Network system

Abstract

This network system comprises: a network failure information management unit that manages information about failure locations of a first ETB and a second ETB; a VLAN setting unit; a routing setting unit; a transfer function unit; and a frame rewriting function unit that rewrites the destination of a frame determined by the transfer function unit to be a frame addressed to the failure locations. When a failure occurs in the second ETB, the VLAN setting unit sets a bypass VLAN between an ECN of the configuration of a preceding stage of a location where the failure occurs, an ECN of the configuration of a subsequent stage of the location where the failure occurs, and a first ETB between the configuration of the preceding stage and the configuration of the subsequent stage. The routing setting unit: rewrites, to a routing entry addressed to the first ETBN, a routing entry addressed to an ETBN of the configuration of the subsequent stage of the location where the failure occurs; routes, according to the rewritten routing entry, a frame of which the destination has been rewritten by a frame rewriting function unit; and transmits the frame via the bypass VLAN.

Description

Network system

[0001] The present disclosure relates to a network system.

[0002] Devices such as a propulsion control device and a brake device provided in a train composed of at least one or more formations communicate with other in-train devices within the formation or between formations. Therefore, a network system is formed within and between formations by a train control and management system (TCMS: Train Control and Management System) or the like.

[0003] In the network system, when a failure occurs in the network, in order to continue communication, a plurality of paths are provided in advance, and the path used for communication is switched when a failure occurs. For example, in the communication network, relay node, and communication path switching method of Patent Document 1, according to the state of the ring network, by switching the failure recovery operation of link aggregation, it is possible to switch the path in the case of a single failure and maintain communication even in the case of multiple failures. A communication network, relay node, and path switching method are disclosed.

[0004] Japanese Patent Application Laid-Open No. 2013-197833

[0005] On the other hand, the in-train network system is composed of an ECN (Ethernet (registered trademark) Consist Network), which is a network used for in-formation communication, and an ETB (Ethernet Train Backbone), which is a network used for between-formation communication.

[0006] The ECN is composed of a device that is the source of communication, a device that is the destination of communication, a cable or relay device that connects between devices, etc. At least one ECN is provided within a formation.

[0007] The ETB is composed of an ETBN (Ethernet Train Backbone Node), a cable or relay device that connects between devices, etc. At least two ETBNs are provided within a formation. The ETBNs within a formation are connected to the ETBNs of other formations by a cable or the like to form an ETB. At least two ETBs are provided in the train.

[0008] Each ECN, of which at least one is provided within the trainset, is separately connected by different cables to two ETBNs within the trainset, each belonging to a different ETB.

[0009] When a device within one ECN configuration communicates with a device within another ECN configuration, the same data is transmitted via different ETBs.

[0010] However, there was a problem in that if an ETB (Enterprise Time Board) failure occurred in the network system, inter-train communication could not be maintained at the affected ETB.

[0011] This disclosure was made to solve the problems described above, and aims to provide a network system that can continue inter-training communication even if an ETB fails.

[0012] The network system relating to this disclosure is a network system comprising: a first ETBN provided within a train set and used for communication between train sets, a second ETBN provided within a train set and used for communication between train sets, a first ETB formed by connecting the first ETBNs provided in each train set to each other, a second ETB formed by connecting the second ETBNs provided in each train set to each other, and an ECN provided within a train set and separately connected to the first ETBN and the second ETBN, which performs inter-train set broadcast IP (Internet Protocol) communication using the first ETB and the second ETB. The network system comprises a network failure information management unit that manages information on failure locations in the first ETB and the second ETB; a VLAN setting unit that sets up a VLAN (Virtual Local Area Network) in either the first ETB, the second ETB, or the ECN; a routing setting unit that sets up routing entries for the first ETBN and the second ETBN; a forwarding function unit that, upon receiving a frame, determines whether the frame is destined for a failure location managed by the network failure information management unit; and a frame rewriting function unit that rewrites the destination of a frame for which the forwarding function unit has determined the frame is destined for a failure location. If a failure occurs in the second ETB, the VLAN configuration unit configures a bypass VLAN between the ECN of the preceding configuration at the location of the failure, the ECN of the following configuration at the location of the failure, and the first ETB between the preceding and following configurations. The routing configuration unit then rewrites the routing entry destined for the ETBN of the following configuration at the location of the failure to a routing entry destined for the first ETBN. The frame rewriting function unit routes the frame whose destination has been rewritten using the rewritten routing entry and transmits it via the bypass VLAN.

[0013] According to the network system described in this disclosure, even if an ETB failure occurs, inter-train communication can continue at the ETB that experienced the failure.

[0014] This is a schematic diagram showing the configuration of the network system according to Embodiment 1 of this disclosure. This is a schematic diagram showing a failure in the configuration of the network system according to Embodiment 1 of this disclosure. This is a configuration diagram showing the ETBN of the network system according to Embodiment 1 of this disclosure. This is a diagram showing the R-NAT table of the network system according to Embodiment 1 of this disclosure. This is a diagram showing the routing table of the network system according to Embodiment 1 of this disclosure. This is a diagram showing the FDB of the network system according to Embodiment 1 of this disclosure. This is a diagram showing the ETB link status table of the network system according to Embodiment 1 of this disclosure. This is a diagram showing the VLAN table of the network system according to Embodiment 1 of this disclosure. This is a diagram showing the occurrence of a failure in the network system according to Embodiment 1 of this disclosure. This is a diagram showing the detour operation when a failure occurs in the network system according to Embodiment 1 of this disclosure. This is a diagram showing the VID setting operation for detour in the network system according to Embodiment 1 of this disclosure. This is a diagram showing the detour operation when a failure occurs in the network system according to Embodiment 1 of this disclosure. This is a flowchart showing the detour operation (ETBN setting change) when a failure occurs in the network system according to Embodiment 1 of this disclosure. This is a flowchart showing the detour operation (ETBN data processing) when a failure occurs in the network system according to Embodiment 1 of this disclosure. This is a diagram showing fault recovery in a network system according to Embodiment 2 of this disclosure. This is a flowchart showing the operation (ETBN data processing) during fault recovery in a network system according to Embodiment 2 of this disclosure. This is a diagram schematically showing the configuration of a network system according to Embodiment 3 of this disclosure. This is a diagram schematically showing a fault in the configuration of a network system according to Embodiment 3 of this disclosure. This is a configuration diagram showing the ETBN of a network system according to Embodiment 3 of this disclosure. This is a diagram showing the detour operation when a fault occurs in a network system according to Embodiment 3 of this disclosure. This is a diagram showing the VID setting operation for detour in a network system according to Embodiment 3 of this disclosure. This is a diagram showing the detour operation when a fault occurs in a network system according to Embodiment 3 of this disclosure.This figure shows the status table of the opposite ETBN direct connection port of the network system according to Embodiment 4 of this disclosure. This figure shows the detour operation in the event of a failure in the network system according to Embodiment 4 of this disclosure. This figure shows the VID setting operation for detour in the network system according to Embodiment 4 of this disclosure. This figure shows the detour operation in the event of a failure in the network system according to Embodiment 4 of this disclosure.

[0015] The embodiments for implementing this disclosure will be described in detail below with reference to the attached drawings. In each drawing, the same or corresponding parts will be denoted by the same reference numerals. The explanation of such parts will be simplified or omitted as appropriate.

[0016] Embodiment 1. Figure 1 is a schematic diagram showing the configuration of a network system according to Embodiment 1 of the present disclosure. The network system is formed within and between train sets for devices installed in a train consisting of at least one train set to communicate with other train devices within or between train sets. As shown in Figure 1, the network system 1 is formed in a train consisting of four train sets 2a, 2b, 2c, and 2d. Network system 1 comprises ECN3a (ECN#1), ECN3b (ECN#2), ECN3c (ECN#3), ECN3d (ECN#4), source device 4, destination device 5, ETB6a (ETB (Line A)), ETB6b (ETB (Line B)), ETBN7a (ETBN#1), ETBN7b (ETBN#2), ETBN7c (ETBN#3), ETBN7d (ETBN#4), ETBN7e (ETBN#5), ETBN7f (ETBN#6), ETBN7g (ETBN#7), and ETBN7h (ETBN#8).

[0017] ECN3a (ECN#1) is one of the ECNs used for communication within a network. ECN3a (ECN#1) is an ECN located within network 2a and is formed by a source device 4, Ethernet cables (not shown) connecting the devices, and relay devices (not shown). ECN3b (ECN#2) is one of the ECNs, located within network 2b and is formed by Ethernet cables (not shown) connecting the devices, and relay devices (not shown). ECN3c (ECN#3) is one of the ECNs, located within network 2c and is formed by Ethernet cables (not shown) connecting the devices, and relay devices (not shown). ECN3d (ECN#4) is one of the ECNs, located within network 2d and is formed by a destination device 5, Ethernet cables (not shown) connecting the devices, and relay devices (not shown). The source device 4 and destination device 5 may be located within another ECN.

[0018] The source device 4 is an in-train device such as a propulsion control device or a braking device. When communicating within a network system, it is the device that transmits the communication data.

[0019] Destination device 5 is an in-train device such as a propulsion control device or a braking device. When communicating within a network system, it is the device that serves as the destination for communication data.

[0020] ETB6a (ETB (Line A)) is a network for communication between train sets 2a, 2b, 2c, and 2d, and is formed by ETBN7a (ETBN#1), ETBN7c (ETBN#3), ETBN7e (ETBN#5), ETBN7g (ETBN#7), and Ethernet cables connecting the devices. ETB6b (ETB (Line B)) is a network for communication between train sets 2a, 2b, 2c, and 2d, and is formed by ETBN7b (ETBN#2), ETBN7d (ETBN#4), ETBN7f (ETBN#6), ETBN7h (ETBN#8), and Ethernet cables connecting the devices.

[0021] ETBN7a (ETBN#1) is a device installed in train set 2a for inter-train set communication. ETBN7c (ETBN#3) is installed in train set 2b, ETBN7e (ETBN#5) is installed in train set 2c, and ETBN7g (ETBN#7) is installed in train set 2d. ETBN7c (ETBN#3), ETBN7e (ETBN#5), and ETBN7g (ETBN#7) are devices for inter-train set communication. ETBN7a (ETBN#1), ETBN7c (ETBN#3), ETBN7e (ETBN#5), and ETBN7g (ETBN#7) are connected to each other by Ethernet cables, forming ETB6a (ETB (Line A)).

[0022] ETBN7b (ETBN#2) is a device installed in train set 2a for inter-train set communication. ETBN7d (ETBN#4) is installed in train set 2b, ETBN7f (ETBN#6) is installed in train set 2c, and ETBN7h (ETBN#8) is installed in train set 2d. ETBN7d (ETBN#4), ETBN7f (ETBN#6), and ETBN7h (ETBN#8) are devices for inter-train set communication. ETBN7b (ETBN#2), ETBN7d (ETBN#4), ETBN7f (ETBN#6), and ETBN7h (ETBN#8) are connected to each other by Ethernet cables to form ETB6b (ETB (Line B)).

[0023] Arrow 8 indicates the direction of the train's movement, and in Figure 1, the direction of arrow 8 is from Dir2 to Dir1.

[0024] ECN3a (ECN#1) is connected to ETBN7a (ETBN#1) via an Ethernet cable. Furthermore, ECN3a (ECN#1) is connected to ETBN7b (ETBN#2) via an Ethernet cable.

[0025] When transmitting data from the source device 4 to the destination device 5, the source device 4 duplicates the data and sends the same data separately to ETB 6a (ETB (Line A)) and ETB 6b (ETB (Line B)), and performs inter-system broadcast IP communication via ETB 6a (ETB (Line A)) and ETB 6b (ETB (Line B)).

[0026] Figure 2 is a schematic diagram illustrating a failure in the configuration of the network system according to Embodiment 1 of this disclosure.

[0027] As shown in Figure 2, network system 1 is experiencing a failure between ETBN7a (ETBN#1) and ETBN7c (ETBN#3) of ETB6a (ETB (Line A)). Furthermore, network system 1 is experiencing a failure between ETBN7d (ETBN#4) and ETBN7f (ETBN#6) of ETB6b (ETB (Line B)).

[0028] When transmitting data from source device 4 to destination device 5, source device 4 duplicates the data and sends the same data separately to ETB6a (ETB (Line A)) and ETB6b (ETB (Line B)), performing inter-system broadcast IP communication via ETB6a (ETB (Line A)) and ETB6b (ETB (Line B)). However, due to failures between ETBN7a (ETBN#1) and ETBN7c (ETBN#3) and between ETBN7d (ETBN#4) and ETBN7f (ETBN#6), communication is not possible via either ETB6a (ETB (Line A)) or ETB6b (ETB (Line B)). Therefore, through the operation of the network system described later, a route is created to bypass the fault, and by bypassing the fault, even if a failure occurs in the ETB, inter-train communication can be continued at the ETB where the failure occurred.

[0029] Figure 3 is a configuration diagram showing an ETBN of a network system according to Embodiment 1 of the present disclosure. As shown in Figure 3, the ETBN 100 includes a routing function unit 200, a switching function unit 300, a NW (Network) fault information management function unit 400, a VLAN table 500, and a VID setting function unit 600.

[0030] The routing function unit 200 includes a relay function unit 201, a frame rewriting function unit 202, an R-NAT (Railway-Network Address Translation) table 203, a routing table 204, and a routing entry rewriting function unit 205.

[0031] When the ETBN 100 receives data while the source device 4 is transmitting data to the destination device 5, the relay function unit 201 performs IP routing and relays the data.

[0032] The frame rewriting function unit 202 is provided in the relay function unit 201 and rewrites the destination in the data when the ETBN 100 receives data.

[0033] The R-NAT table 203 is used to convert Consist network addresses to Train network addresses when relaying data from the ECN to the ETB. Furthermore, it is also used to convert Train network addresses to Consist network addresses when relaying data from the ETB to the ECN.

[0034] Figure 4 shows the R-NAT table of the network system according to Embodiment 1 of the present disclosure. As shown in Figure 4, the R-NAT table 203 holds a pair of Consist network addresses and Train network addresses as a single entry and translates the network addresses of each other. The Consist network address is a unique IP address within the ECN. The Train network address is a unique IP address across the entire train.

[0035] The routing table 204 is used to determine the next destination of the received data when performing IP routing on the data received by the ETBN 100.

[0036] Figure 5 shows a routing table of a network system according to Embodiment 1 of the present disclosure. As shown in Figure 5, the routing table 204 holds VLAN ID, Network Destination, Netmask, Gateway, Interface, and Metric as a single entry. The routing table 204 is searched using the VLAN ID and destination IP address of the received data as search keys, and the search results, Gateway and Interface, are determined as the next destination for the received data. Metric is a value used to determine which search result to adopt if there are multiple search results, and the entry with the smaller Metric is adopted as the search result.

[0037] The routing entry rewriting function unit 205 modifies the configuration information of a specific entry registered in the routing table 204 according to the status of each ETB link in the ETB link status table maintained by the NW failure information management function unit 400, which will be described later.

[0038] The switching function unit 300 includes a transfer function unit 301, a frame rewriting function unit 302, a frame transfer guard function unit 303, an FDB (Filtering-DataBase) 304, and an FDB entry rewriting function unit 305.

[0039] When the transfer function unit 301 receives data, it refers to the FDB 304 and transfers the data to Layer 2.

[0040] The frame rewriting function unit 302 is provided in the transfer function unit 301 and rewrites the destination MAC address of the data to be transferred according to the status of each ETB link in the ETB link status table held by the NW failure information management function unit 400, which will be described later.

[0041] The frame transfer guard function unit 303 is provided in the transfer function unit 301, and when the transfer function unit 301 floods data having an unlearned MAC address as the destination MAC address, the data is not transferred to an ETB link in an abnormal state.

[0042] The FDB 304 is used to determine the next destination of the received data when performing layer 2 transfer on the received data.

[0043] FIG. 6 is a diagram showing the FDB of the network system according to Embodiment 1 of the present disclosure. As shown in FIG. 6, the FDB 304 holds a MAC address, a VLAN ID, and a Port as one entry. Using the destination MAC address and VLAN ID of the received data as search keys, the FDB 304 is searched, and the Port that is the search result is determined as the next destination of the received data. If no matching entry exists when searching the FDB 304, the data is flooded to all Ports other than the Port that received the data.

[0044] The FDB entry rewriting function unit 305 changes the setting information of the entries registered in the FDB 304 according to the state of each ETB link in the ETB link state table held by the NW failure information management function unit 400 described later.

[0045] The NW failure information management function unit 400 manages the state of the ETB links included in the ETBN 100 in an ETB link state table.

[0046] FIG. 7 is a diagram showing the ETB link state table of the network system according to Embodiment 1 of the present disclosure. As shown in FIG. 7, the ETB link state table holds an ETB link, the state of the previous ETB link, and the current ETB link state as one entry.

[0047] The ETB link indicates the ETB links included in the ETBN 100. There are four ETB links: the Dir1 link of the reference ETBN, the Dir2 link of the reference ETBN, the Dir1 link of the opposing ETBN, and the Dir2 link of the opposing ETBN.

[0048] The reference ETBN refers to the ETBN100 itself equipped with an ETB link state table. The Dir1 link of the reference ETBN indicates the link of the reference ETBN in the Dir1 direction of the train. For example, in FIG. 1, if the reference ETBN is ETBN7c (ETBN#3), the Dir1 link of the reference ETBN is the link connecting ETBN7a (ETBN#1) and ETBN7c (ETBN#3), which is the link of ETBN7c (ETBN#3) in the Dir1 direction of the train.

[0049] The Dir2 link of the reference ETBN indicates the link of the reference ETBN in the Dir2 direction of the train. For example, in FIG. 1, if the reference ETBN is ETBN7c (ETBN#3), the Dir2 link of the reference ETBN is the link connecting ETBN7c (ETBN#3) and ETBN7e (ETBN#5), which is the link of ETBN7c (ETBN#3) in the Dir2 direction of the train.

[0050] The opposite ETBN refers to the ETBN existing on the opposite ETB Line connected to the reference ETBN via the ECN. For example, in FIG. 1, if the reference ETBN is ETBN7c (ETBN#3), the opposite ETBN is ETBN7d (ETBN#4); if the reference ETBN is ETBN7d (ETBN#4), the opposite ETBN is ETBN7c (ETBN#3).

[0051] The NW failure information management function unit 400 periodically determines the state of each ETB link, specifically normal or abnormal, and sets it in the ETB link state table. Normal and abnormal may be defined, for example, as the link-up state and link-down state of the ETB link. Also, for example, normal and abnormal may be determined by transmitting and receiving data for link alive / dead monitoring. The latest state of each ETB link is regarded as the current ETB link state, and the state one time before is regarded as the previous ETB link state.

[0052] Figure 8 shows the VLAN table of a network system according to Embodiment 1 of the present disclosure. As shown in Figure 8, the VLAN table 500 holds entries for each port of the ETBN 100, namely the VLAN type, i.e., port VLAN or tag VLAN, and the VLAN ID, i.e., the VLAN identifier. When the relay function unit 201 and the forwarding function unit 301 transmit data, the VLAN ID of the data to be transmitted must match the VLAN ID of the data transmission port in the entries held by the VLAN table 500. If they do not match, the data cannot be transmitted.

[0053] The VID setting function unit 600 sets or deletes a specific VID for a specific port entry in the VLAN table 500, according to the status of each ETB link in the ETB link status table held by the NW failure information management function unit 400.

[0054] Next, the operation of the network system according to Embodiment 1 of this disclosure will be described. Figure 9 is a diagram showing the occurrence of a failure in the network system according to Embodiment 1 of this disclosure.

[0055] As shown in Figure 9, a failure has occurred between ETBN7d (ETBN#4) and ETBN7f (ETBN#6) in network system 1. Due to this failure, inter-system communication cannot be continued between ETBN7d (ETBN#4) and ETBN7f (ETBN#6) of ETB6b (ETB (Line B)) in network system 1. Therefore, by creating a route that bypasses the failure and bypassing the failure, inter-system communication can be continued at the ETB where the failure occurred.

[0056] Figure 10 shows the bypass operation in the event of a failure in the network system according to Embodiment 1 of the present disclosure. As shown in Figure 10, different VLAN IDs are assigned to the links between ETB 6a (ETB (Line A)) and each ECN 3b (ECN #2), 3c (ECN #3) of the network system 1, the links between ETB 6b (ETB (Line B)) and each ECN 3b (ECN #2), 3c (ECN #3), and ETB 6b (ETB (Line B)). In Figure 10, the link between ETB6a (ETB (Line A)) and each ECN3b (ECN#2) and 3c (ECN#3) is assigned ECN VID1, the link between ETB6b (ETB (Line B)) and each ECN3b (ECN#2) and 3c (ECN#3) is assigned ECN VID2, and ETB6b (ETB (Line B)) is assigned ETB VID. When the source device 4 within ECN3a (ECN#1) broadcasts data to devices in other configurations, it uses the VLAN ID (ECN VID1) of the link between ETB6a (ETB (Line A)) and each ECN3b (ECN#2), 3c (ECN#3) and the VLAN ID (ECN VID2) of the link between ETB6b (ETB (Line B)) and each ECN3b (ECN#2), 3c (ECN#3).

