Multiplexed transmission system, multiplexed transmission method, relay device

Abstract

To provide a multiplex transmission method and a relay device that enjoy the effects of both conventional type L2 path redundancy technology and frame replication type redundancy technology.SOLUTION: When a frame is transmitted from a host H1 to a host H2 in a network in which bridges B1-B12 are arranged in the hosts H1, H2 and which is multiplexed into a regular path and standby paths 1, 2, a bridge B1 selects regular transfer-multiplex transfer in accordance with traffic settings. For the multiplex transfer case, a frame is replicated in accordance with the number of paths and redundancy information is added to the frame when transferred. The bridges B8, B12 remove redundancy information from the frame transferred to the regular path and then transfers the frame to the H2. The bridges B7, B11 remove redundancy information from the frame transferred to the standby paths 1, 2 and then encapsulate the frame so as to be transparent to BLK 1, 2, with the frame decapsulated by the bridges B8, B12 and transferred to the host H2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to multiplexing control of a transmission path.

Background Art

[0002] (1) For example, STP (Spanning Tree Protocol) / RSTP (Rapid Spanning Tree Protocol) described in Non-Patent Documents 1 and 2 is called a conventional L2 (layer 2) redundancy path control technology. The conventional L2 redundancy path control technology extracts a loop on the network using some algorithm, and by prohibiting passage of at least one point on the loop, it logically maintains a state where there is no loop and prevents infinite looping of frames (and thereby congestion and communication failures).

[0003] Here, the group of paths contributing to communication in this state is defined as the "normal system" for convenience. As long as the normal system is healthy, only one path contributing to communication is always provided between any two points on the network (network).

[0004] If a path failure occurs in a part of the normal system and the communication path between two points is lost, the algorithm calculates a path based on the physical path configuration after the failure, re-evaluates the existence of the loop, and reviews the point to be blocked. As a result, if there is a path that bypasses the failure point, communication between the two points is restored when it is opened. The group of paths contributing to communication in this state is called the "standby system" for convenience.

[0005] Thus, the conventional L2 redundancy path control technology aims to make the "path" itself redundant (multiplexed) by appropriately switching between the normal system and the standby system. Note that the point blocked to eliminate the loop is denoted as a "Blocking Port" or simply "BLK Port". Also, the act of blocking is expressed as "to block".

[0006] (2) In addition, frame-replicating redundancy technology using PRP (Parallel Redundancy Protocol) / HSR (High-availability Seamless Redundancy), as described in Non-Patent Document 3, is also publicly known.

[0007] Frame duplication redundancy works by duplicating the frame to be transmitted and sending it through two (physically) different paths. As a result, if even one of the duplicated frames reaches its destination, no frame loss occurs from the perspective of the end hosts, even if all other frames are lost.

[0008] In contrast to conventional L2 redundant routing technology, frame duplication redundancy technology is characterized by its redundancy of frames, whereas conventional L2 redundant routing technology makes routes redundant. Furthermore, while conventional L2 redundant routing technology results in temporary transmission failures during route switching, frame duplication redundancy technology has the significant advantage that as long as one route is healthy, no frame loss occurs even if other routes experience failures.

[0009] Another method for making frames redundant is to detect frame loss at a higher layer and compensate by retransmitting it, as is done in TCP. However, with this method, redundant transmissions, i.e., retransmissions, travel along the same path, so they do not have the benefit of bypassing failures that occur along the path. [Prior art documents] [Non-patent literature]

[0010] [Non-Patent Document 1] "IT Terminology Dictionary: STP (Spanning Tree Protocol)" Internet, URL ≪https: / / e-words.jp / w / STP.html≫ [Non-Patent Document 2] "IT Terminology Dictionary: RSTP (Rapid Spanning Tree Protocol)" Internet, URL ≪https: / / e-words.jp / w / RSTP.html≫ [Non-Patent Document 3] "KMEXONE Co., Ltd. enhances reliability by rapidly restoring the network during failures" Internet, URL≪https: / / kmecsone.jp / article / moxa-column / column_15 / ≫ [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] (1) Problem 1 Conventional L2 redundancy routing technology works by blocking the passage of redundant paths on the network. On the other hand, using frame replication-based redundancy technology requires multiple physically distinct paths between end hosts.

[0012] These two methods are fundamentally incompatible in their structure. This is because the latter requires multiple paths between end hosts, while the former blocks all but one of the surplus paths.

[0013] (2) Problem 2 Using frame duplication redundancy techniques consumes twice the bandwidth of the original transmission rate because frames are duplicated and forwarded. Generally, path failures are not constant but occur sporadically.

[0014] Therefore, when viewed as a safeguard against path failures, frame-duplication type redundancy technology is overkill and could significantly increase the cost of capital investment. In particular, nowadays, there is an increase in bandwidth-intensive communication data such as video and audio (surveillance cameras, IP phones, etc.), and duplicating these without distinguishing between them can place an excessive burden on relay equipment and path cabling.

