JP2005159922A - Communication unit, communication system, and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase traffic throughput in a communication system and the like, in which assembly method is adopted. <P>SOLUTION: An assembly number is set by one assembly so that the assembly number corresponds to RWIN size information of a receive terminal. A packet of a connection-less type protocol and a packet of a connection type protocol are subjected to multi-flow assembly under prescribed references. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a communication apparatus, a communication system, and a communication method for performing communication via a network, for example. More specifically, for example, in packet communication, a communication apparatus, communication system, and communication for assembling packet data and transmitting it. Regarding the method.

  In packet transfer transferred to a network, transfer is often performed with a packet having a size much smaller than that of an MTU (Max Transmission Unit), which increases the load on the router. An assembly method has been proposed as a method for reducing the load on the router (see, for example, Patent Document 1). The assembly method is a method of transferring a plurality of packets into a single packet in a communication device such as an edge router when transferring the packets. As a result, the number of packets flowing through the network can be reduced, so that the header processing load in the router can be reduced.

  However, in the assembly method, the packets are kept waiting in the buffer in the router until the packets that are the unit of assembly are gathered, so that there is a possibility that the transfer rate is lowered. For this reason, an assembly method has been proposed in which the target of assembly is expanded not only to packets output from the same terminal but also to packets flowing through two or more different terminals that share a common edge router (this is called This is referred to as “multi-flow assembly system.” For example, see Non-Patent Document 1. According to this multi-flow assembly method, the waiting time at the edge router is shortened as a whole because the number of types of packets to be assembled is large, and a decrease in transfer rate is suppressed. Note that a method for assembling only packets output from the same terminal is called a “single flow assembly method”.

JP 2003-304284 A (paragraphs [0038] to [0045], FIG. 3 to FIG. 8 and others) “Proposal of multi-flow assembly method” Ryosuke Tanioka, Yoshinori Uranishi, Toshikatsu Kanda, Kazunori Shimamura, September 2001, Shikoku Branch Association

  However, even in the multi-flow assembly method, if transmission of one of a plurality of packets to be assembled or transmission of an acknowledgment signal is delayed for some reason, the packet is made to wait at the router as in the single-flow assembly method and transferred. The speed will decrease.

  In the case of the assembly method, a terminal that receives a packet outputs a confirmation response (ACK) based on a data communication unit that requires confirmation, such as a TCP window size (RWIN (Receive Window) Size). There is a problem that transmission delay may occur due to the difference in unit. This problem will be described based on the following example. It is assumed that the RWIN size of the application that is used by the terminal that receives the packet is the size of three packets to be transmitted, and therefore ACK is output every time three packets are received. On the other hand, in the edge router, it is assumed that assembly is performed every four packets by a single flow assembly method. When the RWIN size and the number of assemblies do not match in this way, if a retransmission request is issued from the reception side to the transmission side, the transfer speed may decrease due to the necessity of re-assembly of the assembly. Such a situation can similarly occur even when the multi-flow assembly method is used.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to improve traffic throughput in a communication apparatus, communication method, and communication system that employ an assembly method.

  To achieve the above object, a communication device according to a first invention of the present application according to the present invention executes an assembly that collectively transfers a plurality of data communication units transmitted from a transmission terminal as one data communication unit. An execution unit, a reception window information acquisition unit that acquires reception window information related to the size of the reception window in the reception terminal that receives the data communication unit, and one time in the assembly execution unit based on the acquired reception window information An assembly number setting unit that sets the number of assemblies as the number of data communication units collected in the assembly, and the assembly execution unit executes the assembly based on the assembly number set by the assembly number setting unit It is characterized by that.

