JP2015095680A - Communication device and communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To resolve discrepancy even if the discrepancy occurs in RTT measured by WAN acceleration devices.SOLUTION: A communication system comprises a WAN acceleration device 100A placed between a first network and a second network, and a WAN acceleration device 100B placed between the second network and a third network. The WAN acceleration devices 100A, 100B each comprise a measuring unit 120 that measures a communication delay time including a device retention time of their own device regarding communication from a device on the first network to a device on the third network via the second network, and a notification unit 105 that notifies an opposite device of the communication delay time including the device retention time.

Description

  The present invention relates to a communication apparatus and a communication system, and more particularly, to an apparatus and a system for performing band control for communication between terminals.

  TCP (Transmission Control Protocol) is generally used in terminal-to-terminal communication in an IP (Internet Protocol) network connecting bases scattered around the world.

  In TCP, when a data packet arrives safely from the transmission side terminal to the reception side terminal, an acknowledgment is returned from the reception side terminal to the transmission side terminal. This ensures high communication reliability. In addition, the amount of data that can be transmitted from the start of data packet transmission to the reception of the first confirmation response is limited in the transmission side terminal, and this data amount is called a window size.

  When the RTT (Round Trip Time) decreases and the packet discard rate decreases, the transmitting terminal determines that the network condition is good, increases the window size, and indirectly improves the effective bandwidth. However, if the RTT increases and the packet discard rate increases, it is determined that the network condition has deteriorated, the window size is reduced, and the effective bandwidth is indirectly reduced. As described above, the RTT and the packet discard rate greatly influence the increase / decrease of the window size, and as a result, the effective bandwidth of the network is greatly influenced.

In recent years, devices that perform bandwidth control, such as preventing an event that the effective bandwidth is reduced due to an increase in RTT and an increase in the packet discard rate, and maintaining the effective bandwidth, have been developed and are becoming popular under the name of WAN acceleration devices. .
The technology of Patent Document 1 has already been put into practical use as the core technology of the above-described devices.

International publication number: WO2011 / 033894

  In the WAN acceleration device using the technique of Patent Document 1, bandwidth control is performed in a WAN environment with a high packet discard rate and a long RTT to suppress a decrease in effective bandwidth. A large amount of buffers are allocated to this bandwidth control. Yes. A difference in effective bandwidth between a LAN (Local Area Network) and a WAN (Wide Area Network) is absorbed by storing packet data in a buffer. However, if it takes time to output packet data from the buffer, such as stopping packet transmission from the buffer to the WAN side or extending the packet data processing in the buffer of the WAN acceleration device, the RTT will increase accordingly. This may affect the behavior of the WAN acceleration device. Examples of possible effects are given below.

  For example, when one-way data communication is performed, or when the communication amount in one direction is larger than the communication amount in the other direction, only one WAN acceleration device among the opposite WAN acceleration devices increases the RTT. As a result, the RTT may be wrinkled by the WAN acceleration devices on both sides. In the WAN acceleration device, the buffer amount necessary for the acceleration is calculated and dynamically changed, but RTT (between WAN acceleration communication devices) is included in the parameters of this calculation formula. For this reason, different RTTs are held between devices that increase the speed of data communication, and the amount of buffer calculated in real time from the calculation formula also becomes wrinkled.

  It is desirable to reduce the possibility that such drought will adversely affect the behavior of the WAN acceleration device.

  In view of the above points, an object of the present invention is to eliminate a wrinkle even if a wrinkle occurs in the RTT measured by each WAN acceleration device.

According to the first solution of the present invention,
The communication device in a communication system comprising a communication device disposed between a first network and a second network, and a counter device disposed between the second network and a third network,
A communication unit that relays a packet received from the first network device to the second network and transmits the packet to the third network device;
For the packet, a measurement unit that measures a communication delay time including a device residence time of the device,
There is provided a communication device including a notification unit that notifies the opposite device of a communication delay time including a device residence time.

According to the second solution of the present invention,
A first communication device disposed between the first network and the second network;
A second communication device disposed between the second network and the third network and facing the first communication device;
The first communication device and the second communication device are:
A communication unit that relays a packet received from a device of the first or third network to the second network and transmits the packet to the device of the third or first network;
For the packet, a measurement unit that measures a communication delay time including a device residence time of the device,
There is provided a communication system including a notifying unit that notifies the second or first communication device facing the communication delay time including the device residence time.

  According to the present invention, even if a wrinkle occurs in the RTT measured by each WAN acceleration device, the wrinkle can be eliminated.

