JPS6126346A - Controlling system of loop network - Google Patents

Abstract

PURPOSE:To perform a shift to loop back and one-way loop conditions with high reliability in a loop network composed of two one-way circuits when a fault occurs in the transmission system. CONSTITUTION:An input signal level detecting circuit and frame synchronism detecting circuit are provided in each node 1-4 and, when these detecting circuits detect a fault in circuits, the signal of a normal loop is turned back while supplying signals to the loop, in which the fault is detected. When, for example, the clockwise loop between the nodes 2 and 3 is faulty, the turned- back signal from the node 3 is received at the node 4 and the synchronism of the clockwise loop is established. Then inputs of the clockwise loop are outputted to the clockwise loop and inputs of the counterclockwise loop are outputted to the counterclockwise loop. Thereafter, the synchronism between the node 4 and center node 1 is established in the same way and two transmission systems in which the sections between the remote node 4 and remote node 3 are set to turning-back modes are established.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is a method for transmitting signals in left and right directions to a plurality of nodes that can be connected to computers and their terminal devices that are distributed within the premises of a factory, research institute, office, etc. This is related to PAS control of a loop network that communicates between various terminal devices connected to nodes by two loop-shaped transmission lines that propagate.Conventional configuration and its problems Figure 1 shows a diagram of a loop network. A typical configuration is shown. A control communication station 1 (hereinafter referred to as a center node) performs frame circulation at a constant cycle, synchronizes the transmission system, and manages the connection status of communication stations (hereinafter referred to as nodes). ) and other nodes 2, 3, 4.
(Nodes other than the center node are referred to as remote nodes) are connected to two loop-shaped transmission lines 101 and 102 on the left and right, and various processing devices (hereinafter referred to as terminals) connected to each node are connected to loop transmission lines 101 and 102. They can send and receive information to each other via the system. Note 11-1
6 is a terminal connected to the node.

At this time, there are various methods for controlling the exclusive right of the transmission path when a node transmits information, but these are not essentially related to the present invention and will not be discussed in detail.

In such a loop network, we will explain how recovery and processing are performed when a failure occurs in the transmission system.

FIG. 2 shows a block configuration of a conventional transmission control circuit of a remote node, which operates in a conventional manner. The signal on the clockwise transmission line 101 is transmitted to the clockwise input signal level detection circuit 2.
The presence or absence of a signal is monitored by 0. The signal on the clockwise transmission path 101 is processed by the clockwise transmission path decoder 21 . Transmission line switching circuit 22. Through the clockwise transmission path receiving circuit 23, the CPU 2
4, where it is processed and sent to the terminal as necessary.

The signal sent to the CPU 24 is sent to the clockwise transmission line transmission circuit 25. The clockwise transmission speed is 10 through the clockwise transmission line encoder 26.
1 and transmitted to adjacent nodes.

On the other hand, the presence or absence of a signal on the counterclockwise transmission path 102 is also monitored by the counterclockwise input signal level detection circuit 30, and the signal on the counterclockwise transmission path 102 is detected by the counterclockwise transmission path decoder 31. Transmission line switching circuit 22° counterclockwise transmission line receiving circuit 33
The data is transmitted to the CPU 24, processed, and sent to the terminal as necessary. The signal transmitted to the CPU 24 is sent to the left transmission line transmission circuit 35. The signal is passed through the counterclockwise transmission path encoder 32, placed on the counterclockwise transmission path 102, and transmitted to the adjacent node.

The transmission line switching circuit 22 switches the transmission line in response to a failure in the transmission line system. The logic processing circuit 28 includes a clockwise input signal level detection circuit 20. The presence or absence of a signal on the transmission path obtained from the left-handed input signal level detection circuit 30 and the right-handed transmission path decoder 21. The frame synchronization obtained from the counterclockwise transmission line decoder 31 and the instructions from the CPU 24 are logically processed, and instructions are issued to the transmission line switching circuit 22, the clockwise transmission line bypass switch 27, and the counterclockwise transmission line bypass switch 29 for transmission. Switch roads.

