Patent Publication Number: US-2022231910-A1

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

Description:
TECHNICAL FIELD 
     The present disclosure relates to a relay device, a vehicle communication system, a vehicle, a communication method, and a communication program. 
     This application claims priority on Japanese Patent Application No. 2019-142240 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. 2018-192876) discloses a driving support device as below. That is, the driving support device is a driving support device that can be connected to an intra-vehicular network that includes one or more communication buses. The driving support device includes: a message acquisition unit that acquires a communication message sent in a communication bus; a determination unit that determines whether or not an electronic control device for vehicle control is connected to the communication bus, on the basis of the communication message acquired by the message acquisition unit; and a communication control unit that stops, when the determination unit has determined that the electronic control device is connected to the communication bus, transmission of the communication message to the communication bus to which the electronic control device is connected. 
     PATENT LITERATURE 2 (Japanese Laid-Open Patent Publication No. 2017-220220) discloses a vehicular electronic control device as below. That is, the vehicular electronic control device is a vehicular electronic control device ( 1  to  5 ) that is connected to an in-vehicle network ( 6 ) and that executes a predetermined function through an installed application. The vehicular electronic control device includes: a service interface ( 8 ) that, in response to a request from the application, requests a service that uses a function installed in another vehicular electronic control device connected to the in-vehicle network, and that, upon receiving a request for a service from the other vehicular electronic control device, generates a service so as to respond thereto; a service bus ( 9 ) that transmits/receives a message that corresponds to a request of service and a response by using a predetermined protocol between the service interface and the service interface of the other vehicular electronic control device; and a service management unit ( 11 ) that allows the service to be dynamically and mutually used, by managing the position of the service. 
     CITATION LIST 
     Patent Literature 
     PATENT LITERATURE 1: Japanese Laid-Open Patent Publication No. 2018-192876 
     PATENT LITERATURE 2: Japanese Laid-Open Patent Publication No. 2017-220220 
     SUMMARY OF INVENTION 
     A relay device of the present disclosure is installed in a vehicle. The relay device includes: a detection unit configured to detect a new function unit being a function unit that is newly added to a network including an existing function unit being one or a plurality of function units; a relay unit configured to relay a frame between the function units; and an acquisition unit configured to acquire, from the frame, relayed by the relay unit, between the new function unit detected by the detection unit and the existing function unit, function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer, the function unit information being of at least one of the new function unit and the existing function unit. 
     A vehicle communication system of the present disclosure includes: a relay device installed in a vehicle; an existing function unit being one or a plurality of function units forming a network; and a new function unit being a function unit that is newly added to the network. The relay device detects addition of the new function unit to the network. The new function unit or the existing function unit transmits a frame that is addressed to another function unit and that has stored therein function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer. The relay device acquires the function unit information from the frame transmitted by the new function unit or the existing function unit. 
     A communication method of the present disclosure is to be performed in a relay device. The relay device is installed in a vehicle and configured to relay a frame between function units. The communication method includes the steps of: detecting a new function unit being a function unit that is newly added to a network including an existing function unit being one or a plurality of the function units; and acquiring, from the frame that should be relayed between the new function unit detected and the existing function unit, function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer, the function unit information being of at least one of the new function unit and the existing function unit. 
     A communication method of the present disclosure is to be performed in a vehicle communication system. The vehicle communication system includes a relay device installed in a vehicle, an existing function unit being one or a plurality of function units forming a network, and a new function unit being a function unit that is newly added to the network. The communication method includes the steps of: detecting, performed by the relay device, addition of the new function unit to the network; transmitting, performed by the new function unit or the existing function unit, a frame that is addressed to another function unit and that has stored therein function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer; and acquiring, performed by the relay device, the function unit information from the frame transmitted by the new function unit or the existing function unit. 
     A communication program of the present disclosure is to be used in a relay device installed in a vehicle. The communication program is for causing a computer to function as: a detection unit configured to detect a new function unit being a function unit that is newly added to a network including an existing function unit being one or a plurality of function units; a relay unit configured to relay a frame between the function units; and an acquisition unit configured to acquire, from the frame, relayed by the relay unit, between the new function unit detected by the detection unit and the existing function unit, function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer, the function unit information being of at least one of the new function unit and the existing function unit. 
     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. One mode of the present disclosure can be realized as a semiconductor integrated circuit that realizes a part or the entirety of the vehicle communication system. One mode of the present disclosure can be realized as a program for causing a computer to execute process steps in the vehicle communication system. 
    
    
     
       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 network configuration in the vehicle communication system according to the embodiment of the present disclosure. 
         FIG. 4  shows a configuration of a relay device  200  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 another example of the configuration of a new network in the vehicle communication system according to the embodiment of the present disclosure. 
         FIG. 7  shows another example of the configuration of a new network in the vehicle communication system according to the embodiment of the present disclosure. 
         FIG. 8  shows an example of a communication setting frame transmitted by a function unit according to the embodiment of the present disclosure. 
         FIG. 9  shows an example of configuration information generated by a generation unit according to the embodiment of the present disclosure. 
         FIG. 10  shows another example of the configuration of a new network after setting change has been performed in the vehicle communication system according to the embodiment of the present disclosure. 
         FIG. 11  is a flow chart describing an operation procedure according to which the relay device constructs a new network in the vehicle communication system according to the embodiment of the present disclosure. 
         FIG. 12  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. 
         FIG. 13  shows another example of the sequence of the construction process of a new network in the vehicle communication system according to the embodiment of the present disclosure. 
         FIG. 14  shows another example of the sequence of the 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, in association with prevalence of car sharing and a desire for improvement of processing capacities of in-vehicle devices installed in vehicles, there has been 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. 
     Problems to be Solved by the Present Disclosure 
     Exceeding the technologies described in PATENT LITERATURE 1 and 2, a technology that allows easy acquisition of information of a network when a new function unit has been added to the network, 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 communication system, a vehicle, a communication method, and a communication program that allow easy acquisition of information of a network to which a new function unit has been added. 
     Effects of the Present Disclosure 
     According to the present disclosure, information of a network to which a new function unit has been added can be easily acquired. 
     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 the embodiment of the present disclosure is installed in a vehicle. The relay device includes: a detection unit configured to detect a new function unit being a function unit that is newly added to a network including an existing function unit being one or a plurality of function units; a relay unit configured to relay a frame between the function units; and an acquisition unit configured to acquire, from the frame, relayed by the relay unit, between the new function unit detected by the detection unit and the existing function unit, function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer, the function unit information being of at least one of the new function unit and the existing function unit. 
     Thus, with this configuration in which the function unit information is acquired from the frame between function units, the function unit information can be acquired from the frame that should be relayed between the new function unit and the existing function unit in order to establish communication connection between the new function unit and the existing function unit, for example. Therefore, it is possible to acquire the function unit information without sending and receiving a frame for acquiring the function unit information between function units. Therefore, information of a network to which a new function unit has been added can be easily acquired. 
     (2) Preferably, the function unit information is information that is to be used in generation of configuration information of a new network being the network that further includes the new function unit. 
     With this configuration, it is possible to construct a new network in consideration of the network configuration and restriction of a layer of a lower order than the application layer, for example. Accordingly, for example, occurrence of delay in high importance communication due to addition of a new function unit to the network can be suppressed. 
     (3) Preferably, the acquisition unit acquires the function unit information from the frame transmitted by the new function unit and relayed to the existing function unit. 
     With this configuration, for example, the function unit information can be acquired from the frame transmitted by the new function unit that should transmit data to the existing function unit after establishment of communication connection. 
     (4) Preferably, the acquisition unit acquires the function unit information from the frame transmitted by the existing function unit and relayed to the new function unit. 
     With this configuration, for example, the function unit information can be acquired from the frame transmitted by the existing function unit that should transmit data to the new function unit after establishment of communication connection. 
     (5) Preferably, without changing transmission destination information and transmission source information that are included in the frame received from the function unit, the relay unit relays the frame to another function unit, and the acquisition unit acquires the function unit information from the frame relayed by the relay unit. 
     With this configuration, in the relay device that performs snooping on the frame between function units, the function unit information can be easily acquired. 
     (6) Preferably, the relay unit changes at least one of transmission destination information and transmission source information that are included in the frame received from the function unit, and relays the frame after having been changed, to another function unit, and the acquisition unit acquires the function unit information from the frame relayed by the relay unit. 
     With this configuration, in the relay device functioning as a proxy server, the function unit information can be easily acquired. 
     (7) Preferably, the relay device further includes a generation unit configured to generate configuration information of a new network being the network that further includes the new function unit, on the basis of the function unit information acquired by the acquisition unit. 
     With this configuration, it is possible to construct a new network in consideration of the network configuration and restriction of a layer of a lower order than the application layer, by using the function unit information. Accordingly, for example, occurrence of delay in high importance communication due to addition of a new function unit to the network can be suppressed. 
     (8) Preferably, the function unit information is information that is not to be processed in a function unit that should receive the frame. 
     With this configuration, the function unit information can be acquired from the frame without increasing the processing load in the function unit that should receive the frame. 
     (9) Preferably, the detection unit: detects, as the new function unit, at least one of an application included in an in-vehicle ECU (Electronic Control Unit) that is newly added to the network, an application that is newly installed into an in-vehicle ECU in the network, and an application included in an external device that is newly added, outside the vehicle, to the network; performs an authentication process regarding the new function unit detected; and notifies the new function unit of a result of the authentication process. 
     With this configuration, diverse new function units can be detected, and a new network can be constructed. 
     (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 of a network to which a new function unit has been added can be easily acquired. 
     (11) A vehicle communication system according to the embodiment of the present disclosure includes: a relay device installed in a vehicle; an existing function unit being one or a plurality of function units forming a network; and a new function unit being a function unit that is newly added to the network. The relay device detects addition of the new function unit to the network. The new function unit or the existing function unit transmits a frame that is addressed to another function unit and that has stored therein function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer. The relay device acquires the function unit information from the frame transmitted by the new function unit or the existing function unit. 
     Thus, with this configuration in which the function unit information is acquired from the frame transmitted by the new function unit or the existing function unit, the function unit information can be acquired from the frame that should be relayed between the new function unit and the existing function unit in order to establish communication connection between the new function unit and the existing function unit, for example. Therefore, it is possible to acquire the function unit information without sending and receiving a frame for acquiring the function unit information between function units. Therefore, information of a network to which a new function unit has been added can be easily acquired. 
     (12) A communication method according to the embodiment of the present disclosure is to be performed in a relay device. The relay device is installed in a vehicle and configured to relay a frame between function units. The communication method includes the steps of: detecting a new function unit being a function unit that is newly added to a network including an existing function unit being one or a plurality of the function units; and acquiring, from the frame that should be relayed between the new function unit detected and the existing function unit, function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer, the function unit information being of at least one of the new function unit and the existing function unit. 
     Thus, with this method in which the function unit information is acquired from the frame that should be relayed between the new function unit and the existing function unit, the function unit information can be acquired from the frame that should be relayed between the new function unit and the existing function unit in order to establish communication connection between the new function unit and the existing function unit, for example. Therefore, it is possible to acquire the function unit information without sending and receiving a frame for acquiring the function unit information between function units. Therefore, information of a network to which a new function unit has been added can be easily acquired. 
     (13) A communication method according to the embodiment of the present disclosure is to be performed in a vehicle communication system. The vehicle communication system includes a relay device installed in a vehicle, an existing function unit being one or a plurality of function units forming a network, and a new function unit being a function unit that is newly added to the network. The communication method includes the steps of: detecting, performed by the relay device, addition of the new function unit to the network; transmitting, performed by the new function unit or the existing function unit, a frame that is addressed to another function unit and that has stored therein function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer; and acquiring, performed by the relay device, the function unit information from the frame transmitted by the new function unit or the existing function unit. 
     With this method in which the function unit information is acquired from the frame transmitted by the new function unit or the existing function unit, the function unit information can be acquired from the frame that should be relayed between the new function unit and the existing function unit in order to establish communication connection between the new function unit and the existing function unit, for example. Therefore, it is possible to acquire the function unit information without sending and receiving a frame for acquiring the function unit information between function units. Therefore, information of a network to which a new function unit has been added can be easily acquired. 
     (14) A communication program according to the embodiment of the present disclosure is to be used in a relay device installed in a vehicle. The communication program is for causing a computer to function as: a detection unit configured to detect a new function unit being a function unit that is newly added to a network including an existing function unit being one or a plurality of function units; a relay unit configured to relay a frame between the function units; and an acquisition unit configured to acquire, from the frame, relayed by the relay unit, between the new function unit detected by the detection unit and the existing function unit, function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer, the function unit information being of at least one of the new function unit and the existing function unit. 
     Thus, with this configuration in which the function unit information is acquired from the frame between function units, the function unit information can be acquired from the frame that should be relayed between the new function unit and the existing function unit in order to establish communication connection between the new function unit and the existing function unit, for example. Therefore, it is possible to acquire the function unit information without sending and receiving a frame for acquiring the function unit information between function units. Therefore, information of a network to which a new function unit has been added can be easily acquired. 
     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  111 , and a relay device  200 . Specifically the vehicle communication system  300  includes in-vehicle ECU  111 A to  111 E as the in-vehicle ECUs  111 . 
     The in-vehicle ECUs  111 A to  111 E each include an application  100 . 
     More specifically, as the application  100 , the in-vehicle ECU  111 A includes an application  100 A, the in-vehicle ECU  111 B includes an application  100 B, the in-vehicle ECU  111 C includes an application  100 C, the in-vehicle ECU  111 D includes an application  100 D, and the in-vehicle ECU  111 E includes an application  100 E. 
     The in-vehicle ECUs  111 A to  111 E and the relay device  200  form a network  12 . 
     Each in-vehicle ECU  111  and each application  100  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 five in-vehicle ECUs  111  and may be provided with one, two, three, four, six, or more in-vehicle ECUs  111 . The vehicle communication system  300  need not necessarily be configured such that one application  100  is provided to one in-vehicle ECU  111 , and may be configured such that two or more applications  100  are provided to one in-vehicle ECU  111 . 
     The vehicle communication system  300  need not necessarily be provided with one relay device  200 , and may be provided with a plurality of relay devices  200 . 
     The network  12  may include, as function units, an external device that is located outside the vehicle  1 , and an application provided in the external device. 
     The in-vehicle ECUs  111  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. 
     In this example, the in-vehicle ECUs  111 A,  111 B,  111 C,  111 D,  111 E are a TCU, an automated driving ECU, an engine ECU, a temperature sensor, and a water temperature sensor, respectively. 
     Hereinafter, the in-vehicle ECUs  111 A,  111 B,  111 C,  111 D,  111 E will also be referred to as a TCU  111 A, an automated driving ECU  111 B, an engine ECU  111 C, a temperature sensor  111 D, and a water temperature sensor  111 E, respectively. 
     In the network  12 , each of the in-vehicle ECUs  111 A to  111 E is connected to the relay device  200  via an Ethernet (registered trademark) cable  11 . 
     The relay device  200  is a gateway device, for example, and can relay data between a plurality of in-vehicle ECUs  111  connected to the relay device  200 . 
     The relay device  200  performs a relay process of an Ethernet frame in accordance with an Ethernet communication standard. Specifically, the relay device  200  relays an Ethernet frame sent and received between in-vehicle ECUs  111 , for example. An IP packet is stored in the Ethernet frame. 
     In the vehicle communication system  300 , relay of an Ethernet frame need not necessarily be performed in accordance with the Ethernet communication standard. For example, relay of data may be performed in accordance with a communication standard such as CAN (Controller Area Network) (registered trademark), FlexRay (registered trademark), MOST (Media Oriented Systems Transport) (registered trademark), or LIN (Local Interconnect Network). 
     With reference to  FIG. 1  and  FIG. 2 , the TCU  111 A can communicate with the server  180 . Specifically, the TCU  111 A can communicate with the server  180  via a wireless base station device  161  by using an IP packet, for example. 
     More specifically, the TCU  111 A 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, 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  111 A. 
     For example, when the TCU  111 A has received, from the wireless base station device  161 , the radio signal including the IP packet from the server  180 , the TCU  111 A 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  111 A has received an Ethernet frame from the relay device  200 , the TCU  111 A 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  111 A, 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 . 
