WO2015022809A1 - Communication device and transmission band control method - Google Patents

Abstract

In the present invention, even if communication having a large amount of communication and communication having a small amount of communication share the same communication line, while securing a band for the communication having a small amount of communication, the communication having a large amount of communication can fairly and completely use the remaining band. For each connection, a buffer accumulates packets transmitted to a second device via a network from a first device. A band control unit (1015) controls the transmission band for each connection in accordance with a set control band of each connection. A band control unit (1015) imposes an upper limit for the control band on the basis of the packet accumulation amount for each connection accumulated in the buffer, and the communication lag time for each connection.

Description

Communication apparatus and transmission bandwidth control method

The present invention relates to a communication apparatus and a transmission band control method, and more particularly to a communication apparatus and a transmission band control method for controlling a communication band between terminals.

As a communication network between bases used for the cloud or the like, it is common to use a WAN (Wide Area Network) using an IP-VPN (Internet Protocol-Virtual Private Network) technology or the like. When a terminal at a certain base communicates with a terminal at another base, communication is performed via a line connecting the local LAN and the WAN and a line connecting the WAN and the separate LAN. Is called. In these lines, the usable bandwidth is limited by the contract bandwidth.
TCP is generally used for communication between terminals. In TCP communication, the reception terminal notifies the transmission terminal of the position of the received data with respect to the data transmitted by the transmission terminal. When the position of the received data that is notified of feedback does not increase, the transmitting terminal determines that the discard is detected.
Furthermore, the transmitting terminal manages a parameter called a congestion window size (data size that can be transmitted without being notified from the receiving terminal), depending on whether there is RTT (Round Trip Time) or discard detection. To change the congestion window size.
By determining that the network is congested at the time of discard detection or when the RTT is increased, and reducing the window size, the transmission band is indirectly decreased to avoid network congestion. Further, when there is no discard or when the RTT decreases, it is determined that the network is free, and the window size is increased, thereby indirectly increasing the transmission bandwidth and effectively using the network bandwidth.
The larger the RTT, the more difficult it is to increase the window size. When two or more communications having different RTTs share one line, an unfairness may occur in the allocated bandwidth. There is also a technique for controlling the transmission rate of a relay connection of a communication apparatus according to the number of connections being relayed (Patent Document 1).

International Publication No. 05/006664

If the transmission rate of the relay connection is controlled according to the number of connections, the amount of traffic and RTT are not taken into account, so the bandwidth to which the communication with a small amount of communication cannot be used and the communication with a large amount of communication is redundant. There was a problem that could not use the bandwidth of.
In view of the above points, the present invention secures a communication bandwidth with a small amount of communication and a large amount of communication even when a communication with a large amount of communication and a communication with a small amount of communication share the same communication line. It is an object of the present invention to provide a communication device and a transmission band control method that enable communication to use up the remaining bandwidth and effectively use the line bandwidth.

In order to solve the above problems, in one aspect of the present invention,
A buffer for storing packets transmitted from the first device to the second device via the network for each connection;
A bandwidth control unit that controls the transmission bandwidth of each connection according to the control bandwidth of each connection to be set,
The bandwidth control unit is provided with a communication device that limits the upper limit of the control bandwidth for each connection based on an accumulation amount of packets of each connection accumulated in the buffer and a communication delay time of each connection. .
According to the above-described aspect, even when a communication with a large amount of communication and a communication with a small amount of communication share the same communication line, a communication band with a large amount of communication remains in the remaining band while securing a band for a communication with a small amount of communication It is possible to use up all of the bandwidth and effectively use the line bandwidth.
In another aspect of the present invention,
Storing packets transmitted from the first device over the network to the second device for each connection;
The step of controlling the transmission bandwidth of each connection according to the set control bandwidth of each connection, and for each connection, based on the accumulated amount of packets of each connection accumulated in the buffer and the communication delay time of each connection A transmission bandwidth control method including the step of obtaining an upper limit value of the control bandwidth.
In yet another aspect of the present invention,
A buffer for storing packets transmitted from the first device to the second device via the network for each connection;
With a bandwidth controller,
The bandwidth control unit
Limit the upper limit bandwidth of each connection based on the number of connections in which the data size of the packet stored in the buffer is equal to or greater than a predetermined threshold, or
The transmission bandwidth related to packets transmitted from the first device to the second device via the network is managed for each predetermined interval, and the transmission bandwidth of the interval is based on the number of connections equal to or greater than a predetermined threshold. A communication device that limits the upper limit bandwidth of each connection is provided.

According to the present invention, even when a communication with a large amount of communication and a communication with a small amount of communication share the same communication line, a communication band with a large amount of communication remains in the remaining band while securing a band of communication with a small amount of communication. It is possible to use up all of the bandwidth and effectively use the line bandwidth.

The system block diagram which has the apparatus in this Embodiment. The block diagram of the apparatus 200 in this Embodiment. Explanatory drawing of a band equal division | segmentation. Explanatory drawing of the band division | segmentation which considered the communication amount. Explanatory drawing of the pointer of a buffer. Packet format diagram. The format diagram of a state table. The conceptual diagram explaining the meaning of the value which a state table hold | maintains. The block diagram of a proxy part. The block diagram of a TCP part (WAN side). The block diagram of a TCP part (LAN side). Explanatory drawing of congestion control using the change rate of a discard rate. FIG. 6 is a high-level (conceptual) flowchart for updating a control band. The flowchart figure of the part which increases a control zone | band. The detailed flowchart figure which updates a control zone | band. The flowchart figure which calculates the weight of communication amount. The flowchart figure which calculates the upper limit zone | band of each connection based on the weight of traffic. The other format figure of a state table.

A typical form for carrying out the present invention is as follows. Example 1 describes a basic form.

First, the problem to be solved by the present invention will be described with reference to FIGS.
FIG. 1 shows a configuration diagram of a relay system to which the communication apparatus of the present embodiment is applied.
Communication devices (also referred to as relay devices, hereinafter simply referred to as devices) 200A to 200C are installed on communication lines that connect LANs 110, 120, and 130 and WAN 140 in a plurality of bases. The apparatuses 200A to 200C and the WAN 140 are connected by access lines 191, 192, and 193. A plurality of terminals 111 to 113, 121 to 123, and 131 to 133 are connected to the LANs 110, 120, and 130 at each site. Further, the number of terminals, devices, and networks may be an appropriate number other than illustrated.
FIG. 3 is an explanatory diagram of band division when communication with a large amount of communication and communication with a small amount of communication share the same line.
The terminals 111 and 112 communicate via the device 200A. When the communication amount from the terminal 111 to the WAN 140 is large and the communication amount from the terminal 112 to the WAN 140 is small, the communication of the terminal 111 having a large communication amount and the communication of the terminal 112 having a small communication amount are performed on the access line 191. Will share.
In such a case, if the device 200A allocates a half of the maximum bandwidth 300 to each communication, the communication of the terminal 111 having a large communication amount can use all the allocated bandwidth 302, while the communication of the terminal 112 having a small communication amount. In some cases, the bandwidth allocated for communication cannot be used up (301), and many unused bandwidths 303 are generated, and the bandwidth cannot be used effectively.
The present invention relates to transmission band control in apparatuses 200A to 200C. Even when communication with a large amount of communication and communication with a small amount of communication share the same communication line, the bandwidth of the communication with a small amount of communication is reduced. The purpose is to enable the communication with a large amount of communication to use up the remaining bandwidth while securing the bandwidth, and to effectively use the bandwidth.

FIG. 2 shows a block diagram of apparatuses 200A to 200C of the present embodiment.
The apparatus 200 includes, for example, a WAN-side and LAN-side network interface (201/2111) that transmits / receives packets to / from an external WAN / LAN network, a TCP packet that is not targeted for acceleration, a UDP packet other than TCP, and an ARP packet. And the like (202/210), a TCP processing unit 1000 that performs control for TCP communication on the WAN side, a TCP processing unit 1100 that performs control for TCP communication on the LAN side, and the WAN side N transmission buffers 511 and N reception buffers 501 managed by the TCP processing unit 1000, N transmission buffers 510 and N reception buffers 500 managed by the TCP processing unit 1100 on the LAN side, and transmission / reception buffers Proxy 900 for transferring data between them and N entries A state table (state storage region) 700 having a, with an external terminal 240 includes an interface 230 for exchanging information such as the contents of the state table 700. The above-mentioned N pieces may be different numbers. For example, the transmission buffer and the reception buffer accumulate packets between terminals for each connection.
The TCP processing units 1000 and 1100 and the proxy 900 will be described in detail later and will be outlined here.

The LAN-side TCP processing unit 1100 includes a transmission history update unit 1105, a packet retransmission unit 1104, a reception history update unit 1106, a distribution unit 1108, and an aggregation unit 1113. The reception history update unit 1106 accumulates the received packet data in the LAN side reception buffer 500. Further, the reception history update unit 1106 updates the information of the buffer management pointers (709 to 711) in the state table 700 according to the accumulated data. Further, the reception history update unit 1106 returns an ACK packet describing the position of the received data via the aggregation unit 1113. The packet retransmission unit 1104 retransmits the packet according to the ACK number of the received ACK packet and updates the information of the buffer management pointers (715 to 717) in the state table 700. The transmission history update unit 1105 transmits the transmission data read from the LAN-side transmission buffer 510 as a packet, and updates the information of the buffer management pointers (715 to 717) in the state table 700 according to the read data.
The WAN TCP processing unit 1000 includes a transmission bandwidth control unit 1015, a transmission history update unit 1005, a packet retransmission unit 1004, a reception history update unit 1006, a distribution unit 1016, and an aggregation unit 1012. The reception history update unit 1006 accumulates the received packet data in the WAN reception buffer 501. Further, the reception history update unit 1006 updates the information of the buffer management pointers (722 to 724) in the state table 700 according to the accumulated data. Further, the reception history update unit 1006 returns an ACK packet describing the position of the received data via the aggregation unit 1012. The packet retransmission unit 1004 retransmits the packet according to the ACK number of the received ACK packet and updates the information of the buffer management pointers (728 to 730) in the state table 700. The transmission band control unit 1015 accumulates information on the transmission band, the retransmission band, and the number of received ACKs in the state table 700. The transmission history update unit 1005 transmits the transmission data read from the WAN side transmission buffer 511 as a packet, and updates the information of the buffer management pointers (728 to 730) in the state table 700 according to the read transmission data size. To do.
The proxy 900 includes a data reading unit (901, 906), a data processing unit (902, 905), and a data writing unit (903, 904). The data reading units (901, 906) update the information of the buffer management pointers (709 to 711, 722 to 724) of the state table 700 according to the data size read from the reception buffer (500, 501). The data writing units (903, 904) update the information of the buffer management pointers (715 to 717, 728 to 730) in the state table 700 according to the data size written to the transmission buffers (510, 511).

FIG. 5 is an explanatory diagram of pointers for transmission / reception buffer management. In this figure, data is written from left to right and read from left to right.
The reception buffers 500 and 501 include a pointer right_recv (711 and 724) indicating the head of the received data, a pointer left_recv (710 and 723) indicating a boundary between the aligned data and the unaligned data, and the proxy 900 has already been read. It manages left_rbuf (709, 722) indicating the boundary between data and data that has not yet been read.
The pointer right_recv (711, 724) indicating the head of the received data has no loss, and when data is received in order from the front, it increases by the received data size and moves to the right. When a retransmitted packet is received in a state where there is a missing data portion (loss segment) that cannot be received and the loss segment disappears, a pointer left_recv (710) indicating the boundary between the aligned data and the unaligned data , 723) moves to the left end of the smallest loss segment. The proxy 900 sequentially reads data from the left_rbuf (709, 722) indicating the boundary between the read data and the unread data in the right direction, and moves the left_rbuf (709, 722) to the right by the read data size. The maximum data size that can be read is the difference between left_recv (710, 723) and left_rbuf (709, 722).
The transmission buffers 510 and 511 include a pointer right_sbuf (717, 730) indicating the head of data that has been written by the proxy 900 and can be transmitted, and a pointer right_send (716, indicating the head of data that has already been transmitted). 729) and a pointer left_send (715, 728) indicating the head of data for which an acknowledgment has been received from the receiving side.
The pointer right_sbuf (717, 730) indicating the head of data that has been written and can be transmitted by the proxy 900 increases by the written data size each time the proxy 900 writes data, and moves to the right. . New data is transmitted to the right starting from the pointer right_send (716, 729) indicating the head of the transmitted data, and the right_send (716, 729) increases by the transmitted data size and moves to the right. When an acknowledgment packet having a reception sequence number larger than left_send (715, 728) is received from the receiving side, left_send (715, 728) increases to the reception sequence number described in the acknowledgment packet and moves to the right. Moving.

FIG. 6 shows a format diagram of a packet transmitted and received by the apparatus. The packet includes a MAC header 600, an IP header 610, a TCP header 620, a TCP option header 630, and a payload 650. The MAC header 600 includes a DMAC 601 that represents a destination MAC address, an SMAC 602 that represents a source MAC address, and a Type 603 that represents a MAC frame type. The IP header 610 includes an IP length 611 representing the packet length excluding the MAC header, a protocol 612 representing the protocol number, a SIP 613 representing the transmission source IP address, and a DIP 614 representing the destination IP address. The TCP header 620 includes a src. port 621 and dst. a port 622; a SEQ 623 representing a transmission sequence number; an ACK 624 representing a reception sequence number; a flag 625 representing a TCP flag number; and a tcp hlen 626 representing a TCP header length. The TCP option header 630 includes an option kind 631 representing an option type, an option length 632 representing an option length, and left_edge_1 to 4 (633, 633, 633, 633, 633, 633, 633, and 633). 635, 637, 639), right_edge_1 to 4 (634, 636, 638, 640). In some cases, left_edge_1 to 4 (633, 635, 637, 639) and right_edge_1 to 4 (634, 636, 638, 640) are used to notify the positions of data portions that could not be received partially. Further, the TCP option header 630 may be used for information exchange between devices when starting TCP communication.
For example, the MSS (Maximum Segment Size) option is used to notify the opposite device of the MSS size that can be received by the own device when TCP communication is started. The SACK (Selective Acknowledgments) option is used not only to notify the opposite device that the device is compatible with the SACK option when starting TCP communication, but also when discarding is detected during communication. It is also used to notify the opposite device of the part that could be partially received. The time stamp option is used to notify the opposite device of the reception time of its own device during communication. As described above, the TCP option is used to transmit functions and information that can be supported by the own apparatus to the opposite apparatus at the start of communication and during communication.

FIG. 7 shows a format diagram of the status table 700.
The state table 700 of the apparatus 200 represents, for example, n entries 701 for recording the state of each TCP connection, connect_num 765 indicating the number of connections established for communication, and the number of connections that are actually transmitting data. active_snd_num 766, max_speed 767 that defines the upper limit bandwidth of the entire apparatus, and weight_sum 768 that represents the total weight of the traffic of each connection. TCP-way-handshake-completed communication is regarded as a connection in which communication is established. Further, a connection in which a certain amount of data is accumulated in the LAN-side reception buffer and the WAN-side transmission buffer, or a connection whose latest transmission band is a certain value or more is regarded as a connection that is actually transmitting data. A method for calculating the weight of the communication amount of each connection will be described later. The upper limit band may be determined for each opposing base (opposite device), and may have a different value for each of the plurality of opposing bases 1 to n as max_speed1 to n (767-1 to n). FIG. 18 shows an example of a state table 700-2 having upper limit bands max_speed1 to n (767-1 to n) for each opposing device. In this case, the upper limit band max_speed 767 of the opposite device corresponding to the corresponding connection is used for the calculations shown in FIGS.

Each entry 701 includes, for example, a VLD 702 that describes whether or not the entry is in use, a connect_state 703 that describes whether or not a LAN or WAN connection is being established, and the IP address of the terminal on the LAN side. LIP 704 representing, WIP 705 representing the IP address of the terminal on the WAN side, Lport 706 representing the TCP port number of the terminal on the LAN side, Wport 707 representing the TCP port number of the terminal on the WAN side, and the state of TCP communication on the LAN side Lan_state 708 representing a LAN side receive buffer management pointer, lan_left_rbuf 709, lan_left_recv 710, lan_right_recv 711 representing a LAN side window buffer option value, and lan_ representing a LAN side window scale option value s712, lan_rtt 713 representing the average RTT on the LAN side, lan_wan 714 representing the size of data being read from the reception buffer on the LAN side, lan_left_send 715, lan_right_send 716, lan_right7 and lan_right7, Lcwnd 718 representing the congestion window size on the LAN side, Lrwnd 719 representing the reception window size on the LAN side, Lmss 720 representing the size of the maximum segment size (MSS) on the LAN side, wan_state 721 representing the state of TCP communication on the WAN side, Wan_left_rbuf 722, wan_left_recv 723, and wan_ representing pointers for WAN side reception buffer management right_recv 724, wan_ws 725 representing the value of the window scale option on the WAN side, wan_rtt 726 representing the average / initial RTT on the WAN side, wan_lan 727 representing the data size being read from the reception buffer on the WAN side, and the WAN side Wan_left_send 728, wan_right_send 729, wan_right_sbuf 730 representing the transmission buffer management pointer, Wcwnd 731 representing the WAN-side congestion window size, Wrnd 732 representing the WAN-side reception window size, ss representing the maximum size of the WAN S, and ss 33 Send old_wan_left_send 734 indicating the location of the ACK received at the update time and the packet Control band token 738 for controlling the band to be transmitted, old_token 739 indicating the control band at the previous update time, old_old_token 740 indicating the control band at the previous update time, and the minimum band to be secured for transmitting the packet Min_token 741 that represents, t_token 742 that represents the most recent control band in which congestion has not been detected, c_token 743 that represents the control band at the time of the most recent periodic update, inc_time 744 that represents the most recent time at which the control band started to increase, Snd 745 representing the transmission band at the time, old_snd 746 representing the transmission band at the time of the previous update, old_old_snd 747 representing the transmission band at the last update time, and rt representing the retransmission band or the discard band at the current time 748, old_rts749 indicating the retransmission band or discard band at the previous update, rcv750 indicating the reception band at the current time, old_rcv751 indicating the reception band at the previous update, and the latest update time at which the control band was updated renewed_time 752, loss_ratio 753 representing the retransmission rate or discard rate at the current time, old_loss_ratio 754 representing the retransmission rate or discard rate at the previous update, old_renewed_time 755 representing the last update time when the control band was updated, and transmission at the current time Snd_byte 756 representing the byte integration value, rts_byte 757 representing the retransmission byte integration value at the current time, ack_byte 758 representing the reception byte integration value at the current time, and the rate of change of the discard rate Having a threshold K759 for detecting congestion, the threshold T760 for a period of time is to be linearly increased when congestion has not occurred, the traffic weight weight764 describing the communication bandwidth required by the.

FIG. 9 shows a block diagram of proxy 900.
The proxy 900 includes a data reading unit 901 that reads data from the reception buffer rubuf 500 on the LAN side, and a data processing unit 902 that processes the read data such as compression, decompression, encryption, decryption, deletion, duplication, and appending. A data writing unit 903 that writes processed data to the WAN-side transmission buffer sbuf511, a data reading unit 906 that reads data from the WAN-side reception buffer rbuf501, and compression / decompression / encryption / decryption of the read data A data processing unit 905 that performs processing such as deletion, duplication, and appending, and a data writing unit 904 that writes processed data to the transmission buffer sbuf 510 on the LAN side. Data may be exchanged between the data processing unit 902 and the data processing unit 905. The data processing may be other than the above example.
The data reading unit 901 estimates the data size to be read and the data size after data processing from the top data read from the aligned data accumulated between lan_left_rbuf 709 and lan_left_recv 710. As the top data, a TLS (Transport Layer Security) / SSL (Secure Socket Layer) header, an SMB (Server Message Block) header, or the like may be used. From the value described in the TLS / SSL header, the plaintext data size excluding the checksum and header after decryption can be estimated. From the SMB header, it is possible to estimate the command data size after creating a new command, prefetching an additional command, or the like. If the estimated processed data size is added to the difference between wan_right_sbuf 730 and wan_left_send 728, that is, the total value of untransmitted data and ACK confirmation waiting data, if the WAN transmission buffer size wan_sbuf_size is not exceeded, the data is read. And transferred to the data processing unit 902. Further, the larger one of the estimated data size to be read and the data size after data processing is described in lan_wan 714 of the state table 700.
Another data reading unit 906 estimates the data size to be read and the data size after data processing from the top data read from the aligned data accumulated from wan_left_rbuf 722 to wan_left_recv 723. As the top data, a TLS (Transport Layer Security) / SSL (Secure Socket Layer) header, an SMB (Server Message Block) header, or the like may be used. If the estimated processed data size is added to the difference between lan_right_sbuf 717 and lan_left_send 715, that is, the total value of untransmitted data and ACK confirmation wait data, if the transmission buffer size lan_sbuf_size on the LAN side does not exceed, the data is read. And transferred to the data processing unit 905. Furthermore, the larger one of the estimated data size to be read and the data size after data processing is described in wan_lan 727 of the state table 700.

FIG. 10 shows a block diagram of the TCP processing unit 1000 on the WAN side.
A TCP processing unit 1000 that realizes TCP communication includes an RX unit (reception unit) 1002 that performs reception processing and a TX unit (transmission unit) 1001 that performs transmission processing.
The RX unit 1002 is based on a packet distribution unit 1016 that separates a received packet into a TCP control packet with a flag such as SYN or FIN, a packet with data, and an ACK packet, and a flag number described in the TCP control packet. Based on the TCP control unit 1007 that changes the TCP state (lan_state 708, wan_state 721) in the state table 700, and the transmission sequence number SEQ623 and the reception sequence number ACK 624 of the received data packet, the buffer management pointer in the state table 700 is set. It has a reception history update unit 1006 that changes and sends back an ACK packet.
The TX unit 1001 changes the buffer management pointer in the state table 700 based on the TCP control unit 1003 that transmits the TCP control packet using the TCP state lan_state 708 and wan_state 721 in the state table 700, and the received ACK packet. Using the partial acknowledgments left_edge_1 to 4 (633, 635, 636, 639) and right_edge_1 to 4 (634, 636, 638, 640) described in the received ACK packet, data is read from the transmission buffer sbuf511 and the packet is retransmitted. In addition, a packet retransmission unit 1004 for notifying the transmission bandwidth control unit 1015 of the retransmission bit length and the number of received ACKs, and a packet carrying data read from the transmission buffer sbuf 511 are transmitted, and the status table 00, the buffer management pointer in 00 is changed, the transmission history update unit 1005 that notifies the transmission bandwidth control unit 1015 of the transmission bit length, the retransmission packet and the data packet are received, and the buffers 1 to n (1009-1 to n) are received. The allocating unit 1008, the timer 1013 that generates the current time and notifies the transmission band control unit 1015, and the interval time (predetermined fixed value or measured average RTT) are stored and the transmission band control unit 1015 is stored. The interval storage unit 1014 for notifying the token, the state table 700, the transmission bandwidth control unit 1015 for notifying the token update unit 1017 of the token size of each TCP connection, the token bucket for each TCP connection, and the transmission Talk to notify multiplexer 1012 of possible connections Having an updating unit 1017, ACK packet, TCP control packet, the retransmission packet, the aggregate data packet FIFO, and a multiplexer 1012 and a buffer 1009,1010,1011 outputs.

In this embodiment, among the blocks of the TX unit 1001, blocks that transmit data according to the control band (maximum transmission band) of each TCP communication (for example, the token update unit 1017, the multiplexer 1012, the buffer 1009, etc.) are transmitted together. Sometimes referred to as a control unit. FIG. 11 is a block diagram of the TCP processing unit 1100 on the LAN side.
A TCP processing unit 1100 that realizes TCP communication includes an RX unit (reception unit) 1102 that performs reception processing and a TX unit (transmission unit) 1101 that performs transmission processing.
An RX unit (reception unit) 1102 that performs reception processing includes a packet distribution unit 1108 that separates a received packet from the filter 202 into a TCP control packet, a data-added packet, and an ACK packet, and a status table based on the received TCP control packet Based on the TCP control unit 1107 that changes the TCP states lan_state 708 and wan_state 721 in the 700, and the transmission sequence number SEQ 623 and the reception sequence number ACK 624 of the received data packet, the buffer management pointer in the state table 700 is changed and the ACK packet is changed. And a reception history update unit 1106 for accumulating the data packet data in the reception buffer rubuf500.
A TX unit (transmission unit) 1101 that performs transmission processing uses a TCP control unit 1103 that transmits a TCP control packet by using the TCP state lan_state 708 and wan_state 721 in the state table 700, and in the state table 700 based on the received ACK packet. From the transmission buffer sbuf510 using the partial acknowledgments left_edge_1 to 4 (633, 635, 636, 639) and right_edge_1 to 4 (634, 636, 638, 640) described in the received ACK packet. A packet retransmission unit 1104 that reads data and retransmits the packet, and transmits a packet with the data read from the transmission buffer sbuf 510 to change the buffer management pointer in the state table 700 With a gravel updating section 1105, ACK packet, TCP control packet, the retransmission packet, the aggregate data packet in FIFO, the multiplexer 1113 and the buffer 1109 to 1112 output.
The transmission bandwidth control unit 1015 of the WAN-side TCP processing unit 1000 manages, in the state table 700, renewed_time 752 indicating the latest update time when the control bandwidth is updated and old_renewed_time 755 indicating the last update time when the control bandwidth is updated. is doing. When the difference between the latest update time renewed_time 752 and the current time of the timer 1013 becomes larger than the interval time of the interval storage unit 1014, the interval time is added to the latest update time renewed_time 752 to obtain a new latest update time renewed_time 752. . The most recent update time renewed_time 752 before the addition is old_renewed_time 755 representing the last update time. That is, the latest update time renewed_time 752 used immediately before the latest update time renewed_time 752 becomes old_renewed_time 755 representing the last update time. As the interval time, a measured average RTT or initial RTT (wan_rtt 519) may be used, or a fixed value may be used.

The flow of a packet in the apparatus 200 when a packet with data is received from the LAN side will be described with reference to FIG.
The packet with data arriving from the LAN side enters the LAN side TCP processing unit 1100 and arrives at the reception history update unit 1106. The reception history update unit 1106 returns the ACK packet to the LAN side via the aggregation unit 1113 and accumulates the data described in the packet in the LAN side reception buffer rbuf500. Further, the pointer of the status table 700 is updated based on the accumulated data size. The data reading unit 901 reads the aligned data stored in the LAN side reception buffer rubuf 500 and transfers it to the data processing unit 902. Further, the pointer of the state table 700 is updated based on the read data size. The data processing unit 902 processes the data and transfers it to the data writing unit 903. Furthermore, the data size being processed in the state table 700 is updated based on the data size being processed. The data writing unit 903 writes the processed data to the WAN side transmission buffer sbuf511. Further, the pointer of the state table 700 is updated based on the written data size. The data written in the WAN side transmission buffer sbuf 511 is read from the transmission history update unit 1005 of the WAN side TCP processing unit 1000 and transmitted to the WAN side as a packet with data.
The reception history update unit 1106 will be further described. The remaining amount of the reception buffer is calculated by subtracting the difference between lan_right_recv 711 and lan_left_rbuf 709 from the maximum value of the reception buffer on the LAN side. When the size of the payload 650 is equal to or smaller than the remaining amount of the reception buffer, all the data described in the payload 650 is stored in the reception buffer. When the size of the payload 650 is larger than the remaining amount of the reception buffer, only data having a size corresponding to the remaining amount of the reception buffer from the beginning of the payload 650 is stored in the reception buffer. When the stored data size is larger than 0, the reception buffer management pointer is updated based on the value of SEQ 623 described in the TCP header 620 of the packet with data and the stored data size. For example, when the value obtained by adding the stored data size to SEQ623 described in the packet header is larger than lan_right_recv711, lan_right_recv711 is changed to the value obtained by adding the stored data size to SEQ623. Further, the received data is described in the reception buffer on the LAN side so that the end of the received data is lan_right_recv711. Thereafter, an ACK packet in which one reception buffer management pointer lan_left_recv 710 is written in ACK 624 of the TCP header 620 is returned to the LAN side.
The transmission history update unit 1005 will be further described. Data from wan_right_send 729 to the maximum wan_right_sbuf 730 is read from the WAN side transmission buffer sbuf 511 in the right direction. wan_right_send 729 increases by the read data size and moves to the right. Further, the read data is described in the payload 650, and a packet with data to which the TCP header 620 in which wan_right_send 729 is described in SEQ623 is added is transmitted to the WAN side.

(Variable used to control the transmission bandwidth of data going to the WAN side)
The transmission bandwidth control unit 1015 controls the transmission bandwidth of data going out to the WAN side of each TCP communication using the variables managed by the state table 700.
The variables of the status table 700 managed by the transmission bandwidth control unit 1015 will be described. The state table 700 includes, for each connection, renewed_time 752 indicating the latest update time when the control band is updated, old_renewed_time 755 indicating the last update time when the control band is updated, and transmission byte integration from the latest update time renewed_time 752 to the current time. Value snd_byte 756 -retransmission byte integration value rts_byte 757 -reception byte integration value ack_byte 758 -control band token 738 -transmission band snd745 -reception band rcv750 -retransmission band or discard band rts748 -retransmission rate or loss rate loss_ratio753 Control band old_token7 until update time renewed_time 752 9. Transmission band old_snd 746 Reception band old_rcv751 Retransmission band or discard band old_rts749 Retransmission rate or discard rate old_loss_ratio 754, Last update time old_renewed_time 755 Previous control band old_old_token 740 Location old_wan_left_send 734, min_token 741 representing the minimum bandwidth reserved for transmitting the packet, t_token 742 representing the latest control bandwidth in which congestion is not detected, and c_token 743 representing the control bandwidth at the latest periodic update Indicates the most recent time when the control bandwidth started to increase. And inc_time744, a record.
A control band token 738 after the latest update time renewed_time 752 represents a control band at the current time (in this embodiment, it is expressed as token or token). The transmission band after the latest update time renewed_time 752 represents the transmission band at the current time (in this embodiment, represented as snd), and the transmission bit integrated value after the latest update time renewed_time 752 is the current time and the latest update time renewed_time 752. It is obtained by dividing by the difference of. The retransmission band after the latest update time renewed_time 752 represents the retransmission band at the current time (in this embodiment, expressed as rts), and the retransmission bit integration value after the latest update time renewed_time 752 is the current time and the latest update time renewed_time 752. It is obtained by dividing by the difference of. The reception band after the latest update time renewed_time 752 represents the reception band at the current time (in this embodiment, expressed as rcv), and is a value obtained by adding the WAN side MSS and 8 to the number of ACK receptions after the most recent update time renewed_time 752. Is divided by the difference between the current time current_time and the latest update time renewed_time 752. The control bandwidth / transmission bandwidth / reception bandwidth / retransmission bandwidth before the latest update time renewed_time 752 represents the average value of the control bandwidth / transmission bandwidth / reception bandwidth / retransmission bandwidth from the update time old_renewed_time 755 to the latest update time renewed_time 752 ( In this embodiment, it is expressed as old_token, old_snd, old_rcv, old_rts). The control band / transmission band of the previous update time old_renewed_time 755 represents the control band / transmission band immediately before the previous update time old_renewed_time 755 (in the present embodiment, it is represented as old_old_token, old_old_snd). The retransmission rate / discard rate old_loss_ratio before the latest update time renewed_time 752 is obtained by old_rts / old_old_snd or 1-old_rcv / old_old_snd. Further, the retransmission rate / discard rate loss_ratio at the current time after the latest update time renewed_time 752 is obtained by rts / old_snd or 1-rcv / old_snd. A fixed value may be used as the interval time, or wan_rtt 726 described in the state table 700 may be used.

FIG. 8 shows the relationship between the last update time old_renewed_time 755, the latest update time renewed_time 752, the current time, and the control band token, transmission band snd, reception band rcv, retransmission band rts, retransmission rate / discard rate loss_ratio before and after that. .
The difference between the latest update time renewed_time 752 and the previous update time old_renewed_time 755 is the interval time. The average values of the control band and the transmission band of the interval time before the update time old_renewed_time 755 two times before are expressed as old_old_token and old_old_snd (801). The average values of the control bandwidth, transmission bandwidth, reception bandwidth, retransmission bandwidth, retransmission rate / discard rate between the last update time old_renewed_time 755 and the latest update time renewed_time 752 are represented by old_token, old_snd, old_rcv, old_rts, old_loss_ratio 80 ). The average value of the control band / transmission band / reception band / retransmission band / retransmission rate / discard rate from the latest update time renewed_time 752 to the current time current_time is expressed as token, snd, rcv, rts, and loss_ratio (801).
The transmission bandwidth control unit 1015 calculates the discard rate / retransmission rate (loss_ratio753 and old_loss_ratio754) using the above-described values described in the state table 700. The discard rate / retransmission rate loss_ratio 753 of the current time current_time is calculated as rts / old_token, rts / old_snd, 1-rcv / old_token, or 1-rcv / old_snd. The discard rate / retransmission rate old_loss_ratio 754 at the latest update time is calculated by old_rts / old_old_token or old_rts / old_old_snd or 1-old_rcv / old_old_token or 1-old_rcv / old_old_snd. Further, based on the change in the discard rate / retransmission rate (the ratio of old_loss_ratio 754 and loss_ratio 753), the control band (token or token) is determined and transmitted to the token update unit 1017. Further, the state table 700 is updated. Details of the method of updating the control band (token or token) will be described later with reference to FIGS.
The token update unit 1017 manages the token bucket for each TCP connection based on the value of the control band (token or token) transmitted from the transmission band control unit 1015, and notifies the multiplexer 1012 of a connection that can be transmitted.

(Control band token update process)
Details of a method in which the transmission bandwidth control unit 1015 updates the control bandwidth (token or token) will be described using the explanatory diagram of FIG. 12 and the flowcharts of FIGS. 13 to 18.
FIG. 12 is a graph showing time transitions of the transmission band 1201, the discard rate 1202, and the discard rate change rate 1203 on the transmission side of a device performing communication using the original TCP. In this embodiment, an example in which communication using unique TCP is used as an example will be described. However, the present invention is not limited to the example described below, and an appropriate protocol modified based on TCP communication and TCP communication may be applied.
There are roughly three phases in increasing / decreasing the transmission bandwidth of communication using the original TCP. Phase 1 is a step of increasing the transmission band, Phase 2 is a step of decreasing the transmission band, and Phase 3 is a step of making the transmission band constant.
First, the transmission bandwidth increases in phase 1 (1204), and at some point exceeds the bottleneck bandwidth (1213). When the transmission bandwidth exceeds the bottleneck bandwidth, packet discarding occurs, but it takes RTT or more until the discard location is notified from the reception side to the transmission side (1215). Therefore, when the transmission band exceeds the bottleneck band, the increase in the discard rate appears after RTT (1214). The discard rate is obtained by dividing the most recent retransmission band by the transmission band before RTT. While the transmission band is smaller than the bottleneck band, only the stochastic discard due to contention with other traffic occurs, so the discard rate is almost constant (1210). When the transmission band exceeds the bottleneck band and RTT or more elapses, discard due to overuse (1211) is added in addition to stochastic discard, and the discard rate starts to increase (1212). When the discard rate starts to increase, the change rate of the discard rate increases rapidly from 1 and exceeds the threshold value k (1209).

In communication using unique TCP, as described above, when the rate of change of the discard rate increases rapidly and exceeds the threshold value k, it is determined that congestion has occurred in the network.
If it is determined that congestion has occurred in the network, a value obtained by subtracting the current retransmission bandwidth from the transmission bandwidth before RTT is set as a new transmission bandwidth (1218). The reason why the new transmission band is calculated using the transmission band before RTT is that the time when the transmission band exceeds the bottleneck band is more than RTT. Since the increase in the discard rate continues for a while (1212), the transmission band continues to decrease during that time. The step of reducing the transmission band is phase 2 (1205). When the transmission band decreases and becomes smaller than the bottleneck band, the discard rate starts to decrease (1219). When the change rate of the discard rate becomes smaller than 1 and falls below the threshold value k (1220), it is determined that congestion does not occur in the network.
Even after it is determined that the network is no longer congested, the discard packet retransmission process continues. If the number of data parts that have been confirmed to be received has not increased compared to before RTT, it is determined that retransmission processing of the discarded packet is continued, and the transmission band is made constant according to the number of received ACKs. The step of making the transmission band constant is phase 3 (1206).
If the number of data parts that have been confirmed to be received has increased compared to before RTT, it is determined that the retransmission processing of the discarded packet has been completed, and the transmission band is increased again (phase 1).
Initially, the transmission band is increased slowly, for example, linearly (1207). If no congestion is detected for a certain period T, then the transmission band is increased rapidly (eg, non-linearly) (1208). When increasing non-linearly, it may be increased exponentially, such as multiplying by α _E every RTT (1216). The period T during which the initial transmission band is increased slowly (for example, linearly) may be determined by the RTT and the token (token: control band), or may be proportional to the product of these (1221). . While the initial transmission band is slowly increased (for example, linearly), the transmission band may be increased linearly at a rate proportional to MSS / RTT for each RTT. The proportionality coefficient α _L when increasing linearly at a rate proportional to MSS / RTT for each RTT may be set to a value smaller than 1 (1217).

According to the transmission bandwidth control method described above, network congestion is not detected, and the transmission bandwidth of the TCP communication is linearly set for a certain period after the data portion whose reception has been confirmed is being updated. A communication device that increases the transmission band in a non-linear manner is realized. Furthermore, using the discard rate and the rate of change of the retransmission rate, a communication device that detects network congestion, and the past history of the transmission band, the retransmission band, and the number of received ACKs, the discard rate or the retransmission rate and their changes A communication apparatus that estimates the rate and a communication apparatus that reduces the transmission band using the past history of the transmission band, the retransmission band, and the number of received ACKs when congestion is detected are realized.
Increase the transmission bandwidth more slowly (for example, linearly) than normal TCP communication for a certain period after network congestion is not detected and the data location that has been confirmed to be received is being updated. Thus, even when competing with the normal TCP communication, it is possible to prevent the normal TCP communication from being compressed, and the normal TCP communication can easily secure the band. Also, after a certain period of time has passed, the transmission bandwidth is rapidly increased (for example, exponentially) so that when there is no competition with normal TCP communication, the transmission bandwidth reaches the bottleneck bandwidth and reaches the top speed. Time can be shortened. In addition, by detecting network congestion using the rate of change of discard rate and retransmission rate, it is possible to distinguish between discards that occur probabilistically by competing with other traffic and discards due to excessive use of bandwidth. The transmission bandwidth can be continuously increased until the transmission bandwidth reaches the bottleneck bandwidth and reaches the top speed without being affected by the probabilistic discard, and the line bandwidth can be used up. Furthermore, when it is determined that the band is discarded due to excessive use of the band, the band can be reduced according to the scale of congestion by reducing the band using the past transmission band and the current retransmission band.

FIGS. 13 to 17 are flowcharts for explaining details of a method by which the transmission bandwidth control unit 1015 updates the control bandwidth (token or token).
FIGS. 13 to 15 show details of bandwidth control in the unique TCP, and FIGS. 16 to 17 show details of a method for dividing the maximum bandwidth in accordance with the communication amount in communication using the unique TCP.
FIG. 13 shows a conceptual flowchart when the transmission band control unit 1015 updates the control band (token or token). In the original TCP, the transmission bandwidth control unit 1015 executes processing according to this flowchart, thereby realizing bandwidth control based on the retransmission rate, and can use up the line bandwidth without depending on the RTT and the discard rate. Each step in FIG. 13 is executed by the transmission band control unit 1015.
In the transmission band control unit 1015, when the control band update process starts (step 1301), it is determined whether or not the number of confirmed ACKs has increased for a certain period (step 1302). If the number of confirmed ACKs has increased for a certain period, it is determined that retransmission has failed, and the control band is made constant according to the number of received ACKs (step 1306). For example, the control band token 738 is set as the reception band rcv750. When the number of confirmed ACKs increases, the rate of increase of the packet retransmission rate (= value calculated by rts / old_token or rts / old_snd or 1-rcv / old_token or 1-rcv / old_snd) is determined in advance. It is determined whether or not the threshold value is exceeded (step 1303). When the increase rate of the packet retransmission rate exceeds a predetermined threshold, the current retransmission band (rts) and the past control band (old_token 739) or the past (before the reference time) The control band (token 738) is updated using the transmission band (old_snd 746) (step 1304). For example, the control band in the past (before the latest update time renewed_time 752) is reduced by an amount corresponding to the current retransmission band to obtain the control band at the current time. On the other hand, if the increase rate of the packet retransmission rate does not exceed a predetermined threshold in step 1303, the control band is increased (step 1305). After step 1304, step 1305, and step 1306, the control band (token 738) is updated based on the minimum band (min_token 741) of each connection (step 1307). Further, the control band token is updated based on the weight weight 764 of each connection (step 1308). A method for calculating the weight of each connection weight 764 will be described later. By changing the control band (token 738), the amount of tokens accumulated in the token bucket changes, and thereby the packet transmission rate can be changed.
By detecting the congestion of the network using the rate of change of the discard rate and retransmission rate, it is possible to distinguish between discard that occurs probabilistically by competing with other traffic and discard due to excessive use of bandwidth, The transmission bandwidth can be continuously increased until the transmission bandwidth reaches the bottleneck bandwidth and reaches the top speed without being affected by the probabilistic discard, and the line bandwidth can be used up. Furthermore, when it is determined that the band is discarded due to excessive use of the band, the band can be reduced according to the scale of congestion by reducing the band using the past transmission band and the current retransmission band.

FIG. 14 shows a detailed flowchart of step 1305 when the transmission bandwidth control unit 1015 increases the control bandwidth (token 738 or token).
It is determined whether or not the difference between the current time current_time and the inc_time 744 representing the most recent time at which the control bandwidth has started to be increased is less than the threshold T760 (step 1401). If it is less than the threshold value T760, the control band token 738 is slowly increased (step 1403). For example, the coefficient α _L is linearly increased as token = token + α _L × MSS × 8 / RTT. When the threshold value is T760 or more, the control band token is rapidly increased (step 1402). For example, the coefficient α _E is increased by an exponent such that token = α _E × token.
FIG. 15 shows a detailed flowchart when the transmission band control unit 1015 updates the control band (token 738 or token). FIG. 15 partially corresponds to the processing of FIG.
Each step is executed by the transmission band control unit 1015. In the original TCP, the transmission bandwidth control unit 1015 executes processing according to this flowchart, thereby realizing bandwidth control based on the retransmission rate, and can use up the line bandwidth without depending on the RTT and the discard rate.
When update processing of the control band (token) starts (step 1501), the transmission band control unit 1015 stores the difference between the current time current_time output from the timer 1013 and the latest update time renewed_time 752 described in the state table 700 as an interval storage. It is determined whether or not the interval time output by the unit 1014 is longer than the interval time (step 1502). As the interval time, wan_rtt 726 of the state table 700 in which the average value or initial value of the measured RTT is recorded may be used. If it is determined to be true in step 1502, the value of the current control band token after the latest update time renewed_time 752 is saved in tmp (step 1503). Further, it is determined whether or not the number of confirmed ACKs has increased in a certain period. Specifically, it is determined whether or not the ACK confirmed location wan_left_send is larger than the ACK confirmed location old_wan_left_send 734 at the latest update time renewed_time 752 (step 1504). If it has increased, it is determined whether the increase rate of the packet retransmission rate has exceeded a threshold value. Specifically, the retransmission band or discard band rts748 from the latest update time renewed_time 752 to the current time current_time stored in the state table 700, the transmission band old_snd 746 or the control band from the previous update time old_renewed_time 755 to the latest update time renewed_time 752 The discard rate loss_ratio 753 at the current time current_time obtained by dividing by the old_token 739 is the retransmission band from the last update time old_renewed_time 755 to the latest update time renewed_time 752 or the discard band old_rtw7_new_old5 ld_snd747 or K times the old retransmission ratio old_loss_ratio754 as of the most recent update time renewed_time752 obtained by dividing the control band Old_old_token740: determines greater or not than (K advance one or more coefficients determined) (Step 1505). If the increase rate of the packet retransmission rate exceeds the threshold value, it is determined that congestion has occurred in the network, and the control bandwidth token 738 is decreased (step 1506). This corresponds to phase 2 described with reference to FIG. Specifically, a value obtained by subtracting the retransmission band rts748 from the latest update time renewed_time 752 to the current time from the control band old_token 739 from the last update time old_renewed_time 755 to the latest update time renewed_time 752 is set as a new control band token 738. Further, t_token 742 representing the latest control band in which congestion is not detected is overwritten with the new control band token 738, and inc_time 744 representing the latest time when the control band is started to be increased is overwritten with the current time current_time.

If the increase rate of the packet retransmission rate does not exceed the threshold value in step 1505, it is determined that the network is not congested, and the control bandwidth token 738 is increased (step 1507). This corresponds to phase 1 described with reference to FIG. Specifically, the coefficient α _L is linearly increased as token = token + α _L × MSS × 8 / RTT, or the coefficient α _E is increased exponentially as token = α _E × token. If the number of confirmed ACKs does not increase in a certain period in step 1504, it is determined that retransmission of the packet is continuing, and the control band token 738 is kept constant according to the number of received ACKs (step 1508). This corresponds to the phase 3 described with reference to FIG. Specifically, the control band token 738 is the reception band rcv 750 from the latest update time renewed_time 752 to the current time current_time. Further, t_token 742 representing the latest control band in which congestion is not detected is overwritten with the new control band token 738, and inc_time 744 representing the latest time when the control band is started to be increased is overwritten with the current time current_time.
When the processing of steps 1506 to 1508 is completed, the value managed in the state table 700 is updated. For example, the transmission band old_old_snd 747 at the last update time old_renewed_time 755 = the transmission band old_snd 746 at the previous update time renewed_time 752, the transmission band old_snd 746 at the last update time renewed_time 752, the transmission band old_snd 746 at the current time current 7 Retransmission band rts748 at current time current_time, last update time old_renewed_time 755 = last update time renewed_time 752, last update time renewed_time 752 = previous update time renewed_time 752+ Interval interval, transmission byte integration value snd_byte 756 = 0, retransmission byte integration value rts_byte 757 = 0, reception byte integration value ack_byte 758 = 0, previous update time old_renewed_time 755 Control band old_token 739 = tmp, control band c_token 743 at the time of previous update = new control band token 748, and the like are recorded in the status table 700 (step 1509). Thereafter, the process proceeds to step 1512.

On the other hand, if it is determined to be false in step 1502, the pointer wan_left_send 728 indicating the end of the ACK confirmed data is increased from the pointer old_wan_left_send 734 indicating the end of the ACK confirmed data at the last update time renewed_time 752, and It is determined whether the packet discard rate and the rate of change of the retransmission rate (loss_ratio753 / old_loss_ratio754) exceed a predetermined threshold K759 (step 1510). The value of K may be fixed or may vary depending on the value of token. If it is determined to be true in step 1510, it is determined that the network is congested, and a new control band is set so as to be smaller than the value of the control band old_token 739 at the last update time renewed_time 752, as in step 1506. The value of token 738 is determined (step 1511). For example, the retransmission / discard bandwidth rts748 is used to reduce the bandwidth. For example, the new control band token 738 = the control band old_token 739 at the previous update time renewed_time 752—the retransmission band or the discard band rts748, etc. (step 1511). If it is determined to be false in step 1510, nothing is done. By these steps, even if the interval time does not elapse, network congestion can be immediately detected from the increase in the retransmission rate, and the control bandwidth can be reduced. After these steps, move to step 1512.
In step 1512, when the control band token 738 is smaller than the minimum guaranteed band min_token 741 of each TCP communication, the control band token 738 is changed to the minimum guaranteed band min_token 741 of each TCP communication (step 1512). That is, the smaller of the tokens determined by the two expressions shown in step 1512 of FIG. Note that data such as token 738 and min_token 741 in step 1512 can be read with reference to the state table 700. After this step, the process proceeds to step 1513.
In step 1513, when the control bandwidth token 738 is larger than the maximum bandwidth max_token 770 determined by the traffic weight weight 764 of each TCP communication, the control bandwidth token 738 is changed to the maximum bandwidth max_token 770 (step 1513). The maximum bandwidth max_token 770 determined by the traffic weight weight 764 is determined by a flowchart described later.

By changing the control bandwidth token 738 based on the flowchart shown in FIG. 15, the amount of tokens accumulated in the token bucket changes, and thereby the packet transmission rate can be changed. Furthermore, by performing bandwidth control based on the discard rate or retransmission rate, the transmission bandwidth reaches the bottleneck bandwidth and reaches the top speed without being affected by the discard that occurs stochastically due to competition with bursty traffic. Until then, the transmission band can be increased. Thereby, the original TCP can use up the line bandwidth without depending on the RTT and the discard rate.
FIG. 16 shows a flowchart for the transmission bandwidth control unit 1015 to calculate the traffic weight weight 764 of each TCP communication. This flowchart is executed at an appropriate timing before step S1513 in FIG. For example, it may be executed every interval or may be executed at other appropriate timing.
When the update processing of the traffic weight (weight 764) is started (step 1600), the transmission bandwidth control unit 1015 is the bit amount of data accumulated in the reception buffer on the LAN side and the transmission buffer on the WAN side (wan_right_sbuf730-wan_left_send728 + lan_right1-rec71). The value obtained by dividing lan_left_rbuf709) × 8 by WAN_rtt726, which is the RTT on the WAN side, is assigned to weight 764 (step 1601). This is based on the idea that a value that can completely send data staying in the apparatus 200 in 1 RTT is regarded as a necessary band. Next, the transmission bandwidth control unit 1015 determines whether or not the traffic weight weight 764 is greater than the value obtained by dividing max_speed 767, which is the maximum bandwidth of the device 200, by active_snd_num 766 representing the number of connections that are actually transmitting data. (Step 1602). Note that the amount of bytes of data accumulated in the LAN side reception buffer and the WAN side transmission buffer (wan_right_sbuf730-wan_left_send728 + lan_right_recv711-lan_left_rbuf709) is a value greater than or equal to a certain value, or the current bandwidth current_dn45 is a value equal to or greater than the current value current_n7. It is regarded as a connection that is actually transmitting data. If it is determined to be true in step 1602, the transmission bandwidth control unit 1015 substitutes a value obtained by equally dividing the maximum bandwidth max_speed 767 of the device by the number of connections active_snd_num 766 during data transmission into the traffic weight weight 764 (step 1603).
By limiting the traffic weight weight 764 to a bandwidth equal to or less than the bandwidth when fair distribution is performed using the above flowchart, it is possible to prevent a communication with a large traffic from using too much bandwidth.

FIG. 17 shows a flowchart for the transmission bandwidth control unit 1015 to calculate the maximum bandwidth max_token 770 of each TCP communication using the traffic weight weight 764.
When update processing of the maximum bandwidth (max_token 770) of each TCP communication is started (step 1700), a value obtained by equally dividing the maximum bandwidth max_speed 767 of the apparatus 200 by the number of connections active_snd_num 766 during data transmission is the sum Σweight (weight 68) of the traffic weight weight 764. The value obtained by multiplying the value divided by the maximum bandwidth max_speed 767 of the device 200 is substituted into the maximum bandwidth max_token 770 of each TCP communication (step 1701). This means that, of the total sum Σweight of the traffic weight weight 764, the maximum possible value of the traffic weight weight 764 is assigned as the maximum value of each communication. If the total sum Σweight of the traffic weight weight 764 is smaller than the value obtained by equally dividing the maximum bandwidth max_speed 767 of the device 200 by the number of connections active_snd_num 766 during data transmission (step 1702), the maximum bandwidth of the device 200 is limited to communication with a small traffic. Assuming that max_speed 767 cannot be used up, the maximum bandwidth max_token 770 of each TCP communication is set as the maximum bandwidth max_speed 767 of the apparatus 200 (step 1703).
In FIG. 4, by changing the control band token 738 according to the flowcharts of FIGS. 15 to 17, the maximum bandwidth max_speed 767 of the apparatus 200 when one communication with a small communication amount and two communication with a large communication amount are performed simultaneously. Shows how is divided.
The communication 401 with a small communication amount can use a necessary band without compressing the band with the two communications 402 and 403 with a large communication amount. On the other hand, the two communications 402 and 403 having a large communication volume can be used up while equally dividing the remaining band of the communication 401 having a small communication volume.
Note that the apparatus 200 uses the values such as token 738 and snd 745 in the state table 700 to transmit the time transition of the throughput for each communication as illustrated in FIG. 4 to the external terminal 240 via the interface 230. It may be displayed.
As described above, according to the flowcharts of FIGS. 15 to 17, the maximum bandwidth max_token 770 for each TCP communication is determined using the traffic weight weight 764, and the control bandwidth token 738 is limited to the maximum bandwidth max_token 770 for each TCP communication. While protecting a communication band with a small amount of communication, it is possible to use up a band where a communication with a large amount of communication is left evenly divided.

In the above example, calculation is performed using RTT (round trip delay time), but other communication delay time may be used.
Here, a supplementary description will be given of the fact that by limiting the upper limit of the control band, communication with a large amount of communication can use an excess band as shown in FIG. In phase 1 described with reference to FIGS. 12 and 14, the control bandwidth (token) increases even in communication (connection) with a small communication amount (FIGS. 12: 1204, 1207, 1208; FIG. 15: 1507). The upper limit of this control band is limited in step S1513 in FIG. If FIG. 16 and FIG. 17 are omitted, the maximum bandwidth may be divided by the number of connections, and the state shown in FIG. 3 may be obtained.
In the present embodiment, if there is another communication (connection) with a large amount of traffic, the traffic weight weight increases, so that the maximum control bandwidth max_token of each connection becomes smaller than the conventional one. Therefore, the upper limit of the control band for communication with a small communication volume is limited as compared with the conventional one, and the transmission band is limited. The max_token becomes smaller as the amount of buffer stored data for communication with a larger amount of communication becomes larger, and the max_token becomes smaller as the RTT becomes smaller.
Therefore, while the minimum bandwidth for communication with a small amount of communication is secured in step 1512, the maximum control bandwidth for communication with a small amount of communication is limited as the amount of data stored in the buffer for communication with a large amount of communication increases or the RTT decreases. As a result, communication with a large amount of communication can use the bandwidth.

(Configuration example)
One form of communication device manages the bandwidth related to packets transmitted from the first communication device to the second communication device via the network for each interval, and is based on the number of connections whose interval transmission bandwidth is equal to or greater than a certain value. Limit the upper bandwidth limit of each connection.
Another form of the communication device includes a buffer for storing packets transmitted from the first communication device to the second communication device via the network for each connection, and the data size of the packets stored in the buffer is a constant value. The upper limit bandwidth of each connection is limited based on the number of connections described above.
In each of the communication devices described above, the maximum bandwidth of a packet transmitted from the device may be determined, and the upper limit bandwidth of each connection may be limited based on a value obtained by dividing the maximum bandwidth by the number of connections.
In each communication device described above, the upper limit bandwidth of each connection may be limited based on a value obtained by dividing the maximum bandwidth determined for each opposing device by the number of connections.
In the communication apparatus described above, the round trip delay time may be measured for each connection, and the upper limit bandwidth of each connection may be limited based on a value obtained by dividing the buffer accumulation amount of each connection by the round trip delay time.
In the above communication device, even if the upper limit bandwidth of each connection is limited based on the larger value of the value obtained by dividing the maximum bandwidth by the number of connections and the value obtained by dividing the buffer accumulation amount of each connection by the round-trip delay time. Good.
In the communication apparatus described above, the transmission bandwidth of each connection may be controlled based on the discard rate measured for each connection and the change thereof.
In the communication apparatus described above, the transmission band of each connection may be controlled based on the control band of the past interval measured for each connection and the retransmission band / discard band of the latest interval.

According to one aspect of this embodiment,
A communication device that relays a plurality of TCP communications on the LAN side and the WAN side,
A bandwidth control unit for controlling the transmission bandwidth of each TCP communication;
A reception buffer for storing data received from the LAN side of each TCP communication;
A transmission buffer for storing data to be transmitted to the WAN side of each TCP communication;
A status table that records a history of data locations that have been confirmed to be received in each TCP communication;
A bandwidth table for recording past history of transmission bandwidth, control bandwidth, reception bandwidth, and retransmission bandwidth in each TCP communication;
Have
The bandwidth controller
Based on the past history of the transmission band, control band, reception band, and retransmission band described in the status table, and the history of the data location that has been confirmed to be received in the status table, the presence or absence of TCP communication congestion has been confirmed. It is determined whether or not the data part is being updated. When congestion is not detected and the data part that has been confirmed to be received is being updated, the TCP communication transmission band is increased. When congestion is detected, TCP communication is performed. Reduce the transmission bandwidth of
The round trip delay time indicates the number of connections where the amount of data accumulated in the transmission buffer and reception buffer exceeds a certain value, or the number of connections where the past transmission bandwidth exceeds a certain value, and the amount of data accumulated in the transmission buffer and reception buffer. A communication device is provided that limits the upper limit bandwidth of each connection based on the divided value.

The present invention can be used for a communication device that relays communication between terminals, for example.

200 Communication device 110, 120, 130 Network 111, 121, 131 Terminal 191, 192, 193 Line 1000, 1100 Processing unit 1015 Transmission bandwidth control unit 500, 501 Reception buffer 510, 511 Transmission buffer 900 Proxy 700 Status tables 502, 503, 504 Pointer 600 Header data 701 entry

Claims (15)

1. A buffer for storing packets transmitted from the first device to the second device via the network for each connection;
   A bandwidth control unit that controls the transmission bandwidth of each connection according to the control bandwidth of each connection to be set,
   The bandwidth control unit is a communication device that limits the upper limit of the control bandwidth for each connection based on an accumulation amount of packets of each connection accumulated in the buffer and a communication delay time of each connection.
2. The communication device according to claim 1.
   A communication device that limits the upper limit of the control band for each connection based on a value obtained by dividing the accumulated amount of packets accumulated in the buffer by a communication delay time.
3. The communication device according to claim 1.
   A state table for storing data portions for which reception confirmation for the transmitted packet has been received;
   The bandwidth control unit
   When congestion is not detected in a predetermined connection, and the data portion of the status table that has been confirmed to be received is updated within a predetermined time, the transmission bandwidth of the connection is increased,
   A communication device that reduces the transmission bandwidth of the connection when congestion is detected.
4. The communication device according to claim 3.
   The bandwidth control unit
   The predetermined maximum bandwidth and the number of connections whose amount of data stored in the buffer is equal to or greater than a predetermined threshold, or the number of connections whose past transmission bandwidth is equal to or greater than a predetermined threshold, and the buffer A communication device that limits the upper limit of the control bandwidth based on a value obtained by dividing the accumulated amount of accumulated packets by a communication delay time.
5. The communication device according to claim 3.
   Based on the accumulated amount of packets of each connection accumulated in the buffer and the communication delay time of each connection, the upper limit of the control bandwidth is set to a predetermined maximum for a connection having at least a smaller amount of communication than other connections. A communication apparatus that limits a transmission band by making a band smaller than a value obtained by dividing a band by the number of connections, and allows other connections to use a band larger than a value obtained by dividing a predetermined maximum band by the number of connections.
6. The communication device according to claim 4.
   Based on the value obtained by dividing the maximum bandwidth by the number of connections when the value obtained by dividing the amount of packets accumulated in the buffer by the communication delay time is greater than the value obtained by dividing the maximum bandwidth by the number of connections. A communication device for limiting the upper limit of the control bandwidth.
7. The communication device according to claim 1.
   For each interval, a past transmission band related to a packet transmitted from the first apparatus to the second apparatus via the network is managed, and the number of connections whose interval transmission band is equal to or greater than a predetermined threshold; and A communication device that limits the upper limit of the control bandwidth of each connection based on a value obtained by dividing the accumulated amount of packets accumulated in a buffer by a communication delay time.
8. The communication device according to claim 1.
   Based on the number of connections in which the amount of data accumulated in the buffer is equal to or greater than a predetermined threshold and the value obtained by dividing the accumulated amount of packets accumulated in the buffer by the communication delay time, the control bandwidth of each connection A communication device that limits the upper limit.
9. The communication device according to claim 1.
   The maximum bandwidth is determined for each opposing device, and for the connection corresponding to the opposing device, the control bandwidth of each connection corresponding to the opposing device is determined based on the value obtained by dividing the maximum bandwidth for the opposing device by the number of connections. A communication device that limits the upper limit.
10. The communication device according to claim 1.
    A communication apparatus for controlling a transmission band of each connection based on a discard rate measured for each connection and a change thereof by the band control unit.
11. The communication device according to claim 1.
    A communication apparatus in which the bandwidth control unit controls the transmission bandwidth of each connection based on a control bandwidth of a past interval measured for each connection, and a retransmission bandwidth and a discard bandwidth of the latest interval.
12. Storing packets transmitted from the first device over the network to the second device for each connection;
    The step of controlling the transmission bandwidth of each connection according to the set control bandwidth of each connection, and for each connection, based on the accumulated amount of packets of each connection accumulated in the buffer and the communication delay time of each connection And determining an upper limit value of the control band.
13. A buffer for storing packets transmitted from the first device to the second device via the network for each connection;
    With a bandwidth controller,
    The bandwidth control unit
    Limit the upper limit bandwidth of each connection based on the number of connections in which the data size of the packet stored in the buffer is equal to or greater than a predetermined threshold, or
    The transmission bandwidth related to packets transmitted from the first device to the second device via the network is managed for each predetermined interval, and the transmission bandwidth of the interval is based on the number of connections equal to or greater than a predetermined threshold. A communication device that limits the upper limit bandwidth of each connection.
14. The communication device according to claim 13.
    A communication device that limits a maximum bandwidth of each connection based on a value obtained by dividing a maximum bandwidth of a packet transmitted from the communication device in advance and dividing the maximum bandwidth by the number of connections.
15. The communication device of claim 14,
    The maximum bandwidth of the packet transmitted from the communication device is determined for each opposing device, and the upper limit of each connection is based on the value obtained by dividing the maximum bandwidth with the opposing device corresponding to the connection by the number of connections with the opposing device. A communication device that limits the bandwidth.

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