JP2009164758A - Communication system, communication terminal, and network switching method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that there is no alternative means until a line failure is restored when online settlement processing becomes difficult due to the line failure, etc. <P>SOLUTION: In this communication system in which between a POS terminal 101 and a host system 122 is connected by at least two networks, a communication terminal is provided with a comparison means for comparing transmission data transmitted to a host system via a closed area IP network 108 with response data returned by the host system via one network; and a control means for switching a network to an ISDN exchange network 109 when the transmission data and the response data are not coincident or when the response data are not received. The communication terminal transmits the transmission data to the host system via the closed area IP network after switching to the ISDN exchange network, and the control means switches the network to the closed IP network when the comparison means detects coincidence between the transmission data and the response data. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a communication system, a communication terminal, and a network switching method, and more particularly, to a communication system and a communication terminal having a network switching function, and a network switching method used therefor.

  Until now, online payment processing has been carried out on public telephone lines or ISDN lines (Bch dial-up / Dch packets).

  In this case, the use of a Dch packet is the cheapest and one processing can be performed with several packets, so it costs 2-3 yen.

  For Bch dial-up connection on public lines or ISDN lines, a call charge of around 10 yen is required at a minimum depending on the billing by distance and call time.

  A flat-rate broadband connection using ADSL and optical fiber is becoming mainstream, and the use of a flat-rate IP network connection introduced for other purposes in online payment processing can further reduce the cost of online payment processing. Is coming out.

  In this way, there is a growing movement to implement online payment processing on networks that emphasize security such as IP-VPN connections using TCP / IP.

  However, at present, it can be said that the ADSL connection, whose communication quality depends on the distance from the carrier's station, and the IP network using the optical fiber connection currently deployed throughout Japan, are not as reliable as the ISDN line.

As a technique related to the present invention, in Patent Document 1, when the network controller determines that a failure has occurred in the first network, the network controller switches to the second network, and when the network controller recovers, the network controller switches to the first network. There is a description of that. Further, in Patent Document 2, a terminal transmits an IP packet, a router converts it into a D channel packet and transmits it to a host system, and a router converts an answer D channel packet from the host system into an IP packet. There is a description of forwarding.
JP-A-7-28726 (FIGS. 4 and 6) Japanese Patent Laying-Open No. 2005-020567 (FIG. 3)

  In online payment processing, broadband line, ISDN line, public telephone line, etc. are used as network infrastructure, but when online payment processing becomes difficult due to line failure, there was no alternative until line failure was recovered .

The communication system of the present invention is a communication system in which a communication terminal and a host system are connected by at least two networks.
The communication terminal is
Comparing means for comparing transmission data transmitted to the host system via one network and response data returned by the host system via the one network;
And control means for switching to another network when the transmission data and the response data do not match or when the response data is not received.

The network switching method of the present invention is a network switching method for a communication system in which a communication terminal and a host system are connected by at least two networks.
The communication terminal is
Comparing the transmission data sent to the host system via one network and the response data returned by the host system via the one network;
When the transmission data and the response data do not match, or when the response data is not received, the network is switched to another network.

The communication terminal of the present invention is a communication terminal connected to a host system in at least two networks,
Comparison means for comparing transmission data transmitted to the host system via one network and response data received from the host system via the one network;
And control means for switching to another network when the transmission data and the response data do not match or when the response data is not received.

  ADVANTAGE OF THE INVENTION According to this invention, the system which raised fault tolerance can be provided by enabling switching of a network infrastructure automatically or manually by the situation at the time of a failure.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram showing an example of an online payment system using a POS terminal.

  The broadband router 103 selects a router that accommodates an ISDN exchange network 109 and a closed IP network (IP-VPN) 108.

    The closed IP network 108 is contracted for a fixed amount IP-VPN in order to use TCP / IP packets. An optical fiber cable 107 is used for connection to a physical closed IP network. The ISDN exchange network 109 has an ISDN line packet contract in order to use the Dch packet.

