JP5087595B2 - Edge node, window size control method and program - Google Patents

Description

  The present invention relates to an edge node for controlling a window size used for transmission / reception of packet data, a window size control method, and a program.

  Communication between terminals such as personal computers is performed via a computer network such as the Internet. Data such as a file is transferred by this communication. In this type of data transfer system, TCP (Transmission Control Protocol), which is a standard transport protocol, is often used as a transport layer protocol.

  In data transfer, it may be required to transfer a large amount of data at high speed. In contrast, studies have been made to improve throughput by controlling the TCP window size to be constant (see, for example, Non-Patent Document 1).

“Examination of TCP flow rate control method in edge router”, IEICE General Conference, March 2007

  In TCP, bandwidth control that autonomously changes the window size according to packet discard is performed. That is, there is a feature that the window size is continuously increased unless packet discard occurs. Therefore, in TCP communication in a bandwidth guarantee network that restricts inflow at the entrance of the network in order to prevent traffic exceeding the guaranteed bandwidth from flowing into the network, the network is used to transmit data at a rate that exceeds the guaranteed bandwidth. Packet discard due to inflow restriction occurs at the entrance of the network, and the congestion control of TCP works, so that the throughput becomes sawtooth and the guaranteed bandwidth cannot be fully utilized.

  As a countermeasure against this problem, a technique for transmitting data at a constant throughput in accordance with a band guaranteed by changing the TCP protocol described above and a technique for controlling the advertisement window size to be constant are considered.

  On the other hand, the technique for controlling the advertisement window size to a constant does not take into account the queuing delay in the network device through which it passes and the fluctuation of the delay time due to the delay ACK algorithm in the receiving terminal. Therefore, if you continue to control with the window size calculated based on the propagation delay time measured at the start of communication, if the propagation delay time fluctuates, the band delay product is too small for the calculated window size and the guaranteed bandwidth There is a problem that cannot be fully utilized.

  An object of the present invention is an edge capable of efficiently using a guaranteed bandwidth and maintaining a high throughput even in the case where a variation in delay time due to a queuing delay or a delayed ACK algorithm occurs in data transfer in a bandwidth guaranteed network To provide a node, a window size control method, and a program.

The edge node of the present invention is:
An edge node connected between the data transmission terminal and the data reception terminal, connected to a bandwidth guarantee network in which a communication band between the data transmission terminal and the data reception terminal is guaranteed,
A bandwidth information holding unit for holding a guaranteed bandwidth, which is the guaranteed communication bandwidth, for each service target flow;
An ACK (Acknowledgement) packet token bucket and an RTT (Round Trip Time) measurement token bucket for each service target flow, and measure the throughput of data transmitted from the data transmission terminal to the data reception terminal; The token amount in the token bucket for the ACK packet is updated based on the throughput, and when the updated token amount exceeds the size of the token bucket for the ACK packet, the token amount exceeds the size of the token bucket for the ACK packet If the token amount for the RTT measurement token bucket is added to the RTT measurement token bucket and the token amount in the RTT measurement token bucket is equal to or greater than a preset threshold, the window size is a request for calculating the window size. After outputting the output request, and ACK token management unit for setting the amount of tokens in the RTT measurement token bucket to zero,
When the ACK token management unit outputs the window size calculation request , the guaranteed bandwidth, the token amount before being set to zero in the RTT measurement token bucket, the data transmitting terminal, and the data receiving terminal A window size calculation unit that calculates a window size based on the propagation delay time between
An advertising window size writing unit that rewrites the window size indicated in the ACK packet transmitted from the data receiving terminal to the data transmitting terminal in the service target flow with the window size calculated by the window size calculating unit.

In addition, when the data packet transmitted from the data receiving terminal is identified as the ACK packet, and the data packet is identified as the ACK packet, the ACK number indicated in the ACK packet is notified. Has a flow identification / distribution unit
The ACK token management unit transmits the ACK number notified from the flow identification / distribution unit, the ACK number indicated by the ACK packet recently transferred to the data transmission terminal, and the ACK packet recently transferred to the data transmission terminal. The throughput is calculated based on the time from the time until the notification and the guaranteed bandwidth.

  The window size calculation unit may calculate the propagation delay time using a 3 way-handshake packet.

Further, the window size control method of the present invention includes:
A window size control method in an edge node that is connected to a bandwidth guarantee network in which a communication band between a data transmission terminal and a data reception terminal is guaranteed, and is provided between the data transmission terminal and the data reception terminal. ,
A process of holding a guaranteed bandwidth, which is the guaranteed communication bandwidth, for each service target flow;
A process for measuring the throughput of data transmitted from the data transmitting terminal to the data receiving terminal;
A process of updating the token amount in the token bucket for ACK (Acknowledgement) packets provided for each of the service target flows based on the throughput;
When the updated token amount exceeds the size of the token bucket for the ACK packet, the amount of tokens exceeding the size of the token bucket for the ACK packet is set to RTT (Round Trip) provided for each service target flow. (Time) processing to add to the token bucket for measurement,
When the token amount in the RTT measurement token bucket is equal to or greater than a preset threshold value , the guaranteed bandwidth, the token amount in the RTT measurement token bucket, and between the data transmitting terminal and the data receiving terminal Processing for calculating the window size based on the propagation delay time in
After calculating the window size, a process of setting the token amount in the RTT measurement token bucket to zero;
And rewriting the window size indicated in the ACK packet transmitted from the data receiving terminal to the data transmitting terminal in the service target flow to the calculated window size.

A process of identifying whether the data packet transmitted from the data receiving terminal is an ACK packet;
When the data packet is identified as an ACK packet, the ACK number indicated by the ACK packet, the ACK number indicated by the ACK packet recently transferred to the data transmission terminal, and the ACK packet recently transferred to the data transmission terminal are transmitted. And a process of calculating the throughput based on the time from the determination to the identification and the guaranteed bandwidth.

  Further, the method has a process of calculating the propagation delay time using a 3-way-handshake packet.

The program of the present invention is
An edge node provided between the data transmitting terminal and the data receiving terminal is connected to a bandwidth guaranteed network in which a communication band between the data transmitting terminal and the data receiving terminal is guaranteed,
A procedure for maintaining a guaranteed bandwidth, which is the guaranteed communication bandwidth, for each service target flow;
A procedure for measuring the throughput of data transmitted from the data transmitting terminal to the data receiving terminal;
Updating the token amount in the token bucket for an ACK (Acknowledgement) packet provided for each service target flow based on the throughput;
When the updated token amount exceeds the size of the token bucket for the ACK packet, the amount of tokens exceeding the size of the token bucket for the ACK packet is set to RTT (Round Trip) provided for each service target flow. Time) to add to the token bucket for measurement,
When the token amount in the RTT measurement token bucket is equal to or greater than a preset threshold value , the guaranteed bandwidth, the token amount in the RTT measurement token bucket, and between the data transmitting terminal and the data receiving terminal A procedure for calculating the window size based on the propagation delay time in FIG.
After calculating the window size, a procedure for setting the token amount in the token bucket for RTT measurement to zero,
And a step of rewriting the window size indicated in the ACK packet transmitted from the data receiving terminal to the data transmitting terminal in the service target flow to the calculated window size.

A procedure for identifying whether the data packet transmitted from the data receiving terminal is an ACK packet;
When the data packet is identified as an ACK packet, the ACK number indicated by the ACK packet, the ACK number indicated by the ACK packet recently transferred to the data transmission terminal, and the ACK packet recently transferred to the data transmission terminal are transmitted. Then, the procedure for calculating the throughput is executed based on the time until the identification and the guaranteed bandwidth.

  Further, a procedure for calculating the propagation delay time using a 3-way-handshake packet is executed.

As described above, in the present invention, the token amount in the token bucket for the ACK packet is updated based on the throughput measured between the data transmitting terminal and the data receiving terminal, and the updated token amount is used for the ACK packet. When the token bucket size is exceeded and added to the RTT measurement token bucket, and the token amount in the RTT measurement token bucket is equal to or greater than the threshold, the guaranteed bandwidth, which is the communication bandwidth guaranteed by the network, and the RTT The window size of the ACK packet transmitted from the data receiving terminal to the data transmitting terminal is calculated based on the token amount in the measurement token bucket and the propagation delay time between the data transmitting terminal and the data receiving terminal. Since the size is rewritten to the calculated window size, the key In response to fluctuations in delay time due to delay delay and delay ACK algorithm at the data receiving terminal, the throughput can be controlled stably within the guaranteed bandwidth even when the rate control flow is highly multiplexed, so the guaranteed bandwidth can be used efficiently It becomes.

It is a figure which shows one Embodiment of the communication system provided with the edge node of this invention. It is a block diagram which shows the internal structure of the edge node shown in FIG. It is a figure for demonstrating packet distribution by the flow identification and distribution part shown in FIG. It is a sequence diagram for demonstrating the process until a window size is calculated among the window size control methods in this form. It is a sequence diagram for demonstrating the process after calculating a window size until writing the said window size among the window size control methods in this form. It is an image figure which shows the mode of the update of the ACK token bucket prepared for every control object TCP flow in the ACK token management part shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing an embodiment of a communication system provided with an edge node according to the present invention.

  As shown in FIG. 1, this embodiment includes edge nodes 11 and 12, a bandwidth management server 13, a data transmission terminal 14, and a data reception terminal 15.

  The data transmission terminal 14 is a communication terminal that is connected to the edge node 11 and transmits packet data to the bandwidth guarantee network 16 via the edge node 11.

  The data receiving terminal 15 is a communication terminal that is connected to the edge node 12 and receives packet data transmitted from the bandwidth guarantee network 16 via the edge node 12.

  The bandwidth management server 13 is a device that centrally manages bandwidth information of all links of the bandwidth guarantee network 16. The bandwidth information includes information on the guaranteed bandwidth allocated to the link. The bandwidth management server 13 notifies the edge nodes 11 and 12 of bandwidth information of each link being managed. As a result of bandwidth management by the bandwidth management server 13, a guaranteed bandwidth in the bandwidth guaranteed network 16 is secured for the link from the data transmitting terminal 14 to the data receiving terminal 15. As a result, as long as the data transmission terminal 14 transmits data below the guaranteed bandwidth, packet discard does not occur in the bandwidth guaranteed network 16.

The edge nodes 11 and 12 are connected to a bandwidth guarantee network 16 that is a communication network in which a communication bandwidth is guaranteed, and realizes communication between the data transmission terminal 14 and the data reception terminal 15 via the bandwidth guarantee network 16. ing. In addition, when communication using TCP is performed between the data transmission terminal 14 and the data reception terminal 15, the edge nodes 11 and 12 perform policing control using a token bucket method and control the window size.

  Here, the window size will be described.

  In general TCP (Transmission Control Protocol), two windows, an advertisement window and a congestion window, are defined as windows indicating the size of data that can be transmitted without waiting for arrival confirmation. The size of the advertisement window is determined on the data receiving side depending on the state of the reception buffer. On the other hand, the size of the congestion window is determined on the data transmission side according to the state of packet discard. As the window size used for flow control, the smaller one of the advertisement window size and the congestion window size is selected. This window size is updated when an ACK (Acknowledgement) packet (hereinafter referred to as ACK) that is a response packet to the data packet arrives.

  FIG. 2 is a block diagram showing an internal configuration of the edge node 11 shown in FIG. The edge node 12 shown in FIG. 1 has the same configuration.

  As shown in FIG. 2, the edge node 11 shown in FIG. 1 includes a data reception unit 21, a flow identification / distribution unit 22, an advertisement window size writing unit 23, a data transmission unit 24, and a band information holding unit 25. And a window size calculation unit 26 and an ACK token management unit 27.

  The data reception unit 21 receives a packet such as a data packet or an ACK packet, and outputs the received packet to the flow identification / distribution unit 22.

  The bandwidth information holding unit 25 holds the bandwidth information of the service target user notified from the bandwidth management server 13 and user information (destination / source IP (Internet Protocol) address, destination / source port number) in association with each other. . The bandwidth information includes information on the guaranteed bandwidth allocated to the link.

  The flow identification / distribution unit 22 guarantees a flow (service target flow) that is a target of a data transfer service that guarantees a band, based on user information that is held in the band information holding unit 25 together with the band information. The flow that is not the target of the data transfer service (service non-target flow) is identified. Furthermore, the flow identification / distribution unit 22 outputs the ACK packet of the service target flow to the advertisement window writing unit 23. Further, the flow identification / distribution unit 22 outputs the packet of the service asymmetric flow and the data packet of the service target flow to the data transmission unit 24. The flow identification / distribution unit 22 reads the ACK number from the ACK packet of the service target flow, notifies the ACK token management unit 27 of the read ACK number, and uses it for bandwidth control of the service target flow.

  The advertisement window writing unit 23 writes the value of the window size calculated by the window size calculation unit 26 in the window field indicating the window size of the ACK packet transmitted from the data receiving terminal 15 to the data transmitting terminal 14. The advertisement window writing unit 23 outputs the ACK packet in which the window size value is written to the data transmission unit 24.

  The data transmission unit 24 transmits the packet output from the flow identification / distribution unit 22 to the edge node 12 via the bandwidth guarantee network 16. In addition, the data transmission unit 24 transmits the ACK packet output from the advertisement window writing unit 23 to the edge node 12 via the bandwidth guarantee network 16.

  The window size calculation unit 26 uses the data throughput between the data transmission terminal 14 and the data reception terminal 15 measured by the ACK token management unit 27 and the guaranteed bandwidth of the band information held in the band information holding unit 25. Thus, the window size is calculated so that the data transmission bandwidth is within the guaranteed bandwidth.

  The ACK token management unit 27 adds a token at an arbitrary timing so that the service target flow does not transmit data at a rate equal to or higher than the guaranteed bandwidth. The ACK token management unit 27 also transmits the ACK number of the service target flow when the ACK packet of the service target flow passes through the flow identification / distribution unit 22 and the ACK number notified from the flow identification / distribution unit 22 to the data transmission terminal 14. Based on the difference from the ACK number of the latest ACK packet, the throughput between the data transmission terminal 14 and the data reception terminal 15 is measured. In addition, the ACK token management unit 27 notifies the measured throughput to the window size calculation unit 26.

  FIG. 3 is a diagram for explaining packet distribution by the flow identification / distribution unit 22 shown in FIG. Hereinafter, packet distribution by the flow identification / distribution unit 22 will be described in detail with reference to FIG.

  When a connection is established between the data transmission terminal 14 and the data reception terminal 15, data transfer is started. When the flow identification / distribution unit 22 of the edge node 11 receives the ACK packet from the data receiving terminal 15, the flow identification / distribution unit 22 determines whether the ACK packet is an ACK packet of the service target flow. When it is determined that the packet is an ACK packet of the service target flow, the flow identification / distribution unit 22 outputs the ACK packet to the advertisement window writing unit 23. When it is determined that the packet is a service non-subscription user packet or a data packet, the flow identification / distribution unit 22 outputs the service non-subscription user packet or data packet to the data transmission unit 24.

  The window size control method in this embodiment will be described below.

  FIG. 4 is a sequence diagram for explaining processing until the window size is calculated in the window size control method according to this embodiment.

  When the ACK packet transmitted from the data receiving terminal 15 to be serviced arrives at the flow identification / distribution unit 22 of the edge node 11 (step 201), the flow identification / distribution unit 22 uses the ACK token management unit 27 as an ACK number notification. Is notified of the user information of the service target flow and the ACK number of the ACK packet (step 202).

  Then, the ACK packet is output (transferred) from the flow identification / distribution unit 22 to the advertisement window writing unit 23 (step 203).

  Upon receiving the ACK number notification, the ACK token management unit 27 determines the difference between the ACK number notified in step 202 and the ACK number of the latest ACK packet that has already been transferred to the data transmission terminal 14 (hereinafter referred to as DiffACK). (Refer to step 204). Then, a data size corresponding to the calculated DiffACK is calculated.

  The data size for DiffACK can be obtained by, for example, (Equation 1).

Data size [Byte] for DiffACK = (payload of data size transmitted next by the data transmission terminal 14 when the data transmission terminal 14 receives the ACK packet of the notified ACK number) [Byte] + (Layer2 Header + Layer3 header + TCP header) [Byte] (Expression 1)
The ACK token management unit 27 that has calculated the data size for DiffACK subtracts the time T1 at which the latest ACK packet transferred to the data transmission terminal (recently transmitted ACK packet) is transmitted from the time T2 at which step 204 is completed. Based on the value and the data size for DiffACK, the token in the token bucket (ACK packet token bucket) corresponding to the flow is updated (step 205).

  The updated token amount can be obtained by, for example, (Equation 2).

Token amount after update [kB] = Token amount before update [kB] + guaranteed bandwidth [kbps] × (T2-T1) ÷ 8 [bits / Byte] −DiffACK data size [Byte] (Expression 2)
Here, (guaranteed bandwidth [kbps] × (T2−T1) ÷ 8 [bits / Byte]) is a data size that can pass through the guaranteed bandwidth from time T1 to time T2, and the data size for DiffACK is By subtracting from the passable data size, a value corresponding to the throughput between the data transmission terminal 14 and the data reception terminal 15 is obtained. That is, the updated token amount is calculated from the pre-update token amount and the throughput.

  At this time, if the updated token amount is larger than the token bucket size L [kB], the amount of the updated token amount [kB] exceeding L [kB] is added to the RTT measurement token bucket. .

  The ACK token management unit 27 that has performed the token update compares the token amount M [kB] in the RTT measurement token bucket with a preset threshold value X [kB] (step 206).

  When M [kB] is equal to or greater than X [kB], the ACK token management unit 27 notifies the window size calculation unit 26 of the user information of the service target flow, ΔT (= T2−T1), and the RTT measurement token bucket. A window size calculation request is output together with the token amount M (step 207). Further, the ACK token management unit 27 sets the tokens accumulated in the RTT measurement token bucket to 0 (step 208).

  Upon receiving the window size calculation request, the window size calculation unit 26 requests a guaranteed band corresponding to the user information from the band information holding unit 25 based on the user information (step 209). Then, the bandwidth information holding unit 25 returns the guaranteed bandwidth in response to the request from the window size calculation unit 26 (Step 210).

  When the guaranteed bandwidth is returned from the bandwidth information holding unit 25, the window size calculating unit 26 calculates a window size such that the data transmitting terminal 14 transmits data within the guaranteed bandwidth (step 211). At this time, a window size such that data is transmitted at a rate that matches the guaranteed bandwidth is preferable.

  The window size can be obtained by, for example, (Equation 3).

Window size [kB] = guaranteed bandwidth [kbps] × initial rewrite window size ÷ (guaranteed bandwidth [kbps] × ΔT−M [kB]) (Equation 3)
The initial rewrite window size is calculated based on a multiple of the maximum segment size (MSS) described as an option in the 3-way-handshake packet, or an RTT value measured using the 3-way-handshake packet. ).

Initial rewrite window size [kB] = guaranteed bandwidth [kbps] × RTT ÷ 8 [bits / Byte] (Expression 4)
Here, RTT is Round Trip Time (time from when data is transmitted until ACK is returned) generally used in TCP.

  Note that when the guaranteed bandwidth is set to the measurement value in Layer 2, the window size to be rewritten specifies the size in Layer 4, so (Equation 3) and (Equation 4) are the headers of Layer 2 as follows: (Equation 5) and (Equation 6) may be calculated in consideration of the size of Layer 3, the size of the header of Layer 3, and the size of the TCP header.

Window size [kB] = guaranteed bandwidth [kbps] × initial rewrite window size ÷ (guaranteed bandwidth [kbps] × ΔT−M [kB]) × (maximum segment size ÷ (maximum segment size + Layer 2 header size + Layer 3 header size + TCP) Header size)) ÷ 8 [bits / Byte] (Formula 5)
Initial rewrite window size [kB] = guaranteed bandwidth [kbps] × RTT ÷ 8 [bits / Byte] × (maximum segment size ÷ (maximum segment size + Layer2 header size + Layer3 header size + TCP header size)) ÷ 8 [bits / Byte] ... (Formula 6)
The window size utilizes the fact that the TCP throughput can be calculated from the band delay product (guaranteed band × RTT).

  FIG. 5 is a sequence diagram for explaining the processing from the calculation of the window size to the writing of the window size in the window size control method according to the present embodiment.

  First, the window size calculation unit 26 calculates the window size of the service target flow (step 301).

  Subsequently, the window size calculation unit 26 notifies the calculated window size and the user information of the service target flow to the advertisement window size writing unit 23 (step 302).

  The advertisement window size writing unit 23 writes the window size value notified from the window size calculation unit 26 into the window field of the ACK packet output from the flow identification / distribution unit 22 (step 303).

  Then, the advertising window size writing unit 23 outputs the ACK packet in which the window size value notified from the window size calculating unit 26 is written to the data transmitting unit 24.

  FIG. 6 is an image diagram showing how the ACK token bucket prepared for each control target TCP flow in the ACK token management unit 27 shown in FIG. 2 is updated.

  The numbers of ACK token buckets 40-1 to 40-n, burst sizes 41-1 to 41-n, and RTT measurement token buckets 42-1 to 42-n shown in FIG. 6 are numbers assigned for each flow. is there.

  In step 202 described above, the ACK number notified by the ACK number notification from the flow identification / distribution unit 22 to the token update instruction unit 45 of the ACK token management unit 27 flows to the flow information table 44 in the ACK number management unit 43. The received ACK number is stored together with the information (step 401). The flow information is specified by, for example, 5-tuple (destination address, transmission source address, destination port, transmission source port, protocol).

  Also, the token update jib 45 requests DiffACK calculation from the ACK number management unit 43 (step 402).

  The ACK number management unit 43 that has received the DiffACK calculation request from the token update instructing unit 45 determines the arrival ACK number and the ACK number of the latest ACK packet that has been transferred to the data transmission terminal already stored in the flow information table 44. DiffACK is calculated from the difference, and DiffACK notification is sent to the token update instruction unit 45 (step 403). Upon receiving the DiffACK notification, the token update instruction unit 45 updates the token amount in the corresponding token bucket based on the flow information of the ACK packet (step 404).

  As described above, in the present embodiment, the bandwidth is guaranteed by the bandwidth guarantee network 16 between the data transmission terminal 14 serving as the data transmission side and the data reception terminal 15 serving as the data reception side. Therefore, it is assumed that no packet is discarded as long as data is transmitted within the guaranteed bandwidth. Therefore, discarding packets can be prevented by adjusting the advertisement window size so that data is transmitted below the guaranteed bandwidth. If the packet discard does not occur, the congestion window size is not reduced. Therefore, the advertisement window size is always adopted as the TCP window size. As a result, the throughput does not fluctuate in a sawtooth shape, and the guaranteed bandwidth can be used efficiently.

  Therefore, in the present embodiment, the edge nodes 11 and 12 between the data transmission terminal 14 and the data reception terminal 15 are determined based on the throughput between the data transmission side and the data reception side and the guaranteed bandwidth by the bandwidth guarantee network. Is transmitted within the guaranteed bandwidth, and the advertisement window size described in the ACK packet transmitted from the data receiving terminal 15 to the data transmitting terminal 14 is rewritten to the calculated window size value.

  As a result, the rate of data transmitted from the data transmission terminal 14 to the data reception terminal 15 can be stably controlled within the guaranteed bandwidth, so that the guaranteed bandwidth can be efficiently used.

  In addition, the edge nodes 11 and 12 measure the current data throughput based on the ACK number, and calculate the current propagation delay time based on the measured throughput, so that the queuing delay and the delay fluctuation due to the delayed ACK algorithm are calculated. Thus, it is possible to maintain the high throughput by efficiently using the guaranteed bandwidth.

  Note that the processing performed by each component provided in the edge nodes 11 and 12 described above may be performed by a logic circuit manufactured according to the purpose. Further, a program describing processing contents may be recorded on a recording medium readable by the edge nodes 11 and 12, and the program recorded on the recording medium may be read by the edge nodes 11 and 12 and executed. good. The recording media readable by the edge nodes 11 and 12 include transferable recording media such as a floppy (registered trademark) disk, a magneto-optical disk, a DVD, and a CD, and a ROM built in the edge nodes 11 and 12. , Memory such as RAM, HDD, and the like. The program recorded on the recording medium is read by a CPU (not shown) in the edge nodes 11 and 12, and the same processing as described above is performed under the control of the CPU. Here, the CPU operates as a computer that executes a program read from a recording medium on which the program is recorded.

11, 12 Edge node 13 Band management server 14 Data transmission terminal 15 Data reception terminal 16 Band guarantee network 21 Data reception unit 22 Flow identification / distribution unit 23 Advertising window writing unit 24 Data transmission unit 25 Band information holding unit 26 Window size calculation unit 27 ACK token management unit 40-1 to 40-n ACK token bucket 41-1 to 41-n burst size 42-1 to 42-n RTT measurement token bucket 43 ACK number management unit 44 flow information table 45 token update instruction unit

Claims (9)

An edge node connected between the data transmission terminal and the data reception terminal, connected to a bandwidth guarantee network in which a communication band between the data transmission terminal and the data reception terminal is guaranteed,
A bandwidth information holding unit for holding a guaranteed bandwidth, which is the guaranteed communication bandwidth, for each service target flow;
An ACK (Acknowledgement) packet token bucket and an RTT (Round Trip Time) measurement token bucket for each service target flow, and measure the throughput of data transmitted from the data transmission terminal to the data reception terminal; The token amount in the token bucket for the ACK packet is updated based on the throughput, and when the updated token amount exceeds the size of the token bucket for the ACK packet, the token amount exceeds the size of the token bucket for the ACK packet If the token amount for the RTT measurement token bucket is added to the RTT measurement token bucket and the token amount in the RTT measurement token bucket is equal to or greater than a preset threshold, the window size is a request for calculating the window size. After outputting the output request, and ACK token management unit for setting the amount of tokens in the RTT measurement token bucket to zero,
When the ACK token management unit outputs the window size calculation request , the guaranteed bandwidth, the token amount before being set to zero in the RTT measurement token bucket, the data transmitting terminal, and the data receiving terminal A window size calculation unit that calculates a window size based on the propagation delay time between
An edge having an advertising window size writing unit that rewrites the window size indicated in the ACK packet transmitted from the data receiving terminal to the data transmitting terminal in the service target flow with the window size calculated by the window size calculating unit node. The edge node according to claim 1,
A flow for identifying whether or not the data packet transmitted from the data receiving terminal is the ACK packet, and when identifying that the data packet is an ACK packet, a flow for notifying the ACK number indicated in the ACK packet It has an identification / sorting section,
The ACK token management unit transmits the ACK number notified from the flow identification / distribution unit, the ACK number indicated by the ACK packet recently transferred to the data transmission terminal, and the ACK packet recently transferred to the data transmission terminal. An edge node characterized in that the throughput is calculated based on a time from time to time of the notification and the guaranteed bandwidth. The edge node according to claim 1,
The window size calculation unit calculates the propagation delay time by using a 3-way-handshake packet. A window size control method in an edge node that is connected to a bandwidth guarantee network in which a communication band between a data transmission terminal and a data reception terminal is guaranteed, and is provided between the data transmission terminal and the data reception terminal. ,
A process of holding a guaranteed bandwidth that is the guaranteed communication bandwidth for each service target flow;
A process for measuring the throughput of data transmitted from the data transmitting terminal to the data receiving terminal;
A process of updating the token amount in the token bucket for ACK (Acknowledgement) packets provided for each of the service target flows based on the throughput;
When the updated token amount exceeds the size of the token bucket for the ACK packet, the amount of tokens exceeding the size of the token bucket for the ACK packet is set to RTT (Round Trip) provided for each service target flow. (Time) processing to add to the token bucket for measurement,
When the token amount in the RTT measurement token bucket is equal to or greater than a preset threshold value , the guaranteed bandwidth, the token amount in the RTT measurement token bucket, and between the data transmitting terminal and the data receiving terminal Processing for calculating the window size based on the propagation delay time in
After calculating the window size, a process of setting the token amount in the RTT measurement token bucket to zero;
A window size control method comprising: rewriting a window size indicated in an ACK packet transmitted from the data receiving terminal to the data transmitting terminal in the service target flow to the calculated window size. The window size control method according to claim 4,
A process of identifying whether the data packet transmitted from the data receiving terminal is an ACK packet;
When the data packet is identified as an ACK packet, the ACK number indicated by the ACK packet, the ACK number indicated by the ACK packet recently transferred to the data transmission terminal, and the ACK packet recently transferred to the data transmission terminal are transmitted. A window size control method comprising: processing for calculating the throughput based on a time from when the identification is performed to the identification and the guaranteed bandwidth. The window size control method according to claim 4,
The window size control method characterized by having the process which calculates the said propagation delay time using a 3 way-handshake packet. An edge node provided between the data transmitting terminal and the data receiving terminal is connected to a bandwidth guaranteed network in which a communication band between the data transmitting terminal and the data receiving terminal is guaranteed,
A procedure for maintaining a guaranteed bandwidth, which is the guaranteed communication bandwidth, for each service target flow;
A procedure for measuring the throughput of data transmitted from the data transmitting terminal to the data receiving terminal;
Updating the token amount in the token bucket for an ACK (Acknowledgement) packet provided for each service target flow based on the throughput;
When the updated token amount exceeds the size of the token bucket for the ACK packet, the amount of tokens exceeding the size of the token bucket for the ACK packet is set to RTT (Round Trip) provided for each service target flow. Time) to add to the token bucket for measurement,
When the token amount in the RTT measurement token bucket is equal to or greater than a preset threshold value , the guaranteed bandwidth, the token amount in the RTT measurement token bucket, and between the data transmitting terminal and the data receiving terminal A procedure for calculating the window size based on the propagation delay time in FIG.
After calculating the window size, a procedure for setting the token amount in the token bucket for RTT measurement to zero,
A program for executing a procedure for rewriting a window size indicated in an ACK packet transmitted from the data receiving terminal to the data transmitting terminal in the service target flow with the calculated window size. The program according to claim 7,
A procedure for identifying whether a data packet transmitted from the data receiving terminal is an ACK packet;
When the data packet is identified as an ACK packet, the ACK number indicated by the ACK packet, the ACK number indicated by the ACK packet recently transferred to the data transmission terminal, and the ACK packet recently transferred to the data transmission terminal are transmitted. A program for executing a procedure for calculating the throughput on the basis of a time from when the identification is made to the identification and the guaranteed bandwidth. The program according to claim 7,
A program for executing a procedure for calculating the propagation delay time using a 3-way-handshake packet.

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