JP2016165072A - Switching system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system capable of reducing a facility cost for switching a communication channel.SOLUTION: A switching device 116 includes a transmission unit 401, a reception unit 402, an evaluation unit 403, and a switching unit 404. The evaluation unit evaluates communication performance of a radio communication channel on the basis of information on reception of a response telegraphic message returned from a response device in response to a response request telegraphic message transmitted to the response device through the radio communication channel. The switching unit, when the evaluation unit's evaluation shows the response has not been received in response to the response request or a time until the response has been received after the transmission of the response request is not within a predetermined time, switches a channel used for a terminal's communication with a server to a communication channel differing from the radio communication channel.SELECTED DRAWING: Figure 4A

Description

  The present invention relates to a switching system for switching a plurality of communication lines.

  Conventionally, in order to ensure high reliability, a technique using a plurality of communication lines is known (see, for example, Patent Document 1). In Patent Document 1, the optical transmission line is duplicated to be redundant, and high reliability is ensured.

  On the other hand, in recent years, a technique of a wireless communication line typified by a mobile phone has been developed (for example, see Patent Document 2), and a communication speed equivalent to that of an optical transmission path has been obtained. In particular, standards for mobile communication systems such as LTE (Long Term Evolution) and LTE-Advanced have been studied for practical use, and high-speed wireless communication can be easily used. In addition to pure carriers that own lines, virtual mobile carriers that provide services by borrowing lines from pure carriers have entered the market as mobile carriers, and wireless communication is used at a lower cost. It is becoming possible.

JP 2014-107823 A Japanese Patent Laying-Open No. 2015-23303

  Communication over a wireless communication line falls into an unstable situation, and the communication performance of the communication line may be greatly impaired temporarily. For this reason, it is conceivable to switch to wired communication in case the communication performance in wireless communication is impaired. However, in the present day when wireless communication can be used easily and inexpensively, there is a problem that the cost of equipment for switching a wired communication line should be reduced. In addition, there is a problem that it is not clear what criteria should be used to switch to wired communication and what procedure should be switched to wired communication.

  Therefore, in the following, disclosure will be made with one of the purposes of solving these problems.

  As one embodiment of the present invention, a switching system for switching a communication line used by a terminal for communication with a server is provided. The switching system includes an evaluation unit and a switching unit. The evaluation unit communicates the wireless communication line based on information related to reception of a response message transmitted from the response device in response to transmission of a response request message transmitted to the response device via the wireless communication line. Evaluate performance. If the communication performance of the wireless communication line does not satisfy the first condition based on the evaluation by the evaluation unit, the switching unit switches the line used by the terminal for communication with the server to a communication line different from the wireless communication line.

  According to the present invention, the cost of equipment for switching communication lines can be reduced.

1 is a functional block diagram of a communication system according to an embodiment of the present invention. (A) An example figure of routing information in a communication system concerning one embodiment of the present invention; (B) An example figure of routing information in a communication system concerning one embodiment of the present invention. (A) Sequence diagram at the time of communication in the system according to the embodiment of the present invention; (B) Sequence diagram at the time of communication in the system according to the embodiment of the sound of the present invention. Functional block diagram of a switching device used in a system according to an embodiment of the present invention The functional block diagram which comprised the switching apparatus used for the system which concerns on one Embodiment of this invention as a system The flowchart of the process by the switching apparatus used for the system which concerns on one Embodiment of this invention. The flowchart of the process by the switching apparatus used for the system which concerns on one Embodiment of this invention. 1 is a functional block diagram of a communication system according to an embodiment of the present invention. An example figure of routing information in a communications system concerning one embodiment of the present invention The flowchart of the process by the switching apparatus used for the system which concerns on one Embodiment of this invention. The flowchart of the process by the router used for the system which concerns on one Embodiment of this invention

  Hereinafter, the form for implementing this invention is demonstrated by several embodiment. The present invention is not limited to a plurality of embodiments described below, and can be implemented with various modifications.

(Embodiment 1)
FIG. 1 shows a functional block diagram of a communication system according to Embodiment 1 of the present invention. As illustrated in FIG. 1, the communication system 100 includes a terminal system 101 and a server system 102. The terminal system 101 and the server system 102 can communicate with each other via the access point 103.

  When the terminal system 101 and the server system 102 communicate with each other, the terminal system 101 and the server system 102 can first use the wireless communication line 105 via the base station 104, and further, the base station 104 and the access point Communication can be performed via the access point 103 using a communication line connecting to the mobile phone 103. As the radio communication line 105, a mobile radio communication line can be used. A typical example is a communication line provided for mobile phone communication. Further, as a communication line between the base station 104 and the access point 103, for example, a communication line using a dedicated line can be used. Further, another access point exists between the base station 104 and the access point 103, and a mobile communication provider that provides a service of the wireless communication line 105 is used between the base station and another access point. A line using a dedicated line can be used between another access point and the access point 103 using a line. Thus, the communication line through which the terminal system 101 and the server system 102 communicate via the base station 104 and the access point 103 is referred to as a first communication line.

  When the terminal system 101 and the server system 102 communicate with each other, the terminal system 101 and the server system 102 can use the communication line 106 second. In this case, the communication line 106 is a communication line different from the wireless communication line 105. For example, wired communication using an optical fiber or a copper wire cable, a typical example is a wired line to which a fixed telephone is connected, and more specifically, an ISDN (Integrated Services Digital Network) line. ISDN provides a service with a maximum communication speed of 64 Kbps per data channel of a basic rate interface (Basic Rate Interface), and is generally lower than the communication speed of a mobile radio communication line. However, the communication speed of ISDN is virtually guaranteed, is reliable, and is cheaper than installing a dedicated line. The communication line 106 may be referred to as a second communication line. The communication line 106 may be a wireless communication line provided by a provider different from the provider that provides the service of the wireless communication line 105. For example, although the communication speed is inferior to the wireless communication line 105, it may be a wireless communication line provided by a provider that provides communication costs at a low cost.

  One characteristic point of the first communication line is that the terminal system 101 includes a terminal device (or a terminal) that uses the wireless communication line 105. One of the characteristic points of the second communication line is that the terminal system 101 is equipped with a terminal device that uses the communication line 106, which is a communication line different from the first communication line. Is a point.

  In FIG. 1, the terminal system 101 includes one or a plurality of terminals 111, 112, 113, a LAN switch 114, a first router 115, a second router 117, and a switching device 116.

  The one or more terminals 111, 112, and 113 are devices for communicating with the server system 102. For example, a surveillance camera that transmits a captured image to the server system 102, a POS (Point of Sale system) terminal that transmits sales data to the server system 102 and is provided in a store, or a financial institution such as a bank It communicates with the server system 102 and transmits weather data such as weather to the server system 102, such as ATM (Automatic Teller Machine) and CD (Cash Dispenser), which are provided in branch offices, convenience stores or unmanned stores of financial institutions. It can be a weather station or the like.

  The LAN switch 114 is a so-called repeater, which relays communication data (message or packet) transmitted from one or a plurality of terminals 111, 112, 113 to the first router 115, the second router 117, The second router 117 relays communication data transmitted to a plurality of terminals 111, 112, 113 to one or a plurality of terminals 111, 112, 113. Further, communication data is relayed between a plurality of terminals 111, 112, and 113. A specific example of the LAN switch 114 is an L2 switch.

  The first router 115 has at least A1 and A2 as interfaces, and transmits communication data received by the respective interfaces from an appropriate interface according to the destination of the communication data. In order to transmit from an appropriate interface according to Destination, the routing information stored in the routing table is usually referred to. In the present embodiment, in normal times, the routing information of the first router 115 basically transmits the communication data received by A1 from A2, and transmits the communication data received by A2 from A1. Is set to A 1 is connected to the LAN switch 114, and A 2 is connected to the wireless communication line 105. As a result, during normal times, the terminals 111, 112, 113 and the server system 102 can communicate using the wireless communication line 105. However, as will be described later, when the switching device 116 detects that the communication performance of the wireless communication line 105 has deteriorated, the routing information of the first router 115 changes the communication data received by A1 from the A1 to the second router. To be sent to. Thereby, the terminals 111, 112, 113 and the server system 102 can communicate with each other via the second router 117 using the communication line 106. Note that the deterioration in communication performance includes a state where a communication line has failed and communication cannot be performed using the communication line.

  Note that the first router 115 communicates with the base station 104 through the wireless communication line 105 when transmitting communication data from the A2 in a state where communication with the base station 104 through the wireless communication line 105 has not been established. After establishing, communication data is transmitted from A2. For example, when a network address such as an IP address is not set in A2, communication is performed with a predetermined protocol with the base station 104 or the like, and the network address set in A2 is set.

  The switching device 116 is a device for switching a line used for the terminals 111, 112, and 113 to communicate with the server of the server system 102. The switching device 116 performs processing for switching the line used by the terminals 111, 112, and 113 to communicate with the server of the server system 102 to either the wireless communication line 105 or the communication line 106. Specifically, communication is performed with the response device 121 via the wireless communication line 105, the communication performance of the wireless communication line 105 is evaluated, and switching is performed according to the evaluation result. In FIG. 1, the switching device 116 is directly connected to the first router 115, but may be connected to the LAN switch 114. Further, communication with the response device 121 may be performed using the wireless communication line 105 without going through the first router 115. Details will be described later.

