JP3824903B2 - Data relay method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a data relay method and apparatus for determining and relaying a transmission destination of an input data packet.
[0002]
[Prior art]
In the conventional data relay method, in order to determine the relay direction of the input data, for example, when determining based on the destination of layer 2, the bridge function is used to determine the local area network (hereinafter referred to as IEEE 802.3). In the case of “LAN”, it is determined by learning and analyzing the MAC address. Also, when determining based on the layer 3 destination, the router function is used, and if it is IP, the relay direction is determined by analyzing the IP address, and also determining based on the layer 4 destination. In the case of TCP or UDP, the relay direction is determined by analyzing the port number of the service using the router function.
[0003]
In such data relay, there is a software that analyzes and analyzes the destination and type of data for determining the relay direction. In this processing, for example, the CPU once reads program data stored in the DRAM, Since data processing is performed based on information input from hardware, it takes time to read program data from the DRAM and data processing, and data relay processing is not performed quickly.
[0004]
Therefore, in order to increase the speed of the relay processing, there is a method in which the analysis processing by software is replaced with analysis processing using dedicated hardware, a so-called switching mechanism. Examples of devices that perform such switching include what are called layer 3 switches and layer 4 switches in the Internet technology, for example.
[0005]
However, in the above-described conventional example in which the analysis process is performed by hardware, for example, when a fragment in layer 3 occurs, in layer 4 switching, although it is necessary to analyze the header of layer 4, the fragmented 2 Since there is no layer 4 header in the second and subsequent packets, there is a problem that the output destination is not specified and switching cannot be performed.
[0006]
That is, as shown in the packet configuration of each layer in FIG. 4, in the network communication, the communication form is divided for each layer, and each layer has a maximum data length that can be transmitted at one time. For example, in a LAN that is a layer 2 protocol, the maximum value (MTU) of this data length is 1518 bytes in total including a header of 14 bytes, data 1500 bytes, and FCS 4 bytes. ) Is 65535 bytes including an IP header of 20 bytes or more, and in TCP (Transmission Control Protocol) which is a layer 4 protocol, it is about several gigabytes including a TCP header of 20 bytes or more.
[0007]
In a state where the MTU of each layer is determined, the data length of the upper layer is necessarily limited by the data length of the lower layer. In other words, since IP data is encapsulated in a LAN packet, the IP MTU is restricted by the LAN MTU. The TCP MTU is also restricted by the MTU of the LAN for the same reason.
[0008]
For example, even if the IP data length to be transmitted is 4000 bytes, since the MTU of the lower layer Layer 2 LAN is 1500 bytes, the IP data cannot be transmitted at one time. For this reason, the IP data is subjected to fragment processing in layer 3, and is divided into three pieces of data each having a maximum of 1500 bytes. In this division, a header is added to the head of the data part.
[0009]
At this time, TCP data of 3980 bytes, for example, is also divided into three, but here, since it is a fragment at the layer 3 level, the TCP data is simply divided from the top. Therefore, a layer 4 header is present in the first fragmented packet, but a layer 4 header is not present in the second and subsequent packets.
[0010]
Therefore, in Layer 4 switching, although it is necessary to analyze the layer 4 header, the second and subsequent packets that have been fragmented do not have the layer 4 header, so that the analysis becomes difficult. The destination was not specified and switching was impossible.
[0011]
As this first solution, the data from the fragmented head packet to the end packet is temporarily stored in a buffer memory provided in the relay device, and after the packet is reconstructed, it is sent to the specified output destination. It was output.
[0012]
As another second solution, the fragmented second and subsequent packets include an identifier ID indicating the continuation of the first packet, for example, if the layer 3 is IP, the fragment bit and the IP identifier. Since it is stored in the layer 3 header, by recognizing this identifier ID for the input packet, the fragmented second and subsequent packets are relayed in the same direction as the first packet. Was.
[0013]
[Problems to be solved by the invention]
However, in this first solution, the data must be buffered in the relay device from the beginning to the end of the fragmented data until all the data is completed, which hinders the speeding up of the relay processing. It was. Further, this solution has a problem that a large capacity and high price buffer memory such as a DRAM is required to hold a large amount of data.
[0014]
In addition, in the second solution, for example, in the fragmented data, when the second and subsequent packets arrive before the first packet, there is a problem that it is not possible to take a countermeasure. In order to solve this problem, it is necessary to take measures such as buffering the data of the packet in the buffer memory as in the first solution, and the same problem as in the first solution arises.
[0015]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a data relay method and apparatus capable of increasing the speed of relay processing without requiring a large-capacity memory.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a data packet transmitted with a header of each layer is received in a data relay method in which a transmission destination is determined and relayed based on the contents of the header and route information. wherein the hierarchy of the data packet to determine extracts the header of layer 4 analyzes the content of the header output port is the upper layer, and the destination information and the in the header of layer 3 is its lower layer was An analysis step for storing at least the information of the determined output port in the storage means, and if a layer 4 header is added to the received data packet, the data packet is transferred to the determined output port by hardware and also when the header of layer 4 is not added, the contents stored in the storage means from the content of the header of the layer 3 And search, where appropriate content is retrieved, the data retrieval method provided which comprises and a transfer step of transferring the data packet to an output port that is stored in the storage means by hardware Is done.
[0017]
According to the present invention, the analysis function for analyzing the contents of the layer 4 header to determine the output port and storing the address information of the layer 3 header as the address information and the information of the determined output port in the storage means is provided. wherein, when the header of layer 4 in the received data packet is added, and transfers the data packet to an output port determined by the analysis function, if the header of the layer 4 is not added, the layer When the destination information in the header 3 matches the contents of the storage means, the data packet is transferred to the stored output port by hardware, thereby speeding up the relay process using a small-capacity memory. Is possible. [0018]
In a second aspect of the present invention, in the above invention, the the transfer process, the in the data packet without header of the Layer 4, and storage corresponding to the contents of the header of Layer 3 of the data packet in the storage means When there is no content, the data packet is transferred by hardware based on the content of the layer 3 header and the route information.
[0019]
According to the invention, without the header of Layer 4 de Tapaketto, if there is no content corresponding to the content of the layer 3 header in the storage unit, and transfers the data packets by the contents and the path information of the layer 3 header Therefore, it is possible to prevent delay in data transfer and increase the speed of relay processing.
According to a third aspect of the present invention, there is provided route information storage means for storing route information, and a destination is determined from the contents of the header and the route information for a data packet transmitted with a header of each layer. In the data relay apparatus for relaying the data, an analysis means for extracting the header of the layer 4 in which the hierarchy of the received data packet is an upper layer and analyzing the contents of the header, and a lower layer of the data packet Storage means for storing information including at least the destination information in the header of layer 3 and the output port information of the own apparatus as the analysis result, and stored in the storage means from the contents of layer 3 of the data packet. search means for searching the content, when the header of layer 4 data the received packet has been added, the data packet in accordance with the analytical content With transfers by hardware, if said Layer 4 header for data packets is not added, with a transfer means for transferring the data packets by hardware in response to the search results of the searching means A data relay device is provided.
[0023]
According to the present invention, the contents of the layer 4 header are analyzed to determine the output port, the data packet is transferred by hardware, and the destination information in the layer 3 header and the determined output port information are reduced in capacity. If the layer 4 header is not added, the data packet is transferred based on the contents of the retrieved storage means, thereby speeding up the relay process using a small-capacity memory. Plan.
[0024]
According to a fourth aspect of the present invention, in the above invention, the transfer means does not include the layer 4 header in the data packet, and the search means stores the contents of the layer 3 header and the analysis result information in the memory. When retrieved from the means, the data packet is transferred by hardware based on the information of the analysis result.
[0025]
According to the present invention, when there is no layer 4 header and the content of the layer 3 header is retrieved from the storage means, the data packet is delayed by transferring the data packet by hardware based on the corresponding analysis result. To speed up the relay process.
[0026]
According to claim 5 of the present invention, in the above invention, the transfer means does not have the layer 4 header in the data packet, and the search means does not retrieve the contents of the layer 3 header from the storage means. In this case, the data packet is transferred by hardware based on the content of the layer 3 header and the path information stored in the path information storage means.
