CN101035082B - Fragmented message reassembly method and interface board - Google Patents

Abstract

The invention discloses a fragmented message recombination method, which includes: pre-configuring the same recombination interface board selection principle on each interface board of the receiving device, when the interface board on the receiving device receives a fragment, the interface board determines the same This fragment belongs to all the interface boards that all the fragments of the same message may reach, according to the recombination interface board selection principle, select an interface board in the determined interface boards as the recombination interface board, and send the received fragmentation Go to the reassembly interface board for reassembly. The invention also discloses an interface board, which includes: a fragmentation receiving module and a recombination interface board determination module. The invention enables fragments of different messages to be distributed to different interface boards for reorganization, greatly speeds up the speed of recombination of messages, and reduces the burden of the main control board.

Description

Fragmented message reassembly method and interface board

technical field

The invention relates to the technical field of data transmission, in particular to a fragmented message recombination method and an interface board.

Background technique

Fragmented packets are very common packets in Internet Protocol (IP) networks. When the packet length exceeds the maximum sending unit of the interface, the packet must be fragmented and then sent through the interface; when the packet reaches the destination address, the destination device is responsible for collecting all the fragments of the packet and The offset of the text is reorganized and restored to its original state.

In a distributed environment, for packets that are not transmitted in load sharing mode, the packets will be concentrated on one interface to reach the destination device; while for packets transmitted in load sharing mode, the packets may be dispersed in different interfaces to reach the destination device .

A distributed environment usually includes boards with two roles: the main control board and the interface board. The interface board is responsible for data communication with the outside; the main control board is responsible for collecting control data and sending control information to the interface board. Figure 1 shows a schematic diagram of message reassembly when fragments reach the destination device from an interface. As shown in Figure 1, all fragments of a message: fragments 1 to 4 arrive at the destination device from interface board 1 Then the interface board 1 sends the fragments 1 to 4 to the main control board, and the main control board reassembles the fragments 1 to 4 into a complete message. Figure 2 shows a schematic diagram of message reassembly when fragments reach the destination device from multiple interfaces. As shown in Figure 2, all fragments of a message: fragments 1 to 4 pass through two interface boards: interface Boards 1 and 2 reach the destination device, where slices 1 and 3 reach the destination device through interface board 1, and slices 2 and 4 reach the destination device through interface board 2. Similarly, interface board 1 will divide slices 1 and 3, interface board 2 Send fragments 2 and 4 to the main control board, and the main control board reassembles fragments 1 to 4 into a complete message. From Figure 1 and Figure 2, it can be seen that in order to ensure that the fragmented packets arriving at the destination device can be processed correctly, the interface board will The fragments are sent to the main control board, and the main control board performs packet reassembly processing.

As mentioned above, in the prior art, for all fragments of a message, no matter whether the fragments arrive at the destination device from only one interface or from multiple interfaces, the interface board that receives the fragments will Sent to the main control board for reassembly. Obviously, this will increase the burden on the main control board, thereby reducing the packet reassembly speed.

Contents of the invention

The invention provides a fragmented message recombination method and an interface board to improve the recombination speed of the fragmented message.

Technical scheme of the present invention is realized like this:

A fragmented message reassembly method, in which the same reassembly interface board selection principle is pre-configured on each interface board of the receiving device, including:

The interface board on the receiving device receives the fragment, determines all the possible interface boards that all fragments belonging to the same message as the fragment may arrive, and selects an interface among the determined interface boards according to the recombination interface board selection principle As a reassembly interface board, the received fragments are sent to the reassembly interface board for reassembly.

The said determination of all interface boards that all fragments that belong to the same message as the fragment may arrive includes: the interface board searches for the route corresponding to the source IP address of the fragment received by itself in the routing table saved by the receiving device, and sends the The interface board corresponding to all outgoing interface information of the route is used as the interface board that all fragments belonging to the same message as the fragment may arrive.