[0015] Therefore, in order to mitigate problem 2, the following measures can be considered. • For critical data (which generally uses less bandwidth), frame duplication-based redundancy technology ensures data transmission without loss. • For less critical data (generally using a large amount of bandwidth), fault tolerance is ensured using conventional path redundancy methods.

[0016] However, as mentioned above, conventional L2 path redundancy methods and frame replication-type redundancy technologies are fundamentally incompatible in their structure, and it is impossible to achieve the benefits of both without some kind of ingenuity.

[0017] (3) Problem 3 Frame duplication-based redundancy technology transmits duplicate frames via two paths, but this cannot be increased to three or more paths. Furthermore, it is not possible to selectively duplicate and transmit frames from multiple path candidates based on the type or importance of the frame being transmitted. To achieve these goals, a combination of the aforementioned methods would be the obvious solution, but this has not yet been realized.

[0018] This invention was made to solve the aforementioned problems of the conventional approach, and aims to enable the combined use of conventional L2 path redundancy technology and frame replication-type redundancy technology, thereby allowing users to enjoy the benefits of both technologies. [Means for solving the problem]

[0019] (1) One aspect of the present invention is that a group of relay devices is arranged between hosts, The connections between the aforementioned hosts are multiplexed into a primary path and a standby path by the relay device. Any of the relay devices located in the aforementioned standby path is equipped with a blocking port that is blocked by STP / RSTP, A method for controlling the multiplexing of the transmission path by using the blocking port as a relay point for the standby path, When a frame is transmitted from one of the hosts to the other host, the first relay device that is the route of both paths shall select normal transfer or multiplexed transfer by comparing the content of the frame with a pre-determined traffic class setting, when the multiplexed transfer is selected, duplicate the frame according to the number of paths, attach redundancy information to each frame, and transfer the frames to the normal path and the standby path respectively, the second relay device that is the end adjacent to the other host shall transfer the frame transferred to the normal path to the other host after removing the redundancy information, the third relay device that is the gateway to the blocking port shall encapsulate the frame transferred to the standby path so as to be transmissible through the blocking port after removing the redundancy information, the relay device having the blocking port is characterized by removing the encapsulation and transferring the frame.

[0020] (2) Another aspect of the present invention is that a group of relay devices is arranged between hosts, the hosts are multiplexed into a normal path and a standby path by the relay device, any one of the relay devices arranged in the standby path has a blocking port blocked by STP / RSTP, a method for controlling the multiplexing of the transmission path with the blocking port as a relay point of the standby path, when a frame is transmitted from one of the hosts to the other host, the first relay device that is the route of both paths selects normal transfer or multiplexed transfer by comparing the content of the frame with a pre-determined traffic class setting, when the multiplexed transfer is selected, duplicates the frame according to the number of paths, attaches redundancy information to each frame, and transfers the frames to the normal path and the standby path respectively, The second relay device, which is an end adjacent to the other host, forwards the frame that has been forwarded to the normal route to the other host after removing the redundancy information. The third relay device, which serves as a gateway to the blocking port, encapsulates the frame transferred to the standby path so that it can pass through the blocking port after removing the redundancy information. The relay device, which is equipped with the blocking port, is characterized by having the step of deencapsulating the frame and transferring it.

[0021] (3) Yet another aspect of the present invention is a relay device which constitutes a primary route and a standby route by arranging a plurality of them between hosts, Any of the devices located in the aforementioned standby path includes a blocking port that is blocked by STP / RSTP, When a frame is sent from one host to the other host, if it becomes the route for both paths, By comparing the contents of the aforementioned frame with a predetermined traffic class setting, normal forwarding or multiplexed forwarding is selected. If the aforementioned multiplexed transfer is selected, the frame is duplicated according to the number of paths, redundancy information is attached to each frame, and the frame is transferred to the primary path and the standby path, respectively. If the end is adjacent to the other host, the frame forwarded to the normal path is forwarded to the other host after the redundancy information is removed. When acting as a gateway to the blocking port, the frames forwarded to the standby path are encapsulated in a way that allows them to pass through the blocking port after the redundancy information has been removed. If the aforementioned blocking port is provided, the encapsulation is decapsulated and the frame is forwarded. [Effects of the Invention]

[0022] According to the present invention, by enabling the combined use of conventional L2 path redundancy technology and frame replication type redundancy technology, the benefits of both technologies can be enjoyed. [Brief explanation of the drawing]

[0023] [Figure 1] A diagram showing an example of a network according to an embodiment of the present invention. [Figure 2] Conceptual diagram of blocking ads. [Figure 3] Conceptual diagram of gateway advertising. [Figure 4] Internal diagram of the bridge. [Figure 5] A transition diagram showing frame tagging and encapsulation. [Figure 6] A simplified diagram of Figure 1. [Figure 7] A simplified diagram of triple redundant forwarding shown in Figure 1. [Figure 8] A simplified diagram of Figure 1 showing frame transfer on a commonly used route. [Figure 9] A simplified diagram of Figure 1 showing frame transfer in the standby path. [Figure 10] A simplified diagram of Figure 1 illustrating BPDU encapsulation transfer. [Figure 11] A simplified diagram of Figure 1 illustrating BPDU decapsulation in a blocking bridge. [Modes for carrying out the invention]

[0024] Embodiments of the present invention will be described below. Here, we propose a technology that combines means for ensuring route redundancy using conventional L2 routing protocols (e.g., STP "IEEE802.1D" or RSTP "IEEE802.1w") with means for transmission data redundancy by frame duplication using PRP / HSR (IEC62439-3).

[0025] In other words, by utilizing points blocked by conventional path redundancy technology (blocking ports) as relay points for redundant paths, and by encapsulating important frames in BPDU (Bridge Protocol Data Unit) to allow them to pass through blocking ports, selective redundant transmission is achieved.

[0026] <<Network Configuration Example>> An example of a network to which this embodiment is applied will be described based on Figure 1. Here, a redundant L2 bridge network is shown using conventional L2 path redundancy technology. However, the configuration in Figure 1 is merely an example shown for the sake of explanation, and can be implemented with any path configuration.

[0027] In Figure 1, H1 represents Host 1 and H2 represents Host 2, with a triple-redundant transmission path laid between H1 and H2. The relay devices that make up this transmission path are called "Bridge B". In Figure 1, a triple-redundant network is formed in the left-right direction by 12 bridges B1 to B12.

[0028] On the network, STP / RSTP is used to disconnect the closed loop, and in Figure 1, BLK1 and BLK2 of bridges B8 and B12 act as blocking ports. BLK1 and BLK2 resolve the closed loop on the network (if STP / RSTP were not used, an infinite loop of frames would occur on the closed loop, preventing healthy frame forwarding).

[0029] In Figure 1, the root bridge is positioned as bridge B1 in the upper left, but regardless of where the root is set, only the blocking port moves, and there is no essential impact.

[0030] The pentagonal boxes (CFG, BLK, GW) in Figure 1 represent messages transmitted between bridges B. These are all BPDUs (Bridge Protocol Data Units). A BPDU is an Ethernet frame with the destination address "MAC address 01:80:C2:00:00:00" and has the property of being able to pass through blocking ports.

[0031] Blocking ads / Gateway ads In this embodiment, since the blocking port is used as a relay point in a redundant path, the blocking port is advertised to the neighboring bridge B by blocking advertisement, and the transit points of the blocking port (hereinafter referred to as gateways / GW) are made known by gateway advertisement.

[0032] (1) First, let's briefly explain the blocking advertisement. In Figure 1, bridges B8 and B7, and bridges B12 and B11 are blocked by BLK1 and BLK2. BLK1 and BLK2 advertise to the adjacent bridges B7 and B11 that they are blocking ports. This advertisement is made by notifying bridges B7 and B11 from bridges B8 and B12 via BLK1 and BLK2.

[0033] In Figure 1, the two bridges B are shown in a one-to-one connection (point-to-point). However, in general, multiple bridges B may be connected to a blocking port. Therefore, Figure 2 shows such a typical connection.

[0034] Here, "Bridges B101, B102, ... B10x" are shown as gateways to BLK100. "B10x" means any number (it does not mean up to B109). In the case of Figure 2, BLK100 advertises to the neighboring bridges B101 to B10x that it is a blocking port.

[0035] (2) Next, we will explain the general outline of gateway advertising. For example, in Figure 3, bridge B101, located somewhere on the network, advertises to the network that it is a gateway (pass-through point / entry point) to a redundant path that includes blocking port BLK100 (blocking port BLK100 does not exist on bridge B101 at least).

[0036] Gateway ads are advertised on the network via Route Bridge B1. Detailed procedures for blocking ads and gateway ads will be described later.

[0037] <<Example of Bridge B configuration>> A configuration example of Bridge B will be explained based on Figure 4. In Figure 4, 1 represents Bridge B, which comprises a routing protocol 2, a frame forwarding redundancy processing unit 3, a BLK advertisement processing unit 4, a GW advertisement processing unit 5, a redundant routing database 6, and a traffic class setting unit 7.

[0038] Route control protocol 2 refers to existing routing protocols such as STP / RSTP. Furthermore, frame forwarding redundancy processing unit 3 is based on the existing PRP / HSR frame forwarding redundancy processing logic (Link Redundancy Entity: LRE), with the addition of a technology that combines the route redundancy assurance means of conventional L2 routing protocols with the transmission data redundancy means through frame replication.

[0039] The BLK advertising processing unit 4 represents the module that executes blocking advertisements. The GW advertising processing unit 5 represents the module that executes gateway advertisements. The redundant route database 6 represents a database for recording information obtained by executing gateway advertisements. Aging processing of the recorded information is also built into this database.

[0040] The traffic class setting unit 7 shows a database for recording setting values ​​that define the classification of frames to be forwarded. Here, the frame forwarding redundancy processing unit 3 refers to both 6 and 7 and performs frame forwarding processing as needed.

[0041] Note that 8 in Figure 4 represents the bridge network, which corresponds to the network portion composed of bridges B1 to B12 in Figure 1 / the bridge network in Figure 1, and communication occurs via end host 9.

[0042] <<Frame Dagging and Encapsulation>> Based on Figure 5, the process of adding redundancy information to a frame (dagging) and the subsequent encapsulation of that information will be explained.

[0043] (1) Original frame Figure 5(a) shows the structure of the original frame received when the bridge performs a forwarding operation. Figures 5(b) to 5(g) show the processed state of the original frame. Here, the original frame portion is shown in white, and the added fields are shown in shaded areas. Note that the FCS at the end of the frame is recalculated (mainly by hardware such as the switch engine) after the frame has been processed (addition or deletion of fields).

[0044] (2) After attaching redundancy information via PRP Figure 5(b) shows the original frame from Figure 5(a) after redundancy information has been added by PRP. The "RCT" (Redundancy Control (Check) Trailer) field in the figure represents the added information (6 octets).

[0045] (3) After attaching redundancy information via HSR Figure 5(c) shows the original frame from Figure 5(a) after redundancy information has been added by HSR. The "HSR TAG" field in the figure contains the added information (6 octets).

[0046] (4) After attaching redundancy information (in the case of PRP) Figure 5(d) shows the configuration of frames forwarded to the redundant path in this embodiment. In this figure, "DST_GW" indicates the "MAC address" of the gateway bridge (details will be described later).

[0047] Furthermore, "SRC_FH" indicates the MAC address of Bridge B, the first bridge (First Hop) to receive this frame from Host H and forward it; that is, the first bridge to duplicate the received frame, add redundancy information, and then forward it.

[0048] (5) After attaching redundancy information (in the case of HSR) Figure 5(e) is configured almost identically to Figure 5(d), differing in that the added redundancy information is configured as shown in Figure 5(c).

[0049] (6) BPDU encapsulation (in the case of PRP) The encapsulation shown in Figure 5(f) removes the "Ethernet header (destination MAC address, source MAC address, Ethernet frame type field)" and the "redundant route label LABEL" that follows it from the configuration shown in Figure 5(d), and instead adds the "BPDU encapsulation field" from Table 1 to the beginning of the frame.

[0050] [Table 1]

[0051] All fields in Table 1 have the same structure as a standard "CFG-BPDU," and by substituting the values ​​of the "Protocol ID" and "Type Field," it is indicated that the portion from offset 18 onwards is a unique frame format.

[0052] (7) BPDU encapsulation (in the case of HSR) The encapsulation in Figure 5(g) is configured almost identically to that in Figure 5(f), differing in that the added redundancy information is configured as shown in Figure 5(c).

[0053] ≪Explanation of Operation≫ The operation process of this embodiment will be described below. • Blocking ads Gateway advertising • Selective copying and transfer The operation process will be explained in three stages.

[0054] (1) Blocking ads A: First, let's discuss the necessity of blocking advertisements (procedures to notify nearby bridges of the existence of a blocking port). Extracting redundant paths from a network of any configuration and then forwarding frames along those redundant paths is generally not easy. MPLS (Multiprotocol Label Switching) is a well-known existing technology for doing this, but it is difficult to design routes and has difficulties in adapting to changes in the physical configuration.

[0055] When using STP / RSTP, the spanning tree algorithm can block a specific point in a cycle. In this embodiment, this location is used to extract redundant paths. Since the point blocking the cycle is clearly located somewhere on the redundant path, forwarding frames to pass through the blocking port will ensure they reach their destination via the redundant path. This method enables transmission via redundant paths without the need for complex network design like MPLS.

[0056] However, current STP / RSTP protocols do not have a procedure for advertising the location of blocking ports. In this embodiment, the existence of redundant paths is advertised on the network through a two-step procedure: "blocking advertisement" and "gateway advertisement".

[0057] In this case, with STP / RSTP, only bridge B, which has the blocking port, can detect the presence of the blocking port. Therefore, bridge B, which has the blocking port, notifies the adjacent bridge B connected via that port of the existence of the blocking port.

[0058] B: Next, the blocking advertisement procedure will be explained based on Figure 2. Here, port BLK100 of bridge B100 is blocked and has become a blocking port. Here, bridge B100 sends a blocking advertisement message (BLK in Figure 2) from blocking port BLK100 to neighboring bridges B101 to B10x.

[0059] This advertising message is a type of BPDU and can bypass the blocking port BLK100. This advertising message contains information such as the "Bridge ID, MAC address, and blocking port number" of bridge B100, which has the blocking port BLK100.

[0060] When an adjacent bridge "B101, B102, ... B10x" receives this advertisement message, it can detect that a blocking port BLK100 exists between it and the adjacent bridge B100.

[0061] In other words, adjacent bridges "B101, B102, ... B10x" can detect that they are part of a redundant path that includes the blocking port BLK100, and that they are located at its entry point. As a result, adjacent bridges "B101, B102, ... B10x" become aware of their role as gateways to the redundant path that includes port BLK100, and advertise themselves as gateways on the network. In this sense, bridge B adjacent to a blocking port can be called a gateway bridge.

[0062] (2) Gateway advertising Upon receiving the aforementioned blocking advertisement and realizing it is located at the entry point to a redundant path, the gateway bridge advertises this fact on the network. Specifically, it performs procedure (c) to link the two identifiers (a) and (b) shown below to create a redundant path identifier and share this with other bridges B on the network.

[0063] (a) Blocking identifier Since multiple blocking ports can exist on a network, a parameter is needed to uniquely identify each blocking port. This parameter is the blocking identifier, which consists of "bridge ID, MAC address, and port number." Generally, the MAC address is included in the bridge ID (the last 6 bytes are considered the MAC address), so it is also possible to represent it using only "bridge ID and port number."

[0064] (b) Gateway identifier The gateway identifier is information that identifies Bridge B, which acts as the entry point (gateway) when forwarding frames through a redundant path including a blocking port, and consists of "Bridge ID, MAC address". Generally, the MAC address is included in the Bridge ID (the last 6 bytes are considered the MAC address), so it is also possible to represent it using only the "Bridge ID".

[0065] (c) Sharing procedures Based on Figure 3, the gateway advertisement, i.e., the procedure for sharing redundant route identifiers, will be explained. Here, bridge B101 corresponds to the gateway bridge (GW100), and in order to advertise to all bridges on the network, it sends a gateway advertisement message (GW in Figure 3) containing the redundant route identifier to root bridge B1.

[0066] This message is a type of BPDU, sent to root bridge B1, and transported to root bridge B1 via a bucket brigade system using intermediate bridges located along the way. Upon receiving this message, root bridge B1 registers the redundant route identifier in its redundant route database 6.

[0067] Furthermore, Route Bridge B1 adds an extension field to the "CFG-BPDU (Configuration BPDU)" that it broadcasts to the network during each hello time, attaching the currently valid redundant route identifier before transmitting it.

[0068] At this time, the "CFG-BPDU" transmitted by root bridge B1 is received by all bridges B on the network except for root bridge B1 itself (this is a function of the existing STP / RSTP technology). Each bridge B that receives the "CFG-BPDU" performs the standard STP / RSTP route calculation process based on it and registers the redundant route identifier attached to the end of the message in its redundant route database 6.

[0069] This mechanism for advertising information on the network via the root bridge B1 is the same as "TCN-BPDU" in STP. Because "CFG-BPDU" is very short, a considerable number of redundant route identifiers can be appended to the end. However, if it exceeds the MTU (Maximum Frame Length: generally 1518 bytes), fragment transmission can be easily achieved by sending the excess portion in the next "CFG-BPDU".

[0070] (3) Selective copying and transfer The frame forwarding redundancy processing unit 3 forwards frames while referring to the redundant route database 6 constructed by "gateway advertisement" and the pre-configured traffic class setting unit 7. Based on the configuration example in Figure 1, the redundant route database 6 for each bridge B1 to B12 is constructed by gateway advertisement to the contents shown in Table 2.

[0071] [Table 2]

[0072] In Table 2, the "Blocking Identifier" column lists the combination of "ID of Bridge B with the blocking port:blocking port number". Additionally, the "Gateway Identifier" column in Table 2 lists "ID of Bridge B, which serves as the entry point for traffic passing through the blocking port."

[0073] Furthermore, the "Redundant Route Label" value on the far left of Table 2 indicates the identification number assigned to each entry in the redundant route database 6. This value is uniquely determined in root bridge B1 and will not change during operation unless aged out.

[0074] To explain in detail based on Figure 6, blocking port BLK1 exists on bridge B8, and blocking port BLK2 exists on bridge B12. Bridges B8 and B12 perform blocking advertisements via blocking ports BLK1 and BLK2, respectively. Figures 6 to 9 show simplified diagrams of Figure 1, where N represents the primary system path and W1 and W2 represent the standby system paths 1 and 2.

[0075] Here, bridges B7 and B11, adjacent to bridges B8 and B12, recognize themselves as gateways based on this message and advertise this via root bridge B1. As a result of this redundant route information spreading across the network, entries like those in Table 2 are formed in the redundant route database 6. The value of the redundant route label is determined by factors such as the order in which the advertisements arrive at the root bridge, and the actual assigned value is a matter of chance (only uniqueness is guaranteed).

[0076] Table 3 shows an example of the settings for the traffic class setting unit 7 in the configuration example shown in Figure 1. The contents of this table are just one example, and various forms of traffic definitions and actions are conceivable.

[0077] [Table 3]

[0078] When the traffic class setting unit 7 is in the state shown in Table 3, the following processing steps (S01 to S03) are executed when the root bridge B1 receives a frame from host H1.

[0079] S01: The contents of the frame are queried to the traffic class setting unit 7 and evaluated to determine which definition it corresponds to.

[0080] S02: The frame is forwarded according to the "action" specified in the appropriate traffic class. The subsequent processing is described below, categorized by the type of action.

[0081] S02-1: Normal Transfer If the frame received from host H1 matches traffic class 1 (or does not match any user-defined class), the action instructed by the traffic class setting unit 7 is "normal forwarding".

[0082] This action forwards received frames only to the primary route without redundancy. In this forwarding mode, frames are forwarded without attaching redundancy information (RCT for PRP, HSR tag for HSR).

[0083] S02-2: Redundant Transfer If a frame received from host H1 matches traffic class 2, the traffic class setting unit 7 will perform "redundant forwarding" as the specified action.

[0084] At this time, one copy of the received frame is made (totaling two frames including the original frame), and each is transmitted one by one through the primary route and one through the standby route 1 (S02-2-1, S02-2-2).

[0085] S02-2-1: Transmission from the regular route When transmitting from the primary transmission route, redundancy information must be attached according to the PRP / HSR specifications. Specifically, an RCT tag must be attached for PRP, and an HSR tag for HSR (see Figures 5(b) and 5(c)).

[0086] S02-2-2: Transmission from standby route 1 Even when transmitting from standby path 1, redundancy information is first attached according to the PRP / HSR specifications. Specifically, an RCT tag is attached for PRP, and an HSR tag for HSR. This frame is then encapsulated by adding the Ethernet header shown in Table 4 to the beginning of the frame. After this encapsulation, the data structure becomes as shown in Figures 5(d) and 5(e).

[0087] [Table 4]

[0088] S02-3: Triple-redundant forwarding If a frame received from host H1 conforms to traffic class 3, the traffic class setting unit 7 will execute "triple redundant forwarding" as the action instructed.

[0089] In this case, redundant forwarding is performed, similar to S02-2. However, it differs from S02-2 in that transmission is also performed from the standby path 2. This results in triple frame redundancy (see Figure 7), further increasing the reliability of arrival.

[0090] S03: After frame transfer S03-1: In the case of a regularly used route Frames discharged (forwarded) onto the primary path are forwarded to their destination via normal Ethernet switch forwarding. If redundancy information from PRP / HSR is attached, the redundancy information is removed by the final bridge B12 (end hop), as shown in Figure 8. This is the operation specified in PRP / HSR.

[0091] S03-2: In the case of a standby route As mentioned above, frames sent (forwarded) to the standby path are encapsulated, and the destination MAC address is the MAC address of gateway bridges B7 and B11.

[0092] Therefore, as shown in Figure 9, this frame is sequentially forwarded to gateway bridge B7 or B11 via Ethernet switch forwarding. Gateway bridges B7 and B11, upon receiving this frame, execute the following steps (S03-2-1 to S03-2-8).

[0093] S03-2-1: Type Determination The value of the Ethernet frame type field is referenced, and if the value matches the type assigned to the protocol of this embodiment, it can be identified as an encapsulated frame, and the process proceeds to S03-2-2. Otherwise, the normal Ethernet frame reception process is performed.

[0094] S03-2-2: Obtaining redundant path labels The value of the 4-octet LABEL field, which follows the Ethernet frame type field of the frame, is referenced and retrieved. At this time, since the redundant routing database 6 shown in Table 2 is configured, the label of the frame sent to bridge B7 must be "1", and the label of the frame sent to bridge 11 must be "2".

[0095] S03-2-3: Matching redundant path labels The label value retrieved in S03-2-2 is compared with the redundant routing database 6 to retrieve an entry. If an entry cannot be retrieved (or if the label does not correspond to a gateway), the frame is discarded and processing is terminated.

[0096] S03-2-4: Determining the forwarding destination If an entry in the redundant routing database 6 is successfully retrieved, the value in the "Blocking Identifier" field of that entry is referenced to search for the adjacent bridge B that is the destination for forwarding.

[0097] Here, Bridge B7 retrieves the entry corresponding to label 1 from the redundant routing database in Table 2 and recognizes that the destination is Bridge B8. Similarly, Bridge B11 retrieves the entry corresponding to label 2 from the redundant routing database in Table 2 and recognizes that the destination is Bridge B12.

[0098] S03-2-5: BPDU encapsulation Bridges B7 and B11 remove the Ethernet header (destination MAC address, source MAC address, Ethernet frame type field) and the 4-octet redundant route label LABEL from the received frame. Then, they write a value to the type field shown in Table 1 and perform BPDU encapsulation. After this encapsulation, the data structure becomes as shown in Figures 5(f) and 5(g).

[0099] S03-2-6: Blocking Bridge Transfer Bridges B7 and B11 forward the BPDU-encapsulated frames in S03-2-5 to adjacent bridges B8 and B12, as shown in Figure 10.

[0100] S03-2-7: BPDU encapsulation decapsulation Since a BPDU-encapsulated frame is a type of BPDU, it passes through BKL1 and BKL2, as shown in Figure 11, and reaches bridges B8 and B12. At this point, bridges B8 and B12 deencapsulate the received frame.

[0101] In other words, the BPDU encapsulation field at the beginning of the frame is removed before forwarding. When performing this forwarding, the destination MAC address of the frame is compared against the proxy node table of the frame forwarding redundancy processing unit 3. If the matching results in no hit, the data is discharged to the normal network path. If a hit is found in the proxy node table, the data is passed directly to its own frame forwarding redundancy processing unit 3, and it is not discharged to the normal network path.

[0102] S03-2-8: Transfer to Frame Transfer Redundancy Processing Unit 3 The frame, decapsulated at bridge B8, travels through the regular network path to bridge B12. Since this is already a normal Ethernet frame, it is received and processed according to the usual rules.

[0103] In other words, the frame forwarding redundancy processing unit 3 of bridge B12 removes the RCT before forwarding it to host H2 (or, if a duplicate frame from another path has already passed through, the frame is discarded without being forwarded). This is the standard procedure for PRP / HSR.

[0104] Frames that have traveled through standby path 2 are decapsulated by BPDU encapsulation in bridge B12 and then directly passed to bridge B12's frame forwarding redundancy processing unit 3, which is also similarly entrusted to PRP / HSR processing.

[0105] According to this embodiment, conventional redundant routing technologies (such as STP / RSTP) and frame replication-type redundancy technologies (PRP / HSR) can be used in combination, and the benefits of both technologies can be enjoyed.

[0106] In other words, by replicating and forwarding high-priority traffic with low bandwidth usage using PRP / HSR, frame loss in the event of a path failure can be suppressed, while low-priority traffic that wastes bandwidth can be made fault-tolerant using conventional routing technologies.

[0107] Furthermore, while PRP / HSR only allows for redundancy, this invention offers the advantage of supporting triple redundancy or higher. In addition, it is possible to switch the redundant path used for each traffic class, thereby contributing to load balancing of communication paths.

[0108] It should be noted that the present invention is not limited to the embodiments described above, and can be implemented with modifications within the scope of each claim. For example, the configuration of bridge B is not limited to Figure 4, but may be made to function with any configuration. Furthermore, there are no particular limits to the multiplexing of the route configuration, and quadruple or more redundancy is possible. In addition, depending on the settings of the traffic class setting unit 7, it is also possible to switch the route used for redundant forwarding for each traffic class. [Explanation of Symbols]

[0109] 1…Bridge B (B1~B12, B21, B22, B101~B10x) 2…Routing protocol 3…Frame Transfer Redundancy Processing Unit (LRE) 4…BLK Advertising Processing Unit 5…GW Advertising Processing Department 6…Redundant routing database 7…Traffic class setting section 8…Bridge Network 9…Host H (H1, H2...)

Claims

1. A group of relay devices is placed between the hosts. The transmission paths between the aforementioned hosts are multiplexed into a primary path and a standby path by the relay device. Any of the relay devices arranged in the standby path are equipped with a blocking port that is blocked by STP / RSTP, A method for controlling the multiplexing of the transmission path by using the blocking port as a relay point for the standby path, When a frame is transmitted from one host to the other, the first relay device, which acts as the root bridge between the primary path and the standby path, By comparing the contents of the aforementioned frame with a predetermined traffic class setting, normal forwarding or multiplexed forwarding is selected. When the multiplexed transfer is selected, the frame is duplicated according to the number of paths in the primary path and the standby path, redundancy information is attached to each duplicated frame, and the frame is transferred to the primary path and the standby path, respectively. The second relay device, which is an end adjacent to the other host, forwards the frame transferred to the normal path to the other host after removing the redundancy information. The third relay device, which serves as a gateway to the blocking port, encapsulates the frame transferred to the standby path so that it can pass through the blocking port after removing the redundancy information, and transfers the encapsulated frame to the blocking port provided by the second relay device. The second relay device, upon receiving the encapsulated frame at the blocking port, decapsulates the frame and forwards it to the other host. A multiplexed transmission method characterized by the following:

2. The second relay device, which includes the blocking port, The information of the blocking port is transmitted to the third relay device in a transparent encapsulation of the blocking port, The third relay device, having received the encapsulated information, transmits a message containing a redundant route identifier, including the identifier of the blocking port and its own gateway identifier, to the first relay device. The multiplexed transmission method according to claim 1, characterized in that it is described in the present invention.

3. Upon receiving the message, the first relay device registers the redundant route identifier in its own database and transmits the currently valid redundant route identifier to the other relay devices, Each relay device that receives the aforementioned transmission registers the redundant route identifier in its own database and refers to it to identify the destination of the frame that has been forwarded to the standby route. The multiplexed transmission method according to claim 2, characterized in that it is described in the present invention.

4. The third relay device encapsulates the data in a BPDU (Bridge Protocol Data Unit) and allows it to pass through the blocking port. The multiplexed transmission method according to claim 1, characterized in that it is described in the present invention.

5. The first relay device determines the number of copies of the frame according to the traffic class, The multiplexing transmission method according to any one of claims 1 to 4, characterized in that it is capable of transmitting the aforementioned frames in triple or greater redundancy.

6. The first relay device is capable of selecting a standby path according to the traffic class, characterized in that the multiplexed transmission method according to any one of claims 1 to 4.

7. A group of relay devices is placed between the hosts. The transmission paths between the aforementioned hosts are multiplexed into a primary path and a standby path by the relay device. Any of the relay devices arranged in the standby path are equipped with a blocking port that is blocked by STP / RSTP, A method for controlling the multiplexing of the transmission path using the blocking port as a relay point for the standby path, When a frame is transmitted from one host to the other, the first relay device, which acts as the root bridge between the primary path and the standby path, The steps include selecting normal forwarding or multiplexed forwarding by comparing the contents of the frame with a predetermined traffic class setting, When the aforementioned multiplexed transfer is selected, the frame is duplicated according to the number of routes in the primary route and the standby route, redundancy information is attached to each duplicated frame, and the frame is transferred to the primary route and the standby route, respectively. The second relay device, which is an end adjacent to the other host, forwards the frame that has been forwarded to the normal route to the other host after removing the redundancy information. The third relay device, which serves as a gateway to the blocking port, encapsulates the frame transferred to the standby path so that it can pass through the blocking port after removing the redundancy information, and transfers the encapsulated frame to the blocking port provided by the second relay device. The second relay device, which is equipped with the blocking port, decapsulates the encapsulated frame when it receives the encapsulated frame at the blocking port and forwards the frame to the other host. A multiplexed transmission method characterized by having the following features.

8. A relay device that multiplexes the transmission path into a primary path and a standby path by placing multiple units between hosts, Any of the devices located in the aforementioned standby path includes a blocking port that is blocked by STP / RSTP. When a frame is transmitted from one host to the other host, if it becomes a root bridge between the primary path and the standby path, By comparing the contents of the aforementioned frame with a predetermined traffic class setting, normal forwarding or multiplexed forwarding is selected. If the aforementioned multiplexed transfer is selected, the frame is duplicated according to the number of paths between the primary system path and the standby system path, redundancy information is attached to each duplicated frame, and the frame is transferred to the primary system path and the standby system path, respectively. If the end is adjacent to the other host, the frame forwarded to the normal path is forwarded to the other host after the redundancy information is removed. When acting as a gateway to the blocking port, the frame forwarded to the standby path is encapsulated in a way that allows it to pass through the blocking port after the redundancy information has been removed, and the encapsulated frame is forwarded to the blocking port provided by the end. If an end receives the encapsulated frame at the blocking port, it deencapsulates the frame and forwards it to the other host. A relay device characterized by the following features.

9. In the case of the end having the blocking port, The information of the blocking port is transmitted to the gateway in a transparent encapsulation of the blocking port, Upon receiving the encapsulated information, the gateway sends a message containing a redundant route identifier, including the identifier of the blocking port and its own gateway identifier, to the route. The relay device according to claim 8, characterized in that it is a relay device.

10. The aforementioned root bridge registers the redundant route identifier in its own database and transmits the currently valid redundant route identifier to other relay devices, Each relay device that receives the aforementioned transmission registers the redundant route identifier in its own database and refers to it to identify the destination of the frame that has been forwarded to the standby route. The relay device according to claim 9.

11. The gateway encapsulates the data in a BPDU (Bridge Protocol Data Unit) and allows it to pass through the blocking port. The relay device according to claim 8, characterized in that it is a relay device.

12. The root bridge determines the number of copies of the frame according to the traffic class, The relay device according to any one of claims 8 to 11, characterized in that it is capable of transmitting the aforementioned frames in triple or greater redundancy.

13. The relay device according to any one of claims 8 to 11, characterized in that the route bridge can select a standby route according to the traffic class.

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