[0027]
According to the present invention, if there is no layer 4 header and the content of the layer 3 header is not retrieved from the storage means, the data packet is transferred by hardware based on the content of the layer 3 header and the path information. Prevent relay delay and speed up relay processing.
[0028]
According to claim 6 of the present invention, in the above invention, the transfer means includes a switching mechanism for transferring the data packet by hardware.
[0029]
According to the invention, by transferring the data packets by hardware switching mechanism to eliminate the delay of data transfer by software, to speed up the relay process.
[0032]
According to a seventh aspect of the present invention, in the above invention, the storage means comprises a cache memory.
[0033]
According to the present invention, by using a cache memory for registering destination information and output port information, the memory capacity can be reduced and the cost can be reduced.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
Exemplary embodiments of a data relay method and apparatus according to the present invention will be described below with reference to the accompanying drawings.
[0035]
The data relay apparatus according to the present invention is connected between adjacent networks and transfers data packets. Of course, a packet to which a layer 4 header is added is fragmented and a layer 4 header is added. An output destination is searched for each of the packets that have not been processed, and a data packet can be transferred from the output destination to the destination terminal.
[0036]
That is, as shown in FIG. 1, the data relay apparatus includes a packet input unit 11 that captures a packet input from a network such as a WAN or a LAN, and an L3 / L4 header analysis unit that analyzes the contents of the header of the captured packet. 12, an L3 / L4 route table 13 that stores layer 3 and layer 4 route information, a relay result cache unit 14 that stores a relay result analyzed by the L3 / L4 header analysis unit 12, and a plurality of networks. Each packet output unit 15-17 is connected to output a packet.
[0037]
The L3 / L4 header analysis unit 12 constitutes analysis means, search means, and transfer means of the present invention. The L3 / L4 header analysis unit 12 has a switching mechanism for analyzing the contents of the layer 3 header and the layer 4 header added to the input data packet and transferring the packet by hardware based on the analysis result. ing. That is, for the layer 4 header, the L3 / L4 header analysis unit 12 searches the L3 / L4 route table 13 based on the destination address data, etc., obtains route information, finds the shortest route, The switch mechanism is operated so that the output port of the own device to which the relay device is connected is recognized and the data packet is output to the output port. Since this switching mechanism has the same configuration as the existing one shown in the prior art, the description thereof is omitted here.
[0038]
The L3 / L4 header analysis unit 12 extracts the destination address information from the layer 3 header added to the input data packet, and obtains the layer 3 destination address and the above-described analysis. The output port information is written in the relay result cache unit 14. In the writing by the L3 / L4 header analysis unit 12, for the destination address already written in the relay result cache unit 14, the information of the corresponding output port is updated every time a packet is input. .
[0039]
Further, the L3 / L4 header analysis unit 12 uses the layer 3 header in the case where the layer 4 header is not added to the input data packet, for example, in the case of the second and subsequent packets of fragmented data. On the other hand, referring to the L3 / L4 route table 13 based on the destination address data, etc., the route information is obtained to obtain the transmission route, and the output port of the own device to which the next relay device is connected is recognized. Data packets are output to the output port. In this case, since the layer 4 route information cannot be referred to, the shortest route cannot be obtained, but the next relay device that reaches the target destination terminal can be recognized.
[0040]
As described above, the data packet output from the L3 / L4 header analysis unit 12 to a predetermined output port is transmitted to a specific network by the packet output unit connected to the output port.
[0041]
The relay result cache unit 14 constitutes the storage means of the present invention. As shown in FIG. 1, the layer 3 destination address extracted by the L3 / L4 header analysis unit 12 and the output corresponding to this destination address Port information is stored. Note that the destination address shown in this figure is an example of an IP destination address.
[0042]
Next, the relay operation of the data relay apparatus will be described using the flowchart of FIG. In the figure, when a packet is input from the packet input unit 11, the L3 / L4 header analysis unit 12 analyzes the contents of the layer 3 header of this packet (step 101). Then, an identifier ID in this layer 3 header, that is, an identifier indicating a fragmented packet is searched to determine whether or not the input packet is a fragmented packet (step 102).
