JP4646650B2 - Network connection device - Google Patents

Description

  The present invention relates to a network connection device used for a network such as Ethernet (registered trademark) used in, for example, plant monitoring and control.

  In a network connection device, when a packet having a data length exceeding the MTU (Maximum Transmission Unit) is transferred, a packet is transferred between a TCP (Transmission Control Protocol) / IP (Internet Protocol) layer and a MAC (Media Access Control) layer. As a countermeasure against this problem, for example, a network connection device described in Japanese Patent Application Laid-Open No. 11-317762 (Patent Document 1) is considered.

  That is, in the network connection device described in Patent Document 1, on the transmission side, the data received from the TCP / IP layer is divided by the frame dividing unit according to the size of the MTU, and the IP header and the TCP are divided into the divided pieces. Add a header. On the receiving side, the received frame is combined at the frame combining unit and restored to the first data, thereby preventing a decrease in communication performance due to an increase in communication load when a packet having a data length exceeding the MTU is transferred. is there.

JP 11-317762 A (FIGS. 1 and 2, paragraphs 0007 to 0010)

  In the conventional technique as described in Patent Document 1, a frame division unit is placed while data is transferred from the TCP / IP layer to the physical layer, and the TCP / IP packet is divided by the frame division unit, and each of the divided pieces is divided. Since the IP header and the TCP header are added, if the number of divisions increases, the TCP / IP headers increase and waste occurs, and the frame division unit passes data from the TCP / IP layer to the physical layer. Since the packet segmentation / IP / TCP header addition process is inserted, there is a problem that the process takes time.

  The present invention has been made in view of the above-described circumstances. In the data transfer of the network connection device, when transferring a packet having a data length exceeding the MTU of the network to be used, an increase in communication load is suppressed. The purpose is to prevent a decrease in communication efficiency.

The network connection device according to the present invention includes a TCP / IP processing unit and a MAC processing unit, and transmits and receives data to and from the network. An address designated by the TCP / IP processing unit is assigned by the MAC processing unit. A network connection device that includes an address conversion unit that converts an address that does not overlap an area in which a MAC header is set, sets transmission data in the area of the address converted by the address conversion unit, and transmits the transmission data to the network together with the MAC header In addition, as control information for assembling the divided packets, a frame number to be added to each packet before being divided from the TCP / IP layer in the MAC layer and a sequence number to be sequentially given to the divided frames MAC frame options It is intended to be set in ® down area.

According to the present invention, in a network connection device having a TCP / IP processing unit and a MAC processing unit for transmitting / receiving data to / from a network, an MAC header is set by the MAC processing unit with an address designated by the TCP / IP processing unit. An address conversion unit that converts an address that does not overlap an area to be transmitted, sets transmission data in the area of the address converted by the address conversion unit, and transmits the data together with the MAC header to the network. As frame control options for assembling the divided packets, a frame number added to each packet before being divided and received from the TCP / IP layer in the MAC layer, and a sequence number that is sequentially given to the divided frames are options of the MAC frame. since the set in the area, The data area handled by the TCP / IP layer and MAC layer during communication can be handled as a continuous data area from the TCP / IP layer, and a MAC header is added for each MTU size from the MAC layer and hardware. Since the TCP / IP layer does not need to divide and assemble packets, when a packet with a data length exceeding the MTU size is transmitted / received, an increase in the communication load in the TCP / IP layer is caused. A decrease in communication efficiency can be prevented.

Embodiment 1 FIG.
A first embodiment of the present invention will be described below with reference to FIG. 1 showing an example of a network connection device.

  In FIG. 1, the network connection device 100 includes a data transmission / reception processing unit 1 and a data transmission / reception unit 4, and is connected to an Ethernet (registered trademark) 200. The Ethernet (registered trademark) 200 is a network such as a LAN used for plant monitoring and control, for example.

  The data transmission / reception processing unit 1 includes a TCP / IP processing unit 2 and a MAC processing unit 3.

  The data transmission / reception unit 4 includes an address conversion unit 5, a transmission buffer 6, an Ethernet (registered trademark) frame transmission unit 7, a reception buffer 8, an Ethernet (registered trademark) frame reception unit 9, an address signal line 10, and a data signal line 11. have.

  Next, the operation will be described.

  The TCP / IP processing unit 2 sets transmission data in the transmission buffer 6. In this case, the address designated by the TCP / IP processing unit 2 is converted by the address conversion unit 5 and sent to the transmission buffer 6 through the address signal line 10.

  Specifically, the address conversion by the address conversion unit 5 is performed by the conversion address conversion unit 5 in the area where the MAC header is set, as shown in FIG. 3, the address specified by the TCP / IP processing unit 2. Convert to a non-overlapping address. 3 will be described later in the second embodiment.

  Simultaneously with this address conversion, transmission data is also sent to the transmission buffer 6, and the transmission data is set in the designated address area of the transmission buffer 6.

  When the transmission data is set in the transmission buffer 6, the MAC processing unit 3 is activated, and after the MAC processing unit 3 sets a MAC header for each MTU (eg, 1500 bytes) in the transmission buffer 6, Ethernet (registered trademark) A transmission command is issued to the frame transmission unit 7.

