JPH10336225A - User channel signal protection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relieve a user channel signal composed of MS overhead bytes even when an optical transmission line fault or the like occurs by switching the MS overhead bytes while being interlocked with line switching using an APS byte. SOLUTION: When any fault occurs on an optical transmission line between respective nodes, the line switching of main signal is performed by exchanging APS bytes. MST parts 2-5 terminate the MS overhead bytes. When a ring switch state on the WEST side is judged, for example, an APS protocol processing part 1 performs control so that selector circuits 6 and 7 select signals from a user channel 1 and selector circuits 8 and 9 select signals from the MST parts 5 and 4 respectively. Signals from a user channel 2 are outputted for an active system on the EAST side, and signals from the user channel 1 are outputted for a reserve system on the EAST side. The MS overhead bytes at the reserve system on the EAST side are inputted to the WEST side and the MS overhead bytes for the active system on the EAST side are inputted to the EAST side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection system for protecting a signal even when an optical transmission line failure or the like occurs between nodes in an SDH network ring network system. One SPring (Multiplex Section)
The present invention relates to a user channel signal protection scheme for protecting a user channel signal communicated using an MS overhead byte in a shared protection ring network system.

[0002]

2. Description of the Related Art SDH standardized as a digital multiplexing technology capable of flexibly synchronously multiplexing and efficiently processing existing low-speed signals to various future high-speed service signals.
(Synchronous Digital Hier
Various developments have been made on digital telecommunications network systems using an archive (synchronous digital hierarchy).

[0003] A connection configuration between nodes having an optical transmission device in a network includes a linear configuration in which nodes are linearly arranged and an interval between them is connected by an optical transmission path, and a node in which the nodes are connected in a ring shape by an optical transmission path. There are typically two types of ring configurations. In the SDH network, it is very important to secure the communication and to guarantee the reliability of the line service when the line between the nodes fails, and in the ring-shaped network system, the WEST of each optical transmission device is required. A configuration in which two working and standby systems are provided for the input optical fiber and the output optical fiber on each of the optical and EAST sides, and a plurality of optical transmission devices are connected in a ring by the four optical fibers (optical transmission lines). When a failure occurs in the optical transmission path between nodes, the APS byte (Au
tomatic Protection Switch
A four-fiber MS-SPring network system that quickly switches lines by transmitting and receiving (Byte) to secure communication has been standardized.
As described in Japanese Patent Application Laid-Open No. 64321 and the like, an MSP (Multiplex Secti) by such a method is used.
On-protection (multi-section protection) is under development.

However, in the conventional SDH optical transmission device, ITU-T G. As described in 783,
MS Overhead Byte (Multiplex Sec)
Since the function of terminating the “overhead byte” is higher than the MSP, the conventional SDH optical transmission device does not have a protection function for the communication contents of the MS overhead byte.

[0005]

As described above, in the conventional SDH optical transmission device, the four-fiber MS-SPr
The MSP function using the APS byte called the STM (Synchronous Transp.
ort Module (synchronous transfer module) only protects the main signal.

For this reason, the four-fiber MS-SPring
Even if the MS overhead byte is provided as a user channel between adjacent nodes of the network system, the SOH
(Multiplex Sectio), which is a section that terminates (Section Overhead)
n; multiple sections) and exist in MST (Multi
plex Section Termination;
The content of the information embedded in the MS overhead byte terminated at the multi-section termination is not protected, and if an optical transmission path failure or the like occurs between adjacent nodes communicating as a user channel, the information between the nodes is not protected. There has been a problem that communication using the MS overhead byte becomes impossible and a signal of a user channel cannot be rescued.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problem, and can rescue a user channel signal transmitted during an MS overhead byte even when an optical transmission line failure occurs between adjacent nodes. It is an object of the present invention to provide a user channel signal protection method.

[0008]

According to the user channel signal protection method of the present invention, when a line is switched using an APS byte in a four-fiber MS-SPring network system, a user channel signal is interlocked with the line switching. The MS overhead byte used for the communication is switched.

In the user channel signal protection method according to the second aspect, the communication of the user channel by the MS overhead byte is performed in the normal state based on the APS protection state of the MS-SPring used by the optical transmission apparatus to protect the main signal. At the time, the communication is performed by the MS overhead on the working side of the span, and at the time of the span switch, the M on the spare side in the same direction as that during the normal state is communicated.
The S-overhead byte is used for communication, while the ring switch is used for communication using the spare side MS overhead byte in the opposite direction to that used in the normal state, and when the own node is in the through state, the WEST direction and the EAST direction are used. The spare side MS overhead byte is connected through.

