JP5495175B2 - Information transfer system - Google Patents

Description

The present invention relates to an information transfer system in which a plurality of tunnel devices are connected to each other via a network and transfer multicast packets between the plurality of tunnel devices.

In recent years, the broadband of the Internet has progressed, and various contents have been IP (Internet).
Protocol) is now sent over the network. An IP network is generally connected through many routers. The router has a route table in which a route to a transfer destination is described, and transfers a packet such as a multicast packet according to the route table. This routing table is necessary for unicast, which is one-to-one communication, and multicast, which is one-to-many communication.

An IP network may be used, for example, to connect 10,000 or more field devices used in a plant or the like. In such a method of transferring packets between the field devices using the routing table described above, the burden on the router increases, and it may take time to transfer the packets, or transfer of the packets may not be possible. is there.

For example, Patent Document 1 discloses an IP network system that transfers a packet to a destination host via a clockwise route or a counterclockwise route of a ring network. According to this IP network system, packet communication is performed between hosts via a ring network connected in a ring shape by a plurality of routers. The packet includes transfer direction information indicating a clockwise route or a counterclockwise route. Based on this transfer direction information, the router sends the packet to the destination host via the clockwise route or the counterclockwise route of the ring network. Forward. Thereby, even if a failure occurs in the clockwise route or the counterclockwise route, the IP network system can transfer the packet through the other route.

FIG. 5 is a block diagram illustrating a configuration example of a conventional information transfer system 200. As shown in FIG. 5, the information transfer system 200 includes a first terminal device (hereinafter referred to as a terminal device P11),
First router (hereinafter referred to as router R11), first tunnel device (hereinafter referred to as tunnel device T11), second terminal device (hereinafter referred to as terminal device P12), second router (hereinafter referred to as router R12) ) And a second tunnel device (hereinafter referred to as tunnel device T12).

The terminal device P11, the router R11, and the tunnel device T11 are connected to each other via the bus B11, and constitute a first network (hereinafter referred to as a network N11). The terminal device P12, the router R12, and the tunnel device T12 are connected to each other via the bus B12, and constitute a second network (hereinafter referred to as a network N12). The network N11 and the network N12 are connected via the Internet IN.

As the terminal devices P11 and P12, portable information terminals, personal computers, and the like are used.
The terminal devices P11 and P12 generate a multicast packet used in multicast and transmit it to the other terminal device via the Internet IN.

The routers R11 and R12 connect the networks N11 and N12 via the Internet IN. For example, when the network N11 communicates with the network N12, communication is performed via the routers R11 and R12.

The tunnel devices T11 and T12 encapsulate or decapsulate multicast packets output from the terminal devices P11 and P22. Encapsulation means adding an IP header or various extension headers to a multicast packet, and decapsulation means returning the encapsulated multicast to the original multicast. That is, encapsulation and decapsulation are similar to encoding and decoding.

FIG. 6 is a block diagram illustrating a configuration example of the tunnel device T11. As shown in FIG. 6, the tunnel device T11 includes a reception unit 30, an encapsulation unit 31, a tunnel storage unit 20, and a transmission unit 3.
3 is provided.

The receiving unit 30 receives various packets transmitted to the tunnel device T11. For example, the receiving unit 30 receives the multicast packet D1 generated by the terminal device P11 via the bus B11. In addition, the receiving unit 30 joins the corresponding multicast in order to receive the multicast packet D1 transmitted from the terminal device P12.

An encapsulating unit 31 is connected to the receiving unit 30. In addition, a tunnel storage unit 32 is connected to the encapsulation unit 31. The tunnel storage unit 32 stores a tunnel setting table. The tunnel setting table is a list in which settings necessary for encapsulating or decapsulating multicast packets are described.

The encapsulating unit 31 adds the setting necessary for the encapsulation described in the tunnel setting table stored in the tunnel storage unit 32 to the multicast packet to generate an encapsulated multicast packet D2. The encapsulating unit 31 extracts the multicast packet D1 from the encapsulated multicast packet D2 received by the receiving unit 30 (decapsulation).

