JP2020048057A - Communication device, communication line selection method and program - Google Patents

Abstract

To provide a communication device, a communication line selection method and a program, which can select a high quality line from among a plurality of accommodated lines.SOLUTION: A mobile router 100, which is a communication device which accommodates a plurality of mobile lines L1-Ln connected to a network, includes: a transmission delay time calculation unit 304 which calculates a transmission delay time channel-by-channel, based on an ICMP echo response to an ICMP echo request transmitted from each of the plurality of lines L1-Ln to a destination host in the network; a transmission delay time database 500 which threads and stores a transmission delay time with the transmission time of the ICMP echo request; a data analysis unit 600 which determines the priority of each line on the basis of the transmission delay time stored in the transmission delay time database 500; and a line selection unit 700 which, based on the priority, selects a line to be used among the plurality of lines.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a communication device, a communication line selection method, and a program.

  In recent years, in a network system, in order to improve the reliability and availability of a line, when a failure occurs in a primary line in a router accommodating a plurality of lines, the line to be used is switched to a backup line to continue communication. Redundancy has been implemented. Switching between the primary line and the backup line is generally performed in accordance with the presence or absence of an ICMP (Internet Control Message Protocol) echo request in response to an ICMP echo request (so-called alive monitoring using a ping response).

  Patent Literature 1 discloses a router device that performs communication by switching between a first line and a second line, and switches from the first line to the second line after detecting a line failure in the first line. The first protection time until the switching is performed and the second protection time until the switching from the second line to the first line after detecting the recovery of the line failure of the first line are defined as the first protection time. A technique for setting a time according to the quality state of a line is disclosed.

  In Patent Literature 1, as an example of a method of measuring a line quality state, a fluctuation of a round-trip time from transmission of an ICMP echo request to reception of a corresponding ICMP echo response is measured as jitter. Manages line quality status. In Patent Literature 1, a first protection time and a second protection time are set according to the quality state, and are applied to switching of a line when a line failure occurs / recovers.

  Patent Literature 2 discloses that monitoring data regarding the state of a transmission path is acquired from each transmission device of a network, and a time at which the monitoring data exceeds a predetermined threshold is predicted. A technique for executing network switching when a predicted time zone is entered is disclosed.

  In Patent Literature 2, the monitoring items include line quality, bandwidth used, and traffic volume of a transmission path measured by each transmission device. It also describes that the bandwidth of the network is measured using the amount of data such as an alarm transmitted from each transmission device to the network management system, and the state of the network is determined.

International Publication No. 2012/1224099 JP 2013-98706 A

  Switching from the primary line to the backup line is performed after detecting a change in the state of the primary line when the ICMP echo response of the primary line no longer arrives, so that there is a problem that a certain time delay occurs even in the case of redundancy. . Further, in a best-effort communication service using a mobile line whose line state changes more than a fixed line, it is impossible to determine whether the best line can be selected simply by the reachability of the ICMP packet.

  An object of the present disclosure is to provide a communication device, a communication line selection method, and a program capable of selecting a higher-quality line from a plurality of accommodated lines in view of the above-described problem.

  A communication device according to one aspect of the present invention is a communication device that accommodates a plurality of lines connected to a network, and includes an ICMP echo for an ICMP echo request transmitted from each of the plurality of lines to a destination host on the network. A calculating unit that calculates a transmission delay time for each line based on the response, a storage unit that stores the transmission delay time in association with a transmission time of the ICMP echo request, and a transmission unit that is stored in the storage unit. An analysis unit that determines the priority of each line based on the delay time, and a selection unit that selects a line to be used from among the plurality of lines based on the priority.

  A communication line selection method according to one aspect of the present invention is a communication line selection method for a communication device that accommodates a plurality of lines connected to a network, wherein each of the plurality of lines transmits to a destination host on the network. Based on the ICMP echo response to the ICMP echo request, the transmission delay time for each line is calculated, and the transmission delay time is stored in association with the transmission time of the ICMP echo request. A priority of each line is determined based on the priority, and a line to be used is selected from the plurality of lines based on the priority.

  A program according to an aspect of the present invention is a program for selecting a line of a communication device accommodating a plurality of lines connected to a network, wherein the ICMP transmits from each of the plurality of lines to a destination host on the network. Based on the ICMP echo response to the echo request, calculate the transmission delay time for each line, accumulate the transmission delay time in association with the transmission time of the ICMP echo request, and, based on the accumulated transmission delay time The priority of each line is determined, and the computer is caused to execute a process of selecting a line to be used among the plurality of lines based on the priority.

  According to the present invention, it is possible to provide a communication device, a communication line selection method, and a program capable of selecting a higher-quality line from a plurality of accommodated lines.

FIG. 2 is a diagram illustrating a connection example of a communication device according to an embodiment. FIG. 2 is a block diagram illustrating an example of a communication device according to an embodiment. FIG. 9 is a block diagram showing another example of the communication device according to the embodiment. FIG. 6 is a flowchart illustrating a communication line selection method according to the embodiment. It is a figure showing an example of data of transmission delay time TDTx. FIG. 9 is a diagram illustrating a comparison target in data of a transmission delay time TDTx. FIG. 9 is a diagram illustrating an example in which a priority flag FLG is set. FIG. 7 is a diagram illustrating a communication line selection method when a guard time GT is set. 6 is a time chart illustrating an example of switching communication lines. It is a flowchart explaining the communication line selection method of a comparative example.

  The present invention relates to a communication device, a communication line selection method, and a program, and more particularly, to a technology for selecting a line used for communication in a communication device that accommodates a plurality of lines connected to a network. In the present invention, the transmission delay time for each line is collected using a ping response, which is one of the functions of the ICMP (Internet Control Message Protocol), and the fluctuation of the line state is predicted based on the accumulated transmission delay time. To select a higher quality line in advance.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description and drawings are appropriately omitted and simplified for clarity of explanation. In addition, each element described in the drawing as a functional block that performs various processes can be configured by a CPU, a memory, and other lines in terms of hardware. In addition, the present invention can also be realized by causing a CPU (Central Processing Unit) to execute a computer program for an arbitrary process. Therefore, it is understood by those skilled in the art that these functional blocks can be realized in various forms by only hardware, only software, or a combination thereof, and the present invention is not limited to any of them.

  Further, the above-described program can be stored using various types of non-transitory computer readable media and supplied to a computer. Non-transitory computer readable media include tangible storage media of various types. Examples of non-transitory computer readable media are magnetic recording media (eg, flexible disk, magnetic tape, hard disk drive), magneto-optical recording media (eg, magneto-optical disk), CD-ROM (Read Only Memory), CD-R, CD-R / W, semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (Random Access Memory)). Also, the program may be supplied to the computer by various types of transitory computer readable media. Examples of transitory computer readable media include electrical signals, optical signals, and electromagnetic waves. Transitory computer readable media can provide the program to a computer via a wired communication line such as an electric wire and an optical fiber, or a wireless communication line.

  FIG. 1 is a diagram illustrating a connection example of a communication device according to an embodiment. Here, a mobile router 100 that accommodates a plurality of mobile lines L1 to Ln will be described as an example of a communication device. The mobile router 100 is a fixed installation type router that can use a plurality of mobile lines L1 to Ln provided by mobile communication carriers 1 to n as communication lines.

  As shown in FIG. 1, the mobile router 100 has a plurality of mobile line interfaces IF1 to IFn. Mobile lines L1 to Ln are connected to the interfaces IF1 to IFn, respectively. The mobile router 100 can simultaneously use a plurality of mobile lines L1 to Ln connected to a network, and perform communication by switching the line to be used. The terminal D is connected to the Internet VPN via any one of the mobile lines L1 to Ln. One of the mobile lines L1 to Ln is a primary line, and the other lines are backup lines.

  The mobile router 100 transmits an ICMP echo request from each of the communicable mobile lines L1 to Ln to the destination host TG on the network, and receives an ICMP echo response to the request. FIG. 2 shows the configuration of the mobile router 100. As shown in FIG. 2, the mobile router 100 has a transmission delay time calculation unit 304, a transmission delay time database 500, a data analysis unit 600, and a line selection unit 700.

  The transmission delay time calculator 304 calculates a transmission delay time for each of the mobile lines L1 to Ln. The transmission delay time database 500 stores the calculated transmission delay time in association with the transmission time of the ICMP echo request. The data analysis unit 600 determines the priorities of the mobile lines L1 to Ln based on the transmission delay times stored in the transmission delay time database 500. The line selection unit 700 selects a mobile line to use from the mobile lines L1 to Ln based on the priority determined by the data analysis unit 600.

  As the priority, the line with the shortest transmission delay time can be given the highest priority. As described above, the mobile router 100 according to the embodiment collects transmission delay time data, predicts a change in the line state based on the data, and can select a higher quality mobile line in advance. .

  A more specific example of the mobile router 100 will be described with reference to FIG. As shown in FIG. 3, the mobile router 100 has a router function unit 200, an ICMP control unit 300, an RTC (Real Time Clock) 400, a transmission delay time database 500, a data analysis unit 600, and a line selection unit 700. . The router function unit 200 functions as a general router that routes data input and output from the interfaces IF1 to IFn.

  The ICMP control unit 300 includes an ICMP transmitting / receiving unit 301, a host address setting unit 302, a parameter setting unit 303, and a transmission delay time calculation unit 304. The ICMP transmission / reception unit 301 generates and transmits / receives ICMP. In the embodiment, ping which is a network diagnosis program using ICMP is used. The host address setting unit 302 sets the destination host TG on the network as the destination of the ICMP echo request. The ICMP transmission / reception unit 301 transmits an ICMP echo request to the destination host TG, and receives the ICMP echo response.

  The parameter setting unit 303 sets parameters such as an ICMP echo request transmission interval, data size, and timeout time. The transmission delay time calculator 304 calculates the transmission delay time of the transmitted / received ICMP echo request / response. The RTC 400 is included in the router function unit 200 and is used to measure time. When the RTC 400 is not provided, time information may be collected from a time server on a network using NTP (Network Time Protocol).

  The transmission delay time database 500 stores the data of the transmission delay time TDTx calculated by the transmission delay time calculation unit 304 in association with the transmission time of the ICMP echo request. The transmission delay time database 500 stores a sample average AVE obtained by averaging the transmission delay time TDTx based on a predetermined condition. The transmission delay time database 500 may be provided inside the mobile router 100, or may be an external storage medium or the like connected by a network.

  The data analysis unit 600 analyzes the data stored in the transmission delay time database 500 under the conditions defined by the condition setting unit 601 and determines the priority of the mobile lines L1 to Ln. The line selection unit 700 selects and switches a mobile line to be used based on the initial priority of the mobile line set by the initial priority setting unit 701 and the priority of the mobile line determined by the data analysis unit 600. Control.

  Here, before describing the communication line selection method according to the embodiment, a communication line selection method of a comparative example using a general ping response will be described with reference to FIG. As shown in FIG. 10, in the flow of line selection based on a general ping response, first, an ICMP echo request is transmitted from a line set as a primary line to a destination host TG (step S11). Then, it is determined whether or not an ICMP echo response to the ICMP echo request has been received (step S12). In the comparative example, the state of the primary line is determined from the presence or absence of the ICMP echo response.

  When the ICMP echo response is received (Step S12, OK), the primary line is selected because there is no problem in the IP communication between the mobile router 100 and the destination host TG by the primary line (Step S13). On the other hand, if the ICMP echo response has not been received (NG in step S12), there is a problem in the IP communication between the mobile router 100 and the destination host TG using the primary line, so that the backup line is selected (step S14).

  Next, a communication line selection method according to the embodiment will be described. The operation of the mobile router 100 according to the embodiment will be described in the following four phases with reference to FIGS.

Phase 1: Data of transmission delay time of each mobile line L1 to Ln is collected.
As shown in FIG. 4, the ICMP transmission / reception unit 301 refers to the host address setting unit 302 and the parameter setting unit 303 in the ICMP control unit 300, and from each of the mobile line interfaces IF1 to IFn via the mobile lines L1 to Ln, respectively. To send an ICMP echo request to the destination host TG (step S1).

  The host address setting unit 302 of the ICMP control unit 300 sets the IP address of the destination host TG as the destination for transmitting the ICMP echo request. Note that the FQDN of the destination host TG may be set in the router function unit 200 as long as the IP address of the FQDN (Fully Qualified Domain Name) can be resolved. Further, the host address setting unit 302 sets the IP address assigned to each of the mobile line interfaces IF1 to IFn as a source of the ICMP echo request.

  As shown in FIG. 1, the destination host TG is reachable from all interfaces IF1 to IFn of the mobile router 100, and returns an ICMP echo response to the IP address assigned to each of the mobile line interfaces IF1 to IFn. Is what you can do. In the embodiment, the parameter setting unit 303 sets an ICMP sampling unit SMP, which is an ICMP echo request transmission interval, and a timeout time. Here, other parameters are not particularly limited.

  When transmitting an ICMP echo request, the ICMP transmission / reception unit 301 refers to the transmission time from the RTC 400 and transmits information linking the identification number (ID number and sequence number) of the ICMP echo request and the transmission time to the transmission delay time calculation unit. Send to 304.

  Then, it is determined whether or not an ICMP echo response to the ICMP echo request has been received (step S2). When an ICMP echo response is received (Step S2, OK), the ICMP transmitting / receiving unit 301 transmits data information of the ICMP echo response to the transmission delay time calculation unit 304 after confirming the normality of the data. When the ICMP echo response is discarded due to a data error, data indicating that the data is invalid is transmitted to the transmission delay time calculation unit 304. If the ICMP echo response has not been received within the timeout period (NG in step S2), data indicating that the data is invalid is transmitted to the transmission delay time calculation unit 304.

  Then, the transmission delay time calculation unit 304 calculates the transmission delay time of the ICMP based on the data transmitted from the ICMP transmission / reception unit 301 (step S3). The data of the calculated transmission delay time TDTx is added with a reference number REFx for each sampling unit SMP, and is stored in the transmission delay time database 500 (step S4).

  FIG. 5 shows an example of data of the transmission delay time TDTx. In the example shown in FIG. 5, data of the transmission delay time TDTx (ms) of each of the mobile lines L1 to Ln when the sampling unit SMP is 5 seconds (17280 samples per day) is shown. Each data is stored in chronological order from reference number REF000001 to reference number REF017280. The data of the transmission delay time TDTx stored in the transmission delay time database 500 is linked to the transmission time of the ICMP echo request. If the ICMP echo response has not arrived within the timeout period, or if the ICMP echo response is discarded due to a data error, "999999" indicating that the data is invalid is described.

  Returning to FIG. 4, next, data is compared based on the definition for comparing the transmission delay times TDTx of the mobile lines L1 to Ln (step S5), and the priority of the mobile lines L1 to Ln is determined (step S6). ). In the embodiment, as a definition for comparing the transmission delay time TDTx, data comparison is performed based on a sample average AVE of the transmission delay time TDTx. The mobile line with the smallest sample average AVE is given top priority. Note that the transmission delay times of the mobile lines L1 to Ln included in the date and / or time set by the condition setting unit 601 may be compared.

Phase 2: A sample average AVE of the transmission delay time TDTx is calculated.
The condition setting unit 601 of the data analysis unit 600 can set the comparison range RANG of the transmission delay time TDTx and the comparison period TERM. That is, the condition setting unit 601 is a setting unit that sets the date and time and / or the period for comparing the transmission delay times.

  The comparison range RANG is a value that determines which range of the transmission delay time TDTx among the one-day transmission delay times TDTx stored in the transmission delay time database 500 is to be used as a comparison target. For example, when the comparison range RANG = 0: 00 to 24:00, all the transmission delay times TDTx for one day are to be compared. Note that a plurality of comparison ranges RANG can be set.

  The comparison period TERM is a value that determines which day of the week is used as a comparison target. For example, when the comparison period is from Monday to Sunday, the comparison period TERM = 1 to 7 (condition: Monday to Sunday). When the comparison period is from Monday to Friday, the comparison period is “ERM = 1 to 5 (condition: Monday to Friday).

  FIG. 6 shows an example of a comparison target in the data of the transmission delay time TDTx. In the example shown in FIG. 6, a portion surrounded by a frame is a comparison target. FIG. 6 shows a comparison target when the sampling unit SMP is 5 seconds, the comparison range RANG is 6:00 to 18:00, and the comparison period TERM is 1 to 5 (conditions: Monday to Friday). Since the reference number REF004320 corresponds to 6:00 and the reference number REF012960 corresponds to 18:00, the comparison range RANG = 6: 00 to 18:00 becomes the reference number REF004320 to the reference number REF012960.

  Note that the number of transmission delay times TDTx that can be stored for one reference number REFx can be the number set in the comparison period TERM. In the example of FIG. 6, data of five (TERM: 1 to 5) transmission delay times TDTx is stored for one reference number REFx. The average value of the transmission delay time included in the date and time and the period set by the condition setting unit 601 is calculated for each of the mobile lines L1 to Ln. In the embodiment, for each of the mobile lines L1 to Ln, the average value of the five transmission delay times TDTx stored for one reference number REFx is calculated and stored as the sample average AVE in the transmission delay time database 500. .

  When a new transmission delay time TDTx is acquired as time elapses, the oldest transmission delay time TDTx is discarded, and the latest transmission delay time TDTx is registered. Thereby, the average value of the transmission delay time TDTx is recalculated. In addition, when one data of the transmission delay time TDTx cannot be obtained for one reference number REFx, the reference number REFx can be invalidated.

Phase 3: The priorities of the mobile lines L1 to Ln are determined.
As described above, in the embodiment, the mobile line with the smallest sample average AVE is given the highest priority. In the embodiment, the priority flag FLG is set to the reference number REFx of the mobile line having the smallest sample average AVE. FIG. 7 is a diagram illustrating an example in which the priority flag FLG is set. In the upper part of FIG. 7, since the data of the transmission delay time TDTx to be compared is prepared at reference numbers REF00001 to 00004, the sample average AVE of each mobile line is obtained. In the example shown in FIG. 7, the sample average AVE of the mobile line L1 is smaller than the sample average AVE of the other mobile lines. In this case, a priority flag FLG is set for the reference numbers REF00001 to 00004 of the mobile line L1.

  Immediately after the activation of the mobile router 100 or when a valid sample average AVE cannot be obtained, the initial priority setting unit 701 sets an initial priority (step S7). In the example of FIG. 7, it is assumed that the mobile line Ln is set as the mobile line with the highest priority at the initial priority. As shown in the lower part of FIG. 7, in the reference numbers REF017272 to 017280, when data of the transmission delay time TDTx of the comparison period TERM = 5 is not obtained, a priority flag is set on the mobile line Ln set by the initial priority. Can be

Phase 4: Select a primary line.
Returning to FIG. 4, next, the highest-priority mobile line selected by the priority flag FLG is selected as the primary line (S8). In a situation where the priority flag FLG is frequently switched among the plurality of mobile lines L1 to Ln, line switching occurs in a short cycle. In order to prevent this, in the embodiment, a guard time GT is used. The guard time GT is a value that, when the priority flag FLG is continuously set for one mobile line a predetermined number of times (GT times), the mobile line is switched with the highest priority. That is, the line selection unit 700 selects the mobile line when the number of times determined as the highest priority of the mobile line reaches a predetermined number.

  The condition setting unit 601 of the data analysis unit 600 can set the guard time GT. For example, when the guard time GT = 1, when the number of times that one mobile line is determined to have the highest priority reaches one, the line is switched. That is, when the guard time GT = 1, the mobile line is switched every time the priority flag FLG changes.

  FIG. 8 is a diagram illustrating a communication line selection method when the guard time GT is set. FIG. 8 shows the past priority flags FLG stored in the transmission delay time database 500 for each of the three mobile lines L1 to L3. Here, it is assumed that guard time GT = 10 is set. In this case, when the priority flag FLG is continuously set ten times from the current reference number REF (n) to the reference number REF (n + 10), the mobile line is given the highest priority.

  In the example shown in FIG. 8, referring to the past transmission delay time TDTx stored in the transmission delay time database 500, the mobile line L2 sets the flag 10 times consecutively from the reference number REF (n + 7) to REF (n + 16). Are standing. Therefore, for example, the line to be used can be switched from the mobile line L1 to the mobile line L2 at the time represented by the reference number REF (n + 7). When the number of times that the priority flag FLG continuously rises does not reach the guard time GT, the mobile line on which the priority flag FLG of the current reference number REF (n) is raised can be selected as the primary line.

  FIG. 9 shows an example of switching a mobile line in the mobile router 100 accommodating the two mobile lines L1 and L2. In FIG. 9, the horizontal axis represents time, and the vertical axis represents the variation of the sample average AVE. In the example shown in FIG. 9, it is assumed that the priority flag FLG stands on the mobile line L2 between time AB and time CD, and the priority flag FLG stands on the mobile line L1 between time BC.

  The mobile router 100 determines that the line on which the priority flag FLG is set is the highest priority mobile line, and switches the line to be used from the mobile line L2 to the mobile line L1 at time B. Similarly, at time C, the mobile line L1 is switched to the mobile line L2. As a result, it is possible to use a mobile line with less transmission delay.

  Furthermore, a function for starting an operation for switching the mobile line to be used may be provided before the time Δt to reach the time B or the time C in consideration of the time required to switch the mobile line (referred to as Δt). This makes it possible to more effectively switch to a line with a small transmission delay time.

  As described above, according to the embodiment, by utilizing the ICMP function of a general router and storing the past transmission delay time in a database for each line and holding the same, the occurrence of a failure at the current time can be achieved. Regardless of the presence or absence, it is possible to predict a change in transmission delay time that may occur in the future based on the accumulated data. This makes it possible to switch the primary line to the backup line before an event occurs if the transmission delay of the primary line is expected to increase and exceed the delay of the backup line.

  By using the communication device according to the embodiment, for example, the delay in the network was small immediately after the introduction of the network, but the number of subscribers to the mobile line carrier increased each day, and the delay in the network increased. In a network in which the delay in the network is reduced due to, for example, a high-speed communication network, the effect of utilizing a mobile line with a shorter transmission delay time can be expected without the user's awareness.

  Further, even in an environment where the communication device is installed near an event venue and the transmission delay time fluctuates irregularly greatly depending on the presence or absence of an event, the effect of utilizing a mobile line with a smaller transmission delay time can be expected. .

  Further, the communication apparatus according to the embodiment can also use a line redundancy function based on the presence or absence of a general ping response. For this reason, when the communication line selection method of the embodiment is invalid, for example, when the data of the transmission delay time is not sufficiently stored in the database immediately after the device is started, the line redundancy function based on the presence or absence of the ping response is used. It is also possible to make the line redundant by using the above method.

  It should be noted that the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist. In the embodiment, the packet length of the ICMP packet transmitted by the mobile router is not particularly limited, and the average transmission delay of the ICMP packet having the same packet length is compared. However, the present invention is not limited to this. For example, it is possible to change the ICMP packet length and determine the line quality in more detail based on the statistical information of the data distribution of the transmission delay time for each packet size.

  In addition to the transmission delay time of the ICMP packet, it is also possible to use a combination of variables such as a line standard (3G / 4G) fluctuation, an antenna level fluctuation, and a line disconnection time of a mobile line to form a line quality judgment unit. . The present invention is applicable not only to routers but also to other communication devices such as switching hub devices.

REFERENCE SIGNS LIST 100 mobile router 200 router function unit 300 ICMP control unit 301 ICMP transmission / reception unit 302 host address setting unit 303 parameter setting unit 304 transmission delay time calculation unit 400 RTC
500 transmission delay time database 501 transmission delay time data 600 data analysis unit 601 condition setting unit 700 line selection unit 701 initial priority setting unit D terminal IF1-IFn mobile line interface L1-Ln mobile line TG destination host TDTx transmission delay time SMP sampling Unit AVE Sample average RANG Comparison range TERM Comparison period FLG Priority flag GT Guard time

Claims (7)

A communication device accommodating a plurality of lines connected to a network,
A calculation unit that calculates a transmission delay time for each of the lines based on an ICMP echo response to an ICMP echo request transmitted from each of the plurality of lines to a destination host on the network;
A storage unit that stores the transmission delay time in association with the transmission time of the ICMP echo request,
An analysis unit that determines the priority of each line based on the transmission delay time stored in the storage unit,
A selection unit that selects a line to be used among the plurality of lines based on the priority,
A communication device comprising: The priority is the line with the shortest transmission delay time is the highest priority,
The communication device according to claim 1. The selection unit selects the line when the number of times the line is determined to have the highest priority reaches a predetermined number,
The communication device according to claim 2. A setting unit that sets a date and / or a period for comparing the transmission delay time,
The analysis unit determines the priority based on the transmission delay time for each line included in the date and / or period set by the setting unit,
The communication device according to claim 1. The calculation unit calculates an average value of the transmission delay time for each line included in the date and / or time period set by the setting unit,
The analysis unit determines the priority based on the average value,
The communication device according to claim 4. A method for selecting a communication line of a communication device accommodating a plurality of lines connected to a network,
Calculating a transmission delay time for each of the lines based on an ICMP echo response to an ICMP echo request transmitted to the destination host on the network from each of the plurality of lines;
The transmission delay time is stored in association with the transmission time of the ICMP echo request,
Determine the priority of each line based on the accumulated transmission delay time,
Selecting a line to be used among the plurality of lines based on the priority,
Communication line selection method. A program for selecting a line of a communication device accommodating a plurality of lines connected to a network,
Calculating a transmission delay time for each of the lines based on an ICMP echo response to an ICMP echo request transmitted to the destination host on the network from each of the plurality of lines;
The transmission delay time is stored in association with the transmission time of the ICMP echo request,
Determine the priority of each line based on the accumulated transmission delay time,
Causing a computer to execute a process of selecting a line to be used among the plurality of lines based on the priority.
program.

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