  The second router 117 has A3 and A4 as interfaces, and transmits communication data received by each interface from an appropriate interface according to the destination of the communication data. The routing information of the second router 117 is basically set so that communication data received by A3 is transmitted from A4, and communication data received by A4 is transmitted to A3. A 3 is connected to the LAN switch 114, and A 4 is connected to the communication line 106. Accordingly, when the switching device 116 detects that the communication performance of the wireless communication line 105 is deteriorated, the first router 115 transmits the communication data received by A1 to A3. The second router 117 transmits communication data received by A3 from A4, and communication data received by A4 is transmitted from A3. As a result, the terminals 111, 112, 113 and the server system 102 can communicate with each other using the communication line 106.

  Note that the second router 117 transmits communication data from A4 after establishing communication through the communication line 106 when transmitting communication data from the A4 in a state where communication through the communication line 106 is not established. . For example, if the communication line 106 is a telephone line such as ISDN, dial up with a modem connected to A4, establish communication with the access point 103, set a network address in A4, and communicate from A4 Send data.

  It is desirable that the network address set for A2 and the network address set for A4 are different. If the network address set in A2 is the same as the network address set in A4, when transmitting communication data addressed to the terminal system 101 from the server system 102, the access point 103 or the like It is necessary to monitor the communication performance of the communication line 105 and change the routing information stored in the access point 103 or the like. In other words, the access point 103 also needs to monitor the communication performance of the wireless communication line 105. If there is a discrepancy between the result of monitoring and the result of monitoring communication performance by the switching device 116, the communication between the terminal system 101 and the server system 102 may become impossible. However, if the network address set in A2 is different from the network address set in A4, there is no need to change the routing information stored in the access point 103 or the like. It is not necessary to monitor the communication performance of 105. Thereby, the communication system 100 having high reliability can be realized at a lower cost.

  The access point 103 relays communication between the terminal system 101 and the server system 102. The access point 103 includes interfaces B2 and B3 on the terminal system 101 side, and transmits and receives communication data to and from the first router 115 and the second router 117, respectively. The access point 103 includes an interface B4 on the server system 102 side, and transmits / receives communication data to / from the interface B5 of the server system 102. Although the access point 103 is shown in FIG. 1 as being a single device, it may be composed of a plurality of devices. For example, different devices may have interfaces B2 and B3, respectively. Good. Further, the interface B4 may actually be composed of a plurality of interfaces.

  When receiving the communication data (referred to as response request communication data) transmitted from the switching device 116, the response device 121 returns response communication data to the switching device. The response device 121 includes an interface B1. In FIG. 1, B <b> 1 is connected between the base station 104 and the access point 103. However, the present invention is not limited to this, and the response device 121 may be directly connected to the base station 104 or the access point 103 or may be connected to the server system 102. One of the features of the response device 121 is that it communicates with the switching device 116 via the wireless communication line 105. Thereby, the communication performance of the wireless communication line 105 can be evaluated.

  The server system 102 is a system composed of one or a plurality of servers. The terminals 111, 112, and 113 can communicate with one or a plurality of servers constituting the server system using either the wireless communication line 105 or the communication line 106 as described below.

  2A and 2B show examples of routing information.

  2A shows the routing information of the terminals 111, 112, and 113, the first router 115, and the second router 117 when the terminal system 101 and the server system 102 communicate via the wireless communication line 105. FIG. Show. The routing information of the terminals 111, 112, and 113 is “* via A1”. “*” Is a wildcard that matches any network address, and “A1” is the interface A 1 of the first router 115. Therefore, “* via A1” indicates that communication data addressed to any network address is transmitted to A1. That is, A1 is a default gateway for the terminals 11, 112, and 113.

  The routing information of the first router 115 is “B5 via A2” and “B1 via A2”. Thus, the communication data destined for B5 of the server system 102 is transmitted from A2, and the communication data destined for the response device 121 is also transmitted from A2. Therefore, when the first router 115 receives communication data destined for the server system 102 from the terminals 111, 112, and 113, the first router 115 transmits from A2, and the communication data destined for the response device 121 from the switching device 116 is transmitted. When received, transmission is performed from A2.

  The routing information of the second router 117 is “B5 via A4”. Accordingly, if the second router 117 receives communication data destined for B5 included in the server system 102, transmission is performed from A4. However, when the terminal system 101 and the server system 102 are communicating via the wireless communication line 105, it is preferable that this does not normally occur. For example, when the communication performance of the wireless communication line 105 is good and the communication speed by the wireless communication line 105 is higher than the communication line 106, communication can be performed at a high communication speed.

  In addition, it can be paraphrased that communication performance is favorable or has not deteriorated (not bad) when communication performance satisfies a certain condition. As described below, after the switching device 116 transmits a response request to the response device 121, a response to the response request cannot be received from the response device 121, or even if it can be received, the time required until reception Exceeding a predetermined value can be defined as not satisfying a certain condition. Further, a value determined by each of a plurality of required times from when the switching device 116 sequentially transmits a response request to the response device 121 a plurality of times until a response to the response request is received from the response device 121. It can be defined that a certain condition is not satisfied.

  FIG. 2B shows the routing information of the terminals 111, 112, and 113, the first router 115, and the second router 117 when the terminal system 101 and the server system 102 communicate via the communication line 106. . The routing information of the terminals 111, 112 and 113 and the second router 117 is the same as that in FIG.

  However, the routing information of the first router 115 is “B5 via A2” instead of “B5 via A2” in FIG. Thus, when any of the terminals 111, 112, and 113 transmits communication data addressed to B5 of the server system 102, it is received by A1, and the first router 115 transmits from A1 to A3. When A3 receives communication data destined for B5, it transmits from A4. Therefore, when any of the terminals 111, 112, and 113 transmits communication data addressed to B5 of the server system 102, communication is performed via the communication line 106. However, in FIG. 2B as well, since there is routing information “B1 via A2” as in FIG. 2A, the communication data that the switching device 116 transmits to the response device 121 is still transmitted from A2. The wireless communication line 105 is used and transmitted to the response device 121 (however, when the wireless communication line 105 fails and the wireless communication line 105 becomes unusable, the switching device 116 transmits to the response device 121. Data is lost).

  Therefore, if the communication performance of the wireless communication line 105 is good, the routing information of “B5 via A2” is set in the first router 115, and the communication performance of the wireless communication line 105 may deteriorate or become unusable. For example, the routing information “B5 via A3” is set in the first router 115 instead of the routing information “B5 via A2”. Thereby, even if the communication performance of the wireless communication line 105 deteriorates or becomes unusable, the terminal system 101 and the server system 102 can communicate via the communication line 106.

  Note that the routing information shown in FIGS. 2A and 2B is routing information used when communication data is transmitted from the terminals 111, 112, and 113 toward the server system 102. The server system Routing information used when communication data is transmitted from the terminal 101 to the terminals 111, 112, and 113 is omitted.

  3A and 3B, the routing information of the terminals 111, 112 and 113, the first router 11 and the second router 117 is the information shown in FIGS. 2A and 2B, respectively. The sequence diagram of communication in the case is shown.

  Referring to FIG. 3A, when the switching device 116 transmits a response request to the response device 121 in step S <b> 201, the response emergency is received by the first router 115. In step S <b> 202, the first router 115 transmits a response request to the base station 104 via the wireless communication line 105. In step S <b> 203, a response request is transmitted from the base station 104 to the response device 121.

  In step S204, the response device 121 returns a response to the response request. This response is received by the base station 104. In step S <b> 205, the base station 104 transmits a response to the first router 115 via the wireless communication line 105. In step S <b> 206, the first router 115 transmits a response to the switching device 116. If the switching device 116 can receive the response in step S206 in response to the response request in step S201 within a predetermined time, the switching device 116 determines that the communication performance of the wireless communication line 105 is good. Therefore, the routing information “B5 via A2” is set in the first router 115. This setting can be performed by the switching device 116, for example.

  Therefore, in step S207, if any of the terminals 111, 112, and 113 transmits transmission data that is communication data destined for the server system 102 to the first router 115, in step S208, the first router 115 The transmission data is transmitted to the base station 104 via the wireless communication line 105. In step S <b> 209, the base station 104 transmits transmission data to the server system 102.

  When the server system 102 receives the transmission data, in step S210, the server system 102 transmits communication data, which is reply data to the transmission data, toward the base station 104. When the base station 104 receives the reply data, it transmits it to the first router 115 via the wireless communication line 105 in step S211. When the first router 115 receives the reply data, the first router 115 transmits the reply data to any of the terminals 111, 112, and 113 in step S212.

  On the other hand, FIG. 3B is a sequence diagram when the communication performance of the wireless communication line 105 deteriorates. In step S <b> 213, the switching device 116 transmits a response request to the first router 115. The first router 115 tries to transmit the received request to the base station 104 according to the routing information of “B1 via A2”. However, here, the communication performance of the wireless communication line 105 deteriorates, and the response to the request is not received by the response device 121 or the response from the response device 121 is not received by the switching device 116 within a predetermined time. In the first router 115, routing information “B5 via A3” is set.

  Accordingly, if any of the terminals 111, 112, and 113 transmits transmission data addressed to the server system 102 to the first router 115 in step S214, the first router 115 transmits the transmission data to the second router 117 in step S215. Send to. In step S <b> 216, the second router transmits the transmission data to the server system 102 via the communication line 106.

