JP4881836B2 - Communication control method and communication control apparatus - Google Patents

Description

  The present invention relates to communication control, and more particularly to communication control for communication performed by an upstream node and a downstream node by transmitting and receiving data packets and response packets using wired or wireless lines having different transmission speeds for upstream and downstream.

  For example, when transferring a file as data transfer between two nodes (end nodes), such as connecting to the Internet via a line such as the ADSL method and downloading a file from a server on the Internet, FTP (File Transfer Protocol) is used as a communication method. Is generally used. Thus, FTP is widely used because of the characteristics of FTP. In other words, in FTP, it is possible to perform communication with the maximum throughput between nodes without knowing the transmission speed between the two nodes, and a network composed of a plurality of routes such as the Internet. It is suitable for communication with a large number of unspecified sites.

  In such FTP communication, there is the following relationship between the maximum throughput between two nodes and the round-trip time (RTT) (for example, Non-Patent Document 1).

Maximum throughput between two nodes x RTT = C
Here, C is referred to as a window size, which is the amount of data that a node can send out at once, and is a value determined by the CPU of the node, the capacity of the memory, and the like.

  In FTP, after a data packet generated by dividing a file to be transferred is transmitted, a response packet such as an ACK packet sent from the file receiving node is sent to the file transmitting node in order to respond to the reception of the transmitted data packet. RTT is acquired from the time until reception, and communication is performed using the RTT so that the throughput between the two nodes is maximized by the above relationship. In other words, in FTP, the RTT value obtained during file transfer is used to adjust the data transmission rate, so that file transfer can be performed at maximum throughput without knowing the transmission rate of the line between the two nodes. It is.

TCP / IP W.Richard Stevens, translated by Naoji Inoue, SoftBank Corp. (ISBN4-7973-0232-1)

  In FTP communication, the transmission paths (upstream transmission path and downstream transmission path) of two nodes that transmit and receive files (hereinafter, one is an upstream node and the other is a downstream node) are the same transmission rate. If there is, communication at the maximum throughput can be performed as described above. In addition, even in the case of an asymmetric method such as an ADSL method in which the transmission speed is different between an upstream node and a downstream node, file transfer in FTP communication is performed only on the upstream node or only on the downstream node. Anyway, communication at the maximum throughput can be performed as described above.

  However, in the asymmetric method, a problem occurs when the file transfer in the FTP method is performed simultaneously in the upstream node and the downstream node.

  FIG. 8 shows an example of a general configuration of a conventional communication system in the case of performing FTP communication using an asymmetrical line. The communication system Cs in FIG. 8 includes an advancing node 3 and a downlink node 2 each having an FTP processing unit 1 for communication based on the FTP method, and an asymmetric scheme configured by a downlink transmission path 4 and an uplink transmission path 5. Network (which can be wired or wireless). Note that the transmission speed of the downstream transmission path 4 is temporarily 2 Mbps, and the transmission speed of the upstream transmission path 5 is temporarily 1 Mbps.

  The downstream node 2 is, for example, a server device, has an Ethernet (registered trademark) interface (not shown) that is a general-purpose network interface, and is connected to the network via the Ethernet 6 that is one of LANs (local area networks). It is connected to the device 7 and further connected to the downstream transmission line 4 and the upstream transmission line 5 via the network connection device 7. On the other hand, the upstream node 3 is, for example, a client terminal, and has an Ethernet interface (not shown) that is also a general-purpose network interface, and is connected to the network connection device 9 via the Ethernet 8. Via the downstream transmission line 4 and the upstream transmission line 5. The downstream node 2 and the upstream node 3 establish a TCP connection with each other by the respective FTP processing units 1 and perform communication according to the FTP procedure.

  The network connection device 7 and the network connection device 9 have a function of buffering a speed difference between the transmission rate of, for example, 100 Mbps in the Ethernet 6 or the Ethernet 8 and the transmission rate of the downstream transmission line 4 or the upstream transmission line 5, and for this purpose, the buffer 11 And a buffer 12 are provided.

