Patent Publication Number: US-2022239528-A1

Title: Relay device, vehicle, communication method, and communication program

Description:
TECHNICAL FIELD 
     The present disclosure relates to a relay device, a vehicle, a communication method, and a communication program. 
     This application claims priority on Japanese Patent Application No. 2019-142205 filed on Aug. 1, 2019, the entire content of which is incorporated herein by reference. 
     BACKGROUND ART 
     PATENT LITERATURE 1 (Japanese Laid-Open Patent Publication No. 2017-212728) discloses a network hub as below. That is, the network hub is a network hub connected to a bus of a first network and to a second network in an in-vehicle network system that includes the first network where transmission of first-type frames relating to traveling control of a vehicle is performed through a bus in accordance with a first communication protocol, and the second network where transmission of second-type frames is performed in accordance with a second communication protocol different from the first communication protocol. The network hub includes: a first reception buffer; a second reception buffer; a first transmission buffer; a second transmission buffer; a first reception unit that sequentially receives the first-type frames from the bus and stores data in the first-type frames into the first reception buffer; a second reception unit that sequentially receives the second-type frames from the second network and stores data in the second-type frames into the second reception buffer; a selection unit that selects the first network or the second network that is the destination of data being the content of either one of the first reception buffer and the second reception buffer, stores the data into the first transmission buffer when having selected the first network, and stores the data into the second transmission buffer when having selected the second network; and a transmission unit that transmits yet-to-be transmitted data in the first transmission buffer and yet-to-be transmitted data in the second transmission buffer. The transmission unit performs priority transmission control in which yet-to-be transmitted data in a priority transmission buffer being one of the first transmission buffer and the second transmission buffer is transmitted with priority over yet-to-be transmitted data in a non-priority transmission buffer, which is the other one. 
     CITATION LIST 
     Patent Literature 
     PATENT LITERATURE 1: Japanese Laid-Open Patent Publication No. 2017-212728 
     SUMMARY OF INVENTION 
     (1) A relay device of the present disclosure is installed in a vehicle and configured to relay information transmitted and received between a function unit connected to a first transmission path and a function unit connected to a second transmission path. The relay device includes: an acquisition unit configured to acquire second function unit information of the function unit connected to the second transmission path, the second function unit information being function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer; and a conversion unit configured to perform a conversion process of converting the second function unit information acquired by the acquisition unit into information that is able to be registered into a database of one or a plurality of pieces of first function unit information being function unit information of one or a plurality of the function units each connected to a corresponding first transmission path. 
     (8) A relay device of the present disclosure is installed in a vehicle. The relay device includes: a communication unit configured to perform first communication being communication according to a first communication protocol, and second communication being communication according to a second communication protocol; and a generation unit configured to generate, on the basis of network information that is used in the second communication, network information to be used in the first communication. 
     (11) A communication method of the present disclosure is to be performed in a relay device installed in a vehicle and configured to relay information transmitted and received between a function unit connected to a first transmission path and a function unit connected to a second transmission path. The communication method includes the steps of: acquiring second function unit information of the function unit connected to the second transmission path, the second function unit information being function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer; and performing a conversion process of converting the acquired second function unit information into information that is able to be registered into a database of one or a plurality of pieces of first function unit information of one or a plurality of the function units each connected to a corresponding first transmission path, the first function unit information being function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer. 
     (12) A communication program of the present disclosure is to be used in a relay device installed in a vehicle and configured to relay information transmitted and received between a function unit connected to a first transmission path and a function unit connected to a second transmission path. The communication program is for causing a computer to function as: an acquisition unit configured to acquire second function unit information of the function unit connected to the second transmission path, the second function unit information being function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer; and a conversion unit configured to perform a conversion process of converting the second function unit information acquired by the acquisition unit into information that is able to be registered into a database of one or a plurality of pieces of first function unit information of one or a plurality of the function units each connected to a corresponding first transmission path, the first function unit information being function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer. 
     One mode of the present disclosure can be realized as a semiconductor integrated circuit that realizes a part or the entirety of the relay device or can be realized as a system that includes the relay device. One mode of the present disclosure can be realized as a semiconductor integrated circuit that realizes a part or the entirety of a system including the relay device, or can be realized as a program for causing a computer to execute process steps in the system including the relay device. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  shows a configuration of a communication system according to an embodiment of the present disclosure. 
         FIG. 2  shows an example of a configuration of a vehicle communication system according to the embodiment of the present disclosure. 
         FIG. 3  shows an example of a configuration of a relay device according to the embodiment of the present disclosure. 
         FIG. 4  shows another example of the configuration of the relay device according to the embodiment of the present disclosure. 
         FIG. 5  shows an example of a configuration of a new network in the vehicle communication system according to the embodiment of the present disclosure. 
         FIG. 6  shows an example of a configuration of a new network in the vehicle communication system according to the embodiment of the present disclosure. 
         FIG. 7  shows an example of a database in a storage unit of the relay device according to the embodiment of the present disclosure. 
         FIG. 8  shows an example of a database after update in the storage unit of the relay device according to the embodiment of the present disclosure. 
         FIG. 9  shows an example of a conversion table in the storage unit of the relay device according to the embodiment of the present disclosure. 
         FIG. 10  shows another example of the database after update in the storage unit of the relay device according to the embodiment of the present disclosure. 
         FIG. 11  shows an example of a support table in the storage unit of the relay device according to the embodiment of the present disclosure. 
         FIG. 12  shows another example of the database after update in the storage unit of the relay device according to the embodiment of the present disclosure. 
         FIG. 13  shows an example of communication that should be newly performed in a new network according to the embodiment of the present disclosure. 
         FIG. 14  shows another example of the configuration of a new network in the vehicle communication system according to the embodiment of the present disclosure. 
         FIG. 15  shows another example of communication that should be newly performed in a new network according to the embodiment of the present disclosure. 
         FIG. 16  shows another example of the configuration of a new network in the vehicle communication system according to the embodiment of the present disclosure. 
         FIG. 17  shows an example of communication stopped in a new network according to the embodiment of the present disclosure. 
         FIG. 18  is a flow chart describing an operation procedure according to which a relay device provides function unit information to another relay device in the vehicle communication system according to the embodiment of the present disclosure. 
         FIG. 19  shows an example of a sequence of a construction process of a new network in the vehicle communication system according to the embodiment of the present disclosure. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     In recent years, there has been a demand for a technology for performing transmission of various types of data between a plurality of in-vehicle networks that respectively perform communications via transmission paths in accordance with different communication protocols. 
     [Problems to be Solved by the Present Disclosure] 
     In such a system including a plurality of in-vehicle networks, a technology that enables easy use of information regarding the network configuration of function units connected to different types of transmission paths, is desired. 
     The present disclosure has been made in order to solve the above problem. An object of the present disclosure is to provide a relay device, a vehicle, a communication method, and a communication program that enable easy use of information regarding the network configuration of function units connected to different types of transmission paths in a system including a plurality of in-vehicle networks. 
     [Effects of the Present Disclosure] 
     According to the present disclosure, information regarding the network configuration of function units connected to different types of transmission paths can be easily used. 
     [Description of Embodiment of the Present Disclosure] 
     First, the contents of an embodiment of the present disclosure are listed and described. 
     (1) A relay device according to an embodiment of the present disclosure is installed in a vehicle and configured to relay information transmitted and received between a function unit connected to a first transmission path and a function unit connected to a second transmission path. The relay device includes: an acquisition unit configured to acquire second function unit information of the function unit connected to the second transmission path, the second function unit information being function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer; and a conversion unit configured to perform a conversion process of converting the second function unit information acquired by the acquisition unit into information that is able to be registered into a database of one or a plurality of pieces of first function unit information being function unit information of one or a plurality of the function units each connected to a corresponding first transmission path. 
     Thus, with this configuration in which the conversion process of converting the second function unit information of the function unit connected to the second transmission path into information that is able to be registered into the database of first function unit information of the function units connected to the first transmission paths is performed, the function unit information after the conversion can be registered into the database, and the second function unit information can be referred to and used, similar to the first function unit information. Therefore, information regarding the network configuration of function units connected to different types of transmission paths can be easily used. 
     (2) Preferably, the conversion process includes a process of applying a second element being an element of the second function unit information to a first element being an element of the first function unit information and being an element having a definition different from that of the second element. 
     With this configuration, the element of the second function unit information can be replaced with an element of the first function unit information, and the value of the element in the second function unit information can be referred to and used as the value of the element of the first function unit information. 
     (3) Preferably, the conversion process includes a process of converting a value of an element of the second function unit information in accordance with a predetermined rule. 
     With this configuration, the value, of the element of the second function unit information, converted in accordance with the predetermined rule can be referred to and used as the value of the element of the first function unit information. 
     (4) Preferably, the relay device further includes a storage unit, and the conversion process includes a process of acquiring, from the storage unit, information corresponding to the second function unit information or information based on the second function unit information. 
     With this configuration, the information corresponding to the second function unit information or the information based on the second function unit information in the storage unit can be referred to and used as the first function unit information. 
     (5) Preferably, the conversion process includes a process of changing a data size of a second element being an element of the second function unit information to a data size of a first element being an element of the first function unit information and being an element corresponding to the second element. 
     With this configuration, the element of the second function unit information after the data size has been changed can be referred to and used as an element of the first function unit information. 
     (6) Preferably, on the basis of the second function unit information acquired by the acquisition unit, the conversion unit further performs at least one of registration of the second function unit information after the conversion process into the database, and removal of the second function unit information registered in the database. 