  To achieve the above object, the communication device according to the second invention of the present application collects data communication units received from a plurality of terminals and transfers them as one data communication unit (for example, packet data, etc., the same applies hereinafter). In a communication device capable of executing assembly, an extraction unit that extracts a data communication unit of a connectionless protocol from data communication units from the plurality of terminals, and a data communication of the connectionless protocol extracted by the extraction unit A determination unit that determines whether a unit is suitable for a multiflow assembly together with a data communication unit of another connection-type protocol, and a determination that the determination unit is suitable for a multiflow assembly In this case, the data communication unit of the connectionless protocol is changed to the other connection. The data communication unit of the connection protocol and the data communication unit of the connectionless protocol when the determination unit determines that it is not suitable for the target of the multiflow assembly. And an assembly execution unit that executes the multiflow assembly using only the data communication unit of the other connection type protocol as a target of the multiflow assembly.

  To achieve the above object, a communication system according to a third invention of the present application includes an assembly execution unit that collectively transfers a plurality of data communication units transmitted from a transmission terminal, and the assembled data A communication system including a plurality of edge routers including a reassembly execution unit that disassembles a communication unit into the plurality of data communication units and transfers the data to a receiving terminal as a destination, wherein the edge router includes the data communication A reception window information acquisition unit that acquires reception window information related to the size of the reception window in a reception terminal that receives the unit, and a data communication unit that is collected in one assembly in the assembly execution unit based on the acquired reception window information An assembly number setting unit for setting the number of assemblies as the number of Buri execution unit is characterized in that the execution of the assembly based on the number of assemblies which are set by the assembly number setting unit.

  To achieve the above object, a communication system according to a fourth invention of the present application includes an assembly execution unit that collectively transfers a plurality of data communication units transmitted from a transmission terminal, and the assembled data A communication system including a plurality of edge routers including a reassembly execution unit that disassembles a communication unit into the plurality of data communication units and transfers the data to a receiving terminal as a destination, wherein the edge router includes the data communication An extraction unit that extracts a data communication unit of a connectionless protocol from the units, and a data communication unit of a connectionless protocol extracted by the extraction unit is combined with a data communication unit of another connection type protocol in a multiflow assembly. A determination unit that determines whether or not the target is suitable based on a predetermined criterion. When the assembly execution unit determines that the determination unit is suitable for a target of multiflow assembly, the assembly execution unit performs a multiflow operation on the data communication unit of the connectionless protocol and the data communication unit of the other connection type protocol. If it is determined as an assembly target and the determination unit determines that it is not suitable for a multiflow assembly, the data communication unit of the connectionless protocol is excluded from the target of the multiflow assembly, and the data of the connection protocol The present invention is characterized in that the multiflow assembly is executed with only the communication unit as a target of the multiflow assembly.

  To achieve the above object, a communication method according to a fifth invention of the present application includes an assembly step of executing an assembly that collectively transfers a plurality of data communication units transmitted from a transmission terminal as one data communication unit; A communication method comprising the steps of: transferring an assembled data communication unit; and reassembling the disassembled data communication unit into the plurality of data communication units and executing reassembly for transmitting to the receiving terminal. A step of acquiring reception window information relating to a size of a reception window in a reception terminal that receives the data communication unit, and data assembled in one assembly in the assembly step based on the acquired reception window information Ascension that sets the number of assemblies as the number of communication units And re-setting step, the number of assembly set in said assembly number setting step is characterized in that a step of performing the assembly step.

  To achieve the above object, a communication method according to a sixth invention of the present application is a multi-flow assembly that executes a multi-flow assembly that collectively transfers a plurality of data communication units transmitted from a plurality of transmission terminals as one data communication unit. A communication method comprising: a flow assembly step; a step of transferring the assembled data communication unit; and a reassembly step of performing reassembly for disassembling the assembled data communication unit into the plurality of data communication units. A step of extracting a data communication unit of a connectionless protocol from the plurality of data communication units, and the extracted data communication unit of the connectionless protocol is combined with a data communication unit of another connection protocol Suitable for multi-flow assembly Determining whether or not based on predetermined criteria, and if determined to be suitable for multiflow assembly, the data communication unit of the connectionless protocol and the other connection protocol If it is determined that the data communication unit is the target of the multiflow assembly and is not suitable for the multiflow assembly, the data communication unit of the connectionless protocol is excluded from the target of the multiflow assembly. The multiflow assembly step is executed only for a data communication unit of the connection type protocol as a target of multiflow assembly.

