, and returns information of the selected CN node to the message distribution device;

The message distribution device includes: a message receiving unit and a message distribution unit, where

The message receiving unit is configured to receive an initial service message initiated by the user, and forward the received initial service message to the message distribution unit;

The message distribution unit is configured to send the received IMSI carried in the initial service message to the data backup center, and receive information about a CN node returned by the data backup center, and the received An initial service message is sent to the selected CN node.

The system according to claim 12, wherein the node determining unit comprises: an information transceiving unit and a node selecting unit, wherein

The information transceiver unit is configured to receive an IMSI from the message distribution device, forward the received IMSI to the node selection unit, and receive information of the CN node returned by the node selection unit, and receive the received CN The information of the node is sent to the message distribution device;

The node selection unit is configured to search for a correspondence between the IMSI and the CN node saved in the data holding unit, determine whether there is a CN node corresponding to the received IMSI, and determine that a corresponding CN node exists and the CN When the signaling point of the node is reachable, the information of the CN node is returned to the information transceiver unit.

The information transceiver unit is configured to receive an IMSI from the message distribution device, forward the received IMSI to the node selection unit, and receive information of the CN node returned by the node selection unit, and receive the received CN The information of the node is sent to the message distribution device; The node selection unit is configured to search for a correspondence between the MSI and the CN node in the data unit, determine whether there is a CN node corresponding to the MSI of the ^^, and determine that the corresponding CN node exists but the CN When the signaling point of the node is unreachable, or when it is determined that the corresponding CN node does not exist, the CN node that is reachable is also selected, and the information of the selected CN node is returned to the information. ^ unit, and in the data ^ "unit ^" the corresponding relationship between the received MSI and the selected CN node.

The system according to any one of claims 10 to 14, wherein the CN node is further configured to notify the data backup center of information that the user is successfully registered or the user is deleted; the data backup center further The method includes: a data update unit, configured to update user data saved in the data saving unit after receiving the notification of the CN node.

The system according to claim 15, wherein the data update unit further performs no operation on the user data corresponding to the timer within a set time, and then deletes after the timer expires. The user data saved in the data saving unit.

17. A data backup center, comprising: a data saving unit and a node determining unit, wherein

The data holding unit is configured to save a correspondence between the IMSI of the user and the CN node, where the node determining unit is configured to receive the IMSI from the message distribution device, according to the received IMSI, and the data saving unit The correspondence between the IMSI and the CN node selects a CN node, and returns information of the selected CN node to the message distribution device.

The data backup center according to claim 17, wherein the node determining unit comprises: an information transceiving unit and a node selecting unit, where

The node selection unit is configured to search for a correspondence between the IMSI and the CN node saved in the data holding unit, determine whether there is a CN node corresponding to the received IMSI, and determine that a corresponding CN node exists and the CN When the signaling point of the node is reachable, the information of the CN node is returned to the information ^^ unit.

The data centering unit according to claim 17, wherein the node determining unit comprises: an information transceiving unit and a node selecting unit, wherein

The information transceiving unit is configured to receive an MSI from the message distribution device, forward the received MSI to the node selection unit, and receive the information of the CN node that the node selects a single return, and will receive the information Information of the CN node is sent to the message distribution device;

The node selection unit is configured to search for a correspondence between the MSI and the CN node in the data unit, determine whether there is a CN node corresponding to the MSI of the ^^, and determine that the corresponding CN node exists but the CN When the signaling point of the node is unreachable, or when it is determined that the corresponding CN node does not exist, the CN node that is reachable is also selected, and the node information of the selected CN is returned to the information. ^ unit, and in the data ^ "unit ^" the corresponding relationship between the received MSI and the selected CN node.

The data center according to any one of claims 17 to 19, wherein the data backup center further comprises: a data update unit, configured to successfully register the user sent by the CN node or the user is After the deleted information, the user data of the data ^"unit ^" is updated.

21. The data processing center according to claim 20, wherein the data updating unit is further configured to respectively set a timer for each user data saved in the data saving unit, if the timer is set within the time set by the timer. If the user data corresponding to the timer is not operable, the user data in the data unit is deleted after the timer expires.

22. A message distribution device, comprising: a message receiving unit and a message distribution unit, wherein

The message receiving unit is configured to receive an initial service message of the user, and forward the received initial service message to the message distribution unit;

The message distribution unit is configured to send the received MSI in the initial service message to the data backup center, and receive the information of the CN node returned by the data backup center, and the initial service of the ^^ The message is sent to the CN node.

The message distribution device according to claim 22, wherein: the initial service message is specifically an initial layer 3 message.