JP3109601B2 - Double loop transmission device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-loop transmission apparatus in which a plurality of communication nodes are connected in a loop via two transmission lines having different transmission directions. In particular, the present invention relates to a double-loop transmission device having a function of enabling a communication node to be added or removed without interrupting communication during operation.

[0002]

2. Description of the Related Art In a conventional double loop transmission apparatus, a communication node is added, for example, after stopping operation of one of the transmission paths of the double loop and connecting the additional communication node to the stopped transmission path. Restart the operation of the stopped transmission line. Subsequently, the operation is performed in such a manner that the operation of the other transmission line is stopped, and the operation is restarted after the communication node to be added is similarly connected. The same applies to the removal of a communication node.

FIG. 5 is a diagram for explaining an example of a procedure for adding a communication node in a conventional double loop transmission device. In the figure, (1) shows a double loop transmission device in which the communication nodes 51, 52 and 53 are connected in a loop via double transmission lines 55A and 55B and are operating, and a communication node before expansion. 54 is shown. Here, the transmission path 55A transmits the message clockwise, and the transmission path 55B transmits the message counterclockwise. In the following description, the communication nodes 51,
The case where 52 and 53 are called existing nodes, the communication node 54 is called a new node, and the new node 54 is added between the existing node 51 and the existing node 53 will be described.

[0004] (2) When adding a new node 54,
First, a state is shown in which a new node 54 is connected to one transmission line 55A of the double loop transmission device. In this procedure, new communication in the double loop transmission device is performed via the other transmission line 55B. Each communication node is instructed to monitor the end of all communications using one transmission path 55A. After the state in which the message does not flow through the transmission path 55A, the new node 54 is connected to the transmission path 55A between the existing nodes 51 and 53. Upon completion of this connection, the use of one transmission path 55A is resumed.

[0005] (3) shows a state in which the new node 54 connected to one transmission line 55A is further connected to the other transmission line 55B. In the same manner, new communication after the new node 54 is connected to one transmission path 55A is performed via the transmission path 55A. Each communication node is instructed to monitor the end of all communication using the other transmission path 55B. After the state in which the message does not flow through the transmission path 55B, the new node 54 is connected to the transmission path 55B between the existing nodes 51 and 53. Upon completion of this connection, use of the other transmission path 55B is resumed.

[0006] The operation state of the double loop transmission device after the addition of the new node 54 is completed by the above procedure is described in (4).
Shown in In the case of removing a communication node, the removal can be performed by a completely reverse procedure.

[0007]

In a conventional extension procedure (removal procedure) in a double loop transmission apparatus, the operation of each transmission line is alternately stopped in order to secure communication in operation as a double loop transmission apparatus. , The communication node is connected (disconnected) to the transmission line which is sequentially stopped. However, each transmission line communicates with a plurality of communication nodes for each transmission direction, and even if a new communication is transferred to the other transmission line when the operation of one transmission line is stopped, the transmission line on one transmission line does not. Until all communication was completed, the operation could not be stopped. That is, not only stopping the operation of one transmission line takes a relatively long time, but also stopping the operation of the other transmission line requires the same time. It took a long time.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a double-loop transmission apparatus capable of performing an extension work or a removal work immediately without interrupting existing communication when a communication node is added or removed. .

[0009]

According to the present invention, there are provided a plurality of communication nodes connected in a loop via two transmission lines having different transmission directions, and each communication node receives a signal from a one-way transmission line. A transmission message transmitted to the one-way transmission path, and transmits a message received from the transmission path in the other direction to the transmission path in the other direction. Setting means for setting a communication node on the upstream side of the transmission path and a communication node on the downstream side of the transmission path, wherein each of the communication nodes, when set as the upstream communication node, the one-way transmission Turn on the return display flag provided in the header information for all the messages received from the path and transmit to the transmission path in the other direction, and when set as the downstream communication node, the transmission path in the other direction Or Among the received message, characterized by comprising the message aliasing control means for transmitting the folded display flag to select only telegram is on the transmission path of the one direction.

[0010]

According to the present invention, the setting means instructs the communication nodes at both ends of the extension section or the removal section, sets a return display flag, and bypasses the message transmitted to the transmission path of the section using the transmission path in the other direction. By doing so, a state is generated in which no telegram flows on the transmission line in that section immediately. That is, this is a method of electrically disconnecting the transmission path of one section for addition or removal, and there is no need to wait for the completion of communication of all sections of one-way transmission, so that communication is not interrupted and immediately. Expansion or removal work can be performed.

[0011]

FIG. 1 is a diagram showing an example of a procedure for adding a communication node in a double loop transmission apparatus according to the present invention. In addition,
In this embodiment, description will be made in accordance with the configuration of the conventional double loop transmission apparatus shown in FIG. 5, but the feature is that the communication nodes at both ends of the extension section control transmission / reception processing corresponding to each transmission path. Configuration. Therefore, in this embodiment, although the basic configuration of each communication node is the same as the conventional one, the function of controlling the transmission / reception processing corresponding to each transmission path is added, so that the symbols are denoted as 11, 12, 13, and 14. . Also,
The case where the communication nodes 11, 12, and 13 are called existing nodes, the communication node 14 is called a new node, and the new node 14 is added between the existing nodes 11 and 13 will be described.

In FIG. 1, (1) shows a state before a new node 14 is added. (2) shows a state where the new node 14 is first connected to one transmission line 55A of the double loop transmission device when the new node 14 is added. In the procedure, an extension instruction is issued to the existing node 13 on the upstream side and the existing node 11 on the downstream side as viewed from the transmission path 55A between the communication nodes where the new node 14 is added. In response to this expansion instruction, the existing node 13 sets the return display flag of the header information to "1" (on) for all messages received from the transmission path 55A,
Control is performed to return the transmission to the transmission path 55B in the reverse direction.
Also, in the existing node 11, although the message originally received from the transmission path 55A is received from the transmission path 55B, it can be identified by the return display flag, so that the return display flag of the header information becomes “1”. Control is performed to return the received telegram to the transmission path 55A and transmit it.
Note that a received message whose return display flag is “0” is transmitted to the transmission path 55B as it is.

According to such a procedure, the message transmission from the existing node 13 to the existing node 11 via the transmission line 55A in response to the expansion instruction is immediately stopped, so that the new node 14 can be replaced without interrupting the communication. 11 and the existing node 13 can be connected to the transmission line 55A. By releasing the extension instruction after the connection is completed, the extension of the new node 14 is completed on the transmission line 55A.

(3) shows a state in which the new node 54 connected to one transmission line 55A is connected to the other transmission line 55B. The procedure is the same as that of the existing node 11 on the upstream side as viewed from the transmission path 55B between the communication nodes where the new node 14 is added.
And an instruction to add to the existing node 13 on the downstream side. In the same manner, the existing node 11 performs control to return to the transmission line 55B and transmits the transmission line 55B.
Control to send back to A is performed.

Therefore, the transmission path 5 from the existing node 11
Since the message transmission to the existing node 13 via the 5B is immediately stopped, the new node 14 can be connected to the transmission path 55B between the existing node 11 and the existing node 13 without interrupting the communication. By releasing the extension instruction after the connection is completed, the extension of the new node 14 is completed for the transmission path 55B following the transmission path 55A.

The operation state of the double loop transmission device after the addition of the new node 14 is completed by the above procedure is shown in (4).
Shown in In the above description, an example is described in which connection to the communication node 55A is performed first, but the same applies to a configuration in which connection to the communication node 55B is performed first. Further, the removal of the communication node can be realized in the same manner by replacing the extension instruction with the removal instruction and executing the reverse procedure.

FIG. 2 is a block diagram showing an embodiment of a communication node used in the double loop transmission device of the present invention. In the figure, the message reception control unit A21 is provided with a transmission line 55A.
And performs a receiving process of the message transmitted clockwise, and sends the message to the message return control unit 22. The message transmission control unit A23 is connected to the transmission path 55A, and performs transmission processing of a message transmitted to the transmission path 55A output from the message return control unit 22. In FIG. 2, the route is indicated by a solid arrow.

The message reception control unit B24 is connected to the transmission path 55B, performs processing for receiving the message transmitted counterclockwise, and sends it to the message return control unit 22. Message transmission control unit B2
3 is connected to the transmission path 55B, and the message return control unit 22
Of the message transmitted to the transmission line 55B output from the transmission line 55B. In FIG. 2, the route is indicated by a broken arrow. Here, the states of the communication nodes 13 and 11 in the addition procedure (2) shown in FIG. 1 are shown in FIGS. 3 and 4, and the operation of the communication nodes 13 and 11 when the communication node 14 is added will be described. .

In FIG. 3, the message return control unit 22 of the communication node 13 transmits a transmission path 55
A control is performed to change the return display flag of the header information of the message received from A from “0” to “1” and to return the message to the transmission path 55B via the message transmission control unit B25. On the other hand, the received message from the transmission path 55B is
The transmission path 55 remains as usual with the return display flag set to “0”.
Send to B.

In FIG. 4, the message return control unit 22 of the communication node 11 transmits a transmission path 55
The message whose return information display flag is "1" in the header information of the message received from B is a message that should be received from the transmission path 55A. Therefore, the return information display flag is changed from "1" to "0". After returning, control is performed to return the transmission to the transmission path 55A via the message transmission control unit A23. On the other hand, a received message whose return display flag is “0” is transmitted to the transmission path 55B via the message transmission control unit B25 as usual.

As described above, by using the addition instruction and the return display flag, the communication nodes 11 and 13 at both ends of the section in which the communication node 14 is added can be in a state in which no message flows only in the corresponding addition section of the transmission line 55A. The communication node can be generated, and the communication node can be added without interrupting the communication. In the communication node 12 for which the extension instruction is not issued, transmission / reception processing is performed for each transmission path regardless of the state of the return display flag.

[0022]

As described above, according to the present invention, for two communication nodes located at both ends of a section where a communication node is added or removed, the return control of a message is performed so as to bypass the transmission path of the section. Accordingly, the communication node can be added or removed immediately without interrupting the communication in operation and immediately after the return control starts. That is, the time required for the extension or removal operation can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a procedure for adding a communication node in a dual loop transmission device of the present invention.

FIG. 2 is a block diagram showing a configuration of an embodiment of a communication node used in the dual loop transmission device of the present invention.

FIG. 3 is a diagram illustrating an operation example of a communication node on the upstream side of a transmission path in a communication node extension section.

FIG. 4 is a diagram illustrating an operation example of a communication node downstream of a transmission path in a communication node extension section.

FIG. 5 is a diagram illustrating an example of a procedure for adding a communication node in a conventional double loop transmission device.

[Explanation of symbols]

 11, 12, 13 Communication node (existing node) 14 Communication node (new node) 21 Message reception control unit A 22 Message return control unit 23 Message transmission control unit A 24 Message reception control unit B 25 Message transmission control unit B 51, 52 , 53 Communication node (existing node) 54 Communication node (new node) 55A, 55B Transmission path

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04L 12/42

Claims (1)

(57) [Claims] 1. A communication system comprising: a plurality of communication nodes connected in a loop via two transmission paths having different transmission directions; each communication node transmits a message received from the one-way transmission path in the one-way transmission path; In a double loop transmission device that transmits a message received from a transmission path in the other direction to a transmission path in the other direction, the transmission path is upstream of the one-way transmission path between two predetermined communication nodes. Setting means for setting a communication node and a downstream communication node, wherein each of the communication nodes, when set as the upstream communication node, receives all messages received from the one-way transmission path. Turn on the return display flag provided in the header information and transmit to the transmission path in the other direction, and when set as the downstream communication node, among the messages received from the transmission path in the other direction, A double-loop transmission device comprising: a message loopback control unit that selects only a message whose loopback display flag is on and transmits the message to the one-way transmission path.