The user channel signal protection system according to claim 3, wherein a first selection circuit for selecting the MS overhead byte to be output to the WEST side standby of the optical transmission device for the plurality of optical transmission devices; A second selection circuit for selecting an MS overhead byte to be output to an EAST-side backup of the transmission apparatus, and a WEST of the optical transmission apparatus
To select the MS overhead byte input to the side
, A fourth selection circuit for selecting an MS overhead byte input to the EAST side of the optical transmission device, and the APS protection state on the WEST side and the EAST side of the optical transmission device is a normal state, a span state Control means for controlling each of the selection circuits in a predetermined manner according to any of a switch state, a ring switch state, and a through state, wherein the control means transmits a signal to the west side in a normal state. If there is a channel signal, it is transmitted by the WEST side working MS overhead byte, and the first selection circuit is made to select this user channel signal. If there is a user channel signal to be transmitted to the EAST side, it is transmitted to the EAST side. MS
The second byte is transmitted by the overhead byte.
Select the user channel signal, and input the MS signal inputted from the WEST side to the third selection circuit.
The overhead byte is selected, and the fourth selection circuit is controlled to select the MS overhead byte input from the EAST side working. When the WEST side is in the span switch state, the overhead byte is selected as compared with the normal state. The selection of the third selection circuit is controlled to be switched to the MS overhead byte input from the WEST side standby, and the EAST
When the side is in the span switch state, the selection of the fourth selection circuit is controlled to be switched to the MS overhead byte input from the EAST side standby as compared with the normal state, and the WEST side is in the ring switch state. In this case, the user channel signal transmitted to the west side in the normal state is selected by the second selection circuit, and the selection of the third selection circuit is switched to the MS overhead byte input from the spare on the east side. And E
When the AST side is in the ring switch state, the user channel signal transmitted to the EAST side in the normal state is selected by the first selection circuit, and the selection of the fourth selection circuit is input from the WEST side standby. In the case of the through state, the selection of the first selection circuit is switched to the MS overhead byte input from the EAST side standby, and the selection of the second selection circuit is performed. The control is performed so as to switch to the MS overhead byte input from the WEST side standby.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 is a block diagram of a portion related to user channel signal protection in an optical transmission device to which the user channel signal protection system of the present invention is applied. In this part, communication of the user channel signal is controlled by the end of the MS overhead byte and the MS overhead byte. This optical transmission device is installed at each node in a four-fiber MS-SPring network system. Between each node, two current input / output optical fibers (optical transmission lines) and a spare input / output optical fiber 2 They are connected by four optical fibers. In this optical transmission device,
Illustration of other parts related to transmission / reception of APS bytes, switching of main signal lines and communication based on the APS byte is omitted.

In FIG. 1, 1 is a 4-fiber MS-SP.
APS that controls the following selection circuits and the like to execute user channel signal protection in the ring
It is a protocol processing unit (control means). The APS protocol processor 1 monitors and determines the state of the protection switch of the main signal by communicating with the processor which transmits / receives the APS byte and switches the line of the main signal in the optical transmission apparatus. Alternatively, it may be integrated with a processing device that performs transmission and reception of APS bytes and line switching of main signals.

Reference numeral 2 denotes an MST section for terminating the WEST side working MS overhead byte, 3 denotes an MST section for terminating the WEST side spare MS overhead byte, and 4 denotes an MST section for terminating the EAST side working MS overhead byte.
Is an MST section for terminating the MS overhead byte of the spare on the east side, 6 is a selecting circuit (first selecting circuit) for selecting the MS overhead byte to be output to the spare on the west side,
7 is a selection circuit (second selection circuit) for selecting the MS overhead byte to be output to the EAST side spare, and 8 is WES
A selection circuit (third selection circuit) for selecting the MS overhead byte input to the T side, and 9 is a selection circuit (fourth selection circuit) for selecting the MS overhead byte input to the EAST side.

Next, the operation of the first embodiment will be described.

When a failure occurs in the optical transmission path between the nodes, the line switching of the main signal is performed as in the conventional example by transmitting and receiving APS bytes between the processing units of each node. The APS protocol processing unit 1 uses MS-SPrin
g according to whether the protection switch of the main signal on the WEST side and the EAST side of the own node is in the normal state, the span switch state, the ring switch state, or the through state, as described below.
To 9 are controlled.

