JP3399901B2 - Optical transmission network system - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a point-to-point optical transmission device.
The present invention relates to an optical transmission network system using the above , and more particularly to a technique for configuring an optical transmission network system that can be restored when a failure occurs in an optical fiber transmission line.

[0002]

2. Description of the Related Art An optical transmission network system is used as a backbone of communication infrastructure. In such an optical transmission network system, even if a failure such as an optical fiber break occurs, it is necessary to recover the failure by some method and ensure high reliability. SONET (Sync
A self-relief ring using hronous Optical NETwork has been proposed (for example, TH. Wu, "Fiber Network
Service Survivability ", Artech house (1992)). In this method, when an optical fiber fails, an electrical switch is used to switch the failed route to a detour route to ensure high reliability. Since it is becoming difficult to switch signals with electric switches as the capacity and speed of transmission devices increase, a method of switching high-speed signals using optical switches has also been proposed (for example, AH Elrefaie, IEEE I
See CC '93, PP.1245 (1993)).

[0003]

Generally, in an optical transmission network system covering a wide area, base stations are provided at a plurality of points, and these base stations are connected by optical fibers to form a network. . In this case, according to the conventional concept of a general optical transmission network system, a node device arranged in each base station is a network element (an element that constitutes one constituent unit of a network having an independent control device, It has a function of performing recovery processing at the time of a failure by the control device), and a method of constructing the entire network by connecting many node devices with a long-distance optical fiber is adopted. However, when constructing a network based on such an idea, the degree of freedom in designing and expanding the network is greatly limited.

For example, let's consider a case where a node device a located at the point A and a node device b located at the point B are connected by an optical fiber transmission line and communication is performed between them. In this case, if the format of the optical transmission signal supported by the optical transceiver provided in the node equipment a and the format of the optical transmission signal supported by the optical transceiver provided in the node equipment b are not compatible. , Signal transmission cannot be performed between the two. Further, when some failure occurs in the optical fiber transmission line, it is necessary to perform some processing for the failure recovery in each of the node devices a and b, but a specific procedure for performing such failure recovery processing. If there is no consistency between the two (for example, the format of the signal for informing the occurrence of a failure, the basic operation for failure recovery, etc.), correct failure recovery processing cannot be performed.

Generally, each vendor designs and manufactures equipment on a node device basis. Therefore, if the vendor designing the node device a and the vendor designing the node device b are different, the optical transceivers in each node device may be different. The format of the corresponding optical transmission signal and the specific procedure for performing the failure recovery processing also differ. Therefore, when constructing the entire network, either all node equipment should be procured from the same vendor, or a specific method for performing optical transmission signal format and failure recovery processing should be discussed in consultation between multiple vendors. There is no choice but to take measures such as standardizing the procedure and then having the node device delivered based on this standardized specification. However, in optical transmission network systems over a wide area,
It is impractical to source all node equipment from the same vendor. On the other hand, it takes a lot of time to standardize between vendors, and various restrictions are imposed on individual vendors for this standardization. As described above, when a network is constructed by the conventional way of thinking, the degree of freedom in designing and expanding the network is significantly limited.

Therefore, an object of the present invention is to provide an optical transmission network system which has a high degree of freedom in design and expansion and which is also highly reliable .

[0007]

[Means for Solving the Problems] (1) A first aspect of the present invention is to provide base stations at a plurality of points, and
Define an annular route that connects in a ring, and follow this annular route.
Used for normal operation and used in case of failure
A standby optical fiber for each base station
Right adjacent base station adjacent to the right-hand side of the circular route and left-handed
The left side when you define the left side adjacent base station
For both adjacent base stations on the right,
Optical signals can be sent and received using both
In the optical transmission network system configured to receive
In the above, a first terminal station device installed at the first point, a second terminal station device installed at the second point, and an optical fiber transmission line connecting these terminal station devices are provided. Prepared, first
Has a function to perform bidirectional communication between a point and a second point
Prepare a point-to-point optical transmission device that
A point-to-point optical transmission prepared for connecting to an adjacent base station.
The transmitter is used as an optical transmission device for right-side connection, and each base station
And the two adjacent base stations on the left side of the
Use the point-to-point optical transmission device as the left-side connection optical transmission device
Then, each terminal device converts the transmission signal given to the signal input unit into a transmission optical signal suitable for transmission through the optical fiber transmission line, and the transmission optical signal is output to the signal output unit. It has a function to output from the
Connects to the working optical transmitter and standby optical fiber for
And a function to output the optical signal for transmission that has reached the signal input section through the optical fiber transmission line as a received signal from the signal output section.
Active optical receiver and standby optical fiber for connecting to
Standby optical receiver for connecting to the optical fiber, an optical switch inserted between each optical transmitter and each optical receiver and the optical fiber transmission line, and an optical signal for transmission transmitted through the optical fiber transmission line. A failure detector that detects a transmission failure and an optical switch controller that controls the switching of the optical switch based on the detection result of the failure detector are provided so that the failure detector does not detect the transmission failure. Occasionally, the optical signal for transmission output from the optical transmitter is guided to the optical fiber transmission path toward the terminal equipment of the other party, and is transmitted from the terminal equipment of the other party via the optical fiber transmission path. When a failure occurs when the failure detector detects a transmission failure, the transmission optical signal output from the optical transmitter is optically received. Loop back to the machine Such that the second switching state as it is collected by the optical switch controller is configured to perform switching control for the light switch, the fault detecting unit is detected a transmission failure
In case of a known failure, the transmission output from the active optical transmitter
Looping back the optical signal to the standby optical receiver
The optical signal for transmission output from the standby optical transmitter
To be able to loop back to the optical receiver
So the switching control is performed with respect to the optical switch, the specific
In the base station that is the signal source for the
Working optical transmitter of optical transmission equipment or transmission equipment for left side connection
The specific signal given as a transmission signal, a specific signal to the
At the base station, which is the signal termination for the
Output from the working optical receiver of the device or the transmission device for left-side connection.
The received signal that is input is extracted as a termination signal and specified
Right-side connection at the base station that functions as a relay station
Signal output from the current optical receiver of the optical transmission equipment
As the transmission signal to the active optical transmitter of the transmission device for left-side connection.
Output from the current optical receiver of the left side optical transmission device.
Received input signal is transmitted to the right side of the transmission equipment for active system optical transmission
As a transmission signal to all the base stations.
Received signal output from the standby optical receiver of the continuous optical transmission device
Signal to the standby optical transmitter of the transmission device for left side connection
From the standby optical receiver of the optical transmission device for left side connection
Output the received signal to the standby system optical transmission of the transmission device for right side connection
Each group so that it can be given as a transmission signal to the
Intra-station wiring is performed at the ground station.

(2) A second aspect of the present invention is the above-mentioned first aspect.
In the optical transmission network system according to this aspect, when a failure occurs in the optical fiber transmission line, the optical switch is switched to the second switching state in both the first terminal device and the second terminal device. As described above, the optical switch controller in the first terminal device and the optical switch controller in the second terminal device are configured so as to perform a linking operation.

(3) A third aspect of the present invention is the above-mentioned second aspect.
In the optical transmission network system according to the aspect, the optical fiber transmission path includes a first transmission path for transmitting an optical signal from the first terminal station device to the second terminal station device, and a second terminal station device for transmitting the optical signal. A second transmission line for transmitting an optical signal to the terminal device of 1;
When a failure occurs in only one of the transmission lines, the detection result of the failure detector of the terminal device on the receiving end side of the failed transmission line is By using the information to notify the terminal device of the other party, the connection operation at the time of failure is performed.

(4) A fourth aspect of the present invention is the above-mentioned second aspect.
In the optical transmission network system according to this aspect, failure processing to be performed when the failure detector detects a transmission failure is determined in advance, and the first terminal device and the second terminal device have the same failure. By executing the time processing, the connection operation at the time of failure is performed.

[0011]

[0012]

(5) A fifth aspect of the present invention relates to the above-mentioned first aspect.
-In the optical transmission network system according to the fourth aspect, a signal having the first format is transmitted on the intra-station wiring, and a signal having the second format is transmitted on the optical fiber transmission line used as the inter-station wiring. So that each of the optical transmitters and each of the optical receivers perform format conversion so that the data is transmitted.

(6) A sixth aspect of the present invention relates to the above-mentioned first aspect.
In the optical transmission network system according to the fifth aspect, the format of the signal transmitted on the optical fiber transmission line of the right side connection optical transmission device and the signal transmitted on the optical fiber transmission line of the left side connection optical transmission device The format is different.

(7) A seventh aspect of the present invention is based on the above first aspect.
In the optical transmission network system according to the sixth aspect, on the intra-station wiring, there are n types of individual signals transmitted by a plurality of n transmission paths, and on the optical fiber transmission path used as inter-station wiring, Each optical transmitter and each optical receiver are configured to multiplex and restore signals so that it can take the form of a multiplex signal obtained by synthesizing different signals.

[0016]

(8) An eighth aspect of the present invention is based on the above first aspect.
-In the optical transmission network system according to the seventh aspect, in a normal state, a main signal having a high priority which is a transmission target using the active optical fiber and a low priority having a transmission target using the standby optical fiber are low. In order to be able to transmit both the sub-signal and the sub-signal, an add-drop having a first function of adding or extracting a signal and a second function of simply passing the signal to a predetermined base station. The device is arranged, and the received signal output from the standby optical receiver of the right side connection optical transmission device is given as a transmission signal to the standby system optical transmitter of the left side connection transmission device via the add / drop device, and the left side connection is performed. Wiring in the station so that the received signal output from the standby optical receiver of the optical transmission device for use in transmission can be given as a transmission signal to the standby optical transmitter of the transmission device for right side connection via the add / drop device. During normal times, the sub-signal is added or extracted using the first function of the add / drop device, and the transmission of the main signal using the working optical fiber and the transmission of the sub signal using the standby optical fiber are performed. When a failure occurs, the second function of the add / drop device is used to transmit the main signal using the standby optical fiber.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described based on illustrated embodiments.

§1. Optical transmission using general node equipment
Network system The present invention basically relates to an optical transmission network system that secures high reliability by utilizing a self-relief ring using an optical switch. Therefore, here, an example in which this self-relief ring is configured using a node device that has been generally used in the past will be described as a reference example, and the problem will be pointed out.

FIG. 1 is a block diagram showing such a reference example. In this example, base stations are provided at four points A, B, C, and D (portions surrounded by thin chain lines), and each base station has node devices a, b, and c, respectively. , D (a portion surrounded by a thin solid line rectangle) are arranged. In addition, these four points A, B, C, D
A ring-shaped route that connects each base station installed in a ring is defined, and along this ring-shaped route, the working optical fiber used in normal times (indicated by a thick solid line) and the standby system optical used when a failure occurs A fiber (indicated by a thick broken line) is provided. As the working optical fiber and the standby optical fiber, a clockwise fiber for clockwise signal transmission and a counterclockwise fiber for counterclockwise signal transmission are used along the annular path. That is, the working optical fiber F1 located on the outermost side of the annular path is a clockwise fiber, the working optical fiber F2 located second from the outside is a counterclockwise fiber, and the standby optical fiber F3 located third from the outside is The clockwise fiber and the spare optical fiber F4 located on the innermost side are counterclockwise fibers. In the network system having the self-relief ring, the working optical fiber and the standby optical fiber are doubly arranged along the annular path as described above, and signal transmission can be performed both clockwise and counterclockwise. become.

The node device provided in each base station transmits / receives a signal to / from a right adjacent base station adjacent in the clockwise direction and a terminal device to / from a left adjacent base station adjacent in the counterclockwise direction. It is equipped with a terminal device. Each of these terminal devices includes an active optical transmitter (indicated by a black square), an active optical receiver (indicated by an open square),
Standby optical transmitter (indicated by a black square with white diagonal lines), standby optical receiver (indicated by a white square with black diagonal lines), optical switch (indicated by a rounded rectangle, the thin solid line inside indicates the switch Showing the connection state). For example, the left half constituent element shown in the node device a of the base station provided at the point A is a terminal station device that transmits / receives a signal to / from the left adjacent base station (base station provided at the point B). , The right half component is a terminal station device that transmits / receives signals to / from the right adjacent base station (base station provided at the point D).

Here, a simple example is shown in which the base stations at points A and C function as a signal source and a signal terminal, and the base stations at points B and D function as a relay station. That is, in the base station at the point A, a signal source device Ain (shown by a black circle) for generating a signal to be transmitted,
The signal terminating device Aout at which the received signal finally arrives
Similarly, in the base station at the point C, a signal source device Cin (indicated by a black circle) for generating a signal to be transmitted and a signal terminating device to which the received signal finally reaches. Cout is placed. Signal source device Ain at point A
The specific signal generated at the signal source device Cin at the point C is transmitted through the optical transmission network system to the signal terminating device Cout at the point C. Conversely, the specific signal generated at the signal source device Cin at the point C is transmitted through the optical transmission network system. Via network system,
It will be transmitted to the signal terminating device Aout at the point A.

In normal times when there is no abnormality in the optical fibers F1 to F4, the optical switches in all the node devices a to d are
As shown in the figure, the optical transmitter and the optical fiber are connected to each other. In such normal times, signal transmission between points A and C is performed via the following routes. First, the signal generated by the signal source Ain at the point A is converted into a transmission optical signal suitable for transmission through the optical fiber transmission line in the working optical transmitter on the left side of the node device a, and the optical switch Working optical fiber F via SWa2
It is guided to one end of No. 2 and is transmitted to the node device b at the point B via the optical fiber F2 as it is. In the node device b, the signal transmitted on the working optical fiber F2 passes through the optical switch SWb1, the working optical receiver, the working optical transmitter, and the optical switch SWb2 to the node device c at the point C. Toward the working optical fiber F2. In this way, the signal reaching the node device c is received by the working optical receiver via the optical switch SWc1 and is guided to the signal terminating device Cout.

On the other hand, the signal generated by the signal source Cin at the point C is converted into a transmission optical signal suitable for transmission through the optical fiber transmission line in the working optical transmitter on the left side of the node device c. , Is guided to one end of the working optical fiber F1 via the optical switch SWc1, and is directly guided to the optical fiber F1.
Is transmitted to the node device b at the point B via. In the node device b, the signal transmitted on the working optical fiber F1 passes through the optical switch SWb2, the working optical receiver, the working optical transmitter, and the optical switch SWb1 to the node device a at the point A. Toward the working optical fiber F1. In this way, the signal that has reached the node device a is received by the working optical receiver via the optical switch SWa2 and is guided to the signal terminating device Aout.

As described above, signal transmission during normal times between the points A and C is carried out at the point B as a relay station. However, if some trouble occurs in the optical fiber between the points A and B, the signal transmission through the above-mentioned route will be hindered. In an optical transmission network system with a self-relief ring, in such a case,
By switching the faulty route to the detour route, the fault can be recovered.

FIG. 2 shows the occurrence of such a failure.
It is a block diagram which shows the state which performed restoration. As shown in the figure, a fault X has occurred in the optical fiber between points A and B, and signal transmission through this optical fiber cannot be performed. In this case, failure recovery can be performed by switching the optical switch SWa2 in the node device a and the optical switch SWb1 in the node device b located at both ends of the failed optical fiber as shown in the figure. Optical switch SWa2 and optical switch SW shown in FIG.
The switching state of b1 is such that the transmission optical signal output from the optical transmitter is looped back to the optical receiver, and more specifically, the transmission optical signal output from the active optical transmitter is used. Is looped back to the standby optical receiver, and the transmission optical signal output from the standby optical transmitter is looped back to the active optical receiver.

By performing such a loopback, signal transmission between points A and C can be performed through the following paths even in the event of a failure. First, the signal generated from the signal source Ain at the point A enters the optical switch SWa2 from the working optical transmitter on the left side of the node device a, and the traveling direction is reversed by loopback to be transmitted to the standby optical receiver. Then, it is guided to one end of the spare optical fiber F3 through the spare optical transmitter and the optical switch Swa1 on the right side of the node device a, and passes through the relay station at the point D via the optical fiber F3 as it is. It passes through the relay station at the point C (the node device c functions as a relay station with respect to the route of the protection optical fiber F3) and reaches the node device b at the point B. Furthermore, in the node device b, the optical switch SWb2, the standby optical receiver, and the standby optical transmitter are passed through the optical switch SWb2.
The traveling direction is reversed due to the loop back of b1, and the working system optical receiver, the working system optical transmitter, the optical switch SWb2, the working system optical fiber F2, and the node device c at the point C are returned. The signal is led to the signal terminating device Cout via the optical switch SWc1 and the working optical receiver.

On the other hand, the signal generated by the signal source Cin at the point C is converted into a transmission optical signal suitable for transmission through the optical fiber transmission line in the working optical transmitter on the left side of the node device c. , Is guided to one end of the working optical fiber F1 via the optical switch SWc1, and is directly guided to the optical fiber F1.
Is transmitted to the node device b at the point B via. In the node device b, the traveling direction of the signal transmitted on the working optical fiber F1 is reversed by the loopback of the optical switch SWb1 after passing through the optical switch SWb2, the working optical receiver and the working optical transmitter. , The standby optical receiver, the standby optical transmitter, the optical switch SWb2, the standby optical fiber F4, and the relay station at the point C (with respect to the route of the standby optical fiber F4, the node device c is a relay station). Functioning as) and further through the relay station at point D to reach the node device a at point A. Furthermore, the node device a
Then, the traveling direction is reversed by the loopback of the optical switch SWa2 after passing through the optical switch SWa1, the standby optical receiver, and the standby optical transmitter, and is guided to the signal terminating device Aout via the active optical receiver. become.

§2. Node equipment as point-to-point optical transmission equipment
Basic Concept of Conversion As described above, in §1, an example in which an optical transmission network system using a self-relief ring using an optical switch is realized by using a node device that has been generally used in the past has been shown. However, if an optical transmission network system is constructed based on the basic idea of installing node devices at each point and connecting these with optical fibers, as already mentioned, there is freedom in designing and expanding the network. The problem is that the degree is severely limited.

For example, in the example described in §1, the node equipment a, which is installed in each base station at the points A, B, C, D,
When b, c, and d are to be procured from different vendors, in reality, they have to face difficult problems.
Specifically, in order to transmit / receive a signal between the point A and the point B, it is necessary to standardize the format of the optical transmission signal transmitted / received by the node devices a and b. Further, as shown in FIG. 2, when a failure X occurs in the optical fiber between the points A and B, on the node device a side, the optical switch SWa2 is switched as shown in the drawing to loop back and the node device b side. Then, it is necessary to switch the optical switch SWb1 as shown in the drawing to loop back, but the node devices a and b
Is a device supplied by a different vendor,
It is difficult to smoothly perform such a switching process. In order to deal with such a problem, it is necessary to procure all node devices from the same vendor, but in constructing an optical transmission network system covering a wide area, all node devices should be procured from the same vendor. Procurement is not realistic.

In this way, when a network is constructed in the conventional way of arranging independent node devices at each point and connecting them with an optical fiber, the degree of freedom in designing and expanding the network is remarkably high. You will be limited. The inventor of the present application has realized that the above-described problem can be solved by changing the conventional idea and replacing the node device with a point-to-point optical transmission device. Figure 3 shows the basic concept.
Also, description will be made with reference to the block diagram of FIG.

FIG. 3 is a block diagram showing a basic model of an optical transmission network system using a node device which has been generally used conventionally. 4 points A, B,
Each of the C and D base stations has node devices a, b, and
c and d are arranged, and each node device has a terminal station device a1 for transmitting / receiving a signal to / from the right adjacent base station.
b1, c1, d1 and terminal station devices a2, b2, c2, d2 for transmitting and receiving signals to and from the left adjacent base station are provided. Here, an optical fiber Fα is connected between the terminal devices a2 and b1, an optical fiber Fβ is connected between the terminal devices b2 and c1, and an optical fiber Fγ is connected between the terminal devices c2 and d1. An optical fiber Fδ is connected between the terminal devices d2 and a1. In the case of a long distance optical transmission network system, points A, B, C and D are, for example, Tokyo,
It is common to be several hundred kilometers away from each other, as in cities such as Niigata, Osaka, and Nagoya. For this reason, the idea of "installing each node device a, b, c, d having an independent control function for each city A, B, C, D" is a very natural idea. The optical fibers Fα, F are connected between the node devices a, b, c, d.
The idea of "connecting through a connecting path of β, Fγ, Fδ" is also a very natural idea.

On the other hand, FIG. 4 is a block diagram showing a basic model of an optical transmission network system using the point-to-point optical transmission apparatus according to the present invention. 4 points A, B,
The point that each base station is provided in C and D to transmit and receive signals is the same as the basic model in FIG. However, instead of installing node devices at each point,
The basic idea is greatly different in that the point-to-point optical transmission device having an independent control function is installed along the connection path between the points. In the illustrated example, the point-to-point optical transmission apparatus PP is provided along the optical fiber Fα.
(Α) is installed, the point-to-point optical transmission apparatus PP (β) is installed along the optical fiber Fβ, the point-to-point optical transmission apparatus PP (γ) is installed along the optical fiber Fγ, and the optical fiber Fδ A point-to-point optical transmission device PP (δ) is installed along the line. Here, the point-to-point optical transmission apparatus PP (α) is
The end point devices α1 and α2 are provided at both ends of the point-to-point optical transmission device PP (β), and the end point devices β1 and β2 are provided at both ends of the point-to-point optical transmission device PP (γ). And the terminal devices γ1 and γ2, and the point-to-point optical transmission device PP (δ)
Is a device that has terminal station devices δ1 and δ2 at both ends thereof, and has a function of bidirectionally communicating between both terminal device.

The hatched portions in FIG. 3 are the node devices a, b, c and d, respectively, while the hatched portions in FIG. 4 are the point-to-point optical transmission devices. PP (α), PP (β), P
P (γ) and PP (δ). As described above, both the node device and the point-to-point optical transmission device can be provided as a single device by a specific vendor, but there is a large difference in the functions of the components constituting the network system. . For example, the node device a shown in FIG. 3 is installed in the base station at the point A, and the optical fiber F
It plays a role of a relay device that relays a signal transmitted on α and a signal transmitted on the optical fiber Fδ. On the other hand, the point-to-point optical transmission apparatus Fα shown in FIG.
Is installed across the base station at the point A and the base station at the point B, transmits the signal given to the terminal device α1 to the terminal device α2, and conversely, is given to the terminal device α2. It plays the role of a transmission device that transmits the generated signal to the terminal device α1.

The point to be noted here is that in the node device a shown in FIG. 3, the terminal devices a1 and a2 located at the same point are terminal devices within the same device, whereas the two points shown in FIG. In the inter-optical transmission apparatus PP (α), the terminal station devices α1 and α2 at different points are terminal station devices within the same device. In other words, in the case of the node device a, the terminal devices a1 and a2 located at the same point have a common control device (even if they are physically separated, mutual information communication is performed between them and a linking operation is performed. In general, a point-to-point optical transmission device PP (α) is a terminal device at a different point. α1 and α2 have a common control device (even if they are physically separated, they have a control device designed to perform mutual communication and mutual communication), and are generally from the same vendor. It is a device related to design and manufacturing. From this, it can be easily understood that the point-to-point optical transmission device is more advantageous than the node device when used in the optical transmission network system using the self-relief ring.

That is, in the case of transmitting and receiving a signal between the points A and B via the optical fiber Fα, in the system shown in FIG. 3, between the terminal station device a2 and the terminal station device b1 (in other words, While it is necessary to ensure the consistency of the format of the optical transmission signal between different node devices, in the method shown in FIG. 4, between the terminal device α1 and the terminal device α2 (in other words, in other words). , Within the same point-to-point optical transmission device), it is sufficient to ensure the consistency of the optical transmission signal format. Further, in the case of performing a recovery process when a failure occurs in the optical fiber Fα, in the system shown in FIG. 3, the terminal station device a2 and the terminal station device b are
1 (in other words, between different node devices), it is necessary to ensure the consistency of the process of bypassing the transmission path, whereas in the method shown in FIG. It suffices to secure the consistency of the processing for bypassing the transmission path with the station apparatus α2 (in other words, within the same point-to-point optical transmission apparatus).

The system shown in FIG. 4 is "between cities AB, BC
Point-to-point optical transmission equipment PP (α), PP (β), PP (γ), PP
(Δ) is installed and these point-to-point optical transmission devices are connected to each other within each base station ”, and a concept far from the conventional common sense is adopted. However, it is very convenient to use in an optical transmission network system using a self-relief ring. In FIG. 3, terminal station devices a1 and a in the node device a
Even if 2 is a device designed and manufactured by the same vendor, no great merit can be obtained. On the other hand, in FIG. 4, the point-to-point optical transmission apparatus PP
If the terminal devices α1 and α2 in (α) are devices designed and manufactured by the same vendor, as described above, a great advantage can be obtained in performing signal transmission processing and failure recovery processing. In fact, in the system shown in FIG. 4, even if the point-to-point optical transmission devices PP (α) and PP (δ) are provided by different vendors, no big problem occurs. In this case, the pair of terminal equipments α1 and δ2 used in the same base station provided at the point A are manufactured by different vendors, but on the intra-station wiring connecting the terminal equipments α1 and δ2. Then, if it is possible to exchange signals having a common format, the format of the optical transmission signal on the optical fiber Fα and the optical fiber Fα
Even if the format of the optical transmission signal on δ is different, no problem occurs.

In this way, if the optical transmission network system is constructed using the point-to-point optical transmission equipment, even if the individual point-to-point optical transmission equipment is procured from different vendors, no major trouble will occur. , It will be possible to increase the flexibility of network design and expansion. Of course, when a pair of point-to-point optical transmission devices used in the same base station are procured from different vendors, it is necessary to standardize the signal transmission method on the intra-station wiring in the base station. For example, in the example of FIG. 4, if the point-to-point optical transmission apparatuses PP (α) and PP (δ) are provided by different vendors, the terminal station apparatus α1 in the base station provided at the point A is shown. It is necessary to standardize the signal transmission method on the intra-station wiring between the terminal device δ2 and the terminal device δ2 between both vendors. However, the standardization of the format of the optical transmission signal on such intra-station wiring (generally, the length is about several hundred meters) is based on the inter-station wiring (generally, the length is several tens of meters).
This is extremely easy as compared with the standardization of the format of the optical transmission signal above 0 km to several hundreds km. Generally, in signal transmission between long distance stations, an optical signal transmission wavelength, an optical code format (for example, RZ, NRZ, etc.), a multiplexing method (for example, WDM, TDM, etc.) described later, an error correction code format. It is necessary to make various arrangements such as a chromatic dispersion compensation method for an optical fiber, and it is very difficult to standardize such various matters. On the other hand, the standardization of the signal transmission method on the intra-station wiring, which is a relatively short distance, does not cause so much difficulty.

§3. Optical transmission using point-to-point optical transmission equipment
Network System Here, an example in which an optical transmission network system having a self-relief ring is configured using a point-to-point optical transmission device based on the basic idea described in §2 will be shown. FIG. 5 is a block diagram showing such an embodiment. In this embodiment, base stations are provided at four points A, B, C, and D (portions surrounded by thin chain lines), and two base stations are provided so as to straddle each adjacent base station. Point-to-point optical transmission equipment PP (α), PP (β), PP (γ), PP
(Δ) is arranged (the part surrounded by a thin solid line).
Similar to the reference example shown in FIG. 1, these four points A, B,
A ring-shaped path connecting each of the base stations provided in C and D in a ring shape is defined. Along with this ring-shaped path, a working optical fiber used in normal times (indicated by a thick solid line) and a failure-use optical fiber are used. A spare optical fiber (indicated by a thick broken line) is provided. As the working optical fiber and the standby optical fiber, a clockwise fiber for clockwise signal transmission and a counterclockwise fiber for counterclockwise signal transmission are used along the annular path. That is, the working optical fiber F1 located on the outermost side of the annular path is a clockwise fiber, and the working optical fiber F located second from the outer side.
Reference numeral 2 is a counterclockwise fiber, the standby optical fiber F3 located third from the outside is a clockwise fiber, and the backup optical fiber F4 located at the innermost side is a counterclockwise fiber.
The configuration relating to such a self-relief ring is similar to that of the reference example shown in FIG. 1, but the control device that functions when a failure occurs has a major feature.

Point-to-point optical transmission apparatus PP (α), PP
(Β), PP (γ), PP (δ) are at both ends of the terminal devices α1 and α2, β1 and β2, γ1 and γ, respectively.
2, δ1 and δ2, and the above-mentioned four optical fibers F1 to F4 are connected between the respective terminal equipments. Each terminal device includes an active optical transmitter, an active optical receiver,
It has a standby optical transmitter, a standby optical receiver, and an optical switch, and further has a failure detector and an optical switch controller (both are not shown in FIG. 5) described later. .
In an actual device, an optical amplifier needs to be inserted at a predetermined position, but since it is not an essential constituent element here, the description of the optical amplifier is omitted.

Each optical transmitter has a signal output section on one side facing the optical switch and a signal input section on the other side.
The optical signal for intra-station wiring given to the signal input section as a transmission signal is converted into a transmission optical signal suitable for transmission through the optical fiber transmission line, and this transmission optical signal is output from the signal output section. Have a function. Further, each optical receiver has a signal input section on one side facing the optical switch and a signal output section on the other side, and transmits the optical signal for transmission reaching the signal input section via the optical fiber transmission line, It has a function of converting into an optical signal for intra-station wiring and outputting the optical signal for intra-station wiring from the signal output unit as a reception signal. On the other hand, the optical switch is a switch that is inserted between each optical transmitter and the optical fiber and between each optical receiver and the optical fiber. It has a function to loop back in case of failure.

With such a configuration, the optical signal for transmission is transmitted through the optical fiber between the terminal equipments located at both ends of the same point-to-point optical transmission equipment, and the pair of optical signals for transmission within the same base station is transmitted. The optical signal for intra-station wiring is transmitted via the intra-station wiring between the terminal station devices located at the respective ends of the point-to-point optical transmission device. For example, between the terminal devices α1 and α2 located at both ends of the point-to-point optical transmission device PP (α), an optical signal for transmission is transmitted via an optical fiber of a relatively long distance, but at the point B. Terminal device α2 in the base station
Between β1, the optical signal for intra-station wiring is transmitted through the relatively short-distance optical fiber for intra-station wiring. In the case of the present embodiment, the distance between the terminal equipments (for example, the terminal equipments α1 and α2) located at both ends of the same point-to-point optical transmission equipment is several tens of kilometers to several hundreds of kilometers, while in the same base station. The distance (intra-station wiring distance) between the terminal equipments (for example, the terminal equipments α2 and β1) located at the ends of the pair of point-to-point optical transmission equipments is about several hundred meters at most. Therefore, in this embodiment, the optical signal for intra-station wiring is 1.3
A signal having a wavelength in the μm band is used, and a signal having a wavelength in the 1.55 μm band suitable for long-distance transmission is used as the optical signal for transmission. Therefore, each optical transmitter and each optical receiver have a function of performing mutual conversion between a signal having a wavelength of 1.3 μm band and a signal having a wavelength of 1.55 μm band. If necessary, each function such as a wavelength division multiplexing function, a time division multiplexing function, and an error correction code addition function is added to the optical transmitter, and various functions corresponding to these respective functions are added to the optical receiver. You may make it add a function.

FIG. 6A shows a point-to-point optical transmission device PP.
It is a block diagram which shows the detailed structure of ((alpha)). As described above, the point-to-point optical transmission device PP (α) is composed of the optical fiber transmission lines F1 to F4 and the terminal devices α1 and α2 arranged at both ends thereof, and each terminal device α1, α
Reference numeral 2 denotes an active optical transmitter, an active optical receiver, a standby optical transmitter, a standby optical receiver, and optical switches SWα1 and SWα.
2. Equipped with a failure detector and an optical switch controller SD. The fault detector (indicated by a small rectangle in the figure) is a device having a function of detecting a transmission fault of a transmission optical signal at the receiving end of each optical fiber. In this embodiment, the optical power is monitored. A device with functions is used as a fault detector. When a failure such as cutting of the optical fiber occurs, the optical power at the receiving end is attenuated, so that the failure detector can detect the failure based on the attenuation of the optical power. The failure detector may be provided not only at the receiving end but also in the middle of the optical fiber transmission line.

In each terminal device, when a failure is detected by the failure detector, the optical switch controller SD controls the switching of the optical switch based on the detection result. Specifically, an alarm signal is transmitted from the failure detector that has detected the failure to the optical switch controller SD, and the optical switch controller SD performs control to switch the optical switch based on the alarm signal. .

The basic policy of the optical switch switching control by the optical switch controller SD is the same as in the case of the reference example described in §1. That is, during normal times when the failure detector does not detect a transmission failure, the optical signal for transmission output from the optical transmitter is guided to the other end station device to the optical fiber transmission path, and The first switching state is formed so that the transmission optical signal transmitted from the terminal device of the other party via the can be guided to the optical receiver, and when the failure detector detects the transmission failure, Appropriate switching control is performed so that a second switching state in which the transmission optical signal output from the optical transmitter can be looped back to the optical receiver is formed. More specifically, in a normal state, the active optical transceiver is connected to the active optical fiber, and the standby optical transceiver is connected to the standby optical fiber. The transmission optical signal output from the transmitter is looped back to the standby optical receiver in the same terminal equipment, and the transmission optical signal output from the standby optical transmitter is used in the same terminal equipment. The switching control for each optical switch may be performed so that the system can be looped back to the optical receiver.

Note that the switching control of the optical switch at the time of a failure must be performed by linking a pair of terminal station devices located at both ends of the failed optical fiber. Even if the switching control is performed only in either one of the terminal devices, a normal detour route cannot be secured. For example, when a failure occurs in the optical fiber between the points A and B, the switching control for the optical switch SWα1 in the terminal device α1 and the optical switch S in the terminal device α2 are performed.
The switching control for Wα2 must be performed in tandem.

Here, a concrete method for performing such a linked operation at the time of failure will be described. First, point A,
A method will be described in the case where a failure occurs in only one of the upstream and downstream working optical fiber transmission lines connecting between Bs. In this case, by transmitting the detection result of the fault detector of the terminal device on the receiving end side of the faulty transmission line to the other end device by using the transmission line in which no fault has occurred, It is possible to perform a linked operation. For example, consider a case where a fault X occurs only in the optical fiber F1 as shown in FIG. 6 (b). In this case, in the terminal device α1 on the receiving end side of the optical fiber F1, the optical fiber F1
The fault can be detected by the fault detector for No. 1. Therefore, with the fault detector for the optical fiber F1,
An alarm signal is sent to the optical switch controller SD in the terminal device α1. The optical switch controller SD that has received the alarm signal drives the optical switch SWα1 in the same terminal device to perform switching for loopback, and also to perform an alarm signal via the optical fiber F2 in which no failure has occurred. Is also sent to the optical switch controller SD in the other terminal device α2.
The alternate long and short dash line in FIG. 6B shows the route of this alarm signal. The optical switch controller SD in the terminal device α2 that receives this alarm signal also drives the optical switch SWα2 and performs switching for loopback. In this way, since the optical switch controllers SD in both the terminal devices α1 and α2 can recognize the occurrence of a failure, the switching control of the optical switches can be linked and performed.

Next, a method in the case where a failure occurs in all the optical fiber transmission lines between the points A and B will be described. For example, consider a case where a fault X occurs in the entire optical fibers F1 to F4, as shown in FIG. 6 (c). In this case, the terminal device α1 on the receiving end side of the optical fiber F1 can detect a failure by the failure detector for the optical fiber F1. Similarly, the terminal device α2 on the receiving end side of the optical fiber F2
However, the fault can be detected by the fault detector for the optical fiber F2. Therefore, each terminal device α
An alarm signal is sent from each failure detector to the optical switch controllers SD in 1 and α2. With this alarm signal, the optical switch controllers SD in both the terminal devices α1 and α2 can recognize the occurrence of a failure and drive the respective optical switches to loop back, thus linking the switching control of the optical switches. Can be done by

After all, each failure detector sends a warning signal to its own optical switch controller when it detects a failure and also sends the same warning signal to the other party's optical switch controller (see FIG. If there is a failure in the entire optical fiber transmission line, as in 6 (c), the alarm signal to the other party will not actually serve its purpose), but the optical switch controller will When a signal is received, a process at the time of failure of performing switching control of the optical switch so that the failure transmission path can be bypassed is set in advance, and both end station devices α1 and α
In step 2, if the same process at the time of failure is executed, the linking operation of both can be performed at the time of failure.

Now, referring again to FIG. 5, let us consider the normal operation and the failure operation of the optical transmission network system according to this embodiment. Here again, a simple example will be given in which the base stations at points A and C function as a signal source and a signal terminal, and the base stations at points B and D function as a relay station. That is, point A
The signal source device Ain for generating the signal to be transmitted and the signal terminating device Aout to which the received signal finally arrives are arranged in the base station of the above. Similarly, in the base station of the point C, A signal source device Cin that generates a signal to be transmitted and a signal terminating device Cout that the received signal finally reaches are arranged. Signal source device Ain at point A
The specific signal generated at the signal source device Cin at the point C is transmitted through the optical transmission network system to the signal terminating device Cout at the point C. Conversely, the specific signal generated at the signal source device Cin at the point C is transmitted through the optical transmission network system. Via network system,
It will be transmitted to the signal terminating device Aout at the point A.

In normal times when there is no abnormality in each of the optical fibers F1 to F4, all the optical switches are as shown in the figure.
The optical transceiver and the optical fiber are in a connected state. In such normal times, signal transmission between points A and C is performed via the following routes. First, the signal generated by the signal source Ain at the point A (intra-station wiring optical signal having the wavelength format of 1.3 μm) is transmitted through the optical fiber transmission line in the working optical transmitter in the terminal device α1. Is converted into a signal (optical signal for transmission having a wavelength format of 1.55 μm band) suitable for long-distance transmission via the optical switch SWα1 and the working optical fiber F2 is used.
To the terminal device α2 at the point B as it is. This signal received by the terminal device α2 is once converted into an optical signal for intra-station wiring in the 1.3 μm band by the working optical receiver, and then the working optical transmitter in the terminal device β1. Then, it is converted again into a transmission optical signal in the 1.55 μm band and transmitted to the point C via the active optical fiber F2. This signal received by the terminal device β2 at the point C is converted into an optical signal for intra-station wiring in the 1.3 μm band by the working optical receiver and then guided to the signal terminating device Cout. On the other hand, by the opposite route,
The signal generated by the signal source Cin at the point C is guided to the signal terminating device Aout at the point A.

On the other hand, as shown in FIG. 7, when some kind of failure X occurs in the optical fiber between the points A and B, as described above, the connection operation of the terminal devices α1 and α2 causes the optical transmission. The switches SWα1 and SWα2 are switched as shown in the figure, and the transmission optical signal output from the optical transmitter is looped back to the optical receiver. By performing such loop-back, signal transmission between the points A and C can be performed without trouble via the detour even if there is a failure. This detour is the same as the reference example described in §1, so here, the terminal devices on the route will be simply listed. First, signal source Ain at point A
The signal generated in 1 is introduced into the standby optical fiber F3 by loopback in the terminal device α1, and the terminal devices δ2, δ
1, γ2, γ1, β2, β1 are transmitted, and the terminal device α2 is transmitted.
It is returned to the working optical fiber F2 by the loop back in and is guided to the signal terminating device Cout via the terminal devices β1 and β2. On the other hand, the signal generated by the signal source Cin at the point C is transmitted from the terminal device β2 to the working optical fiber F1.
Is introduced into the standby optical fiber F4 by loopback in the terminal device α2, transmitted to the terminal devices β1, β2, γ1, γ2, δ1, δ2, and transmitted to the terminal device α1. The loopback in the above will lead to the signal terminating device Aout. The important thing here is
This is that only the control function in PP (α) can be used to recover the fault X that has occurred in the point-to-point optical transmission apparatus PP (α). That is, another point-to-point optical transmission device PP
(Β), PP (γ), and PP (δ) can completely recover from the failure by the control function completely independent of them. For example, focusing on the base station installed at the point A in FIG. 5, the left-side connection optical transmission apparatus PP (α) for performing transmission to the point B.
And the right-side connection optical transmission device PP (δ) for performing transmission to the point D, the two sets of transmission devices are provided. These two sets of transmission devices are independent from each other in failure recovery. It has a function and there is no need to exchange alarm signals with each other. More specifically, as shown in FIG. 6, the optical switch controller SD is provided in the terminal device α1.
Is also provided, and the optical switch controller SD is similarly provided in the terminal device δ2. Here, although the two sets of optical switch controllers SD are provided in the same base station, they are configured to perform their respective functions independently, and mutual information communication is performed between these two optical switch controllers. (For example, exchanging alarm signals),
It is possible to switch the optical switch when a failure occurs. The fact that the transmission devices PP (α) and PP (δ) are procured from different vendors does not cause any problem because such independent functions are secured.

The embodiments shown in FIGS. 5 and 7 are examples in which the base stations at the points A and C serve as the signal source and the signal terminal for the signal to be transmitted. Cin and the signal terminators Aout and Cout are provided only in these base stations, and the base stations B and D merely function as relay stations, but the signal source and the signal terminator are provided in any base station. be able to. Also, in practice, as described in §4, the signals transmitted via each optical fiber can be multiplexed. When signals are multiplexed in this way, a plurality of n individual signals are combined as multiplexed signals and then transmitted on the optical fiber. Therefore, the signal source and signal termination are 1
Each individual signal will be different, the source of the first individual signal is at point A, the source of the second individual signal is at point B, and so on. The base station at a point functions as a signal source or a terminal station for some individual signals, but functions as a relay station for other individual signals.

Even if such a form is adopted,
Regarding the in-station wiring of the working system in each base station, attention is paid to individual signals, and at the base station (for example, the base station at point A in FIG. 5) that is a signal source for a specific signal, right-side connection optical transmission is performed. The specific signal is given as a transmission signal to the working optical transmitter of the device (PP (δ)) or the transmission device for left side connection (PP (α)), and the base station (eg, At the base station at point C in FIG. 5, the reception signal output from the working optical receiver of the right-side connection optical transmission apparatus (PP (β)) or the left-side connection transmission apparatus (PP (γ)) is used as a termination signal. As a relay station for a specific signal (for example, FIG. 5).
At the base station at point D), the right side optical transmission device (PP)
The received signal output from the working optical receiver of (γ)) is given as a transmission signal to the working optical transmitter of the left side connection transmission apparatus (PP (δ)), and the left side connection optical transmission apparatus (PP
Wiring may be provided so that the reception signal output from the active optical receiver of (δ)) can be given as a transmission signal to the active optical transmitter of the right side connection transmission device (PP (γ)). In addition, regarding the intra-station wiring of the standby system in each base station, for all base stations, the received signal output from the standby system optical receiver of the right side connection optical transmission device is input to the standby system optical transmitter of the left side connection transmission device. Wiring as a transmission signal, and the reception signal output from the standby optical receiver of the left-side connection optical transmission device can be given to the standby optical transmitter of the right-side connection transmission device as a transmission signal. Good.

§4. Embodiments for Transmitting Multiplexed Signals Generally, in an optical transmission network system, signals transmitted via each optical fiber can be multiplexed. §
In the optical transmission network system described in Section 3, when performing such multiplexed transmission, it takes the form of n individual signals transmitted by a plurality of n transmission lines on the intra-station wiring, and is used as inter-station wiring. To allow each optical transmitter and each optical receiver to have a function of multiplexing and recovering signals so that it can take the form of a multiplexed signal obtained by combining the n kinds of signals on the optical fiber transmission line. You can do this.

FIG. 8 shows a modification in which the function shown in FIG. 5 is further added to the embodiment shown in FIG. Each optical transmitter has a wavelength division multiplexer (Wavelength Division Mult).
iplex) is added, and each optical receiver has a function to restore it. here,
The optical transmitter / receiver having such an additional function will be referred to as a WDM optical transmitter and a WDM optical receiver, respectively, taking the acronyms of Wavelength Division Multiplex.

The illustrated example shows an example in which four types of individual signals are multiplexed and transmitted. That is, the transmission optical signal transmitted through one optical fiber is a signal in which four types of individual signals are multiplexed, and in the station, these individual signals are each separated into one intra-station wiring. . For example, in the base station at the point A, in the intra-station wiring that connects the terminal device α1 and the terminal device δ2, each individual signal is assigned to one transmission path, but the WDM optical transmitter It has a function of performing a process of multiplexing each individual signal given from the four intra-station wiring transmission lines and transmitting the multiplexed signal to one optical fiber. Conversely, WDM
The optical receiver has a function of restoring a multiplexed signal transmitted via one optical fiber, extracting four individual signals, and outputting the four individual signals to four intra-station wiring transmission lines.
In this way, in the intra-station wiring, demultiplexing is performed and each individual signal is caused to flow in a different transmission line. That is, in each base station, the signal from the signal source device is transmitted as an arbitrary individual signal. This is so that any individual signal can be taken into the signal terminating device.

In order to correctly transmit each individual signal at the time of failure, the transmission path for a specific individual signal should form a logically closed loop on the ring path of the backup system. In addition, it is necessary to consider the intra-station wiring at each base station.

FIG. 9 shows an embodiment in which an add drop device ADM (Add Drop Module) is further added to the embodiment shown in FIG. In the optical transmission network system according to this embodiment, in normal times, a main signal having a high priority which is a transmission target using the working optical fiber and a sub signal having a low priority which is a transmission target using the standby optical fiber are used. Both signals of and can be transmitted. In the embodiments described so far, the spare optical fiber is used only in the event of a failure, and is not used in normal times. The embodiment shown in FIG. 9 is intended for effective use of the standby optical fiber in normal times. That is, in the normal state, the main signal having a high priority is transmitted through the working optical fiber, which is similar to the above-described embodiments, but at the same time, the sub-signal having a low priority is transmitted to the standby system. It will be transmitted via an optical fiber. However, at the time of a failure, the transmission of this sub-signal is stopped, and the backup optical fiber is used as a bypass for the main signal, as in the previous embodiments.

The add / drop device ADM is an additional component for enabling the transmission of such a sub-signal, and has a first function for adding or extracting a signal and a second function for simply passing the signal. Has a function. As shown in the figure, this add / drop device ADM is arranged in each base station, and is output from the standby optical receiver of the right side optical transmission device (for example, PP (δ) in the case of the base station at point A). The received signal is transmitted via the add / drop device ADM to the left side connection transmission device (for example, in the case of the base station at the point A, P
P (α)) as a transmission signal to the standby system optical transmitter, and the reception signal output from the standby system optical receiver of the left side connection optical transmission device is transmitted through the add / drop device ADM to the right side connection transmission device. Intra-station wiring is performed so that it can be given as a transmission signal to the standby optical transmitter.

In this way, during normal times, the first function of the add / drop device ADM is used to add or extract a sub-signal, and the main signal is transmitted using the working optical fiber, and the standby optical fiber is used. It is possible to carry out the transmission of the auxiliary signal. For example, if a sub-signal with a low priority is added to the add / drop device ADM at the point A and this sub-signal is taken out from the add / drop device ADM at the point C, the sub-signal with a low priority is completely separated from the transmission of the main signal. A signal can be transmitted from point A to point C (the add / drop devices at points B and D have a second function to simply pass this sub-signal). Then, at the time of failure, if all the add / drop devices ADM are switched so as to execute the second function, the detour transmission of the main signal using the standby optical fiber is performed, and no trouble occurs.

[0062]

As described above , according to the present invention, an optical transmission network system is constructed using a point- to- point optical transmission device.
By doing so , it becomes possible to provide an optical transmission network system having a high degree of freedom in design and expansion and high reliability.

[Brief description of drawings]

FIG. 1 is a block diagram of a reference example in which an optical transmission network system serving as a self-relief ring is configured by using a general node device.

FIG. 2 is a block diagram showing an operation when a failure occurs in the optical transmission network system shown in FIG.

FIG. 3 is a block diagram showing a basic model of an optical transmission network system configured by using node devices.

FIG. 4 is a block diagram showing a basic model of an optical transmission network system configured using a point-to-point optical transmission device.

FIG. 5 is a block diagram showing a configuration of an optical transmission network system according to an embodiment of the present invention.

6 is a block diagram showing a detailed configuration and operation of a point-to-point optical transmission device which constitutes the optical transmission network system shown in FIG.

7 is a block diagram showing an operation when a failure occurs in the optical transmission network system shown in FIG.

8 is a block diagram of a system in which a signal multiplexing function is further added to the optical transmission network system shown in FIG.

FIG. 9 is a block diagram of a system in which a sub-signal simultaneous transmission function of low priority is further added to the optical transmission network system shown in FIG.

[Explanation of symbols]

A, B, C, D ... Point a, b, c, d ... Node device a1, a2, b1, b2, c1, c2, d1, d2 ... Terminal device Ain, Cin ... Signal source device Aout, Cout ... Signal Termination device ADM ... Add / drop devices F1 to F4 ... Optical fibers Fα to Fδ ... Optical fibers PP (α) to PP (δ) ... Point-to-point optical transmission device SD ... Optical switch controller SWxx ... Optical switch X ... Fault α1, α2, β1, β2, γ1, γ2, δ1, δ2 ... Terminal device

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-1-141424 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04L 12/437

Claims (8)

(57) [Claims] 1. A base station is provided at each of a plurality of points,
A ring route that connects the base stations in a ring shape is defined, and this ring
Working optical fibers and obstacles for normal use along the route
A spare optical fiber used at the time is installed, and each base station
About the right adjacent group that is adjacent in the clockwise direction of the ring route
Define the left-hand neighbor base station adjacent to the ground station in the counterclockwise direction.
The active system to both the left and right adjacent base stations.
Whether using optical fiber or standby optical fiber
Optical transmission network configured to send and receive optical signals
In the system, a first terminal station device installed at a first point, a second terminal station device installed at a second point, and an optical fiber transmission line connecting these terminal station devices, With the first point and the second
Two places with the function of bidirectional communication with two points
The point-to-point optical transmission device is prepared, and in order to connect each base station and its right adjacent base station,
Use point-to-point optical transmission device as right-side connection optical transmission device
In order to connect each base station with the base station on its left side
The point-to-point optical transmission device as an optical transmission device for left side connection
Utilizing each of the terminal devices , the transmission signal given to the signal input unit is converted into a transmission optical signal suitable for transmission through the optical fiber transmission line, and the transmission optical signal is converted. Has a function to output from the signal output section ,
Working optical transmitter and standby optical fiber for connection
A standby optical transmitter for connection to the optical fiber and a transmission optical signal that has reached the signal input unit via the optical fiber transmission line are output from the signal output unit as a reception signal.
A working system that has functions and is used to connect to the working system optical fiber
Optical receiver and spare system Spare for connecting to optical fiber
System optical receiver, an optical switch inserted between each optical transmitter and each optical receiver and the optical fiber transmission line, and a transmission failure of a transmission optical signal transmitted through the optical fiber transmission line A fault detector to detect, and based on the detection result of the fault detector, an optical switch controller that performs control to switch the optical switch is provided, and in the normal time when the fault detector does not detect a transmission fault, The optical signal for transmission output from the optical transmitter is guided to the optical fiber transmission line toward the terminal device of the other party, and transmitted from the terminal device of the other party through the optical fiber transmission line. In the first switching state in which a transmission optical signal can be guided to the optical receiver, and when the failure detector detects a transmission failure, the transmission optical signal output from the optical transmitter The light receiving Such that the second switching state such that it can be looped back to the machine, the optical switch controller is configured to perform switching control with respect to the optical switch, in the event of a failure of the fault detection device detects a transmission fault , The above
The transmission optical signal output from the active optical transmitter is saved as the backup.
Loopback to the optical receiver and the standby system
The optical signal for transmission output from the optical transmitter is received by the optical receiver of the current system.
The light so that it can be looped back to the belief
The base station, which is the signal source for a specific signal , controls the switch so that the switch is controlled.
Continued optical transmission equipment or left-side connection transmission equipment for active optical transmission
At the base station that gives the specific signal as a transmission signal to the transmitter and becomes the signal termination for the specific signal, the right side
Optical transmission system for connection or working system optical transmission system for left side connection
Extracts the received signal output from the receiver as a termination signal
However, in the base station that functions as a relay station for a specific signal,
Output from the working optical receiver of the right side optical transmission device
Transmits the received signal to the active optical transmitter of the transmission device for left side connection
Give as a signal and receive the optical signal from the working system of the optical transmission device for left side connection
Received signal output from the machine is currently used by the transmission device for right-side connection
It is given as a transmission signal to the system optical transmitter, and at all base stations, the standby system optical of the right side connection optical transmission device is used.
The received signal output from the receiver is transmitted to the left side transmission device.
It is given as a transmission signal to the standby optical transmitter and the optical signal for left side connection is transmitted.
Right side of the received signal output from the standby optical receiver of the transmitter
Provided as a transmission signal to the standby optical transmitter of the connection transmission device
Intra- station wiring is performed at each base station so that
Optical transmission network system. 2. The optical transmission network system according to claim 1.
In the system, if a failure occurs in the optical fiber transmission line, the optical switch is switched to the second switching state in both the first terminal device and the second terminal device so that the first terminal An optical transmission network system , characterized in that an optical switch controller in the station device and an optical switch controller in the second terminal station device are configured to perform an interlocking operation . 3. The optical transmission network system according to claim 2.
In the system , the optical fiber transmission line includes a first transmission line for transmitting an optical signal from the first terminal device to the second terminal device and an optical fiber from the second terminal device to the first terminal device. A second transmission path for transmitting a signal, and when a failure occurs in only one of the transmission paths, detection by the failure detector of the terminal device on the receiving end side of the failed transmission path An optical transmission network characterized in that the result is transmitted to a partner terminal device using a transmission line in which no fault has occurred so that a linking operation is performed in the event of a fault.
Network system. 4. The optical transmission network system according to claim 2.
In the system , a failure process to be performed when the failure detector detects a transmission failure is determined in advance, and the first terminal device and the second terminal device execute the same failure process. , An optical transmission network characterized by performing a linked operation at the time of failure.
Network system. 5. The optical transmission network system according to any one of claims 1 to 4, wherein a signal having the first format is transmitted on the intra-station wiring, and on the optical fiber transmission line used as inter-station wiring. Is an optical transmission network system in which each optical transmitter and each optical receiver have a function of performing format conversion so that a signal having the second format is transmitted. 6. The optical transmission network system according to any one of claims 1 to 5 , wherein the format of a signal transmitted on the optical fiber transmission line of the right side optical transmission device and the optical transmission of the left side optical transmission device. An optical transmission network system characterized in that the format of a signal transmitted on a fiber transmission line is different. 7. The optical transmission network system according to claim 1 , wherein a plurality of n transmission lines are used for transmission on the intra-station wiring.
Each optical transmitter and each optical receiver so that it can take the form of an individual signal in the form of multiple signals and can take the form of a multiplexed signal in which the above-mentioned n types of signals are combined on the optical fiber transmission line used as the inter-office wiring. An optical transmission network system in which a device has a function of multiplexing and restoring signals. 8. The optical transmission network system according to any one of claims 1 to 7 , wherein during normal operation, a main signal having a high priority to be transmitted using a working optical fiber and a standby optical fiber are used. In order to be able to transmit both the low-priority sub-signal to be transmitted and the low-priority sub-signal, the signal is added to or taken out from a predetermined base station.
And a second function of simply passing a signal are arranged, and a reception signal output from the standby optical receiver of the right side connection optical transmission device is passed through the add / drop device. The transmission signal is given to the standby optical transmitter of the left side connection transmission device as a transmission signal, and the reception signal output from the standby system optical receiver of the left side connection optical transmission device is transmitted via the add / drop device to the right side connection transmission device. Wiring in the station is performed so that it can be given to the standby optical transmitter as a transmission signal, and during normal times, the sub-signal is added or extracted using the first function of the add / drop device, and the active optical fiber is used. In addition to the transmission of the main signal, the auxiliary optical fiber is used to transmit the auxiliary signal. In the event of a failure, the second function of the add / drop device is used to operate the auxiliary optical fiber. An optical transmission network system, wherein the transmission of the use the main signal has to be performed.