WO2016080065A1

WO2016080065A1 - Communication device, wrong connection determination method and program

Info

Publication number: WO2016080065A1
Application number: PCT/JP2015/076449
Authority: WO
Inventors: 廣明片岡
Original assignee: 日本電気株式会社
Priority date: 2014-11-17
Filing date: 2015-09-17
Publication date: 2016-05-26

Abstract

This communication device (10a) comprises: a plurality of ports (24-1a, 24-2a) to which cables for communicating with a partner device (10b) are connected; a light-emitting unit (23-1a) for notifying an operator of whether or not there is a wrong connection in the cables; a communication processing unit (21-1a) which, when a cable is connected to at least one port among the plurality of ports, transmits/receives a communication frame for determining whether or not connection at a data link layer level is good to/from the partner device (10b) via the cable at regular intervals; and a connectivity verification unit (22a) which, with reference to a preregistered set value and the communication frame received from the partner device, determines whether or not there is a wrong connection with the partner device (10b) at the data link layer level, and when determining that there is a wrong connection, turns on the light-emitting unit (23-1a).

Description

Communication device, erroneous connection determination method, and program

The present invention relates to a communication device connected to another device via a network cable, an erroneous connection determination method, and a program for causing a computer to execute the method.

Along with the expansion of the scale of the communication network, the number of communication devices connected to the communication network has become enormous, and the connection state between the communication devices is automatically maintained and managed (Non-Patent Documents 1 and 2). reference).

In Non-Patent Document 1, a function called Ethernet (registered trademark) OAM (Operations, Administration and Maintenance) is defined for the purpose of maintenance and management of communication devices. In order to confirm communication at the layer 2 (data link layer) level, Ethernet (registered trademark) OAM has three functions, one of which is an ETH-CC (Continuity Check) function related to connection inspection. In the ETH-CC function, CCM (Continuity Check) frames are periodically transmitted and received between communication devices, so that these communication devices can confirm the communication state with each other.

FIG. 1A and FIG. 1B are diagrams showing a frame configuration defined in Non-Patent Document 1. FIG. 1A shows the format of CCM PDU (Protocol Data） Unit), and FIG. 1B shows the format of Flags shown in FIG. 1A.

As shown in FIG. 1A, the CCM frame includes an MEG ID for identifying a MEG (Maintenance Entity Group), a MEP ID for identifying a MEP (Maintenance group End Point), It includes MEL (MEG Level) indicating the management level of the group targeted by the frame, and Flags information. As shown in FIG. 1B, Flags includes Period, which is information indicating the transmission period of the own frame. Examples of techniques using CCM frames are disclosed in

Patent Documents

1 and 2.

Non-Patent Document 2 defines LLDP (Link Layer Discovery Protocol) for the purpose of managing communication devices and terminals connected to a communication network. LLDP is a layer 2 level protocol for notifying neighboring devices of information such as the type of device and setting values between devices. The format of the LLDP frame transmitted / received between devices is shown in FIG.

Patent Document 3 discloses an example of a method for detecting an erroneous connection at a layer 2 level using a MAC (Media Access Control) address learning function. Further, in Patent Document 4, when an operator connects a cable to a router device, if the cable is connected to an incorrect port, the setting contents in the own device can be changed so that the router device becomes a normal connection. It is disclosed.

JP 2013-005123 A JP 2012-182760 A JP 2008-124791 A JP 2008-092255 A

When performing network construction such as cable replacement or new installation, the operator needs to check whether the communication device is normally connected via the communication network. In the situation where the configuration (setting) of each communication device is properly implemented, an operator may mistakenly connect a cable during network construction. In this case, an operator cannot check the cable connection state unless an information processing terminal for monitoring is connected to a host system such as an NMS (Network Management System) that manages communication devices of a communication network. There was a problem that it took a long time to check the connection. Even if the operator connects the information processing terminal to the host system and overlooks the wrong cable connection, the host system must be checked to make sure that the communication device settings are correct in order to make the cable connection normal. Needs to be reviewed. As a result, the progress of network construction is further delayed.

Note that, in any case of the methods disclosed in Patent Documents 1 to 3, the worker needs to connect the information processing terminal to the host system as described above. Further, in the method disclosed in Patent Document 4, not only the configuration of the router device is complicated, but also the setting replacement processing in the router device becomes heavy when the setting contents are complicated.

One of the objects of the present invention is to provide a communication device, an erroneous connection determination method, and a program that make it easy to visually recognize whether there is an erroneous connection at the L2 level.

A communication device according to one aspect of the present invention includes a plurality of ports to which a cable for communicating with an opposite device is connected, a light emitting unit for notifying an operator whether or not there is a misconnection of the cable, and a plurality of ports When a cable is connected to at least one of the ports, a communication processing unit that transmits and receives a communication frame for determining whether or not the connection is good at the data link layer level with the opposite device via the cable at a certain period; Referring to the pre-registered setting value and the communication frame received from the opposite device, it is determined whether there is an erroneous connection with the opposite device at the data link layer level. And a connectivity verification unit to be lit.

An erroneous connection determination method according to an aspect of the present invention includes a plurality of ports to which a cable for communicating with an opposite device is connected, and a light emitting unit for notifying an operator of whether there is an erroneous connection of the cable. An erroneous connection determination method by a communication device having a communication frame for determining whether or not a connection is good at a data link layer level at a fixed period when a cable is connected to at least one of a plurality of ports. Determine whether there is a misconnection at the data link layer level with the opposite device by transmitting / receiving via the cable with the opposite device, referring to the pre-registered setting value and the communication frame received from the opposite device, and determining As a result, if it is determined that there is an erroneous connection, the light emitting unit is turned on.

A program according to one aspect of the present invention provides a computer having a plurality of ports to which a cable for communicating with an opposite device is connected, and a light emitting unit for notifying an operator of whether or not there is a misconnection of the cable. , When a cable is connected to at least one of the plurality of ports, a procedure for transmitting / receiving a communication frame for determining whether or not the connection is good at the data link layer level with the opposite device via the cable at a certain period; , A procedure for determining whether or not there is an erroneous connection at the data link layer level with the opposite device with reference to a pre-registered set value and a communication frame received from the opposite device, and as a result of the determination, there is an erroneous connection If it is determined, the procedure for turning on the light emitting unit is executed.

FIG. 1A is a diagram illustrating a configuration of a frame defined in Non-Patent Document 1. FIG. 1B is a diagram showing a configuration of a part of the frame shown in FIG. 1A. FIG. 2 is a diagram illustrating a frame configuration defined in Non-Patent Document 2. FIG. 3 is a block diagram showing a configuration example of the communication apparatus according to the present embodiment. FIG. 4 is a flowchart showing an operation procedure by the communication apparatus of the present embodiment. FIG. 5 is a diagram for explaining Example 1 of the erroneous connection determination method of the present embodiment. FIG. 6 is a diagram for explaining Example 2 of the erroneous connection determination method of the present embodiment. FIG. 7 is a block diagram showing another configuration example of the communication apparatus of this embodiment.

The configuration of the communication apparatus of this embodiment will be described. The communication device is a network communication device including a switching hub and a router, for example.

FIG. 3 is a block diagram illustrating a configuration example of the communication apparatus according to the present embodiment.

FIG. 3 shows a configuration in which the communication device 10a and the communication device 10b of this embodiment are connected by a cable. The communication device 10a is connected to the host system 51, and the communication device 10b is connected to the host system 52. The

host systems

51 and 52 are, for example, NMS (Network Management System). In this embodiment, network construction is performed between the communication device 10a and the communication device 10b, and it is determined whether or not the cable between these communication devices is correctly connected.

FIG. 3 shows a configuration in which the communication device 10a and the communication device 10b are connected by peer-to-peer, but a relay device may be connected between these communication devices. Here, with reference to FIG. 3, a case will be described where no relay device is connected between the communication device 10 a and the communication device 10 b. Further, ETH-CC defined in Non-Patent Document 1 is used for correct / incorrect determination of cable connection.

FIG. 3 shows a case where two pairs of twisted pair cables are connected between the communication device 10a and the communication device 10b. However, the number of twisted pair cables is not limited to two. Since the communication device 10a and the communication device 10b have the same configuration, the configuration of the communication device 10a will be described in detail below, and the description of the communication device 10b will be omitted.

As shown in FIG. 3, the communication device 10a includes an OAM processing unit 21-1a to 21-2a, a connectivity verification unit 22a, ports 24-1a to 24-2a, and an LED (Light Emitting Diode) 23-1a. 23-2a.

The OAM processing units 21-1a to 21-2a function as communication processing units that transmit and receive ETH-CC to the communication device 10b. The OAM processing units 21-1a to 21-2a analyze the ETH-CC received from the communication device 10b, read line information including the MEG ID and MEP ID from the ETH-CC, and notify the connectivity verification unit 22a. Further, the OAM processing units 21-1a to 21-2a generate ETH-CC according to the setting value of the communication device 10a, and send the ETC-CC to the communication device 10b via the ports 24-1a to 24-2a and the cable. Send. The line information includes MEL, MEG ID, MEP ID, and Period.

The connectivity verification unit 22a has a memory (not shown) in which the setting value of the communication device 10a is registered in advance. The set value includes values of parameters such as MEL, MEG ID, and MEP ID in the format shown in FIG. 6 corresponding to each port. The set value includes not only the own device but also the parameters of the opposite device. For example, corresponding to each port of the communication device 10a, the MEP ID of the port connected to the communication device 10b side is registered in the setting value on the communication device 10a side. Hereinafter, the parameter on the opposite device side registered in the setting value of the own device is referred to as “expected value”.

The connectivity verification unit 22a determines whether or not an ETH-CC failure has occurred by referring to the line information notified from the OAM processing units 21-1a to 21-2a and the setting value registered in advance. To do. When the connectivity verification unit 22a detects an ETH-CC failure, the connectivity verification unit 22a identifies the correct connection destination from the setting value of the communication device 10a, and instructs the LED corresponding to the identified port to turn on. When the connectivity verification unit 22a recognizes that the ETH-CC failure has been resolved from the line information notified from the OAM processing units 21-1a to 21-2a, it instructs the LED that has been instructed to turn off. In addition, the connectivity verification unit 22a notifies the upper system 51 of the normality of the connection based on the notified line information. The configuration of the connectivity verification unit 22a is preferably a dedicated circuit including an ASIC (Application Specific Specific Integrated Circuit). However, a CPU (Central Processing Unit) that executes processing according to a program is provided, and the CPU has the above functions. May be executed.

The LEDs 23-1a to 23-2a are provided corresponding to the ports 24-1a to 24-2a of the communication device 10a. Although FIG. 3 shows a case where the number of ports is two for ease of explanation, as described above, three or more ports may be provided.

The LEDs 23-1a to 23-2a are turned on or off according to an instruction from the connectivity verification unit 22a. In the present embodiment, a case will be described in which the LEDs 23-1a to 23-2a are provided separately from link LEDs (not shown) for displaying the correctness of physical connection. It is desirable that the LEDs 23-1a to 23-2a be arranged at positions that are easy for the operator to see. For example, if the LEDs 23-1a to 23-2a are arranged on the front side of the communication device, the operator recognizes whether or not there is an incorrect connection of the cable and the position of the correct connection destination port when there is an incorrect connection. There is an advantage that it becomes easy to do.

In addition, since the LED that is lit serves to guide the worker to the correct connection destination of the cable, this LED is hereinafter referred to as a guidance LED.

When the communication device 10a is used as a reference, the communication device 10b corresponds to the opposite device of the communication device 10a. When the communication device 10b is used as a reference, the communication device 10a corresponds to the opposite device of the communication device 10b.

Further, although the case where the OAM processing unit reads the line information from the communication frame and notifies the connectivity verification unit has been described, the OAM processing unit transfers the received communication frame to the connectivity verification unit, and the connectivity verification unit performs communication. The line information may be read from the frame.

Further, although the case has been described in which the line information referred to by the connectivity verification unit for determination of erroneous connection is MEL, MEG ID, MEP ID, and Period, it is not limited to these parameters. Further, a memory (not shown) may be provided in the OAM processing unit, and the setting value of the own device may be stored in the memory in advance, and instead of providing the memory in the OAM processing unit, the OAM processing unit is connected to the connectivity verification unit. The set value may be read out.

Next, the operation procedure of the erroneous connection determination method by the communication device 10a described with reference to FIG. 3 will be described. FIG. 4 is a flowchart showing an operation procedure by the communication apparatus of the present embodiment. FIG. 5 is a diagram showing a specific example of the erroneous connection determination method of the present embodiment.