  Normal online payment processing is performed using the closed IP network 108 and TCP / IP packets.

  In other words, in normal times, TCP packets transmitted from the POS terminal 101 are routed by the broadband router 103, and then broadband on the online payment center (host system) side via a communication carrier that develops the closed IP network 108. Routed to router 116. Further, the data is transferred to the online payment center host system 122 via the switching HUB 120 or the like. In this case, the fee for online payment processing does not depend on the number of online payment processing (number of packets) due to a flat-rate IP-VPN contract.

  When a failure or the like occurs in the closed IP network 108, the infrastructure is switched to the ISDN exchange network 109, and the online payment process can be continued using the Dch packet instead of the TCP / IP packet.

    That is, at the time of injury, the TCP packet transmitted from the POS terminal 101 is converted into a Dch packet by the broadband router 103 and transferred to the ISDN line accommodating terminal 117 via a communication carrier that develops the ISDN exchange network 109. The ISDN line accommodating terminal 117 converts the Dch packet into a TCP packet and transfers it to the online payment center host system 122. In this case, the fee for online payment processing is a pay-per-use charge based on the number of Dch packets (0.4 yen or 0.8 yen per packet).

  FIG. 15 is a diagram showing sales processing software as an example of the components related to the network switching processing of the POS terminal 101.

  The POS terminal 101 is a terminal having a screen and a user interface such as key input and touch panel input. The sales processing software 1002 is activated from the user interface 1001.

  The sales processing 1002 includes a credit processing software module 1003 linked with the ISDN communication library 1004 as a processing module. The credit processing software module 1003 links the ISDN communication library 1004 in order to use the line control software 1005 for the purpose of data communication with the online payment center 122. The line control software 1005 links the TCP / IP socket library 1006 and is connected to the Ethernet (registered trademark) LAN via the TCP / IP protocol stack 1007, the LAN adapter driver 1008, and the LAN adapter 1009, and is physically a broadband router. 103 and TCP / IP communication on an Ethernet LAN.

  FIG. 16 shows a flow related to credit processing as an example of the processing routine of the sales processing software 1002. A description of screen display, sales input, and sales data creation is omitted. The process of reading credit card data with a card reader or the like is expressed as [card input] 1101, but [sales request message creation] 1102 is executed based on the credit card data input here, and [sales request] Telegram] 1103 is stored in the memory.

  The ISDN communication library isdn_call function is used to make a call 1104 to the host, the isdn_sense function is used to check the line connection, the isdn_status function is used to check the data communication status, and the isdn_send function Then, the previous [sales request message] 1103 is specified and [sales request message transmission] 1105 is executed. Then, the sales response message is received using the isdn_receive function. If the credit settlement is OK, the sales are completed normally. If credit card payment is NG, it ends with a sales error (payment refusal).

  FIG. 17 is a diagram showing an outline of the processing flow of the isdn_call function.

  By executing [Connect to PORT = 30020 of router] 1201, the dial-up router 113 automatically makes a call.

  [Connection OK?] 1202 determines, and if the connection process is normal, the result of [return OK] 1203 is returned to the caller.

  If the connection process is abnormal, the result of [return NG] 1204 is returned to the caller.

  FIG. 18 is a diagram showing an improved isdn_call function obtained by adding an automatic detection function of line selection to the isdn_call function of FIG.

  [Normal or failure] 1205 detects an internal state indicating the current line selection destination.

  If it is normal, it will connect to the broadband line, [Connect to router PORT = 30030] 1201 is executed, and if [Connection OK?] 1202 is OK, [return OK] 1203 is returned to the caller To do. [Connection OK?] If the determination of 1202 is NG, it is determined that the broadband line cannot be used, [Connect to router PORT = 30020] 1206 is executed, and [Connection OK?] 1207 determination is OK. For example, the internal state is changed to the time of failure, and [return OK] 1203 is returned to the caller. If the determination of [Connection OK?] 1207 is NG, [return NG] 1204 is returned to the caller, and the internal state is not returned as normal.

  FIG. 19 is a diagram showing an outline of the processing flow of the isdn_send function.

  [Transmission data to router] 1301 transmits the transmission data received from the caller, and the processing result is determined by [transmission OK?] 1302. If OK, [return OK] 1303 is returned to the caller. [Send OK?] Is determined in 1302, and if it is NG, [return NG] 1304 is returned.

  FIG. 20 is an improvement of the isdn_send function shown in FIG. 19 by adding the re-call processing by the isdn_call function shown in FIG. 18 and automatically changing the data transmission destination in the event of a failure from the normal time. If the transmission data requested by the caller is transmitted by [data transmission to router] 1301, and the determination is OK by [transmission OK?] 1302, the flow for returning [return OK] 1303 to the caller is the same. When the judgment result is NG, the judgment is further carried out with [Failure or Normal] 1305. When the trouble occurs, the internal state has already shifted to the trouble, so an error occurred on the ISDN line. Assume that [return NG] 1304 is returned to the caller.

  [Failure or normal] When the determination of 1305 is normal, the isdn_call function is executed internally. According to FIG. 18, [connection of router to PORT = 30020] 1206 is automatically executed. , OK or NG will be returned. The return value of this isdn_call is determined by [OK?] 1307, and if it is OK, the transmission data requested by the caller of the isdn_send function is transmitted by [Data transmission to router] 1308. [Send OK?] 1309 makes a further determination, and if OK, similarly to [Send OK?] 1302, [return OK] 1303 is returned to the caller. When [Send OK?] 1309 is NG, the isdn_call function re-call process in the isdn_send function in FIG. 20 is effective as a retry process in the conventional isdn_send function. Often implemented and rarely implemented in isdn_send.

  In this way, it is possible to introduce an automatic line selection method without changing the credit processing software module 1003 in FIG.

Below is a list of ISDN communication library functions (outline).
FRAPI-A library
isdn_open Starts ISDN line control
isdn_close End ISDN line control
isdn_call Place a call on an ISDN line
isdn_accept Allows incoming call to ISDN line
isdn_response: Incoming call to ISDN line
isdn_release Releases an ISDN line
isdn_send Sends data via ISDN line
isdn_receive Receive data via ISDN line
isdn_status Get ISDN line 3 status
isdn_sense Get ISDN line status (Description of operation)
Online payment processing includes card balance confirmation processing, card sales processing, card deposit processing, and cancellation processing. Here, data exchange using two network infrastructures will be described taking a card balance confirmation process at the normal time and a card sales process at the time of failure as examples.

  FIG. 2 shows a sequence related to the card balance confirmation processing 201 exchanged between the POS terminal 101 and the online payment center 122.

In the normal card balance confirmation process 201,
First, in order to establish a session (connection), the POS terminal 101 transmits TCP-SYN (packet for session establishment) to the TCP port number 30030 of the broadband router 103. The broadband router 103 transfers TCP-SYN to the counterpart broadband router 116 as it is, and the data is transferred to the online payment center 122. The TCP port number on which the online payment center 122 is waiting in this case is also 30030. If the online payment center 122 can be connected, it returns a TCP-ACK-SYN (packet for session establishment confirmation response) via the broadband routers 116 and 103. The POS terminal 101 that has received TCP-ACK-SYN transmits TCP-ACK (packet for confirmation response) to the online payment center 122 via the broadband routers 103 and 116.

  When the session is established, the POS terminal 101 transmits a balance request message as data to the TCP port number 30030 of the broadband router 103. The broadband router 103 transfers the TCP packet to the partner broadband router 116 as it is, and the data is transferred to the online settlement center 122. The TCP port number on which the online payment center 122 is waiting in this case is also 30030.

  The online settlement center 122 performs balance confirmation and negative check on the requested card based on the negative card data, card balance data, etc., and returns the card balance in a balance response message. The balance response message is transferred via the broadband router 116 and the broadband router 103, and the POS terminal 101 receives this message.

  When the session is disconnected, TCP-FIN (packet for session termination) is transmitted to the online payment center 122 as a connection destination via the broadband routers 103 and 116. The online payment center 122 recognizes the end and returns a TCP-ACK-FIN (packet for session end confirmation response) via the broadband routers 116 and 103. Then, the POS terminal 101 that has received TCP-ACK-FIN transmits TCP-ACK (packet for confirmation response) to the online payment center 122 via the broadband routers 103 and 116.

  FIG. 3 shows a sequence related to the card sales process 301 exchanged between the POS terminal 101 and the online payment center 122.

  In the card sales process 202 at the time of failure, TCP-SYN (packet for session establishment) is transmitted to the TCP port number 30020 of the broadband router 103 in order to establish a session. The broadband router 103 sets the telephone number of the ISDN line accommodating terminal 119 and transmits a call request (CR packet) to the ISDN exchange network 109 in order to transfer the data received at this dedicated TCP port as a Dch packet. The ISDN exchange network 109 transmits an incoming call instruction (CN packet) to the ISDN line accommodating terminal 119, and the ISDN line accommodating terminal 119 transmits TCP-SYN to the online settlement center 122. If the online payment center 122 can connect, the TCP-ACK-SYN (packet for session establishment confirmation response) is transmitted to the ISDN line accommodating terminal 119, and the ISDN line accommodating terminal 119 performs an incoming call confirmation (CA packet). Transmit to the ISDN exchange network 109. The ISDN exchange network 109 transmits a connection completion (CC packet) to the broadband lator 103. The broadband router 103 that has received the connection completion (CC packet) transmits TCP-ACK-SYN to the POS terminal 101. The POS terminal 101 that has received TCP-ACK-SYN transmits TCP-ACK (packet for confirmation response) to the broadband router 103 and establishes a VC connection of the ISDN line Dch.

  When the VC connection is established, the POS terminal 101 transmits a sales request message (TCP packet) as data to the TCP port number 30020 of the broadband router 103. The broadband router 103 transfers the sales request message (DT packet) to the ISDN line accommodating terminal 119 via the ISDN exchange network 109. The ISDN line accommodating terminal 119 converts the received DT packet into a TCP packet, and transmits it to the TCP port number 30030 on which the online payment center 122 is awaiting, as in normal times. When the online payment center 122 receives the sales request message, it compares the card data and the sales amount based on the negative card data, card balance data, etc., creates the sales data, and sends the sales response message (TCP packet) to the ISDN line. It returns to the accommodation terminal 119.

    The ISDN line accommodating terminal 119 converts the received TCP packet into a DT packet and transfers it as a sales response message (DT packet) to the broadband router 103 via the ISDN exchange network 109. The broadband router 103 converts the received DT packet into a TCP packet and transmits it to the POS terminal 101 as a sales response message (TCP packet).

  When the VC is disconnected, TCP-FIN (packet for VC connection termination) is transmitted to the broadband router 103. The broadband router 103 transmits a restoration request (CQ packet) to the ISDN exchange network 109. Then, the ISDN exchange network 109 transmits a disconnection instruction (CI packet) to the ISDN line accommodating terminal 119, and the ISDN line accommodating terminal 119 transmits TCP-FIN to the online settlement center 122. The online payment center 122 recognizes the end and returns a TCP-ACK-FIN (VC connection end confirmation response packet) to the ISDN line accommodating terminal 119. The ISDN line accommodating terminal 119 transmits a restoration confirmation (CF packet) to the broadband router 103 via the ISDN exchange network 109. The broadband router 103 that has received the restoration confirmation (CF packet) transmits TCP-ACK-FIN to the POS terminal 101. The POS terminal 101 that has received TCP-ACK-FIN transmits TCP-ACK (packet for confirmation response) to the broadband router 103.

  As described in the above method, when the broadband router 103 receives data at the TCP port number 30030, the broadband router 103 transfers the TCP packet to the online payment center 122 via the closed IP network 108.

  In the alternative processing, when the broadband router 103 receives data at the TCP port number 30020, the broadband packet 103 is converted into a Dch packet and transferred to the online payment center 122 via the ISDN exchange network 109.

  In this way, a mechanism for distinguishing between a normal time and a failure time is realized by the TCP port number.

  FIG. 4 shows the function of the injury detection process 401 for automatically detecting a failure.

  The POS terminal 101 uses the Internet control notification protocol to detect a failure by sending and receiving ICMP messages.

  Here, the IP address of the POS terminal 101 is 192.168.0.101, the IP address of the online payment center 122 is 192.168.1.101, and the failure detection process 401 transmits an echo request notification (ICMP message) to the online payment center 122. The broadband routers 103 and 116 transfer this ICMP message. The online payment center 122 that has received the echo request notification returns an echo response notification (ICMP message) in which the received data is set to the POS terminal 101 via the broadband routers 116 and 103. When this ICMP message is transferred normally, the POS terminal 101 compares the received data in this message with the transmission data set in the echo request notification, and determines that it is normal if they match. When it is determined to be normal, the next failure detection process 402 is performed after the interval timer 403 has passed 30 seconds.

  If the received data does not match the transmitted data, a failure is detected and an alternative process is performed.

  In the failure detection processing 402, if any failure occurs between the POS terminal 101 and the online payment center 122, the POS terminal 101 cannot receive an echo response notification for the transmitted echo request notification, and therefore times out (10 seconds in FIG. 4). Will time out later). When this timeout occurs, a failure is detected, and an alternative process is performed.

  The failure detection process is periodically performed at a time defined by the interval timer 403 and regularly monitors the online payment center 122.

  FIG. 5 shows the function of the recovery detection process 501 for automatically detecting failure recovery.

  In the event of a failure, the POS terminal 101 performs the recovery detection process 501 at intervals of the interval timer 503 as in FIG. 4, and periodically transmits an echo request notification. Since the response waiting timer always times out in the event of a failure, the failure will continue continuously. That is, in the failure detection process 501, if any failure occurs between the POS terminal 101 and the online payment center 122, the POS terminal 101 cannot receive an echo response notification for the transmitted echo request notification, and therefore times out (in FIG. 5). Timeout after 10 seconds). When a timeout occurs, the interval timer 403 performs the next failure detection process 502 after 30 seconds have elapsed.

  When the failure between the POS terminal 101 and the online payment center 122 is recovered, an echo response notification for the echo request notification transmitted by the recovery detection processing 502 is received, and after a data comparison is made, recovery is detected and recovery is performed. Processing is performed. If the data does not match after the data comparison, a failure is detected.

  4 and 5, the POS terminal 101 recognizes the failure and normality in the same procedure except for the distinction between the normal state and the failure state.

  As described above, the POS terminal 101 can always monitor the abnormality of the communication state with the online payment center 122 and display the state on the POS terminal screen.

  FIG. 6 shows a screen of the POS terminal 101 at the normal time, and FIG. 7 shows a screen of the POS terminal 101 at the time of failure.

  FIG. 6 is an example of a sales screen in the POS terminal 101, and “BB-OK” indicating that the broadband line is normal is displayed in the 601 portion (normal time).

  FIG. 7 displays “ISDN” indicating that the ISDN line is selected in the portion 701 by the substitute processing due to the failure of the broadband line (at the time of failure).

  In general, failure confirmation by echo request notification-echo response notification using an ICMP message is an effective method, but a large number of ICMP messages may be prohibited on the Internet or the like.

  In this case, since failure detection cannot be performed, there is a case where an alternative process is manually selected when the online payment process ends in error due to a timeout or the like.

  Therefore, the POS terminal 101 includes a user interface for manually selecting an alternative process when a normal online payment process results in a communication error.

  An example of the screen of the POS terminal 101 showing this situation is shown in FIG.

  When the “Yes (recommended)” button 801 is pressed, an alternative process is executed. When the “No” button 802 is pressed, the substitution process is not executed. In this way, the user can freely select a network according to the situation.

According to the configuration of the present embodiment, the following effects can be obtained.
(1) By accommodating multiple network infrastructures for online payment processing, online payment processing can be used continuously even in the event of a failure.
(2) The online payment process can be continuously operated by automatically detecting a failure.
(3) A normal online payment process can be performed by automatically detecting recovery.
(4) The network can be switched manually as appropriate, and it is possible to deal with failures that cannot be automatically detected.
(5) The selected network classification can be displayed on the POS screen.

(Second Embodiment)
The broadband router 103 shown in FIG. 1 may be divided into a broadband router 103 and a dial-up router 912 as shown in FIG. The S / W-HUB 911 is used as an Ethernet HUB.

  FIG. 12 shows an example of connection of a plurality of terminals by the gateway system A01 in a POS system at a gas station.

  As in FIG. 9, the POS terminal 101 is connected to the S / W-HUB A03 via an Ethernet cable and connected to the broadband router 103.

  All of the order machines A02 (here, external POSTs # 1 to #n) corresponding to POS used outdoors are connected to the broadband router 103 by S / W-HUB A03. Similarly, the gateway system A01 that relays online payment is connected to the broadband router 103 via the S / W-HUB A03.

  All communication data for online payment processing is converted or routed by the gateway system A01 and transmitted / received via the broadband router 103.

  FIG. 13 shows a card balance confirmation process A21 as an example of a data sequence related to an online payment process using a normal gateway system.

  Except that the TCP port number is 30020, the data sequence between the POS terminal 101 and the gateway system A01 is the same procedure as the data sequence between the POS terminal 101 and the broadband router 103 shown in FIG. For example, to establish a session (connection), the POS terminal 101 transmits TCP-SYN (packet for session establishment) to the TCP port number 30020 of the gateway system A01. The gateway system A01 that has received TCP-SYN transmits TCP-SYN to the TCP port number 30030 of the broadband router 103.

  FIG. 14 shows an example of card sales processing A31 as a data sequence related to online payment processing using the gateway system at the time of failure.

  The data sequence between the external POST A02 (external POST # 1 to #n) and the gateway system A01 is the same procedure as the data sequence between the POS terminal 101 to the broadband router 103 shown in FIG.

  Since the POS terminal 101 and the external POST A02 can realize online payment processing in the same procedure with respect to the gateway system A01, it is not necessary to recognize whether the online processing is a normal time or a failure time automatically. Conversion and transfer are performed by the gateway system A01.

(Third embodiment)
The connection to the closed IP network 108 in FIG. 1 may be changed from an optical fiber connection to an ADSL connection using an ADSL modem 921 as shown in FIG.

(Fourth embodiment)
The closed IP network (IP-VPN connection) 108 shown in FIG. 1 may be connected to the Internet via the provider area IP network. In this case, the configuration shown in FIG.

  The configuration of each embodiment described above has a function that enables online payment processing using two networks in online payment processing in card payment using a credit card, David card, etc. By enabling automatic or manual switching of network infrastructure, a system with improved fault tolerance can be configured.

  In addition, the currently selected network can be displayed on the POS terminal screen.

  Although a dedicated terminal may be used as the POS terminal, the POS function can be realized by software using a computer.

  The present invention can be used for an online payment processing of a POS terminal or an online payment dedicated terminal installed in a small to medium-sized store.

