JP4430597B2 - NETWORK SYSTEM, TRANSMITTER DISTRIBUTION DEVICE, PACKET COMMUNICATION METHOD, AND PACKET COMMUNICATION PROGRAM - Google Patents

Description

  The present invention relates to a network system, a transmission-side distribution device, a packet communication method, and a packet communication program.

  The quality of a link as a network line is defined by, for example, bandwidth, delay, and reliability (packet loss rate, etc.), and is established as an evaluation measure for communication services. Multi-links can simultaneously use a plurality of links to widen the bandwidth, reduce delay, and improve communication reliability. As a protocol that enables simultaneous use of multilinks, multilink PPP (Point to Point Protocol) (Non-Patent Document 1), link aggregation (Non-Patent Document 2), and the like are generally used. However, these protocols are based on the assumption that the link quality is constant or that all the links have the same quality.

  However, in recent years, the spread of wireless networks has expanded. A wireless network is characterized by a large change in communication quality. There is a need for a technology that uses various links including links of these wireless networks as a multilink together with a wired network with a small change in communication quality. Since the existing protocol cannot dynamically allocate packets to each link according to the link quality that changes from time to time, even if a plurality of links are used at the same time, sufficient bandwidth cannot be expected.

  As another existing technique that enables simultaneous use of multilinks, the invention described in Patent Document 1 is free in each interface connected to each of a plurality of links (not transmitting). ) It relates to a method of selecting an interface. However, if the link bandwidth or delay changes from time to time, an empty interface does not necessarily mean that the link connected to that interface has the best link bandwidth or delay status compared to other links. do not do.

  For example, when the delay of a specific link among a plurality of existing links is significantly larger than that of other links, the end-to-end communication efficiency is higher when a packet is transmitted using a link other than the specific link. As a result, the interface connected to the specific link is constantly free. In other words, the invention described in Patent Document 1 cannot solve the problem of improving the bandwidth by simultaneously using various links including links whose delay and bandwidth vary.

  In addition, communication terminals that are generally used are premised on performing communication using a single link, and a multi-link is provided to these widely used communication terminals to easily realize a wide band. For this purpose, a system that realizes multi-link utilization by arranging an apparatus on a link without requiring an additional function in the communication terminal is desirable.

For example, the invention described in Patent Document 2 is a method for transmitting the transmission data by dividing the size of the transmission data by the number of links, and this method needs to implement a desired function in a packet transmission terminal. In addition, since the output destination link cannot be changed for each packet according to the link quality that changes every moment, the bandwidth cannot be sufficiently improved even if a plurality of links are used simultaneously.
JP 2001-244982 A JP 2002-94595 A IETF, “The PPP Multilink Protocol (MP)”, [online], [searched on July 28, 2005], Internet <URL: http://www.ietf.org/rfc/rfc1717.txt> IEEE Standards Association, “IEEE P802.3ad Link Aggregation Task Force”, [online], [searched on July 28, 2005], Internet <URL: http://www.ieee802.org/3/ad/index. html>

  The conventional method using the multilink described above is based on the premise that the link quality is constant and the like, and dynamic packet allocation corresponding to a change in the link quality is impossible. In view of the above, the main object of the present invention is to solve the above-described problems and to realize a broadband communication from a transmission terminal to a reception terminal in a multilink including a link whose communication quality varies. A second object is to realize the object without requiring any additional function for the transmitting terminal and the receiving terminal.

In order to solve the above-described problem, the present invention provides a packet transmitted from a transmission terminal and arriving at a reception terminal from the transmission-side distribution device via the reception-side distribution device. A network system that flows on a multilink that bundles a plurality of links between receiving distribution devices, wherein the transmitting distribution device receives an interface that receives a packet transmitted from the transmission terminal, and the multilink. A link monitoring unit that calculates an expected reception time of the packet to the receiving side distribution device based on the communication quality of the monitored link for each link that constitutes the link, and the expected reception for each link that constitutes the multilink time possess a distribution processing section for determining the destination link earliest links, and a tunneling processor to transmit the packet to the destination link, the link The viewing unit calculates a link reference transmission interval from the transmission interval of the packet transmitted by the transmission-side distribution device and the reception interval of the packet received by the reception-side distribution device, and the reception time of the packet transmitted immediately before and The sum of the reference transmission intervals of the link is set as the expected reception time .

As a result, in a multilink including a link whose communication quality fluctuates, the link with the earliest expected reception time is selected as the transmission destination link, so that it is possible to realize a wideband communication from the transmission terminal to the reception terminal. . Also, the expected reception time can be calculated by accurately identifying the communication quality of the fluctuating link.

  In the present invention, the tunneling processing unit transmits each packet with an individual sequence number for identifying each packet to be transmitted for each link, and the receiving side distribution device transmits the individual sequence of the received packet. A retransmission processing unit for detecting a packet loss based on the number and requesting a retransmission of a packet that could not be received due to the packet loss. It is characterized by resending.

  Thereby, even if packet loss occurs in each link, communication reliability can be guaranteed.

  In the present invention, the tunneling processing unit attaches each packet with an overall sequence number for identifying each packet to be transmitted for each multilink, and the receiving-side distribution device transmits the received packet in the received packet. An arrangement processing unit is provided that arranges the packet order based on the entire sequence number and transmits the packet to the receiving terminal.

  As a result, even if the packet transmission order is changed in the multilink, communication is performed in the correct order.

  In the present invention, when the alignment processing unit aligns packets, it detects a packet loss based on the entire sequence number, makes a retransmission request for a packet that could not be received due to the packet loss, and The apparatus receives the packet retransmission request and retransmits the corresponding packet.

  Thereby, even if packet loss occurs in the multilink, the reliability of communication can be guaranteed.

  The present invention is characterized in that the transmission-side distribution device temporarily stops communication via a link in which packet loss frequently occurs.

