JP4014714B2 - Ring system connection switching circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a connection switching circuit of a ring system, and more particularly to a connection switching circuit used in a BLSR (Bi-directional Line Switched Ring) ring system of an optical transmission network using SDH (Synchronized Digital Hierarchy).
[0002]
[Prior art]
Conventionally, many ring-type optical transmission networks have been used as large-scale networks. Various devices have been devised for interconnecting ring-type transmission networks.
For example, the following UPSR (Uni-Directional Path Switched Ring) ring systems have been used.
[0003]
FIG. 9 is an explanatory diagram of a schematic configuration of a conventional UPSR ring system.
In the figure, the ring system is composed of two UPSR rings A and B, and a node A-1 on the UPSR ring A and a node B-1 on the UPSR ring B are connected to each other between the rings of the two UPSR rings A and B. The connection is made.
Each UPSR ring A, B is composed of lines (LA1, LB1) through which data flows clockwise and lines (LA2, LB2) through which data flows counterclockwise.
A plurality of nodes (A-1, A-2, B-1, B-2, etc.) are arranged on each UPSR ring.
[0004]
Nodes A-1 and B-1 that perform interconnection between rings are provided with a PSW (Path Switch), and the two lines are appropriately switched according to the state of the line quality to perform interconnection between the rings. Other nodes that do not directly contribute to the interconnection are also provided with PSW.
In the conventional UPSR ring system, in order to ensure reliability, the same data is always passed through the clockwise line (LA1, LB1) and the counterclockwise line (LA2, LB2).
[0005]
Consider a case where communication is being performed between the node A-3 on the UPSR ring A and the node B-3 on the UPSR ring.
First, the data transmitted from the node A-3 is transmitted on both the clockwise and counterclockwise lines (LA1, LA2) of the UPSR ring A and is input to the node A-1.
[0006]
Two pieces of the same data input to the node A-1 are selected by the PSW1 and the PSW2 and output to the node B-1 on the UPSR ring B. Here, two nodes PSW1 and PSW2 are provided in one node A-1, because, for data transmission from the UPSR ring A to the UPSR ring B, inter-ring connection is performed by two lines L3 and L4. It is.
That is, the data selected by PSW1 is output to node B-1 through line L3, and the data selected by PSW2 is output to node B-1 through line L4.
[0007]
Next, the data input to the node B-1 from the lines L3 and L4 is given to both the selectors S3 and S4. In the selectors S3 and S4, either the data from the line L3 or the data from the line L4 is displayed. Is selected.
Then, the data selected by the selector units S3 and S4 is output on the clockwise (LB1) and counterclockwise lines (LB2) of the UPSR ring B, and both are transferred to the node B-3. In the node B-3, either one of the data is adopted in the internal PSW.
[0008]
In each PSW, the line quality is always checked based on a predetermined standard, and the data with no alarm is selected from the two input data. Conversely, the same operation is performed when data is transmitted from the node B-3 to the node A-3.
[0009]
[Problems to be solved by the invention]
In the UPSR ring system as described above, since the same data flows through the two lines LA1 and LA2, the reliability of data transfer is sufficiently ensured, but the use efficiency of the line is poor. In addition, when a failure occurs in one of the lines, communication is ensured by selecting data sent to the other line, but at this time, the line in which the failure has occurred is not used.
[0010]
The present invention has been made in view of the above circumstances, and provides a connection switching circuit for a ring system that enables more efficient line use when interconnecting a plurality of rings. Is.
[0011]
[Means for Solving the Problems]
  The present invention includes a first ring including a first node and a second node, and a second ring including a third node and a fourth node.
  It has two communication lines that flow data in different directions, and
  In a ring system connected by a working path connecting the first node and the third node and a backup path connecting the second node and the fourth node,
  A connection switching circuit located in each of the nodes,
Using an alarm of data flowing through the two communication lines, an alarm reading unit that generates a control signal for turning back the communication line in the same ring when a line failure occurs in the same ring;
  An alarm monitoring unit that detects an alarm generated in the working path and the backup path and outputs respective alarm detection signals;
  A current / preliminary alarm recognition unit for identifying whether the detected alarm has occurred on the working path or on the backup path using the alarm detection signal, and outputting an identification signal;
  A switching control signal generation unit that generates a control signal for selecting a path used for data transmission between the rings based on the identification signal;,
  Generated by the switching control signal generation unit such that the plurality of data to be chained flowing between the first and second rings is data transmitted from either the working path or the backup path; A concatenation control unit that replaces a control signal related to the first data with a control signal related to other data following the first data;Consisting of
  A ring system that monitors an alarm of data flowing on a working path and a backup path, and selects either the working path or the backup path to perform interconnection between the first ring and the second ring. A connection switching circuit is provided.
  Hereinafter, the concatenation control unit is also referred to as a concatenation control unit.
[0012]
The present invention also provides a BLSR ring system in which the connection switching circuit is provided in each node on a plurality of rings constituting the SDH interface network, and the rings are interconnected by the connection switching circuit. Is.
[0014]
A test control unit that forcibly forms an alarm generation state regardless of whether or not an actual alarm is generated in the working path and the backup path, and provides a pseudo identification signal to the switching control signal generation unit; Also good.
Furthermore, the switching control signal generation unit may include a switching back unit that switches back to the working path based on a forced switching back control signal given from the outside.
The alarm monitoring unit may include a rewritable storage circuit that stores information indicating a duration of an alarm.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below based on the embodiments shown in the drawings. However, this does not limit the present invention.
FIG. 1 shows a schematic configuration diagram of an embodiment of a ring system of the present invention.
In this embodiment, two rings A and B are interconnected by nodes A1, A2, B1, and B2. In the following, an embodiment in which the present invention is applied to a BLSR ring system will be described.
[0016]
In general, one ring is composed of two ring lines. In the UPSR system, the same data is transferred to two ring lines having different directions. For example, a clockwise ring line is a working line and a counterclockwise ring line. Is used as a protection line.
On the other hand, in the BLSR ring system, data is transferred only to the ring line used as the working line. For example, for data in which a clockwise ring line is used as a working line, a counterclockwise ring line is used as a protection line, and for data in which a counterclockwise ring line is used as a working line, The ring line is used as a protection line.
[0017]
In the BLSR ring system, one of the ring lines (for example, LA1 in FIG. 1) is used as a working line and the other ring line (LA2) is used as a communication line between other nodes in order to flow certain data. Is done.
[0018]
In FIG. 1, a node A1 and a node B1 are connected by a route 11 and a route 13, and a node A2 and a node B2 are connected by a route 18 and a route 19.
Each of the rings A and B is composed of two ring lines (LA1, LA2) and (LB1, LB2). The nodes A1, A2, B1, and B2 related to the ring interconnection are provided with a service selector unit (SS) that functions as a connection switching circuit.
[0019]
The service selector unit 1 shown in FIG. 1 is provided in the node A1, and operates to select one of the two data provided from the paths 11 and 12 for each channel and send it to the path 15. Similarly, the service selector unit 2 provided in the node B1 operates to select one of the two data provided from the paths 13 and 14 for each channel and send it to the path 16. One data is composed of a plurality of channels, and the route selected for each channel may be different.
[0020]
For example, the data transferred through the path 17 is branched in the node, and the same data is sent to the path 13 and the path 18 and is given to the service selector unit 2 of the node B1. In the service selector unit 2, either one of the data passing through the route 13 and the data passing through the route 18 is selected and transmitted to the route 16.
[0021]
The service selectors 1 and 2 also have a function of constantly monitoring data provided from two routes (routes 11 and 12 or routes 13 and 14) and checking the line quality of each. Then, the service selector section selects data given from the route with the better line quality. The quality of the line quality is determined by alarm information described later.
[0022]
Thus, since the same data is transferred through the path 13 and the path 18, for example, even if a failure occurs in the path 18, the inter-ring transfer of data is rescued by the path 13. Conversely, even if a failure occurs in the route 11 and the route 13, they are remedied by the routes 18 and 19.
[0023]
FIG. 2 shows a schematic configuration diagram of the inside of the node in the ring system of the present invention. Here, the node A1 shown in FIG. 1 will be described as an example, but the other nodes A2, B1, and B2 have the same configuration.
In FIG. 2, O / E units 31 and 32 are circuits that convert optical signals input from paths 17 and 12 connected to the node A1 into electrical signals, and E / O units 33 and 34 are nodes A1. It is a circuit that converts the electrical signal processed in the optical signal into an optical signal.
[0024]
The DMUX units 37 and 38 are circuits that separate data converted into electrical signals by the O / E unit in units of frames, and the MUX units 35 and 36 are circuits that multiplex some of the data in units of frames. . The selectors 41 and 42 are the main parts that realize the connection switching operation that characterizes the present invention.
That is, the service selector unit 1 in FIG. 1 corresponds to the select unit 41 in FIG. Note that the service selector unit (SS) corresponding to the selection unit 42 in FIG. 2 is omitted in FIG.
[0025]
Data from the path 11 in FIG. 1 is input to the selection unit 41. 1 is input to the selection unit 41 via the O / E unit 32, the DMUX unit 38, and the selection unit 44.
The selection unit 41 compares the alarm information included in the two input data, selects one of them, and transfers it to the selection unit 39. Thereafter, the data output from the selection unit 39 is output to the path 15 in FIG. 1 via the MUX unit 35 and the E / O unit 33.
[0026]
The selection unit 42 also has the same function as the selection unit 41, but is for selecting one of the data from the route 11 and the route 17 and outputting it to the route 20. Which of the two data should be selected is determined by checking the channel quality of both paths. Specifically, alarm information is used.
This alarm information is data used to check the quality of the route through which the data has flowed. This alarm information will be described later.
[0027]
The selectors 39 and 40 in FIG. 2 also have a selector function for selecting and outputting one of the two input data, but mainly for switching connections when a line failure occurs in the ring A. . When a line failure has not occurred, the data provided from the selection unit 41 is selected by the selection unit 39 and sent to the MUX unit 35.
[0028]
When data from the path 11 connected to the ring B is selected in the selection unit 41, the data on the ring B passes through the selection unit 41, the selection unit 39, the MUX unit 35, and the E / O unit 33. And sent to the path 15 on the ring A.
On the other hand, if a failure occurs in the route 12 and the route 20 in the ring A in FIG. 1, the data from the ring B via the route 19 and the route 12 is not input to the service selector (SS) 1.
[0029]
At this time, the occurrence of a failure in the route 12 and the route 20 can be detected by the O / E unit 32 and the DMUX unit 38 which are the pre-input parts, but when the occurrence of this failure is detected, the selection unit 39 Switches the connection as follows.
That is, data given from the path 11 is input to the selection unit 39 via the selection unit 42. Alternatively, the data input from the path 17 to the node A 1 is returned via the O / E unit 31, DMUX unit 37, select unit 43, and select unit 42 and input to the select unit 39.
[0030]
Then, in the selection unit 39, the data that has passed through the selection unit 42 is selected and output from the MUX unit 35 and the E / O unit 33 to the path 15. Similarly, when a failure occurs in the routes 15 and 17, the selection unit 40 selects the data input from the route 12 and passed through the selection unit 41, and sets the MUX unit 36 and the E / O unit 34. It performs the function of returning to the route 20 via the route.
[0031]
Similarly to the selectors 39 and 40, the selectors 43 and 44 are for switching connections when a line failure occurs. When no failure has occurred in the path 12, the data provided from the path 12 as described above is provided to the selection unit 41 via the O / E unit 32, the DMUX unit 38, and the selection unit 44.
[0032]
On the other hand, when a failure occurs in the path 12, it is detected by the DMUX unit or the like that there is no data input from the path 12, so the selection unit 44 selects the data provided from the DMUX unit 37. Switch the connection to.
That is, when a failure occurs in the path 12, the data provided from the path 17 includes the O / E unit 31, the DMUX unit 37, the select unit 44, the select unit 41, the select unit 39, the MUX 35, and the E / O unit. It is sent to the route 15 via 33.
[0033]
The selection unit 43 is normally connected so that data from the DMUX 37 is provided to the selection unit 42. However, when a failure occurs in the route 17, the data provided from the route 12 is provided to the selection unit 42. It is for line connection. Further, the selection unit 45 is for outputting one of the data provided from the route 12 and the route 17 to the route 13.
[0034]
FIG. 1 shows a case where data given from the route 17 is sent to the route 13.
Which data should be selected also in the selector 45 depends on the result of the line quality check.
The above is the outline of the operation of the node contributing to the interconnection between the rings.
[0035]
Next, the data flow of the ring system when a failure occurs in the paths 12 and 20 of the ring A will be described in comparison with the case where there is no failure.
FIG. 1 shows a data flow path when a node A4 in the ring A and a node B5 in the ring B communicate with each other when no failure has occurred.
FIG. 3 is an explanatory diagram of a relief route when a failure occurs in the routes 12 and 20 in the ring system of the present invention.
[0036]
First, in FIG. 1, data transmitted from the node A4 on the ring A to the ring line LA1 is sent to the node A1 through the node A5. The data sent to the node A1 is sent to the node B1 on the ring B through two paths.
One route is a route directly sent from the node A1 to the node B1 through the route 13. The other route is a route from the node A1 to the node B1 via the node A2, the route 18, and the node B2. Data sent through these two paths is input to the service selector 2 of the node B1. In the service selector 2, one of the data is selected in consideration of the channel quality of both paths, and the selected data is sent to the path 16 and given to the node B5.
[0037]
Conversely, when data is transferred from the node B5 to the node A4, the data is transferred from the node B1 directly to the node A1 via the path 11, and from the node B1 to the node B2, the path 19, and the node A2. The data is transferred through two routes of the route transferred to the node A1. In the node A1, either one of the two data from the two routes is selected, sent out on the line LA2, and given to the node A4 via the node A5.
[0038]
In this way, ring A and ring B are two routes, a route (routes 11 and 13) connecting node A1 and node B1, and a route (routes 18 and 19) connecting node A2 and node B2. Therefore, the connection between the rings can be relieved even if a failure occurs in either one of the two paths.
[0039]
In addition, as shown in FIG. 3, when a failure occurs in a route on the ring, avoiding the route in which the failure has occurred, data is returned on another ring line and transmitted to secure a rescue route.
For example, when data transmitted from the node B5 on the ring B to the ring line LB2 is input to the node B1, it is transmitted to the node A1 via the one path 11. The other is sent to node B2 and sent to node A2 via path 19.
[0040]
In FIG. 3, when a failure has occurred in the paths 12 and 20, the nodes A1 and A2 can detect that data passing through the paths 12 and 20 has not been received, so that an operation of turning back the data is performed. That is, the node A1 performs an operation of returning data from the ring line LA1 to LA2, and the node A2 performs an operation of returning data from the ring line LA2 to LA1.
[0041]
Therefore, the data sent to the node A2 is returned to the ring line LA1, passes through the nodes A3, A4, A5, is input to the node A1, is further returned to the ring line LA2, and is input to the service selector 1. .
The service selector 1 of the node A1 compares the data looped back to the ring line LA2 with the data transferred via the path 11 and sends one of the data onto the path 15. Then, the data sent on the route 15 is sent to the node A4 via the node A5.
[0042]
In this way, even if a failure occurs on the line on the ring, the data is looped back and the spare ring line is used, so it is possible to secure two paths in the connection between rings, and to improve the efficiency of use of the ring line. Improvements can be made.
[0043]
Next, the internal configuration and processing of the service selector (SS) that plays an important role in realizing the inter-ring connection function of the present invention will be described.
FIG. 4 shows a configuration block diagram of an embodiment of the service selector (SS).
The service selector (SS) shown in FIG. 4 is the service selector 1 provided in the node A1 on the ring A in FIG. 1, and the route 11 contributing to the connection with the route 12, the route 17 and the ring B is connected. Is done.
[0044]
The service selector 1 is mainly composed of six function blocks (101 to 106) as shown in the figure, but is also provided with so-called microcomputer function blocks such as CPU, ROM, RAM, and timer, which are not shown. Each functional block of the service selector 1 is controlled by the CPU based on a program stored in the ROM or RAM.
[0045]
Data transmitted and received between the nodes through the ring line is configured in an SDH frame format compliant with CCITT.
The following alarm information is stored at a predetermined position in the SDH frame format. For example, LOP (Loss Of Pointer), PAIS (Path Alarm Indication Signal), SLM (Signal Label Missmatch), B3-MAJ (B3-Parity Major Alarm), B3-MIN (B3-Parity Minor Alarm), and the like. Priorities are given to these alarm information, and generally, LOP has the highest priority and B3-MIN has the lowest priority.
By monitoring these alarm information, the quality of the line through which the frame data has been transmitted can be determined.
[0046]
The data input to the node A1 from the route 12, the route 17, and the route 11 is checked for alarm information at a predetermined position in the frame format of the data. For example, a route in which an LOP alarm is detected is determined to have poorer line quality than a route in which an SLM alarm is detected.
[0047]
If none of these alarm information has occurred, it is determined that the quality of the route is good, and the data passing through the route is selected. If alarm information has occurred, the quality of the route is judged to be poor, but alarm information has not occurred on one of the two routes input to the service selector, and an alarm has occurred on the other route. When information is generated, data sent from the former route is selected.
[0048]
Further, when alarm information is generated in both paths, the priority of the alarm information is judged, and data that has passed through a path with a low priority of the alarm information is selected.
In FIG. 4, for the sake of simplicity, it is assumed that alarm presence / absence information from the paths 12, 17, and 11 is given from the CPU to the service selector SS.
Hereinafter, it is assumed that “1” is given as information indicating “alarm present” and “0” is given as information indicating “no alarm”.
[0049]
As shown in FIG. 3, when a failure occurs in one ring, the data of the path 19 is turned back at the node A2 and relieved to the node A1 through the path 17. For this reason, the alarm replacement unit 101 in FIG. 4 is configured so that the alarm monitoring timer unit 102 that monitors the alarm of the route 12 can monitor the alarm of the route 17 when the normal failure has not occurred. One of the alarms of the route 12 and the route 17 is selected by using the failure occurrence notification from.
[0050]
For example, when no failure has occurred in the ring, “0” (no failure) is output in the failure occurrence notification from the CPU in FIG. Is output.
When a failure as shown in FIG. 3 occurs, “1” (failure present) is output to the failure occurrence notification from the CPU, and an alarm of the path 17 is output to the output of the alarm replacement unit 101. The alarm of the route 12 or the route 17 selected using the failure occurrence notification from the CPU is sent to the alarm monitoring timer unit 102 as it is. The alarm replacement unit 101 can be realized by one selector as the simplest configuration.
[0051]
The alarm monitoring timers 102 and 103 monitor the duration of the alarm that has occurred. That is, the alarm input is monitored for a set time given by the CPU, and a trigger signal for switching or switching back a ring line is generated when an alarm occurs for a predetermined time or more. .
For example, the alarm monitoring timer unit 103 outputs a trigger signal “1” for switching the line when an alarm from the route 11 is detected for a predetermined time or more. If it is not detected, “0” is output.
[0052]
The alarm monitoring timer unit 102 monitors the alarm selected by the alarm reading unit 101 and outputs a similar trigger signal.
The alarm monitoring timer units 102 and 103 may be configured using so-called timer elements, but can be easily configured using a RAM as will be described later.
The working / protection alarm recognizing unit 104 determines whether the trigger signal input from the alarm monitoring timer units 102 and 103 is for the working line or the protection line.
[0053]
Although not shown in FIG. 4, the current / spare setting information of the current ring line is supplied from the CPU to the work / spare alarm recognition unit 104.
For example, when the working / standby setting given by the CPU is “0”, the path 11 in FIG. 1 is the working line and the path 12 is the standby line. At this time, of the two paths for transferring data from ring B to ring A, the path directly connected from node B1 to node A1 becomes active, and if there is no failure, it passes this active path 11. The selected data can be selected by the service selector 1.
[0054]
On the contrary, when the working / standby setting is “1”, the path 11 is the protection line and the path 12 is the working line.
The working / preliminary alarm recognition unit 104 can be constituted by, for example, two selectors as will be described later.
[0055]
The switching / switchback control signal generation unit 105 generates a control signal for switching or switching back a line using the trigger signal obtained from the active / preliminary alarm recognition unit 104. For example, “0” is output as the control signal for switching back to the working line, and “1” is output as the control signal for switching to the protection line. Also here, although not shown in the figure, information on the working / preliminary setting is given from the CPU.
This switching / switchback control signal generation unit 105 can be configured by a JK flip-flop and several logic elements, as will be described later.
[0056]
The line selection uses the control signal output from the switching / switchback control signal generation unit 105 to switch or switch back the path at the node A1. For example, when a switchback signal (“0”) is output as a control signal, the working path 11 and the path 15 on the ring are connected.
When a switching signal (“1”) is output as a control signal, the backup path 12 and the path 15 on the ring are connected.
[0057]
In the case where the data frames transmitted through the rings are one independent channel without being chained, the concatenation control unit 106 in FIG. 4 may not be provided, and five function blocks (101 to 105) are used. A service selector (SS) 1 can be configured.
However, since data in the SDH frame format is transferred in a chained manner, a concatenation control unit 106 as shown below is required.
[0058]
In general, when a chained channel is transferred from different paths by line switching / switchback operation, the continuity of the channel is lost, and normal data transfer cannot be performed. Therefore, it is necessary for all of the plurality of chained channels to be transferred through the same path, and concatenation control is performed to match the transfer path of the channel following the path to which the first channel is transferred.
[0059]
The concatenation control unit 106 operates to match the control signal output from the switching / switchback control signal generation unit 105 to the first channel for the channel to be chained. The concatenation control unit 106 can be realized by a plurality of selectors provided for each group to be chained.
The above is the functional block of the service selector SS of the present invention.
[0060]
A circuit diagram of one embodiment for realizing this function is shown in FIG.
The following description is based on the service selector SS provided in the node A1, but the service selector SS provided in the other nodes (A2, B1, B2) has the same configuration and function. In FIG. 5, the alarm replacement unit 101 is realized by one selector 51.
[0061]
As described above, the alarm information of the route 12 and the route 17 is input to the selector 51, and either one of the alarm information is selected by the failure notification signal sent from the CPU. The alarm information is given from another alarm detection unit in the node, but is given separately for each channel as a binary signal indicating “0” or “1”.
[0062]
For example, assuming that n-channel data is transmitted and received, alarm information corresponding to each channel of data flowing on the path 12 is input to the selector 51 through n signal lines. Similarly, the alarm information of the route 17 is also input to the selector 51 through n signal lines.
[0063]
The failure occurrence notification signal sent from the CPU is also a binary signal. For example, “0” indicates that no failure has occurred on ring A, and “1” indicates that a failure has occurred on ring A. Indicates that When no failure has occurred on ring A (that is, failure occurrence notification signal = “0”), the selector 51 is caused to function so as to select the working path 12 of ring A as usual.
[0064]
When a failure occurs on ring A (that is, failure occurrence notification signal = “1”), the selector is caused to function so as to select the spare route 17 of ring A in order to make a loopback connection. From the selector 51, the alarm information of the selected route is directly output to the alarm monitoring timer unit 102 through n signal lines.
The alarm reading unit 101 is used for line fault detection / line switching on one ring line, and does not directly contribute to line switching or switch-back for interconnection between rings.
[0065]
In FIG. 5, the alarm monitoring timer unit 102 can be composed of monitoring timers 58 and 59 and MUXs 65 and 66 that perform time division multiplexing. The MUXs 65 and 66 are for time-division multiplexing the n pieces of alarm information output from the selector 51 and outputting the information on one signal line. That is, alarm information for n channels is serialized and output on one signal line.
[0066]
The monitoring timers 58 and 59 monitor the occurrence of alarm information for a certain period of time, and can be configured using, for example, the RAM 81, the adder 82, and the decoding circuit 83 shown in FIG. The address, the read / write control signal, and the read / write clock are supplied from the time division processing timing pulse generator 73 shown in FIG.
[0067]
In addition to the read / write clock, the time division processing timing pulse generator 73 generates a clock pulse to be supplied to each MUX and the JK flip-flop of the switching / switchback control signal generator 105.
The “serial alarm” in FIG. 6 is an output of the MUXs 65 and 66 in FIG. 5 and has a value of “0” or “1”. An area for storing data is allocated to the RAM 81 for each channel, and an alarm count value for each channel is written therein.
[0068]
FIG. 7 shows a time chart for explaining the operation of the monitoring timers 58 and 59.
Now, assume that one frame is composed of three channels, and a serial alarm as shown in FIG. Here, since the serial alarm of channel 1 and channel 3 is “1”, an alarm is generated, and the serial alarm of channel 2 is “0”, indicating that no alarm is generated.
[0069]
First, when a channel 1 serial alarm is input to the adder 82, the count value stored in the channel 1 area is read from the RAM 81 at substantially the same timing, and this is also input to the adder 82.
In the adder 82, the serial alarm of channel 1 and the count value of channel 1 are added, and the addition result is written in the storage area for channel 1 of the RAM 81.
[0070]
In the case of the first frame in FIG. 7, since the data out value read when the serial alarm of channel 1 is “1” is “0”, “1” is written in the channel 1 area of the RAM.
Similar processing is performed for channel 2 and channel 3, and “0” is written in the channel 2 area of RAM 81 and “1” is written in the channel 3 area in the first frame.
[0071]
Further, such reading and writing processes for the RAM 81 are repeated. As shown in FIG. 7, if the same alarm is generated up to the 100th frame, the count value 100 is written in the area on the RAM 81 of the channel 1 and the channel 3.
[0072]
On the other hand, the output of the adder 82 is also input to the decode circuit 83, and the decode circuit 83 checks whether or not a count value corresponding to a preset time is input. When a count value corresponding to the set time is input, the decode circuit 83 outputs a trigger signal “1”.
For example, assuming that the count value to be decoded is 100, the trigger signal “1” for switching or switching back the line is output from the decode circuit 83 when alarms for 100 frames are counted.
[0073]
The above is the embodiment of the alarm monitoring timer unit 102 using the RAM. However, the present invention is not limited to this, and can be realized using a logic element such as a counter or a flip-flop. However, the configuration using the RAM shown in FIG. 6 is superior in that the circuit scale is smaller.
[0074]
In FIG. 5, the active / preliminary alarm recognition unit 104 can be realized by two selectors 52 and 53. Here, both the selectors 52 and 53 use the trigger signal output from the monitoring timers 58 and 59 as an input signal.
In addition, the current / preliminary setting data is given from the CPU, and it is determined whether the trigger signal input based on the current / preliminary setting data is for the working line or the protection line.
[0075]
For example, when the working / standby setting is “0”, the working line is the path 11 and the protection line is the path 12, and when the working / standby setting is “1”, the working line is the path 12, and the protection line is It is assumed that the line is path 11.
At this time, if the input trigger signal is determined to be for the working line, the trigger signal “1” is output from the selector 52, and if it is determined to be for the protection line, the trigger signal is output from the selector 53. “1” is output.
[0076]
In FIG. 5, the test control unit 107 forcibly switches / switches lines under the control of the CPU regardless of the actual line alarm state, and is necessary for the so-called line test. Circuit. Therefore, this is not particularly necessary when the line is switched / switched back according to the actual alarm state change. This operation will be described later.
[0077]
In FIG. 5, the switching / switchback control signal generation unit 105 can be configured by an AND circuit, an OR circuit, an exclusive OR circuit, and a flip-flop. When there is no test control unit 107, the outputs of the selectors 52 and 53 are directly output to the switching / switchback control signal generation unit 105.
Here, when the output of the JK flip-flop 54 is “1”, it means switching to the protection line, and when it is “0”, it means switching back to the working line.
[0078]
The exclusive OR circuit 55 takes an exclusive OR of the above-mentioned current / preliminary setting data from the CPU and the JK flip-flop, and outputs a control signal for line switching or switch back. In the above setting, when the control signal is “0”, it means a signal for selecting the path 11, and when it is “1”, it means a signal for selecting the path 12.
[0079]
The OR circuit 56 takes the logical sum of the switch-back request signal from the CPU and the trigger signal from the selector 53, and switches the line back to the working line when the switch-back request signal is "1". It plays a role.
The AND circuit 57 serves to switch the line back to the working line side when trigger signals are generated from both the selectors 52 and 53.
[0080]
It is assumed that the current / preliminary setting from the CPU is “0”. That is, it is assumed that the route 11 is a working line and the route 12 is a protection line. At this time, if an alarm is generated on the working path 11 side, the monitoring timer 59 generates a trigger signal “1” for line switching. This trigger signal is output from the selector 52 because the current / preliminary alarm recognition unit 104 has a current / preliminary setting of “0” from the CPU.
[0081]
Further, the trigger signal “1” output from the selector 52 is input to the J terminal of the JK flip-flop 54 via the AND circuit 70 and the OR circuit 71. At this time, the output Q of the JK flip-flop 54 becomes “1” and is given to the exclusive OR circuit 55.
[0082]
On the other hand, since the current / preliminary setting from the CPU, which is the other signal input to the exclusive OR, is “0”, the exclusive OR with the output Q (= “1”) is taken and exclusive The logical OR circuit 55 outputs a control signal “1” indicating a switching request for selecting the path 12.
When the concatenation control is not performed, this control signal “1” is used as a switching / switchback control signal, and the connection to the path 15 is switched from the path 11 to the path 12.
[0083]
Next, a line switching operation will be described.
First, it is assumed that an alarm is generated in the path 11 and the switching operation is performed to switch to the path 12. If the alarm on the path 11 is recovered in this state, the trigger signal notifying the occurrence of the alarm disappears from the monitoring timer 59 described above. That is, the trigger signal “0” is output from the monitoring timer 59, and then, when an alarm of the path 12 occurs, the trigger signal “1” is output from the monitoring timer 58, and this trigger signal means a switchback request. Signal.
[0084]
When the trigger signal “1” from the monitoring timer 58 is input to the active / preliminary alarm recognition unit 104, the current / preliminary setting from the current CPU is “0”. "Is output.
The trigger signal “1” is supplied to the K terminal of the JK flip-flop via the OR circuits 56 and 72, and the output Q of the JK flip-flop becomes “0”. This output Q = "0" means a switchback request.
[0085]
In the exclusive OR circuit 55, the exclusive OR of the output Q “0” and the current / preliminary setting “0” from the CPU is taken, and the switching / switchback control signal generation unit 105 eventually outputs the control signal “ 0 "is output.
When the concatenation control unit 106 is not provided, this control signal “0” is used as a switching / switchback control signal, and the connection to the path 15 is switched back from the path 12 to the path 11.
[0086]
The output of the switching / switchback control signal generation unit 105 is separated into parallel signals for n channels by a timing pulse given from the time division processing timing pulse generation unit 73 to the enable terminal (EN) of the JK flip-flop. The
As described above, the generation of the switching / switchback control signal is realized based on the alarm information from the paths 11, 12, and 17 connected to the service selector (SS) 1.
[0087]
Next, an example of the operation and configuration of the concatenation control unit 106 will be described.
FIG. 8 shows a configuration diagram of an embodiment of the concatenation control unit 106. Here, a specific circuit example of “STS-3C setting” for chaining control signals for three channels and “STS-12C setting” for chaining control signals for 12 channels is shown.
[0088]
In FIG. 8, from the left side, a “switch / switchback control signal” output from the exclusive OR circuit 55 and corresponding to each of the channels 1 to 12 is input. Further, 90 in FIG. 8 is a selector group for setting an STS-3C, and 95 is a selector group for setting an STS-12C.
[0089]
The selector group 91 is used to chain all the switching / switchback control signals for the three channels 1, 2, 3 to the switching / switchback control signal for the first channel 1.
Similarly, the selector group 92 is for linking channels 4, 5, and 6, the selector group 93 is for linking channels 7, 8, and 9, and the selector group 94 is for linking channels 10, 11, and 12. .
[0090]
In the selector group 95, all the control signals from channel 2 to channel 12 are chained to the control signal of the first channel 1. From the right side of FIG. 8, a chained “switch / switchback control signal” is output.
[0091]
Specifically, in the case of “STS-3C setting”, channels 2 and 3 are chained to be the same as the alarm state of channel 1, and if the first channel 1 is in the line switching request state, 3 is also in a line switching request state, and data that has passed through the same line path as channel 1 is selected.
Channels 5 and 6 are chained to the alarm state of the first channel 4, channels 8 and 9 are chained to the alarm state of the first channel 7, and channels 11 and 12 are chained to the alarm state of the first channel 10. Is done.
[0092]
In the case of “STS-12C setting”, channels 2 to 12 are chained to be the same as the alarm state of the first channel 1, and if the first channel 1 is in the line switchback state, the actual channel 2 Regardless of the alarm state of 12, the channels 2 to 12 are in the same line switchback state, and the data that has passed through the same line path as channel 1 is selected.
[0093]
Next, the operation / configuration of the test control unit 107 in FIG. 5 will be described. The test control unit 107 includes several logical product (AND) circuits 61, 62, 63, 64 as shown in the figure.
The test control unit 107 is supplied with a test mode setting signal and a test mode switching signal from the CPU. The test mode setting signal is a signal for forcibly shifting to the test mode regardless of the actual switching operation. Here, the test mode setting signal is set to “1”.
[0094]
The switching signal in the test mode is a signal for designating switching or switching back of the line when the test mode is entered. Here, “1” means line switching, and “0”. Means line switchback.
[0095]
At the time of transition to the test mode, the test controller 107 performs the following operation. When the test mode setting signal becomes “1”, the AND circuits 61 and 62 are masked so that the trigger signal given from the active / preliminary alarm recognition unit 104 is not input to the switching / switchback control signal generation unit 105, and The circuits 63 and 64 are controlled so that the switching signal in the test mode given from the CPU is input to the JK flip-flop through the OR circuits 71 and 72.
[0096]
For example, when the switching signal in the test mode is “1”, “1” is input to the J terminal of the JK flip-flop through the OR circuit 71, and line switching control (switching from the path 11 to the path 12) is performed. To work.
When the switching signal in the test mode is “0”, “1” is input to the K terminal of the JK flip-flop through the OR circuit 72, and line switching control (switching from the path 12 to the path 11) is performed. To work.
The test control unit 107 is used when verifying interconnections between rings, such as when a ring system is introduced or when a ring system is maintained.
Although the embodiment in which the ring system of the present invention is applied to SDH has been described above, the ring system of the present invention can also be applied to a US standard SONET (Synchronous Optical Network).
[0097]
【The invention's effect】
According to the present invention, a ring system with high line use efficiency can be realized.
In addition, since the monitoring timer unit is provided, it is possible to prevent frequent occurrence of unnecessary line switching / switchback when an alarm occurs frequently.
[0098]
Since the alarm replacement unit is provided, an efficient relief path can be secured not only in the case of a mutual connection failure between rings but also in the case of a line failure in the ring. Furthermore, since the test control unit is provided, the ring system can be easily verified during maintenance.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an embodiment of a ring system of the present invention.
FIG. 2 is a configuration diagram of an embodiment of a node according to the present invention.
FIG. 3 is an explanatory diagram of a line connection example when a failure occurs in the ring system of the present invention;
FIG. 4 is a block diagram showing the configuration of an embodiment of a service selector according to the present invention.
FIG. 5 is a circuit configuration diagram of an embodiment of a service selector according to the present invention.
FIG. 6 is a circuit configuration diagram of an embodiment of a monitoring timer according to the present invention.
7 is a time chart for explaining the operation in FIG. 6. FIG.
FIG. 8 is a circuit configuration diagram of an embodiment of a concatenation control unit according to the present invention.
FIG. 9 is an operation explanatory diagram of a conventional ring system.
[Explanation of symbols]
LA1, LA2 Ring line of ring A
LB1, LB2 Ring line of ring B
1 Service selector SS
2 Service selector SS
58 Monitoring timer
59 Monitoring timer
73 Time-division processing timing pulse generator
81 RAM
82 Adder
83 Decoding part
90 STS-3C Setting Selector Group
91 STS-3C setting selector group
92 STS-3C setting selector group
93 STS-3C setting selector group
94 Selector group for STS-3C setting
95 STS-12C Setting Selector Group
101 Alarm replacement part
102 Alarm monitoring timer
103 Alarm monitoring timer
104 Current / preliminary alarm recognition unit
105 switching / switchback control signal generator
106 Concatenation control unit
107 Test control unit

Claims (5)

A first ring including a first node and a second node, and a second ring including a third node and a fourth node,
Two communication lines that flow data in different directions, respectively, and connected by a working path that connects the first node and the third node and a backup path that connects the second node and the fourth node In the ring system,
A connection switching circuit located in each of the nodes,
Using an alarm of data flowing through the two communication lines, an alarm reading unit that generates a control signal for turning back the communication line in the same ring when a line failure occurs in the same ring;
An alarm monitoring unit for detecting an alarm generated in the working path and the backup path and outputting respective alarm detection signals;
A current / preliminary alarm recognition unit for identifying whether the detected alarm has occurred on the working path or on the backup path using the alarm detection signal, and for outputting an identification signal;
Based on the identification signal, a switching control signal generation unit that generates a control signal for selecting a path used for data transmission between the rings ,
Generated by the switching control signal generation unit such that the plurality of data to be chained flowing between the first and second rings is data transmitted from either the working path or the backup path; It is composed of a control signal related to the top data and a concatenation control unit that replaces a control signal related to other data following the top data .
A ring system that monitors an alarm of data flowing on a working path and a backup path, and selects either the working path or the backup path to perform interconnection between the first ring and the second ring. Connection switching circuit. A test control unit that forcibly forms an alarm generation state regardless of whether or not an actual alarm is generated in the working path and the backup path, and provides a pseudo identification signal to the switching control signal generation unit; The connection switching circuit according to claim 1 .   The connection switching circuit according to claim 1, wherein the switching control signal generation unit includes a switching back unit that switches back to the working path based on a forced switching back control signal given from the outside.   The connection switching circuit according to claim 1, wherein the alarm monitoring unit includes a rewritable storage circuit that stores information indicating a duration of an alarm.   2. A BLSR ring system in which the connection switching circuit according to claim 1 is provided in each node on a plurality of rings constituting an SDH interface network, and the rings are interconnected by the connection switching circuit.

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