Message Processor

Abstract

A message processor (61, 62) is described. The message processor is configured to generate a packet (14), such as a layer 2 packet or a layer 3 packet, having a predetermined data format including a header (24; FIG. 4) and payload data (25; FIG. 4) in response to receiving a data packet (131, 132) formatted according to a given communication protocol (e.g., CAN or Ethernet) and including packet guide data (22; FIG. 4) and payload data (23; FIG. 4). The header includes an address generated according to the packet guide data, and wherein the payload includes the data packet. The packet (14) having the predetermined data format may be an IEEE 1722 frame.

Description

[0001] This application is a divisional application of an invention with an application date of February 18, 2016, application number 201680080906.6 (international application number PCT / EP2016 / 053459) and name “Message Processor”. Technical Field

[0002] The present invention relates to a message handler and a control unit, the control unit comprising at least two message handlers and a message forwarder configured to switch or route data packets between the message handlers. Background Art

[0003] A gateway allows information to be exchanged between different network interfaces. The network interfaces may use the same or different OSI physical layer ("layer 1"), data link ("layer 2"), and / or network layer ("layer 3") protocols such as Ethernet, Controller Area Network (CAN), FlexRay, and Media Oriented Systems Transport (MOST). Examples of gateways include Ethernet switches, Digital Subscriber Line Access Multiplexers (DSLAMs), and Fieldbus gateways.

[0004] Layer 2 gateways within the same protocol (e.g. Ethernet 10 / 100 / 1000 switches and CAN / CAN gateways) tend to be simple because the frames in the data link layer are the same, although the data rates may change. Layer 2 gateways across protocols (e.g. CAN / CAN-FD gateways) can provide re-framing without changing the packet (or "package") at the network layer. Layer 3 gateways (e.g. IPv4 / IPv6 gateways or CAN / Ethernet gateways) can restructure packets for different addressing and flow control requirements. Layer 4 to Layer 7 gateways (e.g. TCP / UDP gateways and AUTOSAR signal gateways) allow changing between different transport protocols and reassembling information.

[0005] Layer 2 gateways within the same protocol or protocol family are often implemented in hardware, and examples of such gateways include the CAN / CAN gateway in the Renesas RH850 / C1M microcontroller and the CAN / CAN-FD gateway in the Renesas RH850 / D1M microcontroller.

[0006] refer to Figure 1, Layer 3 gateways are usually implemented in software. A microcontroller has a set of network interfaces and software executed by the central processing unit of the microcontroller that can reassemble the packets based on a configuration matrix. Examples of such gateways include USB / UART converters and automotive CAN / LIN / FlexRay gateways. Since communication protocols have different addressing schemes and have different message structures, software provides the flexibility to convert between different protocols.

[0007] Layer 4 to 7 gateways are typically implemented in software. Reassembling data at higher layers often requires significant configurability and flexibility, and while hardware-based solutions are possible, for example in time-critical, conversion-specific cases such as video data, this can really only be accomplished with software-based implementations.

[0008] The framing of network layer packets is usually implemented in hardware and is transparent to the routing mechanism. Examples where packet framing occurs include Ethernet MACs, FlexRay communication controllers, and CAN protocol engines. All protocols tend to have separate, optimized interfaces to exchange information with higher layers.

[0009] Layer 3 gateways within the same protocol suite also tend to be easy to implement in hardware. In cases involving, for example, CAN / CAN-FD conversion and IPv4 / IPv6 conversion, only minimal changes to the packet structure are required.

[0010] Layer 3 gateways involving different protocols are often difficult to implement in hardware because packets need to be reformatted to accommodate different addressing, routing, and flow control schemes. Packet conversion often requires flexible, configurable data manipulation units. This can lead to information gaps because not all frame information is convertible, such as in the case of Ethernet lengths to CAN DLC.

[0011] Addressing scheme conversion requires configurable conversion tables between the two network layers. Flow control scheme conversion usually requires new layer 4 transport protocols or other advanced support.

[0012] Communication systems increasingly include more than one type of bus system interconnected with each other, which makes the forwarding of data more complicated.

[0013] US2014 / 0133350A1 describes a gateway module for connecting at least two subnets, the at least two subnets comprising a first subnet and a second subnet supporting data transmission according to a first communication protocol and a second communication protocol, respectively. The gateway module has a configurable hardware circuit that is suitable for manipulating and forwarding data from the first subnet and to the second subnet, taking into account the first communication protocol and the second communication protocol. However, as the number and type of communication protocols increase, this type of gateway becomes increasingly complex or requires hardware modifications. Therefore, when a new communication interface is introduced, not only must a new interface module be added, but also the gateway module needs to be modified. Summary of the invention

[0014] According to a first aspect of the present invention, there is provided a message processor. The message processor is configured to generate a packet having a predetermined data format including a header and payload data, such as a layer 2 packet or a layer 3 packet, in response to receiving a data packet formatted according to a given communication protocol and including packet guide data and payload data. The header includes an address generated according to the packet guide data, and the payload includes a packet.

[0015] Thus, different message processors for different communication protocols may be provided in the control unit and used to generate packets having a common data format. This helps to facilitate the exchange of data between two or more communication buses and the host processor, and enables hardware-based switches or routers to be used to exchange data between the buses. Thus, the same routing mechanism may be used regardless of the specific communication protocols used, whether they are the same or different protocols.

[0016] The incoming data packet may not include cyclic redundancy check data. The incoming data packet may include a timestamp.

[0017] The packet guidance data may include a message identification or message content identifier (which may be used to identify a multicast destination), or a destination node address. The address may be a stream identifier.

[0018] The message processor may be configured to copy data from a first field in the packet guide data to a corresponding field in the header. The message processor may be configured to add predetermined data to a second field in the header. The predetermined data may be provided by the host processor. The message processor may be configured to add calculated data to the header based on data from the first field and / or to add calculated data to the second field in the header based on data from the second field, to add calculated data to the header.

[0019] The message processor may be configured to, in response to receiving a packet having a predetermined data format including a header and payload data, extract a data packet formatted according to a given communication protocol and including packet guide data and payload data.

[0020] According to a second aspect of the present invention, there is provided a message processor configured to extract a data packet formatted according to a given communication protocol and comprising packet guide data and payload data in response to receiving a packet having a predetermined data format including a header and payload data.

[0021] The packet with the predetermined data format may be an IEEE 1722 frame. The predetermined data format may conform to IEEE 1722. The packet with the predetermined data format may be an AVTP control message. The address may be a stream ID. The packet with the predetermined data format may be a layer 2 frame. The packet with the predetermined data format may be an IP packet, such as an IPv4 or IPv6 packet.

[0022] The given communication protocol may be ISO 11898-1 (or "CAN 2.0"). The given communication protocol may be the Controller Area Network Flexible Data-rate (CAN-FD) protocol. The given communication protocol may be the FlexRay protocol. The given communication protocol may be IEEE 802.3 (i.e., Ethernet). The given communication protocol may be the Media Oriented Systems Transport (MOST) protocol. The given communication protocol may be Ethernet-based. The given communication protocol may be EtherCAT, CC-Link IEField, PROFINET, EtherNet / IP, Modbus TCP, or FL-net.

[0023] According to a third aspect of the present invention, there is provided a network interface module which is implemented in hardware, comprises a protocol engine and a message processor, and is configured to exchange data packets formatted according to a given communication protocol with the protocol engine.

[0024] According to a fourth aspect of the invention there is provided a central processing unit subsystem comprising a central processing unit, a memory and a computer program stored in the memory or other storage, which when executed by the central processing unit causes the central processing unit to execute a message processor.

[0025] According to a fifth aspect of the present invention, there is provided a message forwarder configured to exchange packets having a predetermined data format with a first message processor and a second message processor, the first message processor and the second message processor being used to process messages according to respective first communication protocols and second communication protocols. The message forwarder may be a layer 2 switch and / or a layer 3 router.

[0026] According to a sixth aspect of the present invention, there is provided a control unit, comprising: a first message processor or a network interface module configured to process a data packet formatted according to a first communication protocol; a second message processor or a network interface module configured to process a data packet formatted according to a second communication protocol; and a message forwarder configured to exchange packets having a predetermined data format between the first message processor and the second message processor. The message forwarder may be a layer 2 switch or a layer 3 router.

[0027] The first communication protocol and the second communication protocol may be different. The first communication protocol and the second communication protocol may be the same.

[0028] The control unit may further include a third message configured to process data packets formatted according to a third communication protocol (which may be the same as or different from the first communication protocol and / or the second communication protocol).

[0029] The control unit may further comprise a central processing unit system, wherein the message forwarder is configured to exchange between the central processing unit subsystem and the first message processor and / or the second message processor.

[0030] The control unit may be an integrated circuit, such as a microcontroller or a system on a chip.

[0031] According to a seventh aspect of the present invention, a communication system is provided, comprising at least two sets of buses and at least one control unit according to the second aspect of the present invention connected to the buses. The buses may comprise different types of buses (e.g., CAN, CAN-FD, and Ethernet).

[0032] According to an eighth aspect of the present invention, there is provided a vehicle comprising a communication system.

[0033] The vehicle may be a motor vehicle. The motor vehicle may be a motorcycle, a car (sometimes called a "sedan"), a minibus, a bus, a truck or a lorry. The motor vehicle may be powered by an internal combustion engine and / or one or more electric motors. The vehicle may be a train or a part of a train, such as a locomotive, a railway car or a plurality of units.

[0034] The vehicle may be an aircraft. The communication system may be an Avionics Full Duplex Switched Ethernet (AFDX) system.

[0035] According to a ninth aspect of the present invention, there is provided an industrial system, such as a factory or a machine, comprising a communication system. The factory or the machine may comprise an industrial system for manufacturing or processing.

[0036] According to a tenth aspect of the present invention, there is provided a medical system comprising a communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Reference will now be made to the accompanying drawings Figures 2 to 8 Certain embodiments of the present invention are described by way of example, in which:

[0038] Figure 1 is a schematic block diagram of a communication system in which data can be exchanged between buses by software;

[0039] Figure 2 is a schematic block diagram of a communication system in which data can be exchanged between buses by hardware;

[0040] Figure 3 is a schematic block diagram of a control unit;

[0041] Figure 4 shows the conversion of packets dependent on the communication protocol into packets of a common format;

[0042] Figure 5 The conversion of packets of a generic format into packets dependent on a communication protocol is shown;

[0043] Figure 6 A CAN frame including a CAN-dependent packet is shown;

[0044] Figure 7 AVTP common messages are shown;

[0045] Figure 8 is a schematic diagram of the vehicle communication network and the vehicle; and

[0046] Fig. 9 is a schematic diagram of an industrial communication network and robots. DETAILED DESCRIPTION

[0047] Communication system 1

[0048] Figure 2 A communication system 1 is shown comprising a first part 21 and a second part 22 connected to a first set of buses 31 and a second set of buses 32 for implementing the lowest protocol layers of a first communication protocol and a second communication protocol (eg Controller Area Network (CAN) and Ethernet).

[0049] The first part 21 includes a physical layer module 41, a protocol engine module 51 and a message processor 61. The protocol engine module 51 and the message processor 61 are connected to the network interface module 71 ( Figure 3 ) is implemented in hardware.

[0050] The second part 22 includes a physical layer module 42, a protocol engine module 52 and a message processor 62. The protocol engine module 52 and the message processor 62 are connected to the network interface module 72 ( Figure 3 ) is implemented in hardware.

[0051] The message processors 61, 62 are interconnected by a package or message forwarder 8, which may take the form of a layer 2 switch or a layer 3 router. The message forwarder 8 is preferably implemented in hardware including appropriate hardware logic, hardware registers, etc. The message forwarder 8 does not perform any protocol conversion. The message forwarder 8 is also connected to a higher layer 10 via a unified network stack 9. The unified network stack 9 and the higher layer 10 are implemented in software.

[0052] The physical layer modules 41, 42 pass the input frames 121, 122 to the protocol engines 51, 52, which may remove frame components, such as a frame check sequence (FCS), and generate packets 131, 132. The protocol engines 51, 52 may add information to the packets 131, 132, such as a timestamp.

[0053] The protocol engines 51, 52 pass the packets 131, 132 to the message processors 61, 62, which generate the common format packets 14. As will be explained in more detail later, the message processors 61, 62 may pass the common format packets 14 to the message forwarders 8 to switch or route the common format packets 14 to another message processor 61, 62 and / or the unified network stack 9. Thus, packets may be forwarded not only between the message processors 61, 62, but also to a higher layer 10.

[0054] If there are more than two message processors 61, 62, the message forwarder 8 can switch or route packets to more than one message processor 61, 62, and to higher layers 10, if necessary. The message forwarder 8 can unicast or multicast messages.

[0055] Also refer to Figure 3 , the physical layer modules 41, 42 take the form of PHY transceivers 41, 42. The protocol layers 51, 52, message processors 61, 62, message forwarders 8, unified stack 9 and higher layers 10 are implemented in the control unit 16 in the form of a microcontroller or system on chip. The control unit 16 includes a network interface module 71, 72 (or "communication controller") that provides the protocol engine 51, 52 and the message processors 61, 62. The control unit 16 includes a central processing unit subsystem 17, which includes at least one central processing unit (CPU) 18, a memory 19 and an on-chip interconnect (not shown). The physical layer modules 41, 42 can also be implemented in a microcontroller or a system on chip.

[0056] The CPU 18 can configure the network interface modules 71, 72 and the message repeater 8. The CPU 18 can also bypass the message repeater 8 and access the message processor 61, 62 to be able to read, write and process frames more directly. Therefore, the message forwarding mechanism does not need to be used for all frames. For example, message forwarding can be used to automatically route frames for certain predetermined types of frames. Although the message repeater 8 can be bypassed, the CPU 18 can still use a universal format, although it can also process data in a specific media format, such as CAN.

[0057] The CPU 18 may run a software based message processor 20. This may allow the CPU 18 to prepare a common format message 14 which may then be sent directly or through a message router 8 to one or more message processors 61, 62.

[0058] Message Processor 61 , 62

[0059] As described above, the message processors 61 , 62 receive data packets 131 , 132 from the corresponding protocol engines 51 , 52 (eg, CAN protocol engines) and generate the common format packets 14 .

[0060] Also refer to Figure 4 , each data packet 131 , 132 includes an address 22 and a payload 23 depending on the protocol.

[0061] The format of address 22 and how address 22 is used depends on the communication protocol. For example, Ethernet uses a 48-bit media access control (MAC) address to identify the target node for unicasting or multicasting a packet. CAN uses an 11-bit or 29-bit message identifier to identify the message content for multicasting a message. FlexRay uses a temporary relationship to identify the message content for multicasting a message.

[0062] Priority control may be included in the address, in the payload 23, or signaled in other ways. For example, in Ethernet, priority information is included in the payload, while in CAN, message priority is included in the message identifier. In FlexRay, message priority is based on repetition in a predefined period.

[0063] The message processor 61, 62 extracts the protocol-dependent address 22 from the data packet 131, 132 and prepares a general format header 24 and a payload 25. The general format header 24 includes a general format address 26.

[0064] The message processors 61, 62 map the protocol-dependent addresses 22 to the universal format addresses 26. Preferably, the addresses and message identifiers are separated into different fields. This can help simplify the routing of the universal format packets 14. The message processors 61, 62 encapsulate the data packets 131, 132 received from the protocol engines 51, 52 into the payload 25 of the universal format message 14. Therefore, the universal format message 14 can carry information for all supported data link layers, such as the CAN message ID as well as the universal format address. If the universal format message 14 uses a layer 2 or layer 3 protocol that does not allow tunneling of all fields (such as the baud rate bits of CAN), resulting in lost information, the message processors 61, 62 can be configured to fill in the missing information, for example, the message processors 61, 62 can be configured by software running on the CPU 18.

[0065] Also refer to Figure 5 , when the message processor 61,62 receives the common format packet 14 from the message forwarder 10, the message processor 61,62 discards the header 26 and extracts the data packet 131,132 from the payload 25. The message processor 71,72 then forwards the packet 131,132 to the protocol engine 51,52.

[0066] As previously mentioned, the message forwarder 8 may forward the common format packet 14 to more than one destination. One or more of the destinations may include more than one message processor 61, 62. One or more of the destinations may include a CPU 18.

[0067] The universal format package 14 provides a universal addressing format that allows the control unit 16 ( Figure 3 ) external to the target node (not shown) and the identification of the target service (not shown) running on the CPU 18. The universal addressing format preferably also provides a quality of service (QoS) level. The universal addressing format provides a minimum set of information to allow switching or routing.

[0068] The generic format package 14 provides a container that allows a communication protocol, such as Ethernet, CAN or FlexRay, to map the messages of the communication protocol back to the protocol specific message format of the communication protocol.

[0069] The generic format packet 14 may be any suitable type of layer 2 or layer 3 data container. Preferably, the generic format packet 14 takes the form of an Audio Video Transport Protocol (AVTP) Control Format (ACF) message defined in accordance with IEEE 1722, using a 64-bit stream ID as the generic format address 26 and 8 levels of QoS in accordance with IEEE 802.1Q for signaling priority. This allows a layer 2 Ethernet switch to act as a message forwarder 8.

[0070] It is not necessary to use ACF messages that use the flow ID as a universal format address. Other types of data containers may be used, such as layer 3 datagrams (i.e., "IP packets" or simply "packets") that use IP addresses as universal format addresses (e.g., based on IPv4 or IPv6), or layer 2 datagrams (i.e., "frames") that use MAC addresses as universal format addresses.

[0071] Figure 6 A data packet 131 is shown that is obtained from a CAN data frame that is passed from the protocol engine 51 to the message processor 61 .

[0072] Figure 7 Shows how to Figure 6 The data packet 131 shown in is converted into a common format packet 14.

[0073] like Figure 6 As shown, data in some of the fields, such as RTR, IDE, and DATA (i.e., payload data), is obtained by copying data from data packet 131. Data is added to other fields according to a predefined scheme, which may be based on an accept filter list (AFL) or a lookup table. Data is added to other fields based on data found in the fields in data packet 131. Although message processor 61 is implemented in hardware, it may be configured by CPU 18.

[0074] Because IEEE 1722 messages are typically encapsulated in Ethernet packets, the IEEE 802.1 header and 802.1Q header are not required, but are beneficial.

[0075] refer to Figure 8 , a vehicle communication network 31 is shown. The network 31 comprises a plurality of different buses 31, 32, 33, such as CAN and Ethernet. The network comprises a plurality of control units 32 which may take the form of microcontrollers connected to the buses 31, 32, 33. At least a portion of the control units 32 are network interface modules 71, 72 ( Figure 3 ) and the control unit 16 of the message forwarder 8. The vehicle communication network 31 is deployed in the vehicle 33.

[0076] refer to Fig. 9 , an industrial communication network 41 is shown. The network 41 comprises a plurality of different buses 31, 32, 33, such as CAN and Ethernet. The network comprises a plurality of control units 42 which may take the form of microcontrollers connected to the buses 31, 32, 33. At least some of the control units 42 are network interface modules 71, 72 ( Figure 3) and a control unit 16 of a message forwarder 8. The industrial communication network 41 is deployed in a plant, a machine or a system 43 (such as a manufacturing or processing system).

[0077] The message processors 61 , 62 may have one or more benefits.

[0078] The message processor 61, 62 can help provide consistency in how messages are forwarded, regardless of the bus type and whether the message arrives on the communication bus or is generated by the CPU. It can also provide configurable flexibility, for example, allowing messages to be forwarded to multiple destinations. In addition, the use of a common network stack reduces the degree of adaptation of the layer 3 software stack when new protocols are added. In addition, a common set of functions can be used regardless of the protocol, such as abstract QoS mechanisms (for example, mapped to IDs on CAN, 802.1Q PCP on Ethernet, and scheduling on FlexRay), abstract node addressing mechanisms (for example, mapped to IDs on CAN, MAC, VLAN, AVTP, or IPv4 on Ethernet), and unified timestamp mechanisms (for example, based on 802.1AS). In addition, it can simplify software maintenance when changing protocols (for example, porting a CAN-based control unit to Ethernet).

[0079] Revise

[0080] It will be appreciated that many modifications may be made to the embodiments described above.

[0081] The control unit may include more than two network interface modules. Two or more network interface modules may be of the same type, such as a CAN controller. Therefore, the control unit may be connected to more than two buses. A message repeater may be connected to more than two network interface modules. Therefore, the control unit may be connected to more than two buses of the same type. A message repeater may be connected to more than two network interface modules. Therefore, a message repeater may switch or route a universal format message between three or more message processors.

Claims

1. A hardware-implemented network interface module (71, 72), comprising: Protocol Engine (51, 52); a message processor (61, 62, 20) configured to, in response to receiving a data packet formatted according to a given communication protocol and comprising packet guide data (22) and payload data (23), generate a universal format packet (14) having a predetermined data format including a universal format header (24) and a payload (25), wherein the packet guide data is a protocol-dependent address, wherein the universal format header includes a universal format address generated according to the packet guide data, and wherein the payload includes the data packet; wherein the data packet formatted according to the given communication protocol is received from the protocol engine or from a unified network stack (9), Wherein the universal format address is not formatted according to the given communication protocol.

2. The hardware-implemented network interface module according to claim 1, wherein the universal format packet (14) having the predetermined data format is a layer 2 packet or a layer 3 packet.

3. The hardware-implemented network interface module according to claim 1, wherein the message processor (61, 62, 20) is configured to perform one or more operations selected from the following operations: Copying data from a first field in the packet guide data to a corresponding field in the universal format header (24); adding predetermined data to a second field in the universal format header; and Computed data is added to the common format header based on data from a first field in the packet guide data and / or computed data is added to a second field in the common format header based on data from a second field in the packet guide data.

4. The hardware-implemented network interface module of claim 1, wherein the message processor (61, 62, 20) is configured to extract a data packet formatted according to a given communication protocol and including packet guide data (22) and payload data (23) in response to receiving a common format packet (14) having a predetermined data format including a common format header (24) and a payload (25).

5. The hardware-implemented network interface module according to claim 1, wherein the common format packet (14) having the predetermined data format is a layer 2 frame.

6. The hardware-implemented network interface module according to claim 1, wherein the common format packet (14) having the predetermined data format is an IP packet.

7. The hardware-implemented network interface module of claim 1, wherein the given communication protocol is a FlexRay protocol.

8. The hardware-implemented network interface module of claim 1, wherein the given communication protocol is a Media Oriented Systems Transport Protocol.

9. The hardware-implemented network interface module (71, 72) according to claim 1, wherein the universal format packet (14) having the predetermined data format is readable by a UDP gateway.

10. The hardware implemented network interface module (71, 72) according to claim 1, wherein the given communication protocol is ISO 11898-1.

11. A hardware-implemented network interface module, comprising: Protocol Engine (51, 52); and A message processor (61, 62, 20) is configured to extract a data packet formatted according to a given communication protocol and including packet guide data (22) and payload data (23) in response to receiving a universal format packet (14) having a predetermined data format including a universal format header (24) and a payload (25), and the message processor (61, 62, 20) is configured to forward the data packet to the protocol engine or unified network stack (9), The packet boot data is a protocol-dependent address, wherein the universal format header includes a universal format address generated according to the packet boot data, the universal format address not being formatted according to the given communication protocol.

12. A central processing unit subsystem comprising: Central processing unit (18); Memory (19); A computer program stored in a memory or other storage, which, when executed by the central processing unit, causes the central processing unit to execute a message processor (61, 62, 20), the message processor (61, 62, 20) being configured to generate a universal format packet (14) having a predetermined data format including a universal format header (24) and a payload (25) in response to receiving a data packet formatted according to a given communication protocol and including packet guide data (22) and payload data (23), wherein the packet guide data is a protocol-dependent address, wherein the universal format header includes a universal format address generated according to the packet guide data, and wherein the payload includes the data packet, and wherein the universal format address is not formatted according to the given communication protocol.

13. A control unit (16), comprising: The hardware-implemented network interface module of claim 1, wherein the hardware-implemented network interface module is a first hardware-implemented network interface module (71), and the message processor is a first message processor (61), the first message processor (61) being configured to process data packets formatted according to a first communication protocol; A second hardware-implemented network interface module (72) comprising a second message processor (62) configured to process data packets formatted according to a second communication protocol; and A message forwarder (8) is configured to exchange a common format packet having the predetermined data format between the first message processor and the second message processor.

14. The control unit of claim 13, wherein the message forwarder is a layer 2 switch and / or a layer 3 router.

15. The control unit of claim 13, wherein the first communication protocol and the second communication protocol are different.

16. The control unit according to claim 13, further comprising: A third hardware-implemented network interface module includes a third message processor configured to process data packets formatted according to a third communication protocol.

17. The control unit according to claim 13, further comprising: Central processing unit subsystem (17); and The message forwarder is configured to perform exchanges between the central processing unit subsystem and the first message processor and / or the second message processor.

18. The control unit (16) according to claim 13, wherein the message forwarder (8) is configured to exchange common format packets using an Ethernet message gateway.

19. The control unit (16) according to claim 13, further comprising: a central processing unit subsystem (17); and The central processing unit subsystem is configured to allow direct access to the first message processor (61) and the second message processor (62) by bypassing the message forwarder (8).

20. A communication system (31), comprising: At least two sets of buses (31, 32); and At least one control unit (16) according to claim 13 is connected to the bus.

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