Switching hub and communication network

The present invention relates to a switching hub that constitutes a hierarchical communication network mounted on a vehicle.

Layer 2 switching hubs that may be used as network switches (hereinafter simply referred to as switches) in vehicle Ethernet (registered trademark) communication networks do not have MAC addresses and also have IP addresses. It is common not to have. Therefore, it is difficult to individually identify the switching hub itself. If each switching hub cannot be identified individually, for example, the master device cannot individually instruct each switching hub to rewrite the config setting or read out the failure information. As a solution to such a problem, for example, there is a method of using a layer 3 switch, that is, a method of giving the switch a static IP address, but the part number management of the switch becomes complicated and the cost increases. Also, the layer 3 switch itself is more expensive than the layer 2 switch (layer 2 switching hub).

Further, for example, Patent Document 1 describes a technique for distributing frame data by a plurality of switch nodes.

<p num="0004"><patcit num="1"><text>Japanese Unexamined Patent Publication No. 2011-249979</text></patcit></p>

<p num="0005"> In the technique of Patent Document 1, it is not possible to dynamically have an identifier for a switching hub that does not have an identifier. Therefore, it is not possible to give individual instructions to the switching hub.</p><p num="0006"> Therefore, an object of the present invention is to enable a switching hub that constitutes a hierarchical communication network mounted on a vehicle to dynamically have an ID number as an identifier.</p>

<p num="0007"> The switching hub of the first invention is a switching hub that constitutes a hierarchical communication network mounted on a vehicle. The switching hub includes a memory for storing an ID number as an identifier of the switching hub, a first means, and a second means.</p><p num="0008"> The first means stores the ID number received from a specific port of the switching hub in the memory as an identifier of the switching hub. The second means is to transmit from the port of the switching hub by combining the port number of the port and the received ID number of each of the ports other than the specific port according to a predetermined rule. Generate an ID number to be used. Then, the generated ID number is transmitted from the port of the port number used to generate the ID number.</p><p num="0009"> When constructing a hierarchical communication network using this switching hub, ports other than the specific port in the switching hub of the upper layer may be connected to the specific port in the switching hub of the lower layer. By connecting in this way, different ID numbers can be stored in the memory of each switching hub by inputting the start value of the ID number to the specific port in the switching hub of the uppermost layer.</p><p num="0010"> Therefore, each of the switching hubs constituting the communication network can dynamically have an ID number as an identifier. Further, for this reason, the master device in the communication network can individually instruct each switching hub to execute a predetermined process by using the ID number stored in each switching hub.</p><p num="0011"> The reference numerals in parentheses described in the claims indicate, as one embodiment, the correspondence with the specific means described in the embodiments described later, and limit the technical scope of the present invention. is not it.</p>

<figref num="1">It is a block diagram which shows the structure of the communication network of embodiment.</figref><figref num="2">It is a ladder chart which shows the operation content of each device in a communication network.</figref><figref num="3">It is explanatory drawing which shows the structure of an Ethernet frame.</figref><figref num="4">It is explanatory drawing of ID table.</figref>

Hereinafter, the communication network of the embodiment to which the present invention is applied will be described. [Structure of the present embodiment] The communication network 1 of the embodiment shown in FIG. 1 is a hierarchical Ethernet network mounted on a vehicle such as a passenger car, and constitutes a communication system in the vehicle.

As shown in FIG. 1, the communication network 1 includes a plurality of switching hubs (hereinafter referred to as switches) 12 to 17 and a plurality of electronic control devices (hereinafter referred to as ECUs) 20 to 27. ECU is an abbreviation for "Electronic Control Unit".

Each ECU 20 to 27 has a function of a microcomputer (not shown) having a CPU, ROM, RAM, and the like. The ECU 20 of the ECUs 20 to 27 is the master ECU in the communication network 1. And the master ECU 20 is equipped with a switch 11. The master ECU 20 is, for example, a central gateway.

Switches 11 to 17 are layer 2 switches among Ethernet switches, and perform communication using the Ethernet standard. Therefore, the switches 11 to 17 identify the destination device by using the MAC address included in the data, and relay the data to the communication line to which the destination device is connected. Further, each of the switches 11 to 17 includes a memory 30 for storing an ID number as an identifier of the switch, and a processing unit (not shown) composed of an IC, a microcomputer, or the like that controls the operation of the switch. The memory 30 is, for example, volatile RAM, but may be a rewritable non-volatile memory.

In the communication network 1, all the devices (switches and ECUs in this example) constituting the communication network 1 exchange data using the Ethernet standard. Then, each device constitutes a hierarchical Ethernet network by connecting the master ECU 20 as a device of the highest layer (first layer) in a tree shape.

That is, the port P1 of the switch 11 provided in the master ECU 20 is connected to the port P0 of the switch 12 and 4 via the communication line 41. Further, the port P2 of the switch 11 is connected to the port P0 of the switch 13 via the communication line 42, and the port P3 of the switch 11 is connected to the port P0 of the switch 14 via the communication line 43. There is.

Ports P1 and P2 of switch 12 are connected to ECUs 21 and 22 via communication lines 44 and 45, respectively, and ports P1 and P2 of switch 14 are connected to ECUs 24 and 25 via communication lines 48 and 49, respectively. Has been done. Further, the port P1 of the switch 13 is connected to the ECU 23 via the communication line 46, and the port P2 of the switch 13 is connected to the port P0 of the switch 15 via the communication line 47.

The port P1 of the switch 15 is connected to the port P0 of the switch 16 via the communication line 50, and the port P2 of the switch 15 is connected to the port P0 of the switch 17 via the communication line 51. Then, the port P1 of the switch 16 is connected to the ECU 26 via the communication line 52, and the port P1 of the switch 17 is connected to the ECU 27 via the communication line 53.

In this way, switches 12 to 14 are devices in the second layer, switches 15 and ECUs 21 to 25 are devices in the third layer, and switches 16 and 17 are devices in the fourth layer. ECUs 26 and 27 are the 5th layer devices.

[Processing of the present embodiment] In the communication network 1 having such a configuration, each switch 11 to 17 dynamically stores an ID number as its own identifier. The processing procedure at this time will be described with reference to FIG. In the description of FIG. 2, the operations of the switches 11 and 12 will be described, but the operations of the other switches 13 to 17 are the same as the operations described for the switches 11 and 12. The operation of ECUs 21 and 22 will also be described, but the operations of other ECUs 23 to 27 are the same as the operations described for ECUs 21 and 22.

For example, when a start condition such as turning on the ignition switch of the vehicle is satisfied, power is supplied to each device of the communication network 1 and each device is started. Then, when the master ECU 20 is started by supplying power, it transmits an Ethernet frame (hereinafter, also referred to as an ID assignment frame) including an ID assignment instruction and an ID number to the port P0 of the switch 11 in the master ECU 20 (S100). ).

Here, an Ethernet frame is composed of a preamble, a destination MAC address, a source MAC address, a type, data, and an FCS (Frame Check Sequence), for example, as shown in FIG. Among them, in the data area, an ID assignment indicator area indicating that this Ethernet frame is an ID assignment frame for ID assignment and an ID area which is a storage area of the ID number assigned to the switch are provided. ing. For example, the ID assignment indicator is 1 bit, and the fact that this ID assignment indicator is 1 corresponds to the ID assignment instruction. Therefore, the Ethernet frame whose ID assignment indicator is 1 is the ID assignment frame. Also, for example, 2 bytes are prepared as the ID area.

Then, in the master ECU 20, "0" is set as the start value of the ID number as the ID number (specifically, the ID number stored in the ID area) in the ID assignment frame input to the port P0 of the switch 11. To. In the present embodiment, the ID number is a decimal number.

The switch 11 checks the ID assignment indicator in the Ethernet frame received from the port P0 (S110), and if the ID assignment indicator is 1, performs the first operation and the second operation.

&lt;First operation&gt; The switch 11 stores the ID number included in the Ethernet frame (in this case, the ID assignment frame) received from the port P0 (corresponding to a specific port) in its own memory 30 as its own ID number (S120). ..