  The network connection device 7 sends packets (downlink data packet 13 and downlink response packet 14) received from the downlink node 2 via the Ethernet 6 to the downlink transmission path 4 and receives packets (uplink data packet) from the uplink transmission path 5. 15 and the upstream response packet 16) are sent to the Ethernet 6.

  On the other hand, the network connection device 9 sends packets (uplink data packet 15 and uplink response packet 16) received from the upstream node 3 via the Ethernet 8 to the uplink transmission path 5 and receives packets (downlink) from the downlink transmission path 4. The data packet 13 and the downlink response packet 14) are sent to the Ethernet 8.

  The network connection device 7 and the network connection device 9 temporarily store the packet in the buffer 11 or the buffer 12 as the buffer function when the packet is transmitted to the downlink transmission path 4 or the uplink transmission path 5. The storage time of the packets in the buffer 11 and the buffer 12 is determined by the congestion state of the downlink transmission path 4 and the uplink transmission path 5.

  In such a communication system, the downstream node 2 and the upstream node 3 communicate by transmitting / receiving a downstream data packet 13, an upstream data packet 15, a downstream response packet 14, and an upstream response packet 16. Here, the downlink response packet 14 is a packet transmitted from the downlink node 2 to the uplink node 3 in order to respond to reception of the uplink data packet 15, and the uplink response packet 16 is response to reception of the downlink data packet 13. Is a packet transmitted from the upstream node 3 to the downstream node 2. On the other hand, the downstream data packet 13 is a packet used by the downstream node 2 to transmit a file or the like to the upstream node 3, and the upstream data packet 15 is transmitted from the upstream node 3 to the downstream node 2. This packet is used for However, in this specification, the data packet also has a meaning as representing a packet other than the response packet.

A state in which the downstream node 2 and the upstream node 3 execute such communication simultaneously in parallel, that is, the upstream node 3 sends out the upstream data packet 15 at the same time as the downstream node 2 sends out the downstream data packet 13. When the FTP communication is executed, the network connection device 9 starts to increase the number of uplink response packets 16, and reaches a state where it occurs up to twice as many as the uplink data packets 15. This is because the downlink transmission rate is twice the uplink transmission rate as described above.

  In such a state, a part of the uplink response packet 16 cannot be sent to the uplink transmission path 5 for transmission of the uplink data packet 15 but is stored in the buffer 12 of the network connection device 9. Wait until there is a free space. As a result, the RTT of the downlink data packet 13 increases. That is, the frequency of sending the uplink response packet 16 to the uplink transmission path 5 is reduced as compared with immediately after the start of communication, and the uplink response packet 16 is transmitted through the uplink transmission path 5 alternately with the uplink data packet 15. For this reason, the RTT of the downstream data packet 13 increases to the same value as the RTT of the upstream data packet 15, and is in an equilibrium state there. In this case, since the downlink side node 2 performs the data transmission rate adjustment as described above, the throughput of the downlink transmission path 4 starts to decrease to 2 Mbps or less, and finally decreases to 1 Mbps, and reaches an equilibrium state there. .

  On the other hand, when attention is paid to the upstream data packet 15, no increase in RTT occurs. This is because, as the maximum throughput of the downlink transmission line 4 starts to decrease to 2 Mbps or less, an empty band is generated in the downlink transmission line 4, and the downlink response packet 14 is stored in the buffer 12 of the network connection device 7. This is because the downlink response packet 14 does not have to wait for the downlink transmission path 4 to be idle, and is immediately sent to the downlink transmission path 4.

  As described above, in the asymmetric method, when data transfer in FTP communication is performed simultaneously between the upstream node and the downstream node, the throughput of the downstream transmission path is actually increased even though the bandwidth of the downstream transmission path is free. This causes a problem that the throughput may eventually decrease to the same throughput as that of the slow transmission line. That is, there is a problem that the communication efficiency may be lowered due to the inability to utilize the high transmission speed of the downlink transmission path in the asymmetric system.