  According to the first, third, and fifth inventions, the reception window information related to the reception window size of the reception terminal that receives the data communication unit of the connection type protocol that is the target of the multiflow assembly is acquired, and based on this information. To set the number of assemblies. Thereby, the number of assemblies and the reception window size of the receiving terminal are matched, and the traffic throughput is improved.

  In the second, fourth and sixth inventions, the data communication unit of the connectionless protocol is continuously transmitted to the receiving terminal without waiting for a response confirmation from the receiving terminal. This is made by paying attention to the fact that there is little variation in the transmission interval of the communication unit. That is, according to the second, fourth and sixth inventions, the data communication unit of the connectionless protocol is multiflow assembled with the data communication unit of the connection type protocol under a predetermined standard. As a result, the standby time for each data communication unit is shortened, and the traffic throughput can be improved.

  Next, a communication system according to an embodiment of the present invention will be described in detail with reference to the drawings. In this communication system, as shown in FIG. 1, terminals 11 to 16 perform communication via a network 20. The network 20 includes edge routers 21 to 24 to which the terminals 11 to 16 are connected and a core router 25 that relays these. The edge routers 21 to 24 are located at the contact points with the terminals 11 to 16 around the network 20. The core router 25 has a role of relaying packets transmitted and received between the edge routers 21 to 24. Further, as will be described later, the edge routers 21 to 24 have an assembly function that collects a plurality of types of packets into one packet and a reassembly function that disassembles the assembled packets.

  The assembly includes a single flow assembly that assembles only packets from the same terminal into one packet, and a multi-flow assembly that assembles packets from different terminals that share a common edge router into one packet. . As will be described later, these edge routers 21 to 24 are configured to selectively execute any one of a multiflow assembly, a single flow assembly, and a normal transfer method (transfer control of received packet data one by one) as appropriate. Is done.

  The number of terminals 11 to 16, the edge routers 21 to 24, and the core router 25 shown in FIG. 1, the connection relationship, and the like are merely examples, and it goes without saying that the present invention is not limited thereto. For example, in FIG. 1, each of the terminals 11 to 16 is directly connected to the edge routers 21 to 24, but the terminals 11 to 16 and the edge routers 21 to 24 are connected via a relay device such as another router or a network. Are naturally included within the scope of the present invention.

  In the following description of the embodiment, a terminal that transmits data among the terminals 11 to 16 is referred to as a “transmission terminal”, and a terminal that receives data is referred to as a “reception terminal”. Any of the terminals 11 to 16 functions as both a transmission terminal and a reception terminal. Further, the terminals 11 to 14 of the terminals 11 to 16 perform packet communication by executing FTP (File Transfer Protocol) on the TCP protocol, which is a connection type protocol, unless otherwise specified (the present invention). However, the present invention is not limited to this, and it goes without saying that the present invention is applicable to the case where another application is executed.

  On the other hand, it is assumed that the terminals 15 and 16 are performing packet communication mainly by the UDP protocol, which is a connectionless protocol, in order to transmit stream data of audio data and moving image data. Unlike the TCP protocol, the UDP protocol does not have functions such as sequence control based on an acknowledgment number and continuous transmission by window control. Therefore, although the reliability is reduced, high-speed communication is possible. Here, it is assumed that the terminal is mainly a terminal that performs communication based on the TCP protocol or the UDP protocol only to show an example, and the present invention naturally also applies to a case where both the TCP protocol and the UDP protocol are used in one terminal. Applicable.

  Next, details of the configuration of the edge routers 21 to 24 constituting the network 20 will be described with reference to FIG. As illustrated in FIG. 2, the edge routers 21 to 24 include an input port IP, an input queue IQ, a type determination unit 31, an assembly suitability determination unit 32, an assembly execution unit 33, an RWIN size determination unit 34, An assembly number setting unit 35, a reassembly execution unit 36, a transfer control unit 37, an assembly control unit 38, an output queue OQ, and an output port OP are provided.

