JP2989091B2 - Data switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data switch applied to a data transmission network which can secure a plurality of transmission paths between communication nodes such as a mesh network and a loop network.

In a data transmission network such as a mesh network or a loop network, communication nodes (for example,
Data is sent between the host computer and the terminal via a plurality of transmission paths, and one of the transmission paths is used as a working transmission path, and when it is recognized that a failure has occurred in the working transmission path, the data is transferred to another backup transmission path. By switching, continuity of communication is ensured. The present invention relates to an improvement of a data switch for switching a transmission path when a failure occurs in a data transmission network employing such a communication system.

[0003]

2. Description of the Related Art FIG. 4 shows an example of a data transmission network (network). In the figure, A, B, C, D, E
Is a transmission device (multiplexing device), and these transmission devices A, B, C, D, and E are transmission lines (lines) L1, L2, L
The transmission device B is connected to a host computer (HOST) 4, and the transmission device A is connected to a plurality of terminals including the terminal 5.
Although not shown, the other transmission devices B, C, D,
E is also connected to a plurality of terminals.

In such a transmission network, for example, when the terminal 5 connected to the transmission apparatus A receives data from the host computer 4, the transmission path between them is as follows:
Transmission path (route 1) via HOST → E → A and H
Transmission path via OST → E → D → C → A (Route 2)
Exists, and data from the host computer 4 is sent to the transmission apparatus A via these two transmission paths.

[0005] The data switch provided in the transmission apparatus A, for example, normally sends data transmitted via the route 1 to the terminal 5 when the route 1 is in use.
Then, the data switch checks the check bits of the data sent via the route 1, and when the error rate (data error rate) exceeds a predetermined value or when an error occurs continuously, etc. , Transmission line (in this case, L
When it is determined that a failure has occurred in 2), the route is switched from the route 1 to the route 2 and the data transmitted via the route 2 is transmitted to the terminal 5.

[0006]

However, in the conventional data switch, when it is determined that a failure has occurred in the transmission line, switching is performed immediately from the viewpoint of shortening the instantaneous interruption time as much as possible. There are the following problems.

In other words, since the number of transmission devices and the length of the transmission path differ between a plurality of transmission paths between communication nodes, the time required for data arrival generally differs. When this occurs, the same data may be transmitted redundantly.

For example, in the transmission apparatus A of FIG. 4, as shown in the time chart of FIG. 5, data from the route 2 (the transmission line L5) is smaller than data from the route 1 (the transmission line L2). If data is received with a delay, and therefore the route 1 is currently used, and if the route 2 is switched to when the data S2 is received from the route 1, the data S2 is redundantly transmitted to the terminal 5. , And the terminal 5 receives the data S2 redundantly.

In a communication protocol (for example, a BSC protocol) that does not allow such redundant reception of data, problems such as disconnection of a session (path) between communication nodes occur. Sometimes.

The present invention has been made in view of the above points, and an object of the present invention is to provide a data transmission network which can secure a plurality of transmission paths between communication nodes such as a mesh network and a loop network. An object of the present invention is to provide a data switch capable of preventing occurrence of a failure due to redundant transmission of data to a node.

[0011]

A data switch according to the present invention for solving the above-mentioned problem is to convert one of a plurality of incoming routes into a single outgoing route in accordance with an input switching signal. A data switching circuit selectively connected to the input path, a signal monitoring circuit for monitoring the occurrence of an error in the data received from the incoming path, and an error signal when the received data from the current incoming path has an error. A determination circuit for transmitting a switching signal to the data switching circuit so as to switch and connect an incoming route other than the incoming route to the outgoing route.

Further, when the same data is transmitted from the working input path triggered by the transmission of the switching signal.
And a timer that counts a designated time set in advance based on the time difference between when the signal is sent from the other input path and a timer that counts up from the transmission of the switching signal to the end of counting the designated time. and a data invalid circuit to disable the received data, the target nodes
This prevents problems caused by duplicate transmission of data to the server .

The data invalidating circuit is provided between the data switching circuit and an outgoing path, or provided between the data switching circuit and a plurality of incoming paths. The designated time set in the timer can be changed. The designated time set in the timer is determined in consideration of the delay difference of the same data from two routes before and after the switching.

In addition, a switch for forcibly selecting an incoming route to be connected to the outgoing route is provided, and when the switch is switched, the determination circuit is configured to receive the signal regardless of the monitoring result by the signal monitoring circuit. A switch signal can be transmitted according to the setting of the switch.

[0015]

According to the present invention, the received data is invalidated from the transmission of the data switching signal by the determination circuit to the end of the counting of the designated time by the timer. Therefore, when the same data as the data received from the route before the change is received from the route after switching, the data received from the route after switching is invalidated and not transmitted to the target node, Even when the route is switched during communication, the node does not receive the same data redundantly, and it is possible to eliminate problems such as disconnection of the session (path) due to this.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of a data switch to which the present invention is applied.
FIG. 3 is a block diagram illustrating a configuration of an example. The data switch 10 is provided, for example, in the transmission device A configuring the network illustrated in FIG. The data switch 10 includes a data switching circuit 11, a route 1 signal monitoring circuit 12, a route 2 signal monitoring circuit 13, and a reception system selection determining circuit 1.
4, timer 15, data invalidation circuit 16, and switch 1
7 is provided.

The data switching circuit 11 changes one of a plurality of incoming routes (route 1 and route 2) to a single outgoing route (route 1 and route 2) in accordance with a switching signal 18 sent from the receiving system selection judging circuit 14. Selectively connect to route 3).

The route 1 signal monitoring circuit 12 and the route 2 signal monitoring circuit 13 are provided corresponding to the route 1 and the route 2, respectively. Monitor the occurrence of Monitoring of the occurrence of an error by each of the signal monitoring circuits 12 and 13 is performed by a data transmission node (for example, FIG.
In step (1), the host computer 4) checks whether the assigned check bit is correct or incorrect, and the monitoring results of the signal monitoring circuits 12 and 13 are sent to the receiving system selection determining circuit 14.

The receiving system selection judging circuit 14 preliminarily determines the number of errors in the received data (the number of errors occurring per a predetermined number of received data or the number of continuous errors) based on the monitoring results of the signal monitoring circuits 12 and 13. If the received data exceeds the predetermined value, it is determined that a failure has occurred in the working route (in this case, route 1) from which the received data has been sent, and the spare route (in this case, Is a route 2) to a departure route (route 3).
To the switching signal 18.

The data switching circuit 11 receives the switching signal 1
8, the connection between the route 1 and the route 3 is changed to the route 2 and the route 3
Switch to connection. The change of the switching signal 18 by the receiving system selection determining circuit 14 is notified to the timer 15.

The timer 15 counts a preset designated time, triggered by a notification from the receiving system selection determining circuit 14 (trigger). In the timer, a required time is specified and set in advance in consideration of a time difference (delay difference) between the case where the same data is sent from the route 1 and the case where the same data is sent from the route 2. The designated time set in the timer 15 can be arbitrarily changed.

The timer 15 continues to send the data invalidation signal 19 to the data invalidation circuit 16 from the notification by the receiving system selection judging circuit 14 to the end of the counting of the designated time.

The data invalidating circuit 16 is provided between the data switching circuit 11 and the outgoing path 3, and while the data invalidating signal 19 from the timer 15 is being sent, via the data switching unit 11. The transmitted data is invalidated, and the transmission to the outgoing route 3 is stopped.

The switch 17 is provided for testing the network and the like. When a maintenance person or the like manually changes the setting, the setting contents are detected by the reception system selection determining circuit 14. When the switch 17 is changed, the receiving system selection judging circuit 14 sends the corresponding switching signal 18 to the data switching circuit 11 irrespective of the monitoring result from each of the signal monitoring circuits 12 and 13.

Next, a description will be given with reference to a time chart shown in FIG. It should be noted that the comparison with the time chart of the prior art shown in FIG. 5 is helpful for understanding.

In FIG. 5, since the data from the route 2 (transmission line L5) is received later than the data from the route 1 (transmission line L2), when the route 1 is in use, When switching to the route 2 when the data S2 was received from the route 1, the data S2 was redundantly transmitted to the terminal 5.

However, according to this embodiment, as shown in FIG.
Is switched to the route 2 at the time when the data S2 is received from the controller, the data invalidation signal 19 is input to the data invalidation circuit 16 at the same time as the switching until the designated time elapses.
Is invalidated by the data invalidating circuit 16 via the data switching circuit 11. Therefore, the data S2 from the route 2 is included in the transmission data to the target node (terminal 5).
Will not be sent.

Therefore, even if a switching operation occurs from a route with a small delay time (route 1) to a route with a large delay time (route 2) during communication, data may be lost but duplicated. Even if a communication protocol (for example, the BSC protocol) that does not allow duplicate reception of data is adopted, a problem such as disconnection of a session (path) between communication nodes does not occur.

When a switching operation occurs from a route having a long delay time (route 2) to a route having a short delay time (route 1), duplication of data does not occur. The designated time set to 15 may be zero.

FIG. 3 is a block diagram showing the configuration of the second embodiment of the present invention. The same components as those of the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and only different portions will be described.

That is, in the first embodiment, the data invalidation circuit 1
6, the data invalidation circuit 16 is provided between the data switching circuit 11 and the outgoing route 3 in this embodiment. Are provided between them. The effects are the same as in the first embodiment.

[0032]

Since the present invention is configured as described above, in a data transmission network in which a plurality of transmission paths can be secured between communication nodes such as a mesh network or a loop network, a failure due to redundant transmission of data to a target node is caused. This provides an effect of providing a data switch in which the occurrence of the data is prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a time chart of the first embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 4 is a diagram illustrating an example of a data transmission network (network).

FIG. 5 is a time chart of the related art.

[Explanation of symbols]

 1, 2 Incoming route 3 Outgoing route 4 Host computer 5 Terminal 10 Data switch 11 Data switching circuit 12 Route 1 signal monitoring circuit 13 Route 2 signal monitoring circuit 14 Receiving system selection judgment circuit 15 Timer 16 Data invalidation circuit 17 Switch 18 Switching signal 19 Data invalid signal

Claims (5)

(57) [Claims] 1. A data switching circuit for selectively connecting one of a plurality of input paths to a single output path in response to an input switching signal, and for generating an error in data received from the input path. A signal monitoring circuit for monitoring, and a switching signal to the data switching circuit so as to switch and connect another input path other than the working input path to the output path when an error occurs in data received from the working input path. And the same data is used in response to transmission of the switching signal .
From the other input path and from the other input path
A timer that counts a designated time set in advance based on a time difference when the data is received, and a data invalidating circuit that invalidates received data from the time when the switching signal is transmitted to the time when the counting of the designated time is completed. ,
Prevents failures caused by duplicate transmission of data to the target node
Data switcher characterized by being stopped . 2. The data switch according to claim 1, wherein the data invalidating circuit is provided between the data switching circuit and an output path. 3. The data switch according to claim 1, wherein the data invalidation circuit is provided between the data switching circuit and the plurality of input routes. 4. The data switch according to claim 1, wherein a designated time set in the timer can be changed. 5. A switch for forcibly selecting the incoming path to be connected to the outgoing path, wherein the determination circuit is configured to switch the switch when the switch is switched, irrespective of a monitoring result by the signal monitoring circuit. 2. The data switch according to claim 1, wherein a switch signal is generated according to the setting of the switch.