FIG. 3 is a block diagram of a conventional transmission control circuit of a center node. The difference from the remote node is that in order to make the Rougoux circular delay an integral multiple of the frame period, a decoder 21° 31 and a transmission path switching circuit 2 are installed for the left and right image transmission systems.
Components that are the same as those in the configuration diagram of the frame arrayed node between 20 and 20 are given the same numbers and their explanations will be omitted.

FIG. 4 shows the state of the logic processing circuit 28 of the remote node.
FIG. 5 describes the state of the logic processing circuit of the center node, and the transmission path is switched according to this diagram. The condition is
Clockwise transmission line input signal level (presence/absence), counterclockwise transmission line input signal level (presence/absence), clockwise frame synchronization (normal/out of synchronization).

There are 64 combinations of clockwise frame synchronization (normal/out of synchronization) and instructions from the CPU (both loops normal, 9 clockwise loops, counterclockwise loop, loopback), but there is no transmission line input signal level. ) and frame synchronization (normal), which is an impossible combination, so in reality,
The remote node changes from state R1 to R1 as shown in FIG.
5 in 15 ways, and the center node in 9 ways up to state C1 or 09 as shown in FIG. Other combinations are ignored. The reason why the state descriptions of remote nodes and center nodes are different is that the input to the center node represents the signal state at the most downstream of the loop, that is, the state of the loop transmission system, whereas the input to the remote node represents the signal state in the middle of the loop. This is because the state of the loop transmission system is not necessarily described correctly and the degree of freedom is greater than that of the center node.

In Fig. 4, state R1, state R2, and state R3 are all normal for the left and right transmission lines, but the states of the loop transmission system include the possibility of a normal state, a clockwise transmission line segment loop, and a counterclockwise transmission line segment loop. Therefore, in response to instructions from the center node, the transmission line enters a normal state, a clockwise transmission line segment loop state, and a counterclockwise transmission line segment loop state, respectively. State R4 and state R5 are both out of frame synchronization of the counterclockwise transmission line, and are similar transmission line states, and there is a possibility of both a clockwise loop and a loopback. Determine the backward direction and enter the clockwise loop and loopback relay states, respectively. Status R6
In state R7, the counterclockwise transmission line signal is disconnected, and the transmission line is in the same condition, and both the clockwise loop and loopback are audible, so the clockwise loop and loopback are set according to instructions from the center node. and enters the clockwise one-loop and loop-back states, respectively.

Conditions R8 and R9 are both clockwise transmission line frame synchronization out of synchronization, and are similar transmission line conditions, and there is a possibility of both a counterclockwise loop and a loop bank. , and enter the counterclockwise loop and loopback relay states, respectively. In state R10, the left and right transmission paths are out of frame synchronization, and access from the node is impossible. State R11 is a state in which the clockwise transmission line frame synchronization is lost, the counterclockwise transmission line signal is cut off, and access from the node is disabled. Status R12
In state R13, the clockwise transmission line signal is disconnected, and both are similar transmission line conditions. Since both the counterclockwise loop and the loopback are possible, the counterclockwise loop and loopback are performed according to instructions from the center node. Determine and enter the left turn loop and loopback return state, respectively. Status R1
4 is a state in which the counterclockwise transmission line frame synchronization is out, the clockwise transmission line signal is disconnected, and access from the notebook is impossible. Status: @
R15 is in a state where the left and right transmission line signals are disconnected and cannot be accessed from the node.

In FIG. 5, state C1 is a normal state.

In state C2, the counterclockwise transmission path frame synchronization is out of synchronization and the clockwise loop is in a state. State C3 is a state in which the counterclockwise transmission line signal is disconnected and a clockwise loop is in progress. In state C4, the clockwise transmission path frame synchronization is out of synchronization and the clockwise transmission line is in a counterclockwise loop state. Condition C5
The left and right transmission lines are out of frame synchronization and are in a loopback state. In state C6, the clockwise transmission line frame synchronization is lost and the counterclockwise transmission line signal is disconnected, resulting in a loopback state, and the center node itself performs loopback. State C7 is a state in which the clockwise transmission line signal is disconnected and a counterclockwise loop is in progress.

