WO2006027817A1

WO2006027817A1 - Communication system and node apparatus

Info

Publication number: WO2006027817A1
Application number: PCT/JP2004/012829
Authority: WO
Inventors: Shoichiro Seno; Teruko Fujii; Tetsuya Yokotani
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 2004-09-03
Filing date: 2004-09-03
Publication date: 2006-03-16
Also published as: JPWO2006027817A1; JP4437818B2

Abstract

Each of node apparatuses (21-25) compares a VLAN identifier set in a VLAN tag within a Layer 2 frame received from a trunk link (1) with a predetermined VLAN identifier, which is VLAN information associated with a branch network (31-35) accommodated by the node apparatus, to determine whether the received Layer 2 frame is addressed to the branch network (31-35) accommodated by the node apparatus. If so, the node apparatus (21-25) transmits the Layer 2 frame from which the VLAN tag has been removed to the branch network (31-35) accommodated by the node apparatus, and otherwise, transmits the Layer 2 frame to a trunk link (1) located in a different direction than the trunk link (1) from which the Layer 2 frame was received.

Description

Specification

Communication system and node device

Technical field

TECHNICAL FIELD [0001] The present invention relates to a communication system that performs communication using a layer 2 frame, and particularly to a communication system in which node devices are arranged so as to connect trunk links in a loop shape.

Background art

Conventionally, in order to improve the reliability of a communication system, various techniques when a failure occurs in a transmission line have been considered. For example, in a communication system that consists of multiple Layer 2 switches (hereinafter referred to as L2 switches) that switch Ethernet (registered trademark) frames (hereinafter referred to as L2 frames), L2 switches associate destination MAC addresses with circuit ports. A table called forwarding database is stored, the destination MAC address of the frame header in the L2 frame is compared with the destination MAC address of the forwarding database, the L2 frame forwarding destination line port is selected, and the L2 frame is forwarded To do. Then, by using the spanning tree protocol between the L2 switches, the logical topology between the L2 switches, which is the L2 frame transfer path, is uniquely determined.When a failure is detected, the logical topology is changed and the forwarding database is reconfigured. Bypassing obstacles (see Non-Patent Document 1, for example).

[0003] However, with the conventional technology described in Non-Patent Document 1 that reconfigures the forwarding database using the spanning tree protocol when a failure is detected, it takes time to change the forwarding database. There was a problem that it was not suitable for bypassing failures in L2 frames equipped with data requiring real-time performance.

[0004] In order to improve such a problem, Patent Document 1 discloses a network in which two transmission paths, a working path and a backup path, are set in advance and can be quickly switched to a backup path when a failure of the working path is detected. A transfer system technique is disclosed. Specifically, a VLAN (Virtual Local Area Network) for frame transfer for the working path and a VLAN for frame transfer for the backup path are set in advance as a VLAN table between the L2 switches. Keep it. During frame transfer, each L2 switch compares the VLAN tag contained in the L2 frame with the set VLAN table and selects the transfer destination line port. Forward through the VLAN.

[0005] Further, Patent Document 2 discloses a technique for quickly switching to a backup path when a failure of the working path is detected when the communication system forms a ring (loop) network. Specifically, MPLS (Multi Protocol Label Switching) technology is used between the node device that inputs a frame to the ring network and the node device that outputs the frame. When a frame is transferred, the MPLS label in the frame is compared with the set label table to select the transfer destination line port, and when a failure in the working path is detected, the frame is prepared. Transfer to the route.

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2003-158539

Patent Document 2: Japanese Patent Laid-Open No. 2003-224586

Non-Patent Document 1: Rich Seifert "LAN switching thorough explanation" Nikkei BP Publishing 20 August 6, 2001

Disclosure of the invention

Problems to be solved by the invention

[0007] However, in the above three conventional technologies, each L2 switch or node device uses the L2 frame header information and the forwarding database, or the set VLAN or MPLS label table during frame transfer. In comparison, the line port to which the L2 frame is forwarded is selected, so that each L2 switch or node device consumes memory for storing the forwarding database, or the table of VLAN or MPLS label. There was a problem that the comparison of the table and the header information of the frame caused a load on the L2 frame transfer processing.

[0008] In addition, in the prior arts of Patent Document 1 and Patent Document 2 described above, a technique for logically defining an L2 frame transfer destination, such as a VLAN technique or an MPLS technique, is used in order to reduce the time required for fault bypassing. Since the route and the backup route are set in advance, for each pair of the current route and the backup route, each end point of the current route and the backup route is set. In addition, it is necessary to set a VLAN or MPLS label table on all L2 switches or node devices installed in the middle, which causes problems when network settings become complicated.

[0009] The present invention has been made in view of the above, and reduces the amount of information set in a node device in a communication system to suppress memory consumption, and transfers at the time of transferring a layer 2 frame The first object is to obtain a communication system and a node device that reduce the processing load for selecting a previous port.

[0010] A second object of the present invention is to set information on a plurality of pairs of a current path and a backup path using a single control frame when the current path and the backup path are set in advance. It is to obtain a communication system and a node device that are set only for the node devices at the respective end points of and.

