JP2010251918A - Communication network system, and communication control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce cost concerning network construction in a communication network system for electric power. <P>SOLUTION: The communication network system for the electric power is constructed of only a layer 2 switch. Therefore, an edge switch connected to a private network memorizes definition information whether or not a VLAN installed in the private network which the apparatus itself accommodates communicates over a plurality of private networks. Moreover, when the edge switch receives a frame from the private network which the apparatus itself accommodates, the edge switch discriminates whether or not the received frame is transmitted from the VLAN performing communications over the plurality of the private networks based on the memorized definition information. The edge switch transfers only frames which is discriminated to be ones transmitted from the VLAN which performs communications over the plurality of the private networks to a wide area network. Consequently, it makes possible to assign VLAN ID overlapping for the plurality of the private networks. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a communication network system and a communication control method including a plurality of local networks, a wide area network that accommodates each local area network, and a relay device that relays communication performed between the local area network and the wide area network. .

  Conventionally, in the field of electric power business, electric power communication networks connecting electric power bases and facilities are used. The power communication network is a large-scale communication network having a plurality of local networks provided for each base or facility and a wide area network connecting the local networks via a relay device. In such power communication networks, in recent years, introduction of IP (Internet Protocol) technology having excellent versatility has been promoted.

  Generally, a communication network to which IP technology is applied is constructed using Ethernet (registered trademark) technology. However, the Ethernet (registered trademark) technology is a technology assumed to be used in a small-scale communication network such as a private network, and is applied to a wide area network of a large-scale communication network such as a power communication network. Has a problem with scalability.

  For example, in a power communication network, a VLAN (Virtual Local Area Network) is set for each application or department in a private network, but Ethernet (registered trademark) has an upper limit on the number of VLANs that can be set. . Specifically, in Ethernet (registered trademark), a VLAN is identified by a VLAN ID set in a frame. Therefore, when an electronic communication network is constructed by Ethernet (registered trademark), a network is provided for each VLAN. It is necessary to assign a VLAN ID that is unique throughout. However, the VLAN ID in Ethernet (registered trademark) is a value represented by a 12-bit area, and all “0” and all “1” cannot be set. Therefore, the maximum number of VLAN IDs that can be set by Ethernet (registered trademark), that is, the number of VLANs is 4,094 at the maximum.

  Due to such problems, conventionally, when building a power communication network using Ethernet (registered trademark) technology, scalability has been ensured by using an IP router (see, for example, Non-Patent Document 1). Specifically, by physically dividing the network, a VLAN ID is set independently in each network, and communication between networks is performed via an IP router.

“Non-stop Integrated IP MPLS Network”, Juniper Networks, Inc. [Search February 19, 2009], Internet <URL: http://www.juniper.co.jp/solutions/customer_case_studies/Tohoku/Tohoku. pdf>

  However, in general, an IP router is more expensive than a layer 2 switch or the like. Therefore, when a power communication network is constructed using an IP router, there is a problem that the cost for constructing the network increases. In recent years, the electric power industry has entered an era of competition due to the liberalization of electric power, and further cost reduction is required to win the competition. Therefore, when building a power communication network using IP technology, how to build a network at a low cost is an important issue. This problem occurs not only in the power communication network system but also in a large-scale communication network system in which a large number of VLANs are set.

  The present invention has been made in view of the above, and an object of the present invention is to provide a communication network system and a communication control method capable of reducing the cost of network construction.

  In order to solve the above-described problems and achieve the object, the present invention relays communications performed between a plurality of local networks, a wide area network accommodating each local area network, and the local area network and the wide area network. A relay network device, wherein the relay device is a layer 2 switch.

  Further, the present invention is the above invention, wherein the relay device indicates whether or not a virtual network set in a local network accommodated by the relay device communicates across a plurality of local networks. Definition information storage means for storing definition information, frame reception means for receiving a frame from a local network accommodated by the device itself, and storage by the definition information storage means when the frame reception means receives the frame. Based on the defined definition information, transfer determination means for determining whether or not the frame is transmitted from a virtual network that communicates across a plurality of local networks, and a plurality of local areas by the transfer determination means Frame transfer for transferring only frames determined to be transmitted from a virtual network that communicates across a network to the wide area network Characterized by comprising a stage.

  A communication control method applied to a communication network system having a plurality of local networks, a wide area network that accommodates each local area network, and a relay device that relays communication performed between the local area network and the wide area network. The relay device is a layer 2 switch, and the relay device receives a frame from a private network accommodated by the relay device; and the relay device receives the frame when the frame is received. Referring to the storage unit storing the definition information indicating whether or not the virtual network set in the local network accommodated by the mobile station communicates across multiple local networks, the frame is Determining whether or not the transmission is from a virtual network that communicates across a plurality of local networks; and the virtual network in which the relay device communicates across a plurality of local networks Only frames determined to be sent from over click, characterized in that it includes a step of transferring to the wide area network.

  According to the present invention, in a large-scale communication network system in which a plurality of VLANs are set, it is possible to reduce the cost for network construction.

FIG. 1 is a diagram illustrating the overall configuration of the power communication network system according to the first embodiment. FIG. 2 is a diagram illustrating an example of definition information stored by the edge switch according to the first embodiment. FIG. 3 is a functional block diagram illustrating the configuration of the edge switch according to the first embodiment. FIG. 4 is a diagram illustrating an example of a format of a local area network frame according to the first embodiment. FIG. 5 is a diagram illustrating an example of the format of the wide area network frame according to the first embodiment. FIG. 6 is a flowchart illustrating the flow of frame transfer performed by the edge switch 20a connected to the wide area network according to the first embodiment. FIG. 7 is a diagram illustrating the overall configuration of the power communication network system according to the second embodiment. FIG. 8 is a diagram illustrating an example of definition information stored by the edge switch connected to the access network according to the second embodiment. FIG. 9 is a diagram illustrating an example of the wide area definition information stored by the edge switch connected to the backbone network according to the second embodiment. FIG. 10 is a functional block diagram illustrating the configuration of the edge switch 80a connected to the backbone network according to the second embodiment. FIG. 11 is a diagram illustrating an example of a format of a backbone network frame according to the second embodiment. FIG. 12 is a flowchart illustrating the flow of frame transfer performed by the edge switch connected to the backbone network according to the second embodiment.

  Embodiments of a communication network system and a communication control method according to the present invention will be described below in detail with reference to the drawings. In the following embodiments, the case where the present invention is applied to a power communication network system will be described. However, the present invention is not limited to the embodiments described here.

  First, the overall configuration of the power communication network system according to the first embodiment will be described. FIG. 1 is a diagram illustrating the overall configuration of the power communication network system according to the first embodiment. As illustrated in FIG. 1, the power communication network system according to the first embodiment includes a plurality of terminal devices 10 a to 10 g, a plurality of edge switches 20 a to 20 c, and a relay switch 30.

  The terminal devices 10a to 10g are installed at power bases and facilities, respectively, and are connected to the edge switches 20a to 20c via the local networks 1a to 1d. Specifically, the terminal devices 10a and 10b are connected to the edge switch 20a via the local area network 1a. The terminal device 10c is connected to the edge switch 20a via the local area network 1b. The terminal devices 10d and 10e are connected to the edge switch 20b via the local area network 1c. The terminal devices 10f and 10g are connected to the edge switch 20c via the local area network 1d.

  The edge switches 20a to 20c are connected to the wide area network 2 and accommodate the local networks 1a to 1d. Specifically, the edge switch 20a accommodates the local networks 1a and 1b, the edge switch 20b accommodates the local network 1c, and the edge switch 20c accommodates the local network 1d. The relay switch 30 is connected to the wide area network 2 and accommodates the edge switches 20a to 20c.

  Here, each of the edge switches 20a to 20c and the relay switch 30 is a layer 2 switch capable of communication by Ethernet (registered trademark). In the first embodiment, each switch forwards an Ethernet (registered trademark) frame via the local networks 1 a to 1 d and the wide area network 2. Specifically, the edge switch 20a transfers the frame via the local network 1a, the local network 1b, and the wide area network 2, and the edge switch 20b transfers the frame via the local area network 1c and the wide area network 2, The switch 20c transfers the frame via the local area network 1d and the wide area network 2. Further, the relay switch 30 transfers a frame via the wide area network 2.

  Furthermore, in the power communication network system according to the first embodiment, a plurality of VLANs for connecting the terminal devices connected to the local networks 1a to 1d are set. Specifically, VLANs are set between the terminal device 10a and the terminal device 10b, between the terminal device 10c, the terminal device 10d, and the terminal device 10g, and between the terminal device 10e and the terminal device 10f, respectively. . Each VLAN is set for each application to which the terminal devices 10a to 10g are installed and each department to which the terminal devices 10a to 10g belong.

  Each VLAN is assigned a first VLAN ID for identifying the VLAN in the local network. This first VLAN ID is hereinafter referred to as “C-VID”. For example, a VLAN set between the terminal device 10a and the terminal device 10b is assigned “20” as the C-VID. Further, “100” is assigned as the C-VID to the VLAN set between the terminal device 10c, the terminal device 10d, and the terminal device 10g. Further, “10” is assigned as C-VID to the VLAN set between the terminal device 10e and the terminal device 10f.

  Under such a configuration, in the power communication network system according to the first embodiment, the edge switches 20a to 20c connected to the wide area network 2 are set to the private network accommodated by the own device. Definition information indicating whether each VLAN communicates across a plurality of local networks is stored.

  FIG. 2 is a diagram illustrating an example of definition information stored by the edge switches 20a to 20c according to the first embodiment. As shown in FIGS. 2A to 2C, specifically, the edge switches 20a to 20c store information associating S-VID and C-VID for each VLAN as definition information. Here, “S-VID” is a second VLAN ID for identifying each VLAN set in the local networks 1 a to 1 d in the wide area network 2.

  For example, as shown in FIG. 2A, when S-VID: “100” and C-VID: “100” are associated with each other, the VLAN with C-VID: “100” is This indicates that communication is performed across a plurality of local networks, and that the VLAN is identified by S-VID: “100” in the wide area network 2. On the other hand, as shown in FIG. 2A, when the S-VID corresponding to C-VID: “10” is undefined, there are a plurality of VLANs with C-VID: “10”. This indicates that communication is not performed across the local area network.

  When the edge switches 20a to 20c receive a frame from the local network accommodated by the device, the edge switches 20a to 20c perform communication across the multiple local networks based on the stored definition information. It is determined whether or not the transmission is from a VLAN to be performed. Subsequently, the edge switches 20 a to 20 c transfer only the frame determined to be transmitted from the VLAN that performs communication across a plurality of local networks to the wide area network 2.

  Here, the concept of frame transfer in the power communication network system according to the first embodiment will be described with reference to FIGS. 1 and 2. For example, in FIG. 1, the edge switch 20a stores the definition information shown in FIG. 2A, the edge switch 20b stores the definition information shown in FIG. 2B, and the edge switch 20c It is assumed that the definition information shown in (c) of 2 is stored.

  For example, assume that the terminal device 10a transmits a frame to the local area network 1a. In this case, the frame transmitted to the local network 1a is transferred to the terminal device 10b and the edge switch 20a. When the frame is transferred from the local network 1a, the edge switch 20a has an undefined S-VID corresponding to C-VID: “20” in the stored definition information ((a in FIG. 2). The received frame is not transferred to the wide area network 2.

  In this way, communication closed within the local network 1a is performed between the terminal device 10a and the terminal device 10b. That is, by setting the definition information as shown in FIG. 2, in the VLAN set between the terminal device 10a and the terminal device 10b, it becomes possible to perform closed communication between both terminal devices.

  For example, assume that the terminal device 10d transmits a frame to the local area network 1c. In this case, the frame transmitted to the local network 1c is transferred to the terminal device 10e and the edge switch 20b. When the frame is transferred from the local network 1c, the edge switch 20b has the S-VID corresponding to C-VID: “100” in the stored definition information as “100” ((( b)), the received frame is transferred to the wide area network 2. The frame transferred to the wide area network 2 is transferred to the edge switches 20a and 20c via the relay switch 30.

  When the frame is transferred from the relay switch 30, the edge switch 20 a has the C-VID corresponding to S-VID: “100” in the stored definition information as “100” (in FIG. 2 ( a), and the transferred frame is transmitted to the terminal device 10c. On the other hand, when the frame is transferred from the relay switch 30, the edge switch 20c has the C-VID corresponding to S-VID: “100” in the stored definition information as “100” (FIG. 2). The transferred frame is transmitted to the terminal device 10g.

  Thus, communication is performed between the terminal devices 10a, 10c, and 10g via the local networks 1b, 1c, and 1d. That is, by setting the definition information as shown in FIG. 2, it is possible to communicate with the VLAN set between the terminal device 10c, the terminal device 10d, and the terminal device 10g.

  As described above, in the first embodiment, when the edge switches 20a to 20c receive frames from the local networks 1a to 1d, a plurality of frames are received based on the definition information stored therein. It is determined whether or not it is from a VLAN that performs communication across the local network. The edge switches 20a to 20c transfer only frames transmitted from the VLAN that performs communication across a plurality of local networks to the wide area network 2. In other words, the edge switches 20a to 20c do not transfer a frame from a VLAN that performs communication closed to one local network to the wide area network 2.

  From this, in the first embodiment, when there are a plurality of VLANs that perform closed communication in one local network, it is possible to assign the same VLAN ID (C-VID) to each VLAN redundantly. . Therefore, according to the first embodiment, the number of VLANs exceeding the upper limit number of VLAN IDs that can be set by Ethernet (registered trademark) can be set. Therefore, since the power communication network system according to the first embodiment can be constructed using only the layer 2 switch capable of communication using Ethernet (registered trademark), the cost for constructing the network can be reduced. Is possible.

  Next, the configuration of the edge switches 20a to 20c according to the first embodiment will be described. Since the edge switches 20a to 20c have the same configuration, the edge switch 20a will be described as an example here. In the following, the frames transferred in the local networks 1a to 1d are referred to as “local network frames”, and the frames transferred in the wide area network 2 are referred to as “wide area network frames”.

  FIG. 3 is a functional block diagram illustrating the configuration of the edge switch 20a according to the first embodiment. As shown in FIG. 3, the edge switch 20 a includes a MAC address table 21, a VID conversion table 22, a private network frame transmission / reception unit 23, a wide area network frame transmission / reception unit 24, and a frame processing unit 25.

  Here, before describing each part of the edge switch 20a, the formats of the private network frame and the wide area network frame will be described.

  FIG. 4 is a diagram illustrating an example of a format of a local area network frame according to the first embodiment. As shown in FIG. 4, the local area network frame includes, for example, “destination address”, “source address”, “first tag information”, “length / type”, as areas in which various values are set. It has “user data” and “FCS (Frame Check Sequence)”. This format is a general Ethernet (registered trademark) frame format.

  The destination address is an area in which the MAC address of the terminal device that is the transmission destination of the local area network frame is set. The transmission source address is an area in which the MAC address of the terminal device that is the transmission source of the private network frame is set. The length / type is an area in which identification information for identifying a length of user data or an upper layer protocol set in the user data is set. The FCS is an area in which a CRC (Cyclic Redundancy Check) value for detecting an error in the local network frame is set.

  The first tag information is an area in which various information for performing processing related to the VLAN in the local area network is set. The information set in the first tag information includes C-VID for identifying the VLAN in the local network.

  FIG. 5 is a diagram illustrating an example of the format of the wide area network frame according to the first embodiment. As shown in FIG. 5, the wide area network frame includes, for example, “destination address”, “source address”, “second tag information”, and “first tag information” as areas in which various values are set. , “Length / type”, “user data”, and “FCS (Frame Check Sequence)”.

  Of these areas, areas other than the second tag information are basically the same as the areas of the same name included in the local area network frame shown in FIG. That is, the destination address and the source address have the same format as the destination address and the source address of the private network frame shown in FIG. Therefore, the wide area network frame can be transferred by Ethernet (registered trademark) in the same manner as the local area network frame shown in FIG.

  The second tag information is an area in which various information for performing various processes related to the VLAN in the wide area network is set. The information set in the second tag information includes S-VID for identifying the VLAN in the wide area network. The S-VID has the same format as the C-VID of the private network frame shown in FIG.

  Returning to the description of FIG. 3, the MAC address table 21 shows the MAC (Media Access Control) address of the terminal device connected to the edge switch 20a and the output port to which the terminal device having the MAC address is connected. It is the table which matched. The MAC address table 21 is updated by a MAC address table update unit (not shown). Specifically, the MAC address table update unit uses the transmission source address of the local network frame received from the local networks 1a and 1b and the transmission source address of the wide area network frame received from the wide area network 2 to use the MAC address table. 21 is updated.

  The VID conversion table 22 stores definition information indicating whether or not a VLAN set in a local network accommodated by the edge switch 20a communicates across a plurality of local networks. Specifically, as shown in FIG. 2, the VID conversion table 22 stores information associating S-VID and C-VID for each VLAN as definition information.

  The local network frame transmission / reception unit 23 controls transmission / reception of local network frames exchanged between the local networks 1a and 1b. Specifically, when receiving the local network frame from the local network 1 a or 1 b, the local network frame transmitting / receiving unit 23 transfers the received local network frame to the frame processing unit 25. In addition, when the local network frame is transferred from the frame processing unit 25, the local network frame transmitting / receiving unit 23 refers to the MAC address table 21 and sets an output port corresponding to the destination address of the transferred local network frame. Identify. Then, the local area network frame transmitting / receiving unit 23 transmits the local area network frame to the local area network 1a or 1b via the specified output port.

  The wide area network frame transmission / reception unit 24 controls transmission / reception of wide area network frames exchanged with the wide area network 2. Specifically, when receiving a wide area network frame from the wide area network 2, the wide area network frame transmission / reception unit 24 transfers the received wide area network frame to the frame processing unit 25. In addition, when the wide area network frame is transferred from the frame processing unit 25, the wide area network frame transmitting / receiving unit 24 refers to the MAC address table 21 and sets an output port corresponding to the destination address of the transferred wide area network frame. Identify. Then, the frame processing unit 25 transmits the wide area network frame to the wide area network 2 via the specified output port.

  The frame processing unit 25 generates a local area network frame and a wide area network frame based on the definition information registered in the VID conversion table 22. Specifically, the frame processing unit 25 generates a wide area network frame from the local network frame transferred from the local network frame transmitting / receiving unit 23. The frame processing unit 25 generates a local area network frame based on the wide area network frame transferred from the wide area network frame transmitting / receiving unit 24. The processing performed by the frame processing unit 25 will be described in detail in the frame transfer flow described below.

  Next, a flow of frame transfer performed by the edge switch 20a connected to the wide area network 2 according to the first embodiment will be described. FIG. 6 is a flowchart illustrating the flow of frame transfer performed by the edge switch 20a connected to the wide area network 2 according to the first embodiment.

  As shown in FIG. 6, in the edge switch 20a, when the local network frame transmitting / receiving unit 23 receives the local network frame (step S101, Yes), the frame processing unit 25 refers to the VID conversion table 22 (step S101). S102), it is confirmed whether or not an S-VID corresponding to the C-VID of the received local network frame is defined (step S103).

  Here, when the S-VID is defined (step S104, Yes), the frame processing unit 25 inserts the S-VID corresponding to the C-VID of the received local network frame into the local network frame. Thus, a wide area network frame is generated (step S105). Then, the frame processing unit 25 transfers the generated wide area network frame to the wide area network 2 via the wide area network frame transmitting / receiving unit 24 (step S106).

  If the S-VID corresponding to the C-VID of the received local network frame is not defined (No in step S104), the frame processing unit 25 discards the received local network frame (step S107). ).

  On the other hand, when the local area network frame transmission / reception unit 23 has received the wide area network frame (step S108, Yes), the frame processing unit 25 refers to the VID conversion table 22 (step S109), and the received local area network frame C It is confirmed whether or not the S-VID corresponding to the VID is defined (step S110).

  If the S-VID has been defined (step S111, Yes), the frame processing unit 25 deletes the S-VID from the received wide area network frame to generate a local area network frame (step S111). S112). Then, the frame processing unit 25 transfers the generated local network frame to the local network 1a or 1b via the local network frame transmission / reception unit 23 (step S113).

  If the S-VID corresponding to the C-VID of the received wide area network frame is not defined (No at Step S111), the frame processing unit 25 discards the received wide area network frame (Step S114). ).

  As described above, in the first embodiment, each of the edge switches 20a to 20c and the relay switch 30 is a layer 2 switch capable of communication using Ethernet (registered trademark).

  Therefore, according to the first embodiment, in the power communication network system, it is possible to reduce the cost for constructing the network system.

  Further, in the first embodiment, in the edge switches 20a to 20c, the VLAN set in the local network accommodated by the VID conversion table 22 is communicated across a plurality of local networks. Definition information indicating whether or not is stored. Further, the local network frame transmission / reception unit 23 receives a frame from the local network accommodated by the local apparatus. When a frame is received by the local network frame transmission / reception unit 23, the frame processing unit 25 determines that the received frame crosses a plurality of local networks based on the definition information stored in the VID conversion table 22. It is determined whether or not the transmission is from a VLAN that performs communication. Further, the frame processing unit 25 transfers only the frame determined to be transmitted from the VLAN that performs communication across a plurality of local networks to the wide area network via the wide area network frame transmitting / receiving unit 24.

  Therefore, according to the first embodiment, when there are a plurality of VLANs that perform closed communication in one local network, it is possible to assign the same VLAN ID (C-VID) to each VLAN in an overlapping manner. . Therefore, according to the first embodiment, the number of VLANs exceeding the upper limit number of VLAN IDs that can be set by Ethernet (registered trademark) can be set.

  In the first embodiment, in the edge switches 20a to 20c, the VID conversion table 22 uses the C-VID for identifying the VLAN in the local network and the wide area network for the VLAN that communicates across the plurality of local networks. The information associated with the S-VID for identifying the VLAN is stored as definition information. When the frame processing unit 25 associates the S-VID with the C-VID set in the frame received by the local network frame transmission / reception unit 23, the frame spans a plurality of local networks. It is determined that the transmission is from a VLAN that performs communication.

  Therefore, according to the first embodiment, the frame transfer in the wide area network 2 can be controlled only by storing the information in which the C-VID and the S-VID are associated with each other in the edge switches 20a to 20c. A network can be easily constructed.

  By the way, in the first embodiment described above, the same C-VID can be assigned to different VLANs for VLANs that perform closed communication in one local network. It is possible to set the number of C-VIDs exceeding the upper limit number of VLAN IDs that can be set by (registered trademark). However, S-VID for identifying VLANs in a wide area network cannot be set to a number exceeding the upper limit number of VLAN IDs in Ethernet (registered trademark).

  Thus, for example, the upper limit number of S-VIDs may be increased by further hierarchizing the power communication network system described in the first embodiment. Hereinafter, a case where the power communication network system is further hierarchized will be described as a second embodiment. In the second embodiment described below, a case where the wide area network is configured with two layers of an access network and a backbone network will be described.

  First, the overall configuration of the power communication network system according to the second embodiment will be described. FIG. 7 is a diagram illustrating the overall configuration of the power communication network system according to the second embodiment. As illustrated in FIG. 7, the power communication network system according to the second embodiment includes servers 40a and 40b, data terminals 50a and 50b, terminal devices 60a to 60d, edge switches 70a to 70d, edge switches 80a and 80b, and relays. And a switch 90.

  The servers 40a and 40b, the data terminals 50a and 50b, and the terminal devices 60a to 60d are installed in power bases and facilities, respectively, and are connected to the edge switches 70a to 70d via the local networks 3a to 3d. . Specifically, the server 40a and the terminal device 60a are connected to the edge switch 70a via the local area network 3a. The terminal device 60b and the data terminal 50a are connected to the edge switch 70b via the local area network 3b. The data terminal 50b and the terminal device 60c are connected to the edge switch 70c via the local area network 3c. The terminal device 60d and the server 40b are connected to the edge switch 70d via the local area network 3d.

  The edge switches 70a and 70b are respectively connected to the access network 4a and accommodate the local networks 3a and 3b. The edge switches 70c and 70d are respectively connected to the access network 4b and accommodate the local networks 3c and 3d. Specifically, the edge switch 70a accommodates the local network 3a, and the edge switch 70b accommodates the local network 3b. The edge switch 70c accommodates the local network 3c, and the edge switch 70d accommodates the local network 3d.

  The edge switches 80a and 80b are connected to the backbone network 5 and accommodate the access networks 4a and 4b. Specifically, the edge switch 80a accommodates the access network 4a, and the edge switch 80b accommodates the access network 4b. The relay switch 90 is connected to the backbone network 5 and accommodates edge switches 80a and 80b.

  Here, the edge switches 70a to 70d, the edge switches 80a and 80b, and the relay switch 90 are layer 2 switches that can communicate with each other by Ethernet (registered trademark). In the second embodiment, each switch transfers an Ethernet (registered trademark) frame via the local networks 3 a to 3 d, the access networks 4 a and 4 b, and the backbone network 5.

  Specifically, the edge switch 70a transfers the frame via the local network 3a and the access network 4a, and the edge switch 70b transfers the frame via the local network 3b and the access network 4a. The edge switch 70c transfers the frame via the local network 3c and the access network 4b, and the edge switch 70d transfers the frame via the local network 3d and the access network 4b. Further, the edge switch 80a transfers a frame via the access network 4a and the backbone network 5, and the edge switch 80b transfers a frame via the access network 4b and the backbone network 5. Further, the relay switch 90 transfers the frame via the backbone network 5.

  Furthermore, in the power communication network system according to the second embodiment, a plurality of VLANs that connect the devices connected to the local networks 3a to 3d are set. Specifically, VLANs for equipment maintenance data collection are set between the server 40a and the data terminal 50a, between the server 40b and the data terminal 50b, and respectively. Further, main protection VLANs are set between the terminal device 60a and the terminal device 60b and between the terminal device 60c and the terminal device 60d, respectively. Each VLAN is set for each department to which the servers 40a and 40b, the data terminals 50a and 50b, the applications installed in the terminal devices 60a to 60d and the terminal devices 10a to 10g belong.

  Each VLAN is assigned a C-VID for identifying the VLAN in the local network. For example, the equipment maintenance data collection VLAN set between the server 40a and the data terminal 50a is assigned “100” as the C-VID. In addition, “200” is set as the C-VID in the equipment maintenance data collection VLAN set between the server 40b and the data terminal 50b. Further, in the main protection VLAN set between the terminal device 60a and the terminal device 60b, “20” is set as the C-VID, and is set between the terminal device 60c and the terminal device 60d. The main protection VLAN is also assigned “20” as the C-VID.

  Under such a configuration, in the power communication network system according to the second embodiment, the edge switches 70a to 70d connected to the access networks 4a and 4b are set to the private network accommodated by the own device. Definition information indicating whether each VLAN communicates across a plurality of local networks is stored.

  FIG. 8 is a diagram illustrating an example of definition information stored by the edge switches 70a to 70d connected to the access networks 4a and 4b according to the second embodiment. As shown in FIGS. 8A and 8B, specifically, the edge switches 70a to 70d store information associating S-VIDs and C-VIDs as definition information for each VLAN. In the second embodiment, “S-VID” is a VLAN ID for identifying each VLAN set in the local networks 3a to 3d in the access networks 4a and 4b.

  For example, as shown in FIG. 8A, when S-VID: “10” and C-VID: “20” are associated with each other, the VLAN with C-VID: “10” is This indicates that communication is performed across a plurality of local networks, and that the VLAN is identified by S-VID: “10” in the access networks 4a and 4b.

  When the edge switches 70a to 70d receive a frame from the local network accommodated by the own device, the received frames communicate with each other across a plurality of local networks based on the stored definition information. It is determined whether or not the transmission is from a VLAN to be performed. Subsequently, the edge switches 70a and 70b transfer only the frame determined to be transmitted from the VLAN that performs communication across a plurality of local networks to the access network 4a. On the other hand, the edge switches 70c and 70d transfer only the frame determined to be transmitted from the VLAN that performs communication across a plurality of local networks to the access network 4b.

  Further, in the power communication network system according to the second embodiment, the edge switches 80a and 80b connected to the backbone network 5 are configured so that the VLAN via the access network accommodated by the own device spans a plurality of access networks. Wide area definition information indicating whether or not communication is performed is stored.

  FIG. 9 is a diagram illustrating an example of the wide area definition information stored by the edge switches 80a and 80b connected to the backbone network 5 according to the second embodiment. As shown in (a) and (b) of FIG. 9, specifically, the edge switches 80a and 80b each set information that associates an I-SID and an S-VID as wide area definition information for each VLAN. Remember. Here, “I-SID” is a third VLAN ID for identifying the VLAN in the backbone network 5.

  For example, as shown in FIG. 9A, when I-SID: “200” and S-VID: “20” are associated with each other, the VLAN of I-SID: “200” is This indicates that communication is performed across a plurality of access networks, and in the backbone network 5, that VLAN is identified by I-SID: “200”. On the other hand, as shown in FIG. 9A, when the I-SID corresponding to S-VID: “10” is undefined, there are a plurality of VLANs with S-VID: “10”. This indicates that communication is not performed across access networks.

  When the edge switches 80a and 80b receive a frame from the access network accommodated by the own device, the received frames are communicated across a plurality of access networks based on the stored wide area definition information. It is determined whether or not it is transmitted from the VLAN that performs the above. Subsequently, the edge switches 80 a and 80 b transfer only the frame determined to be transmitted from the VLAN that performs communication across a plurality of access networks to the backbone network 5.

  Here, the concept of frame transfer in the power communication network system according to the second embodiment will be described with reference to FIG. 7, FIG. 8, and FIG. For example, in FIG. 7, the edge switches 70a and 70b store the definition information shown in FIG. 8A, and the edge switches 70c and 70d store the definition information shown in FIG. 8B. . Assume that the edge switch 80a stores the definition information shown in FIG. 9A, and the edge switch 80b stores the definition information shown in FIG. 9B.

  For example, it is assumed that the terminal device 60a transmits a frame to the local area network 3a. In that case, the frame transmitted to the local area network 3a is transferred to the edge switch 70a. When the frame is transferred from the local area network 3a, the edge switch 70a has the S-VID corresponding to C-VID: “20” in the stored definition information as “10” ((( a), the received frame is transferred to the access network 4a. The frame transferred to the access network 4a is transferred to the edge switch 80a and the edge switch 70b.

  When the frame is transferred from the access network 4a, the edge switch 80a has an undefined I-SID corresponding to S-VID: “10” in the stored wide area definition information (( a)), the received frame is not transferred to the backbone network 5. On the other hand, when the frame is transferred, the edge switch 70b has the C-VID corresponding to S-VID: “10” in the stored wide area definition information “20” ((a in FIG. 8). And the received frame is transferred to the terminal device 60b.

  In this way, communication closed within the access network 4a is performed between the terminal device 60a and the terminal device 60b. That is, by setting the definition information and the wide area definition information as shown in FIGS. 8 and 9, the main protection VLAN set between the terminal device 60a and the terminal device 60b is closed between both terminal devices. Will be able to communicate.

  For example, it is assumed that the data terminal 50a transmits a frame to the local area network 3b. In that case, the data transmitted to the local area network 3b is transferred to the edge switch 70b. When the frame is transferred from the local area network 3b, the edge switch 70b has the S-VID corresponding to C-VID: “100” in the stored definition information as “20” ((a in FIG. 8 And the received frame is transferred to the access network 4a. The frame transferred to the access network 4a is transferred to the edge switch 70a and the edge switch 80a.

  When the frame is transferred from the access network 4a, the edge switch 70a has the C-VID corresponding to S-VID: “20” in the stored wide area definition information as “100” (FIG. 8). (See (a)), the received frame is transferred to the server 40a.

  On the other hand, when the frame is transferred from the access network 4a, the edge switch 80a has the I-SID corresponding to S-VID: “20” in the stored wide area definition information as “200” (see FIG. 9 (a)), the received frame is transferred to the backbone network 5. The frame transferred to the backbone network 5 is transferred to the edge switch 80b via the relay switch 90.

  When the frame is transferred from the relay switch 90, the edge switch 80b has the S-VID corresponding to the I-SID: “200” in the stored wide area definition information “100” (FIG. 9). (See (b)), the transferred frame is transferred to the access network 4b. The frame transferred to the access network 4b is transferred to the edge switches 70c and 70d.

  When the frame is transferred from the access network 4b, the edge switch 70c has a C-VID corresponding to S-VID: “100” in the stored wide area definition information “200” (FIG. 8). (See (b)), the received frame is transferred to the data terminal 50b. On the other hand, when the frame is transferred, the edge switch 70d has the C-VID corresponding to S-VID: “100” in the stored wide area definition information “200” (FIG. 8B). And the received frame is transferred to the server 40b.

  Thus, communication is performed between the data terminal 50a, the server 40a, the data terminal 50b, and the server 40b via the access networks 4a and 4b and the backbone network 5. That is, by setting the definition information and the wide area definition information as shown in FIG. 8 and FIG. 9, the facility maintenance data collection VLAN set between the data terminal 50a and the server 40a, the data terminal 50b, Communication can be performed with the facility maintenance data collection VLAN set with the server 40b.

  As described above, in the second embodiment, when the edge switches 70a to 70d receive frames from the local network, the received frames are transferred to a plurality of local networks based on the stored definition information. It is determined whether or not the VLAN is one that communicates across the network. The edge switches 70a to 70d transfer only the frames transmitted from the VLAN that performs communication across the plurality of local networks to the access networks 4a and 4b.

  Furthermore, in the second embodiment, when the edge switches 80a and 80b receive a frame from the access network, the received frame communicates across a plurality of access networks based on the stored wide area definition information. It is determined whether or not it is from the VLAN to be performed. The edge switches 80a and 80b transfer only the frames transmitted from the VLAN that performs communication across a plurality of local networks to the backbone network 5. In other words, the edge switches 80a and 80b do not transfer a frame from a VLAN that performs communication closed to one access network to the backbone network 5.

  Therefore, in the second embodiment, when there are a plurality of VLANs that perform closed communication in one access network, it is possible to assign the same VLAN-D (S-VID) to each VLAN. is there. Therefore, according to the second embodiment, the number of VLANs exceeding the upper limit number of VLAN IDs that can be set by Ethernet (registered trademark) can be set. Therefore, the power communication network system according to the second embodiment can set more VLANs than the power communication network system described in the first embodiment.

  In addition, regarding VLANs that perform communication via the backbone network 5, communication can be performed between VLANs to which different VLAN IDs are assigned. Further, similarly to the first embodiment, since it can be constructed using only a layer 2 switch capable of communication by Ethernet (registered trademark), it is possible to reduce the cost for constructing the network.

  Next, the configuration of the edge switches 70a, 70b, 80a, and 80b according to the second embodiment will be described. Here, the edge switches 70a and 70b connected to the access network 4a basically have the same configuration as the edge switches 20a to 20c described in the first embodiment. That is, the edge switches 20a to 20c in the first embodiment are connected to the wide area network 2, but the edge switches 70a and 70b in the second embodiment are only connected to the access networks 4a and 4b. . Therefore, the description of the configuration of the edge switches 70a and 70b is omitted here.

  Hereinafter, the configuration of the edge switches 80a and 80b according to the second embodiment will be described. Since both edge switches 80a and 80b have the same configuration, the edge switch 80a will be described as an example here. In the following, a frame transferred by the access networks 4a and 4b is called an “access network frame”, and a frame transferred by the backbone network 5 is called a “backbone network frame”.

  FIG. 10 is a functional block diagram illustrating the configuration of the edge switch 80a connected to the backbone network 5 according to the second embodiment. As shown in FIG. 10, the edge switch 80a includes an access network MAC address table 81a, a backbone network MAC address table 81b, a VID conversion table 82, an access network frame transmission / reception unit 83, a backbone network frame transmission / reception unit 84, A frame processing unit 85.

  Here, before describing each part of the edge switch 80a, the formats of the access network frame and the backbone network frame will be described.

  The format of the access network frame is the same as the format of the wide area network frame shown in FIG. Therefore, the description is omitted here.

  FIG. 11 is a diagram illustrating an example of a format of a backbone network frame according to the second embodiment. As shown in FIG. 11, the backbone network frame includes, for example, “wide area destination address”, “wide area source address”, “third tag information”, “fourth tag” as areas in which various values are set. "Information", "destination address", "source address", "second tag information", "first tag information", "length / type", "user data", and "FCS (Frame Check Sequence)" Have

  The wide area destination address is an area in which the MAC address of the edge switch that is the transfer destination of the backbone network frame is set. The wide area transmission source address is an area in which the MAC address of the edge switch that becomes the transfer source of the backbone network frame is set. Here, the wide area destination address and the wide area source address have the same format as the destination address and the source address of the private network frame shown in FIG. 4, respectively. Therefore, the backbone network frame can be transferred by Ethernet (registered trademark) in the same manner as the local network frame shown in FIG.

  The third tag information and the fourth tag information are areas in which various information for performing various processes related to the VLAN in the backbone network is set. Here, the information set in the third tag information includes B-VID which is an identifier for identifying the backbone network frame. This B-VID has the same format as the C-VID of the local network frame shown in FIG. 4 and the S-VID of the wide-area frame shown in FIG. The information set in the fourth tag information includes an I-SID for identifying the VLAN in the backbone network.

  The area from the destination address to the user data is the same as the area of the same name included in the access network frame in the second embodiment. FCS is an area in which a CRC value for detecting an error in a backbone network frame is set.

  In this way, the backbone network frame encapsulates the access network frame with “wide area destination address”, “wide area source address”, “third tag information”, and “fourth tag information” as headers. is there.

  Returning to the description of FIG. 10, the access network MAC address table 81a is an output to which the MAC address of the terminal device connected to the edge switch 80a via the access network 4a and the edge switch having the MAC address are connected. It is the table which matched the port. The access network MAC address table 81a is updated by an access network MAC address table update unit (not shown). Specifically, the access network MAC address table update unit uses the transmission address of the access network frame received from the access network 4a and the transmission source address of the access network frame received from the frame processing unit 85 to use the access network MAC. The address table 81a is updated.

  The backbone network MAC address table 81b associates the MAC address of another edge switch connected to the edge switch 80a via the backbone network 5 with the output port to which the edge switch having the MAC address is connected. It is a table. The backbone network MAC address table 81b is updated by a backbone network MAC address table update unit (not shown). Specifically, the backbone network MAC address table update unit updates the backbone network MAC address table 81 b using the wide area transmission address of the backbone network frame received from the backbone network 5.

  By the way, normally, in the layer 2 switch, there is an upper limit to the number of MAC addresses that can be set in the MAC address table from the mounted memory and processing performance. Conventionally, the upper limit of the MAC address table sometimes hinders the expansion of the network scale. However, if the MAC address of the edge switch is set in the wide area destination address and the wide area source address of the backbone network frame as in the second embodiment, the backbone network frame is transferred without using the MAC address of the terminal device. Will be able to. Therefore, it is possible to reduce the number of MAC addresses set in the MAC address table, and it is possible to cope with an increase in the scale of the power communication network system.

  The VID conversion table 82 stores wide area definition information indicating whether or not the VLAN via the access network accommodated by the edge switch 80a communicates across a plurality of access networks. Specifically, as illustrated in FIG. 9, the VID conversion table 82 stores, for each VLAN, information in which I-SID and S-VID are associated with each other as wide-area definition information.

  The access network frame transmission / reception unit 83 controls transmission / reception of access network frames exchanged with the access network 4a. Specifically, when the access network frame transmission / reception unit 83 receives an access network frame from the access network 4 a, the access network frame transmission / reception unit 83 transfers the received access network frame to the frame processing unit 85. Further, when the access network frame is transferred from the frame processing unit 85, the access network frame transmission / reception unit 83 refers to the access network MAC address table 81a and outputs corresponding to the destination address of the transferred access network frame. Identify the port. Then, the access network frame transmission / reception unit 83 transmits the access network frame to the access network 4a via the specified output port.

  The backbone network frame transmission / reception unit 84 controls transmission / reception of backbone network frames exchanged with the backbone network 5. Specifically, when the backbone network frame transmission / reception unit 84 receives a backbone network frame from the backbone network 5, the backbone network frame transmission / reception unit 84 transfers the received backbone network frame to the frame processing unit 85. Further, when the backbone network frame is transferred from the frame processing unit 85, the backbone network frame transmission / reception unit 84 refers to the backbone network MAC address table 81b and outputs corresponding to the destination address of the transferred backbone network frame. Identify the port. Then, the frame processing unit 85 transmits the backbone network frame to the backbone network 5 through the specified output port.

  The frame processing unit 85 generates an access network frame and a backbone network frame based on definition information registered in the VID conversion table 82. Specifically, the frame processing unit 85 generates a backbone network frame by encapsulating the access network frame transferred from the access network frame transmission / reception unit 83 based on the definition information registered in the VID conversion table 82. To do. The frame processing unit 85 extracts an access network frame from the backbone network frame transferred from the backbone network frame transmission / reception unit 84. The processing performed by the frame processing unit 85 will be described in detail in the frame transfer flow described below.

  Next, a flow of frame transfer performed by the edge switch 80a connected to the backbone network 5 according to the second embodiment will be described. FIG. 12 is a flowchart illustrating the flow of frame transfer performed by the edge switch 80a connected to the backbone network 5 according to the second embodiment.

  As shown in FIG. 12, in the edge switch 80a, when the access network frame transmission / reception unit 83 receives an access network frame (Yes in step S201), the frame processing unit 85 refers to the VID conversion table 82 (step S201). S202), it is confirmed whether or not an I-SID corresponding to the S-VID of the received access network frame is defined (step S203).

  Here, when the I-SID is defined (step S204, Yes), the frame processing unit 85 converts the access network frame using the I-SID corresponding to the S-VID of the received access network frame. By encapsulating, a backbone network frame is generated (step S205). Then, the frame processing unit 85 transfers the generated backbone network frame to the backbone network 5 via the backbone network frame transmission / reception unit 84 (step S206).

  If the I-SID corresponding to the S-VID of the received access network frame is not defined (step S204, No), the frame processing unit 85 discards the received access network frame (step S207). ).

  On the other hand, when the backbone network frame transmission / reception unit 84 receives the backbone network frame (step S208, Yes), the frame processing unit 85 refers to the VID conversion table 82 (step S209), and S of the received access network frame. -It is confirmed whether or not the I-SID corresponding to the VID is defined (step S210).

  Here, when the I-SID is defined (step S211, Yes), the frame processing unit 85 extracts an access network frame from the received backbone network frame (step S212). Then, the frame processing unit 85 transfers the extracted access network frame to the access network 4a via the access network frame transmission / reception unit 83 (step S213).

  If the S-VID corresponding to the C-VID of the received backbone network frame is not defined (No at Step S211,), the frame processing unit 85 discards the received backbone network frame (Step S214). ).

  As described above, in the second embodiment, the edge switches 70a to 70d, the edge switches 80a and 80b, and the relay switch 90 are layer 2 switches that can communicate by Ethernet (registered trademark).

  Therefore, according to the second embodiment, in the power communication network system, it is possible to reduce the cost for constructing the network.

  In the second embodiment, the power communication network system is a backbone network 5 that accommodates a plurality of access networks 4a and 4b, and an edge that relays communication performed between the access networks 4a and 4b and the backbone network 5. Switches 80a and 80b. Then, in the edge switches 80a and 80b, the VID conversion table 82 indicates the wide area definition information indicating whether or not the VLAN via the access network accommodated by the own device communicates across a plurality of access networks. Remember. Further, the access network frame transmission / reception unit 83 receives a frame from the access network accommodated by the own device. When a frame is received by the access network frame transmission / reception unit 83, the frame processing unit 85 uses the wide-area definition information stored in the VID conversion table 82 to cause the received frame to straddle a plurality of access networks. Then, it is determined whether or not the transmission is from a VLAN that performs communication. Furthermore, the frame processing unit 85 transfers only the frame determined to be transmitted from the VLAN that performs communication across a plurality of access networks to the backbone network 5 via the backbone network frame transmission / reception unit 84.

  Therefore, according to the second embodiment, when there are a plurality of VLANs that perform closed communication in one access network, it is possible to assign the same VLAN-D (S-VID) to each VLAN. is there. Therefore, according to the second embodiment, the number of VLANs exceeding the upper limit number of VLAN IDs that can be set by Ethernet (registered trademark) can be set. Therefore, the power communication network system according to the second embodiment can set more VLANs than the power communication network system described in the first embodiment. In addition, regarding VLANs that perform communication via the backbone network 5, communication can be performed between VLANs to which different VLAN IDs are assigned.

  In the second embodiment, the VID conversion table 82 uses the S-VID for identifying the VLAN in the access network 4 a and the VLAN in the backbone network 5 for the VLAN that communicates across a plurality of access networks. Information associated with the third identification information to be identified is stored as wide area definition information. When the frame processing unit 85 associates the I-SID with the S-VID set in the frame received by the access network frame transmission / reception unit 83, the frame extends over a plurality of access networks. It is determined that the transmission is from a VLAN that performs communication.

  Therefore, according to the second embodiment, the frame transfer in the backbone network 5 can be controlled only by storing the information in which the S-VID and the I-SID are associated with each other in the edge switches 80a and 80b. A network can be easily constructed.

  In the second embodiment, a case has been described in which “facility maintenance data collection VLAN” and “main protection VLAN” are used as VLANs set in the local network. However, the present invention is not limited to this, and can be similarly applied even when a VLAN for another application is used.

  In the second embodiment, the case where a terminal device, a data terminal, and a server are used as devices connected to the local area network has been described. However, the present invention is not limited to this, and can be similarly applied even when other types of communication devices are used.

  As described above, the communication network system and the communication control method according to the present invention are useful when a communication network is constructed using IP technology, and particularly when it is required to reduce the cost for constructing the network. Suitable for

1a to 1d, 3a to 3d Local network 2 Wide area network 4a and 4b Access network 5 Backbone network 10a to 10g, 60a to 60d Terminal device 20a to 20c Edge switch 21 MAC address table 22, 82 VID conversion table 23 Local network frame transmission / reception unit 24 Wide area network frame transmission / reception unit 25, 85 Frame processing unit 30, 90 Relay switch 40a, 40b Server 50a, 50b Data terminal 70a-70d, 80a, 80b Edge switch 81a Access network MAC address table 81b Backbone network MAC address table 83 Access network Frame transceiver unit 84 Backbone network frame transceiver unit

Claims (6)

A communication network system having a plurality of local networks, a wide area network that accommodates each local area network, and a relay device that relays communication performed between the local area network and the wide area network,
The communication network system, wherein the relay device is a layer 2 switch. The relay device is
Definition information storage means for storing definition information indicating whether or not a virtual network set in a local network accommodated by the own device communicates across a plurality of local networks;
Frame receiving means for receiving a frame from a local network accommodated by the device;
When a frame is received by the frame receiving means, the frame is transmitted from a virtual network that communicates across a plurality of local networks based on the definition information stored in the definition information storage means. Transfer determination means for determining whether there is,
And a frame transfer unit that transfers only frames determined to be transmitted from a virtual network that communicates across a plurality of local networks to the wide area network. Item 4. The communication network system according to Item 1. The definition information storage means identifies first identification information for identifying the virtual network in the local network and the virtual network in the wide area network for a virtual network that communicates across a plurality of local networks. Storing the information associated with the second identification information as the definition information;
The forwarding determination means, when the second identification information is associated with the first identification information set in the frame received by the frame receiving means, the frame spans a plurality of local networks. The communication network system according to claim 2, wherein the communication network system is determined to be transmitted from a virtual network that performs communication. A backbone network that accommodates a plurality of wide area networks, and a wide area relay device that relays communications performed between the wide area network and the backbone network,
The wide area relay device is a layer 2 switch,
Wide-area definition information storage means for storing wide-area definition information indicating whether or not a virtual network via a wide-area network accommodated by the own device communicates across a plurality of wide-area networks;
A wide area network frame receiving means for receiving a frame from the wide area network accommodated by the device;
When a frame is received by the wide area network frame receiving means, the frame is transmitted from a virtual network that communicates across a plurality of wide area networks based on the wide area definition information stored in the wide area definition information storage means. Wide-area transfer determination means for determining whether or not
A wide area network frame transfer means for transferring only a frame determined to be transmitted from a virtual network that communicates across a plurality of wide area networks by the wide area transfer determination means to the backbone network. The communication network system according to claim 1, 2, or 3. The wide area definition information storage means, for a virtual network that communicates across a plurality of wide area networks, the second identification information for identifying the virtual network in the wide area network, and the virtual network in the backbone network Information associated with third identification information to be identified is stored as the wide area definition information;
When the third identification information is associated with the second identification information set in the frame received by the wide area network frame reception unit, the wide area transfer determination unit The communication network system according to claim 4, wherein the communication network system is determined to be transmitted from a virtual network that performs communication across a network. A communication control method applied to a communication network system having a plurality of local networks, a wide area network that accommodates each local area network, and a relay device that relays communication performed between the local area network and the wide area network. And
The relay device is a layer 2 switch,
The relay device receives a frame from a local network accommodated by the device;
Definition information indicating whether or not a virtual network set in the local network accommodated by the relay apparatus communicates across a plurality of local networks when the relay apparatus receives a frame Determining whether the frame is transmitted from a virtual network that communicates across a plurality of local networks, with reference to the storage unit in which
The relay apparatus includes a step of transferring only frames determined to be transmitted from a virtual network that performs communication across a plurality of local networks to the wide area network. .

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