JPH02294132A - Loop network transmission control system - Google Patents

Abstract

PURPOSE:To implement the procedure till the communication in a standby system automatically quickly by providing a specific bit field and a specific address field in a transmission frame. CONSTITUTION:The specific bit field of an optional transmission frame entered from an optical module 12 through a changeover switch 14 is detected by specific bit detection circuit 21. When the specific bit is 0, a relay register 16 brings the specific bit of the specific bit field during the passing the logic 1 and writes the transmission opposite station address to the succeeding specific address field. Moreover, the changeover switch 14 switches the operating transmission line to the system B (standby system) and sends a token to the B system transmission line from a token generating circuit 28 in the path of a selector 17, the changeover switch 14 and an optical module 13 to call the opposite station and to instruct the switching of the transmission line. Thus, the communication in the standby system is prepared in the short time automatically.

Description

[Detailed Description of the Invention] "Differential Application Fields" This invention is a loop network system that controls data transmission between each station of a network system having two reverse loop-shaped transmission paths, a working system and a standby system. This relates to a transmission control method.

``Prior art'' Conventionally, the methods of using transmission lines in a double loop network include using two transmission lines A and B as a working system and a backup system as shown in Figure 3 (1), or using two transmission lines as shown in Figure 4. As shown, both are used as active systems. Third
The figure shows a loop network in which a plurality of stations 1 to 6 are connected on reverse double loop transmission lines A and B, and station 1 shows a simple configuration of the station.

The transmission control unit 7 selects one of the two transmission paths A and B, performs access control, etc. of the selected transmission path, and
Other transmission lines are bypassed. The terminal control section 8 is connected to the transmission control section 7 and performs interface control between a terminal or a computer 9 connected to the station and the loop-shaped transmission path. A token frame is circulated on the looped transmission path, and the station that wants to transmit receives the token frame and obtains the right to transmit, erases the token frame and transmits the information it wants to transmit, and when the transmission is finished, the station receives the token. Sends the frame to the transmission path. FIG. 5 shows a conventionally used transmission frame.

FIG. 4 shows a loop network in which a plurality of stations 1 to 6 are connected on reverse double loop transmission lines A and B, with station 1 showing a simple configuration of the stations. The transmission control units 11a and 1lb are connected to the transmission path A. Transmission control is performed for each of B.

The terminal control section 8 is connected to both the transmission control section 118.1lb and the terminal or computer 9 connected to the station 22 and the two loop-shaped transmission lines A.1b. B (particularly two transmission control units).

In the case of FIG. 3, only one set of transmission control unit 7 such as transmission line access control and data buffer is required, so the scale of the device is small.
Since only one transmission line can normally be used, the communication capacity is lower than that shown in Fig. 4.

In the case of Fig. 4, two cans can be used for normal data transmission, so the communication capacity is doubled compared to the former, but two sets of transmission control units are required, which increases the scale of the device. There is a characteristic that

If the method shown in Figure 3 is used and the transmission line is used for the traffic of one transmission line, the station equipment will be economical, but the transmission waiting time may increase due to occasional load peaks. . If the method shown in FIG. 4 is used for the traffic of one transmission line, the increase in transmission waiting time during overload will be eliminated, but two sets of transmission control units will be required, making the station equipment uneconomical.

By diverting part of the communication traffic to the standby system in the event of an overload using the method shown in FIG. 3, it becomes possible to deal with peak loads economically. A method for bypassing traffic to the protection system is to switch the transmission line in use to the protection system in each of a set of stations that wish to communicate, and then transfer data between these stations. However, in the past, an instruction to switch to the backup system was given by receiving a token frame and obtaining transmission rights. For this reason, when the active system is congested and many stations on the upstream side are trying to obtain transmission rights, token frames do not arrive easily at the downstream stations, so they cannot immediately send an instruction to switch to the backup system. First, it has the disadvantage that it takes too much time from the time a communication request occurs until the communication is completed.

``Problems to be Solved by the Invention'' In order to eliminate such conventional drawbacks, the purpose of the present invention is to develop a method of using two loop-shaped transmission lines as active systems, and a method of using two loop-shaped transmission lines as active systems. By taking advantage of the advantages of both methods of dividing the transmission line into active and protection lines, when there is a request to communicate to a specific station on the standby line (called the protection line) during peak load times, etc., the other station can An object of the present invention is to provide a loop network transmission control system that automatically and quickly performs procedures up to communication in the standby system, such as a notification method for communication.

``Means for Solving the Problems'' The loop network transmission control system of the present invention connects a plurality of stations with a working system and a standby system reverse direction double loop transmission path, and tokens circulated on this loop transmission path. In a data transmission system that sequentially grants transmission rights to each station using a frame, a specific bit field and a specific address field are provided in the transmission frame,
Each station controller is equipped with a means to detect its own address in a specific bit in a transmission frame and in a specific address field, and when there is a request for transmission on the protection transmission path, it turns on a specific bit in any transmission frame, and Write the destination address in the special address field, send it, then switch the transmission line to the backup system and send it to the destination station.
While sending a transmission frame containing the message you want to send,
When the other station recognizes that the specific bit is turned on in the specific bit and specific address field and recognizes its own address, it switches the transmission path to be used to the protection system and receives the transmission frame addressed to itself.

Embodiment FIG. 1 shows an example of a transmission frame used in this invention. , a specific bit field SPEF and a specific address field SPEA for one transmission frame shown in FIG.
The difference is that this is added.

If communication is to be performed using the backup system 1 transmission route, a specific pit in the specific bit field is turned on, and the other party's address is entered in the specific address field.

One specific bit is sufficient, but since processing is generally performed one byte at a time, a one-byte specific bit field is allocated for a specific pit.

FIG. 2 shows an example of the configuration of a station used in the method of this invention. Although there is a control line for sending instruction signals from the control circuit l5 to each part, only the control line to the changeover switch l4 is shown because it is difficult to see in this figure. The stations are connected to fiber optic cables IA, IB, 2A, 2B.

Optical fiber cable 1. A and 2A are A-system transmission lines, and optical fiber cables IB and 2B are B-system transmission lines.

The A-system transmission lines IA and 2A are connected to the optical module 12, and the B-system transmission lines IB and 2B are connected to the optical module 13. The input from the transmission line 2A is input to the optical module 2, and after being photoelectrically converted, it is separated into data, data and clock, and the data is output to the signal line 100A and the clock is output to the signal line 100B. Similarly, the input from the two-way transmission path IB is input to the optical module 13, and after being photoelectrically converted, it is separated into data and a clock, and the data is output to the signal line to LA and the clock is output to the signal line 101B.

The signal lines 100A, IOOB, IOIA, and IOIB are input to a changeover switch l4. The current transmission line is A system 1.
The signal line 120 from the control circuit 15 instructs whether to use the B system, the B system, or the loop pack configuration, and the connections of the signal lines are switched depending on the content of the instruction. In the case of active operation in system A, the signal line 100A is connected to the signal line 104, and the signal is transmitted to the relay register 16 and other signal lines 104.
is sent to each circuit connected to the signal line 103A.
is connected to the output line 105 of selector l7. At this time, signal lines 101A and 101B from the B-system optical module l3
are connected to signal lines 102A and 102B, respectively, and the B-system transmission line becomes a backup system and is bypassed. In the case of active operation in system B, the signal line 101A is connected to the signal line 104, and the signal is sent to the relay register 16 and other circuits Z2 connected to the signal line 104, and the signal line 102A is the output line of the selector l7. 105. At this time, the signal lines 100A and IOOB from the A-system optical module 12 are connected to the signal lines 103A and 103B, respectively, and the A-system transmission line becomes a backup system and is bypassed. In the loopback configuration, transmission line 2A. If there is a failure on the 2B side, signal line 101
A is connected to the signal line 104, and the signal is sent to the relay register l6.
and other circuits connected to the signal line 104, and the signal line 103A is the output line 10 of the selector l7.
Connected to 5. If there is a failure on the transmission lines IA, IB, the signal line 100A is connected to the signal line 104, and the signal is transferred to the relay registers 1. 6 and other circuits connected to the signal line 104, and the signal line 102A is connected to the output line 105 of the selector l7.

The output line 104 from the changeover switch 14 is connected to a relay register l6, a delimiter detection circuit l8, and a token detection circuit 19.
, specific bit}4 output circuit 21, specific address field comparison circuit 22, self-addressed add detection circuit 23, and response reception detection circuit 24. Normally, the selector 17 selects the signal line 132, and the signal entering the signal line 104 flows from the selector l7 to the changeover switch 14 via the relay register l6, and is sent out to the transmission line.

When the head of the transmission frame is recognized by the delimiter detection circuit l8, the specific bit detection circuit 21, the specific address field comparison circuit 22, the own address detection circuit 23, and the response reception detection circuit 24 become operational. After that, when the specific bit field and specific address field are received, if there is a transmission request on the protection transmission line and the specific bit is 0, the specific bit of the specific bit field passing through relay register l6 is set to 1 (on). ) and instructs the relay register l6 to write the destination station address in the specific address field. Conversely, a specific bit is 1
If the specific address field is the own stainless steel address, instruct the relay register l6 to set the specific pit currently passing through to 0, and then switch the switch l4.
to switch the transmission line used to the backup system.

When a normal address field is received, the own address detection circuit 23 compares it with the own address. If the address is addressed to the own station, a coincidence output is output to the signal line 106, and when the gate circuit 25 is opened, the received frame is sent to the reception buffer 26 via the signal line 107. Thereafter, the control circuit 15 instructs the relay register 16 to write a response bit into the response field passing through.

When the token is detected by the token detection circuit 19, the control circuit 15 allows the token to pass through the relay register 16 as is when there is no transmission request, but instructs the relay register 16 to erase the token when there is a transmission request. Thereafter, the selector 17 is switched to the signal line 130, and the frame from the transmitting buffer 27 is sent to the changeover switch 141, sent to the working optical module, and sent out over the transmission line. Thereafter, the selector 17 is changed to the signal line 131, and the token is sent from the token generation circuit 28 to the transmission path through the same route as the transmission frame. Thereafter, the selector l7 switches to the signal line 132 and relays the signal from the relay register 16. Note that information transmission, instructions, etc. between each circuit are performed by the control circuit 15.

Next, the operation of data transmission control by switching the transmission path when a transmission request is made on the protection transmission path when the transmission path is overloaded will be described. The A-system transmission line is assumed to be the active system.

First, the operation of the transmitting station will be described. First, a notification is sent to the destination using specific bits and a specific address field of an arbitrary transmission frame (destination is an arbitrary transmission frame). For this purpose, from the optical module l2 to the changeover switch l
When the delimiter detection circuit 18 detects the delimiter of any transmission frame that enters the signal line 104 through the signal line 104, the delimiter detection circuit 18 detects a specific bit detection circuit 21, a specific address field comparison circuit 22, a self-destination address detection circuit 23, and a response reception detection circuit. Circuit 24 becomes operationally deaf. after that,
When the specific bit field is detected by the specific bit detection circuit 21 and the specific bit is 0, the control circuit 15 sets the specific bit of the specific pit field passing through the relay register 16 to 1, and sets the destination station in the subsequent specific address field. Relay register l to write address
6. Relay register l6 writes specific bits and specific addresses. If the content of the destination address field subsequently entered into the own address detection circuit 23 is the own station, the gate 25 is opened using the signal line 106, and (a portion of the transmission frame) is put into the reception buffer 26. If the frame is not addressed to itself, the received frame passes through a relay register l6, a selector l7, a changeover switch l4, and is output from the optical module l2 through a transmission line κ2. Thereafter, the control circuit 15 instructs the changeover switch 14 to switch the transmission line to be used for the B system 12. Thereafter, one transmission path is monitored, and the token detection circuit 19 and token monitoring timer 29 check for the arrival of a token for a certain period of time. When a token arrives, the token detection circuit l9
is detected, and the transmission operation begins.

The token has not arrived for a certain period of time, and the token monitoring timer 29
When the timer 29 expires, the timer 29 is reset, the signal line of the selector 17 is selected as 131, and the token generation circuit 28
Token from selector 17, selector switch l4
, and is sent to the B-system transmission line via the path of the optical module l3. After sending, the selector 17 is switched to the signal line 13.2, and the process moves to relay reception. The transmission path is monitored again, and the token detection circuit l9
If the token is detected in , move on to the next sending operation. In the transmission operation, the selector l7 is changed to the signal line 130, and the transmission request transmission frame in the transmission buffer 27 is transferred to the signal line 13.
0, the selector l7, the f-word line 105, and the changeover switch l4, and send it to the switched transmission line 2B.

After sending the transmission frame, selector l7 is connected to signal line 13.
Set to 2 to relay and receive. It then waits for a response from the destination. Response is response reception detection circuit 2
4, and if there is no need for communication thereafter, the control circuit 15 instructs the changeover switch 14 to switch the used transmission path, and returns the used box sending path to the original A-system transmission path <<2>.

Next, the operation of the receiving station will be described. A frame with a specific focus written to 1 on the A-system transmission path is received by a station that matches the address written in the specific address field. At that station, the received frame that has entered through the optical module l2 and the changeover switch 14 is checked by the specific bit detection circuit 2l, and when it recognizes that it is 1, the control circuit 15 sends the relay register l6 the current passing frame. It instructs the specific bit to be set to 0, and instructs the changeover switch 14 to switch the transmission path to be used when the transmission frame being received has finished passing through. Switches the transmission path used to the B system and waits for the transmission frame addressed to itself to be received. When the reception of the self-addressed frame is detected by the self-address detection circuit 2:3, the self-address detection circuit 23 opens the gate 25 via the signal line 106 and causes the received frame to be taken into the reception buffer 26. After the capture is completed, the selector 17 is set to the signal line 133, and the response is sent from the response transmission circuit 31 to the optical module l3 via the signal line 133, selector 17, signal line 105, and changeover switch 14, and sent to the B-system transmission line. . After the transmission is completed, the selector 17 is changed to the signal line 132, and if there is no need for later communication, the changeover switch 14 is changed to the original A-system transmission line.

``Effects of the Invention'' As explained above, according to the present invention, in a network having a double-loop transmission path for active and backup systems, any transmission frame flowing through the transmission path currently in use can be used. By immediately calling the other station to communicate on the protection transmission line and instructing it to switch the transmission line, communication on the protection system can be automatically prepared in a short time. System communication can be performed with high performance.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a transmission frame used in this invention, FIG. 2 is a block diagram showing an example of a station configuration in this invention system, and FIGS. 3 and 4 are respectively conventional double-loop transmission systems. FIG. 5 is a block diagram showing a loop network system using a transmission line, and FIG. 5 is a diagram showing a conventional transmission frame.

Claims (1)

[Claims] (1) In a data transmission system in which multiple stations are connected by a working and backup reverse double-loop transmission line, and each station is sequentially given the right to transmit using a token frame circulating on the loop-shaped transmission line, A specific bit field and a specific address field are provided in the frame, and each station is provided with means for detecting the specific bit in the transmission frame and its own address in the specific address field, and there is a request for transmission on the backup transmission path. At the same time, turn on a specific bit in any transmission frame, write the destination address in the specific address field in that frame, and send the message, then switch the transmission path to the backup system and send the message you want to send to the destination station. When the destination station recognizes that the specific bit is turned on and its own address in the specific bit and the specific address field, it switches the transmission path used to the backup system and receives the transmission frame addressed to itself. A loop network transmission control method featuring: