JP2001016240A - Optical ring network - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical ring network by which lines are relieved on the occurrence of a fault, eliminating the limit on the number of nodes in a ring can optionally extend nodes and the shortest route can quickly be selected on the occurrence of a fault. SOLUTION: In this optical ring network, three optical fibers F1-F3 interconnect a plurality of node units 1-4 in a form of a ring to configure an optical communication network consisting of three rings. In each of the optical node units 1-4, the connection state between input and output units is switch-controlled depending on the occurrence state of a fault on 1st and 2nd rings, a transmission path of an optical signal bypassing a faulty location is set by using a 3rd ring to execute relief of the lines on the occurrence of a fault.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical ring network in which a plurality of optical nodes are interconnected to form a ring-shaped optical communication network, and more particularly to a line rescue function when a failure occurs on the ring network. The present invention relates to an optical ring network including:

[0002]

2. Description of the Related Art SDH (Synchronous Digital Hierarch)
y) Optical communication systems typified by systems have been required to introduce large-capacity systems with the increase in data traffic and diversification of services as symbolized by the Internet in recent years. However, it is not only a matter of simply increasing the capacity of the system, and the reliability of the service is regarded as important as the capacity is increased.

For example, in an optical communication network of an SDH system, even if one optical fiber is accidentally cut, an optical signal passing through the cut optical fiber is transmitted through a detour route. In recent years, the reliability as a network that does not intermittently become unable to communicate by adoption has become particularly important in recent years.

[0004] In a conventional optical communication network, 2F-BLS is a typical example of an automatic recovery ring type network for protecting traffic when a failure occurs.
R (2-Fiber Bi-directional Line Switched Ring),
4F-BLSR (4-Fiber Bi-directional Line Switch
ed Ring), UPSR (Uni-directional Path Switched)
Ring) and other systems are ANSI (American National)
Standards Institute).

[0005] First, an optical communication network of a conventional 2F-BLSR system will be briefly described. FIG.
FIG. 11 is a diagram illustrating a configuration example of a conventional 2F-BLSR system. However, FIG. 21 shows a case where a ring network is configured by 10G (STM-64).

In FIG. 21, the 2F-BLSR system has a configuration in which optical node devices A to D are connected in a ring shape using two optical fibers. Each optical fiber (line) has its transmission capacity divided into two equal parts, and one is used as a work channel (WK) and the other is used as a protection channel (PTCT). In FIG.
A conceptual diagram in which the capacity in the line is divided is shown. Here, a 10G ring network is assumed, so
The transmission capacity of this optical fiber is 10 Gbit / s,
A transmission capacity of 5 Gbit / s is allocated to each of the work channel and the protection channel.

In the 2F-BLSR system configured as described above, for example, in FIG. 21, when a failure occurs between the optical node devices A and B, a protection channel on the side opposite (outward) to the failure section is used. , The route "B-C-D-
"A" (two-way) bypasses the failure and remedies so as not to affect the existing work channel. At this time, it is the optical node device A and the optical node device B that perform the ring switch that performs the detour operation. Specifically, this ring switch connects two optical fibers located on the opposite side of the faulty section, and transmits an optical signal propagating through a work channel of one optical fiber to a protection channel of the other optical fiber. And the optical signal propagating through the work channel of the other optical fiber is passed through the protection channel of the one optical fiber.

In the above conventional 2F-BLSR system,
Usually, a protection channel is used as an empty channel. Therefore, the maximum transmission capacity of each optical node device is 10 Gb / s, which is the sum of the transmission capacities of the work channels of the two optical fibers. Also, B
In the LSR system configuration, one channel can be used in different spans. Therefore, in the case of a four-node configuration, in the state shown in FIG. 23, a maximum line capacity of 20 Gb / s is required for the entire ring. It is possible to have.

Further, in order to increase the transmission capacity of the conventional 2F-BLSR system, a PCA (Protection Chamber) is used.
A 2F-BLSR system adopting the nnel access) method is also known. This PCA method aims at increasing the transmission capacity in normal times by passing traffic through a protection channel which is normally set as an empty channel. 2F using PCA method
-In the case of the BLSR system, the transmission capacity of each optical node device is a maximum of 20 Gb / s, and the maximum line capacity of the entire ring is 40 Gb / s, which is twice as large as the case where PCA is not set. Capacity can be secured.

Next, an optical communication network of the conventional 4F-BLSR system will be described. FIG. 24 is a diagram illustrating a configuration example of a conventional 4F-BLSR system.

In FIG. 24, the 4F-BLSR system has a configuration in which optical node devices A to D are connected using four optical fibers. As for the four optical fibers, two each for a work channel and a protection channel are provided, and a system for saving traffic by using a work channel optical fiber during normal times and using a protection channel optical fiber when a failure occurs. Configuration.

In the 4F-BLSR configured as described above,
For example, when a failure occurs only in the work channel optical fiber between the optical node devices A and B, as shown in FIG. 25, the optical node devices A and B at both ends of the failure section perform a protection switch by performing a span switch. Save traffic by switching to the channel side. Specifically, this span switch connects an optical signal (data) transmitted through the protection channel optical fiber in the faulty section to a work channel optical fiber on the opposite side (outer side) to the faulty section, and connects both the optical signals (data). The optical signal operates in such a way that the optical signal travels through the protection channel optical fiber in the faulty section.

When a fault occurs in both the work channel and the protection channel between the optical node devices A and B, as shown in FIG. 26, the optical node devices A and B at both ends of the fault section sandwich the fault. The traffic is relieved by performing a ring switch to perform a detour to the opposite side of the failure section.

Next, an optical communication network of a conventional UPSR system will be described. FIG. 27 shows a conventional UPS.
FIG. 1 is a diagram illustrating a configuration example of an R system. In FIG.
The UPSR system connects two or more optical node devices A to D with each other.
In this configuration, one optical fiber is used for a work channel, and the other is used for a protection channel. Normally, a path is set for both the work channel and the protection channel, and the work channel side is selected by a path switch (Path Switch; PSW) in the optical node device (the optical node device C in FIG. 27) that terminates. I do.

In the UPSR system having the above-described configuration, for example, when a failure occurs between the optical node devices A and B, a path is set in the terminal optical node device C in a direction opposite to the work channel side. The selected protection channel side is selected by the PSW to rescue traffic.

[0016]

However, the above-mentioned conventional optical communication network has the following problems.

In the 2F-BLSR system, as shown in FIG. 21, a work channel can be completely remedied for a fault occurring in one span. However, as shown in FIG. 28, there is a problem that when two or more failure points occur, that is, the line cannot be repaired for a multipoint failure. In addition, 2F where PCA method is set
-In the BLSR system, when a failure as shown in FIG. 21 occurs, it is possible to relieve only the work channel by the same operation as when PCA is not set. However, at this time, since the protection channel is used to rescue the work channel, it is not possible to relieve the traffic that normally passed through the protection channel. For this reason, PCA
There is a drawback that the traffic passing through the protection channel at the time of setting is limited to data of low importance.

In the 4F-BLSR system, 2F-BL
While the SR system does not tolerate multipoint faults, it can tolerate multipoint faults (depending on the type of fault).
However, the equipment scale is 2F-BLSR system.
Since the configuration is doubled, there is a problem that a huge cost is required for system construction. Also, 4F-BLSR
When a failure occurs when the PCA system is adopted in the system, traffic on the protection channel side cannot be rescued as in the case of the above-mentioned 2F-BLSR. Therefore, low-importance traffic must be set on the protection channel side. No.

In the UPSR system, when a failure occurs, traffic protection is performed by selecting a protection side on which a path is set in a direction opposite to the work channel side. However, since the channel is not allowed to be used in different spans as in the BLSR system, there is a disadvantage that the transmission capacity of the entire ring is limited.

Further, in the conventional BLSR system, there is a drawback that the number of nodes provided in the ring is limited, so that the expandability as a network is restricted.
That is, in the conventional BLSR system, the exchange of the switching protocol (APS protocol) is performed using the K1 / K2 byte of the section overhead (SOH), but the ITU-T_G. According to the rules of 841,
Since only 4 bits are prepared as an area for storing the node ID of the other party, there is a limitation that only 16 nodes can be set on the same ring.

The following Table 1 shows STM-N (N = 4, 1
6, 64, etc.) 2F-B in an optical ring network
A comparison of each configuration of the LSR, 4F-BLSR and UPSR system will be shown.

[0022]

[Table 1] Further, in the conventional BLSR system, the optical node device that has detected the occurrence of a failure performs a ring switch or the like to rescue traffic by loopback. However, this has the disadvantage that the transmission path of the rescued line becomes longer than the transmission path before the occurrence of the failure, and the transmission delay increases.

Specifically, for example, as shown in FIG.
In the F-BLSR system, when an optical signal is transmitted from the optical node device C to the optical node device A, the optical signal is transmitted to the right via the optical node device B using the optical fiber F2 in a normal state when no failure occurs. Transmitted around. And
For example, when a failure occurs in the optical fiber F2 between the optical node devices A and B (as shown in the figure), the optical node device B that detects the occurrence of the failure transmits an optical signal transmitted through the optical fiber F2 on the side opposite to the failure section. A ring switch is connected to the optical fiber F1 (as shown). Thus, the optical signal sent from the optical node device C to the optical fiber F2 is looped back by the optical node device B and transmitted counterclockwise through the optical fiber F1.

However, in the above-mentioned method, there is a problem that the transmission path becomes long and the delay accompanying the transmission path increases. SUMMARY OF THE INVENTION It is a first object of the present invention to provide a large-capacity optical ring network capable of reliably relieving a line in the event of a failure on the ring network. I do. It is a second object of the present invention to provide an optical ring network capable of arbitrarily adding nodes by eliminating the limitation on the number of nodes in the ring network. It is a third object of the present invention to provide an optical ring network that automatically switches to the shortest route when a failure occurs.

[0025]

In order to achieve the above object, an optical ring network according to a first aspect of the present invention provides an optical ring network in which an upstream optical signal is transmitted between adjacent optical node devices among a plurality of optical node devices. A first optical transmission path and a second optical transmission path through which a downstream optical signal is transmitted, and the optical network comprises a ring-shaped optical communication network. Are connected to each other using a third optical transmission line whose transmission direction of an optical signal coincides with any one of the first and second optical transmission lines. An optical node device having a first interface for receiving an upstream optical signal from the first optical transmission line and a second output unit for transmitting a downstream optical signal to the second optical transmission line; Up the optical transmission line A second interface having a first output unit for transmitting an optical signal of the second type and a second input unit for receiving a downstream optical signal from the second optical transmission line; a third input unit for receiving an optical signal from the third optical transmission line; A third interface having a third output unit for transmitting an optical signal to the third optical transmission line, and a connection state between each input / output unit of the first to third interfaces according to a failure occurrence state on the ring network. And switch control means capable of performing switching control, and performs line rescue when a failure occurs using three rings formed by the first to third optical transmission lines.

According to the optical ring network having such a configuration, a plurality of optical node devices are connected by three rings, and when a failure occurs on the ring network, the failure can be dealt with. By the switch control means of the optical node device, the transmission path of the optical signal that has normally passed through the first and second optical transmission paths is switched to a detour path using the third optical transmission path, and the line is automatically relieved when a failure occurs. It is done on a regular basis. Thus, it is possible to realize an optical ring network having a simple configuration capable of reliably performing traffic rescue in the event of a failure while maximally using the transmission capacities of the first and second optical transmission lines. become.

Further, the optical ring network according to the second invention has a plurality of optical node devices corresponding to the maximum number of nodes determined according to the storage area of the node identification information for identifying the plurality of nodes. Adjacent optical node devices among the optical node devices are connected to each other using a first optical transmission line for transmitting an upstream optical signal and a second optical transmission line for transmitting a downstream optical signal, In an optical ring network constituting a ring-shaped optical communication network, a third optical transmission line used for an upstream working line, a fourth optical transmission line used for a downstream working line, and an upstream protection line A linear ADM node device having an input / output interface for connecting a fifth optical transmission line to be used and a sixth optical transmission line to be used for a downstream protection line, respectively, At least between the optical node device
Are inserted. The optical node device located at one end of the section into which the linear ADM node device is inserted includes a first input unit that receives an upstream optical signal from the first optical transmission line and a downstream optical device that transmits the downstream optical signal to the second optical transmission line. A first interface having a second output for transmitting a signal; a second interface having a third output for transmitting an optical signal to the third optical transmission line and a fourth input for receiving an optical signal from the fourth optical transmission line; When,
A third interface having a fifth output unit for sending an optical signal to the fifth optical transmission line and a sixth input unit for receiving an optical signal from the sixth optical transmission line; According to the fault information shown,
A switch control means capable of controlling a connection state between the input / output units of the third interface; information on the fault information according to a code valid with the optical node device; And fault information replacing means for mutually replacing information according to the valid code in accordance with the output direction of the optical signal. Further, the optical node device located at the other end of the section into which the linear ADM node device is inserted includes a first output unit that sends an upstream optical signal to the first optical transmission line and a downstream from the second optical transmission line. A first interface having a second input unit for receiving an optical signal of the first type, a third input unit for receiving an optical signal from the third optical transmission line, and a fourth output unit for transmitting an optical signal to the fourth optical transmission line; A second interface, a fifth interface for receiving an optical signal from the fifth optical transmission line, and a third interface having a sixth output for transmitting an optical signal to the sixth optical transmission line; Switch control means capable of controlling the connection state between the input / output units of the first to third interfaces, and the fault information,
Information according to a code valid with the optical node device;
Fault information replacing means for mutually replacing information according to a valid code with the linear ADM node device according to the output direction of the optical signal.

According to the optical ring network having such a configuration, even when the number of installed optical node devices reaches the maximum number of nodes, one or more linear ADM node devices are inserted between the optical node devices. As for the optical node device adjacent to the linear ADM node device, three input / output interfaces are provided on the ring network side, and an optical node is added on the ring network by providing a failure information replacement processing function. It is possible to eliminate the conventional restriction by the maximum number of nodes.

In the optical ring network according to the third invention, a first optical transmission line for transmitting upstream optical signals and a downstream optical signal are transmitted between adjacent optical node devices among the plurality of optical node devices. In an optical ring network which is connected to each other by using a second optical transmission line to form a ring-shaped optical communication network, adjacent optical node devices among the plurality of optical node devices are the first and second optical node devices. The two optical node devices are connected to each other using a third optical transmission line through which ring information relating to the transmission status of optical signals on the two optical transmission lines is transmitted, and each of the optical node devices is connected to an optical signal upstream from the first optical transmission line. A first interface having a first input for receiving the first optical signal and a second output for transmitting a downstream optical signal to the second optical transmission line; a first output for transmitting an upstream optical signal to the first optical transmission line; A second interface having a second input unit for receiving a downstream optical signal from the second optical transmission line, and transmitting an optical signal to the third input unit and the third optical transmission line for receiving an optical signal from the third optical transmission line; Third having a third output
An interface, a fault information indicating a fault occurrence state included in the optical signals transmitted on the first and second optical transmission paths, and the ring information transmitted on the third optical transmission path, based on the ring information transmitted from the own device to the ring network; For the insertion optical signal to be inserted into, the shortest route switching means for determining the shortest route to the destination optical node device in the event of a failure, and switching the optical transmission line for outputting the insertion optical signal,
Respectively.

According to the optical ring network having such a configuration, automatic switching to the shortest route upon occurrence of a failure is performed based on ring information transmitted on the third optical transmission line.
The transmission path of the optical signal can be changed to the shortest route earlier than the conventional switching based on