JP2709212B2 - Path route switching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Industrial applications] With the development of ultra-high-speed optical transmission technology,
Large capacity transmission lines exceeding several Gb / s have been introduced. Such a large capacity transmission line is indispensable for providing economical digital communication, but on the other hand, if a failure occurs in the transmission line, a large number of users will be damaged. Therefore, it is necessary to quickly recover from a transmission line failure and increase reliability. A switching device (generally, a DCS (Digital Cross-Connect Device) or the like) introduced into a transmission path network is controlled by an external path (for example, the International Telegraph and Telephone Consultative Committee (CCITT) recommendation G.10).
(VC-32 path specified in 707, 708, 709), and has the function of changing the path of the path accommodated in the failed transmission path, thereby bypassing the failed transmission path. It is possible to quickly recover from a failure. Specifically, when a transmission path failure is detected, the switching device adjacent to the failed transmission path is controlled to switch the path accommodated in the failed transmission path to a path bypassing the failed transmission path. In this way, the transmission path network can be dynamically reconfigured, and the reliability, flexibility, and economy can be improved.

[0002] The present invention relates to a path switching method for switching such a path, and more particularly to a path switching device for preventing a path from being switched to an incorrect path during switching.

[0003]

2. Description of the Related Art CCITT G. 707, 708, 70
FIG. 3 shows a configuration example of the path switching method for a path signal having the NNI frame configuration specified in FIG. 9 taking a VC-32 path as an example. Path generation point 11 of path generation termination device 1
In the switching device 2 that receives the VC-32 path signal a generated in the above, the VC-32 path signal a is output to the transmission line C. Similarly, the VC-32 path signal a is transmitted to the input terminal 61 of the path generation / termination device 6. The switching device is D
It is composed of CS (Digital Cross Connect Device) etc.
By operating a time switch or a space switch based on external control (not shown), the connection between the input terminal and the output terminal is arbitrarily changed.

As an example, a path A is input to a path generation / termination device 6 via a switching device 2 and a switching device 3. On the other hand, the path B is the switching device 2, the switching device 4, the switching device 5
And input to the path generation / termination device 6 via the switching device 3. That is, the path A uses the transmission path C, and the connection in each switching device is a solid line. The path B uses the transmission path D1, the transmission path D2, and the transmission path D3, and the connection between the input / output terminals in each switching device is indicated by a dotted line. Here, the transmission path C was initially used, but since a failure such as a cable disconnection has occurred in the transmission path C, the carried VC-32 path signal a is switched from the path A to the path B. The case of performing the operation will be described.

First, by external control (not shown),
The switching devices 4 and 5 connect the input terminal 41 and the output terminal 42 and the input terminal 51 and the output terminal 52, respectively, and create a path route from the output terminal 26 of the switching device 2 to the input terminal 35 of the switching device 3. . However, at this point, no VC-32 path signal is flowing through the created path route.
Next, the connection between the input terminal 21 and the output terminal 22 of the switching device 2 is switched to the connection between the input terminal 21 and the output terminal 26 and the connection between the input terminal 31 and the output terminal 32 of the switching device 3 by an external control (not shown). Is switched to the connection between the input terminal 35 and the output terminal 32. In this way, the VC-32 path signal a generated at the path generation point 11 of the path generation / termination device 1 flows through the path route B to the path termination point 61 of the path generation / termination device 6, and the path Is completed.

[0006]

In such a conventional method, when a path is switched to a new path, an erroneous path is formed if connection settings in a passing device are incorrect. There is a problem in that it is difficult to discover that an incorrect path has been formed, and it is difficult to specify an incorrect point.

In FIG. 3, a case where the VC-32 path signals a and b are simultaneously switched from the path path A to the path path B and erroneously connected will be described as an example. For example, in the switching device 4, where the input terminal 41 and the output terminal 42 are originally connected and the input terminal 43 and the output terminal 44 are to be connected, the input terminal 41 and the output terminal 44 are connected. A case where the output terminal 43 is connected to the output terminal 43 will be described.

If path switching is performed with such an erroneous connection, the VC-32 path signal “a” originally generated at the path generation point 11 of the path generation / termination device 1 is terminated by the path generation / termination device 6. It should be input to the point 61, but it is input to the path termination point 62 of the path generation terminal 6.
Similarly, the VC-3 path signal b generated at the path generation point 12 of the path generation / termination device 1 is input to the terminal point 61 of the path generation / termination device 6. Therefore, the user information carried by these path signals will be carried to different places. On the other hand, the fact that these path signals are generated at the path generation point and terminated at the path termination point is no different from the normal case, and no alarm is generated in error monitoring of the path signal or the like. Therefore, it is not possible to detect that the device is being erroneously carried, and to identify which switching device is performing the erroneous connection even if the user detects the erroneous connection by pointing out the erroneous connection. Was also very difficult.

As a method of preventing such an erroneous connection in advance, a connection between the output terminal 26 and the input terminal 35 and an output terminal 28 before the connection change in the switching device 2 and the switching device 3 are executed.
There is a method of testing between the input terminals 36 to confirm that no bit error or the like occurs. However, for this test, it is necessary to insert a test signal into the output terminal, connect a measuring instrument to the input terminal, and perform other operations, such as starting and ending the test and confirming the test results. And the control for performing the test is complicated. In addition, since it takes time to perform such a troublesome test, it is time-consuming to recover in a case where it is urgent such as when the path accommodated in the transmission path is bypassed in the event of a failure. There are drawbacks.

An object of the present invention is to overcome these problems and to provide a device that does not require complicated control from the outside and that quickly switches a path to an incorrect path at the time of switching.

[0011]

According to the present invention, an invention exists on each of a transmission side and a reception side. In a transmission side apparatus, that is, a switching apparatus or a path generation apparatus, a path is uniquely identified in a part of a path signal frame. Means for assigning a path identifier to be displayed on the receiving side, the switching device on the receiving side comprises means for monitoring the path identifier, means for detecting a failure state of the path signal, and means for accumulating path identification signal data. If the path identifier is detected, the path identification signal data stored in the storage unit is prohibited, and the path identifier transmitted via the switching destination path is After confirming that the path identifier stored in the storage means of the switching source is the same as the path identifier, switching the path to the switching destination path to prevent erroneous switching. It is an apparatus scheme.

[0012]

The transmitting side assigns a path identifier, and the receiving side switches after confirming the path identifier, so that erroneous switching can be prevented.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment of the present invention, CCITT G. 7
NNI (Network) defined in 07, 708, 709
A case where the present invention is applied to a signal having a (Node Interface) frame configuration will be specifically described. As the path signal in the present invention, signals of various speeds including sections can be used. The section overhead and the path overhead shown in Table 1 are defined for these signals, and there is room for a plurality of bytes to be used for various purposes. As a technical idea that has not existed in the past, a necessary path identification signal can be efficiently inserted using these bytes. In the present embodiment, an example in which the “VC-32 path connection path confirmation byte J1” is used will be described.

[0014]

[Table 1]

The above-mentioned recommendation CCITT G. 707,
708 and 709 are described in detail in the “Blue Book” published by the International Telecommunication Union. FIG. 3 shows the operation of the present invention.
This will be described with reference to the path route switching configuration diagram of FIG. When generating the VC-32 path signal a at the path generation point 11 of the path generation terminal point device 1, a path identifier capable of uniquely identifying the path is added to the J1 byte of the path overhead. This means that the path generating / terminating device on the transmitting side assigns a path signal to a part of a frame with a path identifier for uniquely indicating the path. As described above, when it is not expected that a path identifier is assigned in the path generation termination point device 1, a path identifier can be assigned according to the second embodiment.

FIG. 1 shows an embodiment of the block configuration of the switching device 3 on the receiving side. The monitor circuit A73 monitors the VC-3 path signal a passing through the path A which is the switching source path, separates the path identifier from the J1 byte, and
Output to 75. The error detection circuit A71 detects an abnormal state of the path signal such as “path signal disconnection (path AIS)” or “bit error” from the monitored path signal, and detects no abnormality in the frame that transmitted the path identifier. Only the switch A75 is operated, and the path identifier is stored in the memory A77. Because of this operation, the VC can be
If the -32 path signal a is incorrect and an abnormal path identifier is sent, the path identifier stored in the memory A77 is not rewritten to an incorrect value.

Each circuit for the path B operates in the same manner, but is not connected to the path generation point.
Since a path signal interruption (path AIS) is sent, writing to the memory B is not executed. In order to explain these operations on the receiving side, FIG. 3 showing the entire system is used.
In order to switch the path in FIG. 3, a path from the output terminal 26 of the switching device 2 to the input terminal 35 of the switching device 3 is created according to external control (not shown),
The input terminal 21 of the switching device 2 is connected to the output terminal 26. At this time, it does not necessarily mean that disconnection between the input 21 and the output 22 is performed. That is, the same information may flow through both path routes. The switching device 3 receives an instruction to connect the input terminal 35 to the output terminal 32, but does not actually perform the connection change at this time.

Since the path B is connected to the path generation point 11, the path identifier of the VC-32 path signal a is
Memory B via monitor circuit B74 and switch B76
78 is written. At this time, when switching is performed in the switching device 2, the identifier of the VC-32 path signal does not flow through the path A, but the error detection circuit A
When the 71 detects the path signal interruption (path AIS), the identifier previously written is stored in the memory A77.

The switching device 3 changes the input terminal 35 to the output terminal 32
The comparator 79 starts to compare the contents of the memory A77 and the memory B78 from the time when the instruction to connect to the memory A77 and the memory B78, and the identifier of the VC-32 pass signal a is written to the memory B78. Are matched, the selector 80 composed of a time switch, a space switch, and the like is controlled, the input terminal 31 and the output terminal 32 are disconnected, and the connection between the input terminal 35 and the output terminal 32 is switched.

If an erroneous connection is made by a switching device in the middle of the path B, the contents of the identifier written in the memory B78 do not match the contents of the memory A77.
0 does not work. By utilizing this, that is, by using means such as setting a timeout when there is a mismatch for a predetermined time after the switching control command is received, it is possible to recognize that an erroneous connection has occurred in the switching device in the middle. Further, by sequentially monitoring the J1 byte path identifier in the middle of the switching device, it is possible to easily identify the switching device that has made an erroneous connection.

Next, a second embodiment will be described with reference to FIG. An embodiment in which the path generation termination point device is not involved, that is, the case where the path switching is performed without error by only the switching device will be described with reference to FIG. In this case, the insertion of the path identifier into the J1 byte is performed at the input terminal 21 of the switching device 2. At this time, it is necessary to simultaneously change the “error monitoring byte B3 in the VC-32 path section”.
The VC-32 path signal is monitored end-to-end (in this example, between the path generation terminal devices 1 and 6) using bit-interleaved parity. Therefore, if a path identification signal is inserted into the J1 byte in the middle, monitoring cannot be performed normally without any change, and the B3 byte needs to be rewritten.

Insertion of path identifier into J1 byte and B3
The method of the byte replacement process will be described with reference to FIG.
The input VC-32 path signal is checked by a parity check circuit 91 to determine whether an error has occurred up to this point. The path identifier storage circuit 92 sends a preset path identification signal to the identifier insertion circuit 93, and the identifier insertion circuit 93 inserts the path identifier into the J1 byte. The parity changing circuit 94 recalculates the interleaved parity of the VC-32 path signal in which the path identification signal is inserted into the J1 byte, and puts the calculation result as parity bits in the B3 byte of the next frame. At this time, if the parity check circuit 91 detects an error, the monitoring state in the previous section is preserved by inverting 1/0 of the corresponding bit and putting it on.

[0023]

As described above, according to the present invention,
A path identification signal that uniquely identifies the path signal is given to a part of the frame of the path signal, and the switching device on the receiving side compares the switching source and switching destination path identification signals,
Since switching to the switching destination path is performed only when they match, it is possible to prevent switching the path to the wrong path at the time of switching without performing complicated control from the outside,
This has the effect that switching can be performed quickly.

[Brief description of the drawings]

FIG. 1 is a block diagram of a receiving-side switching device according to an embodiment of the present invention.

FIG. 2 is a block diagram for explaining a method of inserting a path identifier into a J1 byte.

FIG. 3 is a path route switching configuration diagram for explaining a path switching method of a path;

[Explanation of symbols]

 1, 6 path generation and termination device 2, 3, 4, 5 switching device A, B path path C, D transmission path 71, 72 error detection circuit 73, 74 monitor circuit 75, 76 switch 77, 78 memory 79 comparison circuit 80 selector 91 parity check circuit 92 path identifier storage circuit 93 path identifier insertion circuit 94 parity replacement circuit

Claims (3)

(57) [Claims] In a path route switching method for changing a path route between two opposing switching devices, a transmitting-side device includes means for performing a parity check of a path signal and a part of a path signal frame. Means for inserting a path identifier uniquely indicating the path into a part of the frame of the path signal,
Means for correcting an error monitoring byte that has become invalid with the insertion of the path identifier. 2. In a path route switching method for changing a path route between two opposing switching devices, a switching device on a receiving side monitors a path identifier, a device for storing the path identifier, and a storage device. And a means for generating a switching execution signal when the path identifier of the switching source path route and the path identifier of the switching destination path route stored in the switching path are the same. 3. The path route switching device according to claim 2, wherein the means for monitoring the path identifier includes:
A path route switching device comprising: means for detecting a state of a path signal; and means for prohibiting updating of stored path identifier data when a failure of the path signal is detected.