1 is a block diagram of a WAN acceleration device. The format figure of connection management information. FIG. 3 is a sequence diagram from 3WHS (3-way handshake) to transmission of an RTT notification packet. The flowchart which determines whether RTT notification is performed and transmits an RTT notification packet to a WAN acceleration device.

One mode for carrying out the present invention is as follows.
The WAN acceleration device connected to the transmission side terminal measures the RTT between the own device and the WAN acceleration device connected to the reception side terminal from the response during data communication, and the measured RTT to the reception side terminal A means for determining whether or not to notify the connected WAN acceleration device of the RTT held by the own device and the determination result of whether or not to perform the RTT notification are sent to the device connected to the receiving terminal. Means.

FIG. 1 shows an embodiment of a communication system and a WAN acceleration device 100 that performs RTT notification.
The communication system includes a WAN acceleration device (first communication device) 100A and a WAN acceleration device (second communication device, opposite device) 100B facing the WAN acceleration device 100A. The WAN acceleration device 100A is connected to the terminal 101A via a network (first network) such as a LAN, for example, and is connected to the WAN acceleration device 100B via a network of a unique protocol (second network). For example, the WAN acceleration device 100B is connected to the terminal 101B via a network such as a LAN (third network), and is connected to the WAN acceleration device 100A via a network (second network) of a unique protocol as described above. . The WAN acceleration device 100 </ b> A and the WAN acceleration device 100 </ b> B perform bandwidth control like the technique disclosed in Patent Document 1, for example. Here, two WAN acceleration devices facing each other will be described as an example, but the communication system may include three or more WAN acceleration devices facing each other.

  FIG. 1 is a block diagram showing the configuration of the apparatus 100A. The WAN optimizer 100A receives a packet transmitted by the terminal 101A as an input, and outputs a TX unit (transmitter) 102 that outputs the packet to the WAN optimizer 100B, and a packet transmitted from the WAN optimizer 100B as an input. RX unit (reception unit) 103 that receives and outputs a packet to terminal 101A, and connection management information storage unit 104 that TX unit 102 and RX unit 103 use in common, and the device residence time of its own device for a packet to be relayed The measurement unit 120 that measures the communication delay time (corrected RTT) including the information and the information registered in the connection management information storage unit 104 determines whether to perform RTT notification, and determines the RTT via the transmission unit 102 according to the determination result. An RTT notification determination unit (notification unit) 105 for notifying the opposite WAN acceleration device 100B, and R And a processing unit 130 which performs predetermined processing based on the T. The processing in the processing unit 130 may be, for example, processing for buffer amount calculation and bandwidth control, or other appropriate processing based on RTT. In the present specification, the TX unit 102 and the RX unit 103 may be collectively referred to as a communication unit.

  The TX unit 102 includes a transmission packet input processing unit 106, a transmission control unit 107 that controls transmission of each packet, and a transmission packet output processing unit 108.

  The RX unit 103 includes a received packet input processing unit 109 and a received packet output processing unit 110.

  Note that the configuration of the WAN acceleration device 100B is the same as that of the WAN acceleration device 100A, and a description thereof will be omitted.

FIG. 2 shows a format of the connection management information storage unit 104.
The connection information storage unit 104 includes a connection ID 201, a SYN packet transmission time 202, a SYN-ACK packet reception time 203, an initial RTT 204, a data packet reception time 205, an ACK packet reception time 206, and a modified RTT 207. Remembered.

  FIG. 3 is a sequence diagram from 3WHS to transmission of an RTT notification packet. The operation of the WAN acceleration device 100A will be mainly described with reference to FIGS. The operation of the facing WAN acceleration device 100B is the same.

  When data is transmitted from the terminal 101A to the terminal 101B, first, the transmission packet input processing unit 106 receives the SYN packet transmitted from the terminal 101A (S201), and passes the SYN packet to the transmission control unit 107.

  The transmission control unit 107 passes the SYN packet to the transmission packet output processing unit 108, and the transmission packet output processing unit 108 outputs the received SYN packet to the WAN optimizer 100B (S102). The transmission packet output processing unit 108 registers the transmission time 202 of the SYN packet in the newly created entry in the connection management information storage unit 104.

  The SYN packet is transferred from the WAN acceleration device 100B to the terminal 101B (S103).

  When the received packet input processing unit 109 receives the SYN-ACK packet transmitted from the terminal 101B in response to the SYN packet (S104) and passes through the WAN optimizer 100B (S105), the reception time of the SYN-ACK packet Is registered in the entry of the connection management information storage unit 104, and the received SYN-ACK is passed to the packet output processing unit 110.

  The received packet output processing unit 110 outputs the received SYN-ACK packet to the terminal 101A (S106).

  When the SYN-ACK packet reception time is registered in the connection management information storage unit 104, the measurement unit 120 performs an initial RTT (second communication delay) measured from the difference between the SYN packet transmission time 202 and the SYN-ACK packet reception time 203. Time) 204 is registered in the entry. In addition, the measurement unit 120 registers a connection ID 201 that identifies a connection between terminals.

  When receiving an ACK packet for the SYN-ACK packet from the terminal 101A (S107), the transmission packet input processing unit 106 passes the ACK packet to the transmission control unit 107.

  The transmission control unit 107 passes the ACK packet to the transmission packet output processing unit 108, and the ACK packet is transmitted from the transmission packet output processing unit 108 to the WAN optimizer 100B (S108). The ACK packet is transferred from the WAN optimizer 100B to the terminal 101B (S109).

FIG. 4 shows a flowchart for transmitting and receiving data packets. The description will be continued below with reference to FIG.
When actually transmitting data from the terminal 101A to the terminal 101B, the transmission packet input processing unit 106 receives the data packet transmitted from the terminal 101A (S110), and registers the data packet reception time 205 in the connection management information storage unit 104. Then, the data packet is transferred to the transmission control unit 107 (S201).

  The transmission control unit 107 passes the data packet to the transmission packet output processing unit 108, and the transmission packet output processing unit 108 outputs the received data packet to the WAN optimizer 100B (S112, S202). The data packet is transferred from the WAN acceleration device 100B to the terminal 101B. Note that the WAN optimizer 100A may transmit a proxy ACK packet to the terminal 101 (S111, S203).

  When the received packet input processing unit 109 receives the ACK packet transmitted from the terminal 101B in response to the data packet (S114) and received through the WAN optimizer 100B (S115), the reception packet input processing unit 109 sets the reception time of the ACK packet to the connection management information. The entry is registered in the entry of the storage unit 104 (S204).

  When the ACK packet reception time 206 is registered in the connection management information storage unit 104, the measurement unit 120 includes a communication delay including the device residence time of the own device measured from the difference between the data packet reception time 205 and the ACK packet reception time. The corrected RTT, which is the time, is calculated and registered in the entry, and the corrected RTT is passed to the RTT notification determination unit 105 (S205).

  In this embodiment, the corrected RTT (communication delay time considering the device retention) is the device retention time of the packet in the device itself and the communication from when the packet is transmitted from the device until the ACK packet is returned. This is a delay time including a delay time. In addition, the device residence time may not include the entire time from when the device receives the packet until it is transmitted, and may measure a part of the time that the packet stays in the device. On the other hand, the initial RTT is a communication delay time obtained from a SYN packet or the like, and can be obtained in the same manner as in the past. As described above, the WAN acceleration device 100A may measure, or the WAN acceleration device 100A may receive and use the initial RTT measured by another device.

  The RTT notification determination unit 105 compares the corrected RTT with a preset threshold (S206), and when the corrected RTT is larger than the threshold, the transmission control unit 107 determines the determination result for RTT notification and the corrected RTT information. (S116).

  The threshold value may be set to a predetermined appropriate value, or may be set based on the initial RTT. For example, the RTT may be notified when the difference from the initial RTT exceeds a predetermined value, or the RTT may be notified when the variation rate from the initial RTT exceeds a predetermined value. When setting a threshold value based on the initial RTT, for example, the measurement unit 120 sets the threshold value.

  Upon receiving the determination result for the RTT notification, the transmission control unit 107 passes the RTT notification packet including the corrected RTT to the transmission packet output processing unit 108, and the transmission packet output processing unit 108 outputs the RTT notification packet to the apparatus 100B ( S117, S207). As the RTT notification packet, a health check packet transmitted between the WAN acceleration devices 100A and 100B may be used, or another periodically transmitted / received packet may be used. Thereby, an increase in traffic due to the RTT notification can be suppressed.

  If the corrected RTT is not larger than the threshold value (S206), the RTT notification may not be performed (S208).

The above-described processing is also performed in the WAN acceleration device 100B, and the WAN acceleration device 100A receives the RTT notification from the WAN acceleration device 100B. For example, the RX unit 103 receives a modified RTT (third communication delay time) including the device residence time in the WAN acceleration device 100B, which is measured by the WAN acceleration device 100B that is the opposite device. The RTT processing unit 130 uses the second communication delay time including the received device residence time for a predetermined process using the measured communication delay time. The RTT processing unit 130 also includes a communication delay time including the device residence time in the own device, and a second communication delay time including the device residence time in the WAN acceleration device 100B received from the WAN acceleration device 100B that is the opposite device. And the longer or shorter one may be used. By matching the conditions for adopting the communication delay time between the WAN acceleration devices 100A and 100B, even if the communication delay times due to the RTT notifications from both are different, it is possible to avoid the communication delay time to be adopted.
Note that the RTT notification packet from the WAN acceleration device 100A is similarly processed by the WAN acceleration device 100B.

