JP2002344462A - Communications device and communication network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communications device an a communication network system which can logically make a physical loop into a tree. SOLUTION: The device has the function for transmitting a frame with an identifier in one direction of a loop from a port 403 connected to a loop-type network, when a frame is received from a port 402, which is not connected to a loop-type network to a communication device 400, and a function for transmitting a frame, whose identifier is eliminated, from one 401 of ports, which are not connected to a loop-type network, when a frame with an identifier is received from the port 403 connected to a loop-type network. When a non-loop side port to be used is switched, a path on a loop is switched.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device used in a network such as an Ethernet, and more particularly to a communication device and a communication network system capable of forming a physical loop into a logical tree. .

[0002]

2. Description of the Related Art When a redundant configuration is used in a network,
A loop is inevitably formed. In the Ethernet, if a loop is included, a broadcast frame or a multicast frame keeps going around the loop, and such useless frames overflow in the network. As a technique for preventing such an increase in the number of frames, a redundant function and a spanning tree protocol are known.

[0003] In the redundant function, when there are two or more paths connecting one communication apparatus to another communication apparatus, a link (logical connection) is disconnected for a path other than the one path, thereby logically. Avoiding loops.
Further, in the spanning tree protocol, a loop is logically avoided by stopping transmission / reception of a looped portion.

On the other hand, in Ethernet, communication devices in a network can communicate with each other, so that all nodes connected to each communication device can communicate with each other.

[0005]

With the use of the redundant function, when a failure occurs in one path whose link has not been disconnected, the switching to another path can be transmitted to the communication device in the loop. And recovery may not be possible depending on the location of the failure.

[0006] Using the spanning tree protocol,
When a failure occurs, it takes time to reconstruct a tree avoiding the failure location. Further, the number of communication devices (the number of pops) included in the loop cannot be increased.

In a loop type network, when terminals outside the loop, which are not recognized by the server or the management terminal, perform a large amount of data communication via the loop, communication between the other terminals via the loop is performed. It becomes difficult. In addition, security problems such as passwords and e-mail contents are stolen in loop-type networks because it is easy for terminals outside the loop that are not recognized by the server or management terminal to intercept frames passing through the loop. There are points.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a communication device and a communication network system which can make a physical loop a logical tree.

[0009]

In order to achieve the above object, a communication apparatus according to the present invention, when receiving a frame from a port not connected to a loop type network, connects a frame to which an identifier is added to the loop type network. A function to transmit from the port in one direction of the loop, and a function to transmit a frame with the identifier removed from one of the ports not connected to the loop type network when receiving a frame with an identifier from a port connected to the loop type network. It is provided with.

In the communication network system according to the present invention, when a frame is received from a port that is not connected to a loop in an Ethernet including a physical loop by a redundant configuration, a frame to which an identifier is added is connected to the loop. A function of transmitting a frame with an identifier from a port connected to the loop and a function of transmitting a frame with the identifier deleted from one of the ports not connected to the loop when a frame with an identifier is received from a port connected to the loop. The physical loop is configured using a plurality of communication devices.

[0011]

An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a communication device according to the present invention. The communication device 400 has four ports 401, 402, 4
03,404. Of these, ports 401 and 402
Is a port that is not connected to the loop type network (hereinafter, referred to as a non-loop side port). The non-loop side ports 401 and 402 are connected to a common switching hub 430 via transmission lines 411 and 412, respectively.
The ports 403 and 404 are ports connected to the loop type network (hereinafter, referred to as loop side ports).
The loop-side ports 403 and 404 are connected to transmission lines 413 and 414, respectively, which are part of the loop. A plurality of such communication devices 400 can be connected to form a loop-type network.

The function of the communication device 400 is as follows.

1) When a frame is received from a non-loop side port, a frame to which an identifier is added is transmitted from the loop side port in one direction of the loop. Specifically, the following operation is performed. A frame received by the switching hub 430 from a transmission path (not shown) is transferred by the switching hub 430,
When received by the non-loop side port 401 through the transmission line 411, the communication device 400 adds an identifier A to the received frame, and transmits the frame with the identifier A from the loop side port 403 to the transmission line 413. Yes (Route 4
21). A frame received by the switching hub 430 from a transmission path (not shown) is transferred by the switching hub 430,
When received by the non-loop side port 402 through the transmission line 412, the communication device 400 adds an identifier B to the received frame, and transmits the frame with the identifier B added from the loop side port 404 to the transmission line 414. Yes (Route 4
22).

As described above, the communication apparatus 400 transmits a frame to which an identifier is added from one of the two loop-side ports connected to the same loop-type network in one direction of the loop, and transmits the frame to the other loop-side port. A frame to which another identifier is added is transmitted from the side port in the opposite direction of the loop.

2) When a frame with an identifier is received from a loop-side port, a frame from which the identifier has been deleted is transmitted from one of the non-loop-side ports. In particular,
The following operation is performed. When the loop-side port 403 receives a frame from the transmission line 413, if the frame is a frame transmitted from a main communication device described later, the identifier A is added. The communication device 400 transmits the frame to which the identifier A has been added from the loop side port 404 to the transmission line 414 while the identifier A has been added, and transmits the frame with the identifier removed from the non-loop side port 401 to the transmission line 411. (Path 423). When the loop-side port 404 receives a frame from the transmission line 414, if the frame is a frame transmitted from a main communication device described later, the identifier B is added. The communication device 400 transmits the frame to which the identifier B has been added from the loop side port 403 to the transmission line 413 while the identifier B has been added, and transmits the frame with the identifier removed from the non-loop side port 402 to the transmission line 412. (Path 424).

As described above, the communication device 400 transmits the frame to which the identifier received by one of the loop-side ports is added from the other loop-side port while the identifier is added to the frame. Remove the identifier from and send.

3) It has a redundant function. Specifically, the setting is made so that only one of the non-loop side ports 401 and 402 connected to the common switching hub 430 can be used.

FIG. 2 shows a main communication device according to the present invention.
The main communication device 500 has four ports 401 and 40.
2,403,404. Port 501,
Reference numeral 502 denotes a non-loop side port. The non-loop-side ports 501 and 502 are connected to a common switching hub 530 via transmission lines 511 and 512, respectively.
Ports 503 and 504 are loop-side ports. The loop-side ports 503 and 504 are connected to transmission lines 513 and 514, respectively, which are part of the loop. When a plurality of communication devices 400 of FIG. 1 are connected to form one loop-type network, only one main communication device 500 is inserted into the loop-type network.
Can be used as the end point of the path of the upstream frame and the start point of the path of the downstream frame.

The functions of main communication device 500 are as follows. 1) When a frame is received from a non-loop side port, a frame to which an identifier is added is transmitted from the loop side port in one direction of the loop. Specifically, the following operation is performed. A frame received by the switching hub 530 from a transmission path (not shown) is transferred by the switching hub 530,
When received by the non-loop side port 501 through the transmission line 511, the main communication device 500 adds the identifier A to the received frame, and transfers the frame with the identifier A from the loop side port 503 to the transmission line 513. Send (path 521). A frame received by the switching hub 530 from a transmission path (not shown) is transferred by the switching hub 530,
When received by the non-loop side port 502 through the transmission line 512, the main communication device 500 adds an identifier B to the received frame, and transfers the frame with the identifier B from the loop side port 504 to the transmission line 514. Send (path 522).

As described above, the main communication device 500 transmits a frame to which an identifier is added from one of the two loop-side ports connected to the same loop-type network in one direction of the loop, and transmits the frame to the other side. A frame to which another identifier is added is transmitted from the loop side port in the opposite direction of the loop.

2) When a frame with an identifier is received from the loop side port, the frame with the identifier deleted is transmitted from one of the non-loop side ports. In particular,
The following operation is performed. When the loop-side port 503 receives a frame from the transmission line 513, the identifier A is added to the frame because the frame is a frame transmitted from the communication device 400.
The main communication device 500 removes the identifier from the frame to which the identifier A is added, and transmits the frame from the non-loop side port 501 to the transmission line 511. The frame to which the identifier A is added is not transmitted from the loop side port 504 (path 523). When the loop-side port 504 receives a frame from the transmission line 514, the identifier B is added to the frame because the frame is a frame transmitted from the communication device 400.
The main communication device 500 removes the identifier from the frame to which the identifier B has been added, and transmits the frame from the non-loop side port 502 to the transmission line 512. The frame to which the identifier B is added is not transmitted from the loop port 503 (path 524).

As described above, the main communication device 500 only removes the identifier from the non-loop side port and transmits the frame to which the identifier received at one loop side port is added. There is no transmission from the other loop side port.

Hereinafter, a more specific procedure will be described with reference to FIG.

As shown in FIG. 3, the loop network according to the present invention comprises a main communication device 100, five communication devices 101 to 105 connected in a loop from the main communication device 100 in order, Switching hubs 110 to 115 connected to the communication devices 100 to 105 by two transmission paths, respectively, and each switching hub 110
6 to 120, which are provided with six nodes 120 to 125. The communication device 100 faces the loop side port for transmitting the frame to which the identifier A described in FIG. 2 is added in the clockwise direction in FIG. 3 and the loop side port for transmitting the frame to which the identifier B is added in FIG. Face counterclockwise. The communication devices 101 to 105 face the loop-side port transmitting and receiving the frame to which the identifier A described in FIG. 1 is added in the counterclockwise direction in FIG. 3 and the loop-side port transmitting and receiving the frame to which the identifier B is added. Face clockwise in FIG.

Although the number of nodes attached to the switching hub may be any number, it is assumed here that one switching hub has one node.
Although the number of main communication devices is one, the number of communication devices and the number of switching hubs may be any number.

At the end (not shown) of the node 120 of the switching hub 110 connected to the main communication device 100, a server for connecting the Internet or managing this loop network can be installed. Switching hub 110 connected to main communication device 100
Is considered the root of the tree. On the other hand, a user terminal or the like can be connected to the nodes 121 to 125.

The non-loop-side ports to be used are set in advance in the switching hubs 111 to 115 and the communication devices 101 to 105 by a redundant function so that the switching hub 110 which is the root of the tree can be reached by the shortest path. Switching hub 110 and main communication device 10
0 does not set the selective use of the non-loop side port by the redundant function.

First, the path of an upstream frame will be described.

When a frame is received by the node 121 of the switching hub 111, only the transmission path 131A can be used by the switching hub 111 and the redundant function of the communication device 101. Transmission line 131
A frame is transmitted to the communication device 101 via A. Since the communication apparatus 101 receives this frame from the non-loop side port, the communication apparatus 101 adds the identifier A to this frame, and transmits the frame with the identifier A added thereto counterclockwise from the loop side port. When the frame arrives at the main communication device 100, the main communication device 100 removes the identifier A from the frame, and transmits the frame to the switching hub 110 via the transmission path 130A. The switching hub 110 is an FDB (filtering database)
To determine the destination of the frame, and forward the frame to the node 120.

When a frame is received by the node 122 of the switching hub 112, only the transmission line 132A is available in the switching hub 112 due to the redundant function, so that the switching hub 112 transmits the communication device 102 via the transmission line 132A. Send the frame to Since the communication device 102 receives the frame from the non-loop side port, the communication device 102 adds the identifier A to the frame, and transmits the frame with the identifier A added thereto counterclockwise from the loop side port. When this frame arrives at the communication device 101, the communication device 101 tries to transmit from the loop side port and the non-loop side port as shown by the path 424 in FIG. 1, but the transmission line 131B becomes unusable due to the redundant function. Therefore, only transmission from the loop side port is executed. This frame
The packet arrives at the main communication device 100 in the counterclockwise direction, and is transferred to the node 120 in the same manner as the frame from the node 121 described above.

When a frame is received by the node 123 of the switching hub 113, only the transmission line 132B can be used by the switching function of the switching hub 113, so that the switching hub 113 transmits the communication device 103 via the transmission line 132B. Send the frame to Since the communication device 103 receives the frame from the non-loop side port, the communication device 103 adds the identifier B to the frame and transmits the frame with the identifier B added clockwise from the loop side port. When this frame arrives at the communication device 104, the communication device 104 tries to transmit this frame from the loop side port and the non-loop side port as shown by the path 424 in FIG. 1, but the transmission line 134A is not used due to the redundant function. Since transmission is possible, only transmission from the loop side port is executed. This frame is received by the communication device 105 clockwise.
The communication device 105 also transmits this frame to the path 424 in FIG.
As described above, transmission from the loop side port and the non-loop side port is attempted.
Since A cannot be used, only transmission from the loop side port is executed. This frame arrives at main communication device 100 clockwise. The main communication device 100 removes the identifier B from the frame, and
0B to the switching hub 110. The switching hub 110 determines the destination of the frame and transfers the frame to the node 120.

The frames from the nodes 124 and 125 reach the node 120 via the clockwise upward path in the same procedure.

