JPH0530340B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a transmission control system in a loop transmission line, and more particularly to a transmission control system when an abnormality occurs in a double loop transmission system having a detour configuration function.

[Prior art] Japanese Patent Application Laid-open No. 56-40344 discloses that continuous transmission errors due to disconnection of the loop transmission line, failure of the transmission control device (hereinafter referred to as "NCP"), etc. On the other hand, the total of two NCP pairs adjacent to each other is 4
The test data was transmitted to a loop (small loop) composed of NCPs, and the test data was sent.
If the test data does not return within a certain period of time, the NCP determines that there is an abnormality in the small loop,
A loop transmission system is disclosed that configures a detour for data transmission to a paired NCP. However, in the above transmission system, if a failure occurs in the detour transmission path between a pair of NCPs while there is no failure in the loop transmission path or the NCP, this failure will not be detected. If a failure occurs on the loop transmission path in this state, there is a problem in that the transmission function of the system is interrupted due to the detour path failure (hereinafter referred to as an "affecting failure"). This will be explained in detail below.

FIG. 1 shows the overall configuration of the loop transmission system. The system has loop transmission lines 1 and 2 that transmit information in opposite directions, and NCPs 11 to 14 and 21 to 2 are provided on the loop transmission lines 1 and 2.
4, and there is a detour route 41 between the paired NCPs.
-44 and 51-54. Further, processing devices 31-34 are connected to each NCP pair by bidirectional transmission lines 61-64 and 71-74 as shown in the figure.

Now, when the loop transmission lines 1 and 2 and each of the NCPs are in a normal state, it is assumed that a failure A occurs in the detour paths 42 and 52 between the NCPs 12 and 22, making transmission impossible (second (See Figure A). In this state, the failure A has no effect on the transmission on the loop transmission lines 1 and 2 and is not detected. Second
In the state shown in Figure A, further, NCP15,
Loop transmission lines 1 and 2 between 16 and between 25 and 26
It is assumed that failure B occurs during this period, and transmission becomes impossible during this period (see FIG. 2B). In this state NCP
24 transmits a message on the loop transmission line 2, the message does not return to the source NCP 24 due to the failure B. Because the messages they send are not returned,
NCP24 detects that there is an abnormality on the transmission path,
It becomes the source of the small loop check signal 301
and further requests the NCP 14 to transmit a small loop check signal 303. NCP2
The NCP 25, which received the small loop check signal 301 from the NCP 4, sends the signal 301 to the NCP 15 and becomes the source of the small loop check signal 302, but the signal 302 is not the source due to the failure B. I will not return to NCP25. Similarly, the small loop check signal 304 transmitted by NCP13 also
It won't come back to 3.

Through the above process, the NCPs 13 and 25 that have detected an abnormality on the small loop are routed to the detour 53 and
and 45, so that from then on, the message is not sent to the loop transmission path, but is sent to the detour path. Furthermore, the NCPs 21 and 16 also detect abnormalities on the small loops and configure detours 41 and 56 (see FIG. 3). In addition, the NCP that configured the detour
NCPs other than 13, 25, 21, and 16 recognize that they can transmit messages to their neighboring NCPs by receiving the small loop check signals they sent back, and continue to use the loop transmission path. Send a message. In this state,
The system has been divided into two parts, C and D, and transmission between the two parts C and D is no longer possible. This is because, although transmission is actually possible between the two portions C and D, they are separated because unnecessary detours 41 and 53 are constructed due to the failure A. It is.

As mentioned above, in the system disclosed in Japanese Patent Application Laid-Open No. 56-40344, if a failure occurs on the detour path, a failure on a new transmission path causes failure even though transmission is actually possible. Regardless, there is a problem that the system is divided and the transmission function is degraded.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to solve the above-mentioned problems in the conventional loop transmission system, and to solve the problem in the case where a failure occurs in the detour in a double loop transmission system. Furthermore, it is an object of the present invention to provide a transmission control method that reconfigures the transmission line so that the system will not be interrupted even if a failure occurs in the loop transmission line or other detour.

[Summary of the invention]

The main point of the present invention is to send a received message to a double loop transmission path and a pair of NCPs located on the transmission path and forming a detour with each other, and at the same time transmit the received message to the detour. The point is that it is configured to have a sending function.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings.

The system to which the present invention is applied is as shown in FIG. 1 above. FIG. 4 shows an example of messages transmitted for transmission path reconfiguration according to the present invention. A flag (F) 81 indicating that the message 80 is the beginning of the message, and a function code (FC) corresponding to the data content and function.
82. Address of the NCP that created and sent the message (source address: SA) 83. Source NCP
serial number (CC) of each outgoing message 84,
Detour flag (LF) 85, detour counter (LC) 8
6, data 87, and a flag (bottom) 88 indicating the end of the message. Here, the detour flag 85 indicates the detour state of the message 80 and takes two values of "0" and "1". When this value is "1", the detour state of the message 80 is
It is assumed that the NCP that receives 0 sends out the message as is on the transmission path unconditionally. Also,
This detour flag is inverted by the NCP forming the detour and the NCP opposite the source NCP. The detour counter 86 indicates the number of times a message has been detoured, and messages whose value reaches 3 or more are deleted.

Assume that the system is now in a state where a failure A has occurred on the detour path and a failure B has occurred on the loop transmission path, as shown in FIG. Consider the case where a function code corresponding to the contents of is received.

The NCP 24 sets the function code in the FC section 82 of the message format shown in FIG. 4, and sets the data in the Data section 87. Also, LF section 8
5. The LC section 86 is set to "0" as its initial value, and then sent to the loop transmission line 2 in the form of the message as shown in FIG. NCP2 that received this message 1000
5 inverts the detour flag of the message 1000 (from "0" to "1") and increments the detour counter by 1 (0
→1) and send it to the detour route 45, and at the same time set the detour counter to 1 while leaving the detour flag as it is (“0”).
The message 1002 set to 1 is sent out onto the loop transmission line 2. Taking the former detour 45,
When the message 1000 transferred to the loop transmission path 1 via the NCP 15 passes through the NCP 14 corresponding to the source NCP, the detour flag is inverted (from "1" to "0") by the NCP 14 as described above. Furthermore,
When the message 1000 reaches NCP13,
Similar to the NCP 25, the NCP 13 inverts the detour flag (from "0" to "1"), increments the detour counter by 1 (from 1 to 2), and sends the result to the detour route 53.
The message 1001 with the detour counter set to 1 is sent onto the loop transmission line 1 with the detour flag unchanged (“0”). The message 1000 that returned to the loop transmission path 2 via the detour path 53 is the NCP.
24, the NCP 24 detects from the sender address of the message that it is the message it sent, and deletes the message.

On the other hand, the message 1002 sent from the NCP 25 is due to the failure B on the loop transmission line 2.
It is not transmitted to NCP26.

Furthermore, the message 1001 sent from the NCP 13 onto the loop transmission path 1 is sent to the NCP 12,
It reaches NCP16 via 11th, 18th and 17th. NCP16, which makes up the detour, is
Similar to NCP13 and NCP25, invert the detour flag of sent message 1001 (“0” → “1”)
At the same time, the message with the detour counter incremented by 1 (from 1 to 2) is sent onto the detour route 56, and at the same time, the detour counter is increased by 1 while the detour flag remains unchanged (“0”).
The message 1003 set to 1 is sent onto the loop transmission line 1. The message 1001 that passed through the former detour path 56 and moved to the loop transmission path 2 is transmitted to the NCP
It reaches NCP21 via 26th, 27th, and 28th. The NCP 21 configuring the detour route inverts the detour flag of the received message 1001 (from "1" to "0") and increases the detour counter by one. As a result, the detour counter becomes 3, so
The NCP 21 does not send the message to the detour or the loop transmission path 2, but erases it from the transmission path. By erasing messages in the NCP 21, it is possible to prevent messages from being duplicated and transmitted on the loop transmission path.

On the other hand, the message 1003 sent from the NCP 16 is due to the failure B on the loop transmission line 1.
It is not transmitted to NCP15.

(See Figure 3). In addition, the above-mentioned detour
The NCPs 13, 16, and 21 set the detour counter of the message sent on the loop transmission path to 1, so that, for example,
In Figure 5, the source of the message is NCP1
Even in the case of 4, it is possible to prevent unnecessary messages from being transmitted redundantly on the loop transmission path. In this case, the NCP 13 receives a message whose detour counter value is 0 from the NCP 14. The NCP 13 sends the message to the detour path 53 and at the same time sends the message with the detour counter set to 1 onto the loop transmission path 1. Thereafter, as described above, when it reaches the NCP 21, it is erased.
Therefore, even in this case, the message sent from NCP 13 to loop transmission line 1 is duplicated with the message sent from NCP 13 to loop transmission line 1.
23, 24, etc. can be prevented from being transmitted.

After all, in the above embodiment, the message 1000 transmitted from the NCP 24 reaches the NCP 25 via the loop transmission path 2, and from there the message 1000 is transmitted via the detour path 4.
5 to loop transmission line 1, NCP15,
Same 14, Same 13, Same 12, Same 11, Same 18, Same 1
7 to reach NCP 16, from here it passes through detour 56, moves to loop transmission path 2 again, and connects to NCP 16.
26, 27, and 28, while being erased by NCP 21, it has been transmitted to at least one of all paired NCPs, and the failure A on the detour route
In a situation where multiple failures occur, such as failure B on the loop transmission path, it is possible to transmit even parts that would have been separated in the past, and this has the effect of improving the transmission function in the case of multiple failures. .

In the above embodiment, when an abnormality occurs in the detour between NCP12 and NCP22,
We took as an example a case where a failure occurred in the loop transmission line between NCP15 and NCP16, NCP25 and NCP26,
It goes without saying that even if a failure occurs in a different part, it can be dealt with in the same way.

〔Effect of the invention〕

As described above, according to the present invention, a message received by a pair of NCPs that are on a double loop transmission path and that form a detour with each other is sent to the detour, and at the same time is transmitted to the loop transmission path. Since it also has the function of transmitting signals, it has the remarkable effect of making it possible to improve the transmission function in the event of multiple failures.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the overall configuration of the loop transmission system, Figures 2A, B, and 3 are diagrams explaining operations when an abnormality occurs, and Figure 4 is an example of a message format used in the present invention. FIG. 5 is a diagram showing the operation of an embodiment of the present invention. 1, 2...Loop transmission line, 11, 12,..., 2
1,22,...NCP, 41,42...,51,5
2,...Detour, 80,1000~1003...
Message.

Claims (1)

[Claims] 1. A double loop transmission path, a transmission control device provided in a pair on the double loop transmission path, and a detour for transmitting data between the pair of transmission control devices. and when a failure occurs in a part of the transmission path, a transmission control device adjacent to the failure part sends the received data to the detour path, and data transmission is performed by bypassing the failure. In the system,
Loop transmission characterized in that the transmission control device that transmits received data using the detour route is configured so that when sending the received data to the detour route, it also sends the received data to the loop transmission path. Transmission control method in the road. 2. A transmission control device that has a detour counter for the received data and transmits the received data using the detour, increases the value of the detour counter of the received data by a predetermined value, and transmits the received data to the detour. A transmission control system in a loop transmission line according to claim 1, characterized in that: 3. The transmission control device that transmits received data using the detour route stops transmitting the received data when the value of the detour counter reaches a predetermined value. 2. Transmission control method in the loop transmission path described in Section 2. 4. The transmission control device that transmits received data using the detour path transmits the received data with the value of the detour counter set to 1 to the loop transmission path. Transmission control method in the described loop transmission path.