  Thereby, a link with low reliability can be excluded from communication, and the communication efficiency of the entire multilink can be improved.

  According to the present invention, the transmission terminal and the transmission-side distribution device are accommodated in the same housing, and the distribution processing unit sets a transmission destination link according to an application identifier described in header information of a packet to be transmitted. It is characterized by determining.

  Thereby, the communication quality according to the characteristic of application data can be provided.

  According to the present invention, the transmission-side distribution device and the reception-side distribution device are each configured with redundancy by a plurality of cases, and the link monitoring unit of each case is connected to the link monitoring unit of another case. The communication quality of the links is exchanged with each other, and the transmission side distribution devices monitor each other so as to detect a failure between the constituting housings, and when a predetermined housing fails, other housings communicate packets. Acting as a substitute, the receiving-side distribution device monitors each other so that a failure is detected between the constituent housings, and when a predetermined housing fails, the other housing acts as a proxy for packet communication .

  As a result, even if one housing fails, the network system can continue to operate.

  The present invention relates to a first TCP session between the transmission terminal and the transmission-side distribution device, wherein the transmission-side distribution device and the reception-side distribution device have a TCP session between the transmission terminal and the reception terminal, A second TCP session is created between the receiving terminal and the receiving side distribution device.

  Thereby, it is possible to use communication parameters suitable for the characteristics of the network to which the transmitting terminal and the receiving terminal are connected, and it is possible to improve the throughput.

  In the present invention, the link monitoring unit calculates a required time of the link from a difference between a transmission time of a packet transmitted by the transmission-side distribution device and a reception time of a packet received by the reception-side distribution device, The sum of the time and the required time of the link is set as a first expected reception time, and the reference transmission of the link is determined based on the transmission interval of packets transmitted by the transmission-side distribution device and the reception interval of packets received by the reception-side distribution device. The interval is calculated, and the sum of the reception time of the packet transmitted immediately before and the reference transmission interval of the link is set as the second expected reception time, and the later of the first expected reception time and the second expected reception time is the packet. The predicted reception time of

  Thus, by specifying the expected reception time from the two calculation results, a highly accurate value can be adopted.

  In the present invention, if the link monitoring unit calculates the reference transmission interval of the link, if the transmission interval and the reception interval are equal, the link reference transmission interval may be set to a smaller value than the current value, and the transmission interval may be smaller than the reception interval. For example, the reference transmission interval of the link is updated to a value larger than the current value.

  As a result, it is possible to accurately determine the communication quality of the fluctuating link and calculate the expected reception time.

  The present invention is characterized in that the tunneling processing unit transmits a packet within a transmission interval of a reference transmission interval of the link calculated by the distribution processing unit.

  Thereby, packet loss can be reduced by limiting the amount of communication to an amount suitable for the capability of the communication resource, and highly reliable communication can be realized.

  The present invention is characterized in that the tunneling processing unit uses, as a packet to be transmitted, a packet transmitted from the transmission terminal or a measurement packet created by the transmission-side distribution device.

  Thereby, the reference transmission interval of the link can be maintained.

  The present invention is characterized in that the tunneling processing unit transmits a packet with the shortest transmission interval that can be transmitted from a link.

  Thereby, communication resources can be used efficiently.

The present invention relates to a packet transmitted from a transmission terminal and arriving at a reception terminal from a transmission-side distribution device via a reception-side distribution device between the transmission-side distribution device and the reception-side distribution device. The transmission-side distribution device used in a network system that flows on a multilink that bundles a plurality of links, the interface that receives a packet transmitted from the transmission terminal, and each link that constitutes the multilink is monitored A link monitoring unit that calculates an expected reception time of the packet to the receiving side distribution device based on the communication quality of the link and a link with the earliest expected reception time for each link constituting the multilink. possess a distribution processing section for determining first link, and a tunneling processor to transmit the packet to the destination link, the link monitoring unit, the transmission The reference transmission interval of the link is calculated from the transmission interval of the packet transmitted by the distribution device and the reception interval of the packet received by the receiving-side distribution device, and the reception time of the packet transmitted immediately before and the reference transmission interval of the link are calculated. The sum is the expected reception time .

  As a result, in a multilink including a link whose communication quality fluctuates, the link with the earliest expected reception time is selected as the transmission destination link, so that it is possible to realize a wideband communication from the transmission terminal to the reception terminal. .

  The present invention is characterized in that the transmission-side distribution device has the configuration of the reception-side distribution device.

  Thereby, communication in both directions is possible in transmission and reception.

The present invention relates to a packet transmitted from a transmission terminal and arriving at a reception terminal from a transmission-side distribution device via a reception-side distribution device between the transmission-side distribution device and the reception-side distribution device. A packet communication method by a network system that flows on a multi-link that bundles a plurality of links, wherein the transmission-side distribution device receives a packet transmitted from the transmission terminal, and each link that constitutes the multi-link The procedure for calculating the expected reception time of the packet to the receiving side distribution device based on the communication quality of the monitored link, and for each link constituting the multilink, the link with the earliest expected reception time is a procedure for determining the destination link, perform the step of transmitting the packet to the destination link, the procedure for calculating the predicted reception time, the transmission-side sorting instrumentation The link reference transmission interval is calculated from the transmission interval of the packet transmitted by the receiver and the reception interval of the packet received by the receiving side allocating device, and the sum of the reception time of the packet transmitted immediately before and the reference transmission interval of the link is calculated. The expected reception time is used .

  As a result, in a multilink including a link whose communication quality fluctuates, the link with the earliest expected reception time is selected as the transmission destination link, so that it is possible to realize a wideband communication from the transmission terminal to the reception terminal. .

  The present invention is a packet communication program for causing a computer to execute the packet communication method.

  As a result, in a multilink including a link whose communication quality fluctuates, the link with the earliest expected reception time is selected as the transmission destination link, so that it is possible to realize a wideband communication from the transmission terminal to the reception terminal. .

  By using the present invention, when a transmission terminal transmits a packet to a reception terminal, a plurality of links exist between the transmission-side distribution device and the reception-side distribution device. Even if the communication quality changes every moment, the transmission side distribution device always knows the quality of each link, so each packet will be received via the link that arrives earliest at that time. Delivered to sorting device and receiving terminal. Therefore, the effective communication speed from the transmission terminal to the reception terminal is widened.

  In addition, by allocating packets to each link in consideration of the standard transmission interval of packets, for example, when the transmission delay of a specific link among a plurality of links is small and the bandwidth is narrow, the packet is biased toward a specific link. Can be prevented from causing congestion on this link.

  Also, in the transmission side distribution device, by controlling the transmission interval of the packets transferred to the reception side distribution device, packets are transmitted to each link without exceeding the reference transmission interval of that link. The occurrence of congestion in each link can be suppressed.

  Further, according to the present invention, it is not necessary to implement an additional function in order to use a plurality of links in a transmission terminal and a reception terminal that are packet senders and receivers. Accordingly, a personal computer or the like that is currently popular can be used as it is, and broadband communication using a plurality of links can be smoothly provided.

  The main feature of this embodiment is that the link with the earliest expected reception time of the packet between the devices that terminate the link is selected as the packet destination link. As a result, even when the link quality changes, it is possible to improve communication efficiency (broadband and high speed) by performing appropriate packet distribution.

  Hereinafter, an embodiment of a network system to which the present invention is applied will be described in detail with reference to the drawings. First, the configuration of the network system of this embodiment will be described with reference to the drawings.

  FIG. 1 is a general configuration example of the present embodiment. Each device and each terminal in FIG. 1 includes a memory serving as storage means used when performing arithmetic processing, an arithmetic processing device that performs the arithmetic processing, and a network interface (hereinafter simply referred to as an interface). Configured as a computer. The memory is constituted by a RAM (Random Access Memory) or the like. Arithmetic processing is realized by an arithmetic processing unit configured by a CPU (Central Processing Unit) executing a program on a memory.

  The transmission-side distribution device 1 includes an interface 104 and can communicate with the transmission terminal 11 via the network 21. Similarly, the receiving side distribution device 2 includes an interface 204 and can communicate with the receiving terminal 12 via the network 22. The transmission-side distribution device 1 may have the configuration of the reception-side distribution device 2, and the reception-side distribution device 2 may have the configuration of the transmission-side distribution device 1. Thereby, communication in both directions is possible in transmission and reception.

  The interface 101 of the transmission-side distribution device 1 and the interface 201 of the reception-side distribution device 2 can communicate with each other via the network 51, and are connected by a virtual tunnel (link 61) in the network layer as a link. ing. The network 51 is a wired network or a network including a wireless network such as a wireless local area network (LAN) or a mobile phone network.

  The link 61 is, for example, an IPinIP tunnel, an IPsec tunnel, a MobileIP tunnel, or the like. The interface 102, the interface 202, and the network 52, and the interface 103, the interface 203, and the network 53 are the same as the interface 101, the interface 201, and the network 51, respectively, and are connected by a link 62 and a link 63, respectively.

  In addition, as shown in FIG. 2, as one configuration for implementing the modification, the terminal itself may have a function of a sorting device. When the transmission terminal 11 is a transmission-side distribution device 1p that includes the functions of the transmission-side distribution device 1, a packet whose transmission source is the transmission-side distribution device 1p and whose destination is the reception terminal 12 is a transmission-side distribution device. 1p is generated and transmitted to the receiving terminal 12.

  Further, when the transmission-side distribution device 1p transmits a packet to the reception-side distribution device 2, the transmission-side distribution device 1p sends the packet to any route by referring to the header information (application identifier) of the packet. It is good also as deciding whether to transmit through.

  As shown in FIG. 3, there is a case where the sorting apparatus has a redundant configuration as another configuration of the modified implementation. Instead of the transmission-side distribution device 1 in FIG. 1, a transmission-side normal distribution device 1a and a transmission-side sub-distribution device 1b are provided. Similarly, instead of the reception side distribution device 2 of FIG. 1, a reception side normal distribution device 2a and a reception side sub distribution device 2b are provided.

  The transmission-side normal distribution device 1a and the transmission-side sub-distribution device 1b periodically provide link quality information such as the required time and reference transmission interval of the link 60a, the link 60ab, the link 601, the link 60ba and the link 60b, and the link 601, respectively. To measure. Via the link 601, the sending-side normal distribution device 1a and the sending-side sub-distributing device 1b exchange quality information of the link 60a, the link 60ab, the link 60ba, and the link 60b, and the sending-side normal distribution device 1a and Always check whether the sending side sub-distribution device 1b is operating normally.

  When receiving the packet from the transmission terminal 11 whose destination is the reception terminal 12, the transmission-side normal distribution apparatus 1a includes the link 60a, the link 60ab, the link 60ba via the link 601, and the link 60b via the link 601. Among the street links, the packet is transmitted to the link having the earliest expected reception time.

  The same applies when the sending side sub-distribution device 1b receives the packet. By adding a routing header or source routing option to the packet, the packet is forcibly passed through the link 601. It should be noted that the transmission-side normal distribution device 1a and the transmission-side sub-distribution device 1b give priority as a default router to the Router Advertisement broadcast to the network 21 by the transmission-side normal distribution device 1a and the transmission-side sub-distribution device 1b. (See "Draves, R. Hinden," Default Router Preferences, More-Specific Routes, and Load Sharing ", draft-ietf-ipv6-router-selection-02.txt, 2002.6"). As a result, when the transmission terminal 11 transmits a packet to the reception terminal 12, the transmission terminal 11 determines whether to transmit the packet to the transmission-side normal distribution device 1a or the transmission-side secondary distribution device 1b.

  The three system configuration examples have been described above with reference to FIGS. Hereinafter, in order to simplify the description, the system of FIG. 1 is assumed. However, the following description can be easily applied to the system configuration example of FIG. 2 or FIG.

  FIG. 4 shows an internal configuration of the transmission-side distribution device 1. The transmission-side distribution apparatus 1 includes a distribution processing unit 111, a link monitoring unit 112, a tunneling processing unit 113, an alignment processing unit 114, and a retransmission processing unit 115 in addition to the above-described interfaces. The transmission side distribution apparatus 1 is located between the communication paths of the transmission terminal 11 and the reception terminal 12, and is connected to the upstream side (transmission terminal 11 side).

  FIG. 5 shows an internal configuration of the receiving-side distribution device 2. The receiving-side distribution device 2 includes a distribution processing unit 211, a link monitoring unit 212, a tunneling processing unit 213, an alignment processing unit 214, and a retransmission processing unit 215 in addition to the above-described interfaces. In addition, the function of the component of the same name in the transmission side distribution apparatus 1 and the reception side distribution apparatus 2 is the same. The receiving side distribution device 2 is located between the communication paths of the transmitting terminal 11 and the receiving terminal 12, and is connected to the downstream side (receiving terminal 12 side).

  Hereinafter, each parameter used in order for the transmission side distribution apparatus 1 and the reception side distribution apparatus 2 to operate | move is demonstrated. Thereby, each component of the transmission side distribution apparatus 1 and the reception side distribution apparatus 2 becomes clear.

The time required for the link measured by the link monitoring unit 112 is the time required for one-way communication (one-way delay) for a packet flowing on the link, and is represented by a function τ. For example, the link 61 at time t _1, link 62, the duration of the link 63, respectively _{τ1 [t 1], τ2 [} t 1], the τ3 [t _1]. Since the communication quality of the link varies greatly depending on usage conditions and noise, the value of the function τ also changes greatly with time. The link monitoring unit 112 constantly confirms the communication quality of each link and observes the required time τ. In addition to the packet communication time, the required time may include a preparation time (such as a transmission waiting time in the buffer) for the packet to communicate.

FIG. 6 shows a method of measuring the required time τ1 by paying attention to the link 61. When the receiving distributing device 2 via the link 61 receives the packet A1, and the reception time t _2, the by obtaining the difference between the transmission time information t ₁ included in the packet, the link 61 The required time τ1 [t ₃ ] = t ₂ −t ₁ is calculated. Similarly, the required time τ1 [t ₆ ] = t ₅ −t ₄ . The required time τ1 [t ₆ ] may be an average of (t ₅ -t ₄ ) and (t ₂ -t ₁ ). Similar to the link 61, the required time τ is measured for the other links. Note that the header of an arbitrary packet transmitted from the transmission-side distribution device 1 to the link 61 to the link 63 includes time information (time stamp) at which the packet is transmitted from the transmission-side distribution device 1.

  Here, the time information used for calculating the required time is recorded by a clock provided in the distribution device, but the clocks of the transmission-side distribution device 1 and the reception-side distribution device 2 do not have to be synchronized. . This is because the required time is a value used to determine the link having the earliest packet arrival time among the links 61 to 63, and a relative difference regarding the links 61 to 63 can be obtained. It is enough if possible. Therefore, the deviation of the internal clock (clock) between the transmission-side distribution device 1 and the reception-side distribution device 2 is equally included in the required time of the links 61 to 63, and is a meaningless value when calculating the difference between them. Become.

The transmission interval of packets actually transmitted from the transmission-side distribution device 1 via the tunneling processing unit 113 is expressed by a function Δ _snd . For example, the transmission intervals of the link 61, the link 62, and the link 63 at time t ₄ are Δ _snd 1 [t ₄ ], Δ _snd 2 [t ₄ ], and Δ _snd 3 [t ₄ ], respectively. In the following, the expression “at time t” means the latest information that the transmission-side distribution apparatus 1 knows at time t.

The reception interval of packets actually received by the receiving side distribution device 2 via the tunneling processing unit 213 is expressed by a function _Δrcv . For example, the reception intervals of the link 61, the link 62, and the link 63 at time t ₆ are Δ _rcv 1 [t ₆ ], Δ _rcv 2 [t ₆ ], and Δ _rcv 3 [t ₆ ], respectively.

Reference transmission interval of a packet to be transmitted from the transmitting side sorting apparatus 1 via the tunneling processor 113, a transmission interval that is suitable for the link to be transmitted is represented by a function delta _opt. For example, the reference transmission intervals Δ _opt of the link 61, the link 62, and the link 63 at time t ₁ are Δ _opt1 [t ₁ ], Δ _opt2 [t ₁ ], and Δ _opt3 [t ₁ ], respectively.

Here, the reference transmission interval Δ _opt is a time interval converted to a time dimension by dividing the available bandwidth B by the packet length, for example. The usable bandwidth B refers to time interval conversion of a value obtained by subtracting the background traffic already flowing from the amount of data per unit time that can be transmitted in a state where no other traffic is flowing. . In the mathematical definition, assuming that the unit time width is τ, the maximum transferable amount of IP user data per τ is the link bandwidth C, and the queue length is 0 within the time interval (t−τ, t]. The available bandwidth is B = C × a / τ, where the sum of time is a (references “Masato Tsuru and Yuji Oie,“ The Latest Trend of Measurement Technology in Internet Quality Control ”, IEICE Network System (NS ) Technical Report of the Study Group, November 2003 ”).

The link monitoring unit 112 and the link monitoring unit 212 are mainly passive in the transmission / reception status (transmission interval Δ _snd and reception interval Δ _rcv ) of an arbitrary packet transmitted from the transmission-side distribution device 1 to the reception-side distribution device 2. Observe and measure (passively). The transmission / reception state is measured based on the transmission time from the transmission-side distribution device 1 attached to the header of the packet transmitted by the transmission-side distribution device 1 and the reception time of the reception-side distribution device 2.

A method in which the link monitoring unit 112 or the link monitoring unit 212 calculates the reference transmission interval Δ _opt from the measured transmission / reception status will be described below. Calculation of the reference transmission interval delta _opt is realized by already updated the calculated reference transmission interval delta _opt at any time in real time.

FIG. 7A is a graph showing a general correlation between the transmission interval Δ _snd and the reception interval Δ _rcv . This graph is divided into two regions with a predetermined value a as a boundary. The predetermined value a is an ideal value of the reference transmission interval delta _opt, calculated as closer to the reference transmission interval delta _opt to a predetermined value a or less.

First, since Δ _rcv = a in the first region (0 ≦ Δ _snd <a), Δ _snd <Δ _rcv is established. On the other hand, Δ _snd = Δ _rcv is established in the second region (a ≦ Δ _snd ) (Δ _{rcv ≈Δ snd} may be regarded as Δ _snd = Δ _rcv ). Therefore, by comparing the transmission interval Δ _snd and the reception interval Δ _rcv , it is determined whether it belongs to the first region or the second region.

First, the first area shows a state where there is no margin in communication resources. In other words, even if the transmission interval Δ _snd is reduced, the event that the reception interval Δ _rcv is constant is because the bottleneck exists somewhere in the communication line or communication device, so whether the packet is buffered during communication, It is thought that a loss has occurred. Therefore, to be larger than the current value of the reference transmission interval delta _opt in the first region, the reference transmission interval delta _opt approaches a predetermined value a. Note that the value of the updated reference transmission interval delta _opt is, delta may be used as the a is a value _rcv, it may be larger than the value before the update.

Next, the second area shows a state where there is a margin in communication resources. That is, by the amount of reduced transmission interval delta _snd, an event that also small reception interval delta _rcv is believed packets are flowing smoothly the communication line and the communication device. Therefore, to be smaller than the current value of the reference transmission interval delta _opt in the second region, the reference transmission interval delta _opt approaches a predetermined value a. Note that the updated value of the reference transmission interval Δ _opt may be a value smaller than the value of Δ _snd .

  FIG. 7B is a graph showing that the predetermined value is changed from a to a ′ in the graph of FIG. This means that the time interval value at which packets can be transmitted has decreased, and the bandwidth that can be used for communication has increased.

The value of the reference transmission interval delta _opt before update is a predetermined value a, in FIG. 7 (b), the the predetermined value a belongs to the second region. Therefore, the new reference transmission interval Δ _opt approaches the predetermined value a ′ by setting a value (Δ _opt −δ) smaller than the predetermined value a. In this way, the calculation for bringing the reference transmission interval _Δopt closer to the constantly changing predetermined value is repeated.

Note that the calculated reference transmission interval Δ _opt may be reflected in the future transmission interval Δ _snd . Specifically, the transmission interval Δ _snd is set to α ≦ Δ _snd ≦ Δ _opt . α is a lower limit value of an interval that can be transmitted in an interface that transmits a packet. That is, if δ is a constant, Δ _snd is defined by the following equation.
Δ _snd = t ₂ −t ₁ = t ₃ −t ₂ = t ₄ −t ₃ = t ₆ −t ₅ ≡Δ _opt −δ
Then, the packet to the transmission destination of the link transmitting side sorting apparatus 1, after the waiting transmission only reference transmission interval Δ _opt1 [t _3] at time t _3, time _{t 5 = t 3 + Δ1 [} t 3] Send. Thereby, packet loss can be reduced by limiting the amount of communication to an amount suitable for the capability of the communication resource, and highly reliable communication can be realized.

On the other hand, the calculated reference transmission interval Δ _opt may not be reflected in the future transmission interval Δ _snd . Specifically, the transmission-side distribution device 1 sends a packet to the link 61 without waiting for transmission at time t ₃ . This makes it possible to transmit interval delta _snd surplus is reduced communication resource does not belong to the second region, using communication resources efficiently. Further, by not reflecting the reference transmission interval Δ _opt in the transmission interval Δ _snd , the device configuration of the transmission-side distribution device 1 can be simplified.

The above calculation of the reference transmission interval Δ _opt may be performed by either or both of the transmission-side distribution device 1 and the reception-side distribution device 2. The calculation method in the transmission side distribution apparatus 1 is as follows. The reception side distribution apparatus 2 creates a report packet including information on the reception times t ₃ and t _4, and transmits the report packet to the transmission side distribution apparatus 1. it is to be realized by the sending sorter 1 is based on the value of t ₁ ~t _4, to calculate the reference transmission interval update. Alternatively, the calculation method in the receiving side allocating device 2 is that the receiving side allocating device 2 calculates a reference transmission interval based on the values of t ₁ to t ₄ and creates a report packet including the result, By transmitting the report packet to the transmission-side distribution device 1, the transmission-side distribution device 1 updates the reference transmission interval.

The packet to be transmitted by the transmission interval delta _snd is may be used as the data packets transmitted from the transmitting terminal 11 to the receiving terminal 12, when there is room in the transmission interval delta _snd the generated measurement packet instead of the data packet May be transmitted.

There are two calculation methods for the expected reception time of the packet calculated by the link monitoring unit 112. The first calculation method uses the required time τ. For example, a packet transmitted from the link 61 at the transmission time t ₁ has an expected reception time (t ₁ + τ 1 [t ₁ ]) to the receiving-side distribution device 2. )

The second calculation method of the expected packet reception time uses the reference transmission interval Δ _opt and the reception time t ₂ of the packet transmitted immediately before the packet to be transmitted this time. For example, a packet transmitted from the link 61 at the transmission time t ₃ has an expected reception time of (t ₂ + Δ _opt [t ₃ ]).

Note that, as shown in FIG. 8, when the first calculation method and the second calculation method are used in combination, since the parameters used are different, the value of the expected reception time of the calculated packet is often different. In that case, it is desirable to use a calculation result with a delayed expected reception time. For example, the expected reception time of the result of the second calculation method (t ₆ = t ₂ + _Δopt1 [t ₃ ]) is greater than the result of the first calculation method (t ₄ = t ₃ + τ1 [t ₃ ]). Is slow. Therefore, the expected reception time is t ₆ instead of t ₄ .

  Next, the operation of transmitting a packet received from the transmission terminal 11 to the reception side distribution device 2 with the transmission side distribution device 1 as the main operation will be described with reference to the flowchart of FIG. This operation is characterized in that a packet transmitted from the transmission terminal 11 to the reception terminal 12 is distributed to a plurality of links to realize a wider band and higher speed.

The transmission-side distribution device 1 receives the packet A having the transmission terminal 11 as the transmission source and the reception terminal 12 as the destination at time t ₁ via the interface 104 (S102). Next, the link monitoring unit 112 obtains link communication quality (required time τ and reference transmission interval Δ _opt ) at time t ₁ (S104).

Then, the link monitoring unit 112 calculates an expected reception time of each link, and the distribution processing unit 111 determines a link that is a transmission destination of the packet A based on the expected reception time (S106). Expected reception time, of the second calculation method using the first calculation method or reference transmission interval delta _opt to use a required time tau, at least one calculation method is performed. For example, the link monitoring unit 112 sets the expected reception time t ₂ of the packet A to t ₂ = t ₁ + τ1 [t ₁ ] by the first calculation method. When the estimated reception time of each link is calculated, the distribution processing unit 111 selects the link corresponding to the earliest time as the transmission destination link. In the following description, it is assumed that the link 61 is selected.

  Next, as shown in FIG. 10, the tunneling processing unit 113 adds a header indicating a link that is a virtual tunnel to the packet A for which the transmission destination link is determined in S106, and then transmits the packet A to the link 61 (S108). ). For example, if the link 61 is an IPinIP tunnel, a header having the IP address of the interface 101 as the source address and the destination address as the IP address of the interface 201 is added to the packet A, and then the interface 101 to the interface 101 The data is transferred to 201. As described above, the packet group transmitted from the transmission terminal 11 to the reception terminal 12 is distributed to a plurality of links by the transmission-side distribution device 1 and the reception-side distribution device 2.

  The header to be added includes the time when the packet is transmitted from the transmission-side distribution device 1, the entire sequence number X of the packet sequence received from the interface 104, and the packet transmitted to the link 61. The individual sequence number Y of the column is included as information for control between the sorting apparatuses. The control information is not only described in the header of the packet transmitted by the transmission distribution device 1 but also held for a certain period of time together with the packet in the transmission-side distribution device 1 itself.

  In addition, the entire sequence number X of the header to be added indicates that the receiving-side distribution device 2 transmits packets to the receiving terminal 12 in the order that the transmitting-side distribution device 1 has received from the transmission terminal 11. The main purpose is a sequence number that is common to the links 61 to 63 and given through packets output from the links 61 to 63. On the other hand, the individual sequence number Y is assigned for each of the links 61 to 63 in order to identify a packet that is lost mainly when transferring from the transmission-side distribution device 1 to the reception-side distribution device 2. Sequence number.

  For example, the entire sequence numbers X (X1 to X6) are assigned to the packets A to F received by the transmission-side distribution apparatus 1 from the transmission terminal 11, respectively. When the packet A and the packet D are transferred to the link 61, the individual sequence numbers Y (Y1 and Y2) of the link 61 are given respectively. The same applies to the packet B and packet E transferred to the link 62, and the packet C and packet F transferred to the link 63.

  The operation of transferring the received packet to the receiving terminal 12 with the receiving side distribution device 2 as the main operation will be described with reference to the flowchart of FIG.

  The interface 201 of the receiving side distribution apparatus 2 receives the packet transmitted to the link in S108 (S110).

  As shown in FIG. 11, the retransmission processing unit 215 detects packet loss for each link for the packet received in S110 (S112). Specifically, the retransmission processing unit 215 refers to the individual sequence number Y of the received packet for each link, and identifies a packet lost during transfer in the received link. The retransmission processing unit 215 requests the transmission side distribution apparatus 1 to retransmit a packet lost during transfer.

  For example, it is assumed that the transmission-side distribution device 1 sequentially transmits packets A1 to A4 to the link 61 and assigns individual sequence numbers Y1 to Y4 to the header of each packet. Here, it is assumed that the packet A3 is lost in the link 61 due to problems such as congestion and transmission error. When receiving side packet 2 is received after packet A1 and packet A2, receiving side sorting apparatus 2 operates a timer for waiting for reception of packet A3.

  If the packet A3 can be received before the timer expires, the timer is canceled. If the packet A3 cannot be received before the timer expires, the receiving side distribution device 2 generates a retransmission request packet instructing retransmission of the packet A3 having the individual sequence number Y3, and the transmission side distribution device 1 Send to. The transmission side distribution apparatus 1 that has received the retransmission request packet refers to the control information that has been held, and retransmits the packet A3, which is the individual sequence number Y3, via the link 61 in accordance with the procedure from S102.

  Note that the retransmission processing unit 215 calculates the packet loss rate of each of the links 61 to 63 by the mechanism. The reception-side distribution device 2 generates a report packet for notifying the transmission-side distribution device 1 of the packet loss rate, and transmits the report packet to the transmission-side distribution device 1. The transmission side distribution device 1 that has received the report packet refers to the packet loss rate of each of the links 61 to 63, regards a link with a packet loss rate equal to or higher than a predetermined frequency (exceeding a threshold) as an unstable link, Transfer to the link may be temporarily stopped. Then, the link whose packet loss rate falls below the threshold is regarded as a stable link, and the transfer to the link is resumed.

  As shown in FIG. 12, the alignment processing unit 214 performs alignment processing for each packet for which packet loss has been dealt with in S112, according to the entire sequence number X of the packet (S114). That is, the alignment processing unit 214 refers to the entire sequence number X of the packets, and arranges the packets so that the transmission-side distribution apparatus 1 is in the same order as when received from the transmission terminal 11.

  For example, the transmitting terminal 11 transmits to the receiving terminal 12 in the order of packets A1 to A4, and the receiving side distribution device 2 receives the packets A1 and A2 followed by the packets A4 and A3 in this order. To do. At that time, the receiving side distribution apparatus 2 does not immediately transfer the packet A4 to the receiving terminal 12, but refers to the entire sequence number X described in the header of the packet added by the transmission side distribution apparatus 1, After waiting for a predetermined time until the packet A3 is received, the packet A3 and the packet A4 are sequentially transferred to the receiving terminal 12.

  If the receiving side distribution apparatus 2 cannot receive the packet A3 even after a predetermined time has elapsed, the receiving side distribution apparatus 2 generates a retransmission request packet instructing retransmission of the packet A3, and sends it to the transmission side distribution apparatus 1. Send to. The transmission-side distribution apparatus 1 that has received the retransmission request packet refers to the control information that is held, and retransmits the packet A3 according to the procedure from S104.

  And the receiving side distribution apparatus 2 transfers each packet arranged in S114 to the receiving terminal 12 in order through the interface 204 (S116).

  The present invention described above can be widely modified without departing from the spirit thereof as follows.

  For example, as shown in FIG. 13, the tunneling processing unit 113 and the tunneling processing unit 213 proxy (end) the TCP session between the transmission terminal 11 and the reception terminal 12 when necessary. In this case, the TCP session between the transmission terminal 11 and the reception terminal 12 is a proxy response that the transmission-side distribution device 1 performs TCP control with respect to the transmission terminal 11 and the reception-side distribution device 2 with respect to the reception terminal 12 as a proxy response. As a result, the TCP session between the transmission terminal 11 and the transmission-side distribution device 1 and the reception-side distribution device 2 and the reception terminal 12 can be performed without requiring any additional functions at the transmission terminal 11 and the reception terminal 12. And a TCP session. Then, the transmission terminal 11 and the reception terminal 12 can recognize each other as if they have directly established a TCP session with the partner terminal. In addition to the two TCP sessions, a third TCP session may be created between the transmission-side distribution device 1 and the reception-side distribution device 2.

  As a result, for example, when the links 61 to 63 have network characteristics with a larger delay than the networks 21 and 22, between the transmission terminal 11 and the transmission-side distribution device 1 and between the reception-side distribution device 2 and the reception terminal By setting the TCP parameters between 12 to values suitable for the characteristics of the network 21 and the network 22, respectively, it is possible to improve the throughput between the transmission terminal 11 and the reception terminal 12.

  Further, the transmission terminal 11 may select whether to execute the packet loss detection process (S112) by the retransmission processing unit 215 or the packet alignment process (S114) by the alignment processing unit 214. For example, when UDP (User Datagram Protocol) is specified in the header of a packet transmitted by the transmission terminal 11, the execution of the packet loss detection process (S112) and the packet alignment process (S114) is omitted.

It is a block diagram which shows the network system regarding one Embodiment of this invention. It is a block diagram which shows the network system by which the transmission terminal regarding one Embodiment of this invention was included by the transmission side distribution apparatus. It is a block diagram which shows the network system with which the transmission side distribution apparatus and the reception side distribution apparatus regarding one Embodiment of this invention were made redundant. It is a block diagram which shows the transmission side distribution apparatus regarding one Embodiment of this invention. It is a block diagram which shows the receiving side distribution apparatus regarding one Embodiment of this invention. It is explanatory drawing which shows the required time regarding one Embodiment of this invention, and each time interval. It is explanatory drawing which shows calculation of the reference | standard transmission interval regarding one Embodiment of this invention. It is explanatory drawing which shows that the estimated reception time of the packet regarding one Embodiment of this invention is calculated by two types. It is a flowchart which shows the packet transmission process by the network system regarding one Embodiment of this invention. It is explanatory drawing which shows two types of sequence numbers regarding one Embodiment of this invention. It is explanatory drawing which shows the countermeasure to the packet loss regarding one Embodiment of this invention. It is explanatory drawing which shows the response | compatibility to the order change of the packet regarding one Embodiment of this invention. It is a block diagram which shows the network system by which the TCP connection regarding one Embodiment of this invention was terminated.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Transmission terminal 12 Reception terminal 1, 11p Transmission side distribution apparatus 2 Reception side distribution apparatus 1a Transmission side normal distribution apparatus 1b Transmission side sub distribution apparatus 2a Reception side normal distribution apparatus 2b Reception side sub distribution apparatus 21, 22, 51-53 network 61-63 link 101-104, 201-204 interface 111, 211 distribution processing unit 112, 212 link monitoring unit 113, 213 tunneling processing unit 114, 214 alignment processing unit 115, 215 retransmission processing unit

Claims (17)

A packet transmitted from the transmission terminal and arriving at the reception terminal from the transmission-side distribution device via the reception-side distribution device passes through a plurality of links between the transmission-side distribution device and the reception-side distribution device. A network system that flows on multiple links
The transmission-side distribution device is
An interface for receiving a packet transmitted from the transmitting terminal;
For each link constituting the multilink, a link monitoring unit that calculates an expected reception time of the packet to the receiving distribution device based on the communication quality of the monitored link;
For each link constituting the multilink, a distribution processing unit that determines a link with the earliest expected reception time as a destination link;
Possess a tunneling processor to transmit the packet to the destination link,
The link monitoring unit calculates a reference transmission interval of a link from a transmission interval of packets transmitted by the transmission-side distribution device and a reception interval of packets received by the reception-side distribution device, and receives a packet transmitted immediately before A network system characterized in that a sum of a time and a reference transmission interval of the link is the expected reception time . The tunneling processing unit transmits each packet with an individual sequence number for identifying each packet to be transmitted for each link,
The receiving-side distribution device has a retransmission processing unit that detects a packet loss based on the individual sequence number of the received packet and makes a retransmission request for a packet that could not be received due to the packet loss,
The network system according to claim 1, wherein the transmission side distribution apparatus receives a packet retransmission request and retransmits the corresponding packet. The tunneling processing unit sends each packet with an overall sequence number for identifying each packet to be transmitted for each multilink,
The receiving-side distribution device includes an alignment processing unit that arranges the order of packets based on the entire sequence number of received packets and transmits the packets to the receiving terminal. Network system. The alignment processing unit detects a packet loss based on the entire sequence number when arranging the packets, and performs a retransmission request for a packet that could not be received due to the packet loss,
The network system according to claim 3, wherein the transmission side distribution apparatus receives a packet retransmission request and retransmits the corresponding packet.   The network system according to any one of claims 2 to 4, wherein the transmission-side distribution device temporarily stops communication via a link in which packet loss occurs at a predetermined frequency or more. . The transmission terminal and the transmission-side distribution device are accommodated in the same casing,
The network system according to any one of claims 1 to 5, wherein the distribution processing unit determines a transmission destination link according to an application identifier described in header information of a packet to be transmitted. . Each of the transmission-side distribution device and the reception-side distribution device is configured with redundancy by a plurality of housings,
The link monitoring unit of each housing exchanges information regarding the communication quality of the link with the link monitoring unit of the other housing,
The transmission-side distribution device monitors each other so as to detect a failure between the cases constituting the transmission-side distribution device, and when a predetermined case fails, the other case acts as a proxy for packet communication,
The receiving-side distribution device monitors each other so as to detect a failure between the cases constituting the receiving-side distribution device, and when a predetermined case fails, the other case acts as a proxy for packet communication. The network system according to any one of claims 1 to 6, wherein: For the TCP session between the transmission terminal and the reception terminal, the transmission-side distribution device and the reception-side distribution device include a first TCP session between the transmission terminal and the transmission-side distribution device, and the reception The network system according to any one of claims 1 to 7, wherein a second TCP session is created between a terminal and the receiving-side distribution device. The link monitoring unit
The required time of the link is calculated from the difference between the transmission time of the packet transmitted by the transmission side distribution device and the reception time of the packet received by the reception side distribution device, and the sum of the transmission time and the required time of the link is calculated. The first expected reception time
The reference transmission interval of the link is calculated from the transmission interval of the packet transmitted by the transmission-side distribution device and the reception interval of the packet received by the reception-side distribution device, and the reception time of the packet transmitted immediately before and the link The sum of the reference transmission intervals is the second expected reception time,
The network system according to any one of claims 1 to 8, wherein a later time of the first expected reception time and the second expected reception time is set as the expected reception time of the packet. In the calculation of the reference transmission interval of the link, the link monitoring unit sets the reference transmission interval of the link to a smaller value than the present if the transmission interval and the reception interval are equal, and if the transmission interval is smaller than the reception interval, the link The network transmission system according to any one of claims 1 to 9, wherein the reference transmission interval is updated to a value larger than a current value. The network system according to claim 10 , wherein the tunneling processing unit transmits a packet at a transmission interval equal to or less than a reference transmission interval of the link calculated by the distribution processing unit. The network system according to claim 11 , wherein the tunneling processing unit uses, as a packet to be transmitted, a packet transmitted from the transmission terminal or a measurement packet created by the transmission-side distribution device. The network system according to claim 10 , wherein the tunneling processing unit transmits a packet at a shortest transmission interval that can be transmitted from a link. A packet transmitted from the transmission terminal and arriving at the reception terminal from the transmission-side distribution device via the reception-side distribution device passes through a plurality of links between the transmission-side distribution device and the reception-side distribution device. The transmission-side distribution device used in a network system that flows on bundled multilinks,
An interface for receiving a packet transmitted from the transmitting terminal;
For each link constituting the multilink, a link monitoring unit that calculates an expected reception time of the packet to the receiving distribution device based on the communication quality of the monitored link;
For each link constituting the multilink, a distribution processing unit that determines a link with the earliest expected reception time as a destination link;
Possess a tunneling processor to transmit the packet to the destination link,
The link monitoring unit calculates a reference transmission interval of a link from a transmission interval of packets transmitted by the transmission-side distribution device and a reception interval of packets received by the reception-side distribution device, and receives a packet transmitted immediately before The transmission side distribution apparatus characterized in that the sum of the time and the reference transmission interval of the link is the expected reception time . The transmission-side distribution device according to claim 14 , wherein the transmission-side distribution device has a configuration of the reception-side distribution device. A packet transmitted from the transmission terminal and arriving at the reception terminal from the transmission-side distribution device via the reception-side distribution device passes through a plurality of links between the transmission-side distribution device and the reception-side distribution device. A packet communication method by a network system that flows on a bundled multi-link,
The transmission-side distribution device is
Receiving a packet transmitted from the transmitting terminal;
For each link constituting the multi-link, a procedure for calculating an expected reception time of the packet to the receiving-side distribution device based on the communication quality of the monitored link;
A procedure for determining a link having the earliest expected reception time as a destination link for each link constituting the multilink;
Perform steps to send packets to the destination link ,
The procedure for calculating the expected reception time is to calculate a reference transmission interval of a link from a transmission interval of packets transmitted by the transmission-side distribution device and a reception interval of packets received by the reception-side distribution device, and transmit immediately before A packet communication method characterized in that a sum of a received time of a received packet and a reference transmission interval of the link is set as the expected reception time . The packet communication method according to claim 16, the packet communication program to be executed by the a transmitting side sorter computer.

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