Next, the path of a downstream frame will be described.

When a frame addressed to the node 121 is received by the node 120 of the switching hub 110, the switching hub 110 refers to the FDB and recognizes that the node 121 exists beyond the transmission line 130A. Therefore, switching hub 110 transmits the frame to main communication device 100 via transmission line 130A. The main communication device 100 transmits the frame to which the identifier A has been added to the route 5 in FIG.
Since the frame is transmitted from the loop-side port as indicated by 21, the frame reaches the communication device 101 via the clockwise downward route.

The communication apparatus 101 transmits this frame from the loop-side port and the non-loop-side port as indicated by the path 423 in FIG. The frame transmitted from the non-loop side port has the identifier A removed. The frame from which the identifier A has been removed is transmitted to the switching hub 1 via the transmission line 131A.
Arrives at 11. The switching hub 111 refers to the FDB and transfers this frame to the node 121.

Even if frames transmitted from the loop-side port sequentially arrive at the main communication device 100 via the communication devices 102, 103, 104, and 105, the path is not applied because the identifier is A, and this frame is not applied. Determines that the loop has made one round, and discards the frame.

The communication device 101 may also be provided with an FDB, and a frame received from the main communication device 100 via a clockwise downward route may determine the destination by referring to the FDB. As a result, the frame addressed to the node 121 is transmitted only from the non-loop side port, and does not go around the loop.

When a frame addressed to the node 122 is received by the node 120 of the switching hub 110, the switching hub 110 refers to the FDB and recognizes that the node 121 exists beyond the transmission line 130A. Therefore, switching hub 110 transmits the frame to main communication device 100 via transmission line 130A. The main communication device 100 transmits the frame to which the identifier A has been added to the route 5 in FIG.
Since the frame is transmitted from the loop-side port as indicated by 21, the frame reaches the communication device 101 via the clockwise downward route.

The communication device 101 transmits this frame from the loop-side port and the non-loop-side port as indicated by the path 423 in FIG. The frame transmitted from the non-loop side port is discarded because the destination does not correspond to all the nodes of the switching hub 111.

Since the frame transmitted from the loop side port reaches the communication device 102, the switching hub 11 transmits the frame in the same manner as the frame addressed to the node 121.
2 to the node 122.

When the communication devices 101 and 102 are also provided with the FDB, the frame addressed to the node 122 transmitted from the main communication device 100 through the clockwise down route is transmitted to the communication device 1.
At 01, the data is transmitted only from the loop side port by the FDB destination determination and reaches the communication device 102. The communication device 102 transmits this frame only from the non-loop side port based on the destination determination of the FDB.

When a frame addressed to the nodes 123 to 125 is received by the node 120 of the switching hub 110,
In the same procedure, the frame is transmitted from the main communication device 100 on the counterclockwise downstream route and reaches the nodes 123 to 125.

To summarize the above-described steady-state operation of the loop type network shown in FIG. 3, a frame path as shown by an arrow in FIG. 4 is formed in a tree shape.

Next, a procedure for switching paths when a failure occurs will be described. Here, the description will be made on the assumption that the transmission path between the communication apparatus 101 and the communication apparatus 102 is physically disconnected.

Each of the communication devices 101 to 105 has a function of logically disconnecting the link of the non-loop-side port close to the failure point among the non-loop-side ports located downstream from the loop-side port. I do. That is, in FIG. 1, if the transmission path 413 is a failure point, the non-loop side port 401 is disconnected, and if the transmission path 414 is a failure point, the non-loop side port 402 is disconnected. This function is called F
This is called an LR (fast link relay) function. Therefore,
When the transmission path between the communication apparatus 101 and the communication apparatus 102 is physically disconnected, the communication apparatus 102 logically disconnects the link on the transmission path 132A by the FLR function.

The communication apparatus 101 originally logically disconnects the link on the transmission line 131B side by the redundant function, and no change occurs by the FLR function. Similarly, the communication devices 103 to 105 also have transmission paths 133A to 135A.
The link on the A side is logically disconnected, and no change occurs due to the FLR function.

In the communication device 102, since the link on the transmission line 132A side is disconnected by the FLR function, the transmission line used for the upstream path in the counterclockwise direction becomes unusable. In order to switch to the upstream path, the link on the transmission line 132B side that has been unused by the redundant function is logically connected. That is, the setting is made so that the non-loop side port 402 can be used in FIG. Similarly, the switching hub 112 logically connects the link on the transmission line 132B side. As a result, the switching hub 112 transmits the frame from the node 122 to the transmission path 132B instead of the transmission path 132A in the normal state.
The frame is transmitted to the communication device 102 via the communication device 102. Upon receiving this frame, the communication device 102 transmits the frame to which the identifier B has been added clockwise from the loop-side port.

When this frame is received by switching hub 110 via main communication device 100, switching hub 110 recognizes that node 122 is beyond transmission line 130B and rewrites the FDB. Therefore, the switching hub 110 transmits a frame addressed to the node 122 from the transmission line 130B, and this frame is transmitted from the main communication device 100 to the communication device 102 via a counterclockwise downward route.

According to the above procedure, the communication device 102 is incorporated in a tree using the down route in the counterclockwise direction and the up route in the clockwise direction, and shifts to the normal operation.
As a result, the path of the frame as shown by the arrow in FIG. 5 is formed in a tree shape.

According to the present invention, a network having a physical loop as shown in FIG. 3 becomes a logical tree as shown in FIGS. Ethernet can be applied to such a tree-structured network. Although FIG. 3 focuses on the loop type network only, from the viewpoint of a large network partially including such a physical loop, since the partial loop can be handled as a tree, the entire loop cannot be handled as a tree. , Ethernet is applicable. In other words, even in a large-scale network having a redundant configuration, Ethernet can be applied if a loop is configured by the communication device of the present invention as shown in FIG. By applying the Ethernet, the bandwidth is increased, the device price is reduced, and the management becomes easier.

In the present invention, since each communication device has the function described in FIG. 1 (the main communication device is shown in FIG. 2), the redundancy of the path in the physical loop is eliminated. Not dependent. That is, the number of communication devices (the number of pops) included in the loop can be freely increased. Further, the number of nodes attached to the switching hub can be freely increased. Therefore, it is easy to construct a network of a scale suitable for the operation purpose.

According to the present invention, frames from all nodes branched from the loop network are transmitted to the switching hub of the main communication device, which is the root of the tree. Therefore, management of the network is facilitated and security is improved.

Further, according to the present invention, since the communication devices (main communication device) on the loop have substantially the same functions, the communication devices having the same configuration logically and easily communicate with the communication device with simple settings. It can be configured to switch to Thus, when it is desired to exchange the communication device and the main communication device, it is possible to logically exchange the communication device without physically changing the arrangement, thereby facilitating the exchange.

[0055]

The present invention exhibits the following excellent effects.

(1) Since a physical loop of a loop type network can be logically formed as a tree, recovery from a failure is easy, the number of pops is large, and security is excellent.

(2) A large-scale network including a physical loop can be realized by Ethernet with a redundant configuration.

[Brief description of the drawings]

FIG. 1 is a functional configuration diagram of a communication device according to an embodiment of the present invention.

FIG. 2 is a functional configuration diagram of a main communication device according to an embodiment of the present invention.

FIG. 3 is a configuration diagram of a loop type network showing one embodiment of the present invention.

FIG. 4 is a diagram showing a frame path when the loop network of FIG. 3 is in a steady state;

FIG. 5 is a diagram illustrating a route of a frame after a route is switched in the loop network of FIG. 3;

[Explanation of symbols]

 100, 500 Main communication device 101-105, 400 Communication device 401, 402, 501, 502 Non-loop side port 403, 404, 503, 504 Loop side port

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5K031 AA11 AA12 CB11 DA03 DA12 5K033 AA08 AA09 DA02 DA15 DB03 EA02

Claims (2)

[Claims] When a frame is received from a port not connected to the loop type network, a function of transmitting a frame to which an identifier is added in one direction of a loop from a port connected to the loop type network, and a function connected to the loop type network. A function of transmitting a frame with the identifier deleted from one of the ports not connected to the loop type network, when receiving a frame with an identifier from the port. 2. In Ethernet (registered trademark) in which a physical loop is included in a redundant configuration, when a frame is received from a port not connected to the loop, a frame to which an identifier is added is transmitted from the port connected to the loop. Multiple communications with a function to transmit in one direction of the loop and a function to transmit a frame with an identifier deleted from one of the ports not connected to the loop when a frame with an identifier is received from a port connected to the loop A communication network system, wherein the physical loop is configured using a device.