COMMUNICATION SYSTEM AND COMMUNICATION PROCEDURES WITH A STATUS MESSAGE

Description

[0001] The invention relates to a communication system with a communication network and a communication method for operating the communication network. The invention further relates to a network component. The communication network comprises a first group of network components and a second group of network components. Each network component has one port and another port, via which a network component of the same first or second group is connected for data transmission. Each network component also has a cross port, via which a network component of the other group is connected for data transmission.

[0002] The patent application EP 0 045 067 A1) discloses a time-division multiplex switching system with a plurality of switching modules for call handling and a plurality of port switching in each of the modules.

[0003] German patent DE 10 2004 030 561 B4 describes a transmission device for railcars. A primary repeater and a secondary repeater are installed in each railcar and each is configured to receive data transmitted by another repeater and to forward received data to another repeater. A primary trunk line connects the primary repeaters to each other. A secondary trunk line connects the secondary repeaters to each other. A trunk-trunk line connects the primary and secondary repeaters in each railcar. A trunk transmitter-receiver is installed in each repeater and configured to transmit and receive data to and from another repeater in a different railcar.A trunk-to-trunk transceiver is installed and configured in each repeater to transmit and receive data to and from the other repeater in the same railcar. A repeater controller is installed and configured to control the trunk-to-trunk transceiver and the trunk-to-trunk transceiver, forming a network. A station transceiver is installed and configured in each repeater to transmit and receive data to and from the repeater controller. A station is connected to and configured with the station transceiver to transmit and receive data to and from the station transceiver, with the primary trunk line, the secondary trunk line, and the trunk-to-trunk lines forming a conductor-like transmission line network.Each repeater that receives data from another repeater forwards the received data via the trunk-to-trunk line to another repeater in the same train car and via the trunk line to another repeater in the adjacent train car. Each repeater that receives the same data via the trunk line and via the trunk-to-trunk line forwards the data it received first.

[0004] Against this background, the object of the invention is to provide an improved communication system, an improved network component and an improved communication method.

[0005] This task is defined by independent claims 1, 9, 10 and 11. Dependent claims 2-8 define implementation details of the invention.

[0006] The invention relates to communication systems that operate using the Spanning Tree Protocol (STP), in particular the Multiple Spanning Tree Protocol (MSTP). A key feature of this protocol is that a network component is designated as the root bridge. The root bridge sends Bridge Protocol Data Units (BPDUs) to all other network components and determines the network configuration using the configuration data contained in the BPDU data packets. A significant disadvantage of this method is that the duration of a redundancy switchover is comparatively long and not deterministic (i.e., predictable). Redundancy switchover refers to the process of restoring a failed data connection (for example, by bypassing a physical connection).Accordingly, the invention is also based on the understanding that short redundancy switching times (i.e., the time between failure and availability of a data connection) are desirable.

[0007] The solution according to the invention solves this problem by configuring the network components to each send a status message containing the port states of the individual ports. Based on this status message, network components receiving the status message are informed about the port states of the sending network components. This information can be used for timely and deterministic redundancy switching.

[0008] A key advantage of the invention is that a root bridge (as known from STP) can be dispensed with. Instead, all network components send a status message, preferably in the form of a Bridge Protocol Data Unit (BPDU). Based on this status message, network components that receive the status message can react to the port states of the sending network component and, for example, change their own port states to trigger a redundancy switch.

[0009] The communication network is preferably a local area network (LAN) and further preferably designed as an Ethernet network.

[0010] The network components of the first and second groups are preferably interconnected in a linear network topology.

[0011] The respective network component is preferably a switch, more preferably an Ethernet switch. The respective port of the network component forms, in particular, an input for receiving data and an output for sending data.

[0012] The data connection to the network component of the same group provided via the first and subsequent ports, and the data connection to the network component of the other group provided via the cross port, is established, for example, by a wired connection of the network component of the same or other group to the port.

[0013] The status message is preferably structured in the form of a Bridge Protocol Data Unit (BPDU).

[0014] The port state can be, for example, a first state in which incoming or outgoing data frames are discarded and an incoming status message is not received and processed. This type of port state is often referred to technically as "discarding." The port state can also be a second state in which incoming or outgoing data frames are forwarded and an incoming status message is received, processed, and transmitted. This type of port state is often referred to technically as "forwarding." Ports can also assume other, undescribed port states.

[0015] According to a preferred embodiment of the communication system according to the invention, the respective network component is configured to send the status message to the port, the additional port, and the cross port. The status message contains a network component number that identifies the network component. The status message also contains a port number that identifies the port, the additional port, or the cross port of the network component from which the status message originates.

[0016] This represents a particularly convenient implementation of the status message, which allows the receiving network components to trigger and / or perform a redundancy switchover.

[0017] The port number includes, for example, a logical port number, which identifies the first port, the next port, and the cross port. Additionally, the port number includes, for example, a physical port number.

[0018] According to a further preferred embodiment of the communication system according to the invention, the network components are interconnected via a ladder structure. The first group is interconnected via a first ladder section of the ladder structure, and the second group is interconnected via a second ladder section. The first and second groups are interconnected via their respective cross ports, similar to rungs of the ladder structure.

[0019] The ladder structure is, in particular, the network topology according to which the network components are interconnected. This means that the network components do not need to be spatially arranged according to the ladder structure to form this network topology.

[0020] In a preferred training scenario, the network components are configured to perform a redundancy switchover based on a received status message. This switchover uses the network components to select a communication path for a data connection between two network components. This communication path bypasses a failed data connection between the two network components via the network infrastructure.

[0021] This further development demonstrates that the conductor structure is particularly suitable for redundancy switching in a communication system according to the invention. Furthermore, the further development reveals an advantageous method for redundancy switching in the communication system according to the invention.

[0022] Preferably, in the event of a failure of a data connection between two network components of the first or second group, an alternative communication path via network components of the second or first group is chosen.

[0023] According to a particularly preferred embodiment of the communication system according to the invention, the communication network is a network of a track-bound vehicle. The track-bound vehicle comprises several cars, with a pair of network components arranged in each car. Each pair comprises a network component of the first group and a network component of the second group, which are interconnected via the transverse ports.

[0024] This embodiment represents a particularly practical and desirable way of using the communication system according to the invention.

[0025] The communication network is preferably a Moving Local Area Network (MLAN) of the track-bound vehicle.

[0026] Preferably, the status message contains a car number representing a car in which the network component sending the status message is located.

[0027] Preferably, in the event of a failure of a data connection between two network components that form a pair, an alternative communication path is chosen via network components that form another pair in a different car.

[0028] In a preferred further training, the communication network serves as a control network and as an operator network for the track-bound vehicle.

[0029] In other words, the control network and the operator network are formed by a single, shared network. In contrast, with previous solutions, the control network and the operator network are physically and / or logically separated.

[0030] Combining the control network and the operator network into a single network reduces cabling costs, the number of network components, and the required installation space. It also reduces the effort required for network modifications. Furthermore, it simplifies operation, administration, and maintenance (OAM), as well as configuration and software updates. Finally, functional innovations, such as Time Sensitive Networking (TSN), can be implemented more easily because they do not need to be implemented separately for each network domain (control network and operator network).

[0031] The communication system according to the invention is particularly suitable for converging the control network and operator network into a single, unified network: This is because the duration of redundancy switching is reduced by the communication system according to the invention. Therefore, the communication system according to the invention is particularly advantageous for this type of converged communication network. This is because the maximum values ​​for redundancy switching times specified in networks of this type can be met by the communication system according to the invention. These maximum values ​​are specified differently for the various subsystems connected to the communication network – such as the passenger information system (FIS), the camera surveillance system (CCTV: Closed Circuit Television), the vehicle control system, etc.

[0032] Experts understand the term "control network" to mean a network comprising one or more components for vehicle control. This understanding is based on the knowledge that in modern rail vehicles, in addition to the classic control functions (e.g., drive and braking systems), numerous tasks are performed automatically. These include, for example, the operation and management of a system for distributing information to passengers and on-board staff, the automated operation of a restroom, the management of communication between the rail vehicle and the shore, etc. The corresponding components are interconnected via the control network for control and communication purposes.

[0033] Furthermore, experts understand the term "operator network" to mean a network that is physically and / or logically separate from the control network. For example, the passenger information system (FIS) and / or the CCTV system for monitoring the interior and exterior of the rail vehicle are connected to the operator network via data technology. The corresponding components of the FIS or CCTV system are interconnected via communication technology through the operator network.

[0034] The invention further relates to a track-bound vehicle with a communication network of the type described above.

[0035] The aforementioned task is further accomplished by a network component belonging to a first or second group of network components. This network component comprises one port and another port, each configured to establish a data connection with a network component of the same first or second group. The network component also includes a cross-port, configured to establish a data connection with a network component of the other group. The network component is configured to send a status message at regular intervals. This status message contains port status information, representing the state of the first port, the state of the second port, and the state of the cross-port.

[0036] The aforementioned task is further solved by a communication method for operating a communication network comprising a first group of network components and a second group of network components. Each network component has one port and another port through which a network component of the same first or second group is connected. The network components also have a cross-port through which a network component of the other group is connected. In this communication method, the network components send a status message at regular intervals. The status message contains port state information, representing the state of the first port, the state of the second port, and the state of the cross-port.

[0037] The invention further relates to a computer program product comprising instructions which, when the program is executed by a computing device, cause it to execute the communication method of the type described above.

[0038] The invention further relates to a provisioning device for the computer program product of the type described above, wherein the provisioning device stores and / or provides the computer program product. The provisioning device is, for example, a storage unit that stores and / or provides the computer program product. Alternatively and / or additionally, the provisioning device is, for example, a network service, a computer system, a server system, in particular a distributed, for example cloud-based, computer system and / or virtual computer system, which preferably stores and / or provides the computer program product in the form of a data stream.

[0039] The provision of the computer program takes the form of a program data block as a file, particularly as a download file, or as a data stream, particularly as a download data stream. This provision can also occur, for example, as a partial download consisting of several parts. Such a computer program is, for example, read into a system using the provisioning device, so that the communication method according to the invention is executed on a computer. The computer is, for example, a computing device of the network component.

[0040] For advantages, embodiments and design details of the track-bound vehicle according to the invention, the network component according to the invention, the communication method according to the invention, the computer program product according to the invention and the provisioning device according to the invention, reference can be made to the preceding description of the corresponding features of the communication system according to the invention.

[0041] An embodiment of the invention is explained with reference to the drawings. The drawings show: Figure 1 schematically shows the structure of an embodiment of a communication system according to the invention, Figure 2 schematically shows the process of an embodiment of a communication method according to the invention, Figure 3 a schematic representation of a conductor structure according to the embodiment of the communication system according to the invention, and Figure 4 a further representation of the embodiment of the communication system according to the invention.

[0042] Figure 1 Figure 1 shows a schematic representation of a communication system 1 with a communication network 2, which is shown in relation to a track-bound vehicle 3 and is physically installed on the track-bound vehicle 3.

[0043] The track-bound vehicle 3 is a rail vehicle 4, for example a multiple unit train, with several cars 5 to 9. Cars 5 and 9 are end cars. Cars 6 to 8 are arranged between end cars 5 and 9.

[0044] Communication network 2 comprises several network components 51, 52, 61, 62, 71, 72, 81, 82, 91, 92, which are physically and data-wise interconnected and each configured as a switch. Network components 51, 61, 71, 81, and 91 form a first group 20. Network components 52, 62, 72, 82, and 92 form a second group 30.

[0045] The network components 51, 52, 61, 62, 71, 72, 81, 82, 91, 92 each have a first port P1, a second (cross) port PQ and a third port P3.

[0046] The first port P1 connects network components 61, 71, 81, and 91 of the first group 20 to network components 51, 61, 71, and 81 of the first group 20. Additionally, network components 62, 72, 82, and 92 of the second group 30 are connected to network components 52, 62, 72, and 82 of the second group 30 via the first port P1.

[0047] The network components 51, 61, 71, and 81 of the first group 20 are connected via the third port P3 to the network components 61, 71, 81, and 91 of the first group 20, respectively. Additionally, the network components 52, 62, 72, and 82 of the second group 30 are connected via the third port P3 to the network components 62, 72, 82, and 92 of the second group 30, respectively.

[0048] Network components 51 and 52 form a pair 50, which is located in car 5. Network components 61 and 62 form a pair 60, which is located in car 6. Network components 71 and 72 form a pair 70, which is located in car 7. Network components 81 and 82 form a pair 80, which is located in car 8. Network components 91 and 92 form a pair 90, which is located in car 9.

[0049] The network components are interconnected in a data-technical manner, similar to a ladder structure. The in Figure 3The ladder structure shown in Figure 100 illustrates this network topology. The in Figure 3 The communication network 2 shown is in the same way as the one in Figure 1 The communication network shown is set up as network 2. Identical and functionally equivalent elements are marked with the same reference symbols.

[0050] According to Figure 3 Network components 51, 61, 71, 81, and 91 are connected linearly along ladder string 200. Network components 52, 62, 72, 82, and 92 are connected linearly along ladder string 300. Each pair 50, 60, 70, 80, and 90 is connected via their respective cross port (second port) PQ, similar to a ladder rung 500, 600, 700, 800, and 900, respectively.

[0051] Figure 2 schematically shows the sequence of an exemplary embodiment of the communication method according to the invention.

[0052] In process step A, the in Figure 1The network components shown send a status message at time T1. That is, each network component sends the status message via the first port P1, the second port PQ, and the third port P3.

[0053] The status message contains the following information: a car number of the car in which the network component sending the status message is located, a network component number that identifies the network component sending the status message, a port number that identifies the first port P1, the second port PQ and the third port P3 from which the status message was sent, and a port state information PZ that represents the port state of the first port P1, the port state of the second port PQ and the port state of the third port P3.

[0054] The port state can be, for example, a first state D, in which incoming or outgoing data frames are discarded and an incoming status message is not received and processed. This type of port state is often referred to technically as "discarding." The port state can also be, for example, a second state F, in which incoming or outgoing data frames are forwarded and an incoming status message is received, processed, and transmitted. This type of port state is often referred to technically as "forwarding."

[0055] The following example considers a case in which the data connection between the third port P3 of network component 61 and the first port P1 of network component 71 fails. This case is described in Figure 4 depicted. The in Figure 4 The communication network 2 shown is in the same way as the one in the Figure 1 and 3The communication network shown is set up as network 2. Identical and functionally equivalent elements are therefore marked with the same reference symbols.

[0056] In the Figure 4 In the case shown, port P1 of network component 71 has assumed port state D after the failure of connection 14. The status message ST, which the network component sends in process step A, is received by network component 72 in process step B. Based on the status message, network component 72 can determine that port P1 of network component 71 has port state D.

[0057] Based on the knowledge of the failed connection, a redundancy switch is performed in process step C. In process step C1, a communication path 13 is selected using the network components, which bypasses the failed connection between network components 61 and 71. In this case, the alternative communication path 13 is selected via network components 62 and 72. In other words, for the failure of the connection between network components 61 and 71 of the first group 20, an alternative communication path is selected via network components 62 and 72 of the second group 30. The conductor structure 100 provides the basis for the selection of the alternative communication path.

[0058] The network component 72 triggers the communication path 13, for example, by switching the port P1 of the network component 72 from port state D to F in a procedure step C2 in order to enable communication via the communication path 13.

[0059] Another example, not shown, is the failure of the data connection between network components 62 and 72. In this case, port P1 of network component 71 is switched from port state D to F.

[0060] Another example, not shown, is the failure of network component 71. In this case, port P1 of network component 72 is switched from port state D to F, and port P1 of network component 82 is switched from port state D to F.

Claims

1. Network component of a first or second group of network components, comprising: - a port (P1) and a further port (P3), which in each case are configured to provide a connection in terms of data to a network component of the same first or second group (20, 30), characterised by - a cross-port (PQ), which is configured to provide a connection in terms of data to a network component of the other group (30, 20) in each case, wherein the network component (51, 52, 61, 62, 71, 72, 81, 82, 91, 92) is configured to emit (A) a status message (ST) at regular temporal intervals in each case, wherein the status message (ST) contains an item of port status information, which represents a port status (F, D) of the port (P1), a port status of the further port (P3) and a port status of the cross-port (PQ).

2. Communication system with a communication network (2), which comprises a first group (20) of network components (51, 61, 71, 81, 91) and a second group (30) of network components (52, 62, 72, 82, 92), wherein the network components in each case are defined according to claim 1.

3. Communication system according to claim 2, characterised in that the respective network component is configured to emit the status message at the port (P1), at the further port (P3) and the cross-port (PQ) and the status message (ST) contains - a network component number, which identifies the network component, and - a port number, which identifies the port (P1), the further port (P3) or cross-port (PQ) of the network component, from which the status message is sent.

4. Communication system according to claim 2 or 3, characterised in that the network components are interconnected in terms of data according to a ladder structure, wherein the first group are interconnected in terms of data in the manner of a first rail (200) of the ladder structure (100) and the second group are interconnected in terms of data in the manner of a second rail (300) of the ladder structure (100), and wherein the first group (20) and second group (30) are interconnected in terms of data via the respective cross-port (PQ) in the manner of a rung (500, 600, 700, 800, 900) of the ladder structure (100).

5. Communication system according to claim 4, characterised in that the network components are configured to carry out (C) a redundancy switchover on the basis of a received status message, in which a communication path (13) for a connection in terms of data between two network components (61, 71) is chosen (C1) by means of the network components, which bypasses a failed connection in terms of data between the two network components via the ladder structure (100).

6. Communication system according to at least one of the preceding claims, characterised in that the communication network (2) is a network of a rail-bound vehicle (3), which comprises multiple cars (5, 6, 7, 8, 9), a pair (50, 60, 70, 80, 90) of network components is arranged in each car (5, 6, 7, 8, 9), wherein the respective pair comprises a network component of the first group (20) and a network component of the second group (30), which are interconnected in terms of data via the cross-ports (PQ).

7. Communication system according to claim 6, characterised in that the communication network is used as a control network as well as an operator network of the rail-bound vehicle (3).

8. Rail-bound vehicle (3) with a communication network (2) according to at least one of the preceding claims 2 to 7.

9. Communication method for operating a communication network (2), which comprises a first group (20) of network components (51, 61, 71, 81, 91) and a second group (30) of network components (52, 62, 72, 82, 92), wherein the network components in each case have - a port (P1) and a further port (P3), via which in each case a network component of the same first or second group (20, 30) is connected in terms of data, and are characterised by - a cross-port (PQ), via which a network component of the respective other group (30, 20) is connected in terms of data, wherein the network components in each case emit (A) a status message at regular temporal intervals, wherein the status message (ST) contains an item of port status information (PZ), which represents a port status (F, D) of the port (P1), a port status of the further port (P3) and a port status of the cross-port (PQ).

10. Computer program product, comprising commands which, when executed by a computing facility, prompt said computing facility to carry out the communication method according to claim 9.

11. Provision apparatus for the computer program product according to claim 10, wherein the provision apparatus stores and / or provides the computer program product.