&lt;Second operation&gt; The switch 11 sets the port number and the received ID number of each of the ports P1 to P3 other than the port P0 among its own ports Pn (n is an integer of 0 or more) according to a predetermined rule. By combining, an ID number to be sent from that port is generated (S130). Specifically, n, which is the port number of port Pn, is a decimal number like the ID number. Then, for example, the above rule generates a decimal ID number represented by arranging the two numerical values, with the port number of the target port as the lower digit number and the received ID number as the upper digit number. Is the rule. Further, the switch 11 transmits each ID number generated for each port P1 to P3 from each port P1 to P3 of the port number used for generating the ID number (S140). Specifically, an ID assignment frame including the generated ID number is transmitted from each port P1 to P3 of the port number used to generate the ID number.

The ID assignment frame transmitted from port P1 of switch 11 is input to port P0 of switch 12. Like the switch 11, the switch 12 also checks the ID assignment indicator in the Ethernet frame received from the port P0 (S210), and if the ID assignment indicator is 1, the first operation and the second operation described above are performed. Do the action.

Therefore, the switch 12 also stores the ID number included in the ID assignment frame received from the port P0 in its own memory 30 as its own ID number (S220). Further, the switch 12 also has its own ports P0 to P2, and for each port P1 and P2 other than the port P0, the port number of the port and the received ID number are combined according to the above rule, so that the switch 12 can be used from that port. Generate an ID number to send (S230). Then, each ID number generated for each port P1 and P2 (specifically, an ID assignment frame including each generated ID number) is transferred from each port P1 and P2 of the port number used to generate the ID number. Send (S240).

The ID assignment frame transmitted from the port P1 of the switch 12 is received by the ECU 21, and the ID assignment frame transmitted from the port P2 of the switch 12 is received by the ECU 22.

Each of ECUs 21 and 22 confirms the ID assignment indicator in the received Ethernet frame. Then, in this case, since the ID assignment indicator is 1, the ECUs 21 and 22 determine that the received Ethernet frame is an ID assignment frame and discard the received Ethernet frame (S310).

By the above processing, as shown in FIG. 1, "0" is stored as the ID number in the memory 30 of the switch 11. Then, in the switch 11, the port P1 transmits an ID assignment frame containing "1" as the ID number, the port P2 transmits an ID assignment frame containing "2" as the ID number, and the port P3 transmits an ID assignment frame. , An ID assignment frame containing "3" as the ID number is transmitted. In FIG. 1, the numerical value shown in the downward arrow indicates the ID number in the ID assignment frame.

Therefore, "1" is stored as the ID number in the memory 30 of the switch 12, "2" is stored as the ID number in the memory 30 of the switch 13, and "2" is stored in the memory 30 of the switch 14 as the ID number. "3" is memorized.

Then, in the switch 12, the port P1 transmits an ID assignment frame including "11" as the ID number, and the port P2 transmits an ID assignment frame including "12" as the ID number.

Further, in the switch 13, the port P1 transmits an ID assignment frame including "21" as the ID number, and the port P2 transmits an ID assignment frame including "22" as the ID number.

Further, in the switch 14, the port P1 transmits an ID assignment frame including "31" as the ID number, and the port P2 transmits an ID assignment frame including "32" as the ID number.

Since the ID assignment frame transmitted from the port P2 of the switch 13 is input to the port P0 of the switch 15, "22" is stored as the ID number in the memory 30 of the switch 15.

Then, in the switch 15, the port P1 transmits an ID assignment frame including "221" as the ID number, and the port P2 transmits an ID assignment frame including "222" as the ID number.

Therefore, "221" is stored as the ID number in the memory 30 of the switch 16, and "222" is stored as the ID number in the memory 30 of the switch 17. Then, in the switch 16, the ID assignment frame including "2211" as the ID number is transmitted from the port P1. Further, in the switch 17, an ID assignment frame including "2221" as an ID number is transmitted from the port P1.

In addition, each of ECUs 21 to 27 receives an ID assignment frame from a switch arranged one level higher than itself, but since it is an ID assignment frame, it is discarded.

[Effect of this embodiment] According to the above switches 11 to 17, each switch 11 to 17 dynamically has a unique ID number as an identifier in the state where the hierarchical communication network 1 is configured as shown in FIG. 1 ( In other words, you can give an ID number). The technique of the present embodiment adds a function for identifying a frame (S110 or S210) and a function for performing the above-mentioned first and second operations (S120 to S140 or S220 to S240) to the layer 2 switch. All you have to do is do it. Therefore, the layer 3 level IP routing function is unnecessary.

Further, since the switches 11 to 17 generate the ID number transmitted from their own port according to the above-mentioned rule, there is an advantage that the ID number assigned to each switch 11 to 17 is intuitively easy to understand.

Then, according to the present embodiment, any device in the communication network 1 individually instructs each switch 11 to 17 to execute a predetermined process by using the ID number stored in each of the switches 11 to 17. You will be able to do it. As the predetermined processing instructing each switch 11 to 17, for example, rewriting of the config setting, reading of failure information, shift to power saving control, and the like can be considered. Config is an abbreviation for configuration and indicates all settings related to switch functions. Then, as the config setting, for example, the presence / absence of the auto-negotiation function, the type of error information to be stored, and the enable / disable of the power saving mode can be considered.

[Specific example when instructing each switch to execute processing] Since the in-vehicle environment is static, the ID numbers to be stored by the switches 11 to 17 constituting the communication network 1 by the above-mentioned first and second operations can be logically and correctly estimated in advance. ..

Therefore, for example, the master ECU 20 can store an ID table (see FIG. 4) showing the correspondence between the switches 11 to 17 constituting the communication network 1 and their ID numbers. The master ECU 20 can search the ID numbers of the switches 11 to 17 by referring to the ID table.

Then, when the master ECU 20 causes any of the switches 11 to 17 to execute a desired process, the master ECU 20 may perform the following operations, for example. The master ECU 20 sets the ID number of the switch instructing the execution of the process and the command indicating the content of the process to be executed by the switch in the data area in the Ethernet frame transmitted to all the devices in the communication network 1. By including it, a processing instruction frame is created. Then, the master ECU 20 inputs the created processing instruction frame to port P0 of the switch 11, for example, to transmit the processing instruction frame to all the devices.

On the other hand, each of the switches 11 to 17 may perform the following operations. That is, if each of the switches 11 to 17 includes the above command in the data area in the received Ethernet frame and includes the same ID number as the ID number stored in its own memory 30, the switches 11 to 17 include the above command. The process indicated by the received command may be executed.

[Other Embodiment 1] The rule for each switch 11 to 17 to generate an ID number transmitted from a port is, for example, "a binary number indicating a predetermined number of bits (for example, 4 bits) indicating a port number, and a binary number indicating a received ID number. A rule such as "add as a bit string below the data string" may be used.

[Other Embodiment 2] The master ECU 20 may be a device outside the vehicle (for example, a tool for performing failure diagnosis). In that case, in FIG. 1, devices in a lower layer (that is, the second and subsequent layers) than the master ECU 20 constitute an in-vehicle communication network.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various forms can be adopted. Further, the above-mentioned numerical values are also examples, and other values may be used. For example, the functions of one component in the above embodiment may be distributed as a plurality of components, or the functions of the plurality of components may be integrated into one component. Further, at least a part of the configuration of the above embodiment may be replaced with a known configuration having the same function. Further, a part of the configuration of the above embodiment may be omitted. It should be noted that all aspects included in the technical idea specified by the wording described in the claims are embodiments of the present invention. In addition to the above-mentioned switches 11 to 17 and communication network 1, for example, a program for operating a computer as switches 11 to 17, a medium on which this program is recorded, a method of assigning an ID number to a switching hub, and the like are used in various forms. The present invention can also be realized.

1 ... Communication network, 11 ~ 17 ... Switching hub (switch), 30 ... Memory