JP2006020202A - Communication equipment, method, and program for controlling communication - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily perform check of a communication line for switching control of the communication line in a device which selectively uses multiplexed communication lines to perform communication with each other. <P>SOLUTION: In the case of deciding normal/abnormal of each communication line, health check packets are transmitted from both pieces of communication equipment to each communication line, respectively and when no response to it is obtained in the communication line under selection, the communication line is switched. Consequently, even when a failure occurs in any of an outward communication line and/or a return communication line, in the case of commonly recognizing the failure by both of the communication equipment for synchronization of switching timing, etc., it is not necessary to confirm contents of data expressing abnormality like in the case of checking the communication line by one-way communication from the health check packet transmitted from the partner's side and both pieces of the communication equipment commonly recognize the state of the communication line by whether or not a reply to the health check packet from self-equipment is returned. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a communication device, a communication control method, and a communication control program used for an IP (Internet Protocol) network and the like, and in particular, selectively switches a multiplexed communication line such as a duplex when a failure occurs. It relates to what to use.

  Traditionally, entities that operate social infrastructure such as banks, railroads, electricity, gas, water, etc., have restricted access from outside of specific devices such as ATMs and host computers. It is carried out with a duplexed business-use dedicated line. Then, as described above, it is selectively used when a failure occurs. However, such a dedicated line is inefficient because the line is always secured one-to-one or one-to-many regardless of whether or not communication is performed. Therefore, it is conceivable to construct the communication line with an IP network and operate it efficiently.

  Generally, in the IP network, when a failure occurs, the router or switching hub adjacent to the failure location detects the failure, automatically searches for a detour route, switches the communication path, and continues communication. It can be done. However, the switching usually takes about 1 minute, and the router or switching hub cannot store data during the period, and there is a problem that the data during this communication disabled period is discarded. In addition, if it takes time to resume communication in this way, there will be a great limitation on applicable applications.

  Therefore, in order to solve such a problem, when the IP network is duplicated and a failure occurs in the communication line in use, the communicating devices communicate with each other to immediately switch to the other communication line. It is conceivable to switch the line. Patent Document 1 describes a typical prior art that monitors such a duplicated IP network, detects that a failure has occurred, and switches automatically.

  FIG. 4 is a diagram showing a health check sequence according to the conventional technique. In this prior art, a health check packet is transmitted from each of two terminals at a predetermined time W, and on the receiving side, the health check packet transmitted at each time W is transmitted a predetermined number of times (in FIG. If the health check packets 13, 14, and 15 (downward from terminal 3 to terminal 2) are not received, it is determined that a line failure has occurred.

Therefore, in order for both terminals to share information that a line failure has occurred, some signal must be transmitted after determining the line failure. In FIG. 4, an uplink health check packet from the terminal 2 to the terminal 1 is used as the signal. As a result, the two terminals can perform line switching in synchronism, and can be applied to applications in which problems occur if switching is performed individually at an arbitrary timing.
JP 2003-18217 A

  However, in the above-described conventional technology, each terminal checks the communication line by one-way communication from the health check packet transmitted from the other party, so that information indicating that a line failure has occurred as described above. In order to be shared by both terminals, a signal indicating that must be transmitted from the terminal on which the occurrence of the line failure is detected (terminal 2 in FIG. 4) to the other terminal. In order to determine whether a health check packet has been received or a signal indicating such an abnormality has been received, it is necessary to analyze the received data. Therefore, in order to monitor abnormalities that occur rarely, it is necessary to analyze the health check packet every time, and there is a problem that the communication line check is complicated. In addition, once an abnormality is determined, health check packets are no longer transmitted and the communication line is no longer checked. Therefore, the communication line is classified into a primary system and a secondary system based on data transmission capacity. However, when the primary system is used with priority, a fault occurs in the primary system, and even if the primary system is switched to once, once the fault in the primary system is resolved, it can be quickly restored to the primary system. There is also a problem that it becomes impossible.

  An object of the present invention is to provide a communication device, a communication control method, and a communication control program that can easily check a communication line.

  The communication device of the present invention, in a device that communicates with each other using multiplexed communication lines, transmits a health check packet to each communication line from the communication interface of both communication apparatuses, and a reply to that is selected. A communication control unit is provided for switching the communication line when it cannot be obtained with the communication line inside.

  According to the above configuration, one of the duplicated communication lines is used, and the multiplexed communication lines are selectively used for mutual connection as in the case of switching to the other due to the occurrence of a failure or the like. In the communication apparatus, in order to determine the normality / abnormality of each communication line for the switching control of the communication line, in the present invention, a communication control unit is provided, and communication is performed via the communication line. A health check packet is transmitted from each communication interface to each communication line. Then, when a reply to the selected communication line cannot be obtained by the communication interface, the communication control unit switches the communication line.

  Therefore, both communication apparatuses can check each communication line arbitrarily by reciprocating communication, so that it is possible to easily confirm whether the response is a response to the health check packet from the own device by the packet number or the like. As a result, even if a failure occurs in either the outgoing communication line and / or the return communication line, both communication devices can recognize this for synchronization of the switching timing. There is no need to check the contents of the data indicating the abnormality, as in the case of checking the communication line by one-way communication from the health check packet sent from the other side, and the reply to the health check packet from the own machine Depending on whether or not the communication line has returned, both communication apparatuses can recognize the state of the communication line and can easily check the communication line.

  In addition, if there is a response to the health check packet from the own device, it can be determined that the failure or the like in the communication line has been solved and the communication line can be used again. If the main system is used with priority, the main system will fail, and even if it is switched to the subordinate system once the main system fault is resolved, the main system Is particularly preferable.

  In the communication apparatus of the present invention, the communication control unit switches the communication line when a reply to the transmitted health check packet cannot be obtained a predetermined number of times.

  According to the above configuration, the communication control unit does not react excessively to an instantaneous failure such as noise intrusion into the communication line, and can suppress undesired switching.

  Furthermore, in the communication apparatus of the present invention, when the communication control unit switches the communication line, the switched communication line receives a response to the transmitted health check packet for a predetermined number of times. It is characterized by switching to.

  According to the above configuration, even when the communication line is restored from a failure, such as when the main line is once switched to the slave system, the communication control unit is configured so that the switched communication line is Since the switching is delayed until the transmission / reception of the health check packet is confirmed for the predetermined number of times, the switching can be performed after the communication line is stabilized.

  In the communication apparatus of the present invention, the communication line is a dedicated line having access restriction from outside.

  According to the above configuration, in entities that operate social infrastructure such as banks, railroads, electricity, gas, water, etc., communication between specific devices such as ATMs and host computers so far has not been possible from outside. Although it has been performed on a multiplexed business-use dedicated line with access restrictions, the dedicated line is constructed on the IP network, and the communication device is used to adjust the period of the health check packet, thereby adjusting the dedicated line. In addition, the versatility of the dedicated line can be expanded while ensuring the switching response required for the communication, and it can also be used for other communications such as in-house telephones and data communications.

  Furthermore, the communication control method of the present invention is a method of performing communication with each other selectively using multiplexed communication lines, in which both communication devices transmit health check packets to the respective communication lines, It is characterized in that the communication line is switched when the reply to it cannot be obtained on the selected communication line.

  According to the above configuration, one of the duplicated communication lines is used, and the multiplexed communication lines are selectively used for mutual connection as in the case of switching to the other due to the occurrence of a failure or the like. In the method of performing communication, in order to determine the normal / abnormality of each communication line for the control of switching the communication line, in the present invention, both communication devices that perform communication via the communication line Each health check packet is sent to the line. Then, the communication line is switched when a response to the selected communication line cannot be obtained.

  Therefore, both communication apparatuses can check each communication line arbitrarily by reciprocating communication, so that it is possible to easily confirm whether the response is a response to the health check packet from the own device by the packet number or the like. As a result, even if a failure occurs in either the outgoing communication line and / or the return communication line, both communication devices can recognize this for synchronization of the switching timing. There is no need to check the contents of the data indicating the abnormality, as in the case of checking the communication line by one-way communication from the health check packet sent from the other side, and the reply to the health check packet from the own machine Depending on whether or not the communication line has returned, both communication apparatuses can recognize the state of the communication line and can easily check the communication line.

  In addition, if there is a response to the health check packet from the own device, it can be determined that the failure or the like in the communication line has been solved and the communication line can be used again. If the main system is used with priority, the main system will fail, and even if it is switched to the subordinate system once the main system fault is resolved, the main system Is particularly preferable.

  A communication control program according to the present invention causes a communication interface of a computer to execute the above communication processing procedure.

  According to the above configuration, when performing communication with each other selectively using multiplexed communication lines, it is possible to easily perform a check for switching control of communication lines and to eliminate troubles. Therefore, it is possible to realize a communication control program that can also determine that it can be used again.

  As described above, the communication device, communication control method, and communication control program of the present invention uses one of the duplex communication lines, and switches to the other when used due to a failure or the like. In an apparatus that selectively communicates with each other using a communication line that has been changed, the communication line is controlled to determine whether each communication line is normal or abnormal for the purpose of switching control of the communication line. A health check packet is transmitted to each communication line from both of the communication apparatuses to be performed, and the communication line is switched when a reply to the selected communication line cannot be obtained.

  Therefore, both communication devices can check each communication line arbitrarily by round-trip communication, so that it is possible to easily check whether the response is a response to the health check packet from the own device by the packet number or the like. The communication line can be easily checked.

  FIG. 1 is a block diagram showing a configuration of a communication system including communication apparatuses 1 and 2 according to an embodiment of the present invention. The communication system according to the present invention includes a number of routers R11, R12, R13, R14; R21, R22, R23, R24;... (When collectively referred to as reference symbol R below) and switching hubs H11, H12; H21, H22;... (Generally referred to as “H” hereinafter) are realized by setting a duplex communication line as indicated by the reference symbols L1 and L2 in the IP network 3 constructed. Is done. The communication lines L1 and L2 may be equal to each other, but here the communication line L1 has a larger transmission capacity than the communication line L2, the communication line L1 is the main communication line, and the communication line L2 Is a secondary communication line.

  The communication devices 1 and 2 are connected to terminal devices 5 and 6 realized by personal computers or workstations, respectively. These terminal devices 5 and 6 are connected to the communication devices 1 and 2 via the IP network 3. Communicate with each other. Since the communication devices 1 and 2 perform communication using the duplexed communication lines L1 and L2, transmission packets from the terminal devices 5 and 6 are copied by the communication devices 1 and 2, and both communication Data equal to each other is transmitted to the lines L1 and L2. As for the received data, only the data on the selected communication line side is output to the terminal devices 5 and 6, and the data transmitted on the non-selected side communication line is discarded.

  In the communication system configured as described above, the communication lines L1 and L2 are set in the communication apparatuses 1 and 2, and the communication apparatuses 1 and 2 preferentially use the main communication line L1. It becomes like this. When a line failure occurs as indicated by reference symbol P in any of the routes H11-R21-R22-R23-R24-H12 constituting the main communication line L1 (between R22 and R23 in FIG. 1). The routers R22 and R23 adjacent to the failure point P automatically search for a bypass route, and when the bypass route is established as indicated by reference characters L1 ′ and L1 ″, thereafter, the bypass route L1. Switch to “or L1” to continue communication. Which of the detour routes L1 'and L1 "is selected depends on the settings of the routers R22 and R23.

  However, the switching of the communication path by the routers R22 and R23 normally takes about 1 minute as described above, and the fact that a line failure has occurred is transferred from these routers R22 and R23 to the communication devices 1 and 2. Not notified. Furthermore, the router R and the switching hub H cannot accumulate data during that time, and the data during this communication incapability is discarded. Therefore, in the present invention, as described in detail below, the communication apparatuses 1 and 2 each transmit a health check packet and monitor the line state. When the line failure occurs in the main communication line L1, the communication path is once switched to the slave communication line L2, and when the line trouble is resolved, the communication path is returned to the main communication line L1.

  FIG. 2 is a diagram showing a health check sequence according to the present invention. In the present invention, a health check packet is transmitted from each of the two communication devices 1 and 2 serving as communication terminals at a predetermined time W, for example, every second, and the receiving side responds with, for example, the same packet number or the like. A reply packet corresponding to the transmitted packet is returned. Then, if the returned packet corresponds to the transmitted packet, the transmitting side determines that the line is normal. On the other hand, when there is no reply or when the returned packet does not correspond to the transmitted packet, it is determined that the line is abnormal, and the communication lines L1 and L2 are switched.

  In FIG. 2, a line abnormality has occurred in the path from the communication apparatus 1 to the communication apparatus 2 in the communication line L1 at the time t1 in a state where communication is performed on the main communication line L1. As a result, the health check packet P12 from the communication device 1 transmitted after the time t1 does not reach the communication device 2, and therefore a reply to the health check packet P12 does not occur. Similarly, the health check packet P22 from the communication device 2 reaches the communication device 1 because the path from the communication device 2 to the communication device 1 is normal, but the reply to the health check packet P22 is returned to the communication device 1. 2 will not come back. Accordingly, the communication devices 1 and 2 can detect that a line abnormality has occurred.

  Thereafter, if a reply packet is not received for each specified number of times (three times in FIG. 2, and therefore for three seconds), it is determined that a line failure has occurred. In FIG. 2, since a line abnormality has occurred in the main communication line L1 and not in the subordinate communication line L2, the line abnormality is determined at times t2 and t3 when the prescribed number of times has been reached, The communication is continued by switching to the slave communication line L2.

  On the other hand, in the present invention, even if a line abnormality is once determined and the line is switched, the health check of the two communication lines L1 and L2 is continued. That is, the health check is continued regardless of whether a reply packet to the transmission packet is received. Therefore, when the routers R22 and R23 establish the detour routes L1 ′ and L1 ″ at time t4, the main communication line L1 returns with the detour route L1 ′ or L1 ″, and the communication devices 1 and 2 It is possible to detect the resolution of each line abnormality.

  Thereafter, when a reply packet is received for each specified number of times (twice in FIG. 2, and thus for 2 seconds), it is determined that the line failure has been resolved. In FIG. 2, at times t5 and t6 when the specified number of times has been reached, line restoration is determined, and the communication is continued by switching to the main communication line L1.

  FIG. 3 is a circuit block diagram showing a specific configuration example of the communication apparatuses 1 and 2. The communication devices 1 and 2 include a central processing unit 11, an oscillation circuit 12, a ROM 13 for storing programs, a RAM 14 for storing work data, a timer 15, and communication interfaces 17, 18 and 19 to be described later. Communicating via the interrupt control circuit 16 for controlling the transmission / reception interrupt and timer interrupt from the timer 15, the communication interface 17 for communicating via the main communication line L1, and the subordinate communication line L2. The communication interface 18 and the communication interface 19 for communicating with the terminal devices 5 and 6 are provided. The interrupt control circuit 16 generates an interrupt by counting the predetermined time W from the timer 15, interrupts the normal packet data, and transmits the health check packet.

  The central processing unit 11 serving as a communication control unit copies the packet data received from the terminal devices 5 and 6 via the communication interface 19, and from the communication interfaces 17 and 18 via the communication lines L1 and L2, It transmits to the communication interface communications 17 and 18 of the other communication apparatus in common. The packet data received from the other communication device via the communication lines L1 and L2 from the communication interfaces 17 and 18 is only the data of the communication line on the selected side of the communication lines L1 and L2. The data is input to the terminal devices 5 and 6 through the communication interface 19 and the received data of the communication line on the non-selection side is discarded.

  Furthermore, the central processing unit 11 transmits the health check packet from the communication interfaces 17 and 18 by the interruption by the timer 15, and from the reception result of the reply packet to the health check packet, the processing as shown in FIG. The communication lines L1 and L2 are switched.

  As described above, the communication devices 1 and 2 of the present invention are devices that selectively communicate with each other by using the duplex communication lines L1 and L2, and for switching control of the communication lines L1 and L2. When the communication interfaces 17 and 18 determine the normality / abnormality of the communication lines L1 and L2, the health check packets are transmitted from the communication apparatuses 1 and 2 to the communication lines L1 and L2, respectively, and the selected communication is performed. When no reply is obtained on the line, the central processing unit 11 switches between the communication lines L1 and L2.

  Therefore, both the communication devices 1 and 2 can check whether the communication lines L1 and L2 are arbitrarily reciprocated, so that it is easy to determine whether or not the response is a response to the health check packet from the own device using a packet number or the like Can be confirmed. As a result, even if a failure occurs in either the outgoing communication line and / or the return communication line, both communication devices can recognize this for synchronization of the switching timing. There is no need to check the contents of the data that indicates the abnormality, as in the case of checking the communication line by one-way communication from the health check packet sent from the other side, and the health check packet from your machine returns. Depending on whether or not it has been received, both the communication devices 1 and 2 can recognize the states of the communication lines L1 and L2, respectively, and can easily check the communication lines L1 and L2.

  Further, if there is a response to the health check packet from the own device, it can be determined that the failure or the like in the communication lines L1 and L2 has been solved and the communication line L1 and L2 can be used again. Is divided into a primary system and a secondary system by data transmission capacity, etc., and when the primary system is used with priority, a fault occurs in the primary system. When the obstacle is eliminated, it is possible to quickly return to the main system, which is particularly preferable.

  Further, since the central processing unit 11 switches between the communication lines L1 and L2 when a reply to the transmitted health check packet is not obtained for a predetermined number of times, intrusion of noise into the communication lines L1 and L2 The central processing unit 11 does not react excessively to an instantaneous failure such as, and can suppress undesired switching.

  Furthermore, the central processing unit 11 switches between the communication lines L1 and L2 when the switched communication line has obtained a reply to the transmitted health check packet for a predetermined number of times. Therefore, even if the communication lines L1 and L2 return from the failure, such as when the main line is switched to the slave system once, the central processing unit 11 does not change the communication line on the switched side. However, switching is delayed until the transmission / reception of the health check packet is confirmed over the predetermined number of times, and switching can be performed after the communication lines L1 and L2 are stabilized.

  The communication lines L1 and L2 are preferably dedicated lines having access restrictions from outside. According to it, in entities that operate social infrastructure such as banks, railways, electricity, gas, water, etc., communication between specific devices such as ATMs and host computers has been restricted until now, and access from outside has been restricted. It has been carried out by using a multiplexed dedicated line for business use, but by constructing the dedicated line in the IP network 3 and using the communication devices 1 and 2 described above, by adjusting the transmission cycle W of the health check packet, While ensuring the switching response required for the dedicated line, the versatility of the dedicated line can be expanded and used for other communications such as in-house telephone and data communication.

  According to the communication devices 1 and 2, although depending on the transmission period W of the health check packet and the number of times until it is determined that a failure has occurred, 3 seconds are required to switch the communication lines L1 and L2 from the occurrence of the failure as described above. For example, power companies cannot use it for system protection such as interlocking circuit breakers due to lightning strikes, but telecontrol that monitors and controls the status of substation equipment from sales offices and control stations. Further, the same IP network 3 can accommodate an opposite telephone, a general business telephone, etc., in which a control station and a substation are connected by a dedicated line.

  The communication devices 1 and 2 are realized by adding an interface board corresponding to the duplex communication lines L1 and L2 to a general personal computer and mounting the communication control program as described above in the ROM 13. be able to.

  The communication line is provided with three lines, and two of them may be used, and by selectively switching a part of the plurality of communication lines in response to a failure as described above. Anything can be used. In addition, the communication device is not limited to one-to-one communication, and may be one-to-many or many-to-many, and may be a device provided with a plurality of communication lines between communication devices that communicate with each other. That's fine. The communication line may be a general IP network as long as a plurality of communication lines are used in combination, such as an optical fiber and ADSL, and are selectively switched for use.

It is a block diagram which shows the structure of a communication system provided with the communication apparatus which concerns on one Embodiment of this invention. It is a figure which shows the health check sequence by this invention. It is a circuit block diagram which shows one specific structural example of the communication apparatus which concerns on this invention. It is a figure which shows the health check sequence by a typical prior art.

Explanation of symbols

1, 2 Communication line 3 IP network 5, 6 Terminal device 11 Central processing unit 12 Oscillation circuit 13 ROM
14 RAM
15 Timer 16 Interrupt control circuit 17, 18, 19 Communication interface H11, H12; H21, H22;... Switching hub L1, L2 , R23, R24; ... Router

Claims (6)

In a device that communicates with each other using multiplexed communication lines,
A communication control unit is provided for switching a communication line when a health check packet is transmitted from the communication interface of both communication apparatuses to each communication line and a reply to the packet cannot be obtained on the selected communication line. A communication device.   The communication apparatus according to claim 1, wherein the communication control unit switches the communication line when a reply to the transmitted health check packet is not obtained for a predetermined number of times.   The communication control unit, when switching a communication line, performs switching when the switched communication line has obtained a reply to the transmitted health check packet for a predetermined number of times. Item 3. The communication device according to Item 1 or 2.   The communication apparatus according to claim 1, wherein the communication line is a dedicated line having access restrictions from outside. In a method of communicating with each other selectively using a multiplexed communication line,
A communication control method characterized in that both communication apparatuses transmit a health check packet to each communication line and switch the communication line when a reply to the packet cannot be obtained on the selected communication line.   A communication control program for causing a communication interface of a computer to execute the communication processing procedure according to claim 5.

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