  The present invention has been made on the basis of the above knowledge, and its problem is to increase the maximum throughput of the high-speed transmission line for communication performed by transmission / reception of data packets and response packets in a communication line of an asymmetric system. It is an object of the present invention to provide a communication control method and a communication control device used therefor that enable more efficient communication by always ensuring the upper limit of the transmission band of the high-speed transmission path.

  As described above, the decrease in communication efficiency in the asymmetric scheme is that when the downstream node and the upstream node are performing data transmission simultaneously as file transfer or the like, the upstream response packet is waiting for transmission by the upstream data packet. This occurs due to an increase in RTT of the downlink data packet.

  In order to effectively solve the problem of lowering the communication efficiency, it is only necessary to prevent the upstream response packet from waiting for transmission by the upstream data packet. That is, by doing so, RTT can be made only for the pure round-trip transmission time in each of the uplink transmission line and the downlink transmission line for both uplink and downlink, and the maximum throughput of each of the uplink transmission line and the downlink transmission line. Can always be secured up to the upper limit of each transmission band, and the problem of lowering communication efficiency can be effectively solved.

  In order to prevent the upstream response packet from waiting for transmission by the upstream data packet, the upstream response packet may be controlled to be transmitted with priority over the upstream data packet.

  In the present invention, the above-mentioned problems are solved based on the above concept. Specifically, an upstream node and a downstream node connected to communication lines having different transmission speeds of the upstream transmission path and the downstream transmission path respond to the data packet for data transmission and the reception of the data packet. In the communication control method for communication performed by packet transmission / reception, the uplink response packet for the uplink response packet that is the response packet transmitted by the uplink node and the uplink data packet that is the data packet transmitted by the uplink node is It is characterized by preferentially transmitting the uplink data packet.

  In the present invention, for the communication control method as described above, the transmission rate ratio control method for controlling the transmission rate of the uplink response packet and the uplink data packet to be the same as the ratio of the uplink and downlink transmission rates. A response packet dedicated buffer for storing only the upstream response packet and a data packet buffer for storing the upstream data packet are provided for the upstream node, and there is a vacancy in the upstream transmission path. In a selection control method for controlling transmission of the uplink data packet stored in the data packet buffer on condition that all the uplink response packets stored in the response packet dedicated buffer are transmitted. Only for response packets that perform the preferential transmission or store only the uplink response packet A buffer for data packet storing the buffer and the upstream data packet is provided for the upstream node, a data length threshold is set for continuous transmission of the upstream data packet, and an empty transmission path is created In packet transmission, every time the transmission data length in the continuous transmission of data packets stored in the data packet buffer exceeds the data length threshold, all the upstream response packets stored in the response packet dedicated buffer are transmitted. The preferential transmission is performed by the data length reference control method to be controlled as described above.

In the present invention, the communication control apparatus connected to the upstream node for use in the communication control method as described above is configured to include a packet transmission control unit for control by the transmission rate ratio control method. Or a packet that includes the response packet dedicated buffer and the data packet buffer, and controls packet storage in each of the response packet dedicated buffer and the data packet buffer by determining a packet generated by the upstream node. A storage control unit and a packet transmission control unit for control by the selection control method, or the response packet dedicated buffer, the data packet buffer, and the data length threshold are held A threshold value holding unit is provided and is generated at the upstream node. A packet storage control unit that controls packet storage in each of the response packet dedicated buffer and the data packet buffer, and further includes a packet transmission control unit for control by the data length reference control method. It is assumed that it is configured to include.

  According to the present invention as described above, the maximum throughput of the high-speed transmission line is always ensured up to the upper limit of the transmission band of the high-speed transmission line for communication performed by transmitting and receiving data packets and response packets on the communication line of the asymmetric system. It becomes possible to perform more efficient communication.