[0057] In Figure 10, ETBN7d (ETBN#4) periodically updates the ETB link status table maintained by the NW fault information management function unit 400. In network system 1, if a fault occurs between ETBN7d (ETBN#4) and ETBN7f (ETBN#6), and ETBN7d (ETBN#4) is used as the reference ETBN, the current ETB link status of the reference ETBN Dir2 link in the ETB link status table of ETBN7d (ETBN#4) becomes abnormal.

[0058] The routing entry rewriting function unit 205 of ETBN7d (ETBN#4) changes the Interface of all entries in the routing table 204 where the Network Destination is equal to the network portion of the network address of the ECN Train network address located in the Dir2 link direction of the failed reference ETBN, from the ETB port of the routing function unit 200 to the ECN port of the routing function unit 200. Furthermore, in the routing table 204, for all entries where the Network Destination is equal to the network portion of the network address of the ECN Train network address located in the Dir2 link direction of the failed reference ETBN, it changes the Gateway from the IP address of the ETBN connected beyond the Dir2 link of the failed reference ETBN to the IP address of the opposing ETBN, ETBN7c (ETBN#3). As a result, when ETBN7d (ETBN#4) receives data, as indicated by block arrow 9a, it will not forward the data to the ETB link on the ETBN7f (ETBN#6) side where the failure is occurring, but will instead forward it to the ECN link on the ECN3b (ECN#2) side, thereby bypassing the failure.

[0059] Figure 11 is a diagram showing the bypass VID setting operation in a network system according to Embodiment 1 of the present disclosure. As shown in Figure 11, a failure has occurred between ETBN7d (ETBN#4) and ETBN7f (ETBN#6) in the network system 1. When ETBN7c (ETBN#3) is used as the reference ETBN, the current ETB link status of the Dir2 link of the opposing ETBN in the ETB link status table becomes abnormal. The VID setting function unit 600 of ETBN7c (ETBN#3) sets the ECN VID2, which is set between the ECN3b (ECN#2) to which it is connected and the opposing ETBN, ETBN7d (ETBN#4), as the bypass VID in the entry in the VLAN table 500 for the ECN port of the routing function unit 200.

[0060] When ETBN7e (ETBN#5) is used as the reference ETBN, the current ETB link status of the Dir1 link of the opposing ETBN in the ETB link status table becomes abnormal. The VID setting function unit 600 of ETBN7e (ETBN#5) sets the ECN VID2, which is set between the ECN3c (ECN#3) to which it is connected and the opposing ETBN, ETBN7f (ETBN#6), as the bypass VID for the ECN port of the routing function unit 200 in the VLAN table 500.

[0061] The VID setting function unit 600 of ETBN7c (ETBN#3) sets a different ETB VID (backup) to the ETB port of the routing function unit 200, as per the entry in the VLAN table 500. Furthermore, the VID setting function unit 600 of ETBN7c (ETBN#3) sets a spare ETB VID to the ECN port of the switching function unit 300, as per the entry in the VLAN table 500. In addition, the VID setting function unit 600 of ETBN7c (ETBN#3) sets a spare ETB VID to the ETB port of the switching function unit 300, as per the entry in the VLAN table 500, in the same direction (Dir2) as the ETB link where the opposing ETBN, ETBN7d (ETBN#4), has failed.

[0062] The VID setting function unit 600 of ETBN7e (ETBN#5) sets the ETB VID (reserve) to the ETB port of the routing function unit 200, which is an entry in the VLAN table 500. Furthermore, the VID setting function unit 600 of ETBN7e (ETBN#5) sets the ETB VID (reserve) to the ECN port of the switching function unit 300, which is an entry in the VLAN table 500. In addition, the VID setting function unit 600 of ETBN7e (ETBN#5) sets the ETB VID (reserve) to the ETB port of the switching function unit 300, which is an entry in the VLAN table 500, in the same direction (Dir1) as the ETB link where the failure occurred in the opposing ETBN, ETBN7f (ETBN#6).

[0063] As a result, as indicated by block arrow 9b, ETBN7c (ETBN#3) and ETBN7e (ETBN#5) can transfer data using ECN VID2 and ETB VID (reserve).

[0064] Figure 12 shows the bypass operation in the event of a failure in the network system according to Embodiment 1 of the present disclosure. As shown in Figure 12, the routing entry rewriting function unit 205 of ETBN 7e (ETBN #5) determines in the routing table 204 whether the Network Destination is equal to the network portion of the Train network address located in the opposite direction from the failed ETB link of the opposing ETBN, ETBN 7f (ETBN #6), i.e., in the Dir2 direction, and whether the VLAN ID is ECN VID2. For all entries that match the determination, the interface is changed from the ETB port of the routing function unit 200 to the ECN port of the routing function unit 200. Furthermore, for all entries that match the criteria, the gateway is changed from the IP address of the ETBN connected in the opposite direction (Dir2 direction) from the ETB link where the failure occurred to the opposite ETBN's IP address of the opposite ETBN, ETBN7f (ETBN#6). As a result, when ETBN7e (ETBN#5) receives data, as indicated by block arrow 9c, it becomes possible to bypass the failure and forward the data that ETBN7d (ETBN#4) would normally send to the failed ETBN7f (ETBN#6) to the opposite ETBN, ETBN7f (ETBN#6).

[0065] Figure 13 is a flowchart showing the bypass operation (ETBN setting change) in the network system according to Embodiment 1 of this disclosure when a failure occurs.

[0066] In Step 101 of Figure 13, the reference ETBN periodically monitors the ETB link status in the Dir1 and Dir2 directions. When a failure occurs, the ETB link status in the Dir1 or Dir2 direction of the reference ETBN becomes abnormal, and the current ETB link status in the ETB link status table held by the NW failure information management function unit 400 becomes abnormal. The reference ETBN checks the previous ETB link status and the current ETB link status in the ETB link status table held by its own NW failure information management function unit 400. If the previous ETB link status was normal and the current ETB link status is abnormal, it executes Step 102. If the current ETB link status is normal, it executes Step 103.

[0067] In Step 102 of Figure 13, the routing entry rewriting function unit 205 of the reference ETBN modifies the entry settings in the routing table 204 so that when the reference ETBN receives data, it does not forward it to the faulty ETB link where the failure is occurring, but instead forwards it to the ECN link, thereby bypassing the failure.

[0068] In Step 103 of Figure 13, the opposing ETBN periodically monitors the ETB link status in the Dir1 and Dir2 directions. When a failure occurs, the ETB link status in either the Dir1 or Dir2 direction of the opposing ETBN becomes abnormal, and the current ETB link status in the ETB link status table held by the NW failure information management function unit 400 becomes abnormal. The opposing ETBN checks the previous ETB link status and the current ETB link status in the ETB link status table held by its own NW failure information management function unit 400. If the previous ETB link status was normal and the current ETB link status is abnormal, it executes Step 104. If the current ETB link status is normal, it executes Step 105.

[0069] In Step 104 of Figure 13, the VID setting function unit 600 of the reference ETBN sets ETB VID (backup) as a bypass VID for the ETB port or ECN port of the VLAN table 500. Furthermore, the VID setting function unit 600 of the reference ETBN sets ECN VID1 or ECN VID2 as a bypass VID for the ETB port or ECN port of the VLAN table 500.

[0070] In Step 105 of Figure 13, the opposing ETBN checks the previous ETB link state and the current ETB link state in the ETB link state table held by its own NW fault information management function unit 400. If either the Dir1 direction or the Dir2 direction has a normal ETB link state in the previous instance and an abnormal ETB link state in the current instance, Step 106 is executed. If it is normal, the process ends.

[0071] In Step 106 of Figure 13, the routing entry rewriting function unit 205 of the reference ETBN modifies the entry settings in the routing table 204 so that, when the reference ETBN receives data, the data that the opposing ETBN should have originally sent to the ETBN experiencing the failure can be forwarded to the opposing ETBN by bypassing the failure.

[0072] Figure 14 is a flowchart showing the bypass operation (ETBN data processing) in the event of a failure in the network system according to Embodiment 1 of this disclosure.

[0073] In Step 201 of Figure 14, if the VID of the VLAN tag of the data received by the ETBN is the ETB VID, Step 202 is executed. If the VID of the VLAN tag of the received data is not the ETB VID, Step 204 is executed.

[0074] In Step 202 of Figure 14, if the destination of the received data is an ETB link in the opposite direction to the receiving link, and the ETB link in the opposite direction to the receiving link is abnormal, Step 203 is executed. Otherwise, the process is terminated.

[0075] In Step 203 of Figure 14, the frame rewriting function unit 302 rewrites the destination MAC address of the data to be transferred. The frame transfer guard function unit 303 prevents data from being transferred to an ETB link where the ETB link status is abnormal. After these processes are executed, the process terminates.

[0076] In Step 204 of Figure 14, if the VID of the VID tag of the data received by the ETBN is the ETB VID (reserve), Step 205 is executed. If the VID of the VLAN tag of the received data is not the ETB VID, the process is terminated.

[0077] In Step 205 of Figure 14, the opposing ETBN checks the current ETB link status in the ETB link status table held by its own NW fault information management function unit 400. If either the Dir1 direction or the Dir2 direction is abnormal, it executes Step 206. If both the Dir1 and Dir2 directions are normal, the process ends.

[0078] In Step 206 of Figure 14, the frame rewriting function unit 302 rewrites the destination MAC address of the data to be transferred and terminates the process.

[0079] As described above, the network system 1 according to this disclosure is a network system comprising: ETBN 7a, 7c, 7e, 7g provided within a train consisting of one or more train sets and used for communication between train sets; ETBN 7b, 7d, 7f, 7h provided within a train set and used for communication between train sets; ETB 6a formed by connecting the ETBN 7a, 7c, 7e, 7g provided in each train set to each other; ETB 6b formed by connecting the ETBN 7b, 7d, 7f, 7h provided in each train set to each other; and ECN 3a, 3b, 3c, 3d provided within a train set and separately connected to ETBN 7a, 7c, 7e, 7g and ETBN 7b, 7d, 7f, 7h, and performing inter-train set broadcast IP communication using ETB 6a and ETB 6b. Furthermore, this network system 1 includes an NW fault information management unit 400 that manages information on fault locations in ETB 6a and ETB 6b, a VID setting function unit 600 that sets VLANs in either ETB 6a, ETB 6b, or ECN 3a, 3b, 3c, or 3d, and a routing entry rewriting function unit 205 that sets routing entries for ETBN 7a, 7c, 7e, 7g and ETBN 7b, 7d, 7f, or 7h. In addition, when this network system 1 receives a frame, it includes a forwarding function unit 301 that determines whether the frame is destined for a fault location managed by the NW fault information management unit 400, and a frame rewriting function unit 202 that rewrites the destination of the frame for frames that the forwarding function unit 301 has determined to be destined for a fault location. For example, if a failure occurs between ETBN7d and ETBN7f of ETB6b, the VID setting function unit 600 sets a bypass VLAN (ECN VID2 → ETB VID (backup) → ECN VID2) between the ECN3b of the preceding configuration 2b where the failure occurred, the ECN3c of the subsequent configuration 2c where the failure occurred, and the ETB6a between the preceding configuration 2b and the subsequent configuration 2c.Furthermore, the routing entry rewriting function unit 205 rewrites the routing entry with ETBN 7h as the destination in the downstream configuration 2d of the location where the failure occurred to a routing entry with ETBN 7c as the destination, and the frame whose destination has been rewritten by the frame rewriting function unit 202 is routed using the rewritten routing entry and transmitted via the bypass VLAN.

[0080] Thus, the network system according to this embodiment can bypass failures by setting a bypass VID and transferring received data. As a result, even if a failure occurs in the ETB, inter-system communication can continue at the failed ETB.

[0081] Embodiment 2. The network system of Embodiment 2 will be described with reference to Figures 15 and 16. In the description of Embodiment 2, the same reference numerals as in Embodiment 1 indicate the same or corresponding parts.

[0082] Figure 15 shows a diagram illustrating fault recovery in a network system according to Embodiment 2 of this disclosure.

[0083] As shown in Figure 15, the fault that occurred between ETBN7d (ETBN#4) and ETBN7f (ETBN#6) in network system 1 has been resolved. This fault resolution enables inter-system communication between ETBN7d (ETBN#4) and ETBN7f (ETBN#6) of ETB6b (ETB (Line B)) in network system 1. Therefore, by deleting the route that bypassed the fault and returning to the route before the fault occurred without bypassing it, the redundancy of the network system as it was before the fault can be obtained.

[0084] Figure 16 is a flowchart showing the operation (ETBN data processing) during fault recovery in the network system according to Embodiment 2 of this disclosure.

[0085] In Step 107 of Figure 16, the reference ETBN periodically monitors the ETB link status in the Dir1 and Dir2 directions. When a fault is resolved, the ETB link status in the Dir1 or Dir2 direction of the reference ETBN becomes normal, and the current ETB link status in the ETB link status table held by the NW fault information management function unit 400 becomes normal. The reference ETBN checks the previous ETB link status and the current ETB link status in the ETB link status table held by its own NW fault information management function unit 400. If the previous ETB link status was abnormal and the current ETB link status is normal, it executes Step 108. If it is abnormal, it executes Step 109.

[0086] In Step 108 of Figure 16, the routing entry rewriting function unit 205 of the reference ETBN reverts the entry configuration information that was changed in Step 102 of Figure 13 back to the configuration information of the entry before the change. After restoring the configuration information, Step 109 is executed.

[0087] In Step 109 of Figure 16, the opposing ETBN periodically monitors the ETB link status in the Dir1 and Dir2 directions. When the fault is resolved, the ETB link status in either the Dir1 or Dir2 direction of the opposing ETBN becomes normal, and the current ETB link status in the ETB link status table held by the NW fault information management function unit 400 becomes normal. The opposing ETBN checks the previous ETB link status and the current ETB link status in the ETB link status table held by its own NW fault information management function unit 400. If the previous ETB link status was abnormal and the current ETB link status is normal, it executes Step 110. If the current ETB link status is abnormal, it terminates the process.

[0088] In Step 110 of Figure 16, the VID setting function unit 600 of the reference ETBN deletes the ETB VID (reserve) for the ETB port and ECN port in the VLAN table 500, which were set as bypass VIDs. Furthermore, the VID setting function unit 600 of the reference ETBN deletes ECN VID1 and ECN VID2, which were set as bypass VIDs for the ETB port or ECN port in the VLAN table 500. Then, Step 111 is executed.

[0089] In Step 111 of Figure 16, the routing entry rewriting function unit 205 of the reference ETBN reverts the entry settings information that was changed in Step 106 of Figure 13 back to the settings of the entry before the change. After restoring the settings information, the process ends.

[0090] As described above, when the failure between ETBN7d (ETBN#4) and ETBN7f (ETBN#6) of ETB6b (ETB (Line B)) is resolved, network system 1 can obtain the redundancy of the network system before the failure by deleting the route that bypassed the failure and returning to the route that was in place before the failure occurred.

[0091] Embodiment 3. The network system of Embodiment 3 will be described with reference to Figures 17, 18, and 19. In the description of Embodiment 3, the same reference numerals as in Embodiments 1 and 2 indicate the same or corresponding parts.

[0092] Figure 17 is a schematic diagram showing the configuration of a network system according to Embodiment 3 of the present disclosure. As shown in Figure 17, the network system 1 includes a bypass line 10a that bypasses ECN 3a (ECN #1) between ETBN 7a (ETBN #1) and ETBN 7b (ETBN #2). The network system 1 includes a bypass line 10b that bypasses ECN 3b (ECN #2) between ETBN 7c (ETBN #3) and ETBN 7d (ETBN #4). The network system 1 includes a bypass line 10c that bypasses ECN 3c (ECN #3) between ETBN 7e (ETBN #5) and ETBN 7f (ETBN #6). Network system 1 includes a bypass line 10d that bypasses ECN 3d (ECN #4) between ETBN 7g (ETBN #7) and ETBN 7h (ETBN #8).

[0093] When transmitting data from the source device 4 to the destination device 5, similar to Embodiments 1 and 2, the source device 4 duplicates the data and transmits the same data separately to ETB 6a (ETB (Line A)) and ETB 6b (ETB (Line B)), and performs inter-system broadcast IP communication via ETB 6a (ETB (Line A)) and ETB 6b (ETB (Line B)).

[0094] Figure 18 is a schematic diagram illustrating a failure in the configuration of a network system according to Embodiment 3 of this disclosure.

[0095] As shown in Figure 18, network system 1 is experiencing a failure between ETBN7a (ETBN#1) and ETBN7c (ETBN#3) of ETB6a (ETB (Line A)). Furthermore, network system 1 is experiencing a failure between ETBN7d (ETBN#4) and ETBN7f (ETBN#6) of ETB6b (ETB (Line B)).

[0096] When transmitting data from source device 4 to destination device 5, source device 4 duplicates the data and sends the same data separately to ETB6a (ETB (Line A)) and ETB6b (ETB (Line B)), performing inter-system broadcast IP communication via ETB6a (ETB (Line A)) and ETB6b (ETB (Line B)). However, due to failures between ETBN7a (ETBN#1) and ETBN7c (ETBN#3) and between ETBN7d (ETBN#4) and ETBN7f (ETBN#6), communication is not possible via either ETB6a (ETB (Line A)) or ETB6b (ETB (Line B)). Therefore, by creating a bypass route through the operation of the network system described later, and bypassing the fault via bypass lines 10b and 10c, inter-train communication can be continued at the ETB where the failure occurred.

[0097] Figure 19 is a configuration diagram showing an ETBN of a network system according to Embodiment 3 of the present disclosure. As shown in Figure 19, the routing function unit 200 of the ETBN 100 is equipped with a port directly connected to the opposing ETBN as a bypass line.

[0098] Figure 20 is a diagram showing the bypass operation in the event of a failure in a network system according to Embodiment 3 of this disclosure.

[0099] The routing entry rewriting function unit 205 of ETBN7d (ETBN#4) changes the Interface of all entries in the routing table 204 where the Network Destination is equal to the network portion of the network address of the ECN's Train network address located in the Dir2 link direction of the failed reference ETBN, from the ETB port of the routing function unit 200 to the port of the opposite ETBN directly connected to the routing function unit 200. Furthermore, in the routing table 204, for all entries where the Network Destination is equal to the network portion of the network address of the ECN's Train network address located in the Dir2 link direction of the failed reference ETBN, it changes the Gateway from the IP address of the ETBN connected beyond the Dir2 link of the failed reference ETBN to the IP address of the opposite ETBN, ETBN7c (ETBN#3). As a result, when ETBN7d (ETBN#4) receives data, as indicated by block arrow 11a, it does not forward the data to the ETB link on the side of ETBN7f (ETBN#6) where the failure is occurring, but instead forwards it to the port directly connected to the opposite ETBN, thereby bypassing the failure.

[0100] Figure 21 is a diagram showing the bypass VID setting operation in a network system according to Embodiment 3 of the present disclosure. As shown in Figure 21, a failure has occurred between ETBN7d (ETBN#4) and ETBN7f (ETBN#6) in the network system 1. When ETBN7c (ETBN#3) is used as the reference ETBN, the current ETB link status of the Dir2 link of the opposing ETBN in the ETB link status table becomes abnormal. The VID setting function unit 600 of ETBN7c (ETBN#3) sets the ECN VID2, which is set between the ECN3b (ECN#2) to which it is connected and the opposing ETBN, ETBN7d (ETBN#4), as the bypass VID in the entry in the VLAN table 500 for the port of the routing function unit 200 directly connected to the opposing ETBN.

[0101] When ETBN7e (ETBN#5) is used as the reference ETBN, the current ETB link status of the Dir1 link of the opposing ETBN in the ETB link status table becomes abnormal. The VID setting function unit 600 of ETBN7e (ETBN#5) sets the ECN VID2, which is set between the ECN3c (ECN#3) to which it is connected and the opposing ETBN, ETBN7f (ETBN#6), as the bypass VID for the port of the routing function unit 200 directly connected to the opposing ETBN in the VLAN table 500.

[0102] The VID setting function unit 600 of ETBN7c (ETBN#3) sets a different ETB VID (backup) to the ETB port of the routing function unit 200, as per the entry in the VLAN table 500. Furthermore, the VID setting function unit 600 of ETBN7c (ETBN#3) sets a spare ETB VID to the ECN port of the switching function unit 300, as per the entry in the VLAN table 500. In addition, the VID setting function unit 600 of ETBN7c (ETBN#3) sets a spare ETB VID to the ETB port of the switching function unit 300, as per the entry in the VLAN table 500, in the same direction (Dir2) as the ETB link where the opposing ETBN, ETBN7d (ETBN#4), has failed.

[0103] The VID setting function unit 600 of ETBN7e (ETBN#5) sets the ETB VID (reserve) to the ETB port of the routing function unit 200, which is an entry in the VLAN table 500. Furthermore, the VID setting function unit 600 of ETBN7e (ETBN#5) sets the ETB VID (reserve) to the ECN port of the switching function unit 300, which is an entry in the VLAN table 500. In addition, the VID setting function unit 600 of ETBN7e (ETBN#5) sets the ETB VID (reserve) to the ETB port of the switching function unit 300, which is an entry in the VLAN table 500, in the same direction (Dir1) as the ETB link where the failure occurred in the opposing ETBN, ETBN7f (ETBN#6).

[0104] As a result, as indicated by block arrow 11b, ETBN7c (ETBN#3) and ETBN7e (ETBN#5) can transfer data using ECN VID2 and ETB VID (reserve).

[0105] Figure 22 shows the bypass operation in the event of a failure in a network system according to Embodiment 3 of the present disclosure. As shown in Figure 22, the routing entry rewriting function unit 205 of ETBN7e (ETBN#5) determines in the routing table 204 whether the Network Destination is equal to the network portion of the Train network address located in the opposite direction to the failed ETB link of the opposing ETBN, ETBN7f (ETBN#6), i.e., in the Dir2 direction, and whether the VLAN ID is ECN VID2. For all entries that match the determination, the interface is changed from the ETB port of the routing function unit 200 to the port directly connected to the opposing ETBN of the routing function unit 200. Furthermore, for all entries that match the determination, the gateway is changed from the IP address of the ETBN connected in the opposite direction (Dir2 direction) from the ETB link where the opposing ETBN failed, to the IP address of the opposing ETBN, ETBN7f (ETBN#6). As a result, when ETBN7e (ETBN#5) receives data, as indicated by block arrow 11c, it becomes possible to forward the data that ETBN7d (ETBN#4) would normally send to the failing ETBN7f (ETBN#6) to the opposing ETBN, ETBN7f (ETBN#6), via the bypass line 10c, bypassing the failure.

[0106] As described above, the network system 1 creates a route to bypass faults and bypasses the faults via bypass lines 10b and 10c, so that even if a fault occurs in ETB 6b, inter-system communication can continue at the ETB 6b where the fault occurred. Furthermore, because the network system 1 uses bypass lines 10b and 10c, it has less transmission delay than embodiments 1 and 2 which use ECNs 3b and 3c for bypassing.

[0107] Embodiment 4. The network system of Embodiment 4 will be described with reference to Figures 23, 24, 25, and 26. In the description of Embodiment 4, the same reference numerals as in Embodiments 1 to 3 indicate the same or corresponding parts.

[0108] Figure 23 is a diagram showing the status table of the opposite ETBN direct connection port of the network system according to Embodiment 4 of the present disclosure. As shown in Figure 23, the opposite ETBN direct connection port status table 700 holds the opposite ETBN direct connection port provided on the ETBN, the previous port status, and the current port status as a single entry.

[0109] The NW fault information management function unit 400 periodically determines the status of each ETB link, as well as the status of the opposing ETBN-connected port, specifically whether it is normal or abnormal, and sets this in the opposing ETBN-connected port status table 700. Normal and abnormal may be defined, for example, as the link-up state and link-down state of the opposing ETBN-connected port. Alternatively, normal and abnormal status may be determined by, for example, sending and receiving data for monitoring the port's availability. The latest state of the port is set as the current port status, and the previous state is set as the previous port status.

[0110] Figure 24 is a diagram showing the bypass operation in the event of a failure in the network system according to Embodiment 4 of this disclosure.

[0111] As shown in Figure 24, in network system 1, failures have occurred in the bypass lines 10c between ETBN7d (ETBN#4) and ETBN7f (ETBN#6), and between ETBN7e (ETBN#5) and ETBN7f (ETBN#6).

[0112] The routing entry rewriting function unit 205 of ETBN7d (ETBN#4) changes the Interface of all entries in the routing table 204 where the Network Destination is equal to the network portion of the network address of the ECN Train network address located in the Dir2 link direction of the faulty reference ETBN, from the ETB port of the routing function unit 200 to the port directly connected to the opposite ETBN of the routing function unit 200. Alternatively, the modified entries may be pre-configured in the routing table 204 with a small Metric value, and then the Metric value may be increased so that these entries are adopted as search results in the routing table 204. Furthermore, in the routing table 204, for all entries where Network Destination is equal to the network portion of the network address of the ECN's Train network address located in the direction of the Dir2 link of the failed reference ETBN, the Gateway is changed from the IP address of the ETBN connected beyond the Dir2 link of the failed reference ETBN to the IP address of the opposing ETBN, ETBN7c (ETBN#3). As a result, when ETBN7d (ETBN#4) receives data, as indicated by block arrow 11a, it does not forward the data to the ETB link on the side of the failed ETBN7f (ETBN#6), but instead forwards it to the port directly connected to the opposing ETBN, thereby bypassing the failure.

[0113] Figure 25 shows the bypass VID setting operation in a network system according to Embodiment 4 of the present disclosure. As shown in Figure 25, in the network system 1, a failure has occurred in the bypass line 10c between ETBN 7d (ETBN #4) and ETBN 7f (ETBN #6), and between ETBN 7e (ETBN #5) and ETBN 7f (ETBN #6). When ETBN 7c (ETBN #3) is used as the reference ETBN, the current ETB link status of the Dir2 link of the opposing ETBN in the ETB link status table becomes abnormal. The VID setting function unit 600 of ETBN7c (ETBN#3) sets ECN VID2, which is set between ECN3b (ECN#2) to which it is connected and the opposing ETBN, ETBN7d (ETBN#4), as the bypass VID for the ECN port of the routing function unit 200 and the port directly connected to the opposing ETBN, in the entries within the VLAN table 500.

[0114] When ETBN7e (ETBN#5) is used as the reference ETBN, the current ETB link status of the Dir1 link of the opposing ETBN in the ETB link status table becomes abnormal. The VID setting function unit 600 of ETBN7e (ETBN#5) sets the ECN VID2, which is set between the ECN3c (ECN#3) to which it is connected and the opposing ETBN, ETBN7f (ETBN#6), as the bypass VID for the ECN port of the routing function unit 200 and the port directly connected to the opposing ETBN in the VLAN table 500 entries.

[0115] The VID setting function unit 600 of ETBN7c (ETBN#3) sets a different ETB VID (backup) to the ETB port of the routing function unit 200, as per the entry in the VLAN table 500. Furthermore, the VID setting function unit 600 of ETBN7c (ETBN#3) sets a spare ETB VID to the ECN port of the switching function unit 300, as per the entry in the VLAN table 500. In addition, the VID setting function unit 600 of ETBN7c (ETBN#3) sets a spare ETB VID to the ETB port of the switching function unit 300, as per the entry in the VLAN table 500, in the same direction (Dir2) as the ETB link where the opposing ETBN, ETBN7d (ETBN#4), has failed.

[0116] The VID setting function unit 600 of ETBN7e (ETBN#5) sets the ETB VID (reserve) to the ETB port of the routing function unit 200, which is an entry in the VLAN table 500. Furthermore, the VID setting function unit 600 of ETBN7e (ETBN#5) sets the ETB VID (reserve) to the ECN port of the switching function unit 300, which is an entry in the VLAN table 500. In addition, the VID setting function unit 600 of ETBN7e (ETBN#5) sets the ETB VID (reserve) to the ETB port of the switching function unit 300, which is an entry in the VLAN table 500, in the same direction (Dir1) as the ETB link where the failure occurred in the opposing ETBN, ETBN7f (ETBN#6).

[0117] As a result, as indicated by block arrow 11b, ETBN7c (ETBN#3) and ETBN7e (ETBN#5) can transfer data using ECN VID2 and ETB VID (reserve).