In state C8, the counterclockwise transmission line frame synchronization is lost and the clockwise transmission line signal is disconnected, resulting in a loopback state, and the center node itself performs loopback. State C9 is a system down state in which the left and right transmission line signals are disconnected.

If a failure occurs in the transmission system, the center node grasps the status of the loop transmission system as shown in Figure 5, switches the status of the transmission system, and then notifies the remote node of the status of the loop transmission system using normal communication procedures. do. On the other hand, the remote node learns the state of the loop transmission system and switches the transmission path, as shown in FIG. 3, according to its own information and information from the center node. However, in the loopback state, two frame aligners are connected to one loop, and there are two synchronization systems in one loop, and a slip occurs due to the phase shift of the surface synchronization source, so the center node is in the loopback state. When he learned this, he stopped the operation of one of the two frame aligners. It is free to choose which frame aligner to stop.

Now, suppose that a failure occurs in the transmission system at the location marked with an X in the system shown in FIG. The failure recovery process in this case will be explained. Possible causes of transmission system failures include transmission line disconnection, node relay function failure, and local noise on the transmission line.
There are three possible phenomena: clockwise transmission line failure (Fig. 6), left-hand transmission line failure (Fig. 7), and one-way transmission line failure (Fig. 8). Note that the location where the failure occurs is between the remote nodes 2 and 3 in both cases, but is not limited thereto. There may be many more cases in which the phenomenon occurs suddenly, but since it is possible to describe it by a combination of the three conditions above, failure recovery processing in the three cases described above will be described.

In the case of FIG. 6, the center node detects frame synchronization on the clockwise transmission line and enters state C4 to perform counterclockwise loop transmission. Therefore, the counterclockwise loop is used to notify the remote node that it is in the counterclockwise loop transmission state. Since each remote node knows that remote node 2 is in state R1° R2 or R3, remote node 3 is in state R12 or R13, and remote node 4 is in state R8 or R9, If the notification from the center node is a possible state of the own node, the node transits to each state. That is, remote node 2 transits to state R3, remote node 3 transits to state R12, and remote node 4 transits to state R8, and as a result, a counterclockwise transmission line segment loop is formed.

In the case of FIG. 7, the center node detects a loss of frame synchronization on the counterclockwise transmission line and enters state C2 to perform clockwise loop transmission. Therefore, a clockwise loop is used to notify the remote node that it is in a clockwise loop transmission state. Remote node 2 is in state Re.

Any of R7, remote node 3 is in state R1°R2,
R3, remote node 4 is in state R1, R2,
Since each remote node knows that the node is in one of R3, if the notification from the center node is a possible state of the local node, the node transitions to each state. That is, remote node 2 is in state Re, remote node 3 is in state R2,
The remote node 4 transits to state R2, and as a result, a right-handed transmission path loop is formed.

In the case of FIG. 8, the center node detects frame synchronization of the left and right transmission paths, enters state C5, stops the operation of one of the frame aligners, and performs loop batter transmission. ° Therefore, both the left and right loops are used to notify the remote node that it is in a loopback state. Remote node 2 is in state R6 or R7, remote node 3 is in state R1
2, R13, remote node 4 is in state Rs
, R9, and therefore, if the notification from the center node is a possible state of the local node, the node transits to each state.

That is, remote node 2 is in state R7, remote node 3 is in state R7, and remote node 3 is in state R7.
is in state R13, remote node 4 is in state R9,
As a result, a loopback is formed.

Further, recovery from these failure states to a normal state can be performed by communication from the center node to each remote node.

In this way, it is possible to perform recovery processing in the event of a transmission system failure, loop bank, and return to a normal state from a one-loop state. However, loopback.

Recovery processing when a transmission system failure occurs in one loop is performed by notification from the center node in a state where the transmission system between the center node and each remote node has not been established. Processing is performed using a one-sided transmission path from the center node to the remote node adjacent to the fault location, so it is impossible to confirm whether notifications from the center node have been reliably transmitted, resulting in a lack of reliability. It has the following drawback.

OBJECTS OF THE INVENTION An object of the present invention is to provide a RAS control device that can perform loopback and transition to a single-loop state in the event of a transmission system failure with high reliability in any of the above situations.