  Hereinafter, modes for carrying out the present invention will be described. FIG. 1 shows a configuration of a communication system to which the communication control method according to the first embodiment is applied. The communication system 20 in FIG. 1 is the same as the conventional communication system Cs described above in its basic configuration. Therefore, elements common to the communication system Cs are denoted by the same reference numerals as in FIG. 8, and description thereof will be omitted as appropriate.

  In the communication system 20, the network connection device 21 connected to the upstream node 3 has a response packet priority control function. That is, the network connection device 21 includes a response packet dedicated buffer 22, a data packet buffer 23, a packet storage control unit 24, and a packet transmission control unit 25 of a transmission rate ratio control method. Is preferentially transmitted to the uplink data packet 15, and also serves as a communication control device for the response packet priority control function.

  The response packet dedicated buffer 22 is used to store the upstream response packet 16 exclusively. On the other hand, the data packet buffer 23 is used to store packets other than the upstream response packet 16 (this is represented by the upstream data packet 15 as described above).

The packet storage control unit 24 controls packet storage in the response packet dedicated buffer 22 and the data packet buffer 23. Specifically, it is determined whether the packet generated by the upstream node 3 and transmitted via the Ethernet 8 is the upstream data packet 15 or the upstream response packet 16. And if it is determined that the uplink response packet 16 stores it in the response packet dedicated buffer 22, if it is determined not to be the uplink response packet 16 stores the packet in the data packet buffer 23.

  The packet transmission control unit 25 of the transmission rate ratio control method transmits the transmission rate so that the transmission rate of the uplink response packet 16 and the uplink data packet 15 is the same as the ratio of the transmission rates of the upstream transmission path 5 and the downstream transmission path 4. The transmission of the packet to the upstream transmission path 5 is controlled by the ratio control method. The transmission rate in this case is the ratio of the number of transmissions in the continuous transmission of the uplink response packet 16 and the number of transmissions in the continuous transmission of the uplink data packet 15, and the transmission data length and the uplink data packet in the continuous transmission of the uplink response packet 16. It is possible to have a ratio of the transmission data length in 15 continuous transmissions. In this embodiment, the ratio is the number of transmissions. In the case of the ratio of the number of transmissions, for example, if the upstream transmission path 5 is 1 Mbps and the downstream transmission path 4 is 2 Mbps, when two upstream response packets 16 are sent to the upstream transmission path 5, the upstream data packet 15 is transmitted upstream. The transmission of packets is controlled so that the transmission ratio of the upstream response packet 16 and the upstream data packet 15 to the upstream transmission path 5 is 2: 1.

Below, the communication control process in the communication system 20 is demonstrated. In the downstream node 2 and the upstream node 3, the respective FTP processing units 1 perform file transfer according to a normal FTP procedure. When attention is paid to the upstream node 3 in a state where such file transfer is performed simultaneously in parallel between the downstream node 2 and the upstream node 3, packets generated by the upstream node 3 (upstream data packets 15 and upstream The response packet 16) is sent to the Ethernet 8 by the FTP processing unit 1, and reaches the network connection device 9 via the Ethernet 8.

The packet that has reached the network connection device 9 is processed by the packet storage control unit 24 and temporarily stored in the response packet dedicated buffer 22 or the data packet buffer 23. Specifically, the packet storage control unit 24 first determines whether the packet that has reached the network connection device 9 is the upstream response packet 16 or the upstream data packet 15. Then, if the packet storage control unit 24 determines that it is an upstream response packet 16, it stores this in the tail of the response packet dedicated buffer 22, while if it determines that it is an upstream data packet 15, it stores this at the end of the data packet buffer 23. To store.

  The upstream response packet 16 and the upstream data packet 15 stored in the response packet dedicated buffer 22 and the data packet buffer 23 are sent to the upstream transmission path 5 by the packet transmission control unit 25. At this time, the packet transmission control unit 25 gives priority to the uplink response packet 16 over the uplink data packet 15 and sends it to the uplink transmission line 5 as described above. That is, the uplink response packet 16 is prioritized over the uplink data packet 15 by the packet transmission control in the above transmission rate ratio control method. Such packet transmission control makes it possible to always ensure the maximum throughput of the high-speed downlink transmission path 4 up to the upper limit of the transmission band of the downlink transmission path 4. This allows more efficient communication.

  Hereinafter, details of the processes in the packet storage control unit 24 and the packet transmission control unit 25 will be described. FIG. 2 shows a flow of processing of packet storage control performed by the packet storage control unit 24. The packet storage controller 24 first determines whether a packet has been received from the Ethernet 8 (step S11). This reception determination is repeated until there is packet reception. If there is packet reception in step S11, the process proceeds to step S12. In step S12, the received packet is determined. This packet determination is performed as “Is the received packet the uplink response packet 16?”. Specifically, for example, the ACK bit of the TCP header in the packet is checked. If the ACK bit is ON and the TCP data part does not exist, the packet is determined to be the uplink response packet 16. If the determination result in step S12 is affirmative, the process proceeds to step S13, and the received packet, that is, the uplink response packet 16 is stored at the tail end of the response packet dedicated buffer 22. On the other hand, if the determination result of step S12 is negative, the process proceeds to step S14, and the received packet, that is, the upstream data packet 15, is stored at the end of the data packet buffer 23.

  FIG. 3 shows the flow of packet transmission control processing performed by the packet transmission control unit 25. The packet transmission control unit 25 first determines whether there is a packet waiting for transmission, that is, whether there is an upstream response packet 16 stored in the response packet dedicated buffer 22 or an upstream data packet 15 stored in the data packet buffer 23 ( Step S21). This transmission waiting packet determination is repeated until there is a transmission waiting packet. If there is a transmission waiting packet in step S21, the process proceeds to step S22. In step S22, it is determined whether there is a vacancy in the upstream transmission path 5. This transmission path availability determination is repeated until there is an availability. If space is available in step S22, the process proceeds to step S23. In step S23, it is determined whether there is an upstream response packet 16 waiting for transmission. If the determination result of step S23 is negative, the process proceeds to step S25. On the other hand, if the determination result in step S23 is affirmative, the uplink response packet 16 is continuously transmitted by the first number (step S24). Next, it is determined whether there is an upstream data packet 15 waiting for transmission (step S25). If the determination result of step S25 is negative, the process returns to step S21. On the other hand, when the determination result of step S25 is affirmative, the process proceeds to step S26, and the second number of uplink data packets 15 are continuously transmitted, and then the process returns to step S21. Here, the first number and the second number are set so that these ratios are the same as the ratios of the transmission rates of the upstream transmission path 5 and the downstream transmission path 4.

  FIG. 4 shows a configuration of a communication system to which the communication control method according to the second embodiment is applied. The communication system 30 in FIG. 4 is the same as the communication system 20 in the first embodiment in its basic configuration. Therefore, elements common to the communication system 20 are denoted by the same reference numerals as those in FIG. 1 and description thereof will be omitted as appropriate.

  The communication system 30 includes a selection control method packet transmission control unit 31 as an element corresponding to the transmission rate ratio control method packet transmission control unit 25 in FIG. The packet transmission control unit 31 of the selection control method is the transmission of the packet when the upstream transmission line 5 is vacant, and the upstream data packet waiting for transmission on condition that all the upstream response packets 16 waiting for transmission are transmitted. 15 is transmitted. A flow of packet transmission control by the packet transmission control unit 31 is shown in FIG.

  The packet transmission control unit 31 first determines whether there is a packet waiting for transmission (step S31). This transmission waiting packet determination is the same as the processing in step S21 described above, and is repeated until there is a transmission waiting packet. If there is a transmission waiting packet in step S31, the process proceeds to step S32. In step S32, it is determined whether the upstream transmission path 5 has a vacancy. This transmission path availability determination is repeated until there is an availability. If there is a free space in step S32, the process proceeds to step S33. In step S33, it is determined whether there is an upstream response packet 16 waiting for transmission. If the determination result of step S33 is negative, the process proceeds to step S35. On the other hand, if the determination result of step S33 is affirmative, all the upstream response packets 16 waiting for transmission are continuously transmitted (step S34). Next, it is determined whether there is an upstream data packet 15 waiting for transmission (step S35). If the determination result of step S35 is negative, the process returns to step S31. On the other hand, if the determination result of step S25 is affirmative, the process proceeds to step S36, where all the upstream data packets 15 waiting for transmission are continuously transmitted, and then the process returns to step S31.

  FIG. 6 shows a configuration of a communication system to which the communication control method according to the third embodiment is applied. The communication system 40 in FIG. 6 is the same as the communication system 20 in the first embodiment in its basic configuration. Therefore, elements common to the communication system 20 are denoted by the same reference numerals as those in FIG. 1 and description thereof will be omitted as appropriate.

  The communication system 40 includes a threshold value holding unit 41, and also includes a data length reference control type packet transmission control unit 42 as an element corresponding to the transmission rate ratio control type packet transmission control unit 25 in FIG.

  The threshold holding unit 41 holds a data length threshold set for continuous transmission of the uplink data packet 15.

  The packet transmission control unit 42 of the data length reference control method is a packet transmission when the upstream transmission path 5 is vacant, and the transmission data length in the continuous transmission of the upstream data packet 15 waiting for transmission is the data length described above. Control is performed so that all the upstream response packets 16 waiting for transmission are transmitted every time the threshold value is exceeded. A flow of packet transmission control by the packet transmission control unit 42 is shown in FIG.

  The packet transmission control unit 42 first determines whether there is a packet waiting for transmission (step S41). This transmission waiting packet determination is the same as the processing in step S21 described above, and is repeated until there is a transmission waiting packet. If there is a transmission waiting packet in step S41, the process proceeds to step S42. In step S42, it is determined whether there is a vacancy in the upstream transmission path 5. This transmission path availability determination is repeated until there is an availability. If it becomes empty in step S42, the process proceeds to step S43. In step S43, it is determined whether there is an upstream data packet 15 waiting for transmission. If the determination result of step S43 is negative, the process proceeds to step S47. On the other hand, when the determination result of step S43 is affirmative, the upstream data packet 15 waiting for transmission is continuously transmitted (step S44). Next, the data length is accumulated for the upstream data packet 15 being continuously transmitted (step S45). In subsequent step S46, the result of integration in step S45 is determined. Specifically, it is determined whether the integration result in step S45 exceeds the data length threshold value in the threshold value holding unit 41. If the determination result of step S46 is negative, the process returns to step S45. On the other hand, if the determination result of step S46 is affirmative, the process proceeds to step S47. In step S47, it is determined whether there is an upstream response packet 16 waiting for transmission. If the determination result of step S47 is negative, the process returns to step S41. On the other hand, if the determination result of step S47 is affirmative, the process proceeds to step 48 to continuously transmit all the upstream response packets 16 waiting for transmission, and then returns to step S41.

  As mentioned above, although the form for implementing this invention was demonstrated, these are only typical examples, This invention can be implemented with various forms in the range which does not deviate from the meaning.

It is a figure which shows the structure of the communication system to which the communication control method by 1st Embodiment is applied. It is a figure which shows the flow of a process of the packet storage control in 1st Embodiment. It is a figure which shows the flow of a process of the packet transmission control in 1st Embodiment. It is a figure which shows the structure of the communication system to which the communication control method by 2nd Embodiment is applied. It is a figure which shows the flow of a process of the packet transmission control in 2nd Embodiment. It is a figure which shows the structure of the communication system to which the communication control method by 3rd Embodiment is applied. It is a figure which shows the flow of a process of the packet transmission control in 3rd Embodiment. It is a figure which shows the general structure of the communication system in the past in the case of performing FTP system communication with an asymmetric system line.

Explanation of symbols

2 Downlink node 3 Uplink node 4 Downlink transmission path 5 Uplink transmission path 13 Downlink data packet 14 Downlink response packet 15 Uplink data packet 16 Uplink response packet 22 Response packet dedicated buffer 23 Data packet buffer 25 Transmission rate ratio control system packet Transmission control unit 31 Selection control method packet transmission control unit 42 Data length reference control method packet transmission control unit

Claims (6)

The transmission is performed by transmitting and receiving a data packet for data transmission and a response packet for responding to the reception of the data packet by an upstream node and a downstream node connected to communication lines having different transmission speeds of the upstream transmission line and the downstream transmission line. In a communication control method for communication,
For the uplink response packet that is the response packet transmitted by the uplink node and the uplink data packet that is the data packet transmitted by the uplink node, the uplink response packet is preferentially transmitted to the uplink data packet,
The preferential transmission is performed by a transmission rate ratio control method that controls the transmission rate of the uplink response packet and the uplink data packet to be the same as the ratio of the uplink and downlink transmission rates. Communication control method. The transmission is performed by transmitting and receiving a data packet for data transmission and a response packet for responding to the reception of the data packet by an upstream node and a downstream node connected to communication lines having different transmission speeds of the upstream transmission line and the downstream transmission line. In a communication control method for communication,
For the uplink response packet that is the response packet transmitted by the uplink node and the uplink data packet that is the data packet transmitted by the uplink node, the uplink response packet is preferentially transmitted to the uplink data packet,
A response packet dedicated buffer for storing only the uplink response packet and a data packet buffer for storing the uplink data packet are provided for the upstream node, and in transmission of a packet when an empty space is generated in the upstream transmission path, The preferential transmission is performed by a selection control method that controls to transmit the uplink data packet stored in the data packet buffer on condition that all the uplink response packets stored in the response packet dedicated buffer are transmitted. communication control how to characterized in that it is. The transmission is performed by transmitting and receiving a data packet for data transmission and a response packet for responding to the reception of the data packet by an upstream node and a downstream node connected to communication lines having different transmission speeds of the upstream transmission line and the downstream transmission line. In a communication control method for communication,
For the uplink response packet that is the response packet transmitted by the uplink node and the uplink data packet that is the data packet transmitted by the uplink node, the uplink response packet is preferentially transmitted to the uplink data packet,
A response packet dedicated buffer for storing only the uplink response packet and a data packet buffer for storing the uplink data packet are provided for the upstream node, and a data length threshold is set for continuous transmission of the uplink data packet, In transmission of a packet when there is a vacancy in the upstream transmission path, each time the transmission data length in the continuous transmission of data packets stored in the data packet buffer exceeds the data length threshold, the response packet dedicated communication control how to characterized in that the data length based control system for controlling the to form the preferential transmission to transmit all uplink response packet stored in the buffer. A communication control apparatus provided for the upstream node for use in the communication control method according to claim 1 , comprising a packet transmission control unit for control by the transmission rate ratio control method. Communication control device. A communication control apparatus provided for the upstream node for use in the communication control method according to claim 2 , wherein the packet includes the response packet dedicated buffer and the data packet buffer, and is generated by the upstream node. And a packet storage control unit that controls the storage of packets in the response packet dedicated buffer and the data packet buffer, respectively, and further includes a packet transmission control unit for control by the selection control method. A communication control device. A communication control apparatus provided for the upstream node for use in the communication control method according to claim 3 , wherein the response packet dedicated buffer, the data packet buffer, and the data length threshold are stored. A threshold storage unit, a packet storage control unit that determines a packet generated in the upstream node and controls storage of the packet in each of the response packet dedicated buffer and the data packet buffer, and further includes the data A communication control apparatus comprising a packet transmission control unit for control by a long reference control method.

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