JP5505998B2 - COMMUNICATION DEVICE, ROUTE SELECTION METHOD, AND PROGRAM - Google Patents

Description

  The present invention relates to a communication device, a route selection method, and a program for selecting one communication route from a plurality of communication routes.

  In general, a communication device applied to a network has a function of selecting a communication path (network) through which data transmitted and received between a plurality of communication devices connected to the communication device passes. The communication path to be selected is selected based on the state of the communication path. For example, when it is determined that a failure has occurred in the currently selected communication path, or when it is determined that the communication quality has deteriorated, another communication path is selected, and the communication path through which the data passes is currently selected. The communication path that has been set is switched to another communication path.

  As means for determining the occurrence of a failure in such a communication path, for example, a confirmation message for confirming the state of the path such as an ICMP (Internet Control Message Protocol) packet and a reply message for the confirmation message are used. When a confirmation message is transmitted and a reply message for the confirmation message is not received, it is determined that a failure has occurred in the communication path.

  When a reply message for the transmitted confirmation message is not received, it is common to use a predetermined number of protection steps (threshold number threshold) instead of immediately switching the communication path.

  Here, when this threshold value is small, when the quality of the main communication route (main route) is intermittently deteriorated, switching between the main route and the detour route and switching back and forth are frequently performed. There is a risk that. On the other hand, if this threshold is a large value, it may take a long time to switch back from the detour route when the main route recovers from a sudden abnormality.

  Therefore, it is determined that the quality of the main route has sufficiently recovered based on the response time from when the confirmation message is transmitted until the reply message is received, and the margin value indicating the state of quality deterioration is reduced. Thus, a technique for reducing the delay in switching back is considered (for example, see Patent Document 1).

JP2012-169910A

  However, in the above-described technique, it is necessary to set a response threshold value to be compared with the response time in advance when making the determination, which is troublesome. The response threshold needs to consider conditions such as the type of main route.

  The objective of this invention is providing the communication apparatus, route selection method, and program which solve the subject mentioned above.

The communication device of the present invention
A communication device that is connected to a plurality of communication paths and performs communication by selecting one of the plurality of communication paths.
A path state confirmation unit that transmits a path confirmation request signal for confirming a state of the first communication path among the plurality of communication paths, and receives a response signal to the transmitted path confirmation request signal;
A timer for measuring a response time from when the route state confirmation unit transmits the route confirmation request signal to receiving the response signal to the route confirmation request signal;
A normal counter that counts the continuous number of times that the route state confirmation unit has received the response signal in response to the route confirmation request signal;
An abnormality counter that counts the number of times that the route state confirmation unit has not received the response signal in response to the route confirmation request signal;
In order to calculate the initial value of the abnormality counter when the route state confirmation unit does not receive the response signal to the route confirmation request signal after receiving the response signal to the route confirmation request signal The initial value is calculated based on the correction value and the normal counter value, the abnormal counter value is counted from the calculated initial value, and the counted abnormal counter value is equal to or greater than a preset switching threshold value. The communication path is instructed to switch the communication path from the first communication path to a second communication path other than the first communication path, and the path status confirmation unit responds to the path confirmation request signal The average response time calculated based on the response time measured by the timer when the response signal is received with respect to the route confirmation request signal after not receiving the response signal. A response threshold value is calculated based on a minimum response time that is the smallest of the response times, and the correction value is calculated using the response threshold value, the response time measured by the timer, the current correction value, and the current abnormality counter. And when the value of the normal counter is equal to or greater than a value obtained by adding the calculated correction value and a preset switchback threshold, the communication path is changed from the second communication path to the A state calculating unit that gives an instruction to switch back to the first communication path;
And a route selection unit that selects either the first communication route or the second communication route as the communication route based on an instruction from the state calculation unit.

Further, the route selection method of the present invention includes:
A path selection method for selecting a communication path through which a communication device connected to a plurality of communication paths performs communication from the plurality of communication paths,
A process of transmitting a route confirmation request signal for confirming the state of the first communication route among the plurality of communication routes;
Processing for confirming whether or not a response signal to the transmitted route confirmation request signal has been received;
Processing for measuring a response time from transmission of the route confirmation request signal to reception of the response signal to the route confirmation request signal;
After receiving the response signal for the route confirmation request signal, if the response signal is not received for the route confirmation request signal, the response signal is not received for the route confirmation request signal Based on a correction value for calculating an initial value at the time of counting the first number of consecutive times and a second number of times of receiving the response signal in response to the route confirmation request signal. A process for calculating the initial value;
A process of counting the first number of times from the calculated initial value;
A process of comparing the counted first number with a preset switching threshold;
A process of switching the communication path from the first communication path to a second communication path other than the first communication path when the counted first number is equal to or greater than the switching threshold; and the path confirmation request signal When the response signal is received with respect to the route confirmation request signal after not receiving the response signal, the average response time calculated based on the measured response time and the minimum of the response times A process for calculating a response threshold based on the minimum response time,
After calculating the response threshold, the correction value is calculated based on the response threshold, the measured response time, the current correction value, and the current first number of times,
A process of comparing a value obtained by adding the calculated correction value and a preset switchback threshold to the second number of times;
When the second number of times is equal to or greater than a value obtained by adding the calculated correction value and the switchback threshold, a process of switching the communication path from the second communication path to the first communication path is performed. Do.

The program of the present invention is
A program that is connected to a plurality of communication paths and that is executed by a communication device that performs communication by selecting one communication path from the plurality of communication paths,
A procedure for transmitting a route confirmation request signal for confirming the state of the first communication route among the plurality of communication routes;
A procedure for confirming whether or not a response signal to the transmitted route confirmation request signal has been received;
A procedure for measuring a response time from transmission of the route confirmation request signal to reception of the response signal to the route confirmation request signal;
After receiving the response signal for the route confirmation request signal, if the response signal is not received for the route confirmation request signal, the response signal is not received for the route confirmation request signal Based on a correction value for calculating an initial value at the time of counting the first number of consecutive times and a second number of times of receiving the response signal in response to the route confirmation request signal. A procedure for calculating the initial value;
A procedure of counting the first number of times from the calculated initial value;
Comparing the counted first number with a preset switching threshold;
A procedure for switching the communication path from the first communication path to a second communication path other than the first communication path when the counted first number is equal to or greater than the switching threshold; and the path confirmation request signal When the response signal is received with respect to the route confirmation request signal after not receiving the response signal, the average response time calculated based on the measured response time and the minimum of the response times A procedure for calculating a response threshold based on the minimum response time,
After calculating the response threshold, calculating the correction value based on the response threshold, the measured response time, the current correction value, and the current first number of times,
A step of comparing the calculated correction value and a value obtained by adding a preset switchback threshold with the second number of times;
A step of switching back the communication path from the second communication path to the first communication path when the second number of times is equal to or greater than a value obtained by adding the calculated correction value and the switchback threshold. Let it run.

  As described above, according to the present invention, it is possible to easily determine whether the communication path is switched back.

It is a figure which shows one Embodiment of the communication apparatus of this invention. 2 is a flowchart for explaining a route selection method when a response signal to a route confirmation request signal is not received in the form shown in FIG. 1. 4 is a flowchart for explaining a route selection method when a response signal to a route confirmation request signal is received in the form shown in FIG. 1. It is a flowchart for demonstrating the detail of the process of step S31. It is a flowchart for demonstrating the detail of the process of step S32.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing an embodiment of a communication apparatus according to the present invention.

  As shown in FIG. 1, the present embodiment includes communication devices 1-1 and 1-2, a main route 2, a detour route 3, and communication terminals 4-1 and 4-2. In the form shown in FIG. 1, the case where there are two communication paths has been described as an example, but there may be three or more.

  The communication apparatuses 1-1 and 1-2 select a communication path through which data such as an IP (Internet Protocol) packet transmitted and received between the communication terminal 4-1 and the communication terminal 4-2 passes.

  The main path 2 connects the communication device 1-1 and the communication device 1-2, and is normally set to pass data transmitted and received between the communication terminal 4-1 and the communication terminal 4-2. It is a communication path.

  The detour path 3 is one of the communication paths that connect the communication device 1-1 and the communication device 1-2 and through which data transmitted and received between the communication terminal 4-1 and the communication terminal 4-2 passes. . The detour path 3 is a second communication path that is selected when a failure occurs in the main path 2.

  The communication terminals 4-1 and 4-2 are communication devices connected to the communication devices 1-1 and 1-2, respectively.

  Further, the communication device 1-1 is provided with a route state confirmation unit 11, a state calculation unit 12, a route selection unit 13, a normal counter 14, an abnormality counter 15, and a timer 16.

  The route state confirmation unit 11 confirms the state of the main route 2. Specifically, the route state confirmation unit 11 transmits a route confirmation request signal to the communication device 1-2 via the main route 2, and based on whether a response signal to the transmitted route confirmation request signal is received. Whether or not a failure has occurred in the main route 2 is confirmed. In the present embodiment, an example will be described in which ICMP ECHO_REQUEST of ICMP (Internet Control Message Protocol) is used as the route confirmation request signal and ICMP ECHO_REPLY is used as the response signal.

  The state calculation unit 12 determines switching / switching back of the communication route based on the state of the main route 2 confirmed by the route state confirmation unit 11, and instructs the route selection unit 13 of the determined result. Here, switching the communication path indicates changing the communication path from the main path 2 to the detour path 3. Further, switching back a communication path indicates changing the communication path from the bypass path 3 to the main path 2.

  In addition, after receiving a response signal for the route confirmation request signal transmitted by the route state confirmation unit 11, the state calculation unit 12 receives the response signal for the route confirmation request signal. The initial value is calculated based on the correction value (margin value) for calculating the initial value and the value of the normal counter 14. Details of this calculation method will be described later. Further, after calculating the initial value, the state calculating unit 12 causes the abnormality counter 15 to count from the calculated initial value. Further, the state calculation unit 12 compares the value counted by the abnormality counter 15 with a preset switching threshold value. In addition, when the value counted by the abnormality counter 15 is equal to or greater than the switching threshold, the state calculation unit 12 instructs the route selection unit 13 to switch the communication route from the main route 2 to the detour route 3.

  When the state calculation unit 12 does not receive a response signal to the route confirmation request signal transmitted by the route state confirmation unit 11 and then receives a response signal to the route confirmation request signal, the timer 16 performs measurement. An average response time is calculated based on the response time. Specifically, the state calculation unit 12 calculates a value obtained by dividing a value obtained by adding the current average response time and the response time measured by the timer 16 by 2 as a new average response time. Further, the state calculation unit 12 calculates a response threshold value based on the calculated average response time and the minimum response time that is the minimum of the response times. Specifically, a value obtained by subtracting the minimum response time from a value obtained by multiplying the calculated average response time by 2 is calculated as a response threshold. In addition, after calculating the response threshold, the state calculation unit 12 calculates the above-described correction value (margin value) by using the calculated response threshold, the response time measured by the timer 16, the current correction value, and the current abnormality counter 15 value. Based on and. In addition, the state calculation unit 12 compares the value obtained by adding the calculated correction value and a preset switchback threshold with the value of the normal counter 14. In addition, when the value of the normal counter 14 is equal to or greater than the value obtained by adding the calculated correction value and the switchback threshold, the state calculation unit 12 instructs to switch the communication path from the bypass path 3 to the main path 2. .

  Further, when the value of the abnormality counter 15 is equal to or greater than the switching threshold, the state calculation unit 12 sets “0” as a correction value for calculating the initial value of the abnormality counter 15.

  In addition, the state calculation unit 12 switches the response time measured by the timer 16 to be shorter than the response threshold, the correction value is larger than “0”, and the value of the abnormality counter 15 is larger than “0”. If it is less than the threshold, 1 is subtracted from the correction value. Then, the state calculating unit 12 sets a value obtained by dividing the correction value obtained by subtracting 1 and the value of the abnormality counter 15 by 2 as a correction value for calculating the initial value of the abnormality counter 15.

  Further, the state calculation unit 12 resets the value of the abnormality counter 15 after calculating the correction value.

  Further, the state calculation unit 12 calculates a value obtained by subtracting the value of the normal counter 14 from the value obtained by adding the correction value and 1 as an initial value, calculates the initial value, and then resets the value of the normal counter 14. .

  The route selection unit 13 selects either the main route 2 or the detour route 3 as a communication route based on an instruction from the state calculation unit 12. That is, the route selection unit 13 performs switching of the communication route (from the main route 2 to the detour route 3) / switching back (from the detour route 3 to the main route 2) based on the instruction from the state calculation unit 12.

  The normal counter 14 counts the number of consecutive times (second number) of receiving a response signal to the route confirmation request signal transmitted by the route state confirmation unit 11. That is, when a response signal to the route confirmation request signal transmitted by the route state confirmation unit 11 is received after a state in which a response signal to the route confirmation request signal transmitted by the route state confirmation unit 11 is not received, the route confirmation request signal Until the response signal is not received, the number of receptions of the response signal for the route confirmation request signal transmitted by the route state confirmation unit 11 is counted. Further, the normal counter 14 notifies the state calculation unit 12 of a count value that is the number of times counted.

  The abnormality counter 15 counts the number of consecutive times (first number) that has not received a response signal to the route confirmation request signal transmitted by the route state confirmation unit 11. That is, if a response signal to the route confirmation request signal transmitted by the route state confirmation unit 11 is not received after the response signal to the route confirmation request signal transmitted by the route state confirmation unit 11 is received, the route confirmation request signal is next received. Until the response signal is received, the number of transmissions of the route confirmation request signal transmitted by the route state confirmation unit 11 is counted. Further, the abnormality counter 15 notifies the state calculation unit 12 of a count value that is the number of times counted.

  The timer 16 measures a response time from when the route state confirmation unit 11 transmits a route confirmation request signal until it receives a response signal to the route confirmation request signal. In addition, the timer 16 notifies the state calculation unit 12 of the measured response time.

  Note that the communication device 1-2 has the same configuration as the communication device 1-1.

  Below, the route selection method in the form shown in FIG. 1 will be described. Here, each time the route state confirmation unit 11 transmits a route confirmation request signal, the timer 16 starts measuring the response time.

  FIG. 2 is a flowchart for explaining a route selection method when a response signal to the route confirmation request signal is not received in the form shown in FIG.

  There is no response within a predetermined time with respect to ICMP ECHO_REQUEST transmitted from the route state confirmation unit 11 to the communication device 1-2 via the main route 2, that is, ICMP ECHO_REPLY is not received by the route state confirmation unit 11. If judged (step S20), the initial value of the abnormality counter 15 is set by the state calculation part 12 (step S21).

  Here, the determination in step S20 may be performed using the timer 16 that is activated when ICMP ECHO_REQUEST is transmitted. This timer 16 is reset when ICMP ECHO_REPLY is received. Further, when ICMP ECHO_REQUEST is transmitted but ICMP ECHO_REPLY is not received, it is determined that “ICMP ECHO_REPLY is not received” when a predetermined time has elapsed.

  Here, the process of step S21 will be specifically described.

  If it is determined in step S20 that ICMP ECHO_REPLY is not received by the path status confirmation unit 11, the path selection unit 13 determines whether or not the currently selected communication path is the main path 2 (step S211). ).

  If it is determined that the currently selected communication path is the main path 2, the state calculation unit 12 determines whether or not the value of the abnormality counter 15 is “0” (step S212).

  When it is determined that the value of the abnormality counter 15 is “0”, the state calculation unit 12 determines whether the value of the normal counter 14 is smaller than “(margin value) +1” (step S213). This “margin value” is a correction value for calculating the initial value of the abnormality counter 15, and the calculation method will be described later.

  When it is determined that the value of the normal counter 14 is smaller than “(margin value) +1”, the state calculation unit 12 sets the value of the abnormality counter 15 to “(margin value) + 1− (value of the normal counter 14)”. (Step S214). This value becomes the initial value of the abnormality counter 15.

  This margin value is a value representing the intermittent quality degradation of the main path 2. By using this margin value, it is included in the abnormality counter 15 and initialized so that switching to the detour path 3 can be performed even when the quality degradation of the main path 2 occurs intermittently.

  Thereafter, the value of the normal counter 14 is reset to “0” by the state calculation unit 12 (step S22). If “No” in step S211, “No” in step S212, or “No” in step S213, the process of step S22 is performed.

  In addition, the value of the abnormality counter 15 is incremented by one by the state calculation unit 12 (step S23).

  Then, it is judged by the state calculation part 12 whether the value of the abnormality counter 15 is more than the preset switching threshold value (step S24).

  When it is determined that the value of the abnormality counter 15 is equal to or greater than the switching threshold, an instruction to switch the communication route from the main route 2 to the detour route 3 is issued from the state calculation unit 12 to the route selection unit 13. Then, the route selection unit 13 instructed to switch the communication route from the main route 2 to the bypass route 3 switches the communication route from the main route 2 to the bypass route 3 (step S25).

  FIG. 3 is a flowchart for explaining a route selection method when a response signal to the route confirmation request signal is received in the form shown in FIG.

  When there is a response to the ICMP ECHO_REQUEST transmitted from the path state confirmation unit 11, that is, when ICMP ECHO_REPLY is received by the path state confirmation unit 11 (step S30), the communication path is changed from the detour path 3 to the main path 2. The state calculation unit 12 updates the margin value for switching back (steps S31 to S32).

  The process of step S31 is a margin value update process based on the ICMP ECHO_REPLY reception speed. Further, the process in step S32 is a margin value update process based on whether or not ICMP ECHO_REPLY is received.

  Details of the process will be described below in step S31.

  FIG. 4 is a flowchart for explaining details of the processing in step S31.

  When ICMP ECHO_REPLY is received by the path state confirmation unit 11, the response time measured by the timer 16 until the ICMP ECHO_REPLY is received after the ICMP ECHO_REQUEST is transmitted from the path state confirmation unit 11 and the response time thus far The state response unit 12 compares the minimum response time that is the smallest of the two (step S311). When the response time measured by the timer 16 is shorter than the minimum response time, the state calculation unit 12 updates the minimum response time to the value of the response time (step S312). That is, the response time that is the minimum of the response time is always held as the minimum response time by the state calculation unit 12. When there is no response time data held (for example, when measuring the first response time), the minimum response time is set to a certain value in advance.

  Further, the state calculation unit 12 updates a value obtained by dividing the current average response time and the response time measured by the timer 16 by 2 as an average response time (average response time = (average response time + Response time) ÷ 2) (step S313). If the response time measured by the timer 16 is equal to or longer than the minimum response time in step S311, the process in step S312 is not performed and the process in step S313 is performed.

  Subsequently, a response threshold value is calculated by the state calculation unit 12 based on the average response time and the minimum response time (step S314). Specifically, the state calculation unit 12 calculates a value obtained by subtracting the minimum response time from the value obtained by multiplying the average response time by 2 as a response threshold (response threshold = average response time × 2−minimum response time).

  Subsequently, the response time measured by the timer 16 and the response threshold are compared by the state calculation unit 12 (step S315).

  If the response time is shorter than the response threshold, the state calculation unit 12 determines whether or not the current margin value is larger than “0” (step S316).

  When it is determined that the current margin value is larger than “0”, the state calculation unit 12 updates the margin value to a value obtained by subtracting “1” from the current margin value (step S317). . Thereafter, the process of step S32 is performed.

  If the response time is not shorter than the response threshold in step S315, or if it is determined in step S316 that the current margin value is not greater than “0”, the process of step S32 is performed. Is called.

  Details of step S32 will be described below.

  FIG. 5 is a flowchart for explaining details of the process in step S32.

  First, the state calculation unit 12 determines whether or not the value of the abnormality counter 15 is larger than “0” (step S321).

  When it is determined that the value of the abnormality counter 15 is larger than “0”, the state calculation unit 12 determines whether or not the value of the abnormality counter 15 is equal to or greater than a preset switching threshold value (step S12). S322).

  When it is determined that the value of the abnormality counter 15 is greater than or equal to the switching threshold, the margin value is reset to “0” by the state calculation unit 12 (step S323). This margin value is used for setting the initial value of the abnormality counter 15 described above. As described above, when it is determined that the value of the abnormality counter 15 is equal to or greater than the switching threshold, it is determined that a sudden abnormality has occurred in the main path 2 and the margin value is set to “0”.

  On the other hand, when it is determined in step S322 that the value of the abnormality counter 15 is not greater than or equal to the switching threshold, the margin value is calculated (updated) by the state calculation unit 12 based on the current margin value and the current value of the abnormality counter 15. (Step S324). A specific calculation method is “(margin value) = ((current margin value) + (value of abnormality counter 15)) / 2”. Here, the fraction (rounded down) is rounded up. As described above, when it is determined that the value of the abnormality counter 15 is not equal to or higher than the switching threshold, it is determined that the quality of the main path 2 is intermittently decreased, and the margin value is recalculated and updated. Yes.

  Thereafter, the state calculation unit 12 increments (counts) the value of the normal counter 14 by one (step S33).

  If it is determined in step S321 that the value of the abnormality counter 15 is “0”, the process of step S33 is performed.

  Further, the value of the abnormality counter 15 is reset to “0” by the state calculation unit 12 (step S34).

  Then, the state calculation unit 12 determines whether or not the value of the normal counter 14 is equal to or greater than a value obtained by adding a preset switchback threshold and a margin value (step S35).

  If it is determined in step S35 that the value of the normal counter 14 is equal to or greater than the value obtained by adding the switchback threshold and the margin value, the state calculation unit 12 notifies the route selection unit 13 of a communication path switchback instruction. Then, the communication path is switched back from the detour path 3 to the main path 2 by the path selection unit 13 (step S36). Then, the margin value is reset to “0” by the state calculation unit 12 (step S37). By including a margin value in determining whether to switch back the communication path from the bypass path 3 to the main path 2, switching back of the communication path when the quality of the main path 2 is intermittently reduced is suppressed. .

  As described above, in the present invention, the response threshold value is updated according to the response time, so that it is possible to easily determine whether the communication path is switched back.

  Further, as a method of calculating the response threshold, (response threshold = average response time + (average response time−minimum response time) × n) may be used using a weighting coefficient (n). Further, (average response time = total response time / total number of responses) may be used as a method for calculating the average response time.

  Further, in addition to using ICMP ECHO_REQUEST / ECHO_REPLY for failure monitoring, a unique keepalive may be used.

  The processing performed by each component provided in the communication device 1-1 described above may be performed by a logic circuit produced according to the purpose. Further, a computer program (hereinafter referred to as a program) in which processing contents are described as a procedure is recorded on a recording medium readable by the communication apparatus 1-1, and the program recorded on the recording medium is stored in the communication apparatus 1-1. It may be read and executed. The recording medium readable by the communication device 1-1 includes a transfer medium such as a floppy (registered trademark) disk, a magneto-optical disk, a DVD, and a CD, a ROM built in the communication device 1-1, It refers to a memory such as a RAM or an HDD. The program recorded on this recording medium is read by a CPU (not shown) provided in the communication device 1-1, and the same processing as described above is performed under the control of the CPU. Here, the CPU operates as a computer that executes a program read from a recording medium on which the program is recorded.

A part or all of the above embodiment can be described as in the following supplementary notes, but is not limited thereto.
(Supplementary Note 1) A communication device that is connected to a plurality of communication paths and performs communication by selecting one of the plurality of communication paths.
A path state confirmation unit that transmits a path confirmation request signal for confirming a state of the first communication path among the plurality of communication paths, and receives a response signal to the transmitted path confirmation request signal;
A timer for measuring a response time from when the route state confirmation unit transmits the route confirmation request signal to receiving the response signal to the route confirmation request signal;
A normal counter that counts the continuous number of times that the route state confirmation unit has received the response signal in response to the route confirmation request signal;
An abnormality counter that counts the number of times that the route state confirmation unit has not received the response signal in response to the route confirmation request signal;
In order to calculate the initial value of the abnormality counter when the route state confirmation unit does not receive the response signal to the route confirmation request signal after receiving the response signal to the route confirmation request signal The initial value is calculated based on the correction value and the normal counter value, the abnormal counter value is counted from the calculated initial value, and the counted abnormal counter value is equal to or greater than a preset switching threshold value. The communication path is instructed to switch the communication path from the first communication path to a second communication path other than the first communication path, and the path status confirmation unit responds to the path confirmation request signal The average response time calculated based on the response time measured by the timer when the response signal is received with respect to the route confirmation request signal after not receiving the response signal. A response threshold value is calculated based on a minimum response time that is the smallest of the response times, and the correction value is calculated using the response threshold value, the response time measured by the timer, the current correction value, and the current abnormality counter. And when the value of the normal counter is equal to or greater than a value obtained by adding the calculated correction value and a preset switchback threshold, the communication path is changed from the second communication path to the A state calculating unit that gives an instruction to switch back to the first communication path;
A communication apparatus comprising: a route selection unit that selects either the first communication route or the second communication route as the communication route based on an instruction from the state calculation unit.
(Supplementary Note 2) The state calculation unit calculates a value obtained by dividing the current average response time and the response time by 2 as an average response time, and multiplies the calculated average response time by 2. The communication apparatus according to appendix 1, wherein a value obtained by subtracting the minimum response time from a value is calculated as the response threshold.
(Supplementary Note 3) When the value of the abnormality counter is equal to or greater than the switching threshold, the state calculation unit sets 0 as a correction value for calculating the initial value of the abnormality counter, and the response time is shorter than the response threshold. If the correction value is short and the correction value is greater than 0, and the value of the abnormality counter is greater than 0 and less than the switching threshold, 1 is subtracted from the correction value, and the correction value obtained by subtracting 1 The communication apparatus according to Supplementary Note 1 or Supplementary Note 2, wherein a value obtained by dividing a value obtained by adding the value of the abnormality counter and the value obtained by dividing the value by 2 is used as a correction value for calculating an initial value of the abnormality counter.
(Additional remark 4) The said state calculation part resets the value of the said abnormality counter, after calculating the said correction value, The communication apparatus of any one of Additional remark 1 to 3 characterized by the above-mentioned.
(Supplementary Note 5) The state calculation unit calculates a value obtained by subtracting the value of the normal counter from a value obtained by adding the correction value and 1 as the initial value, and after calculating the initial value, The communication device according to any one of appendices 1 to 4, wherein the value is reset.
(Additional remark 6) It is the path | route selection method which selects the communication path | route which the communication apparatus connected with the several communication path | route communicates from among the said some communication path | route,
A process of transmitting a route confirmation request signal for confirming the state of the first communication route among the plurality of communication routes;
Processing for confirming whether or not a response signal to the transmitted route confirmation request signal has been received;
Processing for measuring a response time from transmission of the route confirmation request signal to reception of the response signal to the route confirmation request signal;
After receiving the response signal for the route confirmation request signal, if the response signal is not received for the route confirmation request signal, the response signal is not received for the route confirmation request signal Based on a correction value for calculating an initial value at the time of counting the first number of consecutive times and a second number of times of receiving the response signal in response to the route confirmation request signal. A process for calculating the initial value;
A process of counting the first number of times from the calculated initial value;
A process of comparing the counted first number with a preset switching threshold;
A process of switching the communication path from the first communication path to a second communication path other than the first communication path when the counted first number is equal to or greater than the switching threshold; and the path confirmation request signal When the response signal is received with respect to the route confirmation request signal after not receiving the response signal, the average response time calculated based on the measured response time and the minimum of the response times A process for calculating a response threshold based on the minimum response time,
After calculating the response threshold, the correction value is calculated based on the response threshold, the measured response time, the current correction value, and the current first number of times,
A process of comparing a value obtained by adding the calculated correction value and a preset switchback threshold to the second number of times;
When the second number of times is equal to or greater than a value obtained by adding the calculated correction value and the switchback threshold, a process of switching the communication path from the second communication path to the first communication path is performed. The route selection method to perform.
(Supplementary Note 7) A communication device that is connected to a plurality of communication paths and selects one communication path among the plurality of communication paths to perform communication.
A procedure for transmitting a route confirmation request signal for confirming the state of the first communication route among the plurality of communication routes;
A procedure for confirming whether or not a response signal to the transmitted route confirmation request signal has been received;
A procedure for measuring a response time from transmission of the route confirmation request signal to reception of the response signal to the route confirmation request signal;
After receiving the response signal for the route confirmation request signal, if the response signal is not received for the route confirmation request signal, the response signal is not received for the route confirmation request signal Based on a correction value for calculating an initial value at the time of counting the first number of consecutive times and a second number of times of receiving the response signal in response to the route confirmation request signal. A procedure for calculating the initial value;
A procedure of counting the first number of times from the calculated initial value;
Comparing the counted first number with a preset switching threshold;
A procedure for switching the communication path from the first communication path to a second communication path other than the first communication path when the counted first number is equal to or greater than the switching threshold; and the path confirmation request signal When the response signal is received with respect to the route confirmation request signal after not receiving the response signal, the average response time calculated based on the measured response time and the minimum of the response times A procedure for calculating a response threshold based on the minimum response time,
After calculating the response threshold, calculating the correction value based on the response threshold, the measured response time, the current correction value, and the current first number of times,
A step of comparing the calculated correction value and a value obtained by adding a preset switchback threshold with the second number of times;
A step of switching back the communication path from the second communication path to the first communication path when the second number of times is equal to or greater than a value obtained by adding the calculated correction value and the switchback threshold. A program to be executed.

1-1, 1-2 Communication device 2 Main route 3 Detour route 4-1, 4-2 Communication terminal 11 Route state confirmation unit 12 State calculation unit 13 Route selection unit 14 Normal counter 15 Abnormal counter 16 Timer

Claims (7)

A communication device that is connected to a plurality of communication paths and performs communication by selecting one of the plurality of communication paths.
A path state confirmation unit that transmits a path confirmation request signal for confirming a state of the first communication path among the plurality of communication paths, and receives a response signal to the transmitted path confirmation request signal;
A timer for measuring a response time from when the route state confirmation unit transmits the route confirmation request signal to receiving the response signal to the route confirmation request signal;
A normal counter that counts the continuous number of times that the route state confirmation unit has received the response signal in response to the route confirmation request signal;
An abnormality counter that counts the number of times that the route state confirmation unit has not received the response signal in response to the route confirmation request signal;
In order to calculate the initial value of the abnormality counter when the route state confirmation unit does not receive the response signal to the route confirmation request signal after receiving the response signal to the route confirmation request signal The initial value is calculated based on the correction value and the normal counter value, the abnormal counter value is counted from the calculated initial value, and the counted abnormal counter value is equal to or greater than a preset switching threshold value. The communication path is instructed to switch the communication path from the first communication path to a second communication path other than the first communication path, and the path status confirmation unit responds to the path confirmation request signal The average response time calculated based on the response time measured by the timer when the response signal is received with respect to the route confirmation request signal after not receiving the response signal. A response threshold value is calculated based on a minimum response time that is the smallest of the response times, and the correction value is calculated using the response threshold value, the response time measured by the timer, the current correction value, and the current abnormality counter. And when the value of the normal counter is equal to or greater than a value obtained by adding the calculated correction value and a preset switchback threshold, the communication path is changed from the second communication path to the A state calculating unit that gives an instruction to switch back to the first communication path;
A communication apparatus comprising: a route selection unit that selects either the first communication route or the second communication route as the communication route based on an instruction from the state calculation unit. The communication device according to claim 1,
The state calculation unit calculates a value obtained by dividing a value obtained by adding the current average response time and the response time by 2 as an average response time, and calculates the minimum response value by multiplying the calculated average response time by 2 A communication apparatus that calculates a value obtained by subtracting a response time as the response threshold. The communication device according to claim 1 or 2,
When the value of the abnormality counter is greater than or equal to the switching threshold, the state calculation unit sets 0 as a correction value for calculating the initial value of the abnormality counter, the response time is shorter than the response threshold, and the When the correction value is greater than 0 and the value of the abnormality counter is greater than 0 and less than the switching threshold, 1 is subtracted from the correction value, the correction value obtained by subtracting 1 and the abnormality counter A communication device characterized in that a value obtained by dividing the value obtained by dividing the value by 2 by 2 is used as a correction value for calculating an initial value of the abnormality counter. The communication apparatus according to any one of claims 1 to 3,
The state calculation unit resets the value of the abnormality counter after calculating the correction value. The communication device according to any one of claims 1 to 4,
The state calculation unit calculates a value obtained by subtracting the value of the normal counter from a value obtained by adding the correction value and 1 as the initial value, and after calculating the initial value, resets the value of the normal counter A communication device. A path selection method for selecting a communication path through which a communication device connected to a plurality of communication paths performs communication from the plurality of communication paths,
A process of transmitting a route confirmation request signal for confirming the state of the first communication route among the plurality of communication routes;
Processing for confirming whether or not a response signal to the transmitted route confirmation request signal has been received;
Processing for measuring a response time from transmission of the route confirmation request signal to reception of the response signal to the route confirmation request signal;
After receiving the response signal for the route confirmation request signal, if the response signal is not received for the route confirmation request signal, the response signal is not received for the route confirmation request signal Based on a correction value for calculating an initial value at the time of counting the first number of consecutive times and a second number of times of receiving the response signal in response to the route confirmation request signal. A process for calculating the initial value;
A process of counting the first number of times from the calculated initial value;
A process of comparing the counted first number with a preset switching threshold;
A process of switching the communication path from the first communication path to a second communication path other than the first communication path when the counted first number is equal to or greater than the switching threshold; and the path confirmation request signal When the response signal is received with respect to the route confirmation request signal after not receiving the response signal, the average response time calculated based on the measured response time and the minimum of the response times A process for calculating a response threshold based on the minimum response time,
After calculating the response threshold, the correction value is calculated based on the response threshold, the measured response time, the current correction value, and the current first number of times,
A process of comparing a value obtained by adding the calculated correction value and a preset switchback threshold to the second number of times;
When the second number of times is equal to or greater than a value obtained by adding the calculated correction value and the switchback threshold, a process of switching the communication path from the second communication path to the first communication path is performed. The route selection method to perform. A communication device that is connected to a plurality of communication paths and selects one communication path from the plurality of communication paths to perform communication.
A procedure for transmitting a route confirmation request signal for confirming the state of the first communication route among the plurality of communication routes;
A procedure for confirming whether or not a response signal to the transmitted route confirmation request signal has been received;
A procedure for measuring a response time from transmission of the route confirmation request signal to reception of the response signal to the route confirmation request signal;
After receiving the response signal for the route confirmation request signal, if the response signal is not received for the route confirmation request signal, the response signal is not received for the route confirmation request signal Based on a correction value for calculating an initial value at the time of counting the first number of consecutive times and a second number of times of receiving the response signal in response to the route confirmation request signal. A procedure for calculating the initial value;
A procedure of counting the first number of times from the calculated initial value;
Comparing the counted first number with a preset switching threshold;
A procedure for switching the communication path from the first communication path to a second communication path other than the first communication path when the counted first number is equal to or greater than the switching threshold; and the path confirmation request signal When the response signal is received with respect to the route confirmation request signal after not receiving the response signal, the average response time calculated based on the measured response time and the minimum of the response times A procedure for calculating a response threshold based on the minimum response time,
After calculating the response threshold, calculating the correction value based on the response threshold, the measured response time, the current correction value, and the current first number of times,
A step of comparing the calculated correction value and a value obtained by adding a preset switchback threshold with the second number of times;
A step of switching back the communication path from the second communication path to the first communication path when the second number of times is equal to or greater than a value obtained by adding the calculated correction value and the switchback threshold. A program to be executed.

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