Structure of the Invention According to the present invention, each node has an input signal level detection circuit and a frame synchronization detection circuit for both clockwise and counterclockwise loop transmission lines, and when a drop in the input signal level or frame synchronization is detected, While supplying the signal to the loop transmission line on the other side, the signal of the normal loop transmission line is looped back, and when the input signal level and frame synchronization return to normal, the signal looping is stopped. After establishing a transmission system between the center node and remote nodes by outputting the input of the left-handed loop transmission route to the transmission route, the center node notifies the remote node that it is in a normal state.

An embodiment of the present invention will be described below in which a transition is made between one loopback state and one loop state to recover from a transmission system failure and return to a normal state. The configuration of the loop network and the configuration of the transmission control circuit are the same as those shown in FIGS. 1, 2, and 3 in the conventional example, so the same numbers are given and some explanations are omitted.

Suppose now that a failure occurs in the transmission system at the location marked with an X in the loop network of FIG. The failure recovery process in this case will be explained. Possible causes of transmission system failures include transmission line disconnection, node relay function failure, and local noise on the transmission line.As a phenomenon, clockwise transmission line failure (Figure 5)
There are three possible cases: , counterclockwise transmission line failure (Figure 6), and nine-way transmission line failure (Figure 7). Note that the location where the failure occurs is between the remote nodes 2 and 3 in both cases, but is not limited thereto. There may be many more cases in which the phenomenon actually occurs, but since it is possible to describe the above three combinations of states, failure recovery processing for the above three cases will be explained.

In the case of FIG. 6, center node 1. Remote node 3. Each remote node 4 detects clockwise transmission path frame synchronization loss. In the present invention, when out-of-frame synchronization and signal interruption are detected, the signal is transmitted to the normal loop, and the signal from the normal loop transmission path is looped back to the loop transmission path on the detected side, so that the input signal level and frame synchronization are corrected. When the signal returns to normal, it stops returning the signal, and the input of the clockwise loop transmission line is output to the clockwise loop transmission line, and the input of the counterclockwise loop transmission line is output to the counterclockwise loop transmission line.

If a normal loop transmission line signal is looped back to the detected loop transmission line, remote node 4 first receives the signal looped back by remote node 3, establishes frame synchronization on the clockwise transmission line, and performs clockwise loop transmission. The input of the loop transmission line is output to the clockwise loop transmission line, and the input of the left loop transmission line is output to the left loop transmission line. Next, the center node 1 receives the signal relayed by the remote node 4 and establishes frame synchronization on the clockwise transmission path, and the input of the clockwise loop transmission path goes to the clockwise loop transmission path.

The input of the counterclockwise loop transmission line is output to the counterclockwise room transmission line. In this way, frame synchronization is performed sequentially from the upstream remote node 4. A counterclockwise loop transmission system is established with the center node, as shown in FIG. Two transmission systems are established.

In the case of FIG. 7, center node 1. Each remote node 2 detects frame synchronization in the counterclockwise transmission system. As in the case of Figure 6, center node 1, remote node 2
If the signal is looped back from the normal loop transmission line while supplying the signal to the loop transmission line on the detected side, the center node 1 receives the signal looped back by the remote node 2 and performs frame synchronization on the left side transmission line. Once established, the input of the clockwise loop transmission line 9 is output to the clockwise loop transmission line, and the input of the counterclockwise loop transmission line is output to the counterclockwise loop transmission line. As shown in Figure 10, the clockwise loop transmission system and the center node are connected. 1. Remote node 2. Folding back, the center node and the system in which the signal propagates.
Two transmission systems are established.

In the case of FIG. 8, remote node 2 detects frame synchronization in the left transmission system, and remote node 3. remote node 4
The center note detects frame synchronization in the clockwise transmission system, and the center note detects frame synchronization in the left and right transmission systems.
○Similarly to the case shown in the figure, as shown in FIG.
-Remote node 3-Return 1-Remote node 3-Remote node 4-Center node and signal propagation system 2
Two transmission systems are established. In this way, a transmission system is established between the center node and each remote node even in a failure state of the transmission system.

Next, a description will be given of how the center node grasps the state of the transmission system when the transmission system is established. In the present invention, the center node 1 grasps the state of the transmission system based on the loop identifier 1 included in a part of the header of the transmission frame. FIG. 12 shows an example of a frame structure in the present invention. A frame consists of a frame header and data. The frame header consists of a pit sequence for synchronizing the frames circulating in the frame synchronization, a loop identifier, and a loop status display section. The loop identifier and loop status display section consist of 1 byte, and b○ is the loop identifier.

bl and b2 represent a loop state display section, and b7 represents an error check bit. Notes 3 to b6 are undefined. A loop identifier is attached when the center node 1 transmits a transmission frame. Center node 1 sets the loop identifier to "○" (binary number) for frames sent to the clockwise transmission system, and sets the loop identifier to "1" for frames sent to the counterclockwise transmission system.
'' (binary number).Then, the /lz- of the frame received from the center node 1 and 2 left and right transmission paths is sent out.
The state of the loop transmission system is grasped by determining the contents of the print. FIG. 13 shows the loop identifiers received from both the left and right transmission paths and the state of the loop transmission system at that time.

Under normal conditions, frames sent from both the left and right transmission paths return from the sending side. If the right-handed transmission line is in a failure state, two transmission lines are formed as shown in Figure 9, so the loop identifier of each received frame is 1'' (binary number) indicating the left-handed transmission line. Furthermore, if the left-handed transmission system is in a failure state, the two transmission systems shown in FIG. binary number). Furthermore, if the image transmission system is in a failure state, two transmission systems shown in FIG. 11 are formed, so a loop identifier indicating a reverse loop is received. In other words, "1" indicating a counterclockwise transmission channel is received from the clockwise transmission channel, and "0" indicating a clockwise transmission channel is received from the counterclockwise transmission channel.In this way, the state of the loop transmission system can be grasped in detail. can do.

The center node 1, which has grasped the status, displays normal ゛oO゛ (binary number), clockwise transmission line segment loop o1'' (2
Enter the counterclockwise transmission path loop "10" (binary number), loopback "11" (binary number) and notify each remote node.

At this time, since a transmission system is established between the center node and the remote nodes, this fault information can be transmitted with high reliability.

Further, recovery from a failure state can also be performed automatically. For example, it is assumed that the fault location has been repaired in the loopback state shown in FIG. In the loopback state, only one 7-frame aligner of center node 1 is operating (A), so if the 7-frame aligner of the clockwise transmission path is currently operating, even if the fault is restored, the counterclockwise transmission system frame synchronization is not established. In the loopback state, when the center node 1 detects a change in the loop identification state, it forcibly operates the two frame aligners to search for the state of the loop transmission system. As a result, the center node learns that the loop transmission system has been repaired and returns to a normal state. In response to this, each remote node also returns to its normal state, and the loop transmission system automatically returns. FIG. 14 shows an example of the configuration of a state transition diagram of the center node based on the loop identifier described above. The status consists of four states: normal state, clockwise transmission line one loop state, counterclockwise transmission line one loop state, and loop state. The number "O" in parentheses indicates the signal sent from the clockwise transmission line. Loop identifier, number “1” indicating that
is a loop identifier indicating that the signal is sent from the counterclockwise transmission path, and the arrow transitions between each state depending on the μ loop identifier (of the signal received by the center node from the left and right transmission paths). do.

In the normal state, if "○" is detected on the clockwise transmission path and "1pa" is detected on the counterclockwise transmission path, the normal state remains.

Hereinafter, the loop identifier detected from the clockwise transmission path and the loop identifier detected from the counterclockwise transmission path will be referred to as (loop identifier crossed from the clockwise transmission path, loop identifier detected from the left-handed transmission path). When (0, 0) is detected, the state changes to the clockwise transmission line segment loop state, when (1°1) is detected, the state shifts to the clockwise transmission channel segment loop state, and when (1, O) is detected, the state shifts to the loop bank state.

When (0,0) is detected in the clockwise transmission line segment loop state, it remains in that state. When (o, 1) is detected, it changes to the normal state, when (1, 1) is detected, it changes to the clockwise transmission line segment loop state, and when (I IQ) is detected, it changes to the loopback state.

When (1, 1) is detected in the counterclockwise transmission line loop state, that state remains. When (0,1) is detected, the state changes to the normal state, when (0,0) is detected, the state changes to the clockwise transmission line segment loop state, and when (1+ o ) is detected, the state changes to the loop bank state.

In the loopback state, if (1, O) is detected, the loopback state remains. If any other condition is detected, the device returns to normal condition.

We have explained automatic recovery above, but it is also possible to perform it manually by receiving a notification from the center node or remote node.

As described in detail, according to the present invention, the transition to the loop bank and single loop states in the event of a transmission system failure can be performed with high reliability and clarity in any of the above situations.

[Brief explanation of drawings]

Figure 1 is a diagram showing an outline of the loop network, Figure 2 is a diagram showing an example configuration of a transmission control circuit of a remote node, and Figure 3 is a diagram showing an example of the configuration of a transmission control circuit of a remote node.
The figure shows an example of the configuration of the transmission control circuit of the center node, Figure 4 shows the status of the remote node, Figure 6 shows the status of the center node, and Figure 6 shows the clockwise transmission path failure status. 7 is a diagram showing a counterclockwise transmission path failure state, FIG. 8 is a diagram showing a left and right transmission path failure condition, and FIG. 9 is a diagram showing a clockwise transmission path in a loop network control system according to an embodiment of the present invention. Figure 1Q is a diagram showing the propagation of a signal in a fault state;
The figure shows the propagation of the signal in the left and right transmission path failure state.
Figure 2 shows an example of the configuration of the loop identifier and loop status display section, Figure 13 shows an example of the state of the center node, and Figure 14 shows an example of the configuration of a state transition diagram of the center node. It is a diagram. 1...Center node, 2-4...Remote node, 11-15...Terminal, 20...
・Clockwise transmission line input signal level detection circuit, 21...
...Clockwise transmission line decoder, 22...Transmission line switching circuit, 23...Clockwise transmission line receiving circuit, 24...
...CPU, 26...Clockwise transmission line transmission circuit, 26...Clockwise transmission line encoder, 27...
Bypass switch for clockwise rotation, 30... Counterclockwise transmission line input signal level detection circuit, 31... Counterclockwise transmission line decoder, 33... Counterclockwise transmission line receiving circuit. , 35... Counterclockwise transmission line transmission circuit, 36...
...Counterclockwise transmission line encoder, 37...Counterclockwise bypass switch, 4o...Logic processing circuit, 41...
...Clockwise transmission line frame aligner, 42...
...Counterclockwise transmission line frame aligner, 101...
・Clockwise transmission line, 102... Counterclockwise transmission line. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
Fig. 2Q Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 1 O Fig. 11 f Fig. 12

Claims (3)

[Claims] (1) A clockwise signal propagates between a remote node that controls data access to the transmission path and a center node that controls data access to the transmission path and synchronization of the transmission system by circulating frames at a constant cycle. A circular loop transmission path and a counterclockwise loop transmission path in which signals propagate counterclockwise are connected by two loop transmission paths, and various information is connected to remote nodes and center nodes using both loop transmission paths. A loop network is formed for communication of processing devices, and the remote node and the center node rotate clockwise;
It has an input signal level detection circuit and a frame synchronization detection circuit for both counterclockwise loop transmission lines, and when a drop in the input signal level or frame synchronization is detected, the loop transmission line on the detected side is supplied with a signal and normalized. When the input signal level and frame synchronization return to normal, the signal on the loop transmission line is looped back, and when the input signal level and frame synchronization return to normal, the signal looping is stopped. By outputting to the counterclockwise loop transmission line,
A loop network control system characterized by forming a loopback or a single loop in response to a failure in the transmission system. (2) A loopback formed in response to a failure in the transmission system;
2. The loop network control system according to claim 1, wherein a single loop and a normal state are identified by a loop identifier in a frame header portion that distinguishes between clockwise rotation and counterclockwise rotation. (3) A loopback formed in response to a failure in the transmission system;
2. The loop network control system according to claim 1, wherein the identification of the single loop and the normal state is notified to each node of the state of the loop transmission system by means of a loop state display in a frame header.