  As described above, the WAN acceleration device that performs communication delay notification (RTT notification) including the device residence time of the device itself is realized. Thereby, even when the device residence time in the WAN acceleration device fluctuates, it is possible to correct the RTT defect that has occurred between the WAN acceleration devices in communication. Further, the WAN speed-up device performs buffer calculation using RTT as a parameter, but the effect of stabilizing the behavior of the WAN speed-up device can also be obtained by eliminating the RTT trap.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of the embodiment.

  Each of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit. Each of the above-described configurations, functions, and the like may be realized by software by interpreting and executing a program that realizes each function by the processor. Information such as programs, tables, and files for realizing each function can be stored in a memory, a hard disk, a recording device such as an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, or a DVD.

  Further, the control lines and information lines indicate what is considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

100 apparatus 101 terminal 102 TX section (transmission section)
103 RX section (receiving section)
104 Connection management information storage unit 105 RTT notification determination unit (notification unit)
107 Transmission Control Unit 120 Measurement Unit 130 Processing Unit

Claims (13)

The communication device in a communication system comprising a communication device disposed between a first network and a second network, and a counter device disposed between the second network and a third network,
A communication unit that relays a packet received from the first network device to the second network and transmits the packet to the third network device;
For the packet, a measurement unit that measures a communication delay time including a device residence time of the device,
A communication apparatus comprising: a notification unit that notifies the opposite apparatus of a communication delay time including an apparatus residence time. The measurement unit calculates a communication delay time including the device residence time,
The reception time of the packet from the first network;
The communication apparatus according to claim 1, wherein the packet is transmitted to the second network, and is measured by a difference from a reception time of an acknowledgment response to the packet returned via the third network.   The communication device according to claim 1, wherein when the communication delay time including the device residence time is greater than a preset threshold, the notification unit notifies the opposite device of the communication delay time including the device residence time. The measurement unit measures a second communication delay from when the second packet is transmitted to the second network to when the confirmation response is received, measured with respect to communication between the device of the first network and the device of the third network. Measure time,
The communication device according to claim 3, wherein the threshold is set based on a second communication delay time. The communication unit receives a third communication delay time measured by the opposite device and including a device residence time in the opposite device;
The communication device
The communication device according to claim 1, further comprising a processing unit that uses a third communication delay time including the received device residence time for a predetermined process using the communication delay time.   The communication device according to claim 1, wherein the notification unit notifies a communication delay time including a device residence time in a health check packet with the opposite device. A first communication device disposed between the first network and the second network;
A second communication device disposed between the second network and the third network and facing the first communication device;
The first communication device and the second communication device are:
A communication unit that relays a packet received from a device of the first or third network to the second network and transmits the packet to the device of the third or first network;
For the packet, a measurement unit that measures a communication delay time including a device residence time of the device,
A communication system comprising: a notification unit that notifies a communication delay time including a device residence time to the opposing second or first communication device. The measurement unit calculates a communication delay time including the device residence time,
The reception time of the packet from the first or third network;
The communication system according to claim 7, wherein the packet is transmitted to the second network, and is measured by a difference from a reception time of an acknowledgment response to the packet returned through the third or first network.   The said notification part notifies the said 1st or 2nd communication apparatus which opposes the communication delay time containing this apparatus residence time when the communication delay time containing an apparatus residence time is larger than the preset threshold value. The communication system according to 1. The measurement unit measures a second communication delay from when the second packet is transmitted to the second network to when the confirmation response is received, measured with respect to communication between the device of the first network and the device of the third network. Measure time,
The communication system according to claim 9, wherein the threshold is set based on a second communication delay time. The communication unit receives a third communication delay time including a device residence time in the device, measured by the first or second communication device facing the device;
The first communication device and the second communication device are:
The communication system according to claim 7, further comprising: a processing unit that uses a third communication delay time including the received device residence time for a predetermined process using the communication delay time.   8. The communication system according to claim 7, wherein the notification unit includes a communication delay time including a device residence time in a health check packet with the opposing first or second communication device. The communication unit receives a third communication delay time including a device residence time in the device, measured by the first or second communication device facing the device;
The first communication device and the second communication device are:
Compare the first communication delay time measured by the own device with the third communication delay time measured by the opposite device for a predetermined process using the communication delay time, whichever is longer or shorter The communication system according to claim 7, further comprising a processing unit that uses the method.

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