  The Ethernet (registered trademark) frame transmission unit 7 that has received the transmission instruction reads the MAC header and transmission data from the transmission buffer 6 by a size (for example, 1500 bytes) set in the MTU, that is, in units of MTU (in other words, the MAC header The data is divided and transmitted to the Ethernet (registered trademark) 200. The Ethernet (registered trademark) frame transmission unit 7 performs this operation up to the final data of the transmission data set by the TCP / IP processing unit 2.

  At the time of reception, the Ethernet (registered trademark) frame receiving unit 9 receives the data, and the Ethernet (registered trademark) frame receiving unit 9 writes the received frame in the intermediate storage area in the reception buffer 8 and notifies the MAC processing unit 3 of the received frame.

  Receiving this notification, the MAC processing unit 3 stores the reception frames divided for each of the plurality of MAC headers in the data storage area in the reception buffer 8 in the order of the data, that is, in the order of the MAC addresses. After receiving the final data, the TCP / IP processing unit 2 is notified.

  Upon receiving this notification, the TCP / IP processing unit 2 reads the data stored in the data storage area in the reception buffer 8 in the order of the MAC addresses as described above. At that time, the address conversion unit 5 reads the MAC header (see FIG. 3), the data can be handled as continuous data in the order of the data addresses, and the assembly of packets at the TCP / IP layer is not necessary.

  As described above, in the network connection device 100 according to the first embodiment of the present invention, the data area handled by the TCP / IP layer and the MAC layer at the time of transmission is handled as a continuous data area from the TCP / IP layer. Since the MAC layer and the hardware have the address conversion unit 5 configured so that it can be handled as an area to which a MAC header is added for each MTU size, the data length exceeding the MTU of the network to be used can be obtained. When transmitting / receiving a packet, the TCP / IP layer does not need to divide and assemble the packet in accordance with the MTU.

  In this way, by providing the address translation mechanism 5, the TCP / IP layer is configured so that packet division / assembly is not required. Therefore, as in the above-mentioned Patent Document 1, a frame division unit is provided, Packet division in the TCP / IP layer in the case of transferring a packet having a data length exceeding the MTU as compared with a case where the frame division unit divides a TCP / IP packet and adds an IP header and a TCP header to each divided portion. -The communication performance can be improved by reducing the assembly processing load.

Embodiment 2. FIG.
The second embodiment of the present invention will be described below with reference to FIG. 2 showing an example of the operation of the address translation unit and FIG. 3 showing an example of the address after the TCP / IP buffer address is translated by the address translation unit.

  FIG. 2 illustrates an address map 12 viewed from the TCP / IP layer and the MAC layer, the contents 13 of the TCP / IP buffer, and the buffer entity 14. The TCP / IP buffer and the MAC buffer are defined in different spaces on the address map 12, and can be handled as different areas. In the TCP / IP buffer 13, an IP header, a TCP header, and data set by the TCP / IP layer are written. These IP header, TCP header, and data are set for each TCP / IP packet.

  The TCP / IP buffer address is converted by the address conversion unit 5 (see FIG. 1) into an address indicated by the buffer entity 14. In the buffer entity 14, that is, the MAC / Ethernet (registered trademark) frame transmission / reception unit buffer, the content is a content obtained by adding a MAC header to the content 13 viewed from the TCP / IP buffer, whereas the buffer / TCP buffer uses the TCP / IP buffer. The address is converted so that the MAC header portion cannot be seen. By the operation of the address conversion unit 5, data can be set from the TCP / IP layer without being aware of packet division / assembly.

FIG. 3 shows an example of the address after the TCP / IP buffer address is converted by the address conversion unit 5. The TCP / IP buffer address is converted by the address conversion unit 5 as follows.
C + ((TCP / IP buffer address−A) ÷ 1500 quotient) × 18 + 18
Here, 1500 is an Ethernet (registered trademark) MTU size of 1500 bytes, and 18 is a MAC header length of 18 bytes. By performing this conversion, the transmission data can be set from the TCP / IP layer to the TCP / IP buffer address without dividing the transmission data, and the MAC layer can be used for the MAC. Since the MAC header can be inserted through the buffer address, packet division at the TCP / IP layer becomes unnecessary when transmitting a packet having a data length exceeding the MTU. Since this is also performed for the reception buffer, packet assembly at the TCP / IP layer is not necessary.

  As shown in FIG. 2 and FIG. 3, the data areas handled by the TCP / IP layer and the MAC layer are configured to be physically the same, so that complicated processing at the time of data transfer between the two is performed. It becomes unnecessary.

Embodiment 3 FIG.
The third embodiment of the present invention will be described below with reference to FIG. 4 showing an example of the structure of frame numbers and sequence numbers.

  As shown in FIG. 4, the MAC header 15 defined in IEEE 802.1Q has identification codes called VLAN tags, as is well known, TPID (Tag Protocol IDentifier) and TCI (Tag Control Information). A frame number (4 bits) and a sequence number (8 bits) are set in the TCI section 16 which is this optional area. The frame number is incremented for each packet from the TCP / IP layer, and its range is from 0 to 15. The sequence number is set in order for each frame when the data is divided and transmitted in the MAC layer as described above, and the range is from 0 to 255. By using these, on the receiving side, it is possible to assemble data divided and transmitted in the MAC layer.

  In this way, since the frame number added for each packet and the sequence number that is sequentially given to the divided frames are set in the option area of the MAC frame at the time of transmission, by using these, on the receiving side, The data divided and transmitted by the MAC layer can be assembled.

Embodiment 4 FIG.
Hereinafter, Embodiment 4 of the present invention will be described based on FIG. 5 showing an example of a processing flow in the MAC layer at the time of data reception.

  As shown in FIG. 5, at the time of frame reception, the MAC layer refers to the source MAC address and the frame number (ID) of the option area (step ST1) and checks whether the data is divided (step ST2). ).

  If the check result in step ST2 is the divided data, the sequence number is referred to and stored in the buffer in order (step ST3).

  Next, it is determined whether or not all frames have been received (step ST4), and if reception of all frames is completed as a result of determination in step ST4, a reception notification is sent to the TCP / IP layer (step ST5). By this processing, it is possible to assemble data divided and transmitted by the MAC layer.

  If the check result in step ST2 is not divided data, it is not necessary to refer to the sequence number, and the process proceeds to step ST5.

  If the result of determination in step ST4 is that reception of all frames has not been completed, reception of the next frame is awaited (step ST6).

  As described above, since the reception process is configured with reference to the source MAC address, the frame number and the sequence number set in the option area of the MAC frame, it is divided at the MAC layer at the time of reception by this process. The transmitted data can be assembled.

Embodiment 5. FIG.
The fifth embodiment of the present invention will be described below with reference to FIG. 6 showing another example of the network connection device.

  FIG. 6 shows a configuration in which the MTU size can be changed from the outside from the TCP / IP layer or the like, and an MTU size setting unit 17 is provided. The address conversion unit 5 performs address conversion using the MTU value set in the MTU size setting unit 17. As a result, the MTU size can be changed in accordance with the network to be used, and it can be applied not only to Ethernet (registered trademark) but also to other networks.

It is a figure which shows Embodiment 1 of this invention, and is a figure which shows the example of a network connection apparatus. It is a figure which shows Embodiment 2 of this invention, and is a figure showing the example of operation | movement of an address conversion part. It is a figure which shows Embodiment 2 of this invention, and is a figure which shows the example of the address after the conversion of the buffer address for TCP / IP by the address conversion part. It is a figure which shows Embodiment 3 of this invention, and is a figure which shows the example of a structure of a frame number and a sequence number. It is a figure which shows Embodiment 4 of this invention, and is a figure showing the example of the processing flow in the MAC layer at the time of data reception. It is a figure which shows Embodiment 5 of this invention, and is a figure which shows the example of a network connection apparatus.

Explanation of symbols

1 Data transmission / reception processor
2 TCP / IP processing unit,
3 MAC processing part,
4 Data transmitter / receiver,
5 Address converter,
6 Send buffer,
7 Ethernet (registered trademark) frame transmitter,
8 Receive buffer,
9 Ethernet (registered trademark) frame receiver,
10 Address signal line,
11 Data signal line,
12 Address map,
13 Contents of TCP / IP buffer,
14 Buffer entity,
15 MAC header,
16 TCI content,
17 MTU size setting section,
100 network connection device 100,
200 Ethernet (registered trademark) (network).

Claims (3)

In a network connection device having a TCP / IP processing unit and a MAC processing unit for transmitting and receiving data to and from a network,
An address conversion unit that converts an address designated by the TCP / IP processing unit into an address that does not overlap an area in which a MAC header is set by the MAC processing unit is provided, and the address converted by the address conversion unit A network connection device that sets transmission data and transmits the data together with the MAC header to the network,
As control information for assembling the divided packets, a frame number added to each packet before being divided and received from the TCP / IP layer in the MAC layer, and a sequence number given sequentially to the divided frames are A network connection device set in an option area . In a network connection device having a TCP / IP processing unit and a MAC processing unit for transmitting and receiving data to and from a network
An address conversion unit that converts an address designated by the TCP / IP processing unit into an address that does not overlap an area in which a MAC header is set by the MAC processing unit is provided, and the address converted by the address conversion unit The transmission data is set and transmitted to the network together with the MAC header, and the address conversion unit is a network connection device that performs address conversion excluding the MAC header from the received data from the network,
As control information for assembling the divided packets, a frame number added to each packet before being divided and received from the TCP / IP layer in the MAC layer, and a sequence number given sequentially to the divided frames are A network connection device set in an option area . The network connection device according to claim 1 or 2 ,
When the divided frame is received, it is checked whether it is divided data by referring to the source MAC address and the frame number of the option area. If it is divided data, the data is stored in order by referring to the sequence number. A network connection device characterized by that.

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