     With this configuration, the database can be flexibly updated on the basis of the content of the second function unit information. 
     (7) Preferably, the relay device further includes a provision unit configured to provide, on the basis of the database, the second function unit information having been converted by the conversion unit, to a management unit configured to update configuration information of a network including one or a plurality of function units each connected to a corresponding first transmission path and one or a plurality of function units each connected to a corresponding second transmission path. 
     With this configuration, the second function unit information after the conversion can be used in construction of a network for which the network configuration and restriction of a layer of a lower order than the application layer are taken into consideration. 
     (8) A relay device according to the embodiment of the present disclosure is installed in a vehicle. The relay device includes: a communication unit configured to perform first communication being communication according to a first communication protocol, and second communication being communication according to a second communication protocol; and a generation unit configured to generate, on the basis of network information that is used in the second communication, network information to be used in the first communication. 
     Thus, with this configuration in which network information to be used in the first communication is generated on the basis of network information that is used in the second communication, two types of network information that are used in communication via different types of transmission paths, for example, can be registered into the same database. Accordingly, the two types of network information can be referred to and used. Therefore, information regarding the network configuration of function units connected to different types of transmission paths can be easily used. 
     (9) Preferably, the first communication protocol is Ethernet (registered trademark), and the second communication protocol is CAN (Controller Area Network) (registered trademark). 
     With this configuration, in a network in which communication according to Ethernet and communication according to CAN are performed, network information that is used in communication according to Ethernet and network information that is used in communication according to CAN can be registered into the same database. 
     (10) A vehicle according to the embodiment of the present disclosure includes the relay device. 
     With this configuration, in the vehicle including the relay device, information regarding the network configuration of function units connected to different types of transmission paths can be easily used. 
     (11) A communication method according to the embodiment of the present disclosure is to be performed in a relay device installed in a vehicle and configured to relay information transmitted and received between a function unit connected to a first transmission path and a function unit connected to a second transmission path. The communication method includes the steps of: acquiring second function unit information of the function unit connected to the second transmission path, the second function unit information being function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer; and performing a conversion process of converting the acquired second function unit information into information that is able to be registered into a database of one or a plurality of pieces of first function unit information of one or a plurality of the function units each connected to a corresponding first transmission path, the first function unit information being function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer. 
     Thus, with the method in which the conversion process of converting the second function unit information of the function unit connected to the second transmission path into information that is able to be registered into the database of first function unit information of the function units connected to the first transmission paths is performed, the second function unit information after the conversion can be registered into the database, and the second function unit information can be referred to and used, similar to the first function unit information. Therefore, information regarding the network configuration of function units connected to different types of transmission paths can be easily used. 
     (12) A communication program according to the embodiment of the present disclosure is to be used in a relay device installed in a vehicle and configured to relay information transmitted and received between a function unit connected to a first transmission path and a function unit connected to a second transmission path. The communication program is for causing a computer to function as: an acquisition unit configured to acquire second function unit information of the function unit connected to the second transmission path, the second function unit information being function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer; and a conversion unit configured to perform a conversion process of converting the second function unit information acquired by the acquisition unit into information that is able to be registered into a database of one or a plurality of pieces of first function unit information of one or a plurality of the function units each connected to a corresponding first transmission path, the first function unit information being function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer. 
     Thus, with this configuration in which the conversion process of converting the second function unit information of the function unit connected to the second transmission path into information that is able to be registered into the database of first function unit information of the function units connected to the first transmission paths is performed, the function unit information after the conversion can be registered into the database DB, and the second function unit information can be referred to and used, similar to the first function unit information. Therefore, information regarding the network configuration of function units connected to different types of transmission paths can be easily used. 
     Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference signs, and description thereof is not repeated. At least some parts of the embodiment described below may be combined as desired. 
     [Vehicle Communication System] 
       FIG. 1  shows a configuration of a communication system according to an embodiment of the present disclosure. 
     With reference to  FIG. 1 , a communication system  400  includes a server  180  and one or a plurality of vehicle communication systems  300 . Each vehicle communication system  300  is installed in a vehicle  1 . 
       FIG. 2  shows an example of a configuration of a vehicle communication system according to the embodiment of the present disclosure. 
     With reference to  FIG. 2 , the vehicle communication system  300  includes: one or a plurality of in-vehicle ECUs (Electronic Control Units)  111 ; one or a plurality of in-vehicle ECUs  112 ; and relay devices  200 A,  200 B. Specifically, the vehicle communication system  300  includes in-vehicle ECUs  111 A to  111 D as the in-vehicle ECUs  111 , and in-vehicle ECUs  112 A to  112 D as the in-vehicle ECUs  112 . Hereinafter, each of the relay devices  200 A,  200 B will also be referred to as a relay device  200 . 
     The in-vehicle ECUs  111 A to  111 D each include an application  101 . The in-vehicle ECUs  112 A to  112 D each include an application  102 . 
     More specifically, as the application  101 , the in-vehicle ECU  111 A includes an application  101 A, the in-vehicle ECU  111 B includes an application  101 B, the in-vehicle ECU  111 C includes an application  101 C, and the in-vehicle ECU  111 D includes an application  101 D. 
     As the application  102 , the in-vehicle ECU  112 A includes an application  102 A, the in-vehicle ECU  112 B includes an application  102 B, the in-vehicle ECU  112 C includes an application  102 C, and the in-vehicle ECU  112 D includes an application  102 D. 
     Each in-vehicle ECU  111  is connected to a relay device  200  via an Ethernet cable  21 . Each in-vehicle ECU  112  is connected to a relay device  200  via a CAN bus  22 . The plurality of Ethernet cables  21  are an example of a first transmission path. The CAN bus  22  is an example of a second transmission path. 
     Specifically, the in-vehicle ECU  111 A,  111 B is connected to the relay device  200 A via an Ethernet cable  21 , the in-vehicle ECU  112 A,  112 B is connected to the relay device  200 A via a CAN bus  22 , the in-vehicle ECU  111 C,  111 D is connected to the relay device  200 B via an Ethernet cable  21 , and the in-vehicle ECU  112 C,  112 D is connected to the relay device  200 B via a CAN bus  22 . 
     The relay device  200 A and the relay device  200 B are connected to each other via an Ethernet cable  21 . 
     The in-vehicle ECUs  111 A to  111 D, the in-vehicle ECUs  112 A to  112 D, and the relay devices  200 A,  200 B form a network  12 . 
     Each in-vehicle ECU  111 , each in-vehicle ECU  112 , each application  101 , and each application  102  are examples of function units that are installed in the vehicle  1  among function units in the network  12 . 
     The vehicle communication system  300  need not necessarily be provided with four in-vehicle ECUs  111  and may be provided with three or less or five or more in-vehicle ECUs  111 . The vehicle communication system  300  need not necessarily be provided with four in-vehicle ECUs  112  and may be provided with three or less or five or more in-vehicle ECUs  112 . 
     The vehicle communication system  300  need not necessarily be configured such that one application  101  is installed in one in-vehicle ECU  111 , and may be configured such that two or more applications  101  are installed in one in-vehicle ECU  111 . The vehicle communication system  300  need not necessarily be configured such that one application  102  is installed in one in-vehicle ECU  112 , and may be configured such that two or more applications  102  are installed in one in-vehicle ECU  112 . 
     The vehicle communication system  300  need not necessarily be provided with two relay devices  200 . The vehicle communication system  300  may be provided with only the relay device  200 A or the relay device  200 B, or may be provided with three or more relay devices  200 . 
     The network  12  may include, as function units, an external device that is located outside the vehicle  1  and that can communicate with a TCU described later, and an application provided in the external device. 
     The in-vehicle ECUs  111 ,  112  are, for example, a TCU (Telematics Communication unit), an automated driving ECU, an engine ECU, a sensor, a navigation device, a human machine interface, a camera, and the like. 
     Each relay device  200  is a gateway device, for example, and can relay data between a plurality of in-vehicle ECUs  111 ,  112  connected to the relay device  200 . The relay device  200  can perform a relay process in accordance with, for example, a layer  2 , and a layer  3  of a higher order than the layer  2 , and performs a relay process of a frame between in-vehicle ECUs  111 ,  112  that belong to the same VLAN, and a relay process of a frame between in-vehicle ECUs  111 ,  112  that belong to different VLANs, for example. 
     More specifically, the relay device  200  performs a relay process of a frame in accordance with a communication standard of at least one of Ethernet and CAN. Ethernet is an example of a first communication protocol, and CAN is an example of a second communication protocol. Hereinafter, a frame according to the Ethernet communication standard will be referred to as an Ethernet frame, and a frame according to the CAN communication standard will be referred to as a CAN frame. An IP packet is stored in the Ethernet frame. 
     The relay device  200  relays an Ethernet frame sent and received between in-vehicle ECUs  111  connected via Ethernet cables. The relay device  200  relays a CAN frame sent and received between in-vehicle ECUs  112  each connected via a CAN bus. 
     The relay device  200  generates a CAN frame on the basis of an Ethernet frame received from an in-vehicle ECU  111  connected thereto via an Ethernet cable, and relays the generated CAN frame to an in-vehicle ECU  112  via a CAN bus. 
     The relay device  200  generates an Ethernet frame on the basis of a CAN frame received from an in-vehicle ECU  112  connected thereto via a CAN bus, and relays the generated Ethernet frame to an in-vehicle ECU  111  via an Ethernet cable. 
     In the vehicle communication system  300 , relay of an Ethernet frame and relay of a CAN frame need not necessarily be performed in accordance with an Ethernet communication standard and a CAN communication standard, respectively. For example, relay of data may be performed in accordance with another communication standard such as FlexRay (registered trademark), MOST (Media Oriented Systems Transport) (registered trademark), or LIN (Local Interconnect Network). 
     With reference to  FIG. 1  and  FIG. 2 , a TCU being an example of the in-vehicle ECU  111 ,  112  can communicate with the server  180 . Specifically, the TCU can communicate with an external device such as the server  180  via a wireless base station device  161  by using an IP packet, for example. 
     More specifically, the TCU can perform wireless communication with the wireless base station device  161  in accordance with a communication standard such as LTE (Long Term Evolution) or 3G, for example. 
     Specifically, for example, in a case where an in-vehicle ECU  111  is a TCU, when the wireless base station device  161  has received an IP packet via an external network  170  from the server  180 , the wireless base station device  161  causes the received IP packet to be included in a radio signal, and transmits the radio signal to the TCU. 
     For example, when the TCU has received, from the wireless base station device  161 , the radio signal including the IP packet from the server  180 , the TCU acquires the IP packet from the received radio signal, stores the acquired IP packet into an Ethernet frame, and transmits the Ethernet frame to the relay device  200 . 
     Meanwhile, when the TCU has received an Ethernet frame from the relay device  200 , the TCU acquires an IP packet from the received Ethernet frame, causes the acquired IP packet to be included in a radio signal, and transmits the radio signal to the wireless base station device  161 . 
     Upon receiving the radio signal from the TCU, the wireless base station device  161  acquires the IP packet from the received radio signal, and transmits the acquired IP packet to the server  180  via the external network  170 . 
     An automated driving ECU being an example of the in-vehicle ECU  111 ,  112  can communicate with another in-vehicle ECU  111 ,  112  via a relay device  200 , and performs detection of the travelling state of the vehicle  1  by using measurement information from a sensor, and automated driving control based on the detection result, for example. 
     Each application  101 ,  102  performs a process of an application layer, for example, thereby performing a predetermined process in the in-vehicle ECU  111 ,  112  in which the application  101 ,  102  is installed. For example, an application  101 ,  102  in a temperature sensor being an example of the in-vehicle ECU  111 ,  112  generates, in a predetermined cycle, temperature information indicating the outside air temperature of the vehicle  1 . 
     [Relay Device] 
       FIG. 3  shows an example of a configuration of a relay device according to the embodiment of the present disclosure.  FIG. 3  shows a configuration of the relay device  200 A. 
     With reference to  FIG. 3 , the relay device  200 A includes communication ports  121 A,  121 B,  121 C,  121 D,  122 , a relay unit  210 , a detection unit  220 , an acquisition unit  230 , a conversion unit  240 , a provision unit  250 , and a storage unit  260 . The storage unit  260  is a flash memory, for example. 
       FIG. 4  shows another example of the configuration of the relay device according to the embodiment of the present disclosure.  FIG. 4  shows a configuration of the relay device  200 B. 
     With reference to  FIG. 4 , the relay device  200 B includes an update unit  270  and a notification unit  280  instead of the provision unit  250 , when compared with the relay device  200 A. 
     The communication ports  121 A,  121 B,  121 C,  121 D are each a terminal to which an Ethernet cable  21  can be connected, for example. Hereinafter, each of the communication ports  121 A,  121 B,  121 C,  121 D will also be referred to as a communication port  121 . 
     The communication port  122  is a terminal to which a CAN bus  22  can be connected, for example. 
     In the example shown in  FIG. 2  and  FIG. 3 , in the relay device  200 A, the relay device  200 B is connected to the communication port  121 A, the in-vehicle ECU  111 A is connected to the communication port  121 B, the in-vehicle ECU  111 B is connected to the communication port  121 C, and the in-vehicle ECU  112 A and the in-vehicle ECU  112 B are connected to the communication port  122 . 
     In the example shown in  FIG. 2  and  FIG. 4 , in the relay device  200 B, the relay device  200 A is connected to the communication port  121 A, the in-vehicle ECU  111 C is connected to the communication port  121 B, the in-vehicle ECU  111 D is connected to the communication port  121 C, and the in-vehicle ECU  112 C and the in-vehicle ECU  112 D are connected to the communication port  122 . 
     [Relay Unit] 
     The relay unit  210  relays information that is transmitted and received between in-vehicle ECUs  111 ,  112 . The relay unit  210  performs communication according to Ethernet and communication according to CAN. The relay unit  210  is an example of a communication unit. 
     (Example 1 of Relay Process) 
     The relay unit  210  relays information that is transmitted and received between in-vehicle ECUs  111  connected to Ethernet cables  21 . 
     More specifically, for example, when the relay unit  210  has received, from a certain in-vehicle ECU  111  via a corresponding communication port  121 , an Ethernet frame addressed to an in-vehicle ECU  111  connected to the relay device  200  to which the relay unit  210  belongs, the relay unit  210  relays the received Ethernet frame to the destination in-vehicle ECU  111  via a corresponding communication port  121 . 
     When the relay unit  210  has received, from a certain in-vehicle ECU  111  via a corresponding communication port  121 , an Ethernet frame addressed to an in-vehicle ECU  111  connected to another relay device  200 , the relay unit  210  relays the received Ethernet frame to the other relay device  200  via the communication port  121 A. 
     When the relay unit  210  has received, from another relay device  200  via the communication port  121 A, an Ethernet frame addressed to an in-vehicle ECU  111  connected to the relay device  200  to which the relay unit  210  belongs, the relay unit  210  relays the received Ethernet frame to the destination in-vehicle ECU  111  via a corresponding communication port  121 . 
     (Example 2 of Relay Process) 
     The relay unit  210  relays information that is transmitted and received between in-vehicle ECUs  112  each connected to a CAN bus  22 . 
     More specifically, for example, when the relay unit  210  has received, from a certain in-vehicle ECU  112  via the communication port  122 , a CAN frame addressed to an in-vehicle ECU  112  connected to the relay device  200  to which relay unit  210  belongs, the relay unit  210  relays the received CAN frame to the destination in-vehicle ECU  112  via the communication port  122 . 
     When the relay unit  210  has received, from a certain in-vehicle ECU  112  via the communication port  122 , a CAN frame addressed to an in-vehicle ECU  112  connected to another relay device  200 , the relay unit  210  acquires data from the received CAN frame and generates an Ethernet frame that includes the acquired data. Then, the relay unit  210  relays the generated Ethernet frame to the other relay device  200  via the communication port  121 A. 
     When the relay unit  210  has received, from another relay device  200  via the communication port  121 A, an Ethernet frame addressed to an in-vehicle ECU  112  connected to the relay device  200  to which the relay unit  210  belongs, the relay unit  210  acquires data from the received Ethernet frame and generates a CAN frame that includes the acquired data. Then, the relay unit  210  relays the generated CAN frame to the destination in-vehicle ECU  112  via the communication port  122 . 
     (Example 3 of Relay Process) 
     The relay unit  210  relays information that is transmitted and received between an in-vehicle ECU  111  connected to an Ethernet cable  21  and an in-vehicle ECU  111  connected to a CAN bus  22 . 
     More specifically, for example, when the relay unit  210  has received, from a certain in-vehicle ECU  111  via a corresponding communication port  121 , an Ethernet frame addressed to an in-vehicle ECU  112  connected to the relay device  200  to which the relay unit  210  belongs, the relay unit  210  acquires data from the received Ethernet frame and generates a CAN frame that includes the acquired data. Then, the relay unit  210  relays the generated CAN frame to the destination in-vehicle ECU  112  via the communication port  122 . 
     When the relay unit  210  has received, from a certain in-vehicle ECU  112  via the communication port  122 , a CAN frame addressed to an in-vehicle ECU  111  connected to the relay device  200  to which the relay unit  210  belongs, the relay unit  210  acquires data from the received CAN frame and generates an Ethernet frame that includes the acquired data. Then, the relay unit  210  relays the generated Ethernet frame to the destination in-vehicle ECU  111  via a corresponding communication port  121 . 
     When the relay unit  210  has received, from a certain in-vehicle ECU  111  via a corresponding communication port  121 , an Ethernet frame addressed to an in-vehicle ECU  112  connected to another relay device  200 , the relay unit  210  relays the received Ethernet frame to the other relay device  200  via the communication port  121 A. 
     When the relay unit  210  has received, from a certain in-vehicle ECU  112  via the communication port  122 , a CAN frame addressed to an in-vehicle ECU  111  connected to another relay device  200 , the relay unit  210  acquires data from the received CAN frame and generates an Ethernet frame that includes the acquired data. Then, the relay unit  210  relays the generated Ethernet frame to the other relay device  200  via the communication port  121 A. 
     [Detection Unit] 
     The detection unit  220  detects at least one of addition of a new function unit and removal of a function unit in the network  12 . 
     More specifically, the detection unit  220  detects a function unit such as an in-vehicle ECU  111 ,  112 , an external device, or an application  101 ,  102  that is newly added to the network  12 , as a new function unit. In addition, when a function unit such as an in-vehicle ECU  111 ,  112 , an external device, or an application  101 ,  102  has been removed from the network  12 , the detection unit  220  detects that the function unit has been removed. 
     For example, periodically or non-periodically, the detection unit  220  broadcasts, via the relay unit  210 , a search message for detecting in-vehicle ECUs  111 ,  112  in the network  12 . 
     Each in-vehicle ECU  111 ,  112  in the network  12  receives the search message from the detection unit  220 , and transmits, as a response to the received search message, connection information that includes the ID, e.g., the MAC address, of the in-vehicle ECU  111 ,  112 . 
     The detection unit  220  receives the connection information from the in-vehicle ECU  111 ,  112  via the relay unit  210 , and detects addition of a new in-vehicle ECU  111 ,  112  and removal of an in-vehicle ECU  111 ,  112  on the basis of the received connection information. 
     The in-vehicle ECU  111 ,  112  that is newly added to the network  12  may be configured to transmit, to the relay device  200 , connection request information for requesting communication connection in the network  12 . 
     In this case, the detection unit  220  receives the connection request information via the relay unit  210 , and detects the transmission source in-vehicle ECU  111 ,  112  of the connection request information. 
     Hereinafter, the network  12  that includes a new function unit and the network  12  from which a function unit has been removed will also be referred to as a new network, and the network  12  before a new function unit is added and the network  12  before a function unit is removed will also be referred to as an existing network. 
     (Detection Example 1) 
       FIG. 5  shows an example of a configuration of a new network in the vehicle communication system according to the embodiment of the present disclosure. 
     With reference to  FIG. 5 , assumed is a case where an in-vehicle ECU  112 E is connected to a relay device  200  via a CAN bus  22 , whereby the in-vehicle ECU  112 E is newly added to the network  12 . The in-vehicle ECU  112 E includes an application  102 E. 
     The in-vehicle ECU  112 E is connected to a CAN bus  22  that is connected to the communication port  122  of the relay device  200 A, for example. 
     The in-vehicle ECU  112 E receives a search message from the detection unit  220  in the relay device  200 A, and transmits, as a response to the received search message, connection information that includes the ID, e.g., the MAC address, of the in-vehicle ECU  112 E to the detection unit  220  in the relay device  200 A. 
     More specifically, the in-vehicle ECU  112 E generates a CAN frame that includes connection information and transmits the generated CAN frame to the relay device  200 A. 
     When the detection unit  220  in the relay device  200 A has received the CAN frame transmitted from the in-vehicle ECU  112 E, the detection unit  220  performs an authentication process regarding the in-vehicle ECU  112 E by using the ID or the like included in the received CAN frame. 
     When the detection unit  220  has succeeded in authentication of the in-vehicle ECU  112 E, the detection unit  220  generates a CAN frame that is addressed to the in-vehicle ECU  112 E and that includes authentication success information indicating that the authentication has been successful, and transmits the generated CAN frame to the in-vehicle ECU  112 E via the relay unit  210 . 
     (Detection Example 2) 
       FIG. 6  shows an example of a configuration of a new network in the vehicle communication system according to the embodiment of the present disclosure. 
     With reference to  FIG. 6 , assumed is a case where an in-vehicle ECU  111 E is connected to a relay device  200  via an Ethernet cable  21 , whereby the in-vehicle ECU  111 E is newly added to the network  12 . The in-vehicle ECU  111 E includes an application  101 E. 
     The in-vehicle ECU  111 E is connected to the communication port  121 D in the relay device  200 A via an Ethernet cable  21 , for example. 
     The in-vehicle ECU  111 E receives a search message from the detection unit  220  in the relay device  200 A, and transmits, as a response to the received search message, connection information that includes the ID, e.g., the MAC address, of the in-vehicle ECU  111 E to the detection unit  220  in the relay device  200 A. 
     More specifically, the in-vehicle ECU  111 E generates an Ethernet frame that includes connection information and transmits the generated Ethernet frame to the relay device  200 A. 
     When the detection unit  220  in the relay device  200 A has received the Ethernet frame transmitted from the in-vehicle ECU  111 E, the detection unit  220  performs an authentication process regarding the in-vehicle ECU  111 E by using the ID or the like included in the received Ethernet frame. 
     When the detection unit  220  has succeeded in authentication of the in-vehicle ECU  111 E, the detection unit  220  generates an Ethernet frame that is addressed to the in-vehicle ECU  111 E and that includes authentication success information indicating that the authentication has been successful, and transmits the generated Ethernet frame to the in-vehicle ECU  111 E via the relay unit  210 . 
     When the detection unit  220  has succeeded in authentication of an in-vehicle ECU  111 ,  112  being a new function unit as described above, the detection unit  220  outputs, to the acquisition unit  230 , detection information indicating the ID of the in-vehicle ECU  111 ,  112 . 
     The new function unit detected by the detection unit  220  is not limited to an in-vehicle ECU  111 ,  112  that is newly connected to the relay device  200 . For example, the detection unit  220  may be configured to detect, as a new function unit, an application  101 ,  102  that is installed to an in-vehicle ECU  111 ,  112  in an existing network. 
     [Acquisition Unit] 
     With reference to  FIG. 3  and  FIG. 4  again, the acquisition unit  230  acquires function unit information F 1 , of each in-vehicle ECU  111  connected to an Ethernet cable  21 , that includes information regarding a network configuration of a layer of a lower order than the application layer. The function unit information F 1  is an example of first function unit information. 
     The acquisition unit  230  acquires function unit information F 2 , of each in-vehicle ECU  112  connected to a CAN bus  22 , that includes information regarding a network configuration of a layer of a lower order than the application layer. The function unit information F 2  is an example of second function unit information. 
     More specifically, the acquisition unit  230  acquires function unit information F 1  of the in-vehicle ECU  111  and function unit information F 2  of the in-vehicle ECU  112  indicated by the detection information received from the detection unit  220 , and acquires function unit information F 1  of each in-vehicle ECU  111  and function unit information F 2  of each in-vehicle ECU  112  in the existing network. 
     For example, as the function unit information F 1 , F 2 , the acquisition unit  230  acquires information that allows recognition of at least one of: information that allows recognition of the topology of the new network and the specifications of hardware devices such as the in-vehicle ECUs  111 ,  112 , the relay devices  200 , and the external device in the new network; restriction regarding disposition of the applications  101 ,  102  in the hardware devices in the new network; and restriction of the communication method in the new network. 
     As the information that allows recognition of the topology of the new network and the specifications of hardware devices, the acquisition unit  230  acquires at least one type of information from among: for example, information regarding the identifier, the name, the device type indicating a sensor type, a function, etc., the memory size, the number of physical ports provided for each communication protocol, the identifier of each physical port, the power supply configuration, the power consumption, the IDs of VLANs, the subnet address, and the function domain, of each hardware device; information regarding the specification of a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit) installed in each hardware device; information regarding the connection relationship between hardware devices; information regarding the bandwidth of communication between hardware devices; and information regarding the specification of the relay device  200 . 
     As the information that allows recognition of the restriction regarding disposition of the applications  101 ,  102  in the hardware devices, the acquisition unit  230  acquires at least one type of information from among, for example, pieces of information regarding the calculation speed necessary for execution, the memory use amount, restriction of the OS (Operating System) environment, and restriction of the communication protocol such as TCP (Transmission Control Protocol) and UDP (User datagram Protocol), of each application  101 ,  102 . 
     As information that allows recognition of the restriction of the communication method in the new network, the acquisition unit  230  acquires at least one type of information from among pieces of information regarding: the communication traffic; presence or absence of support of LAG (Link Aggregation); the communication frequency; necessity or unnecessity of burst transmission; the allowable delay time; the allowable amount of loss; the required security level; operation timing; the communication type indicating, e.g., periodic communication or non-periodic communication; the identifier of the application  101 ,  102  to serve as a communication counterpart; and the messaging system indicating a request-response type, a publish-subscribe type, or the like, of each application  101 ,  102 ; as well as the priority of communication by the application  101 ,  102 . 
     For example, periodically, each in-vehicle ECU  111  transmits, to the relay device  200 , a function unit information frame FA 1  being an Ethernet frame that includes a time stamp and function unit information F 1  of the in-vehicle ECU  111 . The in-vehicle ECU  111  periodically transmits the function unit information frame FA 1  to the relay device  200  in accordance with LLDP (Link Layer Discovery Protocol), for example. 
     For example, the acquisition unit  230  transmits, to each in-vehicle ECU  112  via the relay unit  210 , information request notification RA indicating that function unit information F 2  should be transmitted. 
     The in-vehicle ECU  112  transmits, as a response to the information request notification RA received from the acquisition unit  230 , a function unit information frame FA 2  being a CAN frame that includes a time stamp and function unit information F 2  of the in-vehicle ECU  112 , to the acquisition unit  230 . 
     For example, the storage unit  260  includes a database of function unit information F 1  of one or a plurality of in-vehicle ECUs  111 . 
     When the acquisition unit  230  has received a function unit information frame FA 1  from an in-vehicle ECU  111  via the relay unit  210 , the acquisition unit  230  acquires function unit information F 1  from the received function unit information frame FA 1 . The acquisition unit  230  registers the acquired function unit information F 1  into the database in the storage unit  260  for each in-vehicle ECU  111 . 
     When the acquisition unit  230  has received a function unit information frame FA 2  from an in-vehicle ECU  112  via the relay unit  210 , the acquisition unit  230  outputs the received function unit information frame FA 2  to the conversion unit  240 . 
     [Conversion Unit] 
     The conversion unit  240  is an example of a generation unit that generates network information that is used in communication according to Ethernet, e.g., function unit information F 1 , on the basis of network information that is used in communication according to CAN, e.g., function unit information F 2 . 
     More specifically, when the conversion unit  240  has received a function unit information frame FA 2  from the acquisition unit  230 , the conversion unit  240  performs a conversion process of converting the function unit information F 2  included in the received function unit information frame FA 2  into information that is able to be registered into the database of function unit information F 1  in the storage unit  260 . 
       FIG. 7  shows an example of a database in the storage unit of the relay device according to the embodiment of the present disclosure. 
     With reference to  FIG. 7 , for example, the function unit information F 1  of each in-vehicle ECU  111  connected to the relay device  200 A via an Ethernet cable  21  is registered, for each in-vehicle ECU  111 , in the database DB in the storage unit  260  of the relay device  200 A. 
     Specifically, for example, as the function unit information F 1  of the in-vehicle ECU  111 A, the database DB has registered therein “0x04” being the ID of the in-vehicle ECU  111 A, “G function” being the function of the in-vehicle ECU  111 A, “True” indicating that Ethernet being the communication protocol complied with by the in-vehicle ECU  111 A has LAG support, “0x1A” being the ID of the in-vehicle ECU  111 C being the data transmission destination of the in-vehicle ECU  111 A, and “ 20 ” indicating the communication traffic from the in-vehicle ECU  111 A to the in-vehicle ECU  111 C. “0x” means that the numerical value following “0x” is in the hexadecimal notation. 
     For example, the function unit information F 2  in the function unit information frame FA 2  received by the conversion unit  240  from the acquisition unit  230  includes transmission source information indicating the transmission source ID of the function unit information F 2 , ECU function information indicating the function of the in-vehicle ECU  112  being the transmission source of the function unit information F 2 , and state information indicating the state of the in-vehicle ECU  112  being the transmission source of the function unit information F 2 . 
     The conversion unit  240  converts various types of information included in the function unit information frame FA 2  received from the acquisition unit  230  into information that is able to be registered into the database DB, and registers the various types of information after the conversion, into the database DB. 
     (Example 1 of Conversion Process) 
     As a conversion process, the conversion unit  240  performs a process of applying an element E 2  of function unit information F 2  to an element E 1  being an element of function unit information F 1  and being an element having a definition different from the element E 2 . 
     The conversion unit  240  acquires function unit information F 2  of the in-vehicle ECU  112 A from a function unit information frame FA 2  received from the acquisition unit  230 . 
     For example, when the acquired function unit information F 2  includes “transmission source ID” as an element E 2  in the function unit information F 2 , the conversion unit  240  performs, as the conversion process, a process of applying “transmission source ID” being an element E 2  in the function unit information F 2  to an element E 1  of ID of the in-vehicle ECU  112 A in the function unit information F 1 . 
       FIG. 8  shows an example of a database after update in the storage unit of the relay device according to the embodiment of the present disclosure. 
     With reference to  FIG. 8 , the conversion unit  240  applies the transmission source ID being an element E 2  in the function unit information F 2  of the in-vehicle ECU  112 A, to the element E 1  of ID of the in-vehicle ECU  112  in the function unit information F 1 , and registers, into the database DB, “0x01” being the value of the transmission source ID in the function unit information F 2 , as the ID of the in-vehicle ECU  112 . 
     (Example 2 of Conversion Process) 
     As a conversion process, the conversion unit  240  converts the value of an element E 2  of function unit information F 2  in accordance with a predetermined rule. 
     The conversion unit  240  acquires function unit information F 2  of the in-vehicle ECU  112 A from a function unit information frame FA 2  received from the acquisition unit  230 . 
     For example, when the acquired function unit information F 2  includes “ECU function information” as an element E 2  in the function unit information F 2 , the conversion unit  240  performs, as the conversion process, a process of converting the function indicated by the ECU function information in the function unit information F 2 , to a corresponding function in the function unit information F 1 . 
     For example, the storage unit  260  has further stored therein a conversion table indicating a correspondence relationship between ECU function information in function unit information F 2 , and a function defined in the function unit information F 2  and a corresponding function in the function unit information F 1 . 
     The conversion table is a table that defines a conversion rule being an example of the aforementioned predetermined rule used when the value of an element E 2  in function unit information F 2  is converted. For example, in accordance with the conversion rule defined by the conversion table, the conversion unit  240  converts the value of an element E 2  in function unit information F 2  into information that is able to be registered into the database DB. 
       FIG. 9  shows an example of a conversion table in the storage unit of the relay device according to the embodiment of the present disclosure. 
     With reference to  FIG. 9 , a conversion table CT shows that, for example, when ECU function information included in function unit information F 2  is “0b00”, the function of the in-vehicle ECU  112  defined in the function unit information F 2  is “A function” and the corresponding function of the in-vehicle ECU  112  in the function unit information F 1  is “D function”. “0b” means that the numerical value following “0b” is in binary notation. 
     When the ECU function information included in the acquired function unit information F 2  is “0b01”, the conversion unit  240  identifies that the corresponding function, in the function unit information F 1 , that corresponds to the ECU function information is “D function”, on the basis of the conversion table CT in the storage unit  260 . 
       FIG. 10  shows another example of the database after update in the storage unit of the relay device according to the embodiment of the present disclosure. 
     With reference to  FIG. 10 , on the basis of the conversion table CT in the storage unit  260 , the conversion unit  240  registers, into the database DB, “D function”, which corresponds to “0b01” being the ECU function information included in the function unit information F 2  of the in-vehicle ECU  112 A and which is the corresponding function in the function unit information F 1 , as the function of the in-vehicle ECU  112 . 
     (Example 3 of Conversion Process) 
     As a conversion process, the conversion unit  240  acquires, from the storage unit  260 , information corresponding to function unit information F 2  or information based on function unit information F 2 . 
     The conversion unit  240  refers to the header field of a function unit information frame FA 2  received from the acquisition unit  230 , and identifies that the function unit information frame FA 2  is a CAN frame. 
     For example, the storage unit  260  has stored therein a support information table indicating a communication protocol that has LAG support and a communication protocol that does not have LAG support. 
       FIG. 11  shows an example of a support table in the storage unit of the relay device according to the embodiment of the present disclosure. 
     With reference to  FIG. 11 , for example, a support information table ST indicates that Ethernet has LAG support and CAN does not have LAG support. 
     When the conversion unit  240  has identified that the function unit information frame FA 2  received from the acquisition unit  230  is a CAN frame, the conversion unit  240  recognizes, on the basis of the support information table ST in the storage unit  260 , that CAN being the communication protocol complied with by the in-vehicle ECU  112 A does not have LAG support. 
       FIG. 12  shows another example of the database after update in the storage unit of the relay device according to the embodiment of the present disclosure. 
     With reference to  FIG. 12 , when the conversion unit  240  has identified, on the basis of the support information table ST in the storage unit  260 , that the communication protocol complied with by the in-vehicle ECU  112 A does not have LAG support, the conversion unit  240  registers, into the database DB, information to the effect that the communication protocol complied with by the in-vehicle ECU  112 A does not have LAG support. 
     (Example 4 of Conversion Process) 
     As a conversion process, the conversion unit  240  performs a process of changing the data size of an element E 2  in function unit information F 2  to a data size of an element E 1  being an element of function unit information F 1  and being an element corresponding to the element E 2 . 
     The conversion unit  240  acquires function unit information F 2  of the in-vehicle ECU  112 A from a function unit information frame FA 2  received from the acquisition unit  230 . 
     For example, when the acquired function unit information F 2  includes “transmission source ID” as an element E 2  in the function unit information F 2  and the value of “transmission source ID” is “0x00000001”, the conversion unit  240  performs, as the conversion process, a process of changing the data size of the element E 2  in the function unit information F 2  to a data size of an element E 1  of ID of the in-vehicle ECU  112 A in the function unit information F 1 . 
     Specifically, with reference to  FIG. 7  again, the database DB has registered therein “0x04”, which is 1 byte information indicating the ID of the in-vehicle ECU  111 A. 
     When “0x00000001” being a 4 byte value is included as the transmission source ID in the acquired function unit information F 2 , the conversion unit  240  changes, as the conversion process, the value of the transmission source ID to “0x01” being a 1 byte value. 
     With reference to  FIG. 8  again, the conversion unit  240  applies the transmission source ID being an element E 2  in the function unit information F 2  of the in-vehicle ECU  112 A to an element E 1  of ID of the in-vehicle ECU  112  in the function unit information F 1 , and registers, into the database DB, “0x01” being the value of the transmission source ID after the change of the data size, as the ID of the in-vehicle ECU  112 . 
     As for the changing process, the conversion unit  240  may not necessarily be configured to decrease the data size of the element E 2  of the function unit information F 2 , but may be configured to increase the data size of the element E 2  of the function unit information F 2 . 
     (Update of Database) 
     For example, the conversion unit  240  acquires function unit information F 2  of the in-vehicle ECU  112 A from a function unit information frame FA 2  received from the acquisition unit  230 , and removes function unit information F 2  registered in the database DB, on the basis of the acquired function unit information F 2 . 
     More specifically, the conversion unit  240  acquires function unit information F 2  of the in-vehicle ECU  112 A from a function unit information frame FA 2  received from the acquisition unit  230 . 
     For example, when the acquired function unit information F 2  includes, as an element E 2  in the function unit information F 2 , state information indicating the state of the in-vehicle ECU  112  being the transmission source of the function unit information F 2 , the conversion unit  240  removes function unit information F 2  registered in the database DB, on the basis of the state information. 
     Specifically, when the function unit information F 2  of the in-vehicle ECU  112 A includes state information indicating “passive”, the conversion unit  240  stores the time stamp included in the function unit information frame FA 2 , into the storage unit  260 . 
     Then, with reference to the time stamp in the storage unit  260 , when a predetermined time has elapsed from the reception of the function unit information frame FA 2  that includes the state information indicating “passive”, the conversion unit  240  removes function unit information F 2  of the in-vehicle ECU  112 A registered in the database DB. 
     [Provision Unit] 
     The provision unit  250  in the relay device  200 A transmits, to the relay device  200 B, function unit information F 1  and function unit information F 2  on the basis of the database DB in the storage unit  260 . 
     The relay device  200 A transmits, to the relay device  200 B, each piece of function unit information F 1  and each piece of function unit information F 2  that are registered in the database DB in the storage unit  260  of the relay device  200 A, in accordance with SNMP (Simple Network Management Protocol), for example. 
     With reference to  FIG. 2  and  FIG. 3  again, for example, the acquisition unit  230  in the relay device  200 B transmits, to the relay device  100 A via the relay unit  210 , an information request notification RB indicating that function unit information should be transmitted. 
     Upon receiving the information request notification RB from the relay device  200 B via the communication port  121 A, the relay unit  210  in the relay device  200 A outputs the received information request notification RB to the provision unit  250 . 
     Upon receiving the information request notification RB from the relay unit  210 , the provision unit  250  acquires each piece of function unit information F 1  and each piece of function unit information F 2  that are registered in the database DB in the storage unit  260 , and transmits each piece of function unit information F 1  and each piece of function unit information F 2  that have been acquired, to the relay device  200 B via the relay unit  210 . 
     The provision unit  250  in the relay device  200 B may be configured to, periodically or non-periodically, acquire each piece of function unit information F 1  and each piece of function unit information F 2  that are registered in the database DB in the storage unit  260  and transmit each piece of function unit information F 1  and each piece of function unit information F 2  that have been acquired, to the relay device  200 B via the relay unit  210 . 
     In this case, when the relay unit  210  in the relay device  200 B has received each piece of function unit information F 1  and each piece of function unit information F 2  from the relay device  200 A via the communication port  121 A, the relay unit  210  in the relay device  200 B outputs, to the acquisition unit  230 , each piece of function unit information F 1  and each piece of function unit information F 2  that have been received. 
     When the acquisition unit  230  in the relay device  200 B has acquired each piece of function unit information F 1  and each piece of function unit information F 2  from the relay unit  210 , the acquisition unit  230  in the relay device  200 B updates the database DB in the storage unit  260  by using each piece of function unit information F 1  and each piece of function unit information F 2  that have been acquired. Specifically, by using each piece of function unit information F 1  and each piece of function unit information F 2  that have been acquired, the acquisition unit  230  performs: addition of each piece of function unit information F 1  and each piece of function unit information F 2  into the database DB; change and removal of each piece of function unit information F 1  and each piece of function unit information F 2  that are registered in the database DB; and the like. 
     [Update Unit] 
     The update unit  270  in the relay device  200 B updates configuration information of the network  12  that includes one or a plurality of in-vehicle ECUs  111  each connected to an Ethernet cable  21  and one or a plurality of in-vehicle ECUs  112  each connected to a CAN bus  22 . The update unit  270  is an example of a management unit. 
     The update unit  270  generates, on the basis of the database DB in the storage unit  260 , configuration information indicating setting contents of the relay devices  200  and in-vehicles ECU  111 ,  112  for performing communication in a new network. 
     More specifically, when the database DB in the storage unit  260  has been updated by the acquisition unit  230  or the conversion unit  240 , the update unit  270  generates configuration information that indicates setting contents of the relay devices  200  and in-vehicle ECUs  111 ,  112  for allowing the relay devices  200  and the in-vehicle ECUs  111 ,  112  to perform communication of a layer  4  or a lower layer in an OSI (Open Systems Interconnection) reference model in a new network, on the basis of each piece of function unit information F 1  and each piece of function unit information F 2  that are registered in the database DB after the update and in consideration of a logical configuration and a physical configuration of the new network. 
     (Update Example 1) 
     With reference to  FIG. 5  again, for example, assumed is a case where the database DB in the storage unit  260  of the relay device  200 B has been updated by each piece of function unit information F 1  and each piece of function unit information F 2  in a new network in which the in-vehicle ECU  112 E has been connected to the relay device  200 A via a CAN bus  22 . 
     For example, on the basis of each piece of function unit information F 1  and each piece of function unit information F 2  in the database DB after the update, the update unit  270  recognizes communication paths to be used in communication that should be newly performed in the new network to which the in-vehicle ECU  112 E has been added, and the communication traffic in each communication path in the new network. 
       FIG. 13  shows an example of communication that should be newly performed in a new network according to the embodiment of the present disclosure.  FIG. 13  shows communication paths to be used in communication that should be newly performed in the new network to which the in-vehicle ECU  112 E has been added, and the communication traffic in each communication path in the new network. 
     With reference to  FIG. 13 , on the basis of each piece of function unit information F 1  and each piece of function unit information F 2  in the database DB after the update, the update unit  270  recognizes that when, among communications in communication paths R 11 , R 12 , R 13 , communications in the communication paths R 11 , R 13  that require relay between the relay device  200 A and the relay device  200 B are started, the communication traffic between the relay device  200 A and the relay device  200 B increases by  20 . 
     In the following, the upper limit of the band usable amount between the relay device  200 A and the relay device  200 B is assumed to be  100 . In addition, for example, the band use amount between the relay device  200 A and the relay device  200 B in the existing network shown in  FIG. 5  is assumed to be  70 . 
     When communications in the communication paths R 11 , R 13  have been started, whereby the communication traffic between the relay device  200 A and the relay device  200 B has increased by  20 , the total of the band use amounts in the relay device  200 A and the relay device  200 B in the new network becomes  90 , which is not greater than  100  serving as the upper limit value. Therefore, the update unit  270  determines that communications in the communication paths R 11 , R 13  can be performed. 
     Then, the update unit  270  generates configuration information indicating various setting contents of the relay devices  200  and the in-vehicle ECUs  111 ,  112  for newly performing communications in the communication paths R 11 , R 12 , R 13  in the new network. 
     The update unit  270  outputs the generated configuration information to the notification unit  280 , and registers the generated configuration information into the storage unit  260 . 
     Upon receiving the configuration information from the update unit  270 , the notification unit  280  notifies, on the basis of the received configuration information, at least one of the relay device  200 A and the in-vehicle ECUs  111 ,  112  in the new network of the setting content for performing communication in the new network. 
     For example, on the basis of the configuration information received from the update unit  270 , the notification unit  280  notifies the relay device  200 A and the in-vehicle ECUs  111 A,  111 C,  112 C,  112 E for which setting change is necessary, of the setting contents. When there is no in-vehicle ECU  111 ,  112  for which setting change is necessary in the new network, the notification unit  280  does not perform notification of setting contents to the relay device  200 A and the in-vehicle ECUs  111 ,  112 , for example. 
     Upon being notified of the setting contents from the notification unit  280 , the relay device  200 A and the in-vehicle ECUs  111 A,  111 C,  112 C,  112 E in the new network perform various setting changes in accordance with the notified setting contents. The relay device  200 B performs various setting changes on the basis of the generated configuration information. The relay devices  200  and the in-vehicle ECUs  111 ,  112  in the new network perform communication with each other in accordance with the setting contents after the change. 
     (Update Example 2) 
       FIG. 14  shows another example of the configuration of a new network in the vehicle communication system according to the embodiment of the present disclosure. 
     With reference to  FIG. 14 , the following case is assumed. That is, as a result of an in-vehicle ECU  112 F having been connected to the relay device  200 B via a CAN bus  22  in the network  12  shown in  FIG. 5 , the in-vehicle ECU  112 F is newly added to the network  12 , and the database DB in the storage unit  260  of the relay device  200 B is updated by each piece of function unit information F 1  and each piece of function unit information F 2  in the new network to which the in-vehicle ECU  112 F has been added. The in-vehicle ECU  112 F includes an application  102 F. 
     For example, on the basis of each piece of function unit information F 1  and each piece of function unit information F 2  in the database DB after the update, the update unit  270  recognizes communication paths to be used in communication that should be newly performed in the new network to which the in-vehicle ECU  112 F has been added, and the communication traffic in each communication path in the new network. 
       FIG. 15  shows another example of communication that should be newly performed in a new network according to the embodiment of the present disclosure.  FIG. 15  shows communication paths to be used in communication that should be newly performed in the new network to which the in-vehicle ECU  112 F has been added, and the communication traffic in each communication path in the new network. 
     With reference to  FIG. 15 , on the basis of each piece of function unit information F 1  and each piece of function unit information F 2  in the database DB after the update, the update unit  270  recognizes that when, among communications in communication paths R 14 , R 15 , communication in the communication path R 15  that requires relay between the relay device  200 A and the relay device  200 B is started, the band use amount between the relay device  200 A and the relay device  200 B increases by 20. 
     Here, as described above, the band use amount between the relay device  200 A and the relay device  200 B in the network  12  shown in  FIG. 5  is 90. 
     When communication in the communication path R 15  has been started, whereby the band use amount between the relay device  200 A and the relay device  200 B has increased by 20, the total of the band use amounts between the relay device  200 A and the relay device  200 B in the new network becomes 110, which exceeds 100 serving as the upper limit value. Therefore, the update unit  270  determines that communication using the communication path R 15  cannot be performed. 
     Then, the update unit  270  generates configuration information indicating various setting contents of the relay devices  200  and the in-vehicle ECUs  111 ,  112  for newly performing communication in the communication path R 14  in the new network. In addition, the update unit  270  registers communication using the communication path R 15  as suspension communication, into the storage unit  260 . 
     The update unit  270  outputs the generated configuration information to the notification unit  280 , and registers the generated configuration information into the storage unit  260 . 
     (Update Example 3) 
       FIG. 16  shows another example of the configuration of a new network in the vehicle communication system according to the embodiment of the present disclosure. 
     With reference to  FIG. 16 , assumed is a case where the in-vehicle ECU  111 B has been removed from the network  12  shown in  FIG. 14  and the database DB in the storage unit  260  of the relay device  200 B has been updated by each piece of function unit information F 1  and each piece of function unit information F 2  in the new network after the removal. 
     For example, on the basis of each piece of function unit information F 1  and each piece of function unit information F 2  in the database DB after the update, the update unit  270  recognizes communication paths having been used in communication that is stopped in the new network from which the in-vehicle ECU  111 B has been removed, and the communication traffic in each communication path in the new network. 
       FIG. 17  shows an example of communication stopped in a new network according to the embodiment of the present disclosure.  FIG. 17  shows communication paths, in the new network from which the in-vehicle ECU  111 B has been removed, that have been used in communications that are stopped due to the removal of the in-vehicle ECU  111 B, and the communication traffic in each communication path in the new network. 
     With reference to  FIG. 17 , on the basis of each piece of function unit information F 1  and each piece of function unit information F 2  in the database DB after the update, the update unit  270  recognizes that when communications between communication paths R 1 , R 2  that require relay between the relay device  200 A and the relay device  200 B are stopped, the band use amount between the relay device  200 A and the relay device  200 B decreases by  30 . 
     Here, as described above, the band use amount between the relay device  200 A and the relay device  200 B in the network  12  shown in  FIG. 14  is 90. 
     The update unit  270  recognizes that when communications in the communication paths R 1 , R 2  have been stopped, whereby the band use amount between the relay device  200 A and the relay device  200 B has decreased by 30, the total of the band use amounts between the relay device  200 A and the relay device  200 B in the new network becomes 60. 
     In addition, when communication in the communication path R 15 , which is the suspension communication registered in the storage unit  260 , has been started, whereby the band use amount between the relay device  200 A and the relay device  200 B has increased by 20, the total of the band use amounts between the relay device  200 A and the relay device  200 B in the new network becomes  80 , which is not greater than  100  as the upper limit value. Therefore, the update unit  270  determines that communication in the communication path R 15  can be performed. 
     Then, the update unit  270  generates configuration information indicating various setting contents of the relay devices  200  and the in-vehicle ECUs  111 ,  112  for newly performing communication in the communication path R 15  in the new network, with communications in the communication path R 1 , R 2  stopped. 
     The update unit  270  outputs the generated configuration information to the notification unit  280  and registers the generated configuration information into the storage unit  260 . 
     [Operation Flow] 
     Each device in the communication system according to the embodiment of the present disclosure includes a computer that includes a memory. An arithmetic processing unit such as a CPU in the computer reads out, from the memory, a program including a part or all of steps in the flow chart and sequence shown below, and executes the program. Programs of the plurality of devices can each be installed from outside. The programs of the plurality of devices are each distributed in a state of being stored in a storage medium. 
       FIG. 18  is a flow chart describing an operation procedure according to which a relay device provides function unit information to another relay device in the vehicle communication system according to the embodiment of the present disclosure. 
     With reference to  FIG. 18 , first, the relay device  200 A waits for function unit information from an in-vehicle ECU  111 ,  112  in the network  12  (NO in step S 102 ). When the relay device  200 A has received function unit information (YES in step S 102 ), the relay device  200 A determines whether or not the received function unit information is function unit information F 1  of an in-vehicle ECU  111  connected to an Ethernet cable  21  (step S 104 ). 
     When the received function unit information is function unit information F 1  (YES in step S 104 ), the relay device  200 A registers the received function unit information F 1  into the database DB in the storage unit  260  (step S 108 ). 
     Meanwhile, when the received function unit information is not function unit information F 1 , e.g., when the received function unit information is function unit information F 2  of an in-vehicle ECU  112  connected to a CAN bus  22  (NO in step S 104 ), the relay device  200 A converts the received function unit information F 2  into information that is able to be registered into the database DB of function unit information F 1  in the storage unit  260  (step S 106 ). 
     Next, the relay device  200 A registers the function unit information F 2  after the conversion into the database DB (step S 108 ). 
     Next, the relay device  200 A acquires each piece of function unit information F 1  and each piece of function unit information F 2  that are registered in the database DB, and transmits each piece of function unit information F 1  and each piece of function unit information F 2  that have been acquired, to the relay device  200 B (step S 110 ). 
     Next, the relay device  200 A waits for function unit information from an in-vehicle ECU  111 ,  112  in the network  12  (NO in step S 102 ). 
       FIG. 19  shows an example of a sequence of a construction process of a new network in the vehicle communication system according to the embodiment of the present disclosure. 
     With reference to  FIG. 19 , first, the in-vehicle ECU  111 A connected to the relay device  200 A via an Ethernet cable  21  transmits function unit information F 1  of the in-vehicle ECU  111 A to the relay device  200 A (step S 202 ). 
     Next, the relay device  200 A registers the function unit information F 1  received from the in-vehicle ECU  111 A into the database DB in the storage unit  260  (step S 204 ). 
     Next, the in-vehicle ECU  112 E that is newly added to the network  12  by being connected to the relay device  200 A via a CAN bus  22  transmits connection request information to the relay device  200 A (step S 206 ). 
     Next, the relay device  200 A receives the connection request information from the in-vehicle ECU  112 E, thereby detecting the in-vehicle ECU  112 E, and performs an authentication process regarding the in-vehicle ECU  112 E (step S 208 ). 
     Next, the in-vehicle ECU  112 E transmits function unit information F 2  thereof to the relay device  200 A (step S 210 ). 
     Next, the relay device  200 A converts the function unit information F 2  received from the in-vehicle ECU  111 E into information that is able to be registered into the database DB of function unit information F 1  in the storage unit  260  (step S 212 ). 
     Next, the relay device  200 A registers the function unit information F 2  after the conversion into the database DB (step S 214 ). 
     Next, the relay device  200 A acquires each piece of function unit information F 1  and each piece of function unit information F 2  that are registered in the database DB in the storage unit  260  of the relay device  200 A, and transmits each piece of function unit information F 1  and each piece of function unit information F 2  that have been acquired, to the relay device  200 B (step S 216 ). 
     Next, the relay device  200 B generates configuration information of a new network on the basis of each piece of function unit information F 1  and each piece of function unit information F 2  that are registered in the database DB in the storage unit  260  of the relay device  200 B, and each piece of function unit information F 1  and each piece of function unit information F 2  that have been received from the relay device  200 A (step S 218 ). 
     Next, on the basis of the generated configuration information, the relay device  200 B notifies the relay device  200 A and the in-vehicle ECUs  111 A,  112 E of the setting contents (step S 220 ). 
     Next, the relay device  200 A and the in-vehicle ECUs  111 A,  112 E perform various setting changes in accordance with the setting contents notified of by the relay device  200 B (step S 222 ). 
     In addition, the relay device  200 B performs various setting changes on the basis of the generated configuration information (step S 224 ). 
     Next, the relay devices  200 A,  200 B and the in-vehicle ECUs  111 A,  112 E in the new network perform communication with each other in accordance with the setting contents after the change (step S 226 ). 
     In the relay device  200  according to the embodiment of the present disclosure, the conversion unit  240  performs, as the conversion process, Examples 1, 2, 3, 4 of the conversion process described above. However, the present disclosure is not limited thereto. The conversion unit  240  may be configured not to perform a part or all of Examples 1, 2, 3, 4 of the conversion process. The conversion unit  240  may be configured to perform a conversion process other than Examples 1, 2, 3, 4 of the conversion process. 
     In the relay device  200  according to the embodiment of the present disclosure, the conversion unit  240  registers function unit information F 2  after conversion, into the database DB. However, the present disclosure is not limited thereto. The conversion unit  240  may be configured to transmit function unit information F 2  after conversion to another relay device  200  via, for example, the relay unit  210 , without registering the function unit information F 2  after conversion into the database DB. 
     In the relay device  200  according to the embodiment of the present disclosure, the conversion unit  240  converts function unit information F 2  into information that is able to be registered into the database DB in the storage unit  260  of the relay device  200 . However, the present disclosure is not limited thereto. The relay device  200  may be configured not to be provided with the storage unit  260  including the database DB. The conversion unit  240  may be configured to convert function unit information F 2  into information that is able to be registered into a database in a device other than the relay device  200 . 
     In the relay device  200  according to the embodiment of the present disclosure, the conversion unit  240  removes function unit information F 2  registered in the database DB, on the basis of function unit information F 2  acquired from a function unit information frame FA 2 . However, the present disclosure is not limited thereto. The conversion unit  240  may be configured to remove function unit information F 2  registered in the database DB, on the basis of information other than function unit information F 2 . 
     In the vehicle communication system  300  according to the embodiment of the present disclosure, the relay device  200 B includes the update unit  270  and the notification unit  280 . However, the present disclosure is not limited thereto. The relay device  200 B may be configured not to be provided with the update unit  270  and the notification unit  280 . In this case, for example, function unit information F 1  and function unit information F 2  after conversion may be used in abnormality detection or failure detection of the in-vehicle ECU  111 ,  112  in the network  12 . Alternatively, a device other than the relay devices  200 A,  200 B may include the update unit  270  and the notification unit  280 . 
     Meanwhile, in a system including a plurality of in-vehicle networks, a technology that enables easy use of information regarding the network configuration of function units connected to different types of transmission paths, is desired. 
     For example, in recent years, in association with prevalence of car sharing and a desire for improvement of processing capacities of in-vehicle devices installed in vehicles, there is a demand for customization of an in-vehicle network through addition of applications to the in-vehicle network. Thus, there is a demand for a technology that allows addition or removal of various applications with respect to an in-vehicle network in accordance with needs of a user. 
     When an application is added to or removed from an in-vehicle network to construct a new network, there are cases where communication required by a higher order layer cannot be realized due to the network configuration and restriction of a lower order layer. 
     Therefore, in a system including a plurality of in-vehicle networks, in order to flexibly construct a network having a new configuration, a technology that allows easy acquisition of information regarding a network configuration and useable in construction of a network, is desired. 
     In this regard, in the relay device  200  according to the embodiment of the present disclosure, the acquisition unit  230  acquires function unit information F 2  of an in-vehicle ECU  112  connected to a CAN bus  22 , the function unit information F 2  being function unit information that includes information regarding the network configuration of a layer of a lower order than the application layer. The conversion unit  240  performs a conversion process of converting the function unit information F 2  acquired by the acquisition unit  230  into information that is able to be registered into the database DB of function unit information F 1  of one or a plurality of in-vehicle ECUs  111  each connected to a corresponding Ethernet cable  21 . 
     Thus, with this configuration in which the conversion process of converting the function unit information F 2  of the in-vehicle ECU  112  connected to the CAN bus  22  into information that is able to be registered into the database DB of function unit information F 1  of in-vehicle ECUs  111  connected to Ethernet cables  21  is performed, the function unit information F 2  after the conversion can be registered into the database DB, and the function unit information F 2  can be referred to and used, similar to the function unit information F 1 . 
     Therefore, in the relay device  200  according to the embodiment of the present disclosure, information regarding the network configuration of function units connected to different types of transmission paths can be easily used. 
     In the relay device  200  according to the embodiment of the present disclosure, in the conversion process, a process of applying an element E 2  of the function unit information F 2  to an element E 1  being an element of function unit information F 1  and being an element having a definition different from that of the element E 2 , is performed. 
     With this configuration, the element E 2  of the function unit information F 2  can be replaced with an element E 1  of the function unit information F 1 , and the value of the element E 2  in the function unit information F 2  can be referred to and used as the value of the element E 1  of the function unit information F 1 . 
     In the relay device  200  according to the embodiment of the present disclosure, the conversion process includes a process of converting the value of the element E 2  of the function unit information F 2  in accordance with a predetermined rule. 
     With this configuration, the value, of the element E 2  of the function unit information F 2 , converted in accordance with the predetermined rule can be referred to and used as the value of the element E 1  of the function unit information F 1 . 
     In the relay device  200  according to the embodiment of the present disclosure, the conversion process includes a process of acquiring, from the storage unit  260 , information corresponding to the function unit information F 2  or information based on the function unit information F 2 . 
     With this configuration, the information corresponding to the function unit information F 2  or the information based on the function unit information F 2  in the storage unit  260  can be referred to and used as the function unit information F 1 . 
     In the relay device  200  according to the embodiment of the present disclosure, the conversion process includes a process of changing the data size of an element E 2  of the function unit information F 2  to a data size of an element E 1  being an element of the function unit information F 1  and being an element corresponding to the element E 2 . 
     With this configuration, the element E 2  of the function unit information F 2  after the data size has been changed can be referred to and used as an element E 1  of the function unit information F 1 . 
     In the relay device  200  according to the embodiment of the present disclosure, the conversion unit  240  further performs, on the basis of the function unit information F 2  acquired by the acquisition unit  230 , at least one of registration of the function unit information F 2  after the conversion process into the database DB, and removal of function unit information F 2  registered in the database DB. 
     With this configuration, the database DB can be flexibly updated on the basis of the content of the function unit information F 2 . 
     In the relay device  200  according to the embodiment of the present disclosure, the provision unit  250  provides, on the basis of the database DB, the function unit information F 2  having been converted by the conversion unit  240 , to the update unit  270  that updates configuration information of the network  12  including one or a plurality of in-vehicle ECUs  111  each connected to a corresponding Ethernet cable  21  and one or a plurality of in-vehicle ECUs  112  each connected to a corresponding CAN  22 . 
     With this configuration, the function unit information F 2  after the conversion can be used in construction of a network for which the network configuration and restriction of a layer of a lower order than the application layer are taken into consideration. 
     In the relay device  200  according to the embodiment of the present disclosure, the relay unit  210  performs first communication being communication according to a first communication protocol, and second communication being communication according to a second communication protocol. On the basis of network information that is used in the second communication, the conversion unit  240  generates network information to be used in the first communication. 
     Thus, with this configuration in which network information to be used in the first communication is generated on the basis of network information that is used in the second communication, two types of network information that are used in communication via different types of transmission paths, for example, can be registered into the same database. Therefore, the two types of network information can be referred to and used. 
     Therefore, in the relay device  200  according to the embodiment of the present disclosure, information regarding the network configuration of function units connected to different types of transmission paths can be easily used. 
     In the relay device  200  according to the embodiment of the present disclosure, the first communication protocol is Ethernet, and the second communication protocol is CAN. 
     With this configuration, in a network in which communication according to Ethernet and communication according to CAN are performed, network information that is used in communication according to Ethernet and network information that is used in communication according to CAN can be registered into the same database. 
     The vehicle  1  according to the embodiment of the present disclosure includes the relay device  200 . 
     With this configuration, in the vehicle  1  including the relay device  200 , information regarding the network configuration of function units connected to different types of transmission paths can be easily used. 
     A communication method according to the embodiment of the present disclosure is a communication method to be performed in a relay device  200  that relays information transmitted and received between an in-vehicle ECU  111  connected to an Ethernet cable  21  and an in-vehicle ECU  112  connected to a CAN bus  22 . In this communication method, first, the relay device  200  acquires function unit information F 2 , of an in-vehicle ECU  112  connected to a CAN bus  22 , that includes information regarding the network configuration of a layer of a lower order than an application layer. Next, the relay device  200  performs a conversion process of converting the acquired function unit information F 2  into information that is able to be registered into the database DB of one or a plurality of pieces of function unit information F 1 , of one or a plurality of in-vehicle ECUs  111  each connected to a corresponding Ethernet cable  21 , that includes information regarding the network configuration of a layer of a lower order than the application layer. 
     Thus, with the method in which the conversion process of converting the function unit information F 2  of the in-vehicle ECU  112  connected to a CAN bus  22  into information that is able to be registered into the database DB of function unit information F 1  of the in-vehicle ECUs  111  connected to Ethernet cables  21  is performed, the function unit information F 2  after the conversion can be registered into the database DB, and the function unit information F 2  can be referred to and used, similar to the function unit information F 1 . 
     Therefore, in the communication method according to the embodiment of the present disclosure, information regarding the network configuration of function units connected to different types of transmission paths can be easily used. 
     The above embodiment is merely illustrative in all aspects and should not be recognized as being restrictive. The scope of the present disclosure is defined by the scope of the claims rather than by the description above, and is intended to include meaning equivalent to the scope of the claims and all modifications within the scope. 
     The above description includes the features in the additional notes below. 
     [Additional Note 1] 
     A relay device installed in a vehicle, the relay device comprising: 
     a relay unit configured to relay information that is transmitted and received between an in-vehicle ECU connected to an Ethernet cable and an in-vehicle ECU connected to a CAN bus; 
     an acquisition unit configured to acquire second function unit information of the in-vehicle ECU connected to the CAN bus, the second function unit information being function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer; and 
     a conversion unit configured to perform a conversion process of converting the second function unit information acquired by the acquisition unit, so as to be able to be registered into a database of one or a plurality of pieces of first function unit information being function unit information of one or a plurality of the in-vehicles ECU each connected to a corresponding Ethernet cable. 
     [Additional Note 2] 
     A communication method to be used in a relay device configured to perform first communication being communication according to a first communication protocol, and second communication being communication according to a second communication protocol, the communication method comprising the steps of: 
     receiving network information that is used in the second communication; and 
     generating, on the basis of the received network information, network information to be used in the first communication. 
     [Additional Note 3] 
     A communication program to be used in a relay device installed in a vehicle, the communication program being for causing a computer to function as: 
     a communication unit configured to perform first communication being communication according to a first communication protocol, and second communication being communication according to a second communication protocol; and 
     a generation unit configured to generate, on the basis of network information that is used in the second communication, network information to be used in the first communication. 
     REFERENCE SIGNS LIST 
       1  vehicle 
       21  Ethernet cable (first transmission path) 
       22  CAN bus (second transmission path) 
       12  network 
       100  application 
       111  in-vehicle ECU 
       112  in-vehicle ECU 
       161  wireless base station device 
       170  external network 
       180  server 
       200  relay device 
       210  relay unit (communication unit) 
       220  detection unit 
       230  acquisition unit 
       240  conversion unit (generation unit) 
       250  provision unit 
       260  storage unit 
       270  update unit (management unit) 
       280  notification unit 
       300  vehicle communication system 
       400  communication system