  The input port IP is a terminal for inputting packets transmitted from the terminals 11 to 16 and the core router 25. The input queue IQ is a storage unit for temporarily storing and waiting for a packet input from the input port IP. The type determination unit 31 is a part that determines the type of communication protocol of a packet input from the input queue IQ. Specifically, the type determination unit 31 is a packet transmitted by the TCP protocol, which is a connection type protocol, or a connectionless type It is determined based on the header included in the packet whether it is a packet transmitted by the UDP protocol which is a protocol or an assembled packet.

  The assembly suitability determination unit 32 determines whether or not the packet determined by the type determination unit 31 to be a UDP protocol packet is suitable for multi-flow assembly together with other TCP protocol packets. It is. This determination can be performed, for example, based on whether or not the difference between the UDP protocol packet transmission interval and the average transmission interval of the other TCP protocol packets is equal to or less than a predetermined value.

  The assembly execution unit 33 has a function of assembling a packet, and is configured to selectively execute either a single flow assembly method or a multiflow assembly method in accordance with an instruction from an assembly control unit 38 to be described later. The assembly execution unit 33 includes an assembly buffer (not shown) for temporarily storing these packets. The details of the assembly execution procedure are known as in the above-mentioned Patent Document 1, and thus detailed description thereof is omitted.

  When the multi-flow assembly method is executed, TCP protocol packets from different terminals are assembled into one packet in the assembly execution unit 33. If there is a UDP protocol packet that is determined to be suitable for multiflow assembly by the assembly suitability determination unit 32, the packet is also subject to multiflow assembly.

  The RWIN size determination unit 34 determines the size of the reception window (RWIN) for the application (such as FTP) being used by each terminal based on the window data included in the header of the transmitted packet. In addition, even if the RWIN is the same terminal, it is usually different for each application. The assembly number setting unit 35 performs assembly in the assembly execution unit 33 based on the size of the RWIN determined by the RWIN size determination unit 34 and the type of assembly method (single flow assembly method or multiflow assembly method) to be executed. Set the number. Details will be described later.

  The reassembly execution unit 36 receives the assembled packet from the core router 25 via the input port IP and the input queue IQ, and executes reassembly for disassembling into individual packets before assembly.

  The transfer control unit 37 refers to the IP address indicated in the header added to the packet, and controls to transfer the packet to the output queue OQ corresponding to the IP address. Transfer of the packet assembled by the assembly execution unit 33 is controlled based on the IP address indicated in the additional header added at the time of assembly. Further, packets that are not subjected to assembly by the assembly execution unit 33 and packets reassembled by the reassembly execution unit 36 are controlled to be transferred based on the IP address indicated in the IP packet. The packets transferred to the output queue OQ are sequentially output to the downstream core router 25 or the terminals 11 to 16 via the output port OP.

  The assembly control unit 38 can selectively execute any one of the normal transfer method, the single flow assembly method, and the multi-flow assembly method, so that the type determination unit 31, the assembly suitability determination unit 32, the assembly execution unit 33, and the RWIN size The determination unit 34 and the assembly number setting unit 35 are controlled. Details of the control will be described later.

Next, the operation of this communication system will be described with reference to the flowcharts shown in FIGS. Below, (1) when the single flow assembly method is executed, (2) when the multiflow assembly is executed, and (3) when the normal transfer method is executed, the description will be divided.
(1) When the single flow assembly method is executed The operation when the single flow assembly method is executed will be described with reference to the flowchart shown in FIG. The assembly control unit 38 outputs a command signal for instructing the assembly execution unit 33 to execute the single flow assembly method, and stops the functions of the type determination unit 31 and the assembly suitability determination unit 32.
Upon receipt of this command signal, the assembly execution unit 33 starts execution of a single flow assembly method for assembling the packets received from the terminals 11 to 14 for each identical transmission terminal, and sends the assembled packets to the transfer control unit 37. Output (S1 in FIG. 3).

  The RWIN size determination unit 34 determines the size of the RWIN related to the application (here, FTP) used by the receiving terminal that is the destination of the packet to be assembled (S2), and the assembly number setting unit 35 determines The number of assemblies that matches the RWIN size is set (S3). For example, when assembling a packet transmitted from the terminal 11 to the terminal 13, the RWIN size determination unit 34 determines the FTP of the terminal 13 based on the RWIN information indicated in the header of the packet returned from the terminal 13 to the terminal 11. Determine the size of the RWIN. The assembly number setting unit 35 sets the number of assemblies that matches the RWIN size of the FTP of the terminal 13. Thereby, the number of assemblies is matched with the RWIN size of the receiving terminal, and the traffic throughput is improved.

  Note that the functions of the RWIN size determination unit 34 and the assembly number setting unit 35 are used in the case of a protocol that does not correspond to the RWIN or when it is considered that the influence on the transmission speed due to the mismatch of the RWIN size and the number of assemblies is small. Alternatively, only the assembly execution unit 33 may function.

(2) When the multiflow assembly method is executed Next, the operation when the multiflow assembly is executed will be described with reference to the flowchart shown in FIG. Here, focusing on the edge router 21, description will be made on the assumption that TCP protocol packets P 5 and P 6 are transmitted from the terminals 11 and 12 to the edge router 21, and a UDP protocol packet P 7 is transmitted from the terminal 15.

  The assembly execution unit 33 starts multi-flow assembly of TCP protocol packets P5 and P6 based on an instruction from the assembly control unit 38 (S11 in FIG. 4). Further, the type determination unit 31 and the assembly suitability determination unit 32 are operated by a control signal from the assembly control unit 38. The type determination unit 31 extracts the UDP protocol packet P7 (S12), and the assembly suitability determination unit 32 determines whether this packet P7 is suitable for multi-assembly with the packets P5 and P6. (S13). As described above, this determination may be executed based on whether the difference between the transmission interval of the UDP protocol packet P7 and the average transmission interval of the TCP protocol packets P5 and P6 is equal to or less than a predetermined value. it can.

  When it is determined that the packet P7 is suitable for the multi-assembly target (YES), the UDP protocol packet P7 is selected as the multi-flow assembly target with the TCP protocol packets P5 and P6 (S14). ). Thereafter, the RWIN size determination unit 34 determines the total size of the RWIN relating to the application in use of the receiving terminal that is the destination of the assembled packets P5, P6, and P7 (S15).

  Then, the number of assemblies that matches the determined total size of RWIN is set by the assembly number setting unit 35 (S16). Thereby, the number of assemblies is matched with the RWIN size of the receiving terminal, and the traffic throughput is improved. Also, the UDP protocol packet P7, which is a connectionless protocol, is multi-flow assembled together with the TCP protocol packets P6, P7, which is a connection protocol, thereby reducing the waiting time in the router of the packet and improving the traffic throughput. Figured. This is because the connectionless protocol packet is continuously transmitted to the receiving terminal without waiting for a response confirmation from the receiving terminal, and therefore, the variation in the packet transmission interval is less than that of the connection type protocol. If it is considered that the influence on the transmission speed due to the mismatch between the total RWIN size and the number of assemblies is small, the functions of the RWIN size determination unit 34 and the assembly number setting unit 35 are stopped, and the assembly execution unit 33 Only the flow assembly may be executed.

  On the other hand, if it is determined that the packet P7 is not suitable for multi-assembly with the packets P5 and P6 (NO), the packet P7 is not subject to multi-assembly (S15), and the TCP protocol packet P5 And P6 only are targeted for multiflow assembly. In this case, the RWIN size determination unit 34 determines the total of the RWIN sizes of the applications (here, FTP) in use by the receiving terminal that is the destination of the packets P5 and P6 (S18). For example, when the packet P5 has the terminal 13 as the receiving terminal and the packet P6 has the terminal 14 as the receiving terminal, the total value of the FTP RWIN size of the terminal 13 and the FTP RWIN size of the terminal 14 is the RWIN size determination unit 34. Is determined. The assembly number that matches the total value of the RWIN sizes determined in this way is set by the assembly number setting unit 35 (S19). Thereby, the number of assemblies is matched with the RWIN size of the receiving terminal, and the traffic throughput is improved.

(3) When the normal transfer method is executed The assembly control unit 38 includes a type determination unit 31, an assembly suitability determination unit 32, an assembly execution unit 33, an RWIN size determination unit 34, an assembly number setting unit 35, and a reassembly execution unit 36. Stop function. Thereby, the packets transmitted from the terminals 11 to 16 are directly transmitted to the transfer control unit 37 without being assembled, and the normal transfer method for performing transfer control for each packet is executed.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to these, In the range which does not deviate from the meaning of invention, various addition, change, substitution, etc. are possible. For example, in the above embodiment, the multi-flow assembly of the UDP protocol packet and the TCP protocol packet has been described. However, the present invention is not limited to UDP or TCP, and any connection type protocol or connectionless type protocol packet can be used. Applicable to multi-flow assembly. In the above embodiment, the multi-flow assembly of one connectionless protocol packet (P7) and the connection protocol packet (P5, P6) has been described. It is also possible to simultaneously target packets for multiflow assembly. For example, there are a plurality of types of UDP protocol packets P7 and P8 transmitted from different terminals, and when both transmission intervals match the average transmission interval of TCP protocol packets P5 and P6, both of them are If only one of them matches, only one of them can be the target of the multiflow assembly.

1 shows a configuration of a communication system according to the present embodiment. It is a block diagram which shows the detail of a structure of the edge routers 21-24 which comprise the communication system shown in FIG. It is a flowchart which shows the one aspect | mode of operation | movement of the communication system shown in FIG. It is a flowchart which shows the one aspect | mode of operation | movement of the communication system shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11-16 ... Terminal, 20 ... Network, 21-24 ... Edge router, 25 ... Core router, IP ... Input port, IQ ... Input queue, 31 ... Type determination part 32 ... Assembly suitability determination unit, 33 ... Assembly execution unit, 34 ... RWIN size determination unit, 35 ... Assembly number setting unit, 36 ... Reassembly execution unit, 37 ... Transfer Control unit 38 ... Assembly control unit, OQ ... Output queue, OP ... Output port.

Claims (9)

An assembly execution unit that executes an assembly that collectively transfers a plurality of data communication units transmitted from a transmission terminal as one data communication unit;
A reception window information acquisition unit that acquires reception window information related to a size of a reception window in a reception terminal that receives the data communication unit;
An assembly number setting unit that sets the number of assemblies as the number of data communication units collected in one assembly in the assembly execution unit based on the acquired reception window information,
The communication apparatus according to claim 1, wherein the assembly execution unit executes assembly based on the number of assemblies set by the assembly number setting unit.       The communication apparatus according to claim 1, wherein the reception window information acquisition unit acquires the reception window information from a header of a data communication unit transmitted from the reception terminal to the transmission terminal. In a communication apparatus capable of executing a multi-flow assembly for transferring data communication units received from a plurality of terminals as one data communication unit,
An extraction unit for extracting a data communication unit of a connectionless protocol from data communication units from the plurality of terminals;
A determination unit for determining whether a data communication unit of the connectionless protocol extracted by the extraction unit is suitable for being a target of multiflow assembly together with a data communication unit of another connection type protocol;
When it is determined that the determination unit is suitable for the target of multiflow assembly, the data communication unit of the connectionless protocol is the target of multiflow assembly together with the data communication unit of the other connection type protocol, If the determination unit determines that the data communication unit is not suitable for the multiflow assembly, the data communication unit of the connectionless protocol is excluded from the target of the multiflow assembly, and only the data communication unit of the other connection protocol is used. An assembly execution unit that executes a multiflow assembly as a target of the multiflow assembly.       4. The determination unit according to claim 3, wherein the determination unit performs the determination based on a difference between a transmission interval of the data communication unit of the connectionless protocol and a transmission interval of the data communication unit of the other connection type protocol. Communication device. A reception window information acquisition unit for acquiring reception window information related to the size of the reception window in a reception terminal that receives a data communication unit of the connection-type protocol that is a target of multiflow assembly;
An assembly number setting unit that sets the number of assemblies as the number of data communication units collected in one multiflow assembly in the assembly execution unit based on the acquired reception window information,
The communication apparatus according to claim 3, wherein the assembly execution unit further executes the assembly based on the number of assemblies set by the assembly number setting unit. An assembly execution unit that collectively transfers a plurality of data communication units transmitted from a transmission terminal, and disassembles the assembled data communication unit into the plurality of data communication units to be a destination terminal as a destination. A communication system including a plurality of edge routers including a reassembly execution unit for transferring,
The edge router is
A reception window information acquisition unit that acquires reception window information related to a size of a reception window in a reception terminal that receives the data communication unit;
An assembly number setting unit configured to set the number of assemblies as the number of data communication units collected in one assembly in the assembly execution unit based on the acquired reception window information. The assembly execution unit includes the assembly A communication system, wherein assembly is executed based on the number of assemblies set by a number setting unit. An assembly execution unit that collectively transfers a plurality of data communication units transmitted from a transmission terminal, and disassembles the assembled data communication unit into the plurality of data communication units to be a destination terminal as a destination. A communication system including a plurality of edge routers including a reassembly execution unit for transferring,
The edge router is
An extraction unit for extracting a data communication unit of a connectionless protocol from the data communication unit;
It is determined based on a predetermined criterion whether or not the data communication unit of the connectionless protocol extracted by the extraction unit is suitable for being subjected to multiflow assembly together with the data communication unit of other connection type protocol. A determination unit, and
The assembly execution unit determines that the data communication unit of the connectionless protocol and the data communication unit of the other connection type protocol are multiplexed when the determination unit determines that it is suitable for the target of multiflow assembly. If it is determined that the determination unit is not suitable for multiflow assembly as a target of flow assembly, the data communication unit of the connectionless protocol is excluded from the target of multiflow assembly. A communication system configured to execute a multi-flow assembly with only a data communication unit as a target of the multi-flow assembly. An assembly step for executing an assembly that collectively transfers a plurality of data communication units transmitted from a transmission terminal as one data communication unit;
Transferring the assembled data communication unit;
A reassembly step of performing reassembly for disassembling the assembled data communication unit into the plurality of data communication units and transmitting the unit to a receiving terminal,
Obtaining reception window information relating to the size of the reception window at the reception terminal that receives the data communication unit;
An assembly number setting step for setting the number of assemblies as the number of data communication units collected in one assembly in the assembly step based on the received reception window information, and the number of assemblies set in the assembly number setting step And a step of executing the assembly step. A multi-flow assembly step for executing a multi-flow assembly that collectively transfers a plurality of data communication units transmitted from a plurality of transmission terminals as one data communication unit;
Transferring the assembled data communication unit;
A reassembly step for performing reassembly for disassembling the assembled data communication unit into the plurality of data communication units,
Extracting a data communication unit of a connectionless protocol from the plurality of data communication units;
Determining whether or not the extracted data communication unit of the connectionless protocol is suitable for being subjected to multiflow assembly together with the data communication unit of another connection type protocol, based on a predetermined criterion;
When it is determined that it is suitable for a multiflow assembly, the data communication unit of the connectionless protocol and the data communication unit of the other connection protocol are targeted for the multiflow assembly. If it is determined that it is not suitable for the flow assembly, the data communication unit of the connectionless protocol is excluded from the target of the multiflow assembly, and only the data communication unit of the connection type protocol is included in the multiflow assembly. A communication method characterized in that the multi-flow assembly step is executed as a target.

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