The optical transmission apparatus shown in FIG. 1 has a user channel signal transmitted to the WEST side and a user channel 2 transmitted to the EAST side as a user channel signal for transmitting information arbitrarily input by a user through an interface. Is set, the user channel 1 is output from the WEST side working and spare MS overhead bytes and the user channel 2 is set to EA in a normal state without an optical transmission path failure or the like.
It is assumed that the output is made by the ST side working and spare MS overhead bytes.

The APs for the normal state, the span switch state, the ring switch state, and the through state will be described below.
The processing of the S protocol processing unit 1 will be described.

1. [Normal State] When the APS protocol processing unit 1 determines that the state is the normal state, the selection circuit 6 selects the signal from the user channel 2 and the selection circuit 7 selects the signal from the user channel 2. Control is performed such that the selection circuit 8 selects a signal from the MST unit 2 and the selection circuit 9 selects a signal from the MST unit 4.

As a result, the signal from the user channel 1 is used for the WEST side working and the WEST side standby, and the signal from the user channel 2 is used for the EAST side working and the EAST side.
The MS overhead byte from the WEST side working is output to the WEST side, and the EAST side is output to the EAST side.
The MS overhead byte from the side working is input, and communication of the user channel is performed by the MS overhead byte in the normal state.

2. [Span Switch State] When the APS protocol processing unit 1 determines that the west side is in the span switch state, it controls the selection of the selection circuit 8 to switch to the signal from the MST unit 3 as compared with the normal state. That is, the selection circuit 8 selects the signal from the user channel 2 so that the selection circuit 6 selects the signal from the user channel 1, and the selection circuit 8 selects the signal from the MS so that the selection circuit 8 selects the signal from the user channel 2.
The selection circuit 9 selects the signal from the T unit 3 so that
Control is performed to select a signal from the T unit 4.

Thus, the MS input to the west side
As the overhead byte, an MS overhead byte reserved on the west side is selected. Others are the same as the normal state.

When the APS protocol processing section 1 determines that the EAST side is in the span switch state, the APS protocol processing section 1 controls the selection of the selection circuit 9 to switch to the signal from the MST section 5 as compared with the normal state. That is, as the selection circuit 6 selects a signal from the user channel 1, the selection circuit 7 selects a signal from the user channel 2, and the selection circuit 8 selects a signal from the MST section 2. Control is performed so that the selection circuit 9 selects a signal from the MST unit 5.

Thus, the MS input to the EAST side
As the overhead byte, a spare MS overhead byte on the EAST side is selected. Others are the same as the normal state.

3. [Ring Switch State] When the APS protocol processing unit 1 determines that the west side is in the ring switch state, the APS protocol processing unit 1 controls the selection circuit 7 to select a signal from the user channel 1 as compared with the normal state, and the selection circuit 8 Is controlled to select a signal from the MST unit 5. That is, the selecting circuit 8 selects the signal from the user channel 1 so that the selecting circuit 6 selects the signal from the user channel 1, and the selecting circuit 8 selects the signal from the user channel 1.
Selects the signal from the MST unit 5 so that the
Controls to select a signal from the MST unit 4.

As a result, the signal from the user channel 2 is output to the working side of the east side, the signal from the user channel 1 is output to the spare side of the east side, and the MS overhead byte inputted to the west side is used as the MS overhead byte.
MS that S overhead byte is input to the EAST side
The MS byte on the EAST side is selected as the overhead byte.

When the APS protocol processing unit 1 determines that the EAST side is in the ring switch state, the APS protocol processing unit 1 controls the selection circuit 6 to select a signal from the user channel 2 as compared with the normal state, and sets the selection circuit 9 to the MST state. Control is performed to select a signal from the unit 3. That is, as the selection circuit 6 selects a signal from the user channel 2, the selection circuit 7 selects a signal from the user channel 2, and the selection circuit 8 selects a signal from the MST unit 2. Control is performed so that the selection circuit 9 selects a signal from the MST unit 3.

As a result, a signal from the user channel 1 is output to the working side of the west side, and a signal from the user channel 2 is output to the protection side of the west side.
MS that S overhead byte is input to the EAST side
The WEST side spare MS overhead byte is selected as the overhead byte.

4. [Through state] When the APS protocol processing unit 1 determines that the signal is in the through state, the selection circuit 6 is controlled to select a signal from the MST unit 5 and the selection circuit 7 is controlled by the MST unit 3 as compared with the normal state.
Is controlled to select the signal from. That is, the selection circuit 6 selects a signal from the MST unit 5, the selection circuit 7 selects a signal from the MST unit 3, and the selection circuit 8 selects a signal from the MST unit 2. Control is performed so that the selection circuit 9 selects a signal from the MST unit 4.

As a result, a signal from the user channel 1 is output to the working side of the west side, and a signal from the user channel 2 is output to the working side of the east side.
MS that S overhead byte is input to the EAST side
The MS byte for the EAST side is selected as the overhead byte. The above is the same as in the normal state, but the MS overhead byte is connected between the WEST side spare and the EAST side spare through.

FIGS. 2 to 4 show states in which user channel signal protection is performed according to the first embodiment.
FIG. 3 is a conceptual diagram shown by nodes. At the nodes A, B, C and D in the figure, an SDH optical transmission device equipped with the user channel signal protection system of the present invention is installed.

FIG. 2 shows a normal state where there is no failure between the nodes. The working side MS overhead byte between node A and node B is provided as a user channel.

FIG. 3 shows a case where a failure occurs in the working optical transmission line between the nodes A and B. In this case, the APS byte communication causes the node A and the node B to be in a span switch state, and the user channel signal is controlled to be communicated using the spare MS overhead byte between the node A and the node B. The signal is rescued. The normal state remains between the nodes B and C, between the nodes C and D, and between the nodes D and A.

FIG. 4 shows a case where a failure has occurred in both the working and protection optical transmission lines between the nodes A and B. In this case, the node A and the node B enter a ring switch state by the communication of the APS byte, and the user channel signal is controlled to be communicated using the MS overhead byte on the spare side in the opposite direction. At this time, the node C and the node D are in a through state, and the WEST side spare MS overhead byte and the EAST side spare overhead byte are controlled to be through-connected, thereby relieving the user channel signal.

As described above, in the first embodiment, the MS overhead byte for providing the user channel in the optical transmission device is not fixedly assigned to the WEST side / EAST side optical transmission line, but is APS. In conjunction with the protection state of MS-SPring by transmission and reception of bytes, as the MS overhead byte for providing a user channel, the MS overhead of the working side in the direction to be transmitted in the normal state is used, and in the same direction in the span switch state. Using the MS overhead byte on the spare side, and in the ring switch state, the spare side M in the opposite direction
Use S overhead byte, WE if through
Since the switching is performed by connecting the MS overhead bytes of the ST side spare and the EAST side spare through connection, even if a transmission path failure or the like occurs between nodes communicating as a user channel, the MS overhead byte is used. It is possible to rescue the user channel signal communicated by the user.

In the first embodiment, in the normal state, the user channel signal is transmitted to both the working and standby directions in the direction in which the user channel signal is desired to be transmitted. Alternatively, the communication of the user channel signal is secured by switching the selection of 9, but also in the transmission of the user channel signal, the switching from the working to the standby is actively performed so that the communication of the user channel signal which is unnecessary for the communication of the user channel signal is actively performed. It goes without saying that various alternatives, such as a configuration and a switching method of the selection circuit, are possible within the scope of the present invention, such as a method of transmitting a dummy signal to the MS overhead byte.

[0037]

As described above, according to the user channel signal protection system of the first aspect, the AP in the four-fiber MS-SPring network system is used.
When performing line switching using the S byte, the MS overhead byte used for communication of the user channel signal is switched in conjunction with the line switching, so that an optical transmission path between nodes communicating as a user channel has a failure. Even in the case of occurrence, there is an effect that the communication of the user channel signal can be secured by using the MS overhead byte of another line and the user channel signal can be relieved.

According to the user channel signal protection method of the present invention, when the line switching state using the APS byte is the normal state, the optical transmission apparatus sets the working side MS overhead byte in the direction in which the user channel signal is to be transmitted. And in the case of the span switch state, the MS on the spare side in the direction in which the user channel signal is to be transmitted.
In the ring switch state, the communication is performed by the spare MS overhead byte in the direction opposite to the direction in which the user channel signal is to be transmitted, and in the through state, the spare MS overhead byte is communicated by the through connection. Therefore, the switching of the MS overhead byte used for communication of the user channel signal is executed in the same manner as the switching of the main signal by transmitting and receiving the APS byte, so that the user channel signal can be rescued even in the case of an optical transmission line failure or the like. effective.

According to the user channel signal protection system of the third aspect, the first selection circuit for selecting the MS overhead byte to be output to the WEST side standby of the optical transmission device, and the optical transmission device. Equipment EA
A second selection circuit for selecting an MS overhead byte to be output to the ST side standby, a third selection circuit for selecting an MS overhead byte to be input to the WEST side of the optical transmission device, and an EAST of the optical transmission device M input to the side
A fourth selection circuit for selecting an S overhead byte, and control means for controlling each of the selection circuits, wherein a line switching state using the APS byte on the west side and the east side of the optical transmission apparatus is in a normal state. The control means controls each of the selection circuits 6 to 9 in a predetermined manner according to whether the state is a span switch state, a ring switch state, or a through state. Accordingly, there is an effect that a user channel signal can be relieved in the case of an optical transmission line failure or the like.

[Brief description of the drawings]

FIG. 1 is a block diagram of a portion related to user channel signal protection in an optical transmission device to which a user channel signal protection method according to the present invention is applied.

FIG. 2 is a conceptual diagram showing four nodes in a state where protection of a user channel signal is performed according to the present invention.

FIG. 3 is a conceptual diagram showing four nodes in a state where protection of a user channel signal is performed according to the present invention.

FIG. 4 is a conceptual diagram showing four nodes in a state where protection of a user channel signal is performed according to the present invention.

[Explanation of symbols]

 1 APS protocol processing unit (control means) 2, 3, 4, 5 MST unit 6 selection circuit (first selection circuit) 7 selection circuit (second selection circuit) 8 selection circuit (third selection circuit) 9 selection Circuit (fourth selection circuit) A, B, C, D nodes

Claims (3)

[Claims] 1. An APS byte in a four-fiber MS-SPring network system formed by connecting a plurality of optical transmission devices in a ring by using four optical transmission lines including current and standby input / output optical transmission lines. A user channel signal protection method characterized in that, when performing the used line switching, the MS overhead byte used for communication of the user channel signal is switched in conjunction with the line switching. 2. A method according to claim 1, wherein the plurality of optical transmission apparatuses communicate with each other by a working MS overhead byte in a direction in which a user channel signal is to be transmitted when a line switching state using an APS byte is a normal state, and when the line switching state is a span switch state. Is the spare MS in the direction in which the user channel signal is to be transmitted.
Communication is performed by an overhead byte. In the ring switch state, communication is performed by a spare MS overhead byte in the direction opposite to the direction in which the user channel signal is to be transmitted. In a through state, the spare MS overhead byte is communicated by a through connection. 2. The method according to claim 1, wherein
User channel signal protection scheme as described. 3. The optical transmission device according to claim 1, wherein the plurality of optical transmission devices include a first selection circuit that selects an MS overhead byte to be output to a WEST side standby of the optical transmission device, and an EA of the optical transmission device.
A second selection circuit for selecting an MS overhead byte to be output to the ST side standby, a third selection circuit for selecting an MS overhead byte to be input to the WEST side of the optical transmission device, and an EAST of the optical transmission device M input to the side
A fourth selection circuit for selecting an S overhead byte, and the AP on the west side and the east side of the optical transmission device.
Control means for controlling each of the selection circuits according to whether the line switching state using the S byte is a normal state, a span switch state, a ring switch state, or a through state. In the normal state, if there is a user channel signal to be transmitted to the WEST side, the user channel signal is transmitted by the WEST side active MS overhead byte, and the first selection circuit selects the user channel signal to transmit the user channel signal to the EAST side. If there is a channel signal, the MS signal is transmitted by the EAST-side working MS overhead byte, and the second selection circuit is made to select the user channel signal, and the third selection circuit is inputted to the WEST-side working byte by the MS overhead byte. From the EAST side working input to the fourth selecting circuit. When the WEST side is in the span switch state, the selection of the third selection circuit is performed by the MS overhead byte input from the WEST side spare when the WEST side is in the span switch state. When the EAST side is in the span switch state, the selection of the fourth selection circuit is controlled to be switched to the MS overhead byte input from the EAST side standby when compared with the normal state. When the west side is in the ring switch state, the user channel signal transmitted to the west side in the normal state is selected by the second selection circuit, and the selection of the third selection circuit is inputted from the EAST side standby. If the EAST side is in a ring switch state, In this case, the user channel signal transmitted to the EAS side in the normal state is selected by the first selection circuit, and the selection of the fourth selection circuit is switched to the MS overhead byte input from the WEST side standby. In the case of the through state, the selection of the first selection circuit is switched to the MS overhead byte input from the EAST side standby, and the selection of the second selection circuit is input from the WEST side standby. 3. The user channel signal protection method according to claim 2, wherein control is performed to switch to the MS overhead byte.