The selection principle of the recombined interface board is: use the interface board with the smallest board number as the recombined interface board,

The interface board selecting an interface board from the determined interface boards as the recombination interface board includes: selecting the interface board with the smallest board number among the determined interface boards as the recombination interface board;

Alternatively, the selection principle of the reconfiguration interface board is: use the interface board with the smallest load as the recombination interface board,

The interface board selecting an interface board as the recombined interface board from the determined interface boards includes: the interface board selects the interface board with the smallest load among the determined interface boards according to the load information of each interface board sent by the main control board recently. The interface board is used as a recombination interface board;

Alternatively, the selection principle of the reassembly interface board is: perform a hash operation on the source IP address and/or destination IP address and/or protocol number carried by the fragment, and use the interface board corresponding to the hash operation result as the reassembly interface board,

Selecting an interface board as a recombination interface board from the determined interface boards by the interface board includes: the interface board performs a hash operation on the source IP address and/or destination IP address and/or protocol number of the fragment, and the hash operation The result is mapped to one of the determined interface boards, and the interface board is used as the recombined interface board.

Pre-configuring on the receiving device the correspondence between fragmentation path information and reassembly mode information supported by fragmentation,

After the interface board on the receiving device receives the fragment, before determining all the interface boards to which all the fragments belonging to the same message as the fragment may arrive, the method further includes: the receiving device judges the corresponding relationship according to its own configuration. Fragmentation supports centralized reorganization or decentralized reorganization. If centralized reassembly is supported, the fragment will be sent to the main control board for reorganization, and this process will end; if decentralized reassembly is supported, it will be determined that the fragment belongs to the same message. All interface boards that all fragments may reach.

The fragment path information is: fragment source IP address and/or destination IP address and/or protocol number.

The receiving device is: a destination device where the fragment arrives, or a forwarding device that forwards the fragment and supports virtual fragment reassembly.

An interface board, comprising:

The fragmentation receiving module, after receiving the fragmentation, sends the fragmentation information to the reorganization interface board determination module, and sends the fragmentation to the interface board corresponding to the identification according to the reorganization interface board identification sent by the reorganization interface board determination module;

The recombination interface board determination module receives the fragmentation information sent by the fragmentation receiving module, determines all the possible interface boards that all fragments belonging to the same message as the fragmentation information corresponding to the fragmentation information may reach, and selects according to the pre-configured recombination interface board In principle, one of the determined interface boards is selected as the reassembly interface board, and the identifier of the reassembly interface board is sent to the fragmentation receiving module.

The recombination interface board determination module includes:

The routing search module receives the source IP address sent by the fragment receiving module, searches for the route corresponding to the source IP address in the routing table saved by itself, and sends the outgoing interface information of the route to the reorganization interface board selection module,

The recombination interface board selection module receives the outgoing interface information sent by the routing search module, determines the interface board identification corresponding to the outgoing interface information, and selects among the interface boards corresponding to the interface board identification according to the pre-configured recombination interface board selection principle An interface board is used as a reorganization interface board, and the recombination interface board identifier is sent to the fragmentation receiving module;

Moreover, the fragment receiving module sends the source IP address of the fragment to the routing search module after receiving the fragment.

The interface board further includes: a fragmentation reorganization module, which receives fragments sent by other interface boards and its own fragmentation receiving module, and performs reorganization processing on all fragments,

Moreover, when the fragment receiving module detects that the reorganized interface board identifier sent by the reassembled interface board selection module is its own interface board identifier, it sends the received fragment to the fragment reassembled module.

The interface board further includes: a recombination mode configuration module, which stores the corresponding relationship between the fragmentation path information configured by the user and the recombination mode information supported by the fragmentation;

And, after the fragmentation receiving module receives the fragmentation, it inquires the reorganization mode supported by the fragmentation from the reorganization mode configuration module according to the path information of the fragmentation. send the fragments to the main control board; if it is found that the decentralized reorganization mode is supported, the fragment information is sent to the reorganization interface board determination module.

Compared with the prior art, in the present invention, the same recombination interface board selection principle is pre-configured on each interface board of the receiving device. When the interface board on the receiving device receives the fragment, it determines that the fragment belongs to the same message All interface boards that all fragments may reach, according to the selection principle of the reassembly interface board, select an interface board among the determined interface boards as the reassembly interface board, and send the received fragments to the reassembly interface board for reassembly , so that the fragments of different messages can be distributed to different interface boards for reassembly, which greatly speeds up the speed of message reassembly and reduces the burden on the main control board.

Description of drawings

FIG. 1 is a schematic diagram of packet reassembly when fragments arrive at a destination device from an interface in the prior art;

Figure 2 shows the process of packet reassembly when fragments arrive at the destination device from multiple interfaces in the prior art

FIG. 3 is a flow chart of reassembling fragmented packets provided by Embodiment 1 of the present invention;

FIG. 4 is a flow chart of reassembling fragmented packets provided by Embodiment 2 of the present invention;

FIG. 5 is a schematic structural diagram of an interface board for recombining fragmented packets provided by an embodiment of the present invention;

Fig. 6 is the composition mode 1 of the recombined interface board selection module in the interface board provided by the embodiment of the present invention;

Fig. 7 shows the second composition mode of the recombined interface board selection module in the interface board provided by the embodiment of the present invention;

Fig. 8 is the composition mode 3 of the recombined interface board selection module in the interface board provided by the embodiment of the present invention;

FIG. 9 is a schematic diagram of packet reassembly when fragments arrive at a destination device from an interface in an embodiment of the present invention;

FIG. 10 is a schematic diagram of packet reassembly when fragments arrive at a destination device from multiple interfaces in an embodiment of the present invention.

Detailed ways

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

Fig. 3 is the flowchart of reorganizing the fragmented message provided by Embodiment 1 of the present invention, as shown in Fig. 3, its specific steps are as follows:

Step 301: Configure the same recombination interface board selection principle on each interface board of the receiving device.

The selection principle of the reassembly interface board can be: among all the interface boards that may receive fragments, use the interface board with the smallest board number as the reassembly interface board; or, among all the interface boards that may receive fragments, use the interface board with the smallest load The interface board is used as a reconfiguration interface board. At this time, the main control board needs to periodically send the load information of all interface boards to each interface board; or, for the fragmented source IP address and/or destination IP address and/or protocol number Perform a hash (hash) operation, and use the interface board corresponding to the result of the hash operation among all the interface boards that may receive the fragment as the recombined interface board.

Step 302: After receiving the fragment, the interface board on the receiving device looks up the route corresponding to the source IP address carried by the fragment in the routing table saved by itself.

Step 303: the interface board judges whether the search result is an equivalent route, and if so, executes step 304; otherwise, executes step 308.

In the embodiment of the present invention, equal-cost routes refer to the existence of more than one route from the source device to the receiving device, and these routes are called equal-cost routes; non-equivalent routes refer to the existence of only one route from the source device to the receiving device. a route.

Step 304: The interface board judges whether all outgoing interfaces of the found equivalent routes are located on one interface board, and if so, executes step 308; otherwise, executes step 305.

Each interface board stores the corresponding relationship between the outbound interface information and the interface board number, and the interface board can determine whether all outbound interfaces of the found equal-cost routes are located on one interface board according to the corresponding relationship.

Step 305: The interface board selects an interface board as the reconfiguration interface board from the interface boards corresponding to all outgoing interfaces of the found equal-cost routes according to the pre-configured recombination interface board selection principle.

The selection principle of the reassembly interface board is: among all the interface boards that may receive fragments, the interface board with the smallest board number is used as the reassembly interface board. Among the interface boards corresponding to all outgoing interfaces, select the interface board with the smallest board number as the reconfiguration interface board.

In particular, since the routing table stored on the receiving device and the source device or intermediate forwarding device that sent the fragment may be inconsistent, it may cause that the interface board that receives the fragment does not correspond to all the outgoing interfaces of the found equivalent routes Any one of the interface boards, at this time, considering that other interface boards on the receiving device will not know that the interface board will receive the fragment according to the routing table, therefore, all the interface boards that receive the fragment will still use the Based on the interface board determined by the equal-cost route, determine the reconfiguration interface board. For example: set the interface board with the smallest board number in advance as the recombination interface board, and set a message to include 4 fragments: fragments 1 to 4, of which: fragments 1 and 3 reach the receiving device through interface board 1, and fragments 2 and 4 reach the receiving device through interface board 2, and the outbound interface information in the equivalent route corresponding to the source IP addresses of the four fragments on the receiving device indicates that the outbound interface of the fragment of the message is located on the interface board 2 and 3, interface boards 1 and 2 select the interface board with the smallest board number among interface boards 2 and 3: interface board 2 is used as the reconfiguration interface board.

The selection principle of the reassembly interface board is: among all the interface boards that may receive fragments, the interface board with the smallest load is used as the reassembly interface board. For the load information of the interface board, among the interface boards corresponding to all the outbound interfaces of the found equal-cost routes, select the interface board with the smallest load as the interface board for reassembly.

When reorganizing the interface board selection principle is: perform hash operation on the source IP address and/or destination IP address and/or protocol number of the fragment, and among all the interface boards that may receive the fragment, the When the interface board is used as a reassembly interface board, the interface board that receives the fragments only needs to perform hash operations on the source IP address and/or destination IP address and/or protocol number of the fragments, and then map the hash operation results to the found One of the interface boards corresponding to all the outbound interfaces of the equal-cost route is used as the recombination interface board. For example: suppose the outbound interface of the equivalent route found by the interface board based on the source IP address of the fragment is located on three interface boards: interface boards 2 to 4, set the source IP address of the fragment to 1.2.3.4, and the destination IP address is 2.3.4.5, then each interface board receiving the fragment performs hash operation on the source IP address and destination IP address, hash=(1+2+3+4+2+3+4+5)%3= 0, it is determined that interface board 2 is a reconfigured interface board, where a in %a indicates the total number of interface boards corresponding to the outbound interfaces of the found equal-cost routes.

Step 306: the interface board sends the received fragments to the reassembly interface board.

If the reorganized interface board is itself, the interface board does not need to send fragments.

Step 307: The reassembly interface board receives the fragments sent by other interface boards, and reassembles all the fragments according to the fragments and the offsets in the fragments received by itself, and the process ends.

Since the reassembly interface boards configured on each interface board have the same selection principle, for the same message, the reassembly interface boards determined by the interface boards that receive different fragments of the message will be the same, ensuring that the reassembly interface boards will get All fragments of the message, so that the message reassembly can be performed reliably.

After the reassembly interface board completes the reassembly of fragmented packets, it sends the reassembled packets to the upper-layer entity for processing.

Step 308: the interface board determines that it will receive all fragments of the packet, and reassembles the received fragments.

Specifically, when the interface board determines that the route found based on the source IP address of the fragment is a non-equivalent route, or that the found route is an equal-cost route but all outgoing interfaces are located on only one interface board, if the If the interface board corresponding to the non-equivalent route or the outbound interface of the equal-cost route is not the same interface board as itself, send the fragment to the non-equivalent route or the outbound interface of the equal-cost route Reassemble on the corresponding interface board.

In addition, in practical applications, when the interface board is reassembled, the selection principle is: perform a hash (hash) operation on the source IP address and/or destination IP address and/or protocol number of the fragment, and all In the interface board, when the interface board corresponding to the hash operation result is used as the recombination interface board, after the interface board receives the fragment, it does not need to search the routing table, and directly checks the source IP address and/or destination IP address and /or the protocol number, etc. are hashed, and then the result of the operation is mapped to an interface board number, and the interface board corresponding to the interface board number is used as the recombined interface board. For example: if the receiving device has 4 interface boards in total: interface boards 0 to 3, if the source IP address of the fragment received by the interface board is: 1.2.3.4, the hash operation is performed on the source IP address: hash=(1+ 2+3+4) %4=2, the interface board 2 is used as the recombined interface board, wherein a in %a represents the total number of interface boards on the receiving device.

It can be seen that the embodiment shown in FIG. 3 is not only applicable to packets transmitted in a load sharing manner, but also applicable to packets not transmitted in a load sharing manner.

In addition, users can know in advance which paths will transmit packets in load sharing mode and which paths will not transmit packets in load sharing mode according to the network deployment environment. The distributed reorganization method mentioned in the embodiment shown in FIG. Packets are reassembled in reassembly mode. In this way, the user can configure the message path information such as: source IP address and/or destination IP address and/or protocol number, etc. The source IP address and/or destination IP address and/or protocol number of the fragment, etc., determine whether to adopt the centralized reorganization method or the decentralized reorganization method for reorganization, and if the centralized reorganization method is adopted, the fragment is sent to the main control board for reorganization; If the distributed reorganization method is adopted, the method shown in Figure 3 is used for reorganization.

Fig. 4 is the flowchart of reorganizing the fragmented message provided by Embodiment 2 of the present invention, as shown in Fig. 4, the specific steps are as follows:

Step 401: Pre-configure on the receiving device the correspondence between path information such as source IP address and/or destination IP address and/or protocol number and reassembly mode information, and configure the same reassembly interface board selection principle on each interface board of the device.

Reorganization methods include: centralized reorganization and decentralized reorganization.

The correspondence between the source IP address and/or the destination IP address and/or the protocol number and the reassembly mode information may be configured in an access control list (ACL).

Step 402: The interface board receives the fragment, and judges whether the fragment supports the centralized reorganization method or the decentralized reorganization method according to the source IP address and/or destination IP address and/or protocol number of the fragment, if it supports the centralized reorganization method , execute step 403; if support the distributed reorganization mode, execute step 404.

Step 403: the interface board sends the fragment to the main control board, and the main control board performs fragment reorganization processing, and the process ends.

Steps 404-410 are the same as steps 302-308.

It should be pointed out that the device mentioned in the embodiment of the present invention may be a destination device where a message arrives, or a forwarding device that forwards a message and supports virtual fragment reassembly. Since the forwarding device may support services such as network address translation (NAT), IP packet security inspection (IPSec), and dynamic firewall (ASPF), when the forwarding device receives a fragmented packet, it must perform the above-mentioned service processing on each fragment ;Among all fragments of a message, only the first fragment sent by the source device, that is: the first fragment contains source/destination port number information, and when performing the above business processing on each fragment, use Therefore, it must be ensured that all fragments can be processed on the same interface board, so that the interface board can obtain the source/destination port number information from the first fragment and use it for the above services of all fragments deal with. The situation of concentrating the fragments on the same interface board due to the need to perform the above business processing on the fragments is called virtual fragment reorganization.

FIG. 5 is a schematic structural diagram of an interface board for fragmented message reassembly provided by an embodiment of the present invention. As shown in FIG. 5 , it mainly includes: a fragmented receiving module 51, a route search module 52 and a reorganized interface board selection module 53, in:

Fragment receiving module 51: for after receiving fragment, the source IP address of this fragment is sent to routing search module 52; The interface board corresponding to the number of the reconfigured interface board.

Route lookup module 52: used to receive the source IP address sent by the fragmentation receiving module 51, search for the route corresponding to the source IP address in the routing table saved by itself, and send the outgoing interface information of the route to the reorganization interface board for selection Module 53.

Recombination interface board selection module 53: used to receive the outgoing interface information sent by the routing search module 52, determine the interface board number corresponding to the outgoing interface information, according to the recombination interface board selection principle pre-configured in itself, in the interface board number Among the corresponding interface boards, one interface board is selected as the reassembly interface board, and the number of the reassembly interface board is sent to the fragment receiving module 51 .

The interface board in the embodiment of the present invention may further include: a fragmentation reassembly module 54, configured to receive fragments sent by other interface boards and its own fragmentation receiving module 51, and reassemble all fragments. Moreover, when the fragmentation receiving module 51 detects that the reassembly interface board number sent by the reassembly interface board selection module 53 is its own interface board number, it sends the received fragmentation to the fragmentation reassembly module 54 .

