WO2015155816A1

WO2015155816A1 - Network device and communication method

Info

Publication number: WO2015155816A1
Application number: PCT/JP2014/060076
Authority: WO
Inventors: 徳寿阿久津
Original assignee: 株式会社日立製作所
Priority date: 2014-04-07
Filing date: 2014-04-07
Publication date: 2015-10-15

Abstract

　The purpose of the present invention is to provide a technique with which it is possible to perform communication in an appropriate operation mode even when a communication cable is used for which a parameter suitable for communication is not necessarily obvious in advance. A network device according to the present invention is provided with a table in which a correlation between identification information about a communication cable and a correction parameter suitable for the communication cable is described, and, when using a communication cable for which identification information is not held, executes a communication test and specifies a correction parameter suitable for the communication cable (shown in Fig. 4).

Description

Network device and communication method

The present invention relates to a technique for performing a communication test on a communication cable connected to a network device.

In recent years, there has been a demand for higher performance for input / output interfaces of electronic computers. In order to improve the performance of the input / output interface, it is necessary to improve the interface speed. Increasing the interface speed means that the signal frequency on the transmission line is increased. As the signal frequency on the transmission line increases, the loss of the signal increases and the influence of the signal reflection noise in the portion where the impedance is mismatched increases, thereby increasing the probability that an error will occur in the signal transmission / reception unit. .

The following Patent Document 1 discloses a technique related to error reduction in an input / output interface. In this document, information about a specific operation mode suitable for operation is stored in the device connected to the input / output interface, and the controller of the input / output interface reads the information to operate the interface suitable for operation. Operate the device in mode. As a result, the probability of an error occurring is reduced.

Special table 2013-500510 gazette

Generally, a general-purpose communication cable does not always store information on a specific operation mode suitable for operation as described in Patent Document 1 described above. Therefore, in a network device (for example, a network switch) in which a general-purpose communication cable is connected to an input / output interface, the controller of the network device reads information about the operation mode from the communication cable and operates the interface in an operation mode suitable for operation. It may be difficult to do.

Also, since general-purpose communication cables have different signal transmission characteristics depending on the type and length of the cable, the manufacturer, etc., the network device needs to operate the interface in an operation mode suitable for each communication cable. However, it is difficult to prepare a suitable interface operation mode in advance for all communication cables that may be connected to the network device.

The present invention has been made in view of the problems as described above, and provides a technique that enables communication in an appropriate operation mode even when a communication cable whose communication parameters are not always clear is used. The purpose is to provide.

The network device according to the present invention includes a table describing a correspondence relationship between identification information of a communication cable and a correction parameter suitable for the communication cable, and uses a communication cable that does not hold the identification information. Perform a test to identify the correct correction parameters for the communication cable.

According to the network device according to the present invention, even when an arbitrary communication cable can be connected to the network device, the interface can be operated in an operation mode suitable for the communication cable.

1 is a block diagram illustrating a configuration of a network device 100 according to a first embodiment. It is a figure which shows the structure and data example of the cable management table 200 which the flash ROM 106 stores. It is a figure which shows the structure and data example of the parameter table 300 which flash ROM106 stores. It is a figure which shows the structure and data example of the parameter table 300 which flash ROM106 stores. It is a figure which shows the structure and data example of the parameter table 300 which flash ROM106 stores. It is a flowchart explaining the process in which the network apparatus 100 determines the necessity of a communication test. It is a flowchart explaining the process of a normal version communication test. It is a flowchart explaining the process of a simplified version communication test. 5 is a flowchart for describing processing in which the network apparatus 100 dynamically adjusts correction parameters of a communication LSI 102.

<Embodiment 1>
FIG. 1 is a block diagram showing a configuration of a network device 100 according to the first embodiment of the present invention. The network device 100 is a device that transmits and receives communication signals via a communication cable 104 connected to the network device 100, and includes a switch LSI (Large Scale Integration) 101, a communication LSI 102, a module connector 103, a CPU (Central Processing Unit) 105, a flash A ROM (Read Only Memory) 106 is provided.

The switch LSI 101 is a circuit that provides a function as a network switch by performing processing for switching communication data. The communication LSI 102 transmits / receives data to / from other communication devices via the communication cable 104. The module connector 103 is a connector for connecting the communication cable 104. The CPU 105 controls the switch LSI 101 and the communication LSI 102. The flash ROM 106 holds correction parameters used when the communication LSI 102 transmits and receives communication signals for each identification information of the communication cable 104.

FIG. 2 is a diagram showing a configuration of the cable management table 200 stored in the flash ROM 106 and an example of data. The cable management table 200 is a data table for managing identification information of the communication cable 104, and holds a module type 201, a cable type 202, a cable length 203, a Vendor model number 204, an optimum setting 205, and a parameter table 206. Since the module type 201, the cable type 202, the cable length 203, and the Vendor model number 204 are parameters that affect the communication characteristics of the communication cable 104, these items can be used as identification information of each communication cable 104. Other items will be described later.

The module type 201 holds the type of the transceiver module to be inserted into the module connector 103. The cable type 202 holds the type of the communication cable 104. The cable length 203 holds the length of the communication cable 104. The Vendor model number 204 is a product model number assigned to each communication cable by the manufacturer of the communication cable 104. The optimum setting 205 and parameter table 206 will be described later.

3A to 3C are diagrams showing a configuration of the parameter table 300 stored in the flash ROM 106 and an example of data. The parameter table 300 is a data table corresponding to the parameter table 206 in FIG. 2, and one parameter table 300 is provided for each record held in the cable management table 200 (that is, for each identification information of the communication cable 104). Here, alphabetical subscripts are added to distinguish each table.

The parameter table 300 is a data table that holds the result of performing a communication test on each communication cable 104. As a result of performing a communication test using each combination of a correction parameter used during transmission and a correction parameter used during reception. The connection availability and error rate (BER: Bit Error Rate) are held for each combination. In the present embodiment, the transmission intensity is exemplified as the transmission correction parameter, and the reception correction amount is exemplified as the reception correction parameter. However, other transmission / reception correction parameters may be used. That is, an appropriate correction parameter that can maintain an appropriate communication waveform at the time of transmission and at the time of reception can be used.

FIG. 4 is a flowchart for explaining processing in which the network device 100 determines whether or not a communication test is necessary. The communication test referred to here is a test performed to specify the correction parameter of the communication LSI 102 suitable for the communication cable 104. Hereinafter, each step of the flowchart shown in FIG. 4 will be described.

(FIG. 4: Step S400)
The CPU 105 starts this flowchart according to a predetermined condition. For example, a case where the user of the network apparatus 100 instructs to start a communication test via an appropriate operation interface, or when the communication LSI 102 detects that the communication cable 104 is connected to the module connector 103 is considered.

(FIG. 4: Step S401)
The CPU 105 reads identification information from the communication cable 104. For example, when the transceiver module used for connecting the communication cable 104 and the module connector 103 has a built-in memory chip, the identification information of the communication cable 104 can be read from the memory chip. The same applies when the module connector 103 itself is configured to be detachable and has a built-in memory chip. The means for reading out the identification information of the communication cable is well-known, for example, by standardization, and will not be described here. If the identification information of the communication cable 104 can be acquired by other appropriate means, that means may be used.

(FIG. 4: Step S402)
The CPU 105 compares the acquired identification information of the communication cable 104 with the identification information in the cable management table 200 stored in the flash ROM 106.

(FIG. 4: Step S403)
If the identification information of the communication cable 104 matches any identification information in the cable management table 200 for the module type 201, the cable type 202, the cable length 203, and the Vendor model number 204, the communication cable 104 Since the optimum correction parameter has already been specified, it is determined that the communication test is unnecessary, and this flowchart is ended. If the identification information of the communication cable 104 does not match any identification information in the cable management table 200, that is, if at least one of the module type 201, the cable type 202, the cable length 203, and the Vendor model number 204 is different. The process proceeds to S404.

(FIG. 4: Steps S404 and S405)
For the module type 201, the cable type 202, and the cable length 203, if the identification information of the communication cable 104 matches any of the identification information in the cable management table 200 and does not match only the Vendor model number 204, the communication The cable 104 is considered to have similar characteristics to the known communication cable 104 already stored in the cable management table 200 except for the Vendor model number 204. Therefore, the CPU 105 performs a simplified version communication test described later with reference to FIG. 6 and specifies a correction parameter suitable for the communication cable 104.

(FIG. 4: Steps S404 and S406)
When the identification information of the communication cable 104 does not match any identification information in the cable management table 200 for all of the module type 201, the cable type 202, and the cable length 203, the communication cable 104 is unknown to the network device 100. It is believed that there is. Therefore, the CPU 105 performs a normal version communication test described later with reference to FIG. 5 and specifies a correction parameter suitable for the communication cable 104.

FIG. 5 is a flowchart for explaining processing of the normal version communication test. Hereinafter, each step of the flowchart shown in FIG. 5 will be described.

(FIG. 5: Step S500)
The CPU 105 starts this flowchart in step S406 of FIG. The communication test can be performed by the network device 100 alone without using an external communication device by connecting both ends of the same communication cable 104 to different module connectors 103. In this case, in order to confirm that the same communication cable 104 is connected, the CPU 105 acquires the identification information of the communication cable 104 via different module connectors 103, and starts the flowchart if the identification information is the same. . When a communication test is performed using an external communication device, the present invention is not limited to this.

(FIG. 5: Steps S501 to S502)
The CPU 105 sets the transmission intensity and the reception correction amount of the communication LSI 102 to minimum values (S501). The CPU 105 controls the switch LSI 101 to perform a communication test by continuing data communication for a specified time in a path passing through the two communication LSIs 102 to which the communication cable 104 is connected (S502). Although the time for continuing the data communication is arbitrary, it is desirable that the communication duration is longer from the viewpoint of improving the accuracy of the error occurrence rate measured by the communication test. In this embodiment, the specified communication duration in the normal version communication test is 20 minutes.

(FIG. 5: Step S503)
The CPU 105 reads from the communication LSI 102 the link state of the communication LSI 102 (whether or not a communication link has been established with the communication destination) and the number of errors that occurred in the communication in step S502, and the link state and error occurrence The rate (which can be calculated from the number of error occurrences) is recorded in the flash ROM 106 as the parameter table 300 regarding the communication cable 104.

(FIG. 5: Step S504)
The CPU 105 determines whether or not a communication test has been performed using all reception correction amount setting values for the transmission intensity set in the communication LSI 102 at that time. When there is a reception correction amount setting value that has not been tested, the process proceeds to step S505, and when the communication test is completed for all reception correction amount setting values, the process proceeds to step S506.

(FIG. 5: Step S505)
The CPU 105 increases the reception correction amount setting value of the communication LSI by one level, returns to step S502, and performs a communication test again. Specific numerical values for each level of the reception correction amount setting value may be determined in advance for each type of the assumed communication cable 104, for example, or the same value may be used uniformly. The same applies to the level of transmission intensity described later.

(FIG. 5: Step S506)
The CPU 105 sets the reception correction amount of the communication LSI 102 to the minimum value.

(FIG. 5: Step S507)
The CPU 105 determines whether or not a communication test has been performed using all transmission strengths that can be set in the communication LSI 102. If transmission strength that has not been tested remains, the process proceeds to step S508, and if communication tests have been completed for all transmission strengths, the process proceeds to step S509. In this flowchart, since the transmission strength is gradually increased, when the transmission strength reaches the maximum value that can be set in the communication LSI 102, it can be considered that the communication test has been completed for all the transmission strengths.

(FIG. 5: Step S508)
The CPU 105 increases the transmission intensity of the communication LSI 102 by one level, returns to step S502, and performs a communication test again.

(FIG. 5: Step S509)
The CPU 105 determines an optimal correction parameter of the communication LSI 102 for the communication cable 104 from the parameter table 300 created during the communication test. The CPU 105 adds the identification information of the communication cable 104 and the determined optimum correction parameter of the communication LSI 102 to the cable management table 200 in association with the parameter table 300 created in the course of the communication test. The optimum correction parameter can be designated as the optimum setting 205. The association with the parameter table 300 can be specified by storing the name of the table as the parameter table 206, for example.

(FIG. 5: Step S509: Supplement)
A method for determining the optimum correction parameter of the communication LSI 102 will be described with reference to FIG. 3B. In the normal version communication test up to step S509, for example, it is assumed that a parameter table 300b shown in FIG. 3B is obtained. For example, the CPU 105 obtains an average value of error occurrence rates for all nine combinations including a combination before and after a certain combination of transmission intensity and reception correction amount in the parameter table 300. The combination of the transmission intensity and the reception correction amount, which is the center of the nine combinations with the lowest error occurrence rate, is considered to be a correction parameter that can be stably communicated. Can be determined. The method for determining the optimum correction parameter is not necessarily limited to this, and any method can be used.

FIG. 6 is a flowchart for explaining processing of the simplified version communication test. Hereinafter, each step of the flowchart shown in FIG. 6 will be described.

(FIG. 6: Step S601)
The CPU 105 reads the identification information in which the module type 201, the cable type 202, and the cable length 203 match the communication cable 104 from the cable management table 200, and acquires the optimum setting 205. The CPU 105 sets the correction parameter specified by the acquired optimum setting 205 in the communication LSI 102. This step is for diverting the optimal correction parameter of a known communication cable similar to the communication cable 104 to be tested.

(FIG. 6: Steps S602 to S603)
The CPU 105 confirms the link state of the communication LSI 102. If it is not possible to link normally, the characteristics of the communication cable 104 to be tested are considered to be significantly different from those of the known communication cable. Therefore, the simplified communication test is stopped, and the process proceeds to step S603, where the normal communication cable described in FIG. Conduct a version communication test. If the link is established, the process proceeds to step S604.

(FIG. 6: Steps S604 to S605)
The CPU 105 performs data communication via the communication cable 104 to be tested by the same method as step S502 in FIG. 5 (S604). The CPU 105 records the link state and error occurrence rate of the communication LSI 102 in the flash ROM 106 by the same method as in step S503 in FIG. 5 (S605).

(FIG. 6: Step S606)
The CPU 105 determines whether or not the error occurrence rate of the test target communication cable 104 recorded in step S605 exceeds the error occurrence rate of the known similar communication cable specified in step S601. If it exceeds, it is determined that the transmission characteristic of the communication cable 104 to be tested is different from that of a known similar cable, and the process proceeds to step S603 to perform the normal version communication test described with reference to FIG. If the error occurrence rate is equal to or lower than the known similar communication cable, the process proceeds to step S607.

(FIG. 6: Step S606: Supplement 1)
Before proceeding from step S602 or step S606 to step S603, a correction parameter close to the optimal setting 205 of the known communication cable identified in step S601 may be set in the communication LSI 102, and steps S604 to S606 may be performed again. As correction parameters close to the optimum setting 205, for example, eight combinations around the optimum setting 205 in the parameter table 300 can be used.

(FIG. 6: Step S606: Supplement 2)
In this step, even if the error occurrence rate of the communication cable 104 to be tested exceeds the error occurrence rate of the known similar communication cable, if the excess amount is small, the process proceeds to step S607 and the known correction parameter is set. You may divert. That is, if the error occurrence rate of the communication cable 104 to be tested is within a predetermined range compared to the error occurrence rate of the known cable, it may be considered that the known correction parameter can be used.

(FIG. 6: Step S607)
The CPU 105 associates the combination of the identification information of the communication cable 104 and the optimal setting 205 of the known communication cable specified in step S601 with the parameter table 300 created in the course of the communication test, and then stores it in the cable management table 200. to add. The correspondence between the items is the same as that in step S509 in FIG.

<Embodiment 1: Summary>
As described above, when the identification information of the communication cable 104 is not stored in the cable management table 200, the network device 100 according to the first embodiment performs the communication test and communicates with the communication cable 104. Is determined, and the correction parameter is added to the cable management table 200. Thereby, even if it is a case where the unknown communication cable 104 is used, it can communicate using an optimal interface operation mode.

The network device 100 according to the first embodiment also includes known identification information in the cable management table 200 in which the module type 201, the cable type 202, and the cable length 203 are the same among the identification information of the communication cable 104 and the others are different. In the case where it is recorded, the simplified version communication test is performed by diverting the correction parameter corresponding to the known identification information. Thereby, the communication test with respect to the unknown communication cable 104 can be simplified.

In the first embodiment, it has been described that the simplified communication test is performed when only the Vendor model number 204 of the identification information of the communication cable 104 is different. This is because it is considered that the communication characteristics are similar if the module type 201, the cable type 202, and the cable length 203 are the same. Therefore, as long as at least the module type 201, the cable type 202, and the cable length 203 are the same, the simplified communication test may be performed in the same manner. That is, if these items are the same, the same flow as in FIG. 4 can be performed even when identification information other than the Vendor model number 204 is used.

<Embodiment 2>
In the first embodiment, it has been described that the normal version communication test or the simplified version communication test is performed based on whether or not the identification information of the communication cable 104 is known. Even after the correction parameters are specified by these communication tests or after communication is started using the known communication cable 104, the optimal correction parameters may change due to factors such as environmental changes. Therefore, in the second embodiment of the present invention, a configuration example in which the correction parameter is dynamically adjusted will be described. Since the configuration of the network device 100 is the same as that of the first embodiment, the following description focuses on processing for dynamically adjusting correction parameters.

FIG. 7 is a flowchart for explaining processing in which the network device 100 dynamically adjusts the correction parameters of the communication LSI 102. Hereinafter, each step of the flowchart shown in FIG. 7 will be described.

(FIG. 7: Step S700)
For example, the CPU 105 starts this flowchart when the communication LSI 102 detects the occurrence of an error exceeding a specified value. Alternatively, the network device 100 may be started by giving an instruction via an appropriate operation interface.

(FIG. 7: Step S701)
The CPU 105 refers to the parameter table 300 corresponding to the identification information of the communication cable 104 connected to the communication LSI 102, and acquires a value that is one step larger than the current optimum setting value for the transmission intensity of the communication LSI 102. The CPU 105 attempts communication using the transmission intensity. If a communication link can be established with the transmission destination, the process proceeds to step S702, and if not, the process skips to step S703.

(FIG. 7: Step S702)
The CPU 105 temporarily changes the transmission intensity of the communication LSI 102 from the current optimum setting value to a value larger by one step, and continues communication for a specified time and records the error occurrence rate.

(FIG. 7: Step S703)
The CPU 105 refers to the parameter table 300 corresponding to the identification information of the communication cable 104 connected to the communication LSI 102, and acquires a value that is one step smaller than the current optimum setting value for the transmission intensity of the communication LSI 102. The CPU 105 attempts communication using the transmission intensity. If a communication link can be established with the transmission destination, the process proceeds to step S704, and if not, the process skips to step S705.

(FIG. 7: Step S704)
The CPU 105 temporarily changes the transmission intensity of the communication LSI 102 from the current optimum setting value to a value that is one step smaller, and continues communication for a specified time and records the error rate.

(FIG. 7: Step S705)
The CPU 105 refers to the parameter table 300 corresponding to the identification information of the communication cable 104 connected to the communication LSI 102, and acquires a value that is one step larger than the current optimum setting value for the reception correction amount of the communication LSI 102. The CPU 105 attempts communication using the reception correction amount. If a communication link can be established with the transmission destination, the process proceeds to step S706, and if not, the process skips to step S707.

(FIG. 7: Step S706)
The CPU 105 temporarily changes the reception correction amount of the communication LSI 102 from the current optimum setting value to a value that is one step larger, and continues communication for a specified time and records the error occurrence rate.

(FIG. 7: Step S707)
The CPU 105 refers to the parameter table 300 corresponding to the identification information of the communication cable 104 connected to the communication LSI 102, and acquires a value that is one step smaller than the current optimum setting value for the reception correction amount of the communication LSI 102. The CPU 105 attempts communication using the reception correction amount. If a communication link can be established with the transmission destination, the process proceeds to step S708, and if not, the process skips to step S709.

(FIG. 7: Step S708)
The CPU 105 temporarily changes the reception correction amount of the communication LSI 102 from the current optimum setting value to a value one step smaller, and continues communication for a specified time and records the error occurrence rate.

(FIG. 7: Steps S709 to S710)
The CPU 105 determines a correction parameter having the lowest error occurrence rate as a new optimum value from the error occurrence rates measured in Step S702, Step S704, Step S706, and Step S708 (S709). The CPU 105 stores the new optimum setting 205 in the cable management table 200, reflects the measured error occurrence rate in the parameter table 300, and applies the new optimum setting 205 to the communication LSI 102.

<Embodiment 2: Summary>
As described above, when the error occurrence rate reaches the specified value, the network device 100 according to the second embodiment attempts communication using the other correction parameters described in the parameter table 300, and the optimal correction parameter is set. Is identified again. Thereby, even when the optimal correction parameter changes, it can be dynamically readjusted.

In the second embodiment, the example in which the transmission intensity and the reception correction amount are each ± 1 from the optimum setting value has been described. However, the example of the correction parameter that is temporarily used is not limited to this, and is described in the parameter table 300. The communication test may be performed again using at least a part of the correction parameters.

100: network device, 101: switch LSI, 102: communication LSI, 103: module connector, 104: communication cable, 105: CPU, 106: flash ROM.

Claims

Connector to connect communication cable,
A communication circuit for transmitting and receiving communication signals via a communication cable connected to the connector;
An arithmetic unit that transmits and receives communication signals using the communication circuit,
A storage unit for storing a parameter table describing a correspondence relationship between identification information of one or more communication cables and a correction parameter to be used in communication using the communication cable identified by the identification information;
With
The calculation unit obtains identification information of a communication cable connected to the connector,
The computing unit is
When the identification information acquired by the arithmetic unit matches any identification information described in the parameter table, the communication circuit transmits and receives a communication signal using the correction parameter corresponding to the identification information. ,
When the identification information acquired by the arithmetic unit does not match any identification information described in the parameter table, a communication signal is transmitted using a communication cable connected to the connector by performing a communication test. A network device, wherein a correction parameter capable of transmitting and receiving is specified, and a combination of the specified correction parameter and identification information acquired by the calculation unit is added to the parameter table.
The computing unit is
Among the items included in the identification information acquired by the calculation unit, the type of transceiver module connected to the connector, the type of communication cable used by the communication circuit, and the length of the communication cable are described in the parameter table. The at least one of the other items of the identification information does not match, the correction parameter corresponding to the first identification information is acquired,
A normal version communication test performed when the identification information acquired by the calculation unit does not match any of the identification information described in the parameter table by diverting the acquired correction parameter to the communication cable. The network apparatus according to claim 1, wherein a simplified version of the communication test is performed.
The computing unit is
If the error rate when the simplified communication test is performed is less than or equal to a predetermined allowable value, the combination of the correction parameter used at that time and the identification information acquired by the calculation unit is added to the parameter table. The network device according to claim 2, wherein:
The computing unit is
If the error rate when the simplified version communication test is performed exceeds the allowable value, a correction parameter that can transmit and receive communication signals is identified by performing the normal version communication test, and the identification is performed. The network device according to claim 3, wherein the corrected parameter is added to the parameter table.
The computing unit is
When a communication link could not be established by performing the simplified version communication test, a correction parameter capable of transmitting and receiving a communication signal was identified by performing the normal version communication test, and the identified The network device according to claim 2, wherein a correction parameter is added to the parameter table.
The computing unit is
When a communication link could not be established by performing the simplified communication test, using the correction parameters described in the parameter table other than those corresponding to the first identification information, The network device according to claim 2, wherein the simplified communication test is performed again.
The network device includes a plurality of the connectors,
When the communication cable is connected to the plurality of connectors, the arithmetic unit acquires the identification information of the communication cable from the communication cable connected to each of the connectors,
When the identification information acquired from the communication cables connected to the two connectors is the same, the calculation unit checks whether the identification information exists in the parameter table. The network device according to claim 1, wherein a communication test is performed.
The parameter table is
A plurality of parameter sets in which at least one of a correction parameter to be used when transmitting the communication signal and a correction parameter to be used when receiving the communication signal are changed are described as the correction parameter,
The computing unit is
A communication test is performed using each of the plurality of parameter sets described in the parameter table, the parameter set that is connectable and has the lowest error rate is identified, and the identified parameter set is used. A flag indicating that a communication signal should be transmitted and received is recorded in the parameter table,
The network device according to claim 1, wherein the communication circuit transmits and receives a communication signal using the parameter set corresponding to the flag.
The parameter table is
A plurality of parameter sets in which at least one of the transmission intensity of the communication signal and the reception correction amount of the communication signal is changed are described as the correction parameter,
The computing unit is
After starting transmission / reception of communication signals by the communication circuit, a communication test is performed using a part of the plurality of parameter sets described in the parameter table to obtain a connectable and lowest error rate. The specified parameter set is specified, and a flag indicating that a communication signal should be transmitted and received using the specified parameter set is recorded in the parameter table,
The network device according to claim 1, wherein the communication circuit transmits and receives a communication signal using the parameter set corresponding to the flag.
A method for transmitting and receiving communication signals using a network device having a connector for connecting a communication cable,
From the storage unit that stores a parameter table describing a correspondence relationship between identification information of one or more communication cables and a correction parameter to be used when communication is performed using the communication cable identified by the identification information. Reading the table,
Obtaining identification information of a communication cable connected to the connector;
If the acquired identification information matches any identification information described in the parameter table, transmitting and receiving a communication signal using the correction parameter corresponding to the identification information;
If the acquired identification information does not match any identification information described in the parameter table, a communication signal is transmitted and received using a communication cable connected to the connector by performing a communication test. Specifying a correction parameter that can be added, and adding the combination of the specified correction parameter and the acquired identification information in the parameter table;
A communication method characterized by comprising: