Communication system and communication method

Abstract

The embodiment of the invention provides a communication system and a communication method, and the communication system comprises an access layer formed by N1 APL switches with completely same hardware and software, and a convergence layer formed by N2 cascaded APL field switching devices. The first field switch in the convergence layer establishes APL Ethernet connection with downlink ports of different APL power switches, and N3 field devices are used for accessing a downlink port of a target field switch. According to the communication system, independent access of an upper-layer redundant network is achieved through the non-APL Ethernet, the physical connection standard of lower-layer equipment is unified through the full-link APL Ethernet, in this way, support can be provided for parallel operation of at least two redundant networks in a single system, the redundant networks are not related to each other, and independent isolated networks are formed; namely, the isolation network and the redundant network are compatible in the same communication system at the same time.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a communication system and communication method. Background Technology

[0002] Advanced Physical Layer (APL) is a new Ethernet physical layer standard based on the IEEE 802.3cg 10BASE-T1L specification. It employs a two-wire mode and supports intrinsic safety and Power over Ethernet. The emergence of APL technology has revolutionized the way field devices are connected in process industries, enabling convenient access to industrial Ethernet networks and allowing Ethernet protocols to be directly applied to the field device layer, greatly improving the efficiency of field device management and data communication. Currently, APL Ethernet is widely used in process industry automation control systems.

[0003] In modern industrial distributed control systems, network security and reliability are crucial considerations in system network architecture, leading to the development of network structures such as isolated networks and direct-connected networks. Isolated networks prioritize high security, high reliability, and logical isolation, effectively mitigating control system failures caused by single-point network failures and network storms. Direct-connected networks, on the other hand, are suited for high-speed, low-latency point-to-point real-time control requirements. However, existing industrial distributed control systems cannot simultaneously meet the differentiated network structure requirements of both isolated and direct-connected networks. Summary of the Invention

[0004] This application provides a communication system and method for simultaneously achieving compatibility between redundant networks and isolated networks.

[0005] In a first aspect, embodiments of this application provide a communication system, the communication system comprising: N1 APL power switches, each with identical hardware and software configurations, and each APL power switch is used to independently access the corresponding redundant network via a non-APL Ethernet network, where N1 is an even number. N2 APL field switches are cascaded via APL Ethernet; wherein, among the cascaded APL field switches, one uplink port of the first APL field switch is connected to the downlink port of the first power switch among the N1 APL power switches via APL Ethernet, and one uplink port of the last APL field switch is connected to the downlink port of the second power switch among the N1 APL power switches via APL Ethernet, and N2 is an integer greater than 1; The downlink port of the APL field switch is used to connect N3 APL field devices via the APL Ethernet, where N3 is a positive integer.

[0006] Optionally, both the APL power switch and the APL field switch are configured with a multicast MAC address forwarding table. The communication system includes a first device and a second device. The first device is the APL power switch, and the second device is the APL field switch that communicates with the APL power switch. The second device is used to send uplink multicast data to the uplink port corresponding to the first device through the corresponding downlink port according to the multicast MAC address forwarding table; The first device is used to send downlink unicast data to the corresponding downlink port of the second device through the corresponding uplink port, based on the multicast MAC address forwarding table.

[0007] Optionally, the APL power switch and the APL field switch are configured to receive data from their own downlink ports and forward it to their own uplink ports.

[0008] Optionally, the communication system is configured such that when the APL field device sends uplink redundant data packets to the target redundant network, it adds a VLAN tag of the target redundant network to the uplink redundant data packets and performs an operation to remove the VLAN tag in the target redundant network. When the target redundant network sends the downlink redundant data packet to the target APL field device, the target redundant network sends the downlink redundant data packet to the corresponding APL power switch. The corresponding APL power switch adds the VLAN tag to the downlink redundant data packet and forwards it to the corresponding APL field switch. After the corresponding APL field switch removes the VLAN tag, it sends the downlink redundant data packet to the target APL field device.

[0009] Optionally, the communication system is configured to disable the Layer 2 network flooding function for broadcast and multicast frames for the APL power switch and the APL field switch.

[0010] Optionally, the communication system is configured such that, for a unicast frame from any target device among the APL power switch and the APL field switch, the target device receives an ARP request sent by its upper or lower layer network. When the ARP request is an ARP request from a third device in the communication system to query the fourth device, the target device records the IP address and MAC address of the third device and records the MAC address and source port of the third device in a Layer 2 MAC address table. The target device queries its local configuration to see if the third and fourth devices are allowed to communicate across networks. If cross-network communication is allowed, the target device sends an ARP request to the fourth device. Upon receiving the ARP request, the fourth device establishes a mapping relationship between the IP address and MAC address of the third device in its own ARP table, and forwards the request directly to the port of the third device through the record in the Layer 2 MAC address table, sending an ARP response packet to the third device. The fourth device's MAC address and source port are also recorded in the Layer 2 MAC address table.

[0011] Optionally, the target device joins the multicast group to be forwarded via the IGMP protocol, receives or sends redundant data from the multicast group, parses the data through the application layer proxy service of the communication system, and retransmits the parsed data through a specified downlink port.

[0012] Optionally, the redundant network includes a first redundant network and a second redundant network, and the uplink and downlink ports of the APL power switch are both configured with a first VLAN rule; The first VLAN rule includes: the uplink port of the APL power switch is configured as the first VLAN, and no VLAN tag is added to the data frames of the first VLAN; the APL power switch connected to the first redundant network allows the data frames of the second VLAN to pass through; the APL power switch connected to the second redundant network allows the data frames of the third VLAN to pass through, and no VLAN tag is added to the data frames of the second VLAN and the data frames of the third VLAN. The downlink port of the APL power switch is configured as the first VLAN, and no VLAN tag is added to the data frames of the first VLAN. At the same time, data frames of the first VLAN and the second VLAN are allowed to pass through, and no VLAN tag is added to the data frames of the second VLAN and the third VLAN.

[0013] Optionally, the redundant network includes a first redundant network and a second redundant network, and the uplink and downlink ports of the APL field switch are both configured with second VLAN rules; The second VLAN rule includes: the uplink port of the APL field switch simultaneously allows data frames from the first VLAN, the second VLAN, and the third VLAN to pass through simultaneously, and adds corresponding VLAN tags to the data frames from the first VLAN, the second VLAN, and the third VLAN; wherein, among the uplink ports of the APL field switch, the uplink port of the APL power switch connected to the first redundant network is configured as the second VLAN, and the uplink port of the APL power switch connected to the second redundant network is configured as the third VLAN; the downlink port of the APL field switch is configured as the first VLAN, and no VLAN tag is added to the data frames of the first VLAN, while allowing data frames from the first VLAN and the second VLAN to pass through simultaneously, and adding VLAN tags to both the data frames from the second VLAN and the third VLAN.

[0014] Secondly, embodiments of this application provide a communication method applied to the communication system described in any one of the first aspects, the method comprising: When the target APL field device sends an uplink redundant data packet to the target redundant network, the target APL field device sends the uplink redundant data packet to the corresponding APL field switch, and then sends the uplink redundant data packet to the first redundant network through the APL field switch and the corresponding APL power switch in sequence. And / or when the target redundant network sends downlink redundant data packets to the target APL field device, the downlink redundant data packets are sent to the corresponding APL power switch, and then sequentially sent to the target APL field device through the APL power switch and the corresponding APL field switch.

[0015] Thirdly, embodiments of this application also provide a computer storage medium for storing a computer program; when the computer program is executed, it is used to perform the method described in any of the second aspects.

[0016] Fourthly, embodiments of this application also provide a computer program product containing instructions that, when the computer program product is run on at least one computing device, cause the at least one computing device to perform the method as described in any of the second aspects.

[0017] Fifthly, embodiments of this application provide an electronic device, including a processor and a memory; The memory is used to store computer programs; The processor is configured to perform the method as described in any of the second aspects based on the computer program.

[0018] Beneficial effects: This application provides a communication system and method. The communication system includes an access layer consisting of N1 identical APL power switches (with identical hardware and software) and an aggregation layer consisting of N2 cascaded APL field switches. In this aggregation layer, the first field switch establishes APL Ethernet connections with the downlink ports of different APL power switches, and N3 field devices are used to access the downlink ports of the target field switch. This communication system achieves independent access to the upper-layer redundant network through non-APL Ethernet and unifies the physical connection standards of the lower-layer devices through end-to-end APL Ethernet. Therefore, the system can distinguish between direct network data and isolated network data at the power switch layer using IGMP, and forward or send the two types of network data to the field switches separately through non-APL Ethernet, such as VLANs. This achieves a heterogeneous network where direct and isolated networks do not interfere with each other, meaning that a single communication system can simultaneously support both isolated and direct networks. Attached Figure Description

[0019] Figure 1 This application provides a schematic diagram of the structure of a communication system according to an embodiment of the present application. Figure 2 This is a schematic diagram of the structure of another communication system provided in an embodiment of this application; Figure 3 A schematic diagram illustrating the carrying of VLAN tags in communication data, provided as an embodiment of this application; Figure 4 A schematic diagram illustrating another communication data carrying a VLAN tag, provided as an embodiment of this application; Figure 5 This is a flowchart of a communication method provided in an embodiment of this application. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. The terminology used in the following embodiments is for the purpose of describing specific embodiments only and is not intended to be a limitation of this application. As used in the specification and appended claims of this application, the singular expressions "a," "an," "the," "the," "the," and "this" are intended to also include expressions such as "one or more," unless the context clearly indicates otherwise.

[0021] It should also be understood that in the embodiments of this application, "one or more" refers to one, two, or more; "and / or" describes the correspondence between associated objects, indicating that three relationships can exist; for example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following associated objects have an "or" relationship.

[0022] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0023] The "multiple" mentioned in the embodiments of this application refers to two or more. It should be noted that in the description of the embodiments of this application, terms such as "first" and "second" are used only for the purpose of distinguishing descriptions and should not be construed as indicating or implying relative importance, nor should they be construed as indicating or implying order.

[0024] This application provides a communication system that can simultaneously support redundant and isolated networks. The following detailed description, in conjunction with the accompanying drawings, provides a detailed explanation of the communication system provided in this application. It should be noted that the communication system serves as the communication carrier for a distributed industrial control system, and is used to connect the upper-level redundant network and APL field devices.

[0025] Appendix Figure 1 This is a schematic diagram of the structure of a communication system provided in an embodiment of this application.

[0026] like Figure 1 As shown, the communication system 100 includes at least a two-layer device cascade structure.

[0027] The first layer, also known as the heterogeneous network access layer, consists of N1 APL power switches. Each APL power switch has identical hardware and software configurations, and each APL power switch is used to independently access its corresponding redundant network via a non-APL Ethernet connection. N1 is an even number. For ease of explanation, see the appendix. Figure 1 Taking N2 as an example, the first layer includes two APL power switches: APL power switch 1 is connected to redundant network A, and APL power switch 2 is connected to redundant network B.

[0028] It should be noted that in this embodiment, different APL power switches can be connected to different redundant networks or to the same redundant network; this embodiment is not limited to this. A pair of redundant power switches need to be connected to the same network, which can contain one or at least two different redundant network data.

[0029] The second layer, also known as the heterogeneous network aggregation layer, consists of N2 APL field switches cascaded via APL Ethernet. In this cascaded layer, one uplink port of the first APL field switch is connected via APL Ethernet to the downlink port of the first power switch among the N1 APL power switches; similarly, one uplink port of the last APL field switch is connected via APL Ethernet to the downlink port of the second power switch among the N1 APL power switches. N2 is an integer greater than 1. For example, see attached... Figure 1 The diagram shows that one uplink port of APL Field Switch 1 (the first APL Field Switch) is connected to one downlink port of APL Power Switch 1, another uplink port is connected to one uplink port of APL Field Switch 2, one uplink port of APL Field Switch 2 is connected to one uplink port of APL Field Switch 3, and so on, until one uplink port of APL Field Switch N2-1 is connected to one uplink port of APL Field Switch N2 (the last APL Field Switch), and one uplink port of APL Field Switch N2 is connected to one downlink port of APL Power Switch 2.

[0030] The downlink ports of the APL field switches are used to connect N3 APL field devices via APL Ethernet, where N3 is a positive integer. It should be noted that one or more APL field switches can be selected from the N2 APL field switches as target APL field switches, and the downlink ports of the target APL field switches can be connected to the N3 APL field devices. For clarity, see the appendix. Figure 1 Taking N3 as an example, with APL field switch 1 as the target APL field switch, its three downlink ports are connected to three APL field devices via APL Ethernet.

[0031] Furthermore, the communication system 100 may also include a three-layer device cascade structure. (See appendix) Figure 2 This is a schematic diagram of another communication system provided in an embodiment of this application. For example... Figure 2 As shown, the communication system 100 also includes a third layer, also known as the APL field device layer, which includes N3 APL field devices for transmitting control network data.

[0032] In summary, this application provides a communication system comprising an access layer consisting of N1 identical APL power switches (both hardware and software) and an aggregation layer consisting of N2 cascaded APL field switches. In this aggregation layer, the first field switch establishes APL Ethernet connections with the downlink ports of different APL power switches, and the N3 field devices are used to access the downlink ports of the target field switch. This communication system achieves independent access to the upper-layer redundant network through non-APL Ethernet and unifies the physical connection standards of the lower-layer devices through end-to-end APL Ethernet. Thus, the system can distinguish between direct network data and isolated network data at the power switch layer using IGMP, and forward or send the two types of network data to the field switches separately through non-APL Ethernet, such as VLANs. This achieves a heterogeneous network where direct and isolated networks do not interfere with each other, meaning that a single communication system can simultaneously support both isolated and direct networks.

[0033] Furthermore, targeting Figures 1-2 The communication system described above is also configured with corresponding transmission rules, which will be explained in detail below.

[0034] In one example, the communication system provided in this application embodiment also provides transmission rules for point-to-point networks, namely Layer 2 switching rules, to achieve fast forwarding.

[0035] Specifically, both the APL power switch and the APL field switch are configured with multicast MAC address forwarding tables. For any APL power switch and APL field switch in the communication system, and where the downlink port (hereinafter referred to as the target downlink port) of the APL power switch and the uplink port (hereinafter referred to as the target uplink port) of the APL field switch are connected, in this embodiment, the APL power switch is used to send uplink multicast data to the corresponding APL field switch through the target downlink port and the target uplink port, based on its own multicast MAC address forwarding table. The APL field switch is used to send downlink port data to the corresponding APL power switch through the target uplink port and the target downlink port, based on its own multicast MAC address forwarding table.

[0036] The multicast MAC address forwarding table is a core configuration entry for industrial Ethernet devices. In this embodiment, it refers to a mapping table between multicast MAC addresses and device physical ports. The table contains various types of multicast MAC addresses and their corresponding forwarding ports. When a device receives multicast data, it extracts the multicast MAC address from the data, matches it to the corresponding forwarding port in the table, and forwards the data only to that specified port, rather than flooding it to all ports. This ensures the targeted transmission of multicast data while reducing network bandwidth usage, thus helping to meet the high-speed, low-latency transmission requirements of point-to-point networks.

[0037] Furthermore, to reduce the impact of multicast data on lower-layer devices (devices connected to the downlink port), constraints can be imposed on the types of uplink and downlink data on the network. For any given device, downlink data transmitted to other devices through the downlink port uses unicast data, while uplink data transmitted to other devices through the uplink port uses multicast data. Therefore, only the downlink-to-uplink Layer 2 forwarding policy needs to be enabled, meaning that data received from its own downlink port is forwarded to its own uplink port.