     The automated driving ECU  111 B can communicate with another in-vehicle ECU  111  via the 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. 
     The engine ECU  111 C can communicate with another in-vehicle ECU  111  via the relay device  200 , and controls the engine in the vehicle  1 , for example. 
     More specifically, the engine ECU  111 C acquires pieces of information that indicate, for example, the number of revolutions of the engine, the vehicle speed of the vehicle  1 , the shaft torque of the engine, the state of the transmission, the state of the throttle valve, a measurement value of each sensor, and the like, and controls the engine on the basis of the acquired information. 
     The engine ECU  111 C can transmit a part or all of the acquired information to the relay device  200 , in response to a request from the relay device  200 , for example. 
     The temperature sensor  111 D can communicate with another in-vehicle ECU  111  via the relay device  200 , and periodically measures the outside air temperature of the vehicle  1 , for example. 
     The water temperature sensor  111 E can communicate with another in-vehicle ECU  111  via the relay device  200 , and periodically measures the water temperature of cooling water circulating in the engine in the vehicle  1 , for example. 
     Each application  100  performs a process of an application layer, for example, thereby performing a predetermined process in the in-vehicle ECU  111  in which the application  100  is provided. For example, the application  100 D in the temperature sensor  111 D generates, in a predetermined cycle, temperature information indicating the outside air temperature of the vehicle  1 . 
       FIG. 3  shows an example of a network configuration in the vehicle communication system according to the embodiment of the present disclosure. 
     With reference to  FIG. 3 , the relay device  200  includes communication ports  120 A,  120 B,  120 C. Each of the communication ports  120 A,  120 B,  120 C will also be referred to as a communication port  120 . Each communication port  120  is a terminal to which an Ethernet cable  11  can be connected, for example. 
     In the example shown in  FIG. 3 , the TCU  111 A is connected to the communication port  120 A, the automated driving ECU  111 B and the engine ECU  111 C are connected to the communication port  120 B, and the temperature sensor  111 D and the water temperature sensor  111 E are connected to the communication port  120 C. 
     In the network  12 , the TCU  111 A belongs to a VLAN (Virtual Local Area Network)  10 . The automated driving ECU  111 B and the engine ECU  111 C belong to a VLAN  20  different from the VLAN  10 . The temperature sensor  111 D and the water temperature sensor  111 E belong to a VLAN  30  different from the VLAN  10  and the VLAN  20 . 
     The relay device  200  performs a relay process of an Ethernet frame between in-vehicle ECUs  111  that belong to the same VLAN, for example. Specifically, on the basis of the transmission source MAC (Media Access Control) address and the transmission destination MAC address that are included in a received Ethernet frame, the relay device  200  transmits the Ethernet framed to the transmission destination in-vehicle ECU  111 . 
     The relay device  200  performs a relay process of an IP packet between in-vehicle ECUs  111  that belong to different VLANs, for example. Specifically, the relay device  200  acquires an IP packet from a received Ethernet frame, and transmits the IP packet to the transmission destination in-vehicle ECU  111  on the basis of the transmission destination IP address of the acquired IP packet. 
     [Relay Device] 
       FIG. 4  shows a configuration of the relay device  200  according to the embodiment of the present disclosure. 
     With reference to  FIG. 4 , the relay device  200  includes the communication ports  120 A,  120 B,  120 C, a relay unit  220 , a detection unit  230 , an acquisition unit  240 , a generation unit  250 , a notification unit  260 , and a storage unit  270 . The storage unit  270  is a flash memory, for example. Hereinafter, each of the communication ports  120 A,  120 B,  120 C will also be referred to as a communication port  120 . 
     The relay unit  220 , the detection unit  230 , the acquisition unit  240 , the generation unit  250 , and the notification unit  260  are each realized by a processor such as a CPU (Central Processing Unit), a DSP (Digital Signal Processor), or the like, for example. 
     [Relay Unit] 
     The relay unit  220  relays a frame between in-vehicle ECUs  111 . Specifically, for example, when the relay unit  220  has received an Ethernet frame from a certain in-vehicle ECU  111  via a corresponding communication port  120 , the relay unit  220  performs a relay process of a layer  2  and a relay process of a layer  3  with respect to the received Ethernet frame. 
     For example, without changing transmission destination information and transmission source information that are included in a frame received from an in-vehicle ECU  111 , the relay unit  220  relays the frame to another in-vehicle ECU  111 . 
     Specifically, for example, when the relay unit  220  has received, from the automated driving ECU  111 B belonging to the VLAN  20 , an Ethernet frame addressed to the engine ECU  111 C belonging to the VLAN  20 , the relay unit  220  performs, without changing the transmission destination MAC address and the transmission source MAC address that are included in the received Ethernet frame, the relay process to the engine ECU  111 C in accordance with the transmission destination MAC address and the transmission source MAC address. 
     Alternatively, the relay unit  220  changes at least one of the transmission destination information and the transmission source information that are included in the frame received from the in-vehicle ECU  111 , and relays the frame after having been changed, to another in-vehicle ECU  111 . 
     As an example, when the relay unit  220  has received, from the temperature sensor  111 D belonging to the VLAN  30 , an Ethernet frame addressed to the engine ECU  111 C belonging to the VLAN  20 , for example, the relay unit  220  changes the transmission destination MAC address and the transmission source MAC address that are included in the received Ethernet frame, and relays the Ethernet frame after having been changed, to the destination engine ECU  111 C. 
     As another example, when the relay unit  220  has received an Ethernet frame from an in-vehicle ECU  111 , the relay unit  220  changes at least one of the transmission destination IP address and the transmission source IP address that are included in the received Ethernet frame, and relays the Ethernet frame after having been changed, to another in-vehicle ECU  111 . 
     Specifically, for example, the relay unit  220  functions as a proxy of the transmission source in-vehicle ECU  111  for an Ethernet frame. More specifically, when the relay unit  220  has received an Ethernet frame from the water temperature sensor  111 E, the relay unit  220  changes the transmission source IP address included in the received Ethernet frame to the IP address of the relay unit  220 , and relays the Ethernet frame after having been changed, to the engine ECU  111 C. 
     Then, when, as a response to the Ethernet frame, the relay unit  220  has received, from the engine ECU  111 C, an Ethernet frame that has the IP address of the relay unit  220  as the transmission destination IP address, the relay unit  220  changes the transmission destination IP address included in the received Ethernet frame to the IP address of the water temperature sensor  111 E, and relays the Ethernet frame after having been changed, to the water temperature sensor  111 E. 
     The relay unit  220  may be configured to change information that is included in the frame received from an in-vehicle ECU  111  and that is stored in a field other than those of the transmission destination information and the transmission source information, and to relay the frame after having been changed, to another in-vehicle ECU  111 . 
     [Detection Unit] 
     The detection unit  230  detects a new function unit being a function unit that is newly added to the network  12 . More specifically, the detection unit  230  detects, as a new function unit, a function unit, such as an in-vehicle ECU  111 , an external device, and an application  100 , that is newly added to the network  12 . As an example, the detection unit  230  detects, as a new ECU, an in-vehicle ECU  111  that is newly added to the network  12 . 
     For example, the new function unit transmits, to the relay device  200 , connection request information for requesting communication connection in the network  12 . 
     The detection unit  230  receives the connection request information via the relay unit  220  to detect the new function unit being the transmission source of the connection request information. 
     The detection unit  230  may be configured to broadcast, for example, periodically, a search message for detecting a new function unit. In this case, the new function unit receives the search message and transmits the aforementioned connection request information as a response to the received search message. 
     Hereinafter, the network  12  that includes a new function unit will also be referred to as a new network, the network  12  before a new function unit is added will also be referred to an existing network, and each function unit included in the existing network will also be referred to as an existing function unit. Each in-vehicle ECU  111  included in the existing network is an example of the existing function unit, i.e., an existing ECU. 
       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 , a case where an in-vehicle ECU  111 G is newly added to the network  12  is assumed. In this example, the in-vehicle ECU  111 G is an image sensor. Hereinafter, the in-vehicle ECU  111 G will also be referred to as an image sensor  111 G. The image sensor  111 G includes an application  100 G being a new function unit. 
     When the image sensor  111 G has been supplied with power and connected to the communication port  120 C in the relay device  200  via an Ethernet cable  11 , for example, the image sensor  111 G transmits connection request information for requesting communication connection in the network  12 , to the detection unit  230  in the relay device  200 . 
     More specifically, the application  100 G in the image sensor  111 G generates an Ethernet frame that includes connection request information, the ID of the application  100 G, and the MAC address of the relay device  200  as the transmission destination MAC address, and transmits the generated Ethernet frame to the relay device  200 . 
     When the detection unit  230  in the relay device  200  has received the Ethernet frame transmitted from the application  100 G, the detection unit  230  performs an authentication process regarding the application  100 G by using the ID and the like included in the received Ethernet frame. 
     When the detection unit  230  has succeeded in authentication of the application  100 G, the detection unit  230  generates an Ethernet frame that includes authentication success information indicating that the authentication has been successful, and the MAC address of the image sensor  111 G as the transmission destination MAC address, and transmits the generated Ethernet frame to the image sensor  111 G via the relay unit  220 . 
     The new function unit that is detected by the detection unit  230  is not limited to an application  100  included in an in-vehicle ECU  111  that is newly connected to the relay device  200 . For example, the detection unit  230  may be configured to detect, as a new function unit, an application  100  that is installed in an in-vehicle ECU  111  in the existing network. 
       FIG. 6  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. 6 , a case where an application  100 H is newly installed as a new function unit into the engine ECU  111 C in the network  12  is assumed. 
     When the application  100 H has been installed in the engine ECU  111 C, the application  100 H generates an Ethernet frame that includes connection request information, the ID of the application  100 H, and the MAC address of the relay device  200  as the transmission destination MAC address, and transmits the generated Ethernet frame to the relay device  200 . 
     When the detection unit  230  in the relay device  200  has received the Ethernet frame transmitted from the application  100 H, the detection unit  230  performs an authentication process regarding the application  100 H by using the ID and the like included in the received Ethernet frame. 
     When the detection unit  230  has succeeded in authentication of the application  100 H, the detection unit  230  generates an Ethernet frame that includes authentication success information indicating that the authentication has been successful, and the MAC address of the engine ECU  111 C as the transmission destination MAC address, and transmits the generated Ethernet frame to the engine ECU  111 C via the relay unit  220 . 
     The new function unit that is detected by the detection unit  230  is not limited to an application  100  included in an in-vehicle ECU  111  that is newly connected to the relay device  200 , or an application  100  that is installed into an in-vehicle ECU  111 . For example, the detection unit  230  may be configured to detect, as a new function unit, an application  100  included in an external device  113  that is added, outside the vehicle  1 , to the network  12 . 
       FIG. 7  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. 7 , a case where the external device  113  is newly added to the network  12  is assumed. The external device  113  is a device that is provided outside the vehicle  1 . The external device  113  includes an application  100 J being a new function unit. 
     The external device  113  can communicate with the TCU  111 A. More specifically, the external device  113  can communicate with the TCU  111 A via the wireless base station device  161  by using an IP packet, for example. 
     The external device  113  transmits connection request information for requesting communication connection in the network  12 , to the detection unit  230  in the relay device  200  via the TCU  111 A. 
     More specifically, the application  100 J in the external device  113  transmits an IP packet that includes connection request information, the ID of the application  100 J, and the MAC address of the relay device  200 , to the wireless base station device  161  via the external network  170 . 
     When the wireless base station device  161  has received the IP packet via the external network  170  from the external device  113 , 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  111 A. 
     When the TCU  111 A has received, from the wireless base station device  161 , the radio signal including the IP packet from the application  100 J, the TCU  111 A acquires the IP packet from the received radio signal, generates an Ethernet frame that includes the acquired IP packet and the MAC address of the relay device  200  as the transmission destination MAC address, and transmits the generated Ethernet frame to the relay device  200 . 
     When the detection unit  230  in the relay device  200  has received the Ethernet frame from the TCU  111 A, the detection unit  230  performs an authentication process regarding the application  100 J by using the ID and the like included in the IP packet stored in the received Ethernet frame. 
     When the detection unit  230  has succeeded in authentication of the application  100 J, the detection unit  230  generates an Ethernet frame that includes authentication success information indicating that the authentication has been successful, and the MAC address of the external device  113  as the transmission destination MAC address, and transmits the generated Ethernet frame to the TCU  111 A. 
     When the TCU  111 A has received the Ethernet frame from the detection unit  230 , the TCU  111 A 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 external device  113  via the wireless base station device  161 . 
     When the detection unit  230  has succeeded in authentication of a new function unit as described above, the detection unit  230  stores the ID, e.g., the MAC address, of the new function unit into the storage unit  270 . 
     [Communication Connection between Function Units] 
     For example, periodically or non-periodically, a new function unit and an existing function unit each transmit a discovery frame for detecting another function unit, to one or a plurality of other function units via the relay device  200 . In addition, for example, periodically or non-periodically, a new function unit and an existing function unit each generate a communication setting frame being a frame for establishing communication connection with another function unit, and transmit the generated communication setting frame to one or a plurality of other function units via the relay device  200 . 
       FIG. 8  shows an example of a communication setting frame transmitted by a function unit according to the embodiment of the present disclosure. 
     With reference to  FIG. 8 , the communication setting frame has a header, a transmission source IP address, a transmission destination IP address, an option field, a data field, and an additional information field. The data field has stored therein at least one of information that indicates the content of data that the transmission source function unit can transmit, and information that indicates the content of data that the transmission source function unit should receive. 
     For example, in accordance with a protocol such as SOME/IP (Scalable Service-Oriented Middleware on Ethernet/Internet Protocol), a new function unit and an existing function unit each generate a communication setting frame in which information indicating the content of data that the corresponding function unit itself can transmit is stored in the data field, and transmit the generated communication setting frame to one or a plurality of other function units via the relay device  200 . 
     Alternatively, in accordance with a protocol such as SOME/IP, a new function unit and an existing function unit each generate a communication setting frame in which information indicating the content of data that the corresponding function unit itself should receive is stored in the data field, and transmit the generated communication setting frame to one or a plurality of other function units via the relay device  200 . 
     With reference to  FIG. 5  again, as an example, when the image sensor  111 G including the application  100 G being a new function unit has received authentication success information from the relay device  200 , the image sensor  111 G generates a communication setting frame in which information indicating that the image sensor  111 G can transmit image data around the vehicle  1  is stored in the data field. Then, via the relay device  200 , the image sensor  111 G broadcasts the generated communication setting frame to all of the existing function units in the network  12  or multicasts the generated communication setting frame to specific existing function units. 
     When the automated driving ECU  111 B including the application  100 B being one of the existing function units in the network  12  has received the communication setting frame from the image sensor  111 G, the automated driving ECU  111 B generates a communication setting frame in which request information indicating that the automated driving ECU  111 B should receive the image data and the IP address of the automated driving ECU  111 B are stored in the data field, and transmits, as a response to the communication setting frame from the image sensor  111 G, the generated communication setting frame to the image sensor  111 G via the relay device  200 . 
     The image sensor  111 G and the automated driving ECU  111 B establish communication connection by sending and receiving the communication setting frames and the like. After the image sensor  111 G has established communication connection with the automated driving ECU  111 B, the image sensor  111 G periodically or non-periodically transmits image data to the automated driving ECU  111 B via the relay device  200 . 
     Meanwhile, when an existing function unit other than the automated driving ECU  111 B in the network  12  has received the communication setting frame from the image sensor  111 G, the existing function unit generates a communication setting frame in which information indicating that image data is not necessary is stored in the data field, and transmits, as a response to the communication setting frame from the image sensor  111 G, the generated communication setting frame to the image sensor  111 G via the relay device  200 . 
     With reference to  FIG. 6  again, as another example, when the engine ECU  111 C including the application  100 H being an installed new function unit has received authentication success information from the relay device  200 , the engine ECU  111 C generates a communication setting frame in which request information indicating that the engine ECU  111 C should receive water temperature data of cooling water circulating in the engine in the vehicle  1  is stored in the data field. Then, via the relay device  200 , the engine ECU  111 C broadcasts the generated communication setting frame to all of the existing function units in the network  12  or multicasts the generated communication setting frame to specific existing function units. 
     When the water temperature sensor  111 E including the application  100 E being one of the existing function units in the network  12  has received the communication setting frame from the engine ECU  111 C, the water temperature sensor  111 E generates a communication setting frame in which information indicating that the water temperature sensor  111 E can transmit water temperature data and the IP address of the water temperature sensor  111 E are stored in the data field, and transmits, as a response to the communication setting frame from the engine ECU  111 C, the generated communication setting frame to the engine ECU  111 C via the relay device  200 . 
     The water temperature sensor  111 E and the engine ECU  111 C establish communication connection by sending and receiving the communication setting frames and the like. After the water temperature sensor  111 E has established communication connection with the engine ECU  111 C, the water temperature sensor  111 E periodically or non-periodically transmits water temperature data to the engine ECU  111 C via the relay device  200 . 
     Meanwhile, when an existing function unit other than the water temperature sensor  111 E in the network  12  has received the communication setting frame from the engine ECU  111 C, the existing function unit generates a communication setting frame in which information indicating that the existing function unit cannot transmit water temperature data is stored in the data field, and transmits, as a response to the communication setting frame from the engine ECU  111 C, the generated communication setting frame to the engine ECU  111 C via the relay device  200 . 
     [Acquisition Unit] 
     The acquisition unit  240  acquires, from a frame that is relayed between a new function unit and an existing function unit by the relay unit  220 , function unit information that includes information regarding the network configuration of a layer of a lower order than the application layer, the function unit information being of at least one of the new function unit and the existing function unit. 
     More specifically, at least one of the new function unit and the existing function unit transmits a communication setting frame in which function unit information is stored in the additional information field, to another function unit via the relay device  200 . 
     Specifically, among the new function unit and the existing function units that transmit/receive communication setting frames, a publish function unit being a function unit that will, after establishment of communication connection realized by transmission/reception of the communication setting frames and the like, periodically or non-periodically transmit data by using the established communication connection, transmits, to another function unit, a communication setting frame in which function unit information is stored in the additional information field. 
     As an example, the image sensor  111 G including the application  100 G being a new function unit is a publish function unit: that transmits, to existing function units, a communication setting frame in which information indicating that the image sensor  111 G can transmit image data around the vehicle  1  is stored in the data field; and that will, after establishment of communication connection with another function unit, periodically or non-periodically transmit image data by using the established communication connection. Thus, the image sensor  111 G broadcasts or multicasts, to existing function units, a communication setting frame in which function unit information is stored in the additional information field. 
     Meanwhile, the automated driving ECU  111 B including the application  100 B being one of the existing function units in the network  12  is a subscribe function unit: that transmits, to the image sensor  111 G, as a response to the communication setting frame from the image sensor  111 G, a communication setting frame in which request information indicating that the automated driving ECU  111 B should receive image data is stored in the data field; and that will not, after establishment of communication connection with the image sensor  111 G, perform data transmission using the established communication connection. Thus, the automated driving ECU  111 B transmits the communication setting frame to the image sensor  111 G, without storing function unit information into the additional information field. 
     As another example, the engine ECU  111 C including the application  100 H being a new function unit is a subscribe function unit: that transmits, to existing function units, a communication setting frame in which request information indicating that the engine ECU  111 C should receive water temperature data is stored in the data field; and that will not, after establishment of communication connection with another function unit, perform data transmission using the established communication connection. Thus, the engine ECU  111 C broadcasts or multicasts the communication setting frame to existing function units, without storing function unit information into the additional information field. 
     Meanwhile, the water temperature sensor  111 E including the application  100 E being one of the existing function units in the network  12  is a publish function unit: that transmits, to the engine ECU  111 C, as a response to the communication setting frame from the engine ECU  111 C, a communication setting frame in which information indicating that the water temperature sensor  111 E can transmit water temperature data is stored in the data field; and that will, after establishment of communication connection with the engine ECU  111 C, periodically or non-periodically transmit water temperature data by using the established communication connection. Thus, the water temperature sensor  111 E transmits, to the engine ECU  111 C, the communication setting frame in which function unit information is stored in the additional information field. 
     (Specific Example of Function Unit Information) 
     For example, the function unit information is information that is not to be processed in a function unit that should receive a communication setting frame. More specifically, a function unit that has received a communication setting frame does not perform a process of acquiring function unit information from the additional information field in the communication setting frame, a calculation process using the function unit information, and various setting changing processes using the function unit information. For example, the function unit information is information that is to be used in generation of configuration information of a new network. 
     For example, as the function unit information, the new function unit and the existing function unit each store, into the additional information field in a communication setting frame, 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 , the relay device  200 , and the external device  113  in the new network; restriction regarding disposition of the applications  100  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 new function unit and the existing function unit each store, into the additional information field in the communication setting frame, at least one type of information from among: for example, information regarding the identifier, the name, the device type indicating a sensor type, 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 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  100  in the hardware devices, the new function unit and the existing function unit each store, into the additional information field in a communication setting frame, 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  100 . 
     As information that allows recognition of the restriction of the communication method in the new network, the new function unit and the existing function unit each store, into the additional information field of a communication setting frame, at least one type of information from among pieces of information regarding: the communication data size; 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  100  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  100 ; as well as the priority of communication by the application  100 . 
     The new function unit and the existing function unit may each store one piece of function unit information into the additional information field in a communication setting frame, or may store a plurality of pieces of function unit information into the additional information field in a communication setting frame. 
     For example, the new function unit and the existing function unit each store, into the additional information field, information indicating the type of function unit information and information indicating the value of the function unit information. As an example, the new function unit and the existing function unit each store, into the additional information field, information indicating that the function unit information stored in the additional information field is the communication frequency, and “ 20  times/second” indicating the value of the communication frequency. 
     When the relay unit  220  has received a communication setting frame from the new function unit to the existing function unit, the relay unit  220  stores the received communication setting frame into the storage unit  270 . When the relay unit  220  has received a communication setting frame from the existing function unit to the new function unit, the relay unit  220  stores the received communication setting frame into the storage unit  270 . 
     Then, for example, as described above, the relay unit  220  acquires a communication setting frame from the storage unit  270 , and relays the acquired communication setting frame to the transmission destination function unit, without changing transmission destination information and transmission source information that are included in the acquired communication setting frame. Accordingly, it is possible to acquire the function unit information from the frame relayed by the relay unit  220 , without increasing the processing load in the relay unit  220 . 
     Alternatively, as described above, the relay unit  220  acquires a communication setting frame from the storage unit  270 , changes at least one of transmission destination information and transmission source information that are included in the acquired communication setting frame, and relays the frame after having been changed, to the transmission destination function unit. 
     More specifically, other than the two examples as described above, for example, the relay unit  220  receives a communication setting frame that has been broadcast or multicast from one or a plurality of function units, and changes the transmission destination MAC address of the received communication setting frame to a transmission destination MAC address corresponding to a specific communication port  120 , thereby limiting the transmission destination function unit of the communication setting frame that has been broadcast or multicast. Accordingly, improvement of security and reduction of the data amount of a frame subjected to the relay process by the relay unit  220  can be realized. 
     The acquisition unit  240  monitors the storage unit  270 . When a communication setting frame is stored into the storage unit  270  by the relay unit  220 , the acquisition unit  240  acquires function unit information from the additional information field in the communication setting frame stored in the storage unit  270 . 
     That is, for example, the acquisition unit  240  acquires function unit information from at least one of a communication setting frame from the new function unit to the existing function unit and a communication setting frame from the existing function unit to the new function unit. 
     The acquisition unit  240  outputs one or a plurality of pieces of function unit information having been acquired, to the generation unit  250 . 
     [Generation Unit] 
     The generation unit  250  generates configuration information of a new network on the basis of the one or plurality of pieces of function unit information received from the acquisition unit  240 . 
     More specifically, the generation unit  250  generates configuration information indicating the setting contents of the existing function unit and the new function unit for performing communication in the new network. 
     For example, on the basis of the one or plurality of pieces of function unit information received from the acquisition unit  240 , the generation unit  250  generates configuration information that indicates the setting content of each function unit for performing communication of a layer 4 or lower layer in an OSI (Open Systems Interconnection) reference model in a new network, in consideration of the logical configuration and the physical configuration of the new network. 
       FIG. 9  shows an example of configuration information generated by the generation unit according to the embodiment of the present disclosure. 
     In the following, for convenience, the port numbers of the communication ports  120 A,  120 B,  120 C of the relay device  200  are defined as “1”, “2”, “3”, respectively. In addition, it is assumed that each in-vehicle ECU  111  includes one communication port and the port number of the communication port is defined as “1”. 
     With reference to  FIG. 9 , for example, in the new network shown in  FIG. 5 , the generation unit  250  generates configuration information that indicates the content of: setting “VLAN  20 ” as the ID of the VLAN to which the image sensor  111 G including the application  100 G being a new function unit belongs; and additionally setting “VLAN  20 ” as the ID of the VLAN that corresponds to the communication port  120 C of the relay device  200  including an application  100 F. 
     The generation unit  250  outputs the generated configuration information to the notification unit  260 , and registers the generated configuration information into the storage unit  270 . 
     When the notification unit  260  has received the configuration information from the generation unit  250 , the notification unit  260  notifies, on the basis of the received configuration information, at least one of the function units 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 generation unit  250 , the notification unit  260  notifies, via the relay unit  220 , a function unit for which setting change is necessary, of the setting content. When there is no function unit for which setting change is necessary in the new network, the notification unit  260  does not perform notification of the setting content to a function unit, for example. In the example shown in  FIG. 9 , for example, the notification unit  260  allocates an IP address that corresponds to the VLAN  20  to the image sensor  111 G including the application  100 G, and notifies the image sensor  111 G of the allocated IP address. 
     When each function unit in the new network has been notified of the setting content from the notification unit  260 , the function unit performs various setting changes in accordance with the notified setting content. The function units in the new network perform communication with each other in accordance with the setting contents after having been changed. 
       FIG. 10  shows another example of the configuration of a new network after setting change has been performed in the vehicle communication system according to the embodiment of the present disclosure. 
     With reference to  FIG. 10 , in the new network shown in  FIG. 5 , the image sensor  111 G and the relay device  200  perform setting change by using the setting contents notified of from the notification unit  260 . As a result, the image sensor  111 G becomes able to perform communication in the VLAN  20 . 
     [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. 11  is a flow chart describing an operation procedure according to which the relay device constructs a new network in the vehicle communication system according to the embodiment of the present disclosure. 
     With reference to  FIG. 11 , first, the relay device  200  waits for addition of a new function unit to the network  12  (NO in step S 102 ). Upon detecting a new function unit (YES in step S 102 ), the relay device  200  performs an authentication process regarding the detected new function unit (step S 104 ). 
     Next, the relay device  200  waits for a communication setting frame that should be relayed between the new function unit and an existing function unit (NO in step S 106 ). Upon receiving a communication setting frame from the new function unit or an existing function unit (YES in step S 106 ), the relay device  200  acquires function unit information of the transmission source function unit from the received communication setting frame (step S 108 ). 
     Next, the relay device  200  relays the received communication setting frame to the transmission destination function unit (step S 110 ). 
     Next, on the basis of the acquired function unit information, the relay device  200  generates configuration information of a new network (step S 112 ). 
     Next, on the basis of the generated configuration information, the relay device  200  notifies one or a plurality of function units in the new network of a setting content (step S 114 ). 
     Next, the relay device  200  waits for addition of a new function unit to the new network (NO in step S 102 ). 
     The order of steps S 108  and S 110  is not limited to the above, and may be switched with each other. 
       FIG. 12  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.  FIG. 12  shows a sequence of a construction process of a new network in which a new function unit and existing function units A, B can transmit/receive data bidirectionally. 
     With reference to  FIG. 12 , first, the new function unit that is newly added to the network  12  transmits connection request information to the relay device  200  (step S 202 ). 
     Next, the relay device  200  receives the connection request information from the new function unit to detect the new function unit, and performs an authentication process regarding the new function unit (step S 204 ). 
     Next, the new function unit transmits, to the relay device  200 , a communication setting frame that is addressed to the existing function units A, B, and that has stored therein: information indicating the content of data that the new function unit should receive and the content of data that new function unit can transmit; and function unit information of the new function unit (step S 206 ). 
     Next, when the relay device  200  has received, from the new function unit, the communication setting frame addressed to the existing function units A, B, the relay device  200  acquires the function unit information from the received communication setting frame (step S 208 ). 
     Next, the relay device  200  relays the communication setting frame received from the new function unit, to the existing function units A, B (step S 210 ). 
     Next, the existing function unit A transmits, to the relay device  200 , a communication setting frame that is addressed to the new function unit and that has stored therein: information indicating the content of data that the existing function unit A should receive and the content of data that the existing function unit A can transmit; and function unit information (step S 212 ). 
     Next, when the relay device  200  has received, from the existing function unit A, the communication setting frame addressed to the new function unit, the relay device  200  acquires the function unit information from the received communication setting frame (step S 214 ). 
     Next, the relay device  200  relays the communication setting frame received from the existing function unit A, to the new function unit (step S 216 ). 
     Next, the existing function unit B transmits, to the relay device  200 , a communication setting frame that is addressed to the new function unit and that has stored therein: information indicating the content of data that the existing function unit B should receive and the content of data that the existing function unit B can transmit; and function unit information of the existing function unit B (step S 218 ). 
     Next, when the relay device  200  has received, from the existing function unit B, the communication setting frame addressed to the new function unit, the relay device  200  acquires the function unit information from the received communication setting frame (step S 220 ). 
     Next, the relay device  200  relays the communication setting frame received from the existing function unit B, to the new function unit (step S 222 ). 
     Next, on the basis of each piece of the acquired function unit information, the relay device  200  generates configuration information of a new network (step S 224 ). 
     Next, on the basis of the generated configuration information, the relay device  200  notifies the new function unit and the existing function units A, B of setting contents (step S 226 ). 
     Next, the new function unit performs various setting changes in accordance with the setting content notified of from the relay device  200  (step S 228 ). 
     The existing function units A, B perform various setting changes in accordance with the setting contents notified of from the relay device  200  (step S 230 ). 
     Next, the new function unit and the existing function units A, B in the new network perform communication with each other in accordance with the setting contents after having been changed (step S 232 ). 
       FIG. 13  shows another example of the sequence of the construction process of a new network in the vehicle communication system according to the embodiment of the present disclosure.  FIG. 13  shows a sequence of a construction process of a new network in which the existing function units A, B being publish function units can transmit data to a new function unit being a subscribe function unit. 
     With reference to  FIG. 13 , first, the new function unit that is newly added to the network  12  transmits connection request information to the relay device  200  (step S 302 ). 
     Next, the relay device  200  receives the connection request information from the new function unit to detect the new function unit, and performs an authentication process regarding the new function unit (step S 304 ). 
     Next, the new function unit transmits, to the relay device  200 , a communication setting frame that is addressed to the existing function units A, B and that has stored therein: information indicating the content of data that the new function unit should receive; and function unit information of the new function unit (step S 306 ). 
     Next, when the relay device  200  has received, from the new function unit, the communication setting frame addressed to the existing function units A, B, the relay device  200  relays the received communication setting frame to the existing function units A, B (step S 308 ). 
     Next, the existing function unit A transmits, to the relay device  200 , a communication setting frame that is addressed to the new function unit and that has stored therein: information indicating the content of data that the existing function unit A can transmit; and function unit information of the existing function unit A (step S 310 ). 
     Next, when the relay device  200  has received, from the existing function unit A, the communication setting frame addressed to the new function unit, the relay device  200  acquires the function unit information from the received communication setting frame (step S 312 ). 
     Next, the relay device  200  relays the communication setting frame received from the existing function unit A, to the new function unit (step S 314 ). 
     Next, the existing function unit B transmits, to the relay device  200 , a communication setting frame that is addressed to the new function unit and that has stored therein: information indicating the content of data that the existing function unit B can transmit; and function unit information of the existing function unit B (step S 316 ). 
     Next, when the relay device  200  has received, from the existing function unit B, the communication setting frame addressed to the new function unit, the relay device  200  acquires the function unit information from the received communication setting frame (step S 318 ). 
     Next, the relay device  200  relays the communication setting frame received from the existing function unit B, to the new function unit (step S 320 ). 
     Next, on the basis of each piece of the acquired function unit information, the relay device  200  generates configuration information of a new network (step S 322 ). 
     Next, on the basis of the generated configuration information, the relay device  200  notifies the new function unit and the existing function units A, B of setting contents (step S 324 ). 
     Next, the new function unit performs various setting changes in accordance with the setting content notified of from the relay device  200  (step S 326 ). 
     The existing function units A, B perform various setting changes in accordance with the setting contents notified of from the relay device  200  (step S 328 ). 
     Next, the new function unit and the existing function units A, B in the new network perform communication with each other in accordance with the setting contents after having been changed (step S 330 ). 
       FIG. 14  shows another example of the sequence of the construction process of a new network in the vehicle communication system according to the embodiment of the present disclosure.  FIG. 14  shows a sequence of a construction process of a new network in which new function units A, B being publish function units can transmit data to an existing function unit being a subscribe function unit. 
     With reference to  FIG. 14 , first, the new function unit A that is newly added to the network  12  transmits connection request information to the relay device  200  (step S 402 ). 
     Next, the relay device  200  receives connection request information from the new function unit A to detect the new function unit A, and performs an authentication process regarding the new function unit A (step S 404 ). 
     Next, the new function unit B that is newly added to the network  12  transmits connection request information to the relay device  200  (step S 406 ). 
     Next, the relay device  200  receives the connection request information from the new function unit B to detect the new function unit B, and performs an authentication process regarding the new function unit B (step S 408 ). 
     Next, the new function unit A transmits, to the relay device  200 , a communication setting frame that is addressed to an existing function unit and that has stored therein: information indicating the content of data that the new function unit A can transmit; and function unit information of the new function unit A (step S 410 ). 
     Next, when the relay device  200  has received, from the new function unit A, the communication setting frame addressed to the existing function unit, the relay device  200  acquires the function unit information from the received communication setting frame (step S 412 ). 
     Next, the relay device  200  relays the communication setting frame received from the new function unit A, to the existing function unit (step S 414 ). 
     Next, the existing function unit transmits, to the relay device  200 , a communication setting frame that is addressed to the new function unit A and that has stored therein: the content of data that the existing function unit should receive; and function unit information of the existing function unit (step S 416 ). 
     Next, the relay device  200  relays the communication setting frame received from the existing function unit, to the new function unit A (step S 418 ). 
     Next, the new function unit B transmits, to the relay device  200 , a communication setting frame that is addressed to the existing function unit and that has stored therein: information indicating the content of data that the new function unit B can transmit; and function unit information of the new function unit B (step S 420 ). 
     Next, when the relay device  200  has received, from the new function unit B, the communication setting frame addressed to the existing function unit, the relay device  200  acquires the function unit information from the received communication setting frame (step S 422 ). 
     Next, the relay device  200  relays the communication setting frame received from the new function unit B, to the existing function unit (step S 424 ). 
     Next, the existing function unit transmits, to the relay device  200 , a communication setting frame that is addressed to the new function unit B and that has stored therein: the content of data that the existing function unit should receive; and function unit information of the existing function unit (step S 426 ). 
     Next, the relay device  200  relays the communication setting frame received from the existing function unit, to the new function unit B (step S 428 ). 
     Next, on the basis of each piece of the acquired function unit information, the relay device  200  generates configuration information of a new network (step S 430 ). 
     Next, on the basis of the generated configuration information, the relay device  200  notifies the new function units A, B and the existing function unit of setting contents (step S 432 ). 
     Next, the new function units A, B perform various setting changes in accordance with the setting contents notified of from the relay device  200  (step S 434 ). 
     The existing function unit performs various setting changes in accordance with the setting content notified of from the relay device  200  (step S 436 ). 
     Next, the new function units A, B and the existing function unit in the new network perform communication with each other in accordance with the setting contents after having been changed (step S 438 ). 
     In the relay device  200  according to the embodiment of the present disclosure, when an in-vehicle ECU  111  or an external device has been added to the network  12 , the detection unit  230  detects an application  100  included in the in-vehicle ECU  111  or the external device as a new function unit. However, the present disclosure is not limited thereto. The detection unit  230  may be configured to detect, as a new function unit, an in-vehicle ECU  111  or an external device that is added to the network  12  and that does not have installed therein an application  100 . 
     In the relay device  200  according to the embodiment of the present disclosure, the generation unit  250  outputs generated configuration information to the notification unit  260 , and on the basis of the configuration information received from the generation unit  250 , the notification unit  260  notifies a function unit for which setting change is necessary, of the setting content. However, the present disclosure is not limited thereto. The generation unit  250  may be configured to generate configuration information of a new network, for example, in which setting change in a function unit is not necessary. In this case, the relay device  200  may be configured not to be provided with the notification unit  260 . 
     In the vehicle communication system  300  according to the embodiment of the present disclosure, the function unit information is information that is not to be processed in a function unit that should receive a communication setting frame. However, the present disclosure is not limited thereto. The function unit information may be information that is to be processed in a function unit that should receive a communication setting frame. 
     In the vehicle communication system  300  according to the embodiment of the present disclosure, the function unit information is information that is to be used in generation of configuration information of a new network. However, the present disclosure is not limited thereto. The function unit information may be used in any process other than generation of configuration information of a new network. 
     In the relay device  200  according to the embodiment of the present disclosure, the generation unit  250  generates configuration information of a new network on the basis of function unit information received from the acquisition unit  240 . However, the present disclosure is not limited thereto. The relay device  200  may be configured not to be provided with the generation unit  250 . Alternatively, the relay device  200  may be provided with, instead of the generation unit  250 , a configuration information acquisition unit that acquires, from outside, configuration information of a new network generated on the basis of function unit information acquired by the acquisition unit  240 . 
     Meanwhile, a technology that allows easy acquisition of information of function units in a new network when a new function unit has been added to a network, is desired. 
     For example, when a function unit is newly added to a 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. 
     An example of the network configuration and restriction of a lower order layer is restriction of the communication band of the physical layer. In particular, in the case of a network for which reduced cost is required, e.g., a network that includes in-vehicle function units such as in-vehicle ECUs, it is sometimes difficult, due to restriction of the communication band as described above, to add a new function unit to the network while maintaining stable operation in the network. 
     Therefore, in order to flexibly construct a network having a new configuration while maintaining stable operation in the network, a technology that allows easy acquisition of information of function units in the new network, is desired. 
     In this regard, the relay device  200  according to the embodiment of the present disclosure is installed in the vehicle  1 . In the relay device  200 , the detection unit  230  detects a new function unit being a function unit that is newly added to the network  12  including an existing function unit being one or a plurality of function units. The relay unit  220  relays a frame between function units. The acquisition unit  240  acquires, from a frame, relayed by the relay unit  220 , between the new function unit detected by the detection unit  230  and the existing function unit, function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer, the function unit information being of at least one of the new function unit and the existing function unit. 
     Thus, with this configuration in which the function unit information is acquired from the frame between function units, the function unit information can be acquired from the frame that should be relayed between the new function unit and the existing function unit in order to establish communication connection between the new function unit and the existing function unit, for example. Therefore, it is possible to acquire the function unit information without sending and receiving a frame for acquiring the function unit information between function units. 
     Therefore, in the relay device  200  according to the embodiment of the present disclosure, information of a network to which a new function unit has been added can be easily acquired. 
     In the relay device  200  according to the embodiment of the present disclosure, the function unit information is information that is to be used in generation of configuration information of a new network being the network  12  that further includes the new function unit. 
     With this configuration, it is possible to construct a new network in consideration of the network configuration and restriction of a layer of a lower order than the application layer, for example. Accordingly, for example, occurrence of delay in high importance communication due to addition of a new function unit to the network can be suppressed. 
     In the relay device  200  according to the embodiment of the present disclosure, the acquisition unit  240  acquires the function unit information from the frame transmitted by the new function unit and relayed to the existing function unit. 
     With this configuration, for example, the function unit information can be acquired from the frame transmitted by the new function unit that should transmit data to the existing function unit after establishment of communication connection. 
     In the relay device  200  according to the embodiment of the present disclosure, the acquisition unit  240  acquires the function unit information from the frame transmitted by the existing function unit and relayed to the new function unit. 
     With this configuration, for example, the function unit information can be acquired from the frame transmitted by the existing function unit that should transmit data to the new function unit after establishment of communication connection. 
     In the relay device  200  according to the embodiment of the present disclosure, without changing transmission destination information and transmission source information that are included in the frame received from the function unit, the relay unit  220  relays the frame to another function unit. The acquisition unit  240  acquires the function unit information from the frame relayed by the relay unit  220 . 
     With this configuration, in the relay device  200  that performs snooping on the frame between function units, the function unit information can be easily acquired. 
     In the relay device  200  according to the embodiment of the present disclosure, the relay unit  220  changes at least one of transmission destination information and transmission source information that are included in the frame received from the function unit, and relays the frame after having been changed, to another function unit. The acquisition unit  240  acquires the function unit information from the frame relayed by the relay unit  220 . 
     With this configuration, in the relay device  200  functioning as a proxy server, the function unit information can be easily acquired. 
     In the relay device  200  according to the embodiment of the present disclosure, the generation unit  250  generates configuration information of a new network being the network that further includes the new function unit, on the basis of the function unit information acquired by the acquisition unit  240 . 
     With this configuration, it is possible to construct a new network in consideration of the network configuration and restriction of a layer of a lower order than the application layer, by using the function unit information. Accordingly, for example, occurrence of delay in high importance communication due to addition of a new function unit to the network can be suppressed. 
     In the relay device  200  according to the embodiment of the present disclosure, the function unit information is information that is not to be processed in a function unit that should receive the frame. 
     With this configuration, the function unit information can be acquired from the frame without increasing the processing load in the function unit that should receive the frame. 
     In the relay device  200  according to the embodiment of the present disclosure, the detection unit  230 : detects, as the new function unit, at least one of an application  100  included in an in-vehicle ECU  111  that is newly added to the network  12 , an application  100  that is newly installed into an in-vehicle ECU  111  in the network  12 , and an application  100  included in the external device  113  that is newly added, outside the vehicle  1 , to the network  12 ; performs an authentication process regarding the new function unit detected; and notifies the new function unit of a result of the authentication process. 
     With this configuration, diverse new function units can be detected, and a new network  12  can be constructed. 
     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 of a network to which a new function unit has been added can be easily acquired. 
     In the vehicle communication system  300  according to the embodiment of the present disclosure, existing function units form the network  12 . A new function unit is newly added to the network  12 . The relay device  200  installed in the vehicle  1  detects addition of the new function unit to the network  12 . The new function unit or an existing function unit transmits a frame that is addressed to another function unit and that has stored therein function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer. The relay device  200  acquires the function unit information from the frame transmitted by the new function unit or the existing function unit. 
     Thus, with this configuration in which the function unit information is acquired from the frame transmitted by the new function unit or the existing function unit, the function unit information can be acquired from the frame that should be relayed between the new function unit and the existing function unit in order to establish communication connection between the new function unit and the existing function unit, for example. Therefore, it is possible to acquire the function unit information without sending and receiving a frame for acquiring the function unit information between function units. 
     Therefore, in the vehicle communication system  300  according to the embodiment of the present disclosure, information of a network to which a new function unit has been added can be easily acquired. 
     A communication method according to the embodiment of the present disclosure is a communication method performed in the relay device  200  that is installed in the vehicle  1  and that relays a frame between function units. In this communication method, first, the relay device  200  detects a new function unit being a function unit that is newly added to the network  12  including an existing function unit being one or a plurality of function units. Next, the relay device  200  acquires, from the frame that should be relayed between the new function unit detected and the existing function unit, function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer, the function unit information being of at least one of the new function unit and the existing function unit. 
     Thus, with this method in which the function unit information is acquired from the frame that should be relayed between the new function unit and the existing function unit, the function unit information can be acquired from the frame that should be relayed between the new function unit and the existing function unit in order to establish communication connection between the new function unit and the existing function unit, for example. Therefore, it is possible to acquire the function unit information without sending and receiving a frame for acquiring the function unit information between function units. 
     Therefore, in the communication method according to the embodiment of the present disclosure, information of a network to which a new function unit has been added can be easily acquired. 
     A communication method according to the embodiment of the present disclosure is a communication method performed in the vehicle communication system  300 . The vehicle communication system  300  includes: the relay device  200  installed in the vehicle  1 ; one or a plurality of existing function units forming the network  12 ; and a new function unit that is newly added to the network  12 . In this communication method, first, the relay device  200  detects addition of the new function unit to the network  12 . Next, the new function unit or an existing function unit transmits a frame that is addressed to another function unit and that has stored therein function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer. Next, the relay device  200  acquires function unit information from the frame transmitted by the new function unit or the existing function unit. 
     With this method in which the function unit information is acquired from the frame transmitted by the new function unit or the existing function unit, the function unit information can be acquired from the frame that should be relayed between the new function unit and the existing function unit in order to establish communication connection between the new function unit and the existing function unit, for example. Therefore, it is possible to acquire the function unit information without sending and receiving a frame for acquiring the function unit information between function units. 
     Therefore, in the communication method according to the embodiment of the present disclosure, information of a network to which a new function unit has been added can be easily acquired. 
     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 comprising: 
     a detection unit configured to detect a new function unit being a function unit that is newly added to a network including an existing function unit being one or a plurality of function units; 
     a relay unit configured to relay a frame between the function units; 
     an acquisition unit configured to acquire, from the frame, relayed by relay unit, between the new function unit detected by the detection unit and the existing function unit, function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer, the function unit information being of at least one of the new function unit and the existing function unit; and 
     a generation unit configured to generate configuration information of a new network being the network that further includes the new function unit, on the basis of the function unit information acquired by the acquisition unit, wherein 
     the acquisition unit acquires the function unit information from the frame transmitted by a function unit, out of the new function unit and the existing function unit, that performs data transmission in the new network. 
     [Additional Note 2] 
     A vehicle communication system comprising: 
     a relay device; 
     an existing function unit being one or a plurality of function units forming a network; and 
     a new function unit being a function unit that is newly added to the network, wherein 
     the relay device detects addition of the new function unit to the network, 
     a function unit, out of the new function unit or the existing function unit, that performs data transmission in a new network being the network that further includes the new function unit transmits a frame that is addressed to another function unit and that has stored therein function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer, and 
     the relay device acquires the function unit information from the frame transmitted by the new function unit or the existing function unit. 
     [Additional Note 3] 
     A relay device including a processor, 
     the processor realizing:
         a detection unit configured to detect a new ECU being an in-vehicle ECU that is newly added to a network including an existing ECU being one or a plurality of in-vehicle ECUs;   a relay unit configured to relay a frame between the in-vehicle ECUs;   an acquisition unit configured to acquire, from the frame, relayed by the relay unit, between the new ECU detected by the detection unit and the existing ECU, function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer, the function unit information being of at least one of the new ECU and the existing ECU; and   a generation unit configured to generate configuration information of a new network being the network that further includes the new ECU, on the basis of the function unit information acquired by the acquisition unit, wherein       

     the acquisition unit acquires the function unit information from the frame transmitted by an in-vehicle ECU, out of the new ECU and the existing ECU, that performs data transmission in the new network. 
     [Additional Note 4] 
     A vehicle communication system comprising: 
     a relay device; 
     an existing ECU being one or a plurality of in-vehicle ECUs forming a network; and 
     a new ECU being an in-vehicle ECU that is newly added to the network, wherein 
     a CPU in the relay device detects addition of the new ECU to the network, 
     an in-vehicle ECU, out of the new ECU or the existing ECU, that performs data transmission in a new network being the network that further includes the new ECU transmits a frame that is addressed to another in-vehicle ECU and that has stored therein function unit information that includes information regarding a network configuration of a layer of a lower order than an application layer, and 
     the CPU in the relay device acquires the function unit information from the frame transmitted by the new ECU or the existing ECU. 
     REFERENCE SIGNS LIST 
       1  vehicle 
       10  VLAN 
       11  Ethernet cable 
       12  network 
       20  VLAN 
       30  VLAN 
       100  application 
       111  in-vehicle ECU 
       113  external device 
       120  communication port 
       161  wireless base station device 
       170  external network 
       180  server 
       200  relay device 
       220  relay unit 
       230  detection unit 
       240  acquisition unit 
       250  generation unit 
       260  notification unit 
       270  storage unit 
       300  vehicle communication system 
       400  communication system