[0118] Figure 26 shows the bypass operation in the event of a failure in a network system according to Embodiment 4 of this disclosure. As shown in Figure 26, the routing entry rewriting function unit 205 of ETBN 7e (ETBN #5) determines in the routing table 204 whether the Network Destination is equal to the network portion of the Train network address located in the opposite direction from the failed ETB link of the opposing ETBN, ETBN 7f (ETBN #6), i.e., in the Dir2 direction, and whether the VLAN ID is ECN VID2. For all entries that match the determination, the interface is changed from the ETB port of the routing function unit 200 to the port directly connected to the opposing ETBN of the routing function unit 200. Furthermore, for all entries that match the determination, the Gateway is changed from the IP address of the ETBN connected in the opposite direction (Dir2 direction) from the ETB link where the ETBN failure occurred to the IP address of the ETBN7f (ETBN#6), which is the ETBN. Furthermore, if the current port status of the ETBN-connected port in the ETBN-connected port status table 700 is abnormal, the Interface is changed from the ETB port of the routing function unit 200 to the ECN port of the routing function unit 200 for all entries that match the determination. Furthermore, for all entries that match the determination, the Gateway is changed from the IP address of the ETBN connected in the opposite direction (Dir2 direction) from the ETB link where the ETBN failure occurred to the IP address of the ETBN7f (ETBN#6), which is the ETBN. Alternatively, the modified entry may be pre-configured in the routing table 204 with a small Metric value, and then the Metric value may be increased so that this entry is adopted as a search result in the routing table 204. This allows ETBN7e (ETBN#5) to forward data to the opposing ETBN, ETBN7f (ETBN#6), using ECN3c (ECN#3), instead of using the port directly connected to the opposing ETBN where the failure occurred, as indicated by block arrow 11d.

[0119] As described above, the network system 1 creates a route to bypass failures and bypasses the failures via the bypass line 10b, so that even if a failure occurs in the ETB 3b, inter-system communication can continue at the failed ETB 3b. Furthermore, since the network system 1 bypasses the failed bypass line 10c via the ECN 3c (ECN#3), redundancy is improved compared to Embodiment 3.

[0120] Furthermore, combining, modifying, or omitting each embodiment as appropriate is also included within the scope of the technical ideas shown in the embodiments.

[0121] 1 Network system, 2a, 2b, 2c, 2d Configuration, 3a, 3b, 3c, 3d ECN, 4 Source device, 5 Destination device, 6a, 6b ETB, 7a, 7b, 7c, 7d, 7e, 7f, 7g, 7h ETBN, 8 Arrow, 100 ETBN, 200 Routing function unit, 300 Switching function unit, 400 Network fault information management function unit, 500 VLAN table, 600 VID setting function unit, 201 Relay function unit, 202 Frame rewriting function unit, 203 R-NAT table, 204 Routing table, 205 Routing entry rewriting function unit, 301 Forwarding function unit, 302 Frame rewriting function unit, 303 Frame forwarding guard function unit, 304 FDB, 305 FDB entry rewriting function unit, 9a, 9b, 9c, 11a, 11b, 11c, 11d Block arrow, 10a, 10b, 10c, 10d Bypass line, 700 Opposite ETBN direct connection port status table

Claims

1. In a train consisting of one or more train sets, a first ETBN (Ethernet® Train Backbone Node) is provided within the train set and used for communication between train sets; a second ETBN is provided within the train set and used for communication between train sets; a first ETB (Ethernet Train Backbone) is formed by connecting the first ETBNs provided in each train set to each other; a second ETB is formed by connecting the second ETBNs provided in each train set to each other; and an ECN (Ethernet Consistent Network) is provided within the train set and is separately connected to the first ETBN and the second ETBN, and performs inter-train set broadcast IP (Internet Protocol) communication using the first ETB and the second ETB. A network system comprising: a network failure information management unit that manages information on failure locations of the first ETB and the second ETB; a VLAN setting unit that sets up a VLAN (Virtual Local Area Network) in either the first ETB, the second ETB, or the ECN; a routing setting unit that sets up routing entries for the first ETBN and the second ETBN; a forwarding function unit that, upon receiving a frame, determines whether the frame is destined for a failure location managed by the network failure information management unit; and a frame rewriting function unit that rewrites the destination of a frame for a frame that the forwarding function unit has determined to be destined for a failure location; wherein, if a failure occurs in the second ETB, the VLAN setting unit sets up a bypass VLAN between the ECN of the configuration preceding the failure location, the ECN of the configuration following the failure location, and the first ETB between the configuration preceding and following the configuration. The routing configuration unit rewrites a routing entry with the ETBN of the downstream configuration of the location where the failure occurred as the destination to a routing entry with the first ETBN as the destination, routes the frame whose destination has been rewritten by the frame rewriting function unit using the rewritten routing entry, and transmits it via the bypass VLAN.

2. When the failure of the second ETB is resolved, the VLAN setting unit deletes the setting of the bypass VLAN, the routing setting unit rewrites the routing entry to the one before the failure occurred, and routes the received frame according to the rewritten routing entry, the network system according to claim 1.

3. A network system comprising: a train consisting of one or more train sets, comprising: a first ETBN provided within a train set and used for communication between train sets; a second ETBN provided within a train set and used for communication between train sets; a first ETB formed by connecting the first ETBNs provided in each train set to each other; a second ETB formed by connecting the second ETBNs provided in each train set to each other; an ECN provided within a train set and separately connected to the first ETBN and the second ETBN, which performs inter-train set broadcast IP communication using the first ETB and the second ETB; and a bypass line connecting the first ETBN and the second ETBN provided in each train set, wherein the network system comprises: a network failure information management unit that manages information on the location of failures in the first ETB and the second ETB; The system comprises: a VLAN setting unit that sets a VLAN (Virtual Local Area Network) in either the first ETB, the second ETB, or the ECN; a routing setting unit that sets routing entries for the first ETBN and the second ETBN; a forwarding function unit that, upon receiving a frame, determines whether the frame is destined for a fault location managed by the network fault information management unit; and a frame rewriting function unit that rewrites the destination of the frame for frames that the forwarding function unit has determined to be destined for a fault location. If a failure occurs in the second ETB, the VLAN setting unit sets a bypass VLAN between the bypass line of the configuration preceding the fault location, the bypass line of the configuration following the fault location, and the first ETB between the configuration preceding and following the configuration. The routing configuration unit rewrites a routing entry with the ETBN of the downstream configuration of the location where the failure occurred as the destination to a routing entry with the first ETBN as the destination, routes the frame whose destination has been rewritten by the frame rewriting function unit using the rewritten routing entry, and transmits it via the bypass VLAN.

4. In the event of a failure in the bypass line, the VLAN setting unit sets a second bypass VLAN between the ECN of the configuration preceding the location of the failure, the ECN of the configuration following the location of the failure, and the first ETB between the configuration preceding and following the configuration, and routes the frame whose destination has been rewritten by the frame rewriting function unit using the rewritten routing entry and transmits it via the second bypass VLAN of the ECN, the network system according to claim 3.

5. The network system according to claim 1 or 3, wherein the forwarding function unit includes a frame forwarding guard function unit that does not forward data to an ETB link that is in an abnormal state when flooding data having an unlearned MAC address as the destination MAC address.

Images