Means for solving the problem

In order to solve the above-described problems and achieve the object, the present invention provides a plurality of node devices having two trunk ports that accommodate trunk links and one or more branch ports that accommodate branch networks. Connected in a loop shape via the trunk link, and communicates by transmitting the layer 2 frame received from the branch network accommodated in its own device via the trunk link to the branch network accommodated in the node device as the communication partner In the communication system, the node device has a first VLAN identifier indicating a forward path of a loop-shaped trunk link connecting the branch network accommodated by the own device and the branch network accommodated by the counterpart node device. And a VLAN setting table in which a second VLAN identifier indicating a route in the direction opposite to the forward direction is set, and a branch network that the device itself accommodates When receiving a layer 2 frame from the branch port, and a control unit that selects the power of transmitting the layer 2 frame received from the forward path using the forward path and the force of transferring using the reverse path Includes a tagged layer 2 frame obtained by adding a VLAN tag including a first or second LVAN identifier indicating the route selected by the control unit to the layer 2 frame, and a trunk link of the selected route. When a tagged layer 2 frame is received from the trunk port that is transmitted through the accommodated trunk port, the first and second VLAN identifiers set in the VLAN setting table and the tagged layer 2 frame VL Based on the VLAN identifier set in the AN tag, it is determined whether the tagged layer 2 frame received is addressed to the branch network accommodated by the local device, and the received tagged layer 2 frame is the local device. If it is destined for the branch line network accommodated by the network, the received layer 2 frame with the tagged tag is sent to the branch network via the branch line port, and the received layer 2 frame with the tag is received. A relay unit that transmits the tagged layer 2 frame to the trunk link via a trunk port that is different from the trunk port that received the tagged layer 2 frame. .

The invention's effect

[0012] The communication system according to the present invention accommodates the branch network and the counterpart node device accommodated in the own device set in the VLAN setting table of the relay unit force of the node device connected in a loop shape via the trunk link. The first and second VLAN identifiers indicating the route of the loop-shaped trunk link that connects to the branch network to be connected and the V tag set in the VLAN tag of the Layer 2 frame with VLAN tag received from the trunk port that accommodates the trunk link Since it is judged whether the tagged layer 2 frame received based on the LAN identifier is addressed to the branch network accommodated by the own device, the tagged layer 2 frame is accommodated by the own device. Whether or not it is destined for the branch network ^ The amount of information to be judged can be reduced, memory consumption is reduced, and tagged layer 2 frames are An effect that it is possible to reduce the processing load of selecting a transfer destination of the ports in forwarding. Brief Description of Drawings

FIG. 1 is a diagram showing an example of a configuration of a communication system according to the present invention.

FIG. 2 is a block diagram showing a configuration of the node device shown in FIG.

[FIG. 3] FIG. 3 is a diagram showing a configuration of a layer 2 frame used in a branch network of a communication system according to the present invention.

[FIG. 4] FIG. 4 is a diagram showing a structure of a layer 2 frame used in a trunk link of a communication system according to the present invention.

[FIG. 5] FIG. 5 is a diagram showing the configuration of a control frame for VLAN setting used to set information on a forward path and a reverse path in a node device of a communication system according to the present invention. FIG.

[Fig. 6] Fig. 6 is a diagram showing a failure location of the trunk link of the communication system shown in Fig. 1.

FIG. 7 is a flowchart for explaining the operation of the node device that is the starting point of the loop.

FIG. 8 is a flowchart for explaining the operation of a node device other than the node device that is the starting point of the loop.

FIG. 9 is a flowchart for explaining an operation in which a node device transmits an L2 frame received from a branch network accommodated by the node device to a trunk link.

FIG. 10 is a flowchart for explaining an operation in which the node device transmits an L2 frame received from the trunk link.

Explanation of symbols

[0014] 1 Main link

21, 22, 23, 24, 25 Node equipment

31, 32, 33, 34, 35 Branch network

41, 42 VLAN

101, 10η branch port

111, 112 trunk port

120 Relay section

130 Control unit

140 VLAN setting table

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of a communication system and a node device according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

With reference to FIG. 1 and FIG. 10, an embodiment of the present invention will be described. FIG. 1 is a diagram showing an example of a configuration of a communication system according to the present embodiment that is useful for the present invention. The communication system of the present embodiment according to the present invention switches the trunk link 1 constituting the loop-shaped network and the Ethernet (registered trademark) frame (hereinafter referred to as L2 frame). Multiple node devices 21-25 (5 in this case) that have the function of layer 2 switch (hereinafter referred to as L2 switch) and branch network 31- of loop-shaped network accommodated in node device 21-25 35, a virtual local area network (VLAN) 41 used between the node equipment 21 and the node equipment 23 and used as a forward path for communication between the branch network 31 and the branch network 33, and a branch line For communication between the network 31 and the branch network 33, a VLAN 42 set between the node device 21 and the node device 23 and used as a reverse path is provided.

[0017] The forward direction and the reverse direction are references indicating the directions in which the node devices 21-25 transfer L2 frames in a loop-shaped network, and are assumed to be predetermined. For example, with one node device 21 as the base point, all node devices 21 25 are given node numbers that increase in value when the loop-shaped network is circulated in one direction, and the node numbers increase in the ascending order. Transfer is defined as forward, and transfer in descending order is defined as reverse. In the following, the L2 frame transfer on the trunk link 1 will be described assuming that the forward direction and the reverse direction are constantly determined.

The node devices 21-25 all have the same function. The function of the node device will be described with reference to the block diagram showing the configuration of the node device 21 shown in FIG. The node device 21 includes n (n is a natural number) branch port ports 101-10η that accommodate the branch network 31 and trunk port ports 111 and 112 that accommodate the trunk link 1 between the adjacent node devices 22 and 25. VLAN configuration table 140 that stores VLAN information in the forward and reverse VLANs of the branch network 31 and the pair of branch networks 32—35 accommodated by its own device, and the L2 switch function and the branch spring port 101— 1 Set the VLAN information in the VLAN setting table 140 and the relay unit 120 that forwards L2 frames between the On and trunk port 111, 112 and between the trunk f spring port 111 and the trunk f spring port 112 Controls the operation of the local device, such as determining the working route and the backup route with one of the forward route and the reverse route as the working route and the other as the backup route, and switching between the working route and the backup route when a failure is detected. And a control unit 130.

[0019] The L2 frame handled by the communication system of the present embodiment, which is useful for the present invention, will be described with reference to FIGS. FIG. 3 is a diagram showing a configuration of the L2 frame 200 used for data transfer between the node devices 21-25 and the branch network 31-35. The L2 frame 200 is It consists of a frame header 201 and data 202.

[0020] The frame header 201 is a general MAC header defined in Ethernet (registered trademark) and the IEEE 802.3 standard, and header information such as the destination MAC address and the source MAC address of the L2 frame 200 is set. Is done. In data 202, data to be transmitted is set.

[0021] FIG. 4 shows an L2 frame used for data transfer on the trunk link 1 by the node equipment 21-25.

It is a figure which shows the structure of 210 (the layer 2 frame with a tag as said in a claim). In the L2 frame 210, a VLAN tag 203 including a VLAN identifier indicating a forward path or a reverse path is added between the frame header 201 and the data 202 of the L2 frame 200 shown in FIG. Yes.

FIG. 5 is a diagram showing a configuration of a VLAN setting control frame 300 used for setting information related to the forward route and the backward route in the node devices 21-25. The VLAN setting control frame 300 includes a frame header 301, control information 302, and VLAN information 303.

[0023] The frame header 301 is a general MAC header defined in Ethernet (registered trademark) and the IEEE 802.3 standard, and header information such as a destination MAC address and a source MAC address is set therein. For the destination MAC address, a specific value indicating that the VLAN setting control frame 300 is addressed to all the node devices 21-25 on the loop-shaped network is used. In the control information 302, control information including information for identifying the VLAN setting control frame 300 is set. When a failure is detected, a turn-back flag indicating that a failure has occurred is set.

[0024] The VLAN information 303 includes m (m is a natural number) pieces of VLAN identifiers of a forward path and a reverse path corresponding to a branch network 31 35 pair and a pair of branch network 31 35 pairs. Consists of field 310.

The field 310 includes a route type 311, branch network information 312 and 313, and VLAN identifiers 314 and 315. In the route type 311, a route type is set that includes a set of a route in the reverse direction and a route in the forward direction.

[0026] The branch network information 312 and 313 include a pair of branch lines to be communicated via the trunk link 1. Information to identify network 31-35 is set. Specifically, for example, a set of a combination of a node number assigned to the node device 21-25 and a port number of the branch port 1101-10η accommodated by the node device 21-25 is set.

[0027] In the 1 ^ 1 ^ identifiers 314 and 315, the VLAN of the forward route used for transferring the L2 frame 200 to and from the branch network 31 35 set in the branch network information 312 and 313 is identified. The VLAN identifier for identifying the VLAN in the reverse direction and the VLAN identifier for identifying the VLAN in the reverse direction are set. For example, the VLAN identifier 314 is set with the VLAN identifier of the forward route, and the VLAN identifier 315 is set with the VLAN identifier of the reverse route.

[0028] Next, the operation of the communication system of the present embodiment according to the present invention will be described. First, the operation of setting information on the forward route and the reverse route in the node devices 21-25 in the communication system will be described. Information on the forward and reverse routes to node equipment 21 25 is set by adding a pair of branch networks 31-35 that transfer L2 frame 200 during initial setup of the communication system or during operation of the communication system. Executed when deleting or deleting. Note that the VLAN identifier indicating the forward route and the VLAN identifier indicating the reverse route are set on the loop-shaped network for each branch network 31-35 that transfers the L2 frame 200 when the communication system is initialized. Is selected to be unique.

[0029] If the node device 21 is a node device that is a starting point of a loop when setting information on a forward route and a reverse route, the node device 21 generates a VLAN setting control frame 300. The VLAN setting control frame 300 is transmitted to the trunk link 1 using the forward or reverse route.

[0030] If the node device 21 transmits the VLAN setting control frame 300 using the reverse path, the VLAN setting control frame 300 is transmitted from the node device 25, the node device 24, the node device 23, and the node device 22 to each other. The node device 21 is reached in order.

[0031] Here, the node device 21 generates a VLAN configuration control frame 300 for setting the VLAN information of the pair of the branch network 31 and the branch network 33 that sets the VLAN 41 as the forward direction and the VLAN 42 as the reverse direction. Suppose that VLAN configuration control frame 300 Information for identifying the branch line network 31 is set in the branch line network information 312 of the field 310, and information for identifying the branch line network 33 is set in the branch line network information 313.

[0032] Since the information set in the branch network information 312, 313 is different from the branch networks 35, 34 that the own device accommodates in the node devices 25, 24, the VLAN setting control is not performed. The frame 300 is transferred to the next node devices 24 and 23.

[0033] Since the information set in the branch network information 313 indicates the branch network 33 accommodated by the node device 23, the node device 23 sets VLAN information based on the field 310, and controls VLAN setting The frame 300 is transferred to the next node device 22.

[0034] Since the node device 22 is different from the branch network 32 accommodated in the information power own device set in the branch network information 312 and 313, the node device 22 does not set the VLAN configuration control frame 300 next. To the node device 21 of the node. By receiving the VLAN setting control frame 300 from the node device 22, the node device 21 recognizes that the VLAN setting has been normally completed.

Here, as shown in FIG. 6, it is assumed that a failure 99 occurs between the node device 22 and the node device 21. Even if node device 22 receives VLAN configuration control frame 300, failure 99 has occurred in forwarding trunk link 1, and therefore VLAN configuration control frame 300 cannot be forwarded to node device 21. .

When the failure 99 is detected, the node device 22 uses the flag indicating the occurrence of loopback in the control information 302 of the VLAN setting control frame 300 to notify the node device 21 that the failure 99 has occurred. Is transmitted to the node device 23 on the other side that has received the control frame 300 for VLAN setting.

[0037] The node device 23-25 that has received the VLAN setting control frame 300 in which the return flag is set forwards the VLAN setting control frame 300 to the node devices 24, 25, and 21 opposite to the receiving side. To do.

The node device 21 recognizes the failure 99 because the return flag is set in the control information 302 of the received VLAN setting control frame 300. In this case, node device 2 A failure 99 has occurred between node device 22 and node device 21 after VLAN information is set in 3. For example, if a failure has occurred between node device 24 and node device 23 In this case, the node device 24 sets the return flag in the control information 302 and transfers the control frame 300 for VLAN setting. In this case, VLAN information is not set in the node device 23. Therefore, the node device 21 transmits the VLAN setting control frame 300 again in the forward direction. As a result, it is possible to set information regarding the forward path and the reverse path to all node devices existing outside the failure detection range.

With reference to the flowchart of FIG. 7, the operation of the node device that is the starting point of the loop will be described in detail. Note that the VLAN identifier indicating the forward path and the VLAN identifier indicating the reverse path are loop-shaped for each pair of all branch network 31 35 that transfers the L2 frame 200 when the communication system is initialized. It shall be selected to be unique on the network.

The control unit 130 generates a VLAN setting control frame 300 (see FIG. 5) (step S 100). Specifically, the control unit 130 sets a route type in which the field 310 includes a pair of a forward route and a reverse route in the route type 311. The control unit 130 of the node device 21 sets information for identifying the VLAN setting control frame 300 in the control information 302.

[0041] When the branch network pair communicating via the trunk link 1 is the branch network 31 and the branch network 33, the control unit 130 is a node as information for identifying the branch network 3 1 in the branch network information 312. A combination of the node number assigned to the device 21 and the port number of the branch port 101-10η of the node device 21 is set, and the node number assigned to the node device 23 as information for identifying the branch network 33 in the branch network information 313 is set. Set the combination of the node number and branch port 101 of node equipment 23—the port number of 10η, set the VLAN identifier of VLAN 41 of the forward route to V LAN identifier 314, and the reverse route to VLAN identifier 315. Set the VLAN identifier of VLAN 42 to create field 310. Similarly, the control unit 130 generates a field 310 corresponding to a pair of communicable branch networks, and adds the VLAN information 303 having the generated field 310 power after the control information 302 to control VLAN setting control frames. Generate 300.

The control unit 130 transmits the generated VLAN setting control frame 300 to the trunk unit 120 with the relay unit 120. To the main link 1 of the forward route or the reverse route via the first port 111 or the main port 112 (step S110).

When the VLAN setting control frame 300 is received via the trunk ports 111 and 112 (step S 120), the relay unit 120 outputs the VLAN setting control frame 300 to the control unit 130. The control unit 130 determines whether or not a return flag is set in the control information 302 of the received VLAN setting control frame 300 (step S130). If the return flag is not set, it is recognized that the VLAN information has been set, and the process ends.

[0044] When the return flag is set, the control unit 130 outputs the VLAN setting control frame 300 to the relay unit 120, and the relay unit 120 transmits a trunk in a direction different from the direction in which the transmission is first performed. The VLAN setting control frame 300 is transmitted again via the line ports 111 and 112 (step S140). For example, when the VLAN setting control frame 300 is first transmitted from the trunk port 111, the VLAN setting control frame 300 is transmitted via the trunk port 112, and the VLAN setting control frame 300 is transmitted first from the trunk port 112. In this case, the VLAN setting control frame 300 is transmitted to the trunk link 1 via the trunk port 111.

Next, the operation of the node device other than the node device that is the starting point of the loop will be described in detail with reference to the flowchart of FIG. When the VLAN setting control frame 300 is received via the trunk ports 111 and 112 (step S200), the relay unit 120 outputs the VLAN setting control frame 300 to the control unit 130.

The control unit 130 determines whether or not the loopback flag is set in the control information 302 of the VLAN setting control frame 300 (step S201). When the loopback flag is set, the control unit 130 outputs the VLAN setting control frame 300 to the relay unit 120.

The relay unit 120 transmits the VLAN setting control frame 300 input from the control unit 130 via the trunk ports 112 and 111 different from the trunk ports 111 and 112 that have received the VLAN setting control frame 300 to the trunk link. 1 is transmitted (step S202). Specifically, when the VLAN setting control frame 300 is received from the trunk port 111, the VLAN setting control frame 300 in which the return flag is set to the trunk port 111 is transmitted to the trunk link 1 to set the VLAN. When the control frame 300 is received from the trunk port 112, the VLAN setting control frame 300 in which the return flag is set in the trunk port 112 is transmitted. Send to

[0048] When the loopback flag is not set, the control unit 130 examines the field 310 constituting the VLAN information 303 in order from the top and extracts information in order to extract the information in the top field 310 in the VLAN information 303. A pointer is set (step S203).

[0049] The control unit 130 determines whether or not it indicates the branch network 31-35 accommodated by the information processing apparatus itself set in the branch network information 312 and 31 3 of the field 310 where the pointer is located. (Step S204).

[0050] One of the information set in the branch network information 312 and 313 When the branch network 31 35 accommodated by the own device is indicated, the control unit 130 identifies the VLAN identifier in the field 310 where the pointer is located. 314, 315 acquires the VLAN identifier set in setting the forward VLAN and reverse VLAN to VLAN setting table 140 (step S205) _o example, the information set in the branch network information 312, the own When the branch line network 31-35 that the device can accommodate is indicated, the branch line network 31-35 indicated by the information set in the branch line network information 313 is paired with the branch line network 31-35 that the device itself accommodates. The VLAN identifier set in VLAN identifier 314 is set in VLAN configuration table 140 for the forward route so that it can be used as a route to the other branch network 31-35. , It sets the VLAN setting table 140 a VLAN identifier that is set to the VLAN identifier 315 for the reverse route.

[0051] After setting the forward and reverse routes in the VLAN setting table 140, the control unit 130 or the information power set in the branch network information 312 and 313 of the field 310 where the pointer is located When it is determined that the branch line network 31-35 to be accommodated is not indicated, it is determined whether or not the subsequent field 310 exists in the VLAN information 303 (step S206).

When it is determined that the subsequent field 310 exists in the VLAN information 303, the control unit 130 moves the pointer to the subsequent field 310, and the branch network information 312 and 313 of the field 3 10 to which the pointer is moved. Information power set in the own device It is determined whether or not it indicates the branch network 31 35 accommodated by the own device, and the information set in the branch network information 312 and 313 of the field 310 where the pointer is moved is accommodated in the own device. Do When the branch network 31-35 is indicated, the operation of setting the VLAN information in the VLAN setting tape node 140 is repeated until the subsequent field 310 disappears (steps S204-S207).

When the processing of the field 310 in the VLAN information 303 is completed, the control unit 130 outputs the VLAN setting control frame 300 to the relay unit 120. The relay unit 120 transmits the VLAN setting control frame 300 to the trunk link 1 via the trunk ports 111 and 112 different from the trunk ports 111 and 112 that have received the VLAN setting control frame 300 (step S208). That is, when the VLAN setting control frame 300 is received from the trunk port 111, the VLAN setting control frame 300 is transmitted to the trunk link 1 via the trunk port 112, and the VLAN setting control frame 300 is transmitted from the trunk port 112. If received, the VLAN setting control frame 300 is transmitted to the trunk link 1 via the trunk port 111.

If a failure is detected when transmitting the VLAN setting control frame 300, the relay unit 120 notifies the control unit 130 that the failure has been detected (step S209). The control unit 130 sets a return flag in the control information 302 of the VLAN setting control frame 300, and outputs the VLAN setting control frame 300 in which the return flag is set to the relay unit 120 (step S210). At that time, the control unit 130 notifies the relay unit 120 that the VLAN setting control frame 300 in which the return flag is set is transmitted via the trunk ports 111 and 112 that have received the VLAN setting control frame 300.

The relay unit 120 transmits the VLAN setting control frame 300 input from the control unit 130 via the trunk ports 111 and 112 notified from the control unit 130 to the trunk link 1 (step S211).

Next, the L2 frame transfer operation of the communication system will be described. The node device 21 25 stores the information on the forward route and the reverse route by the operation for setting the information on the forward route and the reverse route as described above. It shall be set to 140.

It is assumed that the node device 21 receives the L2 frame 200 (see FIG. 3) from the branch network 31 to the branch network 33. Node device 21 adds L2 frame with VLAN tag 203 including VLAN identifier indicating the transfer direction (forward or reverse) on trunk link 1 in L2 frame. Frame 210 (see Figure 4) is generated and sent to main link 1. Specifically, the node device 21 sets VLAN 41 to the VLAN tag 203 when transferring the L2 frame 210 in the forward direction, and sets the VLAN tag 203 to VLAN tag 203 when transferring the L2 frame 210 in the reverse direction. Set 42.

[0058] Since VLANs 41 and 42 are VLANs in which the branch network 31 and the branch network 33 are paired, they are set in the node device 23 and the node device 21, and are set in the node devices 22, 24, and 25. Not. Therefore, when the node device 21 forwards the L2 frame 210 in the forward direction, the node device 22 forwards the received L2 frame 210 to the next node device 23, and the node device 21 forwards the L2 frame 210 in the reverse direction. In this case, the node devices 25 and 24 transfer the received L2 frame 210 to the next node devices 24 and 23.

[0059] Since the node device 23 is set to the VLAN tag 203 of the L2 frame 210 received from the node device 22 or the node device 24, the VLAN identifier is the VLAN identifier set to the own device. The L2 frame 200 from which the VLAN tag 203 of the received L2 frame 210 is deleted is transmitted to the branch network 33.

[0060] Referring to the flowchart of FIG. 9, the node devices 21-25 generate branch network power accommodated by the own device. The received L2 frame 200 is generated by adding the VLAN tag 203 including the VLAN identifier to the received L2 frame 200. The operation of transmitting to the trunk link 1 will be described in detail. It should be noted that the relay unit 120 uses the branch network 31 accommodated by itself and the branch network 32-35 that is a communication partner via the trunk link 1 to send the destination MAC address of the device within the forwarding network (not shown) in the own device. Compare the destination MAC address contained in the frame header 201 of the L2 frame 200 received from the support network 31 with the learning content in the forwarding database, and select whether to transfer the L2 frame 200. Since the operation for determining the branch network 3 2-35 as the transfer destination when transferring the L2 frame 200 is the same as the function of a general L2 switch, a detailed description is omitted.

[0061] When the L2 frame 200 is received from the branch network 31-35 accommodated by the own device via the branch port 101 10η, the relay unit 120 refers to the forwarding database (FDB) and transfers the L2 frame 200 to the branch network. 31—35 is determined (Step S 300, S310). Specifically, in the case of the node device 21, the relay unit 120 of the node device 21 includes the destination MAC address and the forwarding database included in the frame header 201 of the L2 frame 200 received from the branch network 31 via the branch port 101-10η. Compare with. The relay unit 120 of the node device 21 determines a branch network 32 35 (transfer destination branch network) to which the L2 frame 200 is transferred based on the comparison result.

The relay unit 120 determines a VLAN corresponding to the forwarding branch network that transfers the L2 frame based on the notification from the control unit 130 (step S320). Specifically, the control unit 130 transfers the L2 frame 210 to the transfer branch network using the forward route VLAN based on the forward and reverse route states set in the control unit 130 in advance. Select whether to transfer the L2 frame 210 to the forwarding branch network using the VLAN of the reverse route, and notify the relay unit 120. For example, the control unit 130 selects a communicable route when only one of the forward and reverse directions is communicable, and when both the forward and reverse routes are communicable. For this, a route with a short transfer distance is selected and notified to the relay unit 120.

The relay unit 120 generates an L2 frame 210 in which a VLAN tag 203 including a VLAN identifier indicating the determined VLAN is added to the L2 frame 200 (step S330). The relay unit 120 transmits the L2 frame 210 to the trunk link 1 via the trunk ports 111 and 112 corresponding to the determined VLAN (step S340). For example, if the trunk port 111 accommodates the forward trunk link 1 and the trunk port 112 accommodates the reverse trunk link 1, the relay unit 120 selects the trunk port 111 if the determined VLAN is forward. The L2 frame 210 is transmitted via the trunk port 112 if the determined VLAN is in the reverse direction.

[0064] It should be noted that the forward route and the reverse route are intermediate routes such as VL AN41 and VLAN 42 that connect the branch network 31 and the branch network 33 of the communication system shown in FIG. Since the node equipment and the main link 1 are not shared, they can be used as a pair of a working route and a backup route without being simultaneously disabled due to a single failure. For example, when VLAN 41 is used as a working route and VLAN 42 is used as a backup route, even if a failure 99 occurs between the node device 21 and the node device 22 as shown in FIG. Then, the transfer of the L2 frame 210 between the branch network 31 and the branch network 33 is switched to the VLAN 41 via the VLAN 42 to realize communication bypassing the failure.

Next, the operation of the node apparatus when receiving the L2 frame 210 from the main link 1 will be described in detail with reference to the flowchart of FIG. When the relay unit 120 receives the trunk ports 111, 112, and the L2 frame 210, the relay unit 120 determines whether or not the VLAN tag 203 in the L2 frame 210 is addressed to the branch network 3135 accommodated by the own device ( Step S400, S410). Specifically, the relay unit 120 searches for a VLAN identifier indicating the VLAN information set in the VLAN setting table 140 using the VLAN identifier set in the VLAN tag 203 as a search key. As a result of the search, if there is a VLAN identifier that matches the VLAN identifier set in the VLAN tag 203 in the VLAN identifier set in the VLAN setting table, the relay unit 120 receives the received L2 frame 210 as its own device. It is determined that the address is addressed to the branch network 31 35 that accommodates. As a result of the search, if there is no VLAN identifier that matches the VLAN identifier set in the VLAN tag 203 in the VLAN identifier set in the VLAN setting table, the relay unit 120 has received it. The L2 frame 210 judges that it is not addressed to the branch network 31-35 accommodated by itself.

[0066] When the received L2 frame 210 is addressed to the branch network 31-35 accommodated by itself, the relay unit 120 deletes the VLAN tag 203 of the L2 frame 210 and generates the L2 frame 200 (step S420). .

The relay unit 120 transfers the L2 frame 200 via the destination branch network 31-35, that is, the branch port 101-10η of the branch network 31-35 accommodated by the own device (step S430).

When the received L2 frame 210 is not addressed to the branch network 31 35 accommodated by the own apparatus, the relay unit 120 passes through the trunk ports 111 and 112 different from the trunk ports 111 and 112 that have received the L2 frame 210. The L2 frame 210 is transferred to the main link 1 (step S44 0). Specifically, when the L2 frame 210 is received from the trunk port 111, the L2 frame 210 is transferred to the trunk link 1 via the trunk port 112, and when the L2 frame 210 is received from the trunk port 112. The L2 frame 210 is transferred to the trunk link 1 via the trunk port 111. As described above, in the present embodiment, the relay unit 120 of the node devices 21-25 has the VLAN identifier set in the VLAN tag 203 in the L2 frame 210 received from the trunk link 1 and the VLAN setting table. The branch network 31-35 accommodated by its own device is compared with the VLAN identifier which is the VLAN information associated with the branch network 31-35 accommodated by its own device set to 140. Therefore, the amount of information used to determine whether or not the L2 frame 210 is addressed to the branch network 31 1 to 35 accommodated by its own device is determined based on the conventional forwarding database or VLAN or The amount of information set in the MPLS label table can be reduced, the consumption of the VLAN setting table 140 is suppressed, and the forwarding destination port for forwarding the L2 frame 210 is selected. Processing load can be reduced.

In the present embodiment, the node device 21 that is the starting point of the loop generates the VLAN setting control frame 300, and uses the created VLAN setting control frame 300 using the forward or reverse route of the loop. The node devices 22-25, which are different from the node device 21 that is the starting point, receive the information set in the branch network information 312 and 313 of the control frame 300 for VLAN setting. Only the VLAN identifier in the field 310 indicating the branch network 31—35 is set in the VLAN setting table, and the VLAN setting control frame is sent via a trunk port different from the trunk port that received the VLAN setting control frame 300. Is sent to the trunk link 1, and the VLAN setting control frame 300 is circulated from the node device 21 that is the start point of the loop to the node devices 22-25. By using the VLAN setting control frame 300, which is a control frame, information on a plurality of pairs of working paths and backup paths can be set only in the node devices at the respective end points of the working path and backup paths.

In the present embodiment, a case has been described in which a forward path and a reverse path are set simultaneously. However, only a forward path or only a reverse path can be set. When only one route is set, the control unit 130 of the node device 21 that is the start point of the loop omits the VLAN identifier 315 and the VLAN identifier set in the VLAN identifier 314 indicates a forward route. The route type indicating whether the force indicates a reverse route is set to the route type 311, and the control unit 130 of the node device 22-25 It is only necessary to identify whether the route is a forward route or a reverse route from the route type 311 and store the VLAN identifier in the VLAN setting table 140.

[0072] Also, in the present embodiment, the control unit 130 uses the forward route VLAN to transfer the L2 frame 210 to the forwarding branch network, and uses the reverse route VLAN. The power to select whether to transfer the L2 frame 210 to the transfer branch network and to notify the relay unit 120 is not limited to this. For example, the control unit 130 adds the VLAN identifier of the forward route, the VLAN identifier of the reverse route, the branch network identification information (branch port number) accommodated by its own device, and the communication partner's Set the branch network identification information (node number and branch port number of the communication partner) accommodated by the node device, and route information indicating whether to use the forward route or the reverse route. The relay unit 120 may determine the VLAN corresponding to the forwarding branch network that transfers the L2 frame with reference to the VLAN setting table 140.

Industrial applicability

[0073] As described above, the communication system according to the present invention is useful for a communication system in which node devices are arranged so as to connect a main line link in a loop shape. It is suitable for communication systems that transfer frames.

Claims

The scope of the claims

To accommodate a trunk line, two trunk ports and a branch network are accommodated. 1 A plurality of node devices having a plurality of branch ports are connected in a loop shape via the trunk link, and from the branch network accommodated in the own device. In a communication system in which a received layer 2 frame is transmitted via a trunk link to a branch network accommodated in a node device as a communication partner, communication is performed.

The node device is

The first VLAN identifier indicating the forward path of the loop-shaped trunk link that connects the branch network accommodated by the local device and the branch network accommodated by the counterpart node device, and indicates the path reverse to the forward direction A VLAN configuration table in which a second VLAN identifier is configured; and

A control unit that selects whether to transmit the layer 2 frame received from the branch network accommodated by the own device using the forward route or the reverse route;

When a layer 2 frame is received from the branch port, a tagged layer obtained by adding a VLAN tag including the first or second LVAN identifier indicating the route selected by the control unit to the layer 2 frame. When two frames are transmitted through the trunk port accommodating the trunk link of the selected route and a tagged layer 2 frame is received from the trunk port, the first frame set in the VLAN setting table is used. Whether the tagged layer 2 frame received based on the second VLAN identifier and the VLAN identifier set in the VLAN tag of the tagged layer 2 frame is addressed to the branch network accommodated by the own device If the received tagged layer 2 frame is addressed to the branch network accommodated by the local device, the received tagged layer 2 frame Layer 2 frame with the VLAN tag removed is sent to the branch network via the branch port, and if the received tagged layer 2 frame is not addressed to the branch network accommodated by the device, the tagged layer A relay unit for transmitting to the trunk link via a trunk port different from the trunk port receiving the two frames;

A communication system comprising:

[2] The control unit of the node device

When the forward route and the reverse route are usable, a route with a short transfer distance is selected, and the trunk link accommodated by the node receiving the failure notification from another node device or the own device The communication system according to claim 1, wherein an available route is selected when a failure is detected.

[3] The control unit of the node device that is the starting point of the predetermined loop is:

Identify the first and second VLAN identifiers set in advance between the branch networks accommodated by each node device, and the branch networks that communicate using the paths to which these first and second VLAN identifiers are assigned. A control frame for VLAN configuration including information for

The relay unit of the node device as the starting point is

The generated VLAN setting control frame is transmitted to the trunk link via the trunk port accommodating the trunk link in the forward direction or the reverse direction,

The relay unit of the node device different from the node device as the starting point is

When the VLAN setting control frame is received via the trunk port, the VLAN setting control frame is transmitted to the trunk link via a trunk port different from the trunk port receiving the VLAN setting control frame.

The control unit of the node device different from the node device as the starting point is:

If the information for identifying the branch network in the VLAN setting control frame received by the relay unit of the local device contains information indicating the branch network accommodated by the local device, the branch network 2. The communication system according to claim 1, wherein the first and second VLAN identifiers associated with the information for identifying are stored in the LVAN setting table of the own device.

[4] The control unit of the node device different from the node device as the starting point is:

When a failure of the trunk link accommodated by the device itself is detected, a loopback flag indicating that the failure has been detected is set in the control frame for VLAN setting,

The relay unit of the node device different from the node device as the starting point is Sending the VLAN configuration control frame with the return flag set to the trunk link via the trunk port that received it,

The communication system according to claim 3.

[5] In a node device that has two trunk ports that accommodate a trunk link and one branch port that accommodates a branch network, and that constitutes a network in which the trunk link has a loop shape,

A first VLAN identifier indicating the forward path of a loop-shaped trunk link that connects the branch network accommodated by its own device and the branch network accommodated by the node device serving as the communication partner, and a reverse direction to the forward direction A VLA N setting table in which a second VLAN identifier indicating a route is set;

When a layer 2 frame is received from the branch port, a tagged layer 2 frame obtained by adding a VLAN tag including the first or second LVAN identifier indicating the route selected by the control unit to the layer 2 frame Is transmitted through the trunk port accommodating the trunk link of the selected route, and when a tagged layer 2 frame is received from the trunk port, the first and second frames set in the VLAN setting table are transmitted. Whether the tagged layer 2 frame received is addressed to the branch network accommodated by the local device based on the VLAN identifier of 2 and the VLAN identifier set in the VLAN tag of the tagged layer 2 frame. However, if the received tagged layer 2 frame is destined for the branch network that the device accommodates, the received tagged layer 2 frame is used. A layer 2 frame with the VLAN tag deleted is sent to the branch network via the branch port, and the received tagged layer 2 frame is not addressed to the branch network that the device contains. A relay unit that transmits to the trunk link via a trunk line different from the trunk port that received the frame;

A node device comprising:

[6] The control unit includes: When the forward route and the reverse route are usable, a route with a short transfer distance is selected, a failure notification is received, or a failure of the main link accommodated by the device is detected. In some cases, select an available route,

The node device according to claim 5, wherein:

[7] When set as the node device that is the starting point of the loop,

The controller is

The first and second VLAN identifiers set in advance between the branch network accommodated by the node devices constituting the loop-shaped network, and the route to which these first and second VLAN identifiers are assigned. A control frame for VLAN setting including information for identifying the branch network that is used for communication,

The relay unit is

Transmitting the generated VLAN configuration control frame to a trunk link via a trunk port accommodating a trunk link in a forward direction or a reverse direction;

The node device according to claim 5, wherein:

[8] The relay unit includes:

The controller is

If the information for identifying the branch network in the VLAN setting control frame received by the relay unit of the local device contains information indicating the branch network accommodated by the local device, the branch network 8. The node device according to claim 7, wherein the first and second VLAN identifiers associated with the information for identifying are stored in the LVAN setting table of the own device.

[9] The control unit includes:

The relay unit is Send the VLAN setting control frame with the return flag set to the trunk link that has been received,

The node device according to claim 8, wherein: