CN103731816B - A kind of user device address management method - Google Patents

Abstract

The present application discloses a user equipment address management method. For each user equipment that successfully performs the attachment process, the core network internally caches its address allocation information; the first user equipment initiates an attach request, and the core network Whether the address attribute is included in the subscription information determines the address allocation method of the first user equipment. If the address attribute is included, the first user equipment is assigned a static address according to the address attribute in the subscription information of the first user equipment. If the address attribute is not included Then perform dynamic address allocation to the first user equipment; during the dynamic address allocation process, the core network finds that the address allocation information corresponding to the first user equipment has been cached, and assigns the IP address in the address allocation information to the first user equipment . The present application can flexibly allocate dynamic addresses and static addresses for UEs without increasing signaling overhead and without relying on DHCP technology.

Description

A user equipment address management method

technical field

The present application relates to the technical field of mobile communication, and in particular to a user equipment address management method.

Background technique

The network architecture of the LTE wireless communication system mainly includes user equipment (UE, User Equipment), access network (E-UTRAN, Evolved Universal Terrestrial Radio Access Network), and core network (EPC, Evolved Packet Core). The UE has a unique International Mobile Subscriber Identity (IMSI, International MobileSubscriber Identity). E-UTRAN is composed of base stations (eNodeB, Evolved NodeB). The eNodeB interacts with the UE for signaling and user plane data through the air interface. The functions include receiving signaling and uplink data from the UE, and sending signaling responses and downlink data to UE. The EPC is presented as three interfaces externally, the S1-MME interface is the signaling interface between the EPC and eNodeB, the S1-U interface is the user plane interface between the EPC and the eNodeB, and the SGI interface is the Data Network).

LTE wireless communication services are generally initiated by the UE. After the UE is turned on, it first needs to initiate an attach process to register with the EPC to request services. During the attach process, the EPC is responsible for establishing a user plane bearer for the UE and assigning an IP address to the UE. The PDN network will use this IP The address identifies the corresponding UE for data communication. The data communication between the PDN network and the UE is divided into uplink and downlink. The uplink data sent by the UE to the PDN network is forwarded to the EPC S1-U interface through the eNodeB. The EPC resolves the target address and delivers the uplink data to the designated PDN server through the SGI interface. The downlink data sent by the PDN network to the UE enters the EPC SGI interface. The EPC parses the target address to match the online UE and the corresponding bearer and forwards the downlink data to the eNodeB from the S1-U interface, and then the eNodeB delivers it to the designated UE through the air interface.

When the PDN network performs downlink data services with a designated UE, it must first know the IP address of the UE, and the IP address of the UE is allocated by the EPC during the attach process. Every time a UE with the same IMSI attaches successfully, the address allocated by the EPC Changes may occur, which will bring great inconvenience to the PDN network for the downlink data service of the specified UE. Therefore, it is necessary to ensure that the same UE initiates the attach procedure EPC to allocate the same IP address for as long as possible.

UE address management solutions in the prior art mainly include:

Existing technology 1: Since the attach process is always initiated by the UE, the UE can carry the address cell allocated by the EPC during the last attach in the Attach Request (AttachRequest) message, and the EPC analyzes the message and allocates the address to the UE. If the UE is attaching for the first time, the attach request message may carry an information element to indicate the address to be allocated by the EPC; or not carry the information element, at this time the EPC will select an available address to allocate to the UE. In this way, multiple attachments of the UE can ensure that the EPC allocates the same address to it for a long period of time. According to the definition of the attachment request message structure given by the LTE standard, the address allocated by the UE for the last attachment can be included in the optional protocol configuration option (PCO, Protocol Configuration Options) of the PDN Connectivity Request (PDN Connectivity Request) message as an attachment request A part of the message is sent to the EPC together.

Existing technology 2: based on EPC implementation, after receiving the UE's attach request message, the EPC will first obtain the UE's subscription information according to the UE's IMSI before allocating an address for it, so it is possible to plan one for each IMSI— The corresponding fixed address is stored in the subscription information of the UE, so that the EPC can assign a specified fixed address to the UE according to the address plan. As long as the subscription information of the UE remains unchanged, the address allocated by the EPC when it initiates the attach process will also remain unchanged. If another address needs to be planned for the UE of a certain IMSI, the operation and maintenance personnel only need to update the fixed address value in the subscription information of the UE accordingly.

Existing technology 3: Introduce Dynamic Host Configuration Protocol (DHCP, Dynamic Host Configuration Protocol) technology, that is, add the role of DHCP server in the wireless communication network, and the DHCP server is responsible for assigning a static address or a dynamic address to each UE. The static address allows a specific UE to be assigned a fixed address every time it attaches. At the same time, the lease feature in DHCP allows a UE currently using a dynamic address to be assigned to it for multiple attachments during the lease period. The same address, and the lease can be renewed (renew) to continue using the address before the lease expires.

There is following defective in above prior art:

Existing technology - The solution of carrying the optional information element of the last address in the attach request message requires additional configuration for the UE, and also increases the air interface signaling overhead between the UE and the eNodeB. In prior art 2, address allocation is realized through one-to-one correspondence between UE subscription information planning and IMSI, which increases the burden of management of a large number of UE subscription information on operation and maintenance personnel, and also loses the flexibility of address allocation. The DHCP introduced in prior art 3 is a mature address allocation technology, which can better reduce the burden on operation and maintenance personnel to manage subscription information, and has more flexible static address and dynamic address allocation methods, and the UE does not need to increase the portability The overhead of the address cell increases the deployment and maintenance costs of the DHCP server, and since the DHCP server is invisible to the UE, the EPC needs to represent the UE to implement the role of the DHCP client to interact with the DHCP server, which increases the complexity of the implementation of the EPC device Spend. In addition, when the operation and maintenance personnel try to plan the dynamically allocated address of a certain UE as the static address of another UE, the configuration will fail due to address conflict. Usually, there are industry-specific requirements for planning a static address for a UE, and its communication service is also prioritized over other UEs that do not have a static address planned. DHCP cannot well solve this address conflict problem.

Contents of the invention

This application provides a user equipment address management method, which can flexibly allocate dynamic addresses and static addresses for UEs without increasing signaling overhead and relying on DHCP technology, and at the same time greatly reduces the number of operations and maintenance personnel managing a large number of UEs. The burden of contracting information.

In a method for managing user equipment addresses provided by an embodiment of the present application, for each user equipment that successfully performs the attach process, the core network internally caches its address allocation information; the method includes:

A. The first user equipment initiates an attach request, and the core network determines the address allocation method of the first user equipment according to whether the subscription information of the first user equipment contains address attributes. If the address attribute is included, step B is performed; if the address attribute is not included Then execute step C;

B. The core network assigns a static address to the first user equipment according to the address attribute in the subscription information of the first user equipment, and ends this process;

C. The core network performs dynamic address allocation to the first user equipment, and ends this process; during the dynamic address allocation process, if the core network finds that the address allocation information corresponding to the first user equipment has been cached, then the cached first user equipment The IP address in the corresponding address allocation information is allocated to the first user equipment.

Preferably, step B includes:

B1, the core network judges whether there is an online second user equipment whose address is the same as the address attribute value in the subscription information of the first user equipment, if so, execute step B2, otherwise execute step B5;

B2. The core network judges whether the address of the second user equipment is acquired statically or dynamically. If it is acquired statically, execute step B3, otherwise execute step B4;

B3. The core network rejects the attachment request of the first user equipment, and ends this process;

B4. The core network allocates the address corresponding to the address attribute value in the subscription information of the first user equipment to the first user equipment for use, notifies the second user equipment to reacquire a new IP address in a dynamic manner, and ends this process;

B5. The core network allocates the address corresponding to the address attribute value in the subscription information of the first user equipment to the first user equipment for use, and ends this process.

Preferably, step C includes:

C1. The core network judges whether the address allocation information corresponding to the first user equipment has been cached and the IP address in the address allocation information is not used by other online user equipment, if so, execute step C2, otherwise execute step C3;

C2. The core network allocates the IP address to the first user equipment, and ends this process;

C3. The core network selects a new available IP address according to a specific rule and assigns it to the first user equipment, and ends this process.

Preferably, the cache record of the address allocation information adopts the IMSI of the user equipment as a hash table storage method as a key value.

Preferably, the total number of buffered address allocation information is equal to the maximum capacity of the communication system.

Preferably, the core network marks each available address as three allocation situations, namely unused, used and recycled, the addresses in the used state are non-allocatable addresses, and the addresses in the unused state and recycled state are allocatable addresses ;

Step B1 includes: the core network judges whether there is an online second user equipment whose address is the same as the address attribute value in the subscription information of the first user equipment, if so, execute step B2, otherwise add or update the corresponding cache record of the first user equipment and execute Step B5;

Step B2 includes: the core network judges whether the address of the second user equipment is acquired statically or dynamically, and if it is statically acquired, then delete the cache record that may exist in the first user equipment and perform step B3, otherwise add or update the first user equipment Corresponding cache record and execute step B4;

Step C1 includes: the core network judges whether the address allocation information corresponding to the first user equipment has been cached, if it exists and the address corresponding to the address allocation information is allocable, then keep the cache record unchanged and execute C2; if it exists but the address If it cannot be allocated, delete the address value in the cache record and execute C3; if no corresponding cache record is found, add a cache record without address and execute C3.

Preferably, the method further includes: the first user equipment changes from the online state to the offline state, the core network changes the address status of the first user equipment from used to reclaimed during the process of deleting the session, and records the time when the address is reclaimed into the cache record, so that the offline user equipment in the cache record forms an offline cache record list in order according to the address recovery time.

Preferably, the core network performing dynamic address allocation or static address allocation to the first user equipment includes:

The core network records the original state of the address to be allocated;

The core network allocates a dynamic address or a static address to the first user equipment, and changes the status of the allocated address to used;

If the entire attaching process is successfully completed, the original state record is cleared, and once an attaching failure occurs after the session is created, the address is restored to the original state.

Preferably, step C3 includes:

C3-1. The core network checks the allocation of currently configured available addresses. If there is an unused address, go to step C3-2, otherwise go to step C3-3;

C3-2. The core network assigns an unused address to the first user equipment, and ends this process;

C3-3. The core network checks whether there is an address that can be allocated. If there is, go to step C3-4. Otherwise, the address allocation fails to end this process;

C3-4. The core network assigns the earliest reclaimed address to the first user equipment according to the time-ordered offline cache record list, and ends this process.

Preferably, step C3-2 and step C3-4 further include: the core network updates the cache record, and increases the address allocated for the first user equipment; and,

After the address allocation fails in step C3-3, it further includes: deleting the corresponding cache record of the first user equipment.

From the above technical solution, it can be seen that whether the subscription information of the user equipment that initiates the attach request contains address attributes determines whether to assign a static address or a dynamic address to the user equipment. This solution can efficiently complete dynamic address and address allocation without the participation of a DHCP server Assignment of static addresses. In the dynamic allocation mode, the UE does not need additional configuration and does not need to record the last used address to ensure that the UE with the same IMSI attaches multiple times within the address lifetime and the EPC allocates the same address. For a communication system with a reasonable plan, this lifetime is permanent. If the number of planned available addresses is small, the permanent lifetime of addresses used by UEs that are active in the near future can be protected to the greatest extent. At the same time, it also provides a reasonable solution to the conflict between dynamic addresses and static addresses, so as to meet the communication service requirements of planning static addresses in the industry.

Description of drawings

FIG. 1 is a schematic flow chart of a user equipment address management method provided by the present application;

Fig. 2 is a schematic diagram of the change relationship between the three states of available addresses;

Fig. 3 is a schematic diagram of the processing flow of address allocation in the process of updating location management;

Fig. 4 is a schematic diagram of dynamic allocation rules;

FIG. 5 is a schematic diagram of a processing flow for managing address allocation during session creation.

detailed description

This application provides a method for implementing user equipment address management without a DHCP server. For each user equipment that successfully performs the attach process, the core network internally caches its address allocation information; the method includes:

A. The first user equipment initiates an attach request, and the core network determines the address allocation method of the first user equipment according to whether the subscription information of the first user equipment contains address attributes. If the address attribute is included, step B is performed; if the address attribute is not included Then execute step C;

B. The core network assigns a static address to the first user equipment according to the address attribute in the subscription information of the first user equipment, and ends this process;

C. The core network performs dynamic address allocation to the first user equipment, and ends this process; during the dynamic address allocation process, if the core network finds that the address allocation information corresponding to the first user equipment has been cached, then the cached first user equipment The IP address in the corresponding address allocation information is allocated to the first user equipment.

Wherein, the address attribute contained in the subscription information of the first user equipment may conflict with addresses of other online user equipments, and a certain address conflict resolution mechanism may be adopted to avoid this problem. Adopt the principle of static allocation of high priority to further judge whether the addresses of other conflicting user equipments are obtained statically or dynamically. If it is the former, reject the attachment request of the first user equipment; if it is the latter, release the conflicting The online user equipment assigns the address to the first user equipment, and the released user equipment can obtain a new dynamic address by re-initiating attachment.

In order to make the technical principles, features and technical effects of the technical solution of the present application clearer, the technical solution of the present application will be described in detail below in conjunction with specific embodiments.

The process flow of the user equipment address management method provided in the embodiment of the present application is shown in Figure 1, including:

Step 101: The first user equipment initiates an attach request, and the core network determines the address allocation mode of the first user equipment according to whether the subscription information of the first user equipment includes address attributes, and if the address attributes are included, perform step 102 for static address allocation, Otherwise, step 107 is executed to perform dynamic address allocation.

Step 102: The core network judges whether there is an online second user equipment whose address is the same as the address attribute value in the subscription information of the first user equipment. If yes, execute step 103; otherwise, execute step 106.

Step 103: The core network judges whether the address of the second user equipment is acquired statically or dynamically. If it is acquired statically, execute step 104; otherwise, execute step 105.

Step 104: The core network rejects the attach request of the first user equipment, and ends this procedure.

Step 105: The core network allocates the address corresponding to the address attribute value in the subscription information of the first user equipment to the first user equipment, and notifies the second user equipment to reacquire a new IP address in a dynamic manner, so as to ensure all user equipment services of normal progress.

Step 106: The core network allocates the address corresponding to the address attribute value in the subscription information of the first user equipment to the first user equipment for use.

Step 107: The core network judges whether the address assignment information corresponding to the first user equipment has been cached, if yes, execute step 108, otherwise execute step 109.

Step 108: The core network allocates the IP address in the address allocation information to the first user equipment.

Step 109: The core network selects a new available IP address according to specific rules and assigns it to the first user equipment.

In the dynamic address allocation rule in the technical method of the present application, for each user equipment that successfully performs the attach process, the core network internally caches its address allocation information. The total number of buffered address allocation information is equal to the maximum capacity of the communication system.

Preferably, the cache record of the address allocation information uses the International Mobile Subscriber Identification Number (IMSI, International Mobile Subscriber Identification Number) of the user equipment as a hash table storage method of the key value, so that as the total number of records increases, the user equipment corresponding to The lookup efficiency of cached records will not be reduced. In order to ensure that the same user equipment can be assigned to the last assigned dynamic address for the next attachment, that is, the address in the cache address allocation record, it must be ensured that the last used address of the user equipment is not It will be allocated to other user equipments that initiate the attach process. With the support of the internal cache records of the core network, when the user equipment initiates an attach request, the core network will check whether there is an address allocation information record for the user equipment in the internal cache, and if it exists, it will allocate the address recorded in the cache to meet the requirements of the same user equipment. Multiple attachments can be assigned the same address on demand.

The core network marks each available address as three allocation situations, which are unused (never, address never allocated), used (using, allocated address) and recycling (ever, address recycled by user equipment offline), and used Addresses in the used state are non-allocatable addresses, and addresses in the unused state and reclaimed state are allocatable addresses. The changes among the three states of available addresses are shown in Figure 2. The initial state of all addresses in the address pool configured by the operation and maintenance personnel for the core network is unused. When the address is assigned to a successfully attached user equipment, its state It will become used. When the user equipment is deattached to perform address recycling, the status of the address will change from used to recycled. When the user equipment attaches for the first time, there is no corresponding cached address record information in the core network. The core network will select the unused address for allocation, and will not allocate the address of other user equipment in the offline recovery state, ensuring that the recovery address can continue to be allocated. to the same user device. Usually, the number of available addresses in a well-planned communication system is always greater than the total number of user equipment, so there will be no situation where unused addresses cannot be found. In rare cases, if the number of configured available addresses is less than the total number of user equipment, it may happen that when the user equipment attaches for the first time, the core network can no longer find unused addresses, but there are still reclaimed addresses that can be allocated. In this case, the earliest reclaimed address in the internal cache record is selected for allocation to ensure that there will be no phenomenon that there is an address that can be allocated but the new user equipment is rejected. In this scenario, selecting the earliest reclaimed address also guarantees to a certain extent Recently active user devices that are not currently online can still be assigned the last address the next time they attach.

The technical solution of the present application decides to assign an IP address to the attached user equipment in a static allocation manner according to the address attribute contained in the subscription information of the user equipment. If for some reason multiple user equipments plan the same fixed address, the communication service requirements of the first successfully attached user equipment are guaranteed, and the attachment requests of other user equipments that request the same fixed address after that are rejected. However, since the core network supports both dynamic and static address allocation modes, there is a situation where the fixed address in the subscription information assigned by the core network to the user equipment has been used by another online user equipment. In this case, it is necessary to determine the address used by the online user equipment If it is a static allocation, the new attachment request will be rejected according to the static allocation rules. If it is a dynamic allocation, the current online user equipment will be released, and the address will be reclaimed and allocated to the newly attached user equipment. This ensures that users who request a fixed address The normal communication service of the device, and the released user equipment attaches next time, and the core network will use the dynamic allocation rule to select another available address for allocation.

In order to make the technical principles, features and technical effects of the technical solution of the present application clearer, the technical solution of the present application will be described in detail below in conjunction with specific embodiments.

In the attachment process of the LTE communication protocol, the core network obtains the subscription information of the user equipment during the update location (update location) process. Here, the technical solution of this application first determines the address allocation method as shown in Figure 3, and then performs two different allocation methods. deal with.

In the dynamic address allocation mode, the core network searches for the address allocation information of the current user equipment in the cached address allocation information. The rules are as follows:

1. If it exists and the address is assignable, keep the cache record unchanged;

2. If it exists but the address cannot be assigned, delete the address value in the cache record;

3. If no corresponding cache record is found, add a new cache record without address.

In the first case, the subsequent process will be allocated according to the cache address. In the second and third cases, the subsequent process will select an available address for allocation according to the dynamic type allocation rules.

In the static allocation mode, the present invention further judges the address attribute value of the subscription information, and the rules are as follows:

1. If the address is not within the range of available addresses configured by the operation and maintenance personnel, it will refuse to attach;

2. If the address has been used by another online user equipment in a static way, then refuse to attach;

3. If the address has been dynamically used by another online user device, release the online user device for address recycling, and then add or update the corresponding cache record containing the fixed address as needed;

4. If the address can be allocated, directly add or update the corresponding cache record containing the fixed address as needed.

In cases 1 and 2, the attachment process exits due to rejection. If there is a cache record, it needs to be deleted. In cases 3 and 4, it will be allocated according to the cache address in the subsequent process.

In the process of updating the location, the present invention performs the preparatory processing of the complete address allocation according to the adopted address allocation mode. After the location update process is completed, the attachment process will have two possible results. One result is that the attachment process is rejected for various reasons and the attachment process is exited. The other result is to increase or update the user device cache corresponding to the address or not. The records are processed by subsequent processes. The subsequent process of the process of updating the location is the process of creating a session (create session), that is, the process of allocating an address for the user equipment. In the process of creating a session, the core network judges whether the corresponding user device cache record contains an address. If it does not contain an address, it will select an available address for allocation according to the dynamic allocation rules, and update the selected address to the cache record. If it contains an address, then Assign the specified address, and the status of the address assigned to the user device will become used in both cases.

When the user equipment changes from online to offline, the core network will recycle the address during the process of deleting the session. The core network reclaims the address used by the user equipment that has become offline, changes the address status from used to recycled, and records the time of address recycling in the cache record, so that the offline user equipment in the cache record uses the address recovery time An offline cache record list is formed in an orderly manner, and the offline cache record list provides a basis for overwriting processing when the cache record reaches the maximum capacity and dynamic allocation rules for assigning recycling addresses.

After the core network assigns an address to the user equipment, if the user equipment fails to attach for some reason, the address also needs to be reclaimed in this case. In order to ensure that the address state in this case is consistent with the address state before the attach failure process after recycling, the core network records the original state of the address before changing the state of the allocated address to used during session creation. If the entire attachment process is successfully completed, the original state record will be cleared. Once the attachment fails after the session is created, the address will be restored to the original state, that is, the original state is unused and still unused, and the original state is recycled. , and also delete the corresponding cache record, which effectively prevents the damage to the dynamic allocation rule caused by the consumption of unused addresses in the continuous attachment failure scenario.

Embodiment 1 of the present invention is shown in Figure 3, the core network manages user equipment address allocation according to user equipment subscription information during the location update process, including the following steps:

Step 301 , the core network judges the subscription information of the user equipment. If the subscription information contains valid address attributes, go to step 302 ; otherwise, go to step 303 .

Step 302, the core network judges the address attribute in the subscription information, if the address is included in the available address range configured by the operation and maintenance personnel, go to step 304, otherwise go to step 307.

Step 303 , the core network checks whether there is a cache record of the user equipment, if yes, go to step 309 , otherwise go to step 311 .

Step 304 , the core network further judges the current allocation state of the address in the subscription information, if the address can be allocated, go to step 308 , otherwise go to step 305 .

Step 305 , the address in the subscription information has been allocated to another online user equipment, the core network checks the address allocation method of the online user equipment, if it is dynamic, go to step 306 , otherwise go to step 307 .

Step 306, the core network releases the online user equipment, reclaims its address, and goes to step 308.

In step 307, the core network rejects the attachment of the user equipment, and deletes possible cache records, and the process ends.

Step 308, the core network adds or updates the cache record containing the address in the subscription information as needed.

Step 309 , the core network judges the current allocation status of the address in the cache record, and if the address can be allocated, no processing is performed; otherwise, go to step 310 .

Step 310, the core network deletes the address value in the cache record.

In step 311, the core network adds a cache record that does not include an address.

Example 2

Embodiment 2 of the present invention is shown in Figure 4. When assigning an address to a user equipment in a dynamic manner, if there is no cache record of the user equipment or the cache record does not contain an address, the rules for the core network to select an address for the user equipment are as follows:

Step 401 , the core network checks the allocation of currently configured available addresses, if there is an unused address, go to step 402 , otherwise go to step 403 .

In step 402, the core network allocates an unused address for the user equipment, and the address allocation is successful.

Step 403, the core network checks whether there is an address that can be allocated, and if so, go to step 404, otherwise, the address allocation fails.

In step 404, the core network allocates the earliest reclaimed address to the user equipment according to the time-ordered offline cache record list, and the address allocation is successful.

Example 3

Embodiment 3 of the present invention is shown in Figure 5, the core network manages the user equipment address allocation during the session creation process, including the following steps:

Step 501 , the core network checks the cache record of the user equipment, if the cache record contains an address, go to step 502 , otherwise go to step 503 .

Step 502, the core network allocates the address in the cache record to the user equipment.

In step 503, the core network assigns an address to the user equipment according to the dynamic allocation rules. If the allocation is successful, go to step 504; otherwise, go to step 505; the specific allocation rules are the same as those in Embodiment 2, and will not be repeated here.

Step 504, the core network updates the cache record and adds the address allocated to the user equipment.

Step 505, the core network rejects the attachment of the user equipment, deletes the corresponding cache record, and the process ends.

The above descriptions are only preferred embodiments of the application, and are not intended to limit the scope of protection of the application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the technical solutions of the application are It should be included within the protection scope of this application.

Claims (10)

1. A user equipment address management method, characterized in that, for each user equipment that successfully attaches to the process, its address allocation information is cached inside the core network; the method includes: A. The first user equipment initiates an attach request, and the core network determines the address allocation method of the first user equipment according to whether the subscription information of the first user equipment contains address attributes. If the address attribute is included, step B is performed; if the address attribute is not included Then execute step C; B. The core network assigns a static address to the first user equipment according to the address attribute in the subscription information of the first user equipment, and ends this process; C. The core network performs dynamic address allocation to the first user equipment, and ends this process; during the dynamic address allocation process, if the core network finds that the address allocation information corresponding to the first user equipment has been cached, then the cached first user equipment The IP address in the corresponding address allocation information is allocated to the first user equipment. 2. The method according to claim 1, wherein step B comprises: B1. The core network judges whether there is an online second user equipment whose address is the same as the address attribute value in the subscription information of the first user equipment. If it is, step B2 is executed; otherwise, step B5 is executed; B2. The core network judges whether the address of the second user equipment is acquired statically or dynamically. If it is acquired statically, execute step B3, otherwise execute step B4; B3. The core network rejects the attachment request of the first user equipment, and ends this process; B4. The core network allocates the address corresponding to the address attribute value in the subscription information of the first user equipment to the first user equipment for use, notifies the second user equipment to reacquire a new IP address in a dynamic manner, and ends this process; B5. The core network allocates the address corresponding to the address attribute value in the subscription information of the first user equipment to the first user equipment for use, and ends this process. 3. The method according to claim 2, wherein step C comprises: C1. The core network judges whether the address allocation information corresponding to the first user equipment has been cached and the IP address in the address allocation information is not used by other online user equipment, if so, execute step C2, otherwise execute step C3; C2. The core network allocates the IP address to the first user equipment, and ends this process; C3. The core network selects a new available IP address according to a specific rule and assigns it to the first user equipment, and ends this process. 4. The method according to claim 1, wherein the cache record of the address assignment information adopts a hash table storage method in which the International Mobile Subscriber Identity (IMSI) of the user equipment is used as a key value. 5. The method according to claim 1, wherein the total number of buffered address allocation information is equal to the maximum capacity of the communication system. 6. The method according to claim 3, wherein the core network marks each available address as three allocation situations, namely unused, used and reclaimed, the used address is an unallocated address, and the unused address is an unallocated address. Addresses in the use state and recycling state are allocatable addresses; Step B1 includes: the core network judges whether there is an online second user equipment whose address is the same as the address attribute value in the subscription information of the first user equipment, if so, execute step B2, otherwise add or update the corresponding cache record of the first user equipment and execute Step B5; Step B2 includes: the core network judges whether the address of the second user equipment is acquired statically or dynamically, and if it is statically acquired, then delete the cache record that may exist in the first user equipment and perform step B3, otherwise add or update the first user equipment Corresponding cache record and execute step B4; Step C1 includes: the core network judges whether the address allocation information corresponding to the first user equipment has been cached, if it exists and the address corresponding to the address allocation information is allocatable, then keep the cache record unchanged and execute C2; if it exists but the address If it cannot be allocated, delete the address value in the cache record and execute C3; if no corresponding cache record is found, add a cache record without address and execute C3. 7. The method according to claim 6, further comprising: the first user equipment changes from an online state to an offline state, and the core network changes the address state of the first user equipment from used to Change to recycling, and record the time of address recycling into the cache record, so that the offline user equipment in the cache record forms an offline cache record list in order according to the address recycling time. 8. The method according to claim 7, wherein the core network performing dynamic address allocation or static address allocation to the first user equipment comprises: The core network records the original state of the address to be allocated; The core network allocates a dynamic address or a static address to the first user equipment, and changes the status of the allocated address to used; If the entire attaching process is successfully completed, the original state record is cleared, and once an attaching failure occurs after the session is created, the address is restored to the original state. 9. The method according to claim 7, wherein step C3 comprises: C3-1. The core network checks the allocation of currently configured available addresses. If there is an unused address, go to step C3-2, otherwise go to step C3-3; C3-2. The core network assigns an unused address to the first user equipment, and ends this process; C3-3. The core network checks whether there is an address that can be allocated. If there is, go to step C3-4. Otherwise, the address allocation fails to end this process; C3-4. The core network assigns the earliest reclaimed address to the first user equipment according to the time-ordered offline cache record list, and ends this process. 10. The method according to claim 9, wherein step C3-2 and step C3-4 further comprise: the core network updates the cache record to increase the address assigned to the first user equipment; and, After the address allocation fails in step C3-3, it further includes: deleting the corresponding cache record of the first user equipment.