JPH0457423A - Data transmission network having clock topology revision function - Google Patents

Abstract

PURPOSE:To attain quick restoration of synchronization of a monitored equipment unable to receive a reference clock by revising a clock topology automatically. CONSTITUTION:After the receipt of a signal representing reference clock interruption from a monitored equipment 23, a monitor 20 retrieves a transmission line 33 having no reference clock and a monitor 23 in a slave mode in monitored equipments 22, 23 connecting to the transmission line by using a data table 3, retrieves all transmission lines 31, 33 connecting to the monitored equipment 23 in the slave mode by using the data table 3 so as to discriminate the relation between the relative master mode and slave mode between the monitored equipments 23, 22 connecting to both ends of the transmission line 31 through which the reference clock is normally sent. When the monitored equipment 23 unable to receive the reference clock is set to the master mode, a clock topology processing section 2 revises the clock topology.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a data transmission network that can recover from a loss of the reference clock in a transmission network synchronized by a reference clock, and a method for changing the clock topology for that purpose. The purpose is to quickly restore the synchronization of the monitored device by automatically changing the clock topology.
A clock-related failure is recognized by an alarm that indicates reference clock disconnection, a route for transmitting the clock again to the monitored device is selected using a data table containing information regarding clock topology, and the monitored device on the route is selected. The present invention is characterized in that it includes a clock topology search unit that determines the clock transmission/reception mode of the monitored device, and a clock topology processing unit that reverses the clock transmission/reception modes of the monitored device and the monitored device facing the monitored device.

[Field of Industrial Application] The present invention relates to a data transmission network that can recover from reference clock interruption in a transmission network synchronized by a reference clock, and a clock topology changing method therefor.

In a transmission network having a plurality of devices that transmit and receive multiplexed data, it is necessary to synchronize the devices in order to exchange data correctly with each other. At that time, any one of the monitored devices equipped with an oscillation device for generating a clock is designated as a clock master that generates a reference clock, and the reference clock is transmitted to all devices in the network to control the network. Synchronize.

Various routes and directions can be taken to supply this reference clock to each device in the network. What defines the route and direction for supplying the reference clock to the entire network is called a clock topology.

Here, between two devices connected by a certain number of transmission paths, there is a device that relatively transmits the reference clock and a device that receives the reference clock. In this case, a device that relatively transmits the reference clock is called a master mode device, and a device that relatively receives the reference clock is called a slave mote device.

In such a network, if the reference clock is interrupted, the device loses synchronization with other devices in the footwork. An example of this is disconnection of the reference clock due to the occurrence of a transmission path failure.

Therefore, even in such a case, there is a need for a clock topology changing method that can quickly resume correct data exchange.

[Prior Art] FIG. 9 shows a conventional configuration diagram. In the figure, 40 is a monitoring device, 41, 42, 43, and 44 are monitored devices, of which 41 is a clock master.

30.51, 52, 53, 54.55 are transmission lines for transmitting the reference clock, and of these, 51, 52.53 drawn by solid lines are actually used for transmitting the reference clock at this point. transmission line, 5 drawn by a dotted line.
4.55 is a backup reference clock transmission transmission line.

The monitoring device 40 receives status information from each of the monitored devices and issues various commands to each of the monitored devices.

In FIG. 9, the direction of the arrow indicates the direction in which the reference clock is transmitted, with the starting point of the arrow being the master mote' device and the ending point being the slew mode device.

Here, it is assumed that a failure has occurred in the transmission line 52.

Of course, what will be described below can also be applied to cases where the reference clock is interrupted due to other factors.

Conventionally, the monitored device 42 detects the interruption of the reference clock due to a failure in the transmission line 52, and issues an alarm to the monitoring device 40 to notify it. The monitoring device 40 displays the occurrence of an abnormality on the display section 17 by receiving the alarm in the alarm extraction section 4 included in the device.

However, there was no way to identify the transmission path where the failure occurred, and it was not possible to change the clock topology. Therefore, the transmission line 52 is bypassed and the monitored device 4
It is not possible to send the reference clock to 2,
In order to synchronize the monitored device 42, it was necessary to recover from a fault in the transmission line 52 or to go to the device and manually change the clock topology.

Problems to be Solved by the Invention Therefore, the monitored device 42 that is no longer able to receive the reference clock is isolated from the network for a long time, and cannot obtain timing information, making it difficult to accurately transmit data. It was hindering my ability to do so.

In this case, by having means for automatically changing the clock topology, the monitored device can be restored without taking a long time.

An object of the present invention is to quickly restore the synchronization of a monitored device that has become unable to receive a reference clock by automatically changing the clock topology.

[Means for Solving the Problems] FIG. 1A is a diagram explaining the principle of a monitoring device 20 according to the present invention. In FIG. 1A, 1 is a clock topology search unit, 2 is a clock topology processing unit, 3 is a data table containing information regarding the clock topology, and 4 is an alarm that receives an alarm from a monitored device and generates an column regarding the reference clock. This is an alarm extraction unit that extracts alarms.

The monitoring device 20 is provided with a clock topology search unit 1 that detects the occurrence of a failure in the reference clock, and a clock topology processing unit 2 that changes the clock topology.

FIG. 1B is a diagram explaining the principle of the network in the present invention.

The explanation will be given below using FIGS. 1A and 1B.

In the monitoring device 20, after receiving a signal from the monitored device 23 that indicates the disconnection of the reference clock, the monitoring device 20 detects the transmission path 23 where the reference clock is no longer transmitted and the monitored devices 21 and 23 connected to the transmission path 33. Among them, the device 23 in slave mode is searched using the pig table 3.

Next, all the transmission lines 31 and 33 connected to the slave mode device 23 are searched using the data table 3, and among them, the transmission line 31 that can normally transmit the reference clock is recognized.

Furthermore, regarding the recognized transmission line 31, the relative relationship between the master mode and slave mode between the monitored devices 23 and 22 connected to both ends thereof is determined.

If the monitored device 23 becomes unable to receive the reference clock,
is in master mode with respect to the opposing monitored device 22, the clock topology is changed in the clock topology processing section 2.

The data table 3 includes a first table containing information regarding the relative master mode and slave mode relationship between two monitored devices connected to each transmission path, and a a second table containing information regarding whether the device is a clock master device or a slave mode device, and information regarding the transmission path used by each slave mode device to receive the reference clock; A third table contains information regarding whether the current status of the monitored device is normal or abnormal, and information about which transmission path is connected to each monitored device. and has a fourth table.

"Function" When the reference clock is cut off, an alarm reporting this is emitted from the monitored device 23.The transmitted alarm is extracted by the alarm extraction section 4 in the monitoring device 20.If the alarm is related to the reference clock, If so, the transmission line 33 where the reference clock transmission has stopped
, and among the monitored devices connected to the transmission line 33, the device 23 in slave mode is searched.

Thereby, the transmission line 33 used by the slave mode device 23 to receive the reference clock can be recognized.

Next, the transmission line 3 connected to the monitored device 23
3.31, and identify the transmission line 31 that can normally transmit the reference clock.

At this time, in the transmission path 31, what is the relative state of the relationship between the master mode and the slave mode between the monitored device 23 that has become unable to receive the reference clock and the monitored device 22 that opposes it? Determine whether it is present.

The processes up to this point are performed in the clock topology search section 1.

If the monitored device 23 is in master mode, it cannot receive the reference clock. Therefore, a command is issued to both wave monitoring devices 22 and 23 to reverse the relationship between master mode and slave mode.

This process is performed in the clock topology processing section 2.

The operations described above, such as search, recognition, identification, and discrimination, are all performed using the data table 3.

Through the above-described operation, it is possible to change the clock topology and supply the reference clock again to the monitored device 23 which has been unable to receive the reference clock.

Embodiment 1 FIG. 2 shows a configuration diagram of a monitoring device 20 in an embodiment. In FIG. 2, 1 is a clock topology search section, 2 is a clock topology processing section, 3 is a data table, 4 is an alarm extraction section, 5 is a reception section, and 6 is a transmission section.

The data table 3 contains information regarding the clock topology in this network.

FIG. 3 shows a configuration diagram of a monitored device in one embodiment. In FIG. 3, 7 is a monitoring control section, and 8 is a transmission line interface section. In the monitoring control section 7,
9 is a command receiving section, and 1° is a command issuing section. In the transmission line interface section 8, 11 is a command receiving section 1, 12 is a clock topology changing section, 13 is a clock abnormality determining section, 14 is an alarm generating section, 15 is a transmitting/receiving section, and 16 is a data table.

FIGS. 4A and 4B show the configuration of a network in one embodiment. Of these, FIG. 4A shows the network when a transmission path failure occurs, and FIG. 4B shows the network in a state where the synchronization of the monitored device 23 has been restored. In Fig. 4, 20 is a monitoring device, 21, 22, 23, 24.2
5 is a monitored device. Of these, 21 are clock masters.

The transmission line 30 is a transmission line connecting the monitoring device 20 and the monitored device 21, solid line arrows 31, 32, 33.34 are current clock transmission lines, and dotted line arrows 35, 36, 3.
7.38 indicates a spare clock transmission line. Note that the arrow indicates the direction in which the reference clock is transmitted, and does not mean the direction in which data is transmitted. It is also possible to transmit data using a transmission line different from the line through which the reference clock is transmitted.

In this network, status signals from the monitored device and commands from the monitoring device 20 are exchanged through the transmission path 30 and the pig transmission path.

5A, B, C, and D show the inside of the data table 3 in the monitoring device 20. FIG. 5A shows a clock mode table, FIG. 5B shows a current clock topology table, FIG. 5C shows a transmission path current state table, and the fifth diagram shows a monitored device connection table.

To explain each data table, the Cronk Mort Cheeple shown in FIG. 5A stores information regarding the relative relationship between master mode and slave mode between two monitored devices connected to each transmission line.

Figure 5B Current Clock Topology Table provides information regarding which monitored devices are clock master devices or slave mode devices, and information regarding the transmission path used by each slave mode device to receive the reference clock. It contains.

The transmission path current table shown in FIG. 5C stores information regarding whether the current state of the transmission path is normal or abnormal.

The fifth monitored device connection table stores information on which transmission path is connected to each monitored device.

FIG. 6 is a flowchart of processing within the monitoring device 20, FIG. 7 is a flowchart of processing within the transmission line interface unit 8 when the reference clock is disconnected, and FIGS. 8A and 8B are when the clock topology is changed within the monitored device. It is a processing flowchart.

The explanation will be given below using the figures listed above.

Now, consider a case where a failure occurs in the transmission line 33, as shown in FIG. 4A.

When a transmission path failure occurs and the reference clock transmitted through the transmission path 33 is cut off, the clock abnormality determination unit 13 in the monitored device 23 is detected by the procedure shown in the flowchart of FIG.
works. That is, when the reference clock is disconnected, the clock abnormality determination section 13 detects the transmission line interface section 8.
It is determined whether or not the reference clock is being pulled in (SL in FIG. 7). If the reference clock is not being pulled in, it is determined whether there is another transmission line ink face part that is pulling in the reference clock (Fig. 7, S2).
.

If there is no transmission line ink face unit that pulls in the reference clock, the transmission line interface unit 8
The content of the data table 16 in
．． S4). Next, it is determined whether the reference clock is being pulled in normally (S5 in FIG. 7).

If the reference clock is not pulled in normally, the clock abnormality determining section 13 determines that a failure has occurred, and an alarm is issued to the monitoring device 2o (FIG. 7, S6 and S7).

The monitoring device 20 receives the alarm at the receiving section 5, and extracts the alarm related to the reference clock at the alarm extracting section 4 (Sl in FIG. 6).

Next, the clock topology search unit 1 searches for a transmission path where it is no longer possible to transmit the reference clock. The extracted alarm is the monitored device 23 that was receiving the reference clock.
Therefore, in this case, using the current clock topology table in FIG. 5B, the monitored device 2
3 determines that a failure in transmitting the reference clock has occurred on the transmission line 33 that was used to receive the reference clock (S2 in FIG. 6). Although this does not immediately mean that a transmission line failure has occurred, it is sufficient to determine that it is no longer possible to transmit the reference clock using the transmission line 33.

Next, referring to the clock mode table in Figure 5A,
It is searched that the slave mode device on the transmission path 33 is the monitored device 23 (FIG. 6, S3). By performing this search, it is possible to confirm that the monitored device 23 has received the reference clock using the transmission path 33.

Next, with reference to the fifth monitored device connection table, it is determined whether the transmission path connected to the monitored device 23 is the transmission path 33,
36.38 (Fig. 6, S4), search the transmission line current state table in Fig. 5 C for each transmission line, and recognize that the transmission line 36°38 is normal (Fig. 6, S4). S5).

Here, referring again to the clock mode table in FIG. 5A, it is recognized that the monitored device 23 is relatively in the master mode on the transmission lines 36 and 38 (see FIG. 6).
36). As a result, the monitoring device 20 determines that the monitored device 23 is unable to receive the reference clock.

In this case, the clock topology processing unit 2 refers to the clock mode table A in FIG.
recognizes that the monitored devices 24, 25 respectively connected to the monitored device 23 are in slave mode with respect to the monitored device 23;
Select any one. The clock topology processing section 2 issues a command from the transmitting section 6 to change the monitored bag W23 connected to the transmission line 38 to the slave mode and the monitored device 25 facing it to the mask mode (see FIG. 6). S7).

If the monitored device 23 is in slave mode on any of the transmission lines 36, 38, then
The following clock topology change process is not performed (FIG. 6, S9).

On the other hand, the monitoring control section 7 in the monitored devices 23 and 25 receives the command from the monitoring device 20 and performs the process shown in FIG. 8A. The processing in the monitored device 23 will be described below.

Upon receiving the command transmitted from the monitoring device 20, the command receiving section 9 determines whether or not there is a transmission line interface section 8 that is the target of receiving the command (
Figure 8 A-31).

If there is a transmission line interface section 8 that is the target of command reception, the command issuing section 10 issues a command to change the clock topology to the corresponding transmission line interface section 8 (Fig. 8 A-3).
2).

Then, in the transmission path interface section 8,
processing is performed. The command receiving section 11 in the transmission line interface section 8 receives the command (FIG. 8B-33). If the command is related to changing the clock topology, the clock topology changing unit 12 changes the transmitting/receiving unit 15 from master mode to slave mode (FIG. 8B-34.S5).

Finally, the contents of the data table 16 containing information regarding the clock topology of the monitored device 23 are updated, and the clock topology changing process is completed (FIG. 8B-36). Similar processing is performed in the monitored device 25, and the transmission line 38 is changed from slave mode to mask mode.

After changing the clock topology according to the above procedure, the clock topology processing section 2 writes information on the current clock topology to the data table 3 to update the contents (FIG. 6, 38).

As a result, as shown in FIG. 2B, the monitored device 23
can now receive the reference clock through the transmission line 38, synchronize with the network, and enable normal data transmission.

(Other Examples) In this example, it is assumed that the reference clock disconnection is due to a transmission path failure, but even if the reference clock disconnection is due to a failure in the monitored device, the reference clock disconnection can be detected by the same means. It becomes possible to restore the synchronization of the monitored device.

In this embodiment, the reference clock is sent to each device separately from the data, but even if the data string includes timing information for synchronization, the clock topology can be changed in the same way. .

Furthermore, in this embodiment, commands from the monitoring device and status signals from each monitored device are transmitted and received through a transmission path for transmitting data, but the commands and status signals are transmitted between the monitoring device and each monitored device. The clock topology can be changed in the same way even when data is transmitted and received via a dedicated line that directly connects the clock.

[Effects of the Invention] As explained above, by implementing the present invention, it is possible to automatically and quickly restore the synchronization of a device whose reference clock has been cut off, and to perform normal data transmission. It becomes like this.

[Brief explanation of the drawing]

FIG. 1A is a diagram explaining the principle of the monitoring device 20 in the present invention, FIG. 1B is a diagram explaining the principle of the network in the present invention, FIG. 2 is a configuration diagram of the monitoring device 20 in one embodiment, and FIG.
The figure is a configuration diagram of a monitored device in one embodiment, FIG. 4A is a configuration diagram of a network when a transmission path failure occurs in one embodiment, and FIG. 4B is a synchronization recovery of the monitored device 23 in one embodiment. Figure 5A is a clock mode table, Figure 5B is a current clock topology table, and Figure 5B is a current clock topology table.
FIG. C is a transmission path current state table, the fifth diagram is a monitored device connection table, FIG. 6 is a flowchart of processing within the monitoring device 20, and FIG. FIG. 8A is a process flowchart when clock topology is changed within the supervisory control unit 7, FIG. 8B is a process flowchart when clock topology is changed within transmission line interface unit 8, and FIG. 9 is a diagram showing the configuration of a network according to the prior art. , is. In the principle diagram, 1 is a clock topology search unit, 2 is a clock topology processing unit, 3 is a data table, 4 is an alarm extraction unit, 20 is a monitoring device, 21, 22, 23 are monitored devices, and 30 is a monitoring device 20. A transmission line connecting the monitored device 21, 32 and 33 a transmission line through which a clock is transmitted, and 31 a backup transmission line. Phrase of the present invention 1 Comparison of location of leakage and wealth diagram 1 Figure A Network 0 original farm destination 1 draw y Figure 1 hit □ 2 Te! , Sunari com is 5□71 firing monitoring fold'fL20
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Claims (1)

[Claims] 1) A plurality of monitored devices (21, 22, 23) interconnected by transmission paths (31, 32, 33), and one of the monitored devices (21, 22, 23). connected to at least one of the monitored devices (21,
22, 23), one of the monitored devices (21, 22, 23) is a clock master (21) that generates a reference clock, and the other monitored devices are In a network that is synchronized with the reference clock, the monitoring device (20) recognizes a clock-related failure by an alarm from the monitored device (23) that indicates disconnection of the reference clock, and transmits data containing information regarding the clock topology. Table (3)
a clock topology search unit (1) that selects a route for transmitting the clock again to the monitored device (23) using A monitored device (23) and a monitored device facing it (23)
22) A data transmission network comprising: a clock topology processing unit (2) that reverses the clock transmission/reception mode of the data transmission network. 2) The data table (3) includes a first table containing information regarding the relative relationship between master mode and slave mode between two monitored devices connected to each transmission path; a second table containing information regarding whether the monitored device is a clock master device or a slave mode device and information regarding the transmission path used by each slave mode device to receive the reference clock; A third table contains information on whether the current state of the transmission path is normal or abnormal, and information on which transmission path is connected to each monitored device. Data transmission network according to claim 1, characterized in that it has a fourth table stored therein. 3) A plurality of monitored devices (21, 22, 23) interconnected by transmission paths (31, 32, 33), and at least one of the monitored devices (21, 22, 23) and the transmission path ( 30), and the monitored device (21,
22, 23), one of the monitored devices (21, 22, 23) is a clock master (21) that generates a reference clock, and the other monitored devices are A first step of detecting an alarm indicating disconnection of the reference clock from the monitored device (23) in a network synchronized with the reference clock; and a transmission path (33) in which the reference clock is no longer transmitted due to the alarm. a second step of searching for the monitored device (23) in slave mode among the monitored devices (21, 23) connected to the transmission path (33); ) to search all transmission paths (31, 33) connected to the transmission path (31, 33), and transmission in which the reference clock can be transmitted normally among the transmission paths (31, 33) searched by the third step. Regarding the fourth process of recognizing the channel (31) and the transmission channel (31) recognized by the fourth process,
a fifth step of determining the relative relationship between master mode and slave mode existing between the slave mode monitored device (23) and the monitored device (22) opposite thereto; The slave mode monitored device (23
) is determined to be in master mode relative to the monitored device (22) facing it, a sixth step of reversing the relationship between master mode and slave mode. , How to change clock topology.