[0038] Furthermore, the communication system also includes redundant network isolation rules to prevent redundant network data from being mixed up. Specifically, when an APL field device sends an uplink redundant data packet to the target redundant network, a VLAN tag of the target redundant network is added to the uplink redundant data packet. The tag remains in place during device forwarding to prevent mixing up. The VLAN tag is then removed upon forwarding to the target redundant network. When the target redundant network sends a downlink redundant data packet to the target APL field device, the target redundant network sends the downlink redundant data packet to the corresponding APL power switch. The corresponding APL power switch adds a VLAN tag to the downlink redundant data packet and forwards it to the corresponding APL field switch. After the corresponding APL field switch removes the VLAN tag, the downlink redundant data packet is sent to the target APL field device.

[0039] In another example, the communication system also includes a secure isolation network. Specifically, in this communication system, for the APL power switch and the APL field switch, the Layer 2 network flooding function for broadcast and multicast frames is disabled, fundamentally blocking uncontrolled broadcast and multicast frame forwarding across the network.

[0040] Furthermore, for unicast frames, devices can forward them according to their own multicast MAC address forwarding table, but in the initial state, the corresponding entries are missing. Intelligent unicast communication based on ARP spoofing can be established through the following steps: Step 1: The device listens for ARP requests sent from the upper or lower layer network. When an ARP request is a query from device A in the communication system to device B, it records the IP address and MAC address of device A. Simultaneously, the MAC address and source port of device A are recorded in its own multicast MAC address forwarding table.

[0041] Step 2: The device queries its local configuration to see if device A and device B are allowed access. If they are, and the device detects an ARP request from the upper-layer network, it sends an ARP request to the lower-layer network (the other network) to query device B. In one specific implementation, the source IP address and source MAC address fields in the ARP protocol of this request are set to the IP address and MAC address of device A.

[0042] Step 3: After receiving the ARP request, device B establishes a mapping relationship between device A's IP address and MAC address in its own ARP table, and forwards the request directly to device A's port through the records in its own multicast MAC address forwarding table, sending an ARP response packet to device A; and records device B's MAC address and source port in its own multicast MAC address forwarding table. Subsequently, point-to-point packets between device A and device B are transparently forwarded using the multicast MAC address forwarding table of the devices.

[0043] Furthermore, in the application embodiment, the device listening for ARP requests can join the multicast group to be forwarded via the IGMP protocol, receive or send redundant data of the multicast group, parse the data through the application layer proxy service of the communication system, and resend the parsed data through the specified downlink port.

[0044] In another example, for this communication system, port VLANs and VLAN access rules are configured at Layer 1 and Layer 2, respectively. In this embodiment, three VLANs are defined: a first VLAN, a second VLAN, and a third VLAN.

[0045] When the redundant network includes a first redundant network and a second redundant network, both the uplink and downlink ports of the APL power switch are configured with a first VLAN rule. The first VLAN rule includes: the uplink port of the APL power switch is configured as the first VLAN, and no VLAN tag is added to the data frames of the first VLAN; APL power switches connected to the first redundant network allow data frames of the second VLAN to pass through; APL power switches connected to the second redundant network allow data frames of the third VLAN to pass through, and no VLAN tag is added to either the second or third VLAN data frames. The downlink port of the APL power switch is configured as the first VLAN, and no VLAN tag is added to the data frames of the first VLAN. At the same time, data frames of the first VLAN and data frames of the second VLAN are allowed to pass through, and no VLAN tag is added to the data frames of the second VLAN and the third VLAN.

[0046] Optionally, both the uplink and downlink ports of the APL field switch are configured with a second VLAN rule. The second VLAN rule includes: the uplink port of the APL field switch simultaneously allows data frames from the first VLAN, the second VLAN, and the third VLAN to pass through simultaneously, and adds corresponding VLAN tags to the data frames from the first VLAN, the second VLAN, and the third VLAN; specifically, among the uplink ports of the APL field switch, the uplink port of the APL power switch connected to the first redundant network is configured as the second VLAN, and the uplink port of the APL power switch connected to the second redundant network is configured as the third VLAN; the downlink port of the APL field switch is configured as the first VLAN, and no VLAN tag is added to the data frames of the first VLAN, while simultaneously allowing data frames from the first VLAN and the second VLAN to pass through, and adding VLAN tags to both the data frames from the second VLAN and the third VLAN.

[0047] For example, targeting Figure 1 As shown, if the first VLAN is VLAN C, the second VLAN is VLAN A, and the third VLAN is VLAN B, then the first-layer device's uplink port VLAN is configured as VLAN_C and VLAN_C is not tagged. Devices connecting to redundant networks A or B allow VLAN_A or VLAN_B to pass through respectively, and neither is tagged.

[0048] The downlink port VLAN of the first-layer device is configured as VLAN_C and VLAN_C is not tagged. At the same time, VLAN_A and VLAN_B are allowed to pass through, and neither is tagged.

[0049] The uplink port of the second-layer device allows VLAN_A, VLAN_B and VLAN_C to pass through simultaneously, and all of them are tagged. The port VLAN connected to the redundant network A corresponding to the first-layer device is configured as VLAN_A, and the port VLAN on the other side is configured as VLAN_B.

[0050] The downlink port VLAN of the second-layer device is configured as VLAN_C and VLAN_C is not tagged. At the same time, VLAN_A and VLAN_B are allowed to pass through, and neither is tagged.

[0051] Example 1, such as Figure 3The diagram illustrates a redundant isolation network carrying VLAN tags according to an embodiment of this application. In this mode, VLAN_C is used as the common transmission tag, and all interactive data between redundant networks A and B is transmitted with or without a VLAN_C tag. On the upper-layer redundant network side, the data is in a VLAN-untagged state, representing the native data format of the redundant control network, and has not undergone tagging processing by this communication system. After being intercepted and parsed by the APL power switch, the data is transmitted untagged to the APL field switch, or forwarded by the APL switch with a VLAN_C tag to other cascaded APL field switches. In this network layer, communication data achieves complete isolation and forwarding. From the APL field switch to the APL field device segment: the data is restored to a VLAN-untagged state, adapting to the basic data reception requirements of the field devices and reducing the resource consumption of device tag parsing.

[0052] Example 2, such as Figure 4 The diagram illustrates another redundant direct-connect network carrying VLAN tags provided in this application embodiment. In this mode, VLAN_A and VLAN_B are used as redundant network tags to achieve physical data isolation between redundant network A and redundant network B. On the upper-layer redundant network side, the data is in a state without VLAN tags and is the native data format of the redundant control network, without undergoing tagging processing by this communication system. From the APL power switch to the APL field switch: data from redundant network A is transmitted with the VLAN_A tag, and data from redundant network B is transmitted with the VLAN_B tag. The two tags are independent, achieving strict logical isolation between the two redundant network data and avoiding network mixing issues at the tag level. From the APL field switch to the APL field device: data is restored to a state without VLAN tags to meet the basic data reception requirements of field devices. Simultaneously, when field devices transmit data back to the redundant network, they will add either the VLAN_A or VLAN_B tag according to the target network to ensure isolation.

[0053] In summary, the communication system provided in this application embodiment can achieve heterogeneous redundant network compatibility based on the APL physical layer, and can establish secure and reliable communication in heterogeneous networks while satisfying broadcast domain isolation.

[0054] Furthermore, embodiments of this application also provide a communication method using the above-described communication system. (Appendix) Figure 5 A flowchart of a communication method provided in this application embodiment is shown. The method includes the following steps: S610, when the target APL field device sends an uplink redundant data packet to the target redundant network, the target APL field device sends the uplink redundant data packet to the corresponding APL field switch, and then sends the uplink redundant data packet to the first redundant network through the APL field switch and the corresponding APL power switch in sequence.

[0055] Optionally, in S620, when the target redundant network sends downlink redundant data packets to the target APL field device, the downlink redundant data packets are sent to the corresponding APL power switch, and then sequentially sent to the target APL field device through the APL power switch and the corresponding APL field switch.

[0056] The specific implementation of the communication method is described above and will not be discussed further here.

[0057] In summary, this application provides a method for communication in a communication system comprising an access layer of N1 identical APL switches (both hardware and software) and an aggregation layer of N2 cascaded APL field switches. Each field switch in the aggregation layer establishes APL Ethernet connections with the downlink ports of different APL power switches, and N3 field devices connect to the downlink ports of the target field switch. This communication system achieves independent access to the upper-layer redundant network via non-APL Ethernet and unifies the physical connection standards of the lower-layer devices through end-to-end APL Ethernet. Thus, the system can distinguish between direct network data and isolated network data at the power switch layer using IGMP, and forward or send both types of network data to the field switches via non-APL Ethernet, such as VLANs. This achieves a heterogeneous network where direct and isolated networks do not interfere with each other, meaning that a single communication system can simultaneously support both isolated and direct networks.

[0058] According to the method provided in the embodiments of this application, this application also provides a computer program product, which includes: computer program code, which, when run on a computer, causes the computer to execute the various steps or processes performed in any of the foregoing method embodiments.

[0059] According to the method provided in the embodiments of this application, this application also provides a computer-readable storage medium storing program code, which, when run on a computer, causes the computer to execute the various steps or processes performed in any of the foregoing method embodiments.

[0060] The computer-readable storage medium may be the aforementioned volatile memory or non-volatile memory, or it may include both volatile memory and non-volatile memory.

[0061] In the embodiments of this application, the terms and English abbreviations are exemplary examples given for ease of description and should not be construed as limiting the application in any way. This application does not preclude the possibility of defining other terms that can achieve the same or similar functions in existing or future agreements.

[0062] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When these computer instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated.

[0063] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0064] It should be understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0065] In summary, the above description is merely a preferred embodiment of the technical solution of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A communication system, characterized in that, The communication system includes: N1 APL power switches, each with identical hardware and software configurations, and each APL power switch is used to independently access the corresponding redundant network via a non-APL Ethernet network, where N1 is an even number. N2 APL field switches are cascaded via APL Ethernet; wherein, among the cascaded APL field switches, one uplink port of the first APL field switch is connected to the downlink port of the first power switch among the N1 APL power switches via APL Ethernet, and one uplink port of the last APL field switch is connected to the downlink port of the second power switch among the N1 APL power switches via APL Ethernet, and N2 is an integer greater than 1; The downlink port of the APL field switch is used to connect N3 APL field devices via the APL Ethernet, where N3 is a positive integer.

2. The communication system according to claim 1, characterized in that, Both the APL power switch and the APL field switch are configured with multicast MAC address forwarding tables. The communication system includes a first device and a second device. The first device is the APL power switch, and the second device is the APL field switch that communicates with the APL power switch. The second device is used to send uplink multicast data to the uplink port corresponding to the first device through the corresponding downlink port according to the multicast MAC address forwarding table; The first device is used to send downlink unicast data to the corresponding downlink port of the second device through the corresponding uplink port, based on the multicast MAC address forwarding table.

3. The communication system according to claim 2, characterized in that, The APL power switch and the APL field switch are configured to receive data from their own downlink ports and forward it to their own uplink ports.

4. The communication system according to claim 1, characterized in that, The communication system is configured such that when the APL field device sends an uplink redundant data packet to the target redundant network, it adds a VLAN tag of the target redundant network to the uplink redundant data packet and performs an operation to remove the VLAN tag in the target redundant network. When the target redundant network sends the downlink redundant data packet to the target APL field device, the target redundant network sends the downlink redundant data packet to the corresponding APL power switch. The corresponding APL power switch adds the VLAN tag to the downlink redundant data packet and forwards it to the corresponding APL field switch. After the corresponding APL field switch removes the VLAN tag, it sends the downlink redundant data packet to the target APL field device.

5. The communication system according to claim 1, characterized in that, The communication system is configured to disable the Layer 2 network flooding function for both the APL power switch and the APL field switch.

6. The communication system according to claim 5, characterized in that, The communication system is configured such that, for any target device in the APL power switch and the APL field switch, the target device receives an ARP request sent by the upper or lower layer network of the target device. When the ARP request is an ARP request from a third device in the communication system to query the fourth device, the target device records the IP address and MAC address of the third device and records the MAC address and source port of the third device in the Layer 2 MAC address table. The target device queries its local configuration to see if the third and fourth devices allow cross-network communication. If cross-network communication is allowed, the target device sends an ARP request to the fourth device. Upon receiving the ARP request, the fourth device establishes a mapping relationship between the IP address and MAC address of the third device in its own ARP table, and forwards the request directly to the port of the third device through the record in the Layer 2 MAC address table, sending an ARP response packet to the third device. The fourth device's MAC address and source port are also recorded in the Layer 2 MAC address table.

7. The communication system according to claim 6, characterized in that, The target device joins the multicast group to be forwarded via the IGMP protocol, receives or sends redundant data from the multicast group, parses the data through the application layer proxy service of the communication system, and retransmits the parsed data through the specified downlink port.

8. The communication system according to claim 1, characterized in that, The redundant network includes a first redundant network and a second redundant network, and the uplink and downlink ports of the APL power switch are both configured with a first VLAN rule. The first VLAN rule includes: the uplink port of the APL power switch is configured as the first VLAN, and no VLAN tag is added to the data frames of the first VLAN; the APL power switch connected to the first redundant network allows the data frames of the second VLAN to pass through; the APL power switch connected to the second redundant network allows the data frames of the third VLAN to pass through, and no VLAN tag is added to the data frames of the second VLAN and the data frames of the third VLAN. The downlink port of the APL power switch is configured as the first VLAN, and no VLAN tag is added to the data frames of the first VLAN. At the same time, data frames of the first VLAN and the second VLAN are allowed to pass through, and no VLAN tag is added to the data frames of the second VLAN and the third VLAN.

9. The communication system according to claim 1 or 8, characterized in that, The redundant network includes a first redundant network and a second redundant network, and the uplink and downlink ports of the APL field switch are both configured with second VLAN rules. The second VLAN rule includes: the uplink port of the APL field switch simultaneously allows data frames from the first VLAN, the second VLAN, and the third VLAN to pass through simultaneously, and adds corresponding VLAN tags to the data frames from the first VLAN, the second VLAN, and the third VLAN; wherein, among the uplink ports of the APL field switch, the uplink port of the APL power switch connected to the first redundant network is configured as the second VLAN, and the uplink port of the APL power switch connected to the second redundant network is configured as the third VLAN; the downlink port of the APL field switch is configured as the first VLAN, and no VLAN tag is added to the data frames of the first VLAN, while allowing data frames from the first VLAN and the second VLAN to pass through simultaneously, and adding VLAN tags to both the data frames from the second VLAN and the third VLAN.

10. A communication method, characterized in that, Applied to the communication system according to any one of claims 1-9, characterized in that the method comprises: When the target APL field device sends an uplink redundant data packet to the target redundant network, the target APL field device sends the uplink redundant data packet to the corresponding APL field switch, and then sends the uplink redundant data packet to the first redundant network through the APL field switch and the corresponding APL power switch in sequence. And / or when the target redundant network sends downlink redundant data packets to the target APL field device, the downlink redundant data packets are sent to the corresponding APL power switch, and then sequentially sent to the target APL field device through the APL power switch and the corresponding APL field switch.

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