WO2013026299A1

WO2013026299A1 - Address resolution method and device, and information transmission method

Info

Publication number: WO2013026299A1
Application number: PCT/CN2012/076254
Authority: WO
Inventors: 曹笑
Original assignee: 中兴通讯股份有限公司
Priority date: 2011-08-22
Filing date: 2012-05-30
Publication date: 2013-02-28
Also published as: CN102957755A; CN102957755B

Abstract

An address resolution method and device, and an information transmission method. The address resolution method includes: after a source access server (ASR) to which source user equipment (UE) belongs has received an address resolution protocol (ARP) broadcasting request message from the source UE, applying the location identifier of target UE to secondarily encapsulate the ARP broadcasting request message, and sending the secondarily encapsulated APR broadcasting request message to a target ASR to which the target UE belongs; and the target ASR decapsulating the received secondarily encapsulated ARP broadcasting request message, sending the obtained ARP broadcasting request message to the target UE to acquire the media access control (MAC) address of the target UE, and sending to the source UE the MAC address of the target UE via the source ASR. The present application can highly efficiently and rapidly acquire the MAC address of the UE which is not in a unified broadcasting domain.

Description

Address analysis method, device and information transmission method

Technical field

The present invention relates to the field of mobile communications and the Internet, and in particular, to an address resolution method, apparatus, and information transmission method.

Background technique

Mobile Internet is the future development direction of the Internet, but mobility management is a big problem facing the mobile Internet. As we all know, if a terminal wants to access the IP Internet, it must apply for a valid IP address from the network. The IP address has a dual attribute that represents both the identity of the user and the location of the network topology in which the user is located. When the user gets a location in a topology (such as under an access gateway)

After an IP address, the IP address can only be used in the topology (for example, it can only be used within the jurisdiction of an access router). This is of course no problem for a fixed terminal, but for a mobile terminal, the above IP address becomes an invalid address after the terminal moves from the range governed by one access router to the range governed by another access router. At this point, the terminal must re-acquire a new IP address from the new topology. In this way, the continuity of the IP-based upper layer service cannot be guaranteed. For example, if the end user is making an IP call, the call will be broken.

In order to solve this problem, the industry began to study the technology based on identity location separation. This technology attempts to solve the problem that the terminal must reassign the IP address after crossing the access router. The basic principle is to assign an identity to the terminal and assign a location identifier. .

As shown in Figure 1, it is an architecture of identity information and location information separation network. The system consists of Access Service Router (ASR), User Equipment (UE), and Identity Location Register (Identification). And the location register (ILR) and the authentication center (AC), wherein the access server ASR is used to access the user equipment, and the location identifier is assigned to the user equipment; the ILR is used to save the current location information of the user, and The function of querying the current location information according to the user's identity information is provided to the outside world; the AC assumes the user access authentication function; the DHCP assumes the assignment function of the unique identifier (Access Identification, AID), and the assigned AID must belong to the same subnet. The user equipment (or host) has a unique identity (AID). The AID of the user equipment remains unchanged regardless of the ASR in the network. When the user equipment accesses the network, it will be A location identifier (RID) is assigned to indicate the topology location (characterized routing information) that the terminal is currently located, and is generally assigned by the ASR currently connected by the user equipment.

In the network where the identity locations are separated, when the two user terminals need to communicate, the two parties use their respective AIDs as the source/destination addresses of the communication. Take Figure 1 as an example. 4 Set UE1 as the source (transmitting end) and UE2 as the destination. The terminal (receiving end), the step of UE1 communicating with UE2 includes:

(1) The source sends the IP packet to the ASR1 connected to the source;

(2) ASR1 obtains the current RID of the destination end according to the AID of the destination end, and tunnels the data packet sent by the source end (for example, IP in IP tunnel), and sends the encapsulated packet to the destination end. ASR2, where the source/destination address of the tunnel is the RID of the source end and the RID of the destination end, respectively;

(3) ASR2 disassembles the tunnel and takes out the packet sent by the source end and sends it to the destination.

ARP (Address Resolution Protocol) is a technology for address mapping and conversion from the network layer to the data link layer. That is, IP address to MAC address mapping and conversion. ARP packets can only be transmitted in one broadcast domain. Routers do not forward ARP packets. Text.

As shown in Figure 1, AID1 of UE1 and AID2 of UE2 belong to the same subnet, but UE1 and UE2 are not in the same broadcast domain. Therefore, when UE1 performs data communication with UE2, UE1 cannot find UE2.

The process of data communication between UE1 and UE2 is as follows:

UE1 checks whether UE2 and itself are in the same subnet. If yes, UE1 directly sends an ARP broadcast request packet to query the MAC address of UE2. Since the router does not forward the ARP broadcast request packet, and UE2 and UE1 are not in the same broadcast domain, Therefore UE1 cannot find UE2 and communication fails.

Summary of the invention

The technical problem to be solved by the present invention is to provide an address resolution method, device and information transmission side The method can obtain the MAC addresses of UEs that are not in the same broadcast domain in the identity and location separation network.

To solve the above technical problem, an address resolution method of the present invention includes:

After receiving the address resolution protocol (ARP) broadcast request message of the source UE, the source access server (ASR) to which the source user equipment (UE) belongs performs the second ARP broadcast request message by using the location identifier of the target UE. Sub-encapsulation, and the secondary encapsulated ARP broadcast request message is sent to the target ASR to which the target UE belongs;

The target ASR decapsulates the received secondary encapsulated ARP broadcast request message, and sends the obtained ARP broadcast request message to the target UE to obtain the media access control (MAC) of the target UE. Addressing, and transmitting, by the source ASR, the MAC address of the target UE to the source UE.

Preferably, the method further comprises:

Carrying the identity identifier of the target UE in the ARP broadcast request message;

After receiving the ARP broadcast request message, the source ASR parses the ARP broadcast request message to obtain the identity identifier of the target UE, and queries the home location register for the target UE according to the identity identifier of the target UE. The location identifier, and performing the location identifier of the target UE to perform secondary encapsulation on the ARP broadcast request>3⁄4.

Preferably, the method further includes: after the target ASR sends the decapsulated ARP broadcast request message to the target UE, and receives an ARP response packet returned by the target UE, where the ARP response packet carries The MAC address of the target UE.

Preferably, the method further includes: after receiving the ARP response packet returned by the target UE, the target ASR queries the home location register for the location identifier of the source UE according to the identity identifier of the source UE, according to the source a location identifier of the UE, where the MAC address of the target UE is sent to the source UE by using the source ASR.

Preferably, the method further comprises:

After receiving the ARP response packet returned by the target UE, the target ASR passes the source identifier of the source UE obtained by decapsulating the secondary encapsulated ARP broadcast request packet, and passes the source The ASR sends the MAC address of the target UE to the source UE. Preferably, the target ASR sends the MAC address of the target UE to the source UE by using the source ASR according to the location identifier of the source UE, including:

The target ASR performs a second encapsulation on the ARP response according to the location identifier of the source UE, and sends the second encapsulated ARP response packet to the source ASR.

The source ASR decapsulates the received ARP response packet, and obtains an ARP response packet, and sends the ARP response packet to the source UE.

Preferably, the method further includes: after querying the location identifier of the target UE, the source ASR checks whether the location identifier of the target UE is the same as its own address, and if the same, the source UE and the target UE belong to the same broadcast. Domain, discarding the location identifier of the target UE.

An information transmission method includes: after receiving, by the first server to which the first user equipment (UE) belongs, the first UE to query a request message of a media access control (MAC) address of the second UE, The second identifier of the second UE is used to perform the second encapsulation of the request packet, and the second encapsulated request packet is sent to the second server to which the second UE belongs, and the received second packet is decapsulated. The packet returned by the server obtains a response packet, and sends the response packet to the first UE.

Preferably, the identifier of the second UE is carried in the request packet;

After receiving the request message, the first server parses the request message to obtain the identity of the second UE, and queries the third server according to the identity of the second UE to query the second UE. The location identifier is configured to perform secondary encapsulation on the request packet by using the location identifier of the second UE, and send the second encapsulated request packet to the second server.

Preferably, after the first server queries the location identifier of the second UE, it is checked whether the location identifier of the second UE is the same as the address of the second UE. If they are the same, the first UE and the second UE are the same. Broadcast domain, discarding the location identifier of the second UE.

An information transmission method includes: receiving, by a second server to which the second UE belongs, a request packet that is sent by the first server to which the first UE belongs, and is secondarily encapsulated by the location identifier of the second UE, where The sub-encapsulated request packet is decapsulated to obtain a request message for querying a media access control (MAC) address of the second UE, and the request packet is sent to the second UE to obtain the a MAC address of the second UE, and sending, by the first server, a MAC address of the second UE to the first UE. Preferably, after the second server sends the request message to the second UE, it receives a response message returned by the second UE, where the response message carries the MAC address of the target UE. .

Preferably, after receiving the response message returned by the second UE, the second server queries the third server for the location identifier of the first UE according to the identity identifier of the first UE, according to the And a location identifier of the UE, where the MAC address of the second UE is sent by the first server to the first UE.

Preferably, after receiving the response message returned by the second UE, the second server passes the location identifier of the first UE obtained by decapsulating the request packet after the secondary encapsulation. The first server sends a MAC address of the second UE to the first UE.

Preferably, the sending, by the second server, the MAC address of the second UE to the first UE by using the first server includes:

The second server performs secondary encapsulation on the response packet according to the location identifier of the first UE, and sends the second encapsulated response packet to the first server.

Preferably, an address resolution apparatus includes: a message receiving unit, a message encapsulating unit, a message sending unit, and a decapsulation unit, where:

The packet receiving unit is configured to: receive a request message sent by the first user equipment (UE) for querying a media access control (MAC) address of the second UE;

The packet encapsulating unit is configured to: after the packet receiving unit receives the request message, use the location identifier of the second UE to perform secondary encapsulation on the request packet, and pass the report The message sending unit sends the second encapsulated request message to the second server to which the second UE belongs; the decapsulation unit is configured to: decapsulate the second server return received by the message receiving unit And sending a response message to the first UE by using the message sending unit.

Preferably, the query unit is further configured to: after the receiving unit receives the request message, parsing the request message to obtain the identity of the second UE, according to the The identifier of the second UE is queried to the third server for the location identifier of the second UE, and the location identifier of the second UE is sent to the packet encapsulation unit. Preferably, the identifier checking unit is further configured to: after the query unit queries the location identifier of the second UE, check whether the location identifier of the second UE is the same as its own address, If the same, the first UE and the second UE belong to the same broadcast domain, and the query unit is notified to discard the location identifier of the second UE.

Preferably, the message receiving unit is further configured to: receive a request message that is sent by the third server to which the third UE belongs, and is encapsulated by the location identifier of the first UE;

The decapsulating unit is further configured to: decapsulate the request packet after the secondary encapsulation by using the location identifier of the first UE, to obtain a request for querying a media access control (MAC) address of the first UE Transmitting, by the message sending unit, the request message to the first UE, to obtain a MAC address of the first UE;

The packet encapsulating unit is further configured to: send, by the third server, a MAC address of the first UE to the third UE.

Preferably, the message receiving unit is further configured to: receive a response message returned by the first UE, where the response message carries a MAC address of the target UE.

Preferably, the query unit is further configured to: receive the first in the message receiving unit

After the response message returned by the UE, the location identifier of the third UE is queried to the third server according to the identity identifier of the third UE;

The packet encapsulating unit is configured to: send, according to the location identifier of the third UE, the MAC address of the first UE to the third UE by using the third server.

Preferably, the packet encapsulating unit is configured to: obtain the third according to the decapsulation unit when decapsulating the request packet after the secondary encapsulation by using the location of the first UE a location identifier of the UE, where the MAC address of the first UE is sent to the third UE by using the third server.

Preferably, the message encapsulating unit is configured to: perform secondary encapsulation on the response according to the location identifier of the third UE, and respond to the secondary encapsulation by using the message sending unit; The text is sent to the third server.

In summary, in the embodiment of the present invention, the ARP broadcast request packet is forwarded to the broadcast domain where the destination terminal is located, so that the MAC address of the destination terminal is obtained, so that the acquisition is not performed efficiently and quickly. The MAC address of the UE in the unified broadcast domain. BRIEF abstract

Figure 1 is an architectural diagram of an identity and location separation network;

2 is a flowchart of an address resolution method according to an embodiment of the present invention;

3 is a block diagram of an address analysis apparatus according to the embodiment. Preferred embodiment of the invention

Considering that in the identity and location separation network, the user equipment (source user equipment) cannot obtain the media access control (MAC) of another user equipment (target user equipment) that is not in the same broadcast domain through ARP address resolution. Address, and thus data communication is not possible. In this embodiment, the ASR of the source user equipment performs the secondary encapsulation of the ARP broadcast request packet, and forwards the ARP broadcast request packet to the broadcast domain where the target user equipment is located, so as to obtain the MAC address of the target user equipment.

In this embodiment, the MAC address of the target user equipment that is not in the same broadcast domain in the identity and location separation network needs to be unique based on the identity of the user equipment (AID). This is a prerequisite for ARP address resolution.

Referring to FIG. 1, the source user equipment UE1 and the target user equipment UE2 access the network through ASR1 and ASR2, respectively, and need to pass the authentication center (AC) for access authentication. After the authentication succeeds, the ASR reports the location information of the user equipment to the user equipment. The identity location register (ILR), so the location identifier of the user equipment queried on the ILR is the location identifier of the broadcast domain to which the user equipment belongs. This embodiment queries the location identifier of the target user equipment from the ILR, and uses the queried target user equipment. The location identifier is used to perform secondary encapsulation on the ARP broadcast request packet of the source user equipment, and is sent to the broadcast domain of the target user equipment. After the target user equipment responds, the result is returned to the broadcast domain of the source user equipment, and then sent. Give the source user device the source user device to obtain the MAC address of the target user device.

The embodiments are described below based on the drawings. It should be noted that the content of the embodiment may be explained by the following embodiments, but is not limited to the following embodiments. The following takes the source user equipment UE1 to initiate data communication with the target user equipment UE2 as an example. The UE1 does not know the MAC address of the UE2. Referring to FIG. 1 and FIG. 2, the address resolution method in the identity identification and location separation network in this embodiment includes:

Step 201: The UE1 sends an ARP broadcast request message to the ASR1, requesting the MAC address of the UE2, and carrying the identity identifier of the UE2 in the ARP broadcast request message;

Step 202: After detecting the ARP broadcast request message of the UE1, the ASR1 parses the ARP broadcast request message, and obtains the identity of the UE2.

Step 203: The ASR1 sends a query request to the ILR, and carries the identity identifier of the UE2 in the query request, and requests to query the location identifier of the UE2.

Step 204: After receiving the query request of the ASR1, the ILR queries the location identifier of the UE2 according to the identity of the UE2, and returns the location identifier of the UE2 to the ASR1.

After obtaining the location identifier of the UE2, the ASR1 checks whether the location identifier of the UE2 is the same as the address of the ASR1. If they are the same, the UE1 and the UE2 belong to the same broadcast domain, and the ASR1 discards the location identifier.

When ASR1 queries the location identifier of UE2 from the ILR, if the location identifier of UE2 is empty, it indicates

UE2 does not access the network, and ASR1 discards the invalid location identifier.

Step 205: ASR1 uses the location identifier of the UE2 to perform a second encapsulation on the ARP broadcast request, and sends the second encapsulated ARP broadcast request message to the ASR2.

For example, ASR1 can perform secondary encapsulation on ARP broadcast requests in a tunnel or the like. Step 206: The ASR2 decapsulates the ARP broadcast request sent by the ASR1, and obtains an ARP broadcast request message, and sends an ARP broadcast request message in a broadcast manner.

ASR2 sends an ARP broadcast request message to UE2 in broadcast mode to obtain the MAC address of UE2.

Step 207: After receiving the ARP broadcast request message, the UE2 returns an ARP response message to the ASR2, and carries the MAC address of the UE2.

Step 208: ASR2 obtains the AID of the UE1 from the ARP broadcast request message, queries the ILR for the location identifier of the UE1, and uses the location identifier of the UE1 to perform the secondary encapsulation of the ARP response packet, and the ARP response packet after the secondary encapsulation. Sent to ASR1; The ASR2 can also obtain the location identifier of the UE1 when the ARP broadcast request packet sent by the ASR1 is decapsulated, so that the location identifier of the UE1 does not need to be queried to the ILR.

Step 209: The ASR1 decapsulates the ARP response packet sent by the ASR2 to obtain the ARP response packet, and sends the ARP response packet to the UE1.

At this point, UE1 obtains the MAC address of UE2, and can perform data communication with UE2.

As shown in FIG. 3, the embodiment further provides an address resolution apparatus, including: a message receiving unit, a message encapsulating unit, a message sending unit, and a decapsulating unit, where:

a message receiving unit, configured to receive a request message sent by the first UE for querying a MAC address of the second UE;

The message encapsulating unit is configured to: after the message receiving unit receives the request message, use the location identifier of the second UE to perform secondary encapsulation on the request packet, and the second packet is encapsulated by the packet sending unit. Sending to the second server to which the second UE belongs;

The decapsulating unit is configured to decapsulate the packet returned by the second server received by the packet receiving unit, and obtain a response packet, and send the response packet to the first UE by using the packet sending unit.

The device further includes a query unit, configured to: after the message receiving unit receives the request message, parse the request message to obtain the identity of the second UE, and query the third server for the second UE according to the identity of the second UE. The location identifier is sent to the packet encapsulating unit of the second UE.

The device further includes an identifier checking unit, configured to check whether the location identifier of the second UE is the same as the address of the second UE after the query unit queries the location identifier of the second UE, and if the same, the first UE and the second UE The UE belongs to the same broadcast domain, and the notification query unit discards the location identifier of the second UE.

The message receiving unit is further configured to receive, after receiving, the second encapsulated request message by using the location identifier of the first UE that is sent by the third server to which the third UE belongs;

The decapsulating unit is further configured to decapsulate the request packet after the secondary encapsulation by using the location identifier of the first UE, to obtain a request packet for querying a media access control (MAC) address of the first UE, by using a packet sending unit Sending the request message to the first UE, to obtain the MAC address of the first UE;

The packet encapsulating unit is further configured to send the MAC address of the first UE to the third UE by using the third server. The message receiving unit is further configured to receive a response message returned by the first UE, where the response message carries the MAC address of the target UE.

The Querying Unit is further configured to: after the message receiving unit receives the response message returned by the first UE, query the third server for the location identifier of the third UE according to the identity identifier of the third UE;

The packet encapsulating unit is configured to perform secondary encapsulation on the response packet according to the location identifier of the third UE, and send the response packet after the secondary encapsulation to the third server by using the packet sending unit. Or the packet encapsulating unit performs secondary encapsulation on the response packet according to the location identifier of the third UE obtained by decapsulating the request packet after the decapsulation of the first UE by using the location of the first UE. The text sending unit sends the secondary encapsulated response message to the third server.

Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general-purpose computing device, which can be concentrated on a single computing device or distributed over a network composed of multiple computing devices. Alternatively, they may be implemented by program code executable by the computing device, such that they may be stored in the storage device by the computing device and, in some cases, may be different from the order herein. The steps shown or described are performed, or they are separately fabricated into individual integrated circuit modules, or a plurality of modules or steps are fabricated as a single integrated circuit module. Thus, the invention is not limited to any particular combination of hardware and software.

The above description is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Industrial Applicability In the embodiment of the present invention, the ARP broadcast request packet is forwarded to the broadcast domain where the destination terminal is located, so that the MAC address of the destination terminal is obtained, so that the MAC address of the UE that is not in the unified broadcast domain is efficiently and quickly obtained.

Claims

Claim

1. An address resolution method, including:

2. The method according to claim 1, further comprising:

3. The method according to claim 1, further comprising:

After the target ASR sends the decapsulated ARP broadcast request message to the target UE, it receives an ARP response packet returned by the target UE, where the ARP response packet carries the MAC address of the target UE. .

4. The method of claim 3, further comprising:

After receiving the ARP response packet returned by the target UE, the target ASR queries the home location register for the location identifier of the source UE according to the identity identifier of the source UE, and passes the location identifier of the source UE. The source ASR sends the MAC address of the target UE to the source UE.

5. The method of claim 3, further comprising: After receiving the ARP response packet returned by the target UE, the target ASR passes the source identifier of the source UE obtained by decapsulating the secondary encapsulated ARP broadcast request packet, and passes the source The ASR sends the MAC address of the target UE to the source UE.

The method according to claim 4 or 5, wherein the target ASR sends the MAC address of the target UE to the source UE by using the source ASR according to the location identifier of the source UE, including:

7. The method of claim 2, further comprising:

After the source ASR queries the location identifier of the target UE, it checks whether the location identifier of the target UE is the same as the address of the target UE. If they are the same, the source UE and the target UE belong to the same broadcast domain, and discard the The location identifier of the target UE.

8. An information transmission method, comprising:

After receiving the request message that the first UE queries the media access control (MAC) address of the second UE, the first server to which the first user equipment (UE) belongs, uses the location identifier of the second UE Transmitting the request packet to the second server to which the second UE belongs, and decapsulating the received packet returned by the second server, and obtaining a response. Sending, by the message, the response message to the first UE.

9. The method of claim 8 wherein

Carrying the identity identifier of the second UE in the request packet;

10. The method of claim 9, wherein

After the first server queries the location identifier of the second UE, it is checked whether the location identifier of the second UE is the same as the address of the second UE. If they are the same, the first UE and the second UE belong to the same broadcast domain. And discarding the location identifier of the second UE.

11. A method of information transmission, comprising:

The second server to which the second user equipment (UE) belongs receives the request packet sent by the first server to which the first UE belongs, and is encapsulated by the location identifier of the second UE, after the secondary encapsulation And requesting the packet to be decapsulated, and obtaining a request message for querying a media access control (MAC) address of the second UE, and sending the request packet to the second UE, to obtain the second UE. a MAC address, and sending, by the first server, a MAC address of the second UE to the first UE.

12. The method of claim 11 wherein

After the second server sends the request packet to the second UE, it receives a response packet returned by the second UE, where the response packet carries a MAC address of the target UE.

13. The method of claim 12, wherein

After receiving the response message returned by the second UE, the second server queries the third server for the location identifier of the first UE according to the identity identifier of the first UE, according to the first UE a location identifier, where the MAC address of the second UE is sent by the first server to the first UE.

14. The method of claim 12, wherein

After receiving the response message returned by the second UE, the second server, according to the location identifier of the first UE obtained when decapsulating the request packet after the secondary encapsulation, passes the A server sends the MAC address of the second UE to the first UE.

The method according to claim 13 or 14, wherein the sending, by the second server, the MAC address of the second UE to the first UE by using the first server includes:

The second server performs the response packet twice according to the location identifier of the first UE. Encapsulating, the secondary encapsulated response message is sent to the first server.

An address resolution apparatus, comprising: a message receiving unit, a message encapsulating unit, a message sending unit, and a decapsulating unit, wherein:

17. The apparatus of claim 16, further comprising a query unit;

The querying unit is configured to: after the packet receiving unit receives the request message, parse the request message to obtain an identity of the second UE, according to the identity of the second UE The third server queries the location identifier of the second UE, and sends the location identifier of the second UE to the packet encapsulation unit.

The device according to claim 17, further comprising an identifier checking unit, wherein the identifier checking unit is configured to: after the query unit queries the location identifier of the second UE, check the second UE The location identifier is the same as the address of the second UE. If the same, the first UE and the second UE belong to the same broadcast domain, and the query unit is notified to discard the location identifier of the second UE.

19. The apparatus according to claim 16, wherein

The packet receiving unit is further configured to: receive a request packet that is sent by the third server to which the third UE belongs, and is secondarily encapsulated by using the location identifier of the first UE;

The decapsulating unit is further configured to: decapsulate the request packet after the secondary encapsulation by using the location identifier of the first UE, to obtain a medium access control (MAC) address of the first UE. And requesting the message, the message sending unit sends the request message to the first UE, to obtain the MAC address of the first UE;

20. The apparatus according to claim 19, wherein

The packet receiving unit is further configured to: receive a response packet returned by the first UE, where the response packet carries a MAC address of the target UE.

21. The apparatus according to claim 20, wherein

The querying unit is further configured to: after the message receiving unit receives the response message returned by the first UE, query the third server for the location of the third UE according to the identity identifier of the third UE Identification

22. The apparatus according to claim 20, wherein

The packet encapsulating unit is configured to: locate, according to the decapsulating unit, the third UE obtained by decapsulating the request packet after the secondary encapsulation by using the location of the first UE And sending, by the third server, the MAC address of the first UE to the third UE.

23. The apparatus according to claim 21 or 22, wherein

The packet encapsulating unit is configured to: perform secondary encapsulation on the response packet according to the location identifier of the third UE, and send, by using the packet sending unit, the secondary encapsulated response packet to the Third server.