Transferring data between media redundancy protocol rings

Abstract

The invention relates to a communication method and to a communication system (1) for transmitting data via a communication network (2) that has a first subnetwork (6) with a first media redundancy protocol ring (7) and at least one second subnetwork (8) with a second media redundancy protocol ring (9). In order to improve the transmission of data via a communication network of this type, a data packet (136) that is coded according to the media redundancy protocol is transmitted between the first and second subnetworks (6, 8), and the data packet (136) is assigned identification information (ID32, ID34) that corresponds to a virtual local area network (VLAN) in which the first and second subnetworks (6, 8) are embedded.

Description

[0001] Description

[0002] Transferring data between media redundancy protocol rings

[0003] Technical area

[0004] The invention relates to a method for transmitting data via a communication network which has at least a first subnetwork with a first media redundancy protocol ring and at least a second subnetwork with a second media redundancy protocol ring.

[0005] Technical background

[0006] Procedures for transmitting data over a communications network are generally known.

[0007] EP 2 409458 A1 describes a method for operating a network, in particular an Ethernet network. The network has a ring network topology in which network devices are connected to each other via their data ports via data lines and exchange control data and user data via the data lines using protocols. The protocols prevent network traffic from being relayed via specific data ports of individual network devices, with the exception of network traffic for controlling and / or monitoring media redundancy. This prevents endless circulating network traffic in physical meshes of the network. Two different protocols are processed in parallel on the network devices within the network.The operation of at least two redundancy protocols is made possible by either assigning control over the data ports to be blocked to a single redundancy protocol, or selecting parameters for at least two redundancy protocols and / or arranging the working procedures of the redundancy protocols in such a way that one redundancy protocol does not block connections that the other redundancy protocol considers to be active. The protocols used are the Rapid Spanning Tree Protocol (RSTP) and / or the Media Redundancy Protocol (MRP). The Media Redundancy Protocol (hereinafter: Media Redundancy Protocol or abbreviated MRP) is a protocol for high-availability networks used in critical automation applications. MRP is based on a ring topology and guarantees a fast recovery time of a maximum of 200 milliseconds after a switch or line failure.MRP operates at the data link layer (OSI Layer 2) of Ethernet switches. It uses a redundancy manager (MRM) to close the ring and forward traffic.

[0008] The "Frame Replication and Elimination for Reliability" (FRER) protocol is also fundamentally known as a redundancy protocol. FRER is a protocol that aims to ensure seamless network availability in real-time applications. FRER is based on the idea of ​​transmitting each frame copy over multiple separate paths and then removing duplicates at one or more points in the network. FRER operates at the data link layer (OSI Layer 2) of Ethernet switches. It uses a sequence numbering scheme to identify and remove duplicates.

[0009] Summary of the invention

[0010] Against this background, the object of the present invention is to improve the transmission of data over a communications network of the type mentioned above. In particular, the object of the present invention is to enable MRP-based communication between the media redundancy protocol rings of the communications network of the type mentioned above.

[0011] This object is achieved according to the invention by a method of the type mentioned above, in which a data packet is transmitted within the first or second subnetwork using the media redundancy protocol. The data packet is assigned identification information corresponding to a virtual local area network in which the first and second subnetworks are embedded. The data packet is transmitted between the first and second subnetworks based on the identification information.

[0012] The invention is based on the recognition that communication networks are desired that enable seamless communication between two or more media redundancy protocol rings. This is particularly desirable for the application of novel communication protocols, which are used, for example, for time-critical communication in safety-critical systems. A further recognition of the invention is that the transmission of data packets using the media redundancy protocol has so far only been intended for communication within a media redundancy protocol ring. Suitable solutions for communication between two or more media redundancy protocol rings are often not supported by network components such as switches.

[0013] The method according to the invention provides a solution which enables interoperability between the media redundancy protocol and other communication protocols, in which data packets which are transmitted in previous solutions using the media redundancy protocol within the first or second subnetwork can be transmitted between two or more MRP rings.

[0014] The term "virtual local area network" (VLAN) refers to a logical network based on a physical Ethernet network. VLANs enable devices to be grouped based on their requirements without laying new cables or making major changes to the existing network infrastructure. VLANs can be used to improve the security, performance, and flexibility of a network.

[0015] The phrase "assigning identification information to the data packet" should preferably be understood to mean that the identification information is added to the data packet. For example, the identification information is set as part of a header of the data packet. Preferably, the identification information is assigned to the data packet before the data packet is transmitted between the first and second subnetworks.

[0016] The wording according to which the first and second subnetworks are embedded in the VLAN is preferably understood by the person skilled in the art to mean that this VLAN at least connects the first and second subnetworks.

[0017] Embodiments of the invention

[0018] According to a preferred embodiment of the method according to the invention, the identification information is assigned to the data packet as a VLAN ID according to the IEEE 802.1Q standard. This embodiment cleverly exploits the fact that the use of the VLAN ID is generally not intended for MRP data packets. Accordingly, the VLAN ID for MRP packets is generally "0" or there is no VLAN TAG present at all. The formulation according to which the VLAN ID is "assigned" to the data packet should therefore preferably be understood to mean that the VLAN ID of the MRP data packet is set to something other than "0". For example, the MRP data packet is provided with a specifically designated VLAN ID.

[0019] A VLAN ID is, according to technical understanding, a unique numeric identifier for a virtual LAN (VLAN). VLANs are logical broadcast domains based on a physical Ethernet network. Each VLAN is identified by a VLAN ID, which can be between 1 and 4095. The VLAN ID is transmitted in a VLAN tag within the Ethernet frame. The VLAN tag is an additional field inserted within the Ethernet header. The VLAN tag contains the VLAN ID and the priority of the Ethernet frame. The VLAN ID is used by switches and routers to determine which VLAN an Ethernet frame belongs to. Only frames with the same VLAN ID are forwarded within a VLAN. IEEE 802.1Q is a standard of the Institute of Electrical and Electronics Engineers (IEEE) that defines the use of VLANs on Ethernet networks.

[0020] According to a further preferred embodiment of the method according to the invention, the virtual local area network (VLAN) comprises network components which are operated according to a redundancy protocol based on Frame Replication and Elimination for Reliability (FRER).

[0021] The redundancy protocol, based on Frame Replication and Elimination for Reliability (FRER), is preferably implemented according to the IEEE 802.1cb standard.

[0022] The network components that operate according to the redundancy protocol based on Frame Replication and Elimination for Reliability are also referred to below as FRER network components.

[0023] Accordingly, the VLAN in which the first and second media redundancy protocol rings are embedded comprises a network operated according to the FRER protocol. For example, the respective first and second subnetworks contain MRP components or MRP devices operated according to MRP, and additionally FRER network components or FRER devices operated according to FRER. At least the MRP components or devices are constructed within the subnetwork according to a ring architecture. In a preferred development of the communication method according to the invention, the identification information is assigned to the data packet by means of at least one of the network components. This represents a particularly expedient embodiment, because the FRER network component is particularly suitable for assigning the identification information to the data packet.

[0024] According to a further preferred embodiment of the method according to the invention, the communications network is at least partially a communications network of a track-bound vehicle, in particular a rail vehicle. The rail vehicle is, for example, a multiple unit.

[0025] The application of the method according to the invention to communication networks that are at least partially part of a rail-bound vehicle is particularly expedient. This is because, particularly in the field of rail-bound vehicles, there will be situations during the gradual modernization of communication networks in which the media redundancy protocol must be operated jointly (i.e., in parallel and simultaneously) with a redundancy protocol based on Frame Replication and Elimination for Reliability (FRER). This is particularly the case when communication networks in rail-bound vehicles are modernized after delivery and a longer period of operation: In this case, it is often not possible to replace the entire communication network of the vehicle (without great expense), but components that communicate according to the media redundancy protocol must be able to interact with innovative, subsequently added redundancy protocols.

[0026] In a further preferred embodiment of the method according to the invention, the first subnetwork is data-technically connected to the second subnetwork via a first connection and at least one second connection. The identification information identifies the first connection or the second connection. Preferably, the second connection is physically redundant to the first connection.

[0027] This configuration of the communications network and the corresponding embodiment of the method according to the invention are particularly advantageous when the VLAN comprises network components that operate according to FRER. In this case, the first and second connections are used for the parallel transmission of the frame copy on different paths (namely the first and second connections) between the first and second subnetworks. The VLAN IDs of the FRER packets used for the separate paths can therefore be used for the data packet for transmission between the first and second subnetworks. In other words: the identification information assigned to the data packet according to the invention corresponds to the VLAN ID assigned to one of the FRER packets transmitted on separate paths.

[0028] According to a further preferred embodiment of the communication method according to the invention, the data packet is transmitted from the first subnetwork to the second subnetwork. Within the second subnetwork, the data packet is assigned further identification information, which differs from the first identification information.

[0029] This has the advantage that the data packet can be identified within the second subnetwork as a data packet originating from the first subnetwork. This is desirable to avoid a potential loop that redirects the data packet back to the first subnetwork. In particular, in an embodiment of the method in which the identification information identifies the first connection and / or the second connection, the assignment of additional identification information is particularly advantageous. Without this assignment, there is a probability that the data packet will be redirected back to the first subnetwork via this identified connection.

[0030] The aforementioned object is further achieved by a computer program. The computer program comprises instructions which, when executed by a computing device of the communications network, cause the computing device to execute the communication method of the type described above. The invention further relates to a computer program product comprising a computer program of this type. The computing device is preferably, at least in part, a computing device of a rail-bound vehicle and / or a computing device of a land-based facility.

[0031] The object stated above is further achieved by a provision device for the computer program of the type described above, wherein the provision device stores and / or provides the computer program. The provision device is, for example, a storage unit that stores and / or provides the computer program. Alternatively and / or additionally, the provision 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 stores and / or provides the computer program product preferably in the form of a data stream. The provision takes place in the form of a program data block as a file, in particular as a download file, or as a data stream, in particular as a download data stream, of the computer program.This provision can also be made, for example, as a partial download consisting of multiple parts. Such a computer program is, for example, read into a system using the provisioning device, so that the method according to the invention is executed on a computer.

[0032] The aforementioned object is further achieved by a communication system for transmitting data over a communication network. The communication network comprises a first subnetwork with a first media redundancy protocol ring and at least one second subnetwork with a second media redundancy protocol ring. The communication network is configured to transmit a data packet using the media redundancy protocol within the first or second subnetwork. A network component is configured to assign identification information to the data packet, which corresponds to a virtual local area network (VLAN) in which the first and second subnetworks are embedded. The communication network is configured to transmit the data packet between the first and second subnetworks based on the assigned identification information.

[0033] The aforementioned object is further achieved by a track-bound vehicle comprising a communications system of the type described above. The track-bound vehicle is preferably a rail vehicle, for example, a multiple unit.

[0034] The aforementioned object is further achieved by a system comprising a rail-bound vehicle of the type described above and a land-based facility. The system has a communications system of the type described above. A communications link of the communications system preferably establishes a data connection between the vehicle and the land-based facility.

[0035] The land-based facility includes, for example, a signal box with a communication system of the type described above.

[0036] The communication system is therefore part of the track-bound vehicle and / or part of the land-based facility.

[0037] For advantages, embodiments and design details of the inventive

[0038] Computer program, the provision device according to the invention, the communication system according to the invention and the track-bound vehicle according to the invention and the system according to the invention, reference can be made to the above description of the corresponding method features of the communication method according to the invention for transmitting data via a communication network.

[0039] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identities are included.

[0040] Exemplary embodiments of the drawing

[0041] Figure 1 shows schematically the structure of an embodiment of a communication system according to the invention,

[0042] Figure 2 shows schematically the sequence of a first embodiment of a communication method according to the invention and

[0043] Figure 3 shows schematically the sequence of a second embodiment of a method according to the invention.

[0044] Detailed description of the implementation examples

[0045] Figure 1 shows a schematic representation of a communication system 1 with a communication network 2, which is shown in relation to a rail-bound vehicle 3 and is physically installed on the rail-bound vehicle 3. The rail-bound vehicle 3 is a rail vehicle 4, for example, a multiple unit.

[0046] The communications network 2 comprises several network components 10, 12, 14, and 16, which are interconnected for data purposes and each configured as a switch. Network components 10, 12, 14, and 16 operate according to a redundancy protocol based on Frame Replication and Elimination for Reliability (FRER). This redundancy protocol is referred to below as the FRER protocol.

[0047] The communications network 2 also includes network devices 20, 22, 24, and 26, which are connected to each other and to the network components 10, 12, 14, and 16 for data transmission. The network devices 20, 22, 24, and 26 are each operated according to the Media Redundancy Protocol (MRP). These network devices 20, 22, 24, and 26 are also referred to below as MRP network devices. The communications network 2 includes a first subnetwork 6 with a first media redundancy protocol ring 7 (hereinafter: MRP ring 7), which has a ring structure, and a second subnetwork 8 with a second media redundancy protocol ring 9 (hereinafter: MRP ring 9), which has a ring structure.

[0048] Network components 10, 12 and network devices 20 and 22 are part of the first subnetwork 6 and are interconnected in the ring structure of the MRP ring 7. Network components 14, 16 and network devices 24 and 26 are part of the second subnetwork 8 and are interconnected in the ring structure of the MRP ring 9.

[0049] The subnetworks 6 and 8 are connected to each other via two redundant connections 32 and 34.

[0050] In the first exemplary embodiment shown, a transmitter (talker) 28 is provided, which sends a data packet to a receiver (listener) 30 using the FRER protocol (hereinafter also referred to as a FRER data packet). According to the FRER protocol, this FRER data packet is duplicated by network component 10. The redundant data packets reach network component 16 via the other network components 12 and 14. One of the two redundant data packets is eliminated at network component 16. The remaining data packet is forwarded to receiver 30. During this communication between transmitter 28 and receiver 30, it must be taken into account that network devices 20, 22, 24, and 26 in the respective media redundancy ring 7 or 9 are operated according to the media redundancy protocol. In the first embodiment shown, this results in only one possible path being active between the network components 10 and 12, namely via the network device 20.For example, network device 22 blocks one of its ports 22a in its role as redundancy manager due to the requirements of the media redundancy protocol. The same applies analogously to the path between network components 14 and 16.

[0051] The method according to the invention relates to communication between network devices 20 or 22 and 24 or 26, which are located in different media redundancy rings 7 and 9. In other words, there is a desire to transmit data packets, which are transmitted using the media redundancy protocol within the first or second subnetwork 6 or 8, from one subnetwork 6 or 8 to another subnetwork 8 or 6. These network devices 20, 22, 24, and 26 are each operated according to the media redundancy protocol (MRP) and, for this reason, are not capable of communicating from one media redundancy ring 7 or 9 with another media redundancy ring 9 or 7 in previous solutions. The method according to the invention provides a solution for achieving this type of communication (between two MRP network devices in different MRP rings).

[0052] For the transmission of a data packet between the network unit 20 or 22 and the network unit 24 or 26, one of the connections 32 and 34 between the MRP rings 7 and 9 must be used (in the embodiment shown, these are the only connections between the two MRP rings 7 and 9).

[0053] In the first exemplary embodiment of the communication method according to the invention shown in Figure 2, a data packet 136 is provided by the network device 20 in a first method step A. This is a data packet 136 which is transmitted within the subnetwork 6 or 8 using the media redundancy protocol (hereinafter also referred to as the MRP data packet).

[0054] Due to its transmission according to the Media Redundancy Protocol, this MRP data packet 136 has a VLAN tag header in the Ethernet frame according to IEEE 802.1Q. For data packets according to the Media Redundancy Protocol, the VLAN ID in the VLAN tag header is always set to "0" (or there is no VLAN tag at all). Only the so-called priority tag is configured differently for MRP data packets.

[0055] This MRP data packet 136 is transmitted by the network device 20 in a method step B and received by the network component 10 and / or 12 in a method step C. According to the first exemplary embodiment described with reference to Figures 1 and 2, both network components 10 and 12 are configured to assign identification information ID32 or ID34 to the data packet 136. Accordingly, in a method step D, the network component 10 or 12 assigns identification information ID32 or ID34 to the MRP data packet 136, which corresponds to a virtual local area network (VLAN) in which the first subnetwork 6 and the second subnetwork 8 are embedded. This is achieved by providing the VLAN ID in the data packet with a value other than "0".

[0056] In the first exemplary embodiment of the method according to the invention, the VLAN ID selected for the MRP data packet corresponds to a VLAN ID used in the same communications network 2 for the FRER data packet described above. For example, it is a VLAN ID assigned by network component 10, which identifies connection 32, or a VLAN ID assigned by network components 12, which identifies connection 34. The FRER data packet described above is also transmitted via this connection 32 or 34.

[0057] In a method step E, the MRP data packet is transmitted via the connections 32 and 34 to the second subnetwork 8.

[0058] In a method step F, the MRP data packet is received by network component 14 or 16. In a method step G, network component 14 or 16 assigns the MRP data packet a new VLAN ID ID38, which differs from the VLAN IDs ID32 and ID34 that identify connection 32 and 34, respectively. In this way, MRP data packet 136 is identified as originating from first subnetwork 6. Furthermore, this prevents MRP data packet 136 from being redirected from second subnetwork 8 back to first subnetwork 6.

[0059] In the first exemplary embodiment described above, in which both network components 10 and 12 are configured to assign a VLAN ID ID32 or ID34 to the MRP data packet 136, the MRP data packet 136 can be transmitted redundantly via connections 32 and 34 in method step E. This can lead to the receiving network device 24 or 26 receiving duplicated MRP data packets. The receiving network device 24 or 26 can handle this using the "planned duplication" feature according to the Profinet standard.

[0060] A second exemplary embodiment of the method according to the invention differs from the first exemplary embodiment in that either the network component 10 or the network component 12 is set up to assign a VLAN ID ID32 or ID34 to the MRP data packet 136. In this case, the MRP data packet 136 is transmitted to the second subnetwork 8 either via the connection 32 or via the connection 34 in a method step EE. If one of these connections 32 or 34 is lost (for example due to physical separation), this can lead to a total failure of the communication of MRP packets between the first and second subnetworks 6 and 8. For this purpose, a network control device (not shown) monitors the communication network 2 in a method step HH. In a method step JJ, if the connection 32 or 34 is lost, the communication network 2 is reconfigured if necessary such that the network component 12 or10 is configured to assign the VLAN ID ID34 or ID32 to the MRP data packet. In this way, the data packet 136 can be transmitted over the existing connection 34 or 32 in method step EE. Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples, and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims

Patent claims 1. Communication method for transmitting data via a communication network (2) which has a first subnetwork (6) with a first media redundancy protocol ring (7) and at least one second subnetwork (8) with a second media redundancy protocol ring (9), characterized in that • a data packet (136) is transmitted using the media redundancy protocol within the first or second subnetwork (6, 8), • the data packet (136) is assigned identification information (ID32, ID34) (D), which corresponds to a virtual local area network (VLAN) in which the first and second subnetwork (6, 8) are embedded, • the data packet (136) is transmitted between the first and second subnetwork (6, 8) based on the assigned identification information (ID32, ID34) (E).

2. Communication method according to claim 1, characterized in that the identification information is assigned to the data packet (136) as a VLAN ID according to the IEEE 802.1Q standard.

3. Communication method according to claim 1 or 2, characterized in that the virtual local area network (VLAN) comprises network components (10, 12, 14, 16) which are operated according to a redundancy protocol based on Frame Replication and Elimination for Reliability (FRER).

4. Communication method according to claim 3, characterized in that the identification information (ID32, ID34) is assigned to the data packet (136) by means of at least one of the network components (10, 12, 14, 16).

5. Communication method according to at least one of the preceding claims, characterized in that the communication network (2) is at least partially a communication network of a track-bound vehicle (3), in particular a rail vehicle (4).

6. Communication method according to at least one of the preceding claims, characterized in that the first subnetwork is data-technically connected to the second subnetwork via at least a first connection (32) and a second connection (34) and the identification information (ID32, ID34) identifies the first connection (32) or second connection (34).

7. Communication method according to at least one of the preceding claims, characterized in that the data packet (136) is transmitted (E) from the first subnetwork (6) to the second subnetwork (8) and within the second subnetwork (8) the data packet (136) is assigned further identification information (ID38) which differs from the identification information (ID32, ID34).

8. A computer program comprising instructions which, when executed by a computing device of the communication network, cause the computing device to carry out the communication method according to at least one of the preceding claims 1 to 7.

9. A provision device for the computer program product according to claim 8, wherein the provision device stores and / or provides the computer program.

10. Communication system for transmitting data via a communication network (2), comprising: a first subnetwork (6) with a first media redundancy protocol ring (7) and - at least one second subnetwork (8) with a second media redundancy protocol ring (9), characterized in that - the communication network (2) is configured to transmit a data packet (136) using the media redundancy protocol within the first or second subnetwork (6, 8), a network component (10, 12, 14 and 16) is configured to assign to the data packet an identification information item (ID32, ID34) which corresponds to a virtual local area network (VLAN) in which the first and second subnetwork (6, 8) are embedded, and - the communication network (2) is configured to transmit the data packet (136) between the first and second subnetworks (6, 8) based on the associated identification information (ID32, ID34).

11. A track-bound vehicle with a communication system according to claim 10.

12. A system comprising a track-bound vehicle (3) and a land-based facility, the system comprising a communication system according to claim 10.

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