WO2009143729A1

WO2009143729A1 - Method, system and apparatus for realizing dhcp user service wholesale

Info

Publication number: WO2009143729A1
Application number: PCT/CN2009/071333
Authority: WO
Inventors: 郝卫国; 王建兵; 潘灏涛
Original assignee: 华为技术有限公司
Priority date: 2008-05-27
Filing date: 2009-04-17
Publication date: 2009-12-03
Also published as: CN101272403A; CN101272403B

Abstract

A method, a system and an apparatus for realizing DHCP user service wholesale are provided in the embodiment of the present invention. The method comprises the following steps: receiving the data message transmitted from the terminal, and packing the said data message in terms of L2TPv3; obtaining the L2TPv3 tunnel which is corresponding to the said terminal, and transmitting the packed data message to the L2TP network service device LNS through the corresponding L2TPv3 tunnel; receiving the response message transmitted by the said LNS through the L2TPv3 tunnel; unpacking the said response message and transmitting it to the said terminal. With the embodiment of the present invention, the LAC device maps the message of the terminal to the L2TPv3 tunnel, and transmits it to the remote LNS device through the L2TPv3 tunnel, the interaction with the network is achieved by the LNS device, thereby the DHCP user service wholesale is realized. In the embodiment of the present invention, the L2TPv3 tunnel can be built in the common IP network with the advantages of simple technique and low cost of network configuration.

Description

Method, system and device for realizing wholesale of DHCP user service This application claims to be submitted to the Chinese Patent Office on May 27, 2008, with the application number of 200810097465.8, and the invention titled "Method, System and Equipment for Realizing the Wholesale of DHCP User Service" Priority of the application, the entire contents of which are incorporated herein by reference. Technical field

The embodiments of the present invention relate to the field of communications technologies, and in particular, to a method, system, and device for implementing a DHCP (Dynamic Host Configuration Protocol) user service wholesale. Background technique

According to the affiliation, the broadband access network can be divided into an NSP (Network Service Provider) network and an ISP (Internet Service Provider) network. The NSP network is generally built, managed, and maintained by operators to provide users with high-speed access, traffic aggregation, and policy enforcement.

Service wholesale is a technology that promotes the separation of ISP and NSP. ISPs manage and develop users by renting NSP networks. Users use the services provided by ISPs. NSP provides ISPs with data transmission channels, and through subsequent reconciliation, they guarantee their respective income. Service wholesale is generally carried out through the Layer 2 tunneling technology. User packets are transmitted to the remote ISP network through the Layer 2 tunnel. The ISP processes user access, authentication, authorization, and other user management policies. The NSP uses the tunnel to isolate and transmit services. , wholesale.

The IP session (IP session) is defined in the prior art, including a PPP (Point to Point Protocol) Session and a DHCP Session. For the PPP terminal, the user is wholesaled through the L2TPv2 (Layer 2 Tunneling Protocol version 2) tunnel, and the user access authentication, address allocation, and service management are performed on the remote ISP. The LAC is the NSP network resource. (L2TP Access Concentrator, L2TP access concentrator) can be used on the device according to the user domain name information. The user data is mapped to the L2TP tunnel and transparently transmitted to the remote ISP device. For the DHCP terminal, the PW (Pseudo Wire) pipeline of the VPLS (Virtual Private LAN Services) network is generally used for wholesale, and the intermediate device needs to support MPLS (Multi Protocol Label Switch). .

FIG. 1 is a schematic diagram of a network for implementing static service wholesale using a VPLS network in the prior art. The specific steps for the VPLS network to be used for wholesale DHCP access users are as follows: (1) Configure the user access VLAN or DHCP protocol packet Option 60 and VSI (Virtual Switch) on the Layer 2 switch PE (Provider Edge, Carrier Network Edge). The corresponding relationship between the Instance and the virtual switch instance, the user receives the Layer 2 packet from the access network, and sends the packet to the PW of the corresponding VSI. (2) The user encapsulates the Layer 2 packet and sends the packet to the link through the PW pipe. The remote device of the ISP network terminates the two-layer label of the PW pipe at the remote device, restores the original user Layer 2 packet, and sends it to the BNG (Broad Network Gateway, broadband network gateway) for processing; (3) BNG performs the user. Address allocation and access control. At the same time, each VPN (Virtual Private Network) is used to provide a transmission channel for each ISP on the NSP network to isolate user data traffic of different ISPs through the VPN.

In carrying out the process of the present invention, the inventors have found that the prior art has at least the following problems:

The above implementation depends on the PW pipeline established by the MPLS network for wholesale, and the networking cost is high. When the service is wholesaled through the VPLS network, the VPLS cross-domain is usually involved, and the technical implementation is complicated. Summary of the invention

The embodiment of the invention provides a method, a system and a device for realizing the wholesale of a DHCP user service, which are used for implementing the wholesale of the DHCP user.

To achieve the above objective, an embodiment of the present invention provides a method for implementing a DHCP user service wholesale, including:

Receiving a data packet sent by the terminal, and performing the L2TPv3 encapsulation on the data packet; Obtaining an L2TPv3 tunnel corresponding to the terminal, and sending the encapsulated data packet to the L2TP network service device LNS through the corresponding L2TPv3 tunnel;

Receiving a response packet sent by the LNS through the L2TPv3 tunnel;

And decapsulating the response packet and sending the response packet to the terminal.

The embodiment of the present invention further provides an L2TP access centralized device LAC, including: an encapsulating unit, configured to perform L2TPv3 encapsulation on the data packet when receiving the data packet sent by the terminal;

The tunnel obtaining unit is configured to obtain the L2TPv3 tunnel corresponding to the terminal, and send the data packet encapsulated by the encapsulating unit to the L2TP network service device LNS through the corresponding L2TPv3 tunnel;

a response message receiving unit, configured to receive a response sent by the LNS through the L2TPv3 tunnel;

And a decapsulation unit, configured to decapsulate the response message received by the response message receiving unit.

An embodiment of the present invention further provides an L2TP network server LNS device, including: a decapsulation unit, configured to perform L2TPv3 tunnel decapsulation on a received data packet; and a forwarding unit, configured to decapsulate according to the decapsulation unit The destination IP address of the data packet is used to find a routing table, and the data packet is forwarded to the destination device.

The tunnel obtaining unit is configured to: when receiving the response packet sent by the destination device, obtain an outbound interface L2TPv3 tunnel in the host route of the terminal;

The encapsulating unit is configured to send the L2TPv3 tunnel obtained by the tunnel obtaining unit to the LAC by performing the Layer 2 information encapsulation and the L2TPv3 encapsulation.

Embodiments of the present invention also provide a system for implementing wholesale of DHCP user services, including LAC and LNS.

The LAC, when receiving the data packet sent by the terminal, performs the L2TPv3 encapsulation on the data packet, and sends the encapsulated data packet to the L2TP network service device LNS through the L2TPv3 tunnel corresponding to the terminal. And receiving the response packet sent by the LNS through the L2TPv3 tunnel, and decapsulating the response packet to send to the terminal; The LNS is configured to perform L2TPv3 tunnel decapsulation on the packet received from the LAC, and search the routing table according to the destination IP address of the decapsulated data packet, and forward the data packet to the destination device; When the response packet is sent by the device, the response packet is encapsulated in the Layer 2 information and encapsulated in the L2TPv3 tunnel, and then sent to the LAC through the obtained L2TPv3 tunnel.

Compared with the prior art, the embodiment of the invention has the following advantages:

The LAC device maps the packets of the terminal to the L2TPv3 tunnel and transmits the packets to the remote LNS device through the L2TPv3 tunnel. The LNS device interacts with the network to implement the wholesale of DHCP users. In the embodiment of the present invention, the L2TPv3 tunnel can be established in a common IP network, and has the advantages of realizing the single order and low networking cost. DRAWINGS

1 is a schematic diagram of a network for implementing static service wholesale using a VPLS network in the prior art;

2 is a flow chart of a method for implementing wholesale of a DHCP user service in an embodiment of the present invention;

3 is a schematic diagram of a network networking in an embodiment of the present invention;

4 is a flow chart of assigning an address to a terminal through a DHCP protocol in an embodiment of the present invention;

5 is a data forwarding flow diagram of a terminal accessing an Internet network in an embodiment of the present invention;

6 is a schematic diagram of a LAC structure for implementing DHCP user service wholesale in an embodiment of the present invention;

FIG. 7 is a schematic structural diagram of another LAC for implementing wholesale of a DHCP user service according to an embodiment of the present invention; FIG.

FIG. 8 is a schematic structural diagram of an LNS for implementing wholesale of a DHCP user service according to an embodiment of the present invention. detailed description

An embodiment of the present invention provides a method for implementing wholesale of a DHCP user service, as shown in the figure.

2, including the following steps:

Step s201: When receiving the data packet sent by the terminal, the LAC encapsulates the data packet in L2TPv3.

Step s202: The LAC acquires an L2TPv3 tunnel corresponding to the terminal, and sends the encapsulated data to the LNS (L2TP Network Server, L2TP network server) through the corresponding L2TPv3 tunnel.

Step s203: The LAC receives the response packet sent by the LNS through the L2TPv3 tunnel. Step s204: The LAC decapsulates the response packet and sends the response packet to the terminal.

The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Figure 3 shows the networking diagram of the wholesale of DHCP user services.

After the DHCP terminal is started, the process of assigning an address to the terminal through the DHCP protocol is as shown in FIG. 4, and includes the following steps:

Step s301: The DHCP terminal sends a DHCP session request message, where the Option 60 information carries the user domain information.

Step s302: The AN (Access Network, access network) listens to the user's DHCP session request message. Optionally, the AN can add the physical line Option 82 information to the message.

Step s303: The AN sends a DHCP session request packet carrying Option 60 information and Option 82 information to the LAC.

Step s304: The LAC performs authentication according to the Option 82 information to the AAA (Access Authentication Authorization, Access Authentication, Authorization) server, and then continues after the authentication is passed. This step is optional.

Step s305: The LAC dynamically maps the DHCP session request packet of the terminal to the L2TPv3 tunnel and sends the packet to the LNS.

Specifically, the L2TPv3 tunnel may be statically established in advance or may be rooted by the LAC. Dynamically triggered establishment based on user session. The LAC maps the DHCP packets of the terminal to the L2TPv3 tunnel based on the terminal access interface and the VLAN to which the terminal belongs. The mapping between the access interface of the terminal, the VLAN to which the terminal belongs, and the L2TPv3 tunnel can be established in advance, whether the tunnel is dynamically established or dynamically. The session in the L2TPv3 tunnel is dynamically triggered by the DHCP session. The LAC saves the Option 82 and Option 60 information in the user session.

Step s306: The LNS selects a DHCP server and requests the DHCP server to allocate an address for the DHCP terminal.

Specifically, after receiving the DHCP session request message transmitted by the L2TPv3 tunnel, the LNS first obtains the gateway address GiAddr corresponding to the DHCP terminal according to the domain information of the DHCP terminal carried in the Option 60 option in the packet, and then according to Option 60. The DHCP session request packet of the terminal is forwarded to different DHCP servers to request an address for the DHCP terminal. The LNS records the Layer 2 information of the DHCP terminal (the MAC address, VLAN, or QinQ information accessed by the user) for subsequent DHCP. Protocol response 4 (including DHCP OFFER packets and DHCP Ack packets) and data packet encapsulation.

Step s307: The DHCP server allocates a corresponding address pool network segment address to the DHCP terminal according to GiAddr.

Step s308: The LNS receives the DHCP response message sent by the DHCP server, that is, the address allocation of the DHCP server is successful, and the corresponding information is recorded.

Specifically, the LNS generates a host route to the user terminal (that is, a 32-bit mask route, and performs an exact match search according to the IP address of the terminal, the host route corresponds to the network segment route, and the network segment route is searched according to the IP network segment) The access interface of the DHCP terminal is the L2TPv3 tunnel inbound interface. The Layer 2 information of the DHCP terminal is recorded in the forwarding entry of the terminal, and is used to forward the data packet sent to the DHCP terminal.

Step s309: The LAC receives the response packet sent by the LNS, and records the corresponding information. Specifically, the LAC records the L2TPv3 tunnel ID and the session ID, the Layer 2 encapsulation information, and the binding relationship of the DHCP terminal access interface, and is used to forward the data packet sent to the DHCP terminal. The address of the DHCP terminal and the L2TPv3 tunnel ID and session are generated. Correspondence relationship of the ID, used to forward the packet sent from the DHCP terminal to the network side; The response packet of the network side is sent to the DHCP terminal through the access aggregation network.

Step s310: The DHCP terminal obtains an IP address assigned by the network side, and can access the Internet.

After obtaining the address assigned by the network side, the data forwarding process when the terminal accesses the Internet network is as shown in FIG. 5, and includes the following steps:

Step s401: The DHCP terminal sends data to the network side.

Step s402: The LAC receives the data packet sent by the DHCP terminal, and encapsulates the Layer 2 data packet in the L2TPv3, and maps the encapsulated Layer 2 data packet to the corresponding L2TPv3 according to the source MAC address and the source IP address of the DHCP terminal. The tunnel is sent to the LNS.

Step s403: The LNS performs L2TPv3 tunnel decapsulation, and searches the routing table according to the destination IP address of the data packet, and forwards the data packet of the DHCP terminal to the destination device of the Internet network according to the routing table.

Step s404: The LNS receives the response message sent by the destination device to the DHCP terminal, and first searches the routing table to obtain the host route of the DHCP terminal, and the outbound interface of the route is an L2TPv3 tunnel. The LNS encapsulates the response packet sent by the destination device with Layer 2 information, and then encapsulates it in L2TPv3 and sends it to the LAC.

Step s405: The LAC finds the access interface of the DHCP terminal according to the ID of the L2TPv3 tunnel and the session ID, terminates the L2TPv3 tunnel encapsulation, and forwards the decapsulated response message from the interface.

Step s406: The DHCP terminal receives the response packet returned by the destination device. In addition, the LNS also stores the gateway address corresponding to each user terminal. When the user terminal performs the operation of pinging the address pool gateway, the LNS responds to the ping operation. The mutual access between the DHCP wholesale users is also performed by the LNS. The data packets are not exchanged on the LAC. Specifically, the LNS has a routing table, which can be forwarded according to the destination address of the data packet and the routing table. Therefore, Packet interaction between DHCP wholesale users can be performed through the LNS without directly interacting on the LAC.

The fault detection and recovery measures using L2TPv3 are as follows:

In order to real-timely sense the user terminal access and aggregate network status, you can pass the LAC. Enable ARP (Address Resolution Protocol) detection. When the user terminal detects that the user terminal times out, the LAC sends a session teardown message to the LNS, and the LNS deletes the user entry information. If the user terminal times out after the timeout due to a line interruption, the line state between the LAC and the user terminal is restored. If the LAC receives the data packet of the user terminal, the LAC searches for the saved Option 82 and Option 60 information, and then generates the DHCP protocol packet. The LAC sends the L2TPv3 tunnel to the LNS to re-apply the address to establish the user entry. This process is equivalent to the initial session initiation process of the DHCP terminal.

After receiving the DHCP response packet sent by the LNS, the LAC generates a user forwarding entry, that is, the binding relationship between the L2TPv3 tunnel ID and the session ID, the Layer 2 encapsulation information, and the access interface, so that the user terminal can access the Internet.

If the L2TP tunnel is down, if the ARP probe does not time out on the LAC, the LAC must be able to send DHCP packets to allow the LNS device to re-establish user entry information after the L2TPv3 tunnel is re-up.

In addition, the RADIUS (Remote Authentication Dial In User Service) supports the extension of the L2TP attribute. The RADIUS can deliver the tunnel type (64), the L2TP group name (81), and the LAC source address (66). Attributes of the LNS address (67), the tunnel name (90), the tunnel password (69), and the tunnel identifier (82). The RADIUS server delivers the L2TP tunnel attribute, which enables the LAC and LNS devices to be zero-configured. Manage network devices for easy network management.

When the ISP is configured to configure a new address pool, you do not need to change the configuration of the LAC that represents the NSP network resources. You only need to change the configuration information on the LNS device. The user management is completely controlled by the ISP to implement the real DHCP user wholesale.

With the method provided by the embodiment of the present invention, the LAC device maps the packet of the terminal to the L2TPv3 tunnel, and transmits the packet to the remote LNS device through the L2TPv3 tunnel, and the LNS device implements interaction with the network, thereby implementing the service of the DHCP user. wholesale. In the embodiment of the present invention, the L2TPv3 tunnel can be established in a common IP network, and has the advantages of realizing the single order and low networking cost. An embodiment of the present invention further provides a system for implementing wholesale of a DHCP user service, and a schematic structural diagram thereof is shown in FIG. 3, where:

When receiving the data packet sent by the terminal, the LAC encapsulates the data packet in L2TPv3; and sends the encapsulated data packet to the L2TP network service device LNS through the L2TPv3 tunnel corresponding to the terminal; A response packet sent by the L2TPv3 tunnel, and the response packet is decapsulated and sent to the terminal.

The LNS is configured to perform L2TPv3 tunnel decapsulation on the packet received from the LAC, and then search the routing table according to the destination IP address of the decapsulated data packet to forward the data packet to the destination device. The response packet is encapsulated in Layer 2 information according to the Layer 2 information of the terminal, and is encapsulated in L2TPv3 and sent to the LAC through the obtained L2TPv3 tunnel.

Specifically, the structure of the LAC in the system is as shown in FIG. 6, and includes:

The encapsulating unit 11 is configured to perform L2TPv3 encapsulation on the data packet when receiving the data packet sent by the terminal;

The tunnel obtaining unit 12 is configured to obtain an L2TPv3 tunnel corresponding to the terminal, and send the data packet encapsulated by the encapsulating unit 11 to the L2TP network service device LNS through the corresponding L2TPv3 tunnel;

The response message receiving unit 13 is configured to receive a response sent by the LNS through the L2TPv3 tunnel;

The decapsulation unit 14 is configured to decapsulate the response packet received by the response message receiving unit 13 and send it to the terminal.

Specifically, the structure of another LAC in the system is as shown in FIG. 7, and includes a packaging unit 11, a tunnel obtaining unit 12, a response message receiving unit 13 and a decapsulation unit 14, and further includes:

The first storage unit 15 is configured to store the correspondence between the address of the DHCP terminal recorded in the process of allocating the DHCP address for the terminal and the L2TPv3 tunnel ID and the session ID; and provide the correspondence to the tunnel obtaining unit 12.

The second storage unit 16 is configured to store the L2TPv3 tunnel ID and the session ID, the second layer encapsulation information, and the terminal access interface recorded in the process of allocating the DHCP address to the terminal. Corresponding relationship; and providing the correspondence to the decapsulation unit 14.

The tunnel mapping unit 17 is configured to receive, according to the access interface of the terminal, the VLAN to which the terminal belongs, and the access interface of the pre-established terminal, the VLAN to which the terminal belongs, and the L2TPv3 tunnel. Corresponding relationship, mapping the DHCP session request of the terminal into the corresponding L2TPv3 tunnel.

The offline detection unit 18 is configured to send a session teardown message to the LNS when the terminal times out offline;

The analog message sending unit 19, when receiving the data message of the timeout offline terminal again, simulates generating a DHCP session request message according to the information of the terminal, and sends the message to the LNS through the L2TPv3 tunnel, and re-assigns the address to the terminal. Specifically, the structure of the LNS in the system is as shown in FIG. 8, and includes:

The decapsulation unit 21 is configured to perform L2TPv3 tunnel decapsulation on the received packet, and the forwarding unit 22 is configured to decapsulate the data packet according to the decapsulation unit 21.

The IP looks up the routing table and forwards the data packet to the destination device.

The tunnel obtaining unit 23 is configured to obtain an outbound interface L2TPv3 tunnel in the host route of the terminal when receiving the response packet;

The encapsulating unit 24 is configured to perform the Layer 2 information encapsulation of the response packet according to the Layer 2 information of the terminal, and send the L2TPv3 tunnel obtained by the tunnel obtaining unit 23 to the LAC after performing the L2TPv3 encapsulation.

The LAC also includes:

The third storage unit 25 is configured to record the host route of the terminal and the layer 2 information of the terminal in the process of allocating the DHCP address to the terminal, and provide the information to the tunnel obtaining unit 23 and the encapsulating unit 24. With the system and device provided by the embodiment of the present invention, the LAC device maps the packet of the terminal to the L2TPv3 tunnel, and transmits the packet to the remote LNS device through the L2TPv3 tunnel, and the LNS device implements interaction with the network, thereby implementing the DHCP user. Business wholesale. In an embodiment of the present invention, the L2TPv3 tunnel can be established in a common IP network, Achieve the advantages of single order and low network cost.

Through the description of the above embodiments, those skilled in the art can clearly understand that the present invention can be implemented by hardware, or can be implemented by means of software plus necessary general hardware platform, and the technical solution of the present invention. It can be embodied in the form of a software product that can be stored in a non-volatile storage medium (which can be a CD-ROM, a USB flash drive, a mobile hard disk, etc.), including a number of instructions for making a computer device (may It is a personal computer, a server, or a network device, etc.) that performs the methods described in various embodiments of the present invention.

In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the scope of 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.

Claims

Rights request

A method for implementing a dynamic host configuration protocol for a DHCP user service wholesale, characterized in that:

Receiving the data packet sent by the terminal, performing the L2TPv3 encapsulation on the data packet, obtaining the L2TPv3 tunnel corresponding to the terminal, and sending the encapsulated data packet to the L2TP network service device LNS through the corresponding L2TPv3 tunnel ;

Receiving a response packet sent by the LNS through the L2TPv3 tunnel;

The method for implementing the wholesale of the DHCP user service according to claim 1, wherein the obtaining the L2TPv3 tunnel corresponding to the terminal specifically includes:

Obtaining an L2TPv3 tunnel corresponding to the terminal according to the correspondence between the address of the terminal and the L2TPv3 tunnel ID and the session ID.

The method for implementing the wholesale of the DHCP user service according to claim 1, wherein the sending the response packet to the terminal after decapsulating the packet includes: transmitting an L2TPv3 tunnel according to the response packet And the corresponding relationship between the ID and the session ID, the layer 2 package information, and the terminal access interface, the access interface of the terminal is obtained, and the decapsulated response message is sent to the terminal by using the access interface.

The method for implementing the wholesale of the DHCP user service according to claim 1, wherein before receiving the response message sent by the LNS through the L2TPv3 tunnel, the method further includes:

The LNS performs L2TPv3 tunnel decapsulation on the received data packet, searches the routing table according to the destination IP address of the decapsulated data packet, and forwards the data packet to the destination device of the data packet.

When the LNS receives the response packet sent by the destination device, the LNS obtains the outbound interface L2TPv3 tunnel in the host route of the terminal;

And the LNS sends the response packet to the LAC through the obtained L2TPv3 tunnel after performing Layer 2 information encapsulation and L2TPv3 encapsulation.

5. The method for implementing wholesale of a DHCP user service according to claim 4, characterized in that The method further includes: the LNS records a host route of the terminal, and Layer 2 information of the terminal in a process of allocating a DHCP address to the terminal.

The method for implementing the DHCP user service wholesale according to claim 2, 3 or 5, wherein the process of assigning a DHCP address to the terminal specifically includes:

Receiving a DHCP session request message of the terminal;

And mapping the DHCP session request of the terminal into the L2TPv3 tunnel and sending the message to the LNS according to the Option 60 information in the DHCP session request packet of the terminal;

The LNS selects a DHCP server according to the Option 60 information of the terminal, and requests the DHCP server to allocate an address for the terminal.

Receiving, by the LNS, an address allocated by the DHCP server for the terminal, generating a host route to the terminal, and recording Layer 2 information of the terminal, and sending an address allocation success message to the LAC; The access interface of the terminal is an L2TPv3 tunnel ingress interface.

The LAC receives the response packet sent by the LNS, records the correspondence between the L2TPv3 tunnel ID and the session ID, the Layer 2 encapsulation information, and the terminal access interface; and records the correspondence between the address of the terminal and the L2TPv3 tunnel ID and the session ID, and then The terminal sends an address allocation success message.

The method for implementing the wholesale of the DHCP user service according to claim 6, wherein the step of the LAC mapping the DHCP session request packet of the terminal into the L2TPv3 tunnel includes:

Mapping the DHCP session request packet of the terminal into the corresponding interface according to the access interface of the terminal and the VLAN to which the terminal belongs, and the access interface of the pre-established terminal, the VLAN to which the terminal belongs, and the L2TPv3 tunnel. The L2TPv3 tunnel.

The method for implementing the wholesale of a DHCP user service according to claim 1, further comprising:

And detecting that the terminal times out the line, sending a session teardown message to the LNS, where the LNS deletes the entry information of the terminal;

When receiving the data message of the terminal again, according to the information of the terminal, the simulation student The DHCP session request packet is sent to the LNS through the L2TPv3 tunnel, and the terminal is allocated an address again.

An L2TP access centralized device LAC, comprising: an encapsulating unit, configured to perform L2TPv3 encapsulation on the data packet when receiving the data packet sent by the terminal;

The LAC according to claim 9, further comprising:

a first storage unit, configured to store a correspondence between an address of the DHCP terminal and an L2TPv3 tunnel ID and a session ID, and provide the correspondence to the tunnel obtaining unit.

The LAC according to claim 9, further comprising:

And a second storage unit, configured to store an ID of the L2TPv3 tunnel and a session ID, a layer 2 package information, and a correspondence between the terminal access interfaces, and provide the corresponding relationship to the decapsulation unit.

The LAC according to claim 9, further comprising: a tunnel mapping unit, configured to receive, according to the access interface of the terminal, a VLAN to which the terminal belongs, and a pre-received The mapping between the access interface of the terminal, the VLAN to which the terminal belongs, and the L2TPv3 tunnel is mapped to the corresponding L2TPv3 tunnel.

The LAC according to claim 9, further comprising:

The offline detection unit is configured to send a session teardown message to the LNS when the terminal times out offline;

The analog message sending unit is configured to: when receiving the data message of the timeout offline terminal again, simulate generating a DHCP session request message according to the information of the terminal, and pass the The L2TPv3 tunnel is sent to the LNS, and the terminal is allocated an address again.

An L2TP network server LNS device, comprising: a decapsulation unit, configured to perform L2TPv3 tunnel decapsulation on the received data packet; and a forwarding unit, configured to decapsulate the data according to the decapsulation unit The destination IP address of the packet is used to find a routing table, and the data packet is forwarded to the destination device.

The LNS according to claim 14, further comprising:

And a third storage unit, configured to record, in the process of allocating a DHCP address for the terminal, a host route of the terminal, and Layer 2 information of the terminal, and provide the information to the tunnel obtaining unit and the encapsulating unit.

16. A system for implementing wholesale of DHCP user services, including a LAC and an LNS, wherein

The LAC, when receiving the data packet sent by the terminal, performs the L2TPv3 encapsulation on the data packet, and sends the encapsulated data packet to the L2TP network service device LNS through the L2TPv3 tunnel corresponding to the terminal. And receiving the response packet sent by the LNS through the L2TPv3 tunnel, and decapsulating the response packet to send to the terminal;

The LNS is configured to perform L2TPv3 tunnel decapsulation on the packet received from the LAC, and search the routing table according to the destination IP address of the decapsulated data packet, and forward the data packet to the destination device; When the response packet is sent by the device, the response packet is encapsulated in the Layer 2 information and encapsulated in the L2TPv3 tunnel, and then sent to the LAC through the obtained L2TPv3 tunnel.