As shown in FIG. 4, after the network construction is performed from the normal state before the network construction, the communication device 10a transmits / receives the CCM shown in FIG. 6 to the communication device 10b at a constant cycle. When the communication device 10a receives the CCM from the communication device 10b (step 1001), the communication device 10a determines whether the values of the four parameters MEL, MEG ID, MEP ID, and Period described in the CCM match the expected value of the own device. To check the normality of the connection.

If any one of the above four parameters does not match as a result of the determination, the communication device 10a determines that an ETH-CC failure has occurred (step 1002), and the above 4 included in the received CCM. Ports with the same value of the two parameters are searched with the set value (step 1003). As a result of the search, if there is another port having the same value of the four parameters as a result of the search, the communication device 10a identifies the port to be connected. The communication device 10a turns on the LED corresponding to the identified port as the guidance LED (step 1004).

Thereafter, when the cable is connected to the correct port by the operator, the communication device 10a determines that the ETH-CC failure has been canceled as a result of the determination in step 1002 (step 1005), and turns off the guidance LED (step 1006). ).

Hereinafter, a specific example of the erroneous connection determination method of the present embodiment will be described. The first embodiment is a case where the communication device 10a and the communication device 10b are connected by peer-to-peer. The second embodiment is a case where a relay device is connected between the communication device 10a and the communication device 10b.

An example of the erroneous connection determination method of the present embodiment will be described with reference to FIG.

FIG. 5 shows a case where the port 24-1a of the communication device 10a is to be connected to the port 24-2b of the communication device 10b via a cable, but the port 24-1a and the port 24-1b are erroneously connected. .

As shown in FIG. 5, the communication device 10a sends a CCM including line information of “MEL: 5, MEG ID: GRP1, MEP ID: 210 and Period: 3.3ms” via the port 24-1a. Send to.

When the communication device 10b receives the CCM from the communication device 10a via the port 24-1b, the communication device 10b reads the values of the parameters of MEL, MEG 、 ID, MEP ID, and Period from the received CCM. Then, the connectivity verification unit 22b of the communication device 10b detects an ETH-CC failure because the MEPＣＭID of the received CCM is different from the expected MEP ID set in the port 24-1b. Subsequently, the connectivity verification unit 22b estimates that the port to receive the CCM received via the port 24-1b from the set value of the port 24-2b is the port 24-2b, and corresponds to the port 24-2b. The LED 23-2b to be turned on is turned on as an induction LED.

Another example of the erroneous connection determination method of this embodiment will be described with reference to FIG.

FIG. 6 shows a configuration example when the relay device 30 is connected between the communication device 10a and the communication device 10b. The communication device 10b shown in FIG. 6 has ports 24-1b to 24-3b, and LEDs 23-1b to 23-3b corresponding to these ports. However, in FIG. 6, a part of the configuration shown in FIG. 3 including the LEDs 23-1b to 23-2b is not shown in the drawing. In FIG. 6, a thick solid line connecting the

connectivity verification units

22a and 22b schematically represents whether or not the connection is normal.

FIG. 6 shows a case where the port 24-2a of the communication device 10a should be connected to the port 24-3b of the communication device 10b, but the port 24-2a is erroneously connected to the port 24-2b. In order to simplify the description, a description will be given of a case where the

communication devices

10a and 10b determine whether or not the connection is correct using the MEP ID.

The communication device 10a transmits a CCM including information of MEP ID: 200 to the communication device 10b via the port 24-1a, and transmits a CCM including information of MEPＭID: 400 to the communication device 10b via the port 24-2a. Send. When the relay device 30 receives the CCM from the communication device 10a, the relay device 30 refers to the MEP ID of the CCM to identify the destination communication device 10b and transfers the CCM to the communication device 10b.

When the communication device 10b receives the CCM from the communication device 10a via the port 24-1b, the communication device 10b reads the MEP ID from the received CCM. Then, the connectivity verification unit 22b of the communication device 10b determines that the connection is normal when the MEPＣＭID of the received CCM matches the expected MEP ID set in the port 24-1b.

Further, when the communication device 10b receives the CCM from the communication device 10a via the port 24-2b, the communication device 10b reads the MEP ID from the received CCM. Then, the connectivity verification unit 22b detects an ETH-CC failure because the MEPＣＭID of the received CCM is different from the expected MEP ID set in the port 24-2b. In this case, the connectivity verification unit 22b refers to the setting value of the port 24-3b to estimate that the port that should receive the CCM received via the port 24-2b is the port 24-3b. The LED 23-3b corresponding to 24-3b is turned on as an induction LED.

In the communication apparatus of this embodiment, by using the ETH-CC function of Ethernet (registered trademark) OAM, an erroneous cable connection is detected at the time of network construction, and there is an erroneous cable connection at the L2 level. The operator can be notified quickly by lighting. The operator does not need to check the network state by connecting the information processing terminal to the host system, and can quickly recognize erroneous connection of the cable at the L2 level.

Also, if there is a cable misconnection, the communication device can identify the port to be connected based on the ETH-CC line information received from the opposite device. Therefore, the communication device can indicate the correct port of the cable connection destination to the operator by turning on the guidance LED of the specified port. The induction LED can reduce the time required to reconnect the cable from the wrong connection state to the correct port.

Here, a modification of this embodiment will be described.

In the modified example, LLDP defined in Non-Patent Document 2 is used instead of ETH-CC.

The configuration of the communication device in this modification will be described with reference to FIG. A detailed description of the same configuration as that described with reference to FIG. 3 is omitted. In the modification, the OAM processing unit illustrated in FIG. 3 is referred to as a communication processing unit.

In the setting information registered in the connectivity verification unit 22a of the communication device 10a, the expected value of Port ID TLV of the frame shown in FIG. 2 corresponding to each port is set in advance. Port ID TLV is an identifier for specifying a transmission source port of the LLDP frame. That is, the port identifier corresponding to the port of the communication device 10a is set as an expected value from which port of the communication device 10b the LLDP frame is transmitted.

Next, the operation procedure by the communication device according to the modification will be briefly described. Here, the case where the communication device 10a is the main subject of operation and the communication device 10b is the opposite device of the communication device 10a is described.

When the worker connects the communication device 10a and the communication device 10b with a cable, the communication processing unit of the communication device 10a detects the communication device 10b as an adjacent node and transmits / receives an LLDP frame to / from the communication device 10b. Subsequently, the connectivity verification unit 22a compares the Port ID TLV of the LLDP frame received from the communication device 10b with a preset expected value, and determines whether the Port フレーム ID TLV of the frame matches the expected value. judge. If the connectivity verification unit 22a determines that the transmission source of the frame does not match the expected value, the connectivity verification unit 22a searches the expected value that matches the received PortＰID TLV with the expected value set for each port, and guides the matching port. The LED is turned on as a port.

This modification is not limited to the case where the communication device 10a and the communication device 10b are connected by peer-to-peer, and a relay device may be connected between these communication devices. When a relay device is provided between the communication devices, the relay device may read the identifier of the destination device with reference to the LLDP frame and transfer the LLDP frame to the device specified by the identifier.

In the above-described embodiment, the case where the ETH-CC or LLDP frame is used has been described. However, the line information is transmitted using the original frame format, the OAM extension, and the LLDP extension without using these frames. You may exchange between.

In addition, when ETH-CC failures are detected simultaneously on multiple ports, a common policy is determined in advance between the own device and the opposite device, such as selecting the port with the smallest MEP ID, and the communication device follows the common policy. One representative port may be selected and the corresponding LED may be turned on as a guide LED.

Also, it is possible to prevent the occurrence of ETH-CC failure in advance. An example of the method will be described. Assume that an operator connects at least one cable between communication devices, and there are a plurality of ports that are port-enabled and not connected to a cable when no ETH-CC failure is detected. At this time, the connectivity verification unit of one communication device selects one port to which the next cable is connected from the plurality of ports, and transmits the line information of the selected port to the opposite device via the connected cable. In addition to transmitting, the LED of the selected port is turned on. The opposite device turns on the LED of the port corresponding to the received line information as a guide LED. In this way, it is possible to guide the correct cable connection to the operator by lighting the guidance LEDs of the own device and the opposite device in pairs.

Further, in the above-described embodiment, the case where the LEDs corresponding to the number of ports are provided on the front surface of the communication apparatus has been described. However, one LED may be provided for notifying the operator of the presence or absence of erroneous connection. . FIG. 7 is a block diagram showing another configuration example of the communication apparatus of this embodiment. When the connectivity verification detects an erroneous connection at the data link layer level, the LED 25 shown in FIG. 7 is turned on. According to this configuration, the operator can not only quickly recognize the presence or absence of cable misconnection, but also can reduce the manufacturing cost of the communication device.

Further, instead of providing an LED that functions as an induction LED, an existing link LED (not shown) may be operated as the induction LED. For example, when there is a problem with the physical connection, the link LED blinks, but when the link LED blinks as an inductive LED, the connectivity verification unit of the communication device has a blinking cycle when there is a problem with the physical connection. To be different. Further, the emission color may be different between when there is a problem in physical connection and when there is an erroneous connection at the data link layer level. For example, when there is a problem with the physical connection, the connectivity verification unit of the communication apparatus blinks the link LED in green, and when there is an erroneous connection at the data link layer level, blinks the link LED in orange.

Furthermore, the device that executes the erroneous connection determination method of the present embodiment is not limited to a communication device, and may be a computer having a memory that stores a program and a CPU that executes processing according to the program. By storing a program describing the procedure of the above-described erroneous connection determination method in a computer memory, the method of the present invention can be executed by the computer.

A program describing the procedure of the erroneous connection determination method described above may be stored in a computer-readable recording medium. In this case, it is possible to cause the other information processing apparatus to execute the above-described erroneous connection determination method by installing the program from the recording medium to the other information processing apparatus.

As an example of the effect of the present invention, when the communication devices are connected with a cable, if the cable is erroneously connected at the L2 level, the operator can immediately recognize that there is an erroneous connection.

The present invention has been described above with reference to the embodiments, but the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

Note that this application incorporates all the contents of Japanese Patent Application No. 2014-232362 filed on November 17, 2014, and claims priority based on this Japanese application.

10a, 10b Communication devices 21-1a to 21-2a, 21-1b to 21-2b

OAM processing units

22a and 22b Connectivity verification units 23-1a to 23-2a, 23-1b to 23-2b LED
24-1a to 24-2a, 24-1b to 24-2b ports

Claims

A plurality of ports to which cables for communicating with the opposite device are connected;
A light emitting unit for notifying the operator of whether there is a cable misconnection,
When a cable is connected to at least one of the plurality of ports, a communication frame for determining whether or not the connection is good at the data link layer level is transmitted / received to / from the opposite device via the cable. A communication processing unit;
With reference to a pre-registered setting value and a communication frame received from the opposite device, it is determined whether there is an erroneous connection with the opposite device at the data link layer level. A connectivity verification unit for lighting the light emitting unit;
A communication device.
The communication device according to claim 1.
A plurality of the light emitting units are provided corresponding to the plurality of ports,
The connectivity verification unit
A communication device that turns on a light emitting unit corresponding to a correct port to which the cable is to be connected so as to be different from other light emitting units when it is determined that there is an erroneous connection.
The communication device according to claim 2.
The communication device, wherein the light emitting unit is a link LED (Light Emitting Diode).
The communication device according to any one of claims 1 to 3,
The communication apparatus, wherein the communication frame is a CCM (Continuity Check Message) frame or an LLDP (Link Layer Discovery Protocol) frame.
A misconnection determination method by a communication device having a plurality of ports to which a cable for communicating with an opposite device is connected and a light emitting unit for notifying an operator whether or not there is a misconnection of the cable,
When a cable is connected to at least one of the plurality of ports, a communication frame for determining whether or not the connection is good at the data link layer level is transmitted / received to / from the opposite device via the cable. ,
With reference to a pre-registered setting value and a communication frame received from the opposite device, it is determined whether there is an erroneous connection with the opposite device at the data link layer level,
As a result of the determination, an erroneous connection determination method of lighting the light emitting unit when it is determined that there is an erroneous connection.
A computer having a plurality of ports to which a cable for communicating with the opposite device is connected, and a light emitting unit for notifying an operator whether or not there is a misconnection of the cable,
When a cable is connected to at least one of the plurality of ports, a communication frame for determining whether or not the connection is good at the data link layer level is transmitted / received to / from the opposite device via the cable. Procedure and
A procedure for determining whether or not there is an erroneous connection with the opposite device at the data link layer level with reference to a pre-registered setting value and a communication frame received from the opposite device;
As a result of the determination, a computer-readable recording medium storing a program for executing a procedure for turning on the light emitting unit when it is determined that there is an erroneous connection.