[0043]
Here, if this packet is a fragmented packet, it is determined whether or not this packet is the first packet of the fragment (step 103). For example, if this packet is the first packet of the fragment, in step 102 If the packet is not a fragmented packet, since the layer 4 header is added to the packet, the layer 4 header is analyzed (step 104).
[0044]
Next, the L3 / L4 route table 13 is searched based on the contents of the layer 3 and layer 4 headers in the packet (step 105), the output destination (the output port of its own device) is determined, and this packet is determined. The destination address of the layer 3 header and the information of the determined output destination are written in the relay result cache unit 14 to update the data (step 107).
[0045]
In step 103, if the input packet is not the first packet of the fragment, the L3 / L4 header analysis unit 12 extracts the layer 3 header of this packet, and the content (destination address) of this layer 3 header. Based on the above, the relay result cache unit 14 is searched (step 108), and it is determined whether or not a cache hit occurs (step 109).
[0046]
Here, if the cache hit does not occur because the destination address to be searched is not stored in the relay result cache unit 14, the L3 / L4 route table 13 based on only the contents of the L3 header of the packet, In this case, the path information of L3 is searched (step 110), the output port is determined, the packet is transferred (step 111), and the next packet and input are waited.
[0047]
If a cache hit is found by searching for the destination address, the output destination is determined from the information of the corresponding output port, the packet is transferred (step 111), and the next packet and input are awaited.
[0048]
Next, the relay operation will be described using an example of the packet arrangement shown in FIG. Here, it is assumed that packets 1, 2, and 3 are fragmented packets with a TCP header added only to packet 1, and packets 1 and 2 are exchanged on a route in the middle of transmission. , B are separate single packets, and a TCP header is added to each.
[0049]
In the case of such TCP data communication, when communication is started, a control system packet for establishing a connection is first transmitted. Since this packet contains only the TCP header and data indicating the start of communication in the encapsulated IP data, no fragmentation occurs. Therefore, in the data relay apparatus, each destination address and output destination information extracted from the TCP header can be written in the relay result cache unit in advance.
[0050]
In this state, when the packet 2 is input, the L3 / L4 header analysis unit 12 analyzes the contents of the IP header of the layer 3 of this packet, recognizes that it is not the head packet of the fragment, and then the IP header It is possible to search the relay result cache unit 14 by using the destination IP address to obtain information of an output port, for example, port 1, and transfer the packet 2 to this port 1.
[0051]
Next, since the layer 4 header is added to the input packets A, 1 and B, the L3 / L4 header analysis unit 12 analyzes the contents of the layer 4 TCP header. Each packet can be transferred to the corresponding port in search of the output port. Here, packet 1 is transferred to port 1, and packets A and B are transferred to port 2, respectively. At the same time, the L3 / L4 header analysis unit 12 searches the storage contents of the relay result cache unit 14 by using the layer 3 destination IP addresses of these packets, and sets the corresponding destination IP address and output port of the relay result cache unit 14. Update information.
[0052]
Next, the packet 3 is input. In this case, the L3 / L4 header analysis unit 12 searches the relay result cache unit 14 by the destination IP address of the IP header of the layer 3 as in the case of the packet 2, Information on the corresponding output port of the relay result cache unit 14 is obtained, and the packet 3 can be transferred to this output port.
[0053]
It should be noted that when data communication is performed after the connection is established, the destination terminal may be connected to another network and changed, and a new terminal may be added. However, in this case as well, when the connection is established, since the control system packet is output from the terminal, the data relay device changes the content of the relay result cache unit 14 based on the content of the header of the input packet. Therefore, data relay processing can be performed without any trouble.
[0054]
As described above, in this embodiment, by combining the packet relay process step with the gate logic by the switching mechanism, the data relay speed can be increased, and the layer 3 destination address of the packet and the output port corresponding thereto This information is stored in the cache memory so that the output port can be determined from the contents of the layer 3 header even for, for example, a fragmented packet to which no layer 4 header is added. For this reason, in this embodiment, the capacity of data stored in the memory is significantly reduced compared to the conventional example, and even for a packet without a layer 4 header without requiring a large capacity memory. It became possible to speed up the relay processing.
[0055]
The present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the present invention.
[0056]
【The invention's effect】
As described above, the present invention includes a hardware analysis function that determines the output port by analyzing the contents of the upper layer header. When the upper layer header is added to the received data packet, When the data packet is transferred to the output port determined by the analysis function and this upper layer header is not added, the storage means is searched by the content of the lower layer header, and the stored content matches the content of this header. Sometimes, the forwarding process can be speeded up by transferring the data packet to the stored output port.
[0057]
Further, in the present invention, when there is no upper layer header in the data packet and there is no content corresponding to the content of the lower layer header in the storage means, the output port is determined by the content of the lower layer header and the route information, and the data Since the packet is transferred, it is possible to prevent delay in data transfer and increase the speed of the relay process.
[0058]
Furthermore, in the present invention, the contents stored in the storage means are information on the lower layer destination address and information on the corresponding output port. For packets to which no upper layer header is added, this lower layer Since the storage means is searched from the destination address of the layer and the output port is determined, the relay process can be speeded up using this memory, and the memory capacity can be reduced.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a functional configuration of a data relay device according to the present invention;
FIG. 2 is a flowchart showing a relay operation of the data relay device shown in FIG. 1;
FIG. 3 is a diagram illustrating an example of a packet arrangement and an L3 / L4 header analysis unit for explaining a relay operation.
FIG. 4 is a configuration diagram showing a packet configuration of each layer for explaining a fragment in layer 3;
[Explanation of symbols]
11 Packet input unit 12 L3 / L4 header analysis unit 13 L3 / L4 route table 14 Relay result cache unit 15-17 Packet output unit

Claims (7)

In a data relay method for relaying a data packet transmitted with a header of each layer by determining a transmission destination based on the content of the header and route information,
The layer 4 header , which is the upper layer of the received data packet , is extracted, the contents of the header are analyzed to determine the output port, and the destination information in the layer 3 header , which is the lower layer, and An analysis step of storing information of the determined output port in at least storage means;
When a layer 4 header is added to the received data packet, the data packet is transferred to the determined output port by hardware, and when a layer 4 header is not added, the layer 3. The content stored in the storage means is searched from the content of the header of No. 3, and when the corresponding content is searched, the data packet is transferred by hardware to the output port stored in the storage means Process ,
A data relay method comprising: Wherein the transfer step, the inside data packet said layer without header of 4, and wherein if there is no stored content that corresponds to the header of the contents of the Layer 3 data packets in the storage means, the header of the Layer 3 2. The data relay apparatus according to claim 1, wherein the data packet is transferred by hardware based on contents and the path information. Data that has route information storage means for storing route information, and relays the data by determining a transmission destination from the contents of the header and the route information for a data packet transmitted with a header of each layer In the relay device,
Analyzing means for extracting a layer 4 header whose upper layer is the received data packet and analyzing the content of the header;
Storage means for storing information including at least destination information in a header of a layer 3 that is a lower layer of the data packet and information on an output port of the own apparatus that is the analysis result;
Search means for searching the contents stored in the storage means from the contents of layer 3 of the data packet;
When a layer 4 header is added to the received data packet, the data packet is transferred by hardware according to the analysis content, and when the layer 4 header is not added to the data packet Transfer means for transferring the data packet by hardware according to the search result of the search means ;
A data relay device comprising: When the data packet does not have the layer 4 header and the search unit retrieves the content of the layer 3 header and the analysis result information from the storage unit, the transfer unit performs the analysis result. 4. The data relay apparatus according to claim 3 , wherein the data packet is transferred by hardware based on the information. Said transfer unit, when the data packet the no header of Layer 4, and the contents of the header of the Layer 3 is not retrieved from the storage means by said retrieval means, the contents of the header of the Layer 3 based on the route information stored in the route information storage means, the data relay device according to claim 3 or 4, wherein the transfer of the data packets by hardware. It said transfer means, the data relaying apparatus according to any one of claims 3-5, characterized in that it comprises a switching mechanism for transferring the data packets by hardware. The data relay apparatus according to any one of claims 3 to 6 , wherein the storage unit includes a cache memory.

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