The encapsulation unit 31 sets the connection between the tunnel devices T11 and T12 by encapsulating or decapsulating the multicast packet (referred to as tunnel setting). For example,
When the terminal device P11 and a terminal device belonging to a network (not shown) other than the network N12 perform multicast communication, the network N11 and a network other than the network N12 need to perform tunnel setting based on the tunnel setting table.

A transmission unit 33 is connected to the encapsulation unit 31. The transmission unit 33 transmits the multicast packet D2 encapsulated by the encapsulation unit 31 via the router B11 via the bus B11.
Send to. The router R11 transmits the multicast packet D transmitted by the transmission unit 33.
2 to the network N12.

FIG. 7 is an explanatory diagram illustrating an operation example of the information transfer system 200. An example in which a multicast packet is transferred from the terminal device P11 to the terminal device P12 will be described. As shown in FIG. 7, the multicast packet D1 generated by the terminal device P11 is output to the tunnel device T11. The tunnel device T11 encapsulates the multicast packet D1 output from the terminal device P11 by adding a destination IP header or various extension headers described in the tunnel setting table, and encapsulates the multicast packet D2 in the router. Output to R11. The router R11 sends the multicast packet D output from the tunnel device T11.
2 is output to the router R12 via the Internet IN.

The router R12 outputs the multicast packet D2 output from the router R11 to the tunnel device T12. The tunnel device T12 decapsulates the multicast packet D2 output from the router R12 and extracts the multicast packet D1. Then, the tunnel device T12 transmits the decapsulated multicast packet D1 to the terminal device P1.
Output to 2. Thereby, the terminal device P12 converts the multicast packet D1 output from the terminal device P11 into the tunnel device T11, the router R11, the Internet IN, and the router R.
12 and the tunnel device T12.

JP 2009-118472 A

By the way, according to Patent Document 1 and the conventional information transfer system 200, there are the following problems when performing multicast communication.

i. One tunnel setting is necessary for one communication partner, and when there are many communication partners, the setting is very complicated.

ii. When multicast communication is performed between all networks, a full mesh tunnel must be set for each tunnel device.

iii. When a network for performing multicast communication is desired to be added, tunnel settings must be made for tunnel devices of all networks.

iv. Even when there is no reception of multicast communication, since multicast packets are transmitted, use of unnecessary traffic increases.

Therefore, the present invention solves such a problem, and multicast communication can be performed without performing complicated tunnel setting even when performing multicast communication with many communication partners or adding a network. It aims at providing the information transfer system which performs.

In order to solve the above-described problem, an information transfer system according to the present invention is an information transfer system in which a plurality of tunnel devices are connected to each other via a network and transfers multicast packets between the plurality of tunnel devices, When a list in which identifiers for identifying tunnel devices are described as an identifier list, the tunnel devices are connected to each other by a logically constructed tunnel network and are adjacent to the tunnel device in the tunnel network. And the tunnel device includes an identifier of the one tunnel device transmitted from the one tunnel device by requesting one adjacent tunnel device in the logical network to transmit the multicast packet. Receive identifier packet A signal unit, an identifier of said one of the tunnel devices included in the identifier packet received by the receiving unit, the identifier and the identifier list to describe list management unit of the tunnel device, said by the list management unit A packet generator that generates an identifier packet that includes the identifier of the tunnel device described in the identifier list, and a transmitter that transmits the identifier packet generated by the packet generator to another adjacent tunnel device in the tunnel network Are provided.

In the information transfer system according to the present invention, on the assumption that a plurality of tunnel devices are connected to each other via a network, when a list in which identifiers for identifying tunnel devices are described as an identifier list, An identifier packet including an identifier of another tunnel device transmitted from another tunnel device is received by requesting a multicast packet from another tunnel device, and the identifier of the other tunnel device included in the received identifier packet is an identifier list. The identifier packet including the identifier of the tunnel device described in the identifier list is generated, and the generated identifier packet is transmitted to another tunnel device. Thereby, the plurality of tunnel devices can recognize all the tunnel devices connected via the network with reference to the identifiers of the tunnel devices described in the identifier list.

According to the information transfer system of the present invention, since a plurality of tunnel devices connected via a network can recognize each other's other tunnel devices, other tunnel devices can be used when forwarding multicast packets to other tunnel devices. Can be transferred only to a desired tunnel device based on the identifier list in which the identifiers are described. As a result, it is possible to provide an information transfer system that performs multicast communication without performing complicated tunnel setting even when performing multicast communication with many communication partners or adding a network.