It is a figure which shows an example of the online payment system using the POS terminal concerning the 1st Embodiment of this invention. It is a figure which shows the sequence in connection with the card balance confirmation process exchanged with a POS terminal and an online payment center. It is a figure which shows the sequence in connection with the card sales process exchanged by a POS terminal and an online payment center. It is a figure which shows the function of the injury detection process which detects a fault automatically. It is a figure which shows the function of the recovery detection process which detects a fault recovery automatically. It is a figure which shows the screen of the POS terminal 101 at the normal time. It is a figure which shows the screen of the POS terminal 101 at the time of a failure. It is a figure which shows the screen of the POS terminal 101 which shows the user interface which selects an alternative process manually when the online payment process at the time of normal becomes a communication error. It is a figure which shows the structure of the 2nd Embodiment of this invention which divided | segmented the broadband router 103 shown in FIG. 1 into the broadband router 103 and the dialup router 912. FIG. It is a figure which shows the structure of the 3rd Embodiment of this invention which changed the connection to the closed IP network of FIG. 1 from the optical fiber connection to the ADSL connection using the ADSL modem 921. It is a figure which shows the structure of the 4th Embodiment of this invention which made the closed area IP network (IP-VPN connection) 108 of FIG. 1 the internet connection via a provider area | region IP network. It is a figure which shows the POS system of a gas station in the example of the multiple terminal connection by gateway system A01. It is a figure which shows the card balance confirmation process A21 as a data sequence relevant to the online payment process using the gateway system at the normal time. It is a figure which shows the card sales process A31 as a data sequence relevant to the online payment process using the gateway system at the time of a failure. It is a figure which shows a sales process software as an example about the component regarding the network switching process of the POS terminal 101. FIG. It is a figure which shows the flow regarding a credit process as an example of the processing routine of the sales processing software. It is a figure which shows the outline | summary of the processing flow of an isdn_call function. It is a figure which shows the isdn_call function which added the automatic detection function of the line selection to the isdn_call function of FIG. It is a figure which shows the outline | summary of the processing flow of an isdn_send function. FIG. 20 is a diagram showing an improved version of the isdn_send function shown in FIG. 19 with the addition of a re-call process using the isdn_call function shown in FIG. 18 and the process of automatically changing the data transmission destination when a failure occurs from the normal time.

Explanation of symbols

101 POS (Point Of Sales) terminal 102 Ethernet cable 103 Broadband router (with dial-up router function)
104 Telephone cable 105 Ethernet cable 106 ONU (Optical Network Unit)
107 Optical cable 108 Closed IP network (IP-VPN network)
109 ISDN switching network (X.25 Dch packet network)
110 Optical cable 111 Telephone cable 112 ONU (Optical Network Unit)
113 DSU (Digital Service Unit)
114 Optical cable 115 ISDN cable 116 Broadband router 117 ISDN line accommodating terminal 118 Ethernet cable 119 Ethernet cable 120 S / W-HUB (switching HUB)
121 Ethernet cable 122 Online payment center host system

Claims (6)

In a communication system in which a communication terminal and a host system are connected by at least two networks,
The communication terminal is
Comparing means for comparing transmission data transmitted to the host system via one network and response data returned by the host system via the one network;
And a control means for switching to another network when the transmission data does not match the response data or when the response data is not received. The communication system according to claim 1,
The communication terminal, after switching to the other network, sends transmission data to the host system via the one network,
The control means switches to the one network when the comparison means detects a match between the transmission data and the response data. In a network switching method of a communication system in which a communication terminal and a host system are connected by at least two networks,
The communication terminal is
Comparing the transmission data sent to the host system via one network and the response data returned by the host system via the one network;
A network switching method characterized by switching to another network when the transmission data and the response data do not match or when the response data is not received. In the network switching method according to claim 3,
The communication terminal, after switching to the other network, sends transmission data to the host system via the one network,
A communication system characterized by switching to the one network when a match between the transmission data and the response data is detected. A communication terminal connected to a host system in at least two networks,
Comparison means for comparing transmission data transmitted to the host system via one network and response data received from the host system via the one network;
And a control means for switching to another network when the transmission data and the response data do not match or when the response data is not received. The communication terminal according to claim 5,
The control means sends the transmission data addressed to the host system via the one network after switching to the other network, and when the comparison means detects a match between the transmission data and the response data, A communication terminal characterized by switching to a single network.

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