The interface board in the embodiment of the present invention may further include: a reassembly mode configuration module 55, configured to store the correspondence between the user-configured source IP address and/or destination IP address and/or protocol number and reassembly mode information. And, after the fragmentation receiving module 51 receives the fragmentation, according to the source IP address and/or destination IP address and/or protocol number of the fragmentation, etc., query the reorganization method configuration module 55 supported by the fragmentation If it is inquired that the centralized reorganization method is supported, the received fragments are sent to the main control board;

In practical applications, the route lookup module 52 and the reassembly interface board selection module 53 may be collectively referred to as a reassembly interface board determination module.

In the interface board provided in the embodiment of the present invention, the reconfiguration interface board selection module 53 can have the following three composition modes:

Fig. 6 is the composition mode 1 of the recombined interface board selection module in the interface board provided by the embodiment of the present invention. As shown in Fig. 6, it mainly includes: an interface information storage module 5311 and a selection module 5312, wherein:

Interface information storage module 5311: for storing the corresponding relationship between interface information and interface board number.

Selection module 5312: used to receive the outbound interface information sent by the routing search module 52, query the interface board number corresponding to the outbound interface information from the interface information storage module 5311, and select a board among the interface boards corresponding to the interface board number The interface board with the smallest number is used as the reassembly interface board, and the reassembly interface board number is sent to the fragmentation receiving module 51.

Fig. 7 is the composition mode 2 of the recombined interface board selection module in the interface board provided by the embodiment of the present invention. As shown in Fig. 7, it mainly includes: an interface information storage module 5321, a load information receiving module 5322 and a selection module 5323, wherein :

Interface information storage module 5321: for storing the corresponding relationship between interface information and interface board number.

Load information receiving module 5322: Receive and store the corresponding relationship between each interface board number and load information sent by the main control board.

Selection module 5323: receive the outbound interface information sent by the route search module 52, query the interface board number corresponding to the outbound interface information from the interface information storage module 5321, and get the load corresponding to the interface board number from the load information receiving module 5322 According to the load information, select an interface board with the smallest load from the interface boards corresponding to the inquired interface board numbers as the reassembly interface board, and send the reassembly interface board number to the fragmentation receiving module 51 .

Fig. 8 is the composition mode 3 of the recombined interface board selection module in the interface board provided by the embodiment of the present invention. As shown in Fig. 8, it mainly includes: an interface information storage module 5331, a hash operation module 5332 and a selection module 5333, wherein :

Interface information storage module 5331: store the corresponding relationship between interface information and interface board number.

Hash operation module 5332: receiving information such as the source IP address and/or destination IP address and/or protocol number of the fragment sent by the fragmentation receiving module 51, for the IP address and/or destination IP address and/or protocol number and so on to carry out the hash operation, and send the hash operation result to the selection module 5333.

Selection module 5333: receive the outgoing interface information sent by the route search module 52, query the interface board number corresponding to the outgoing interface information from the interface information storage module 5331, receive the hash operation result sent by the hash operation module 5332, and use the hash The calculation result is mapped to an interface board number obtained from the query, and the interface board number is sent to the fragment receiving module 51 as the reassembled interface board number.

Two specific examples of applying Embodiment 1 of the present invention are given below:

Fig. 9 is a schematic diagram of packet reassembly when a fragment arrives at a destination device from an interface. As shown in Fig. 9, whenever the interface board 1 receives a fragment, it searches for the route corresponding to the source IP address of the fragment, and determines If the outbound interface information of the route only corresponds to interface board 1, it is determined that it is the reassembled interface board, and reassembles fragments 1 to 4 into complete packets according to the received offsets in fragments 1 to 4.

Figure 10 is a schematic diagram of message reassembly when fragments arrive at the destination device from multiple interfaces. As shown in Figure 10, interface board 1 and interface board 2 each receive a fragment and search for the source IP address of the fragment Corresponding route, confirm that the outbound interface information of the route corresponds to interface board 1 and 2, then select interface board 1 with the smallest board number as the reassembly interface board, interface board 2 sends the received fragments 2 and 4 to interface board 1, and the interface Board 1 reassembles fragments 1 to 4 into complete packets according to the offsets in fragments 1 and 3 received by itself and fragments 2 and 4 sent by interface board 2.

The above descriptions are only process and method embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (7)

1. A fragmented message reorganization method is characterized in that, the same recombination interface board selection principle is configured in advance on each interface board of the receiving device, including: After receiving the fragment, the interface board on the receiving device searches for the route corresponding to the source IP address of the fragment in the routing table saved by the receiving device. Located on the same interface board, then according to the recombination interface board selection principle, select an interface board from the interface boards corresponding to all outgoing interfaces of the equivalent route as the recombination interface board, and send the received fragments to the recombination interface board on reorganization. 2. The method according to claim 1, wherein the selection principle of the reorganization interface board is: the interface board with the smallest board number is used as the recombination interface board, and the interface board that receives the fragmentation is found in the equivalent route Among the interface boards corresponding to all the outbound interfaces, select the interface board with the smallest board number as the reconfiguration interface board; Or, the selection principle of the reorganization interface board is: the interface board with the smallest load is used as the recombination interface board, and the interface board that receives the fragmentation is based on the load information of each interface board sent by the main control board, and finds the equivalent Among the interface boards corresponding to all outgoing interfaces of the route, select the interface board with the smallest load as the reconfiguration interface board; Alternatively, the selection principle of the recombination interface board is: perform a hash operation on the source IP address and/or destination IP address and/or protocol number of the fragment, and map the hash operation result to all outgoing routes of the found equivalent routes. One of the interface boards corresponding to the interface is used as a reconfiguration interface board. 3. The method according to claim 1, characterized in that the corresponding relationship between fragmentation path information and fragmentation supported reassembly mode information is pre-configured on the receiving device, After the interface board on the receiving device receives the fragment, before searching for the route corresponding to the source IP address of the fragment in the routing table saved by the receiving device, it further includes: the receiving device judges according to the corresponding relationship configured by itself The fragment supports the centralized reorganization method or the decentralized reorganization method. If the centralized reorganization method is supported, the fragment is sent to the main control board for reorganization, and this process ends; if the decentralized reorganization method is supported, the route saved in the receiving device is executed. The action of looking up the route corresponding to the source IP address of the fragment in the table; The fragment path information is: fragment source IP address and/or destination IP address and/or protocol number. 4. The method according to claim 1, wherein the receiving device is: a destination device where fragments arrive, or a forwarding device that forwards fragments and supports virtual fragment reassembly. 5. A kind of interface board, it is characterized in that, comprises: Fragmentation receiving module, routing search module and recombination interface board selection module, wherein: Fragmentation receiving module, after receiving the fragmentation, sends the source IP address of the fragmentation to the route lookup module, and sends the fragmentation to the interface board corresponding to the identifier according to the reorganization interface board identification sent by the reorganization interface board selection module ; The routing search module receives the source IP address sent by the fragment receiving module, searches for the route corresponding to the source IP address in the routing table saved by itself, and sends the outgoing interface information of the route to the reorganization interface board selection module; The recombination interface board selection module receives the outgoing interface information sent by the routing search module, determines the interface board identification corresponding to the outgoing interface information, and selects among the interface boards corresponding to the interface board identification according to the pre-configured recombination interface board selection principle One interface board is used as a reorganization interface board, and the recombination interface board identifier is sent to the fragmentation receiving module. 6. The interface board according to claim 5, further comprising: a fragmentation reassembly module, which receives fragments sent by other interface boards and its own fragmentation receiving module, and reassembles all fragments, Moreover, when the fragment receiving module detects that the reorganized interface board identifier sent by the reassembled interface board selection module is its own interface board identifier, it sends the received fragment to the fragment reassembled module. 7. The interface board according to claim 5, further comprising: a reassembly mode configuration module, which stores the correspondence between the fragmentation path information configured by the user and the reassembly mode information supported by the fragmentation, and the fragmentation path information is: the source IP address and/or destination IP address and/or protocol number of the fragment; And, after the fragmentation receiving module receives the fragmentation, it inquires the reorganization mode supported by the fragmentation from the reorganization mode configuration module according to the path information of the fragmentation. Send the fragment to the main control board; if it is found that the distributed reassembly mode is supported, send the source IP address of the fragment to the reassembly interface board determination module.

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