It is a block diagram which shows the structural example of the information transfer system 100 which concerns on this invention. It is a block diagram which shows the tunnel network example of tunnel apparatus T1, T2, T3. It is a block diagram which shows the structural example of tunnel apparatus T1. 6 is a sequence diagram illustrating an operation example of the information transfer system 100. FIG. It is a block diagram which shows the structural example of the conventional information transfer system. It is a block diagram which shows the structural example of tunnel apparatus T11. 6 is an explanatory diagram illustrating an operation example of the information transfer system 200. FIG.

Hereinafter, an information transfer system 100 according to an embodiment will be described with reference to the drawings.

<Configuration Example of Information Transfer System 100>
FIG. 1 is a block diagram showing a configuration example of an information transfer system 100 according to the present invention. FIG.
1, the information transfer system 100 includes a first terminal device (hereinafter referred to as a terminal device P1), a first router (hereinafter referred to as a router R1), and a first tunnel device (hereinafter referred to as a tunnel device T2). , A second terminal device (hereinafter referred to as terminal device P2), a second router (hereinafter referred to as terminal device P2).
Router R2), second tunnel device (hereinafter referred to as tunnel device T2), third terminal device (hereinafter referred to as terminal device P3), third router (hereinafter referred to as router R3), and third tunnel device. (Hereinafter referred to as tunnel device T3).

The terminal device P1, the router R1, and the tunnel device T1 are connected to each other via a bus B1, and constitute a first network (hereinafter referred to as a network N1). The terminal device P2, the router R2, and the tunnel device T2 are connected to each other via the bus B2.
A second network (hereinafter referred to as network N2) is configured. The terminal device P3, the router R3, and the tunnel device T3 are connected to each other via the bus B3, and constitute a third network (hereinafter referred to as a network N3). The network N1, the network N2, and the network N3 are connected via the Internet IN.

The terminal devices P1, P2, and P3 are terminal devices P11 provided in the conventional information transfer system 100.
, P12, for example, a mobile phone terminal or a notebook personal computer is used. The terminal devices P1, P2, and P3 generate a multicast packet used for multicasting, and transmit the multicast packet to the other terminal device via the Internet IN.

Routers R1, R2, and R3 are connected to networks N1, N2, and N via the Internet IN.
3 are connected to each other. For example, when the network N1 communicates with the network N2, communication is performed via the routers R1 and R2, and when the network N2 communicates with the network N3, the communication is performed via the routers R2 and R3. Is called.

The tunnel devices T1, T2, T3 encapsulate or decapsulate the multicast packets output from the terminal devices P1, P2, P3. For example, the tunnel device T1 is an example of an identifier packet including identifiers of the other tunnel devices T2 and T3 transmitted from the other tunnel devices T2 and T3 by requesting a multicast packet from the other tunnel devices T2 and T3. The listener management packet is received, and the identifiers of the other tunnel devices T2 and T3 included in the received listener management packet are described in a remote listener list which is an example of an identifier list, and the corresponding listener description is described in the remote listener list. A listener management packet including the identifier of the tunnel device T1 is generated, and the generated listener management packet is transmitted to the other tunnel devices T2 and T3.

Thereby, the plurality of tunnel devices T1, T2, T3 refer to the identifiers of the tunnel devices described in the listener management list, and all the tunnel devices T1, T2, T3 connected via the Internet IN are connected. Become able to recognize.

FIG. 2 is a block diagram illustrating a tunnel network example of the tunnel devices T1, T2, and T3. As shown in FIG. 2, the tunnel devices T1, T2, T3 are connected to the tunnel devices T1, T.
2 and T3 networks are logically constructed to recognize adjacent tunnel devices. (Tunnel devices T1, T2, and T3 are not physically connected by a cable or the like, but are connected through the Internet IN.) Between tunnel devices logically connected in such a network. Then, the listener management packet and the multicast packet are transferred.

<Configuration example of tunnel device T1>
Next, a configuration example of the tunnel device T1 will be described. FIG. 3 is a block diagram illustrating a configuration example of the tunnel device T1. As shown in FIG. 3, the tunnel device T1 includes a reception unit 10, a determination unit 11, an encapsulation unit 12, a transmission unit 13, a local listener management unit 14, a remote listener management unit 15, a tunnel setting unit 16, and a tunnel net management unit. 17. Local listener storage unit 18
A remote listener storage unit 19, a tunnel storage unit 20, and an adjacent tunnel device storage unit 21.

The receiving unit 10 receives various packets transmitted from other tunnel devices (for example, tunnel devices T2 and T3) via the bus B1. For example, for various packets, MLD (Multic
ast Listener Discovery (IGP) packets, Internet Group Management Protocol (IGMP)
Packets, listener management packets, tunnel setting packets, tunnel net management packets, unicast packets, multicast packets, and the like are included.

A listener management packet is a packet transmitted to notify a neighboring tunnel device that an entry has been added to or deleted from a local listener list, which is an example of an identifier list, such as a multicast address, a multicast and a tunnel device identifier, etc. Is included in the packet. The local listener list is a list indicating a list of multicast listeners existing in a network under the control of the own tunnel device. Based on this local listener list, for example, the neighboring tunnel devices T2 and T3 are notified that the tunnel device T1 is in a connected state. The entry of the local listener list includes a destination multicast address and the like.

The tunnel setting packet is a packet for requesting or responding to a tunnel device described in a remote listener list which is an example of an identifier list. The remote listener list is a list indicating a list of multicast addresses joined by other tunnel devices. Based on this remote listener list, whether or not multicast packets can be transferred and the destination of the tunnel device are determined.

The tunnel network management packet is a packet for updating a local listener list and a remote listener list that a neighboring tunnel device has, and is a packet including an identifier and an IP address of the tunnel device.

A determination unit 11 is connected to the reception unit 10. The determination unit 11 is connected to an encapsulation unit, a local listener management unit 14, a remote listener management unit 15, a tunnel setting unit 16, a tunnel net management unit 17, a remote listener storage unit 19, and a tunnel storage unit 20.
The determination unit 11 determines various packets received by the reception unit 10, and encapsulates the unit 12, the local listener management unit 14, the remote listener management unit 15, the tunnel setting unit 16, the tunnel net management unit 17, and the remote listener storage. The packet is output to the unit 19 and the tunnel storage unit 20.

When the packet output to the determination unit 11 is an MLD or IGMP packet, the determination unit 11 outputs the packet to the local listener management unit 14. When the packet output to the determination unit 11 is a listener management packet, the determination unit 11 outputs the packet to the remote listener management unit 15 and the remote listener storage unit 19. When the packet output to the determination unit 11 is a multicast packet and there are entries corresponding to the local listener list and the remote listener list stored in the local listener storage unit 18 and the remote listener storage unit 19 described later, the determination unit 11 Outputs the packet to the tunnel setting unit 16 and the tunnel storage unit 20.

When the packet output to the determination unit 11 is a tunnel setting packet, the tunnel setting unit 16
The packet is output to the tunnel storage unit 20. When the packet output to the determination unit 11 is a tunnel net management packet, the packet is output to the tunnel net management unit 17. When the packet output to the determination unit 11 is a unicast packet or a multicast packet and there is an entry corresponding to the tunnel setting, the packet is output to the encapsulation unit 12.

A local listener storage unit 18 is connected to the local listener management unit 14, and the local listener storage unit 18 stores a local listener list. The local listener management unit 14 processes the MLD or IGMP packet output by the determination unit 11 and writes or reads information included in the MLD or IGMP packet to the local listener list stored in the local listener storage unit 18. And perform maintenance. For example, when a new recipient appears due to an MLD or IGMP packet, the local listener management unit 14 adds a new entry to the local listener list, stores the addition in the listener management packet, and stores the listener. The management packet is output to the adjacent tunnel devices T2 and T3 via the transmission unit 13. In addition, when there are no recipients, the local listener management unit 14 deletes the corresponding entry in the local listener list, stores the deletion in the listener management packet, and stores the listener management packet in the adjacent listener list. The data is output to the tunnel devices T2 and T3 via the transmission unit 13.

A remote listener storage unit 19 is connected to the remote listener management unit 15, and the remote listener storage unit 19 stores a remote listener list. The remote listener management unit 15 processes the listener management packet output by the determination unit 11, and the remote listener storage unit 1
Maintenance is performed by writing or reading the information contained in the listener management packet in the remote listener list stored in FIG.

When the identifier of the tunnel device included in the received listener management packet does not include its own identifier, the remote listener management unit 15 adds or deletes an entry in the remote listener list and indicates that the listener has been added or deleted. The packet is stored in the management packet, and the listener management packet is output to the neighboring tunnel devices T2 and T3 via the transmission unit 13. In addition, the remote listener management unit 15 receives the multicast included in the listener management packet so that the tunnel device receives MLD or ID in the network to which the tunnel device is connected.
A GMP packet is used to join the corresponding multicast.

When the identifier of the tunnel device included in the received listener management packet includes its own identifier, the remote listener management unit 15 or the already existing tunnel devices T2, T3
When the same listener management packet is received from, the received listener management packet is discarded without being processed.

The tunnel setting unit 16 performs tunnel setting with the tunnel devices T2 and T3 based on the remote listener list when transferring the multicast packet to the tunnel devices T2 and T3.
The tunnel setting unit 16 sends another tunnel device T included in the corresponding remote listener entry.
2, a tunnel setting packet which is a packet indicating that a packet is requested to T3 is transmitted.

When the tunnel setting unit 16 receives a tunnel setting packet that is a packet indicating a response from the tunnel devices T2 and T3, the tunnel setting unit 16 determines that the tunnel setting is performed in the tunnel devices T2 and T3, and the tunnel for the corresponding multicast address Set up. When the tunnel setting unit 16 receives a tunnel setting packet indicating a request from the tunnel devices T2 and T3, the tunnel setting unit 16 performs tunnel setting based on a tunnel setting table stored in the tunnel storage unit 20 described later, and sends a response. The tunnel setting packet shown is transmitted to the tunnel devices T2 and T3 via the transmission unit 13.

A tunnel storage unit 20 is connected to the tunnel setting unit 16, and the tunnel storage unit 20
A tunnel setting table, which is a list in which settings necessary for encapsulating or decapsulating a multicast packet are described, is stored. The tunnel setting table stored in the tunnel storage unit 20 is written or read by the tunnel setting unit 16 and maintained.

The tunnel net management unit 17 performs maintenance of the local listener list and the remote listener list included in the tunnel devices T2 and T3 in order to construct the logical tunnel network shown in FIG. The tunnel net management unit 17 receives the tunnel net management packet output from the determination unit 11 and stores the information included in the received tunnel net management packet in the adjacent tunnel device storage unit 21 described later. Write to or read from the list to update the adjacent tunnel device list.

An adjacent tunnel device storage unit 21 is connected to the tunnel net management unit 17. The adjacent tunnel device storage unit 21 stores an adjacent tunnel device list. The adjacent tunnel device list is a list in which information on both adjacent tunnel devices T2 and T3 is described. The entry of the adjacent tunnel device list includes the identifier and IP address of the tunnel device.

The encapsulation unit 12 encapsulates or decapsulates various packets output by the determination unit 11 based on the tunnel setting table stored in the tunnel storage unit 20, and transmits the transmission unit 4.
Output to 0.

A transmission unit 40 is connected to the encapsulation unit 12, the local listener management unit 14, the remote listener management unit 15, the tunnel setting unit 16, and the tunnel net management unit 17. The transmission unit 40
Various packets output from the encapsulation unit 12, the local listener management unit 14, the remote listener management unit 15, the tunnel setting unit 16, and the tunnel net management unit 17 are transmitted to the tunnel devices T2 and T3 via the bus B1.

In the present embodiment, the configuration example of the tunnel device T1 has been described, but the tunnel devices T2 and T3 also have the same function and configuration.

<Operation Example of Information Transfer System 100>
Next, an operation example of the information transfer system 100 will be described. FIG. 4 is a sequence diagram illustrating an operation example of the information transfer system 100. As shown in FIG. 4, in step ST1, the terminal device P1 receives an MLD or an ILD in order to receive a multicast packet from the terminal device P2.
The GMP packet is transmitted to the tunnel device T1. Then, the tunnel device T1 receives the MLD or IGMP packet transmitted by the terminal device P1 at the reception unit 10, and the determination unit 11 determines that the received MLD or IGMP packet is an MLD or IGMP packet and performs local processing. The data is output to the listener management unit 14. The tunnel device T1 updates the local listener list stored in the local listener storage unit 18 based on the received MLD or IGMP packet.

In Step ST2, the tunnel device T1 transmits a listener management packet to the tunnel device T3 by the transmission unit 13 in order to notify that the multicast listener exists under the tunnel device T1. The tunnel device T3 receives the listener management packet transmitted from the tunnel device T1, and updates the remote listener list based on the received listener management packet.

In step ST3, as in step ST2, the tunnel device T1
2, the transmission unit 13 transmits a listener management packet. The tunnel device T2 receives the listener management packet transmitted from the tunnel device T1, and updates the remote listener list based on the received listener management packet.

In step ST4, the tunnel device T3 transfers the listener management packet received from the tunnel device T1 to the tunnel device T2.

In step ST5, the tunnel device T2 transfers the listener management packet received from the tunnel device T1 to the tunnel device T2.

As described above, since the listener management packet including the multicast address, the multicast and the identifier of the tunnel device is transferred to all the tunnel devices T1, T2, T3, the tunnel devices T1, T2, T3 By referring to the identifiers of the tunnel devices described in the remote listener list, all the tunnel devices T1, T2, T3 connected via the Internet IN can be recognized.

In Step ST6, the tunnel device T2 transmits an MLD or IGMP packet to the terminal device P2 in order to receive the multicast packet from the terminal device P2. Then, the terminal device P2 receives the MLD or IGMP packet transmitted from the tunnel device T2.

In Step ST7, the terminal device P2 transmits the multicast packet stored in the terminal device P2 to the tunnel device T2. The destination of this multicast packet is assumed to be the same destination as the multicast packet that the terminal device P1 desires to receive. Then, the tunnel device T2 receives the multicast packet transmitted by the terminal device P2.

Moving to step ST8, the tunnel device T2 searches the tunnel setting table stored in the tunnel setting unit to check whether or not the corresponding entry exists. In this case, since the multicast packet arrives first, there is no entry in the tunnel setting table. Therefore, the tunnel device T2 searches the remote listener list stored in the remote listener storage unit and confirms whether or not the corresponding entry exists. Since there is an entry received from the tunnel device T1 by updating the remote listener list in step ST3,
The tunnel device T2 transmits a tunnel setting packet indicating a request to the tunnel device T1.
Then, the tunnel device T1 receives the tunnel setting packet transmitted from the tunnel device T2, and updates its own tunnel setting table.

The process proceeds to step ST9, and when the tunnel device T1 finishes updating the tunnel setting table, the tunnel device T2 transmits a tunnel setting packet indicating a response to the tunnel device T2, thereby indicating that the tunnel setting table has been updated. Notify And the tunnel device T2
The tunnel setting packet transmitted from the tunnel device T1 is received, and it is determined that the update of the tunnel setting table of the tunnel device T1 is completed. Thereafter, the tunnel device T2 updates its tunnel setting table in the same manner as the tunnel device T1.

In Step ST10, when the tunnel device T2 finishes updating its own tunnel setting table, the tunnel device T2 encapsulates the multicast packet transmitted from the terminal device P2 based on the tunnel setting table and transmits it to the tunnel device T1. Then, the tunnel device T1 receives the encapsulated multicast packet transmitted by the tunnel device T2.

Moving to Step ST11, the tunnel device T1 searches the tunnel setting table stored in the tunnel storage unit 20, and determines whether or not the received multicast packet is encapsulated. As shown in step ST10, if the received multicast packet is encapsulated, tunnel device T1 decapsulates the encapsulated multicast packet and transmits it to terminal device P1. Tunnel device T
If the received multicast packet is not encapsulated, 1 transmits the multicast packet as it is to the terminal device P1. And the terminal device P1 is a tunnel device T.
The multicast packet transmitted from 1 is received.

As described above, according to the information transfer system 100 according to the present embodiment, the tunnel devices T1, T2, T3 are based on the assumption that the plurality of tunnel devices T1, T2, T3 are connected to each other via the Internet IN. When the list that describes the identifiers for identifying the remote listener list is used as the remote listener list, the tunnel device T1 requests other tunnel devices T2 and T3 to send multicast packets to the other tunnel devices T2 and T3. The listener management packet including the identifiers of the tunnel devices T2 and T3 is received, and the identifiers of the other tunnel devices T2 and T3 included in the received listener management packet are described in the remote listener list and described in the remote listener list. A listener management packet including the identifier of the tunnel device T1 T a listener management packet generated by the other tunnel device
2 and transmit to T3.

Thereby, the plurality of tunnel devices T1, T2, T3 recognize all the tunnel devices T1, T2, T3 connected via the Internet IN with reference to the identifiers of the tunnel devices described in the remote listener list. become able to.

As a result, the tunnel device T1 transmits the multicast packet to the other tunnel devices T2, T.
3 can be transferred only to a desired tunnel device based on a remote listener list in which identifiers of other tunnel devices T2 and T3 are described, and when performing multicast communication with many communication partners, Even when a network is added, multicast communication can be performed without complicated tunnel setting.

In the present embodiment, the operation example in which the tunnel device T1 requests a multicast packet from the other tunnel devices T2 and T3 has been described. However, the tunnel device T2 and T3 request the multicast packet from another tunnel device (tunnel device T2). The same operation is performed when the tunnel device T1, T3 requests, and when the tunnel device T3 requests the tunnel device T1, T2).

Further, although three tunnel devices have been described in the present embodiment, it is possible to perform multicast communication by connecting four or more tunnel devices. In other words, it is possible to connect more than 10,000 field devices used in a plant or the like, which has been difficult with the packet transfer method based on the routing table of a conventional router, to transfer the packets to each field device. This is possible by providing the tunnel device.

DESCRIPTION OF SYMBOLS 10,30 Reception part 11 Determination part 12,31 Encapsulation part 13,32 Transmission part 14 Local listener management part 15 Remote listener management part 16 Tunnel setting part 17 Tunnel net management part 18 Local listener storage part 19 Remote listener storage part 20, 32 Tunnel storage unit 21 Adjacent tunnel device storage unit 100, 200 Information transfer system T1 First tunnel device T2 Second tunnel device T3 Third tunnel device

Claims (5)

An information transfer system in which a plurality of tunnel devices are connected to each other via a network and transfers multicast packets between the plurality of tunnel devices,
When a list in which an identifier for identifying the tunnel device is described as an identifier list,
The tunnel devices are connected to each other by a logically constructed tunnel network, and recognize a tunnel device adjacent to the tunnel device in the logical network;
The tunnel device is
A receiving unit that receives an identifier packet including an identifier of the one tunnel device that is transmitted from the one tunnel device by requesting one adjacent tunnel device to transmit the multicast packet in the tunnel network ;
A list management unit that describes the identifier of the one tunnel device included in the identifier packet received by the reception unit and the identifier of the tunnel device in the identifier list;
A packet generation unit that generates an identifier packet including an identifier of the tunnel device described in the identifier list in the list management unit;
An information transfer system comprising: a transmission unit that transmits the identifier packet generated by the packet generation unit to another adjacent tunnel device in the tunnel network . A terminal device is connected to the tunnel device,
The terminal device
Generate a multicast packet and output it to the tunnel device,
The tunnel device is
The information transfer system according to claim 1, wherein the multicast packet output from the terminal device is transmitted to another tunnel device having the identifier described in the identifier list. When the terminal device requests reception of a desired multicast packet from another terminal device ,
The tunnel device is
Wherein the other of the tunnel device having an identifier the identifier list is described with sending tunnel configuration packet indicating a request for the reception, transmission of the multicast packet to the other of said other terminal device connected to the tunnel device The information transfer system according to claim 1, wherein the information transfer system is requested. An encapsulating unit is connected to the receiving unit,
The encapsulation unit is
4. The information transfer system according to claim 1, wherein the multicast packet is encapsulated or decapsulated. The transmission unit is connected to the encapsulation unit,
The transmitter is
5. The information transfer system according to claim 4 , wherein the multicast packet encapsulated by the encapsulation unit is transmitted to another tunnel device having the identifier described in the identifier list.

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