  When the server system 102 receives the transmission data and transmits the reply data in step S217, it is transmitted to the second router 117 via the communication line 106. The second router 117 transmits the reply data to the first router 115 in step S218, and the first router 115 transmits the reply data to any of the terminals 111, 112, and 113 in step S219 (or the first router 115). (2) The router 117 can also transmit the reply data to the first router 115 without directly transmitting to any of the terminals 111, 112, and 113.)

  If the communication performance of the wireless communication line 105 is improved, it is detected that a response to the request from the switching device 116 can be received from the response device 121 within a predetermined time. Therefore, “B5 via A2” is set in the first router 115 instead of the routing information “B5 via A3”.

  Therefore, the terminals 111, 112, and 113 can communicate with the server of the server system 102 using either the wireless communication line 105 or the communication line 106.

  FIG. 4A shows a functional block diagram of the switching device 116. The switching device 116 includes a transmission unit 401, a reception unit 402, an evaluation unit 403, and a switching unit 404.

  The transmitting unit 401 transmits and transmits communication data for requesting a response (hereinafter may be abbreviated as a request for response) to the response device 121. The response request is transmitted to the response device 121 using the wireless communication line 105. Specifically, the response request may be an ICMP (Internet Control Message Protocol) echo request addressed to the IP address of B1. ICMP is a basic protocol on the Internet, so that any device that can connect to the Internet can perform normal processing. For this reason, it is not necessary to make the response device 121 a special device by making the communication data of the response request based on ICMP.

  The transmitting unit 401 may transmit a plurality of response requests at regular time intervals. For example, a response request is transmitted every 2 seconds. When the communication performance is good, the response request transmission interval is increased, and when the communication performance starts to change from a good state to a bad state, for example, the time from the response request transmission to the response reception The transmission interval may be changed so as to reduce the transmission interval of the response request. As a result, when the communication performance is good, it is possible to prevent the bandwidth of the wireless communication line 105 from being compressed by transmitting and receiving a response request and a response.

  The receiving unit 402 receives communication data of a response to a response request transmitted from the transmitting unit 401 to the response device 121 (hereinafter, may be abbreviated as a response). In FIG. 1, a response to the response request transmitted to the response device 121 is received via the wireless communication line 105. However, at least one of the response request and the response may be transmitted using the wireless communication line 105. For example, a response request is transmitted from the switching device 116 to the response device 121 using the wireless communication line 105, and a response is transmitted from the response device 121 to the switching device 116 using a third line (not shown). Also good. Of course, both the response request and the response may be transmitted using the wireless communication line 105.

  When the transmission unit 401 transmits a response request, the transmission unit 401 transmits transmission time information to the reception unit 402. When the reception unit 402 receives the response request, the reception unit 402 receives the response request and the transmitted transmission time information. From the time when the response request is transmitted, the time when the response request is received can be calculated and transmitted to the evaluation unit 403. Further, if the receiving unit 402 cannot receive a response request within a predetermined time, information indicating that a time-out has occurred can be transmitted to the evaluating unit 403.

  The length of the predetermined time can be equal to or shorter than the length of the transmission interval of the response request from the transmission unit 401. For example, when the transmission unit 401 transmits a response request every 2 seconds, the predetermined time can be set to 2.0 seconds or 1.9 seconds. In other words, the length of the transmission interval of the response request from the transmission unit 401 can be made longer than a predetermined time.

  The evaluation unit 403 evaluates the communication performance of the wireless communication line 105 based on the information transmitted from the reception unit 402. For example, if a response is not received in response to a response request or the time from the response request transmission to the response reception is not within a predetermined time, the communication performance of the wireless communication line 105 is constant. It is evaluated that it does not satisfy. Otherwise, it is evaluated that the communication performance of the wireless communication line 105 satisfies a certain condition. When the communication performance of the wireless communication line 105 does not satisfy a certain condition, the communication performance of the wireless communication line 105 is determined to be unsatisfactory (poor), and the communication performance of the wireless communication line 105 satisfies a certain condition. It can be assumed that the communication performance of the wireless communication line 105 is good. The evaluation result of the evaluation unit 403 is transmitted to the switching unit 404.

  The switching unit 404 uses the wireless communication line 105 or the communication line 106 as a line used by the terminals 111, 112, and 113 for communication with the server of the server system 102 according to the evaluation result transmitted from the evaluation unit 403. Make selections, make necessary settings, and switch lines. That is, when the evaluation unit 403 evaluates that the communication performance of the wireless communication line 106 is good, the wireless communication line 106 is selected and switched to use the wireless communication line 106. If it is evaluated that the communication performance of the wireless communication line 106 is not good, the communication line 106 is selected and the communication line 106 is switched to use. This switching is set by changing the routing information of the first router 115, for example. The evaluation transmitted from the evaluation unit 403 in the state where the routing information for the terminals 111, 112, 113 to communicate with the server of the server system 102 using the wireless communication line 105 is set in the first router 115 is the communication Assume that the performance is not good. At this time, the switching unit 404 sets the routing information of the first router 115 so that the communication line 106 is used as a line used for communication between the terminals 111, 112, 113 and the server of the server system 102. In addition, the evaluation transmitted from the evaluation unit 403 in a state where the routing information for the terminals 111, 112, 113 to communicate with the server of the server system 102 using the communication line 106 is set in the first router 115, Assume that the communication performance is good. At this time, the switching unit 404 changes and sets the routing information of the first router 115 so that the wireless communication line 105 is used as a line used for communication between the terminals 111, 112, 113 and the server of the server system 102. To do. As described above, the switching unit 404 is configured to use the wireless communication line 105 if the communication performance of the wireless communication line 105 is good, or to change the communication line if the communication performance of the wireless communication line 105 is not good. Control is performed so that 106 is used.

  Note that the evaluation unit 403 evaluates the communication performance depending on whether a response to the response request is received within a predetermined time each time a response request is transmitted from the transmission unit 401. And the communication line 106 are repeatedly switched in a short time, and communication between the terminal system 101 and the server system 102 may be unstable. Therefore, the evaluation unit 403 evaluates that the communication performance of the wireless communication line 105 is not good when a response to the response request from the transmission unit 401 is not received within a predetermined time for a predetermined number of times. . For example, if the response to the response request is not received within a predetermined time for seven consecutive times, it is evaluated that the communication performance of the wireless communication line 105 is not good. In this case, if the transmission unit 401 transmits a request for a response at intervals of 2 seconds, the wireless communication line 105 is connected to the communication line after 14 seconds or more have passed since the communication performance of the wireless communication line 105 actually deteriorated. It will be switched to 106. The amount of time that elapses after the communication performance of the wireless communication line 105 actually deteriorates is determined in consideration of the purpose of the communication system 100 and the like.

  In addition, after it is evaluated that the communication performance of the wireless communication line 105 is not good, the communication performance of the wireless communication line 105 is good when a response to the response request is received within a predetermined time even once. When the evaluation is performed, it may actually be undesirable because the communication line 106 is switched to the wireless communication line 105 in a state where the communication performance of the wireless communication line 105 is not stable. Therefore, after evaluating that the communication performance of the wireless communication line 105 is not good, the evaluation unit 403 continuously receives a response to the response request from the transmission unit 401 within a predetermined time. In this case, it may be evaluated that the communication performance of the wireless communication line 105 is good. For example, if the response to the response request is received within a predetermined time for 14 consecutive times, it is evaluated that the communication performance of the wireless communication line 105 is good. In this case, if the transmission unit 401 transmits a response request at intervals of 2 seconds, the wireless communication line 106 performs wireless communication after the communication performance of the wireless communication line 105 has actually improved for 28 seconds or longer. The line 105 is switched. The amount of time after which the communication performance of the wireless communication line 105 has actually improved is determined after the communication line 106 is switched to the wireless communication line 105 in consideration of the purpose of the communication system 100 and the like. Accordingly, after the communication performance of the wireless communication line 105 does not satisfy the predetermined condition and switches to the communication line 106, the wireless communication line 106 performs wireless communication when the communication performance of the wireless communication line 105 satisfies a condition different from the predetermined condition. It may be switched to the line 105.

  Note that the switching device 116 does not have to include all of the transmission unit 401, the reception unit 402, the evaluation unit 403, and the switching unit 404. That is, the switching device 116 can be configured by combining devices including any one or more of the transmission unit 401, the reception unit 402, the evaluation unit 403, and the switching unit 404. In this case, the switching device 116 is provided as a system in which a plurality of devices are combined. For example, as illustrated in FIG. 4B, the switching device (system) 116 includes a communication device 400-1 and an evaluation switching device 400-2. The communication device 400-1 includes a transmission unit 401 and a reception unit 402. Further, the evaluation switching device 4002- includes an evaluation unit 403 and a switching unit 404. Therefore, the switching device (system) 116 operates in the same manner as the switching device 116 and can be replaced with the switching device 116. In this case, the evaluation switching device 400-2 can be a switching system according to an embodiment of the present invention. When the evaluation switching device 400-2 is a switching system, the evaluation unit 403 of the evaluation switching device 400-2 (switching system) responds to a response request message transmitted to the response device via the wireless communication line. It can be defined that the communication performance of the wireless communication line is evaluated based on information related to reception of a response message returned from the apparatus.

  FIG. 5 is a flowchart of processing of the switching device 116. In step S501, the transmission unit 401 transmits a response request. Further, the transmission unit 401 can transmit information related to the transmission time of the response request to the reception unit 402. In step S502, the reception unit 402 determines whether a response has been received without timing out. That is, it is determined whether a response has been received within a certain period of time after the response request is transmitted. This determination is performed by the receiving unit 402, for example. If a response is received without timing out, the value of the variable t is set to 0 as the process of step S503, and the process is terminated. If a response cannot be received without timing out, the process proceeds to step S504, the value of the variable t is increased by 1, for example, and the process is terminated. When the process ends, for example, the process of step S501 may be started again after a predetermined length of time has elapsed.

  FIG. 6 is a flowchart of another process of the switching device 101. As the processing in step S601, the evaluation unit 403 sets the value of the variable t to 0. In step S602, it is determined whether the value of the variable t has exceeded a threshold value. For example, it is determined whether the value of the variable t exceeds 6 and becomes 7 or more. The fact that the value of the variable t exceeds the threshold means that the failure to receive a response without time-out occurs continuously for a number of times greater than the threshold value. Therefore, the process proceeds to step S603, where the switching table 404 rewrites the routing table of the first router 115 and changes the stored routing information. For example, “B5 via A2” is changed to “B5 via A3”.

  In step S604, the value of the variable t is set to 0, and in step S605, a pause is performed for a predetermined time. That is, the process of FIG. 6 is temporarily stopped before the transition to the process of step S606. For example, the process is stopped for 28 seconds. During this time, the process of FIG. 5 is executed once or more. Thereafter, the process proceeds to step S606, and it is determined whether or not the value of the variable t is 0. If the value of the variable t is 0, it means that the communication performance of the wireless communication line 105 has been improved. Therefore, the process proceeds to step S607 and the routing table of the first router 115 is restored. For example, “B5 via A3” is changed to “B5 via A2”. In step S606, if the value of the variable t is not 0, it is determined that the communication performance of the wireless communication line 105 is not good, and the process returns to step S604.

  As described above, in the present embodiment, the wireless communication line 105 and the communication line 106 are selected based on the evaluation of the communication performance of the wireless communication line 105. Accordingly, if the communication speed of the wireless communication line 105 is good and the line speed of the wireless communication line 105 is higher than that of the communication line 106, high-speed communication can be performed, and even if the communication performance of the wireless communication line 105 is not good, Communication via the communication line 106 can be secured. In addition, it is possible to eliminate the need to perform communication performance evaluation other than the switching device 116, for example, at the access point 103.

(Embodiment 2)
FIG. 7 shows a functional block diagram of a communication system according to Embodiment 2 of the present invention. Comparing the functional block diagram of the first embodiment with FIG. 7, in this embodiment, the first router A 2 is connected to the interface A 5 of the wireless LAN router 701, and the interface A 6 of the wireless LAN router 701 is connected to the wireless communication line 105. It is possible to communicate with the base station 104 via the network.

  In the present embodiment, the switching device 702 controls the wireless LAN router 701. In the first embodiment, for example, the switching device 116 changes the routing information of the first router. On the other hand, in this embodiment, the switching device 702 controls A5 of the wireless LAN router 701. More specifically, the operation of A5 of the wireless LAN router 701 is stopped (shut down) or restarted. In addition, in the present embodiment, the first router 115 can have a function of rewriting routing information depending on whether transmission / reception with the A5 of the wireless LAN router 701 is possible.

  FIG. 8 shows the routing information in the present embodiment, and shows the routing information when the communication performance of the wireless communication line 105 is good. The routing information of the terminals 111, 112 and 113 and the routing information of the second router are the same as in the first embodiment. In this embodiment, the routing information of “B5 via A2” is included. Further, the wireless router 701 has routing information of “B5 via A6” and “B1 via A6”. As a result, when the wireless LAN router 701 receives communication data addressed to the server system 102 from the first router 115, it is transmitted by A6. A response request from the switching device 702 is also transmitted by A6.

  In the present embodiment, the first router 115 communicates with the wireless router 701 to determine whether or not the A5 transmission / reception operation is stopped. For example, the first router 115 transmits an ICMP echo request to A5 of the wireless LAN router 701, and determines whether or not there is a response to the request, thereby confirming whether the transmission / reception operation of A5 has stopped. Judge whether. That is, if there is a response to ICMP echo request, it is determined that the transmission / reception operation of A5 is not stopped. In general, routers can exchange routing information using a protocol such as Routing Information Protocol. Therefore, depending on whether the first router 115 can exchange routing information with the wireless LAN router 701, It is determined whether the A5 transmission / reception operation is not stopped. If the first router 701 determines that the A5 transmission / reception operation is stopped, the routing information of “B5 via A2” is changed to “B5 via A3”. If a response to the ICMP echo request is obtained from the state in which the transmission / reception operation of A3 is stopped or the exchange of routing information becomes possible, it is determined that the transmission / reception operation of A5 is resumed. Then, the routing information of “B5 via A3” is changed to “B5 via A2”.

  FIG. 9 is a flowchart of processing of the switching device 702 according to the present embodiment. As a premise of this flowchart, it is assumed that the switching device 702 also executes the processing of the flowchart of FIG.

  As a process of step S901, the value of the variable t is set to zero. In step S902, it is determined whether the value of the variable t has exceeded a threshold value. If it is determined that the value of the variable t exceeds the threshold value, the process proceeds to step S903, and the switching unit 404 stops transmission / reception of A5. Next, as a process of step S904, the value of the variable t is set to 0, and as a process of step S905, a pause for a predetermined time is performed. After the pause, the process proceeds to step S906, and if the value of the variable t is 0, it is determined that the communication performance of the wireless communication line 105 has been improved. In the process of step S907, the switching unit 404 transmits and receives A5. To resume. If the value of the variable t is not 0 in step S906, it is determined that the communication performance of the wireless communication line 105 is not good, and the process returns to step S904.

  FIG. 10 is a flowchart of the processing of the first router 115 in this embodiment. In step S1001, it is determined whether communication with A5 of the wireless LAN router is possible. If it is determined that communication is not possible, the process proceeds to step S1002, the routing table is changed, and the routing information of “B5 via A2” is changed to “B5 via A3”. In step S1003, the process waits until communication with A5 of the wireless LAN router becomes possible. If it becomes possible, the process proceeds to step S1004 to restore the routing table.

  In the present embodiment, since the switching device 702 other than the first router 115 does not need to directly change the routing information of the first router 115, the routing information of the first router 115 needs to be stored in the switching device 702 or the like. There is no. Therefore, when there is a change in the network configuration in the terminal system 101, it is not necessary to change the routing information stored in the switching device 702 other than the first router 115. Thereby, in addition to the effects of the first embodiment, it is easier to change the setting of the routing information accompanying the change of the network configuration.

Claims (8)

A switching system that switches the communication line that the terminal uses for communication with the server.
An evaluation unit that evaluates the communication performance of the wireless communication line based on information related to reception of a response message transmitted from the response device to a response request message transmitted to the response device via the wireless communication line When,
A switching unit that switches the line used by the terminal for communication with the server to a communication line different from the wireless communication line if the communication performance of the wireless communication line does not satisfy the first condition by the evaluation by the evaluation unit; Having a switching system.   If the evaluation unit continuously detects that the response message cannot be received within a certain period of time after transmitting the response request message, the communication unit communicates with the wireless communication line. The switching system according to claim 1, wherein performance is evaluated as not satisfying the first condition.   The switching unit switches a line used for communication with the server of the terminal to the wireless communication line if the communication performance of the wireless communication line satisfies a second condition as a result of evaluation by the evaluation unit. 2. The switching system according to 2.   The evaluation unit evaluates that the communication performance of the wireless communication line does not satisfy the first condition, and then receives a response message within a certain time after transmitting a response message. 4. The switching system according to claim 3, wherein the communication performance of the wireless communication line is evaluated as satisfying the second condition if detected continuously exceeding the second threshold number of times.   If the communication performance of the wireless communication line does not satisfy the first condition as a result of the evaluation by the evaluation unit, the switching unit is connected to a wireless LAN router connected to the wireless communication line as a router serving as a default gateway of the terminal. The communication information of the router is stopped, and the routing information of the router is changed to the routing information in which the terminal communicates with the server using a communication line different from the wireless communication line. The switching system described.   The switching unit causes the wireless LAN router to start communication with the router if the communication performance of the wireless communication line satisfies the second condition as a result of evaluation by the evaluation unit, and the terminal receives routing information of the router. The switching system according to claim 5, wherein the switching information is changed to routing information for communicating with the server using the wireless communication line.   If the communication performance of the wireless communication line does not satisfy the first condition as a result of evaluation by the evaluation unit, the switching unit transmits routing information of a router serving as a default gateway of the terminal to the server and the wireless communication The switching system according to any one of claims 1 to 4, wherein the switching information is changed to routing information for communication using a communication line different from the line.   If the communication performance of the wireless communication line satisfies the second condition as a result of evaluation by the evaluation unit, the switching unit is configured such that the terminal communicates routing information of the router with the server using the wireless communication line. The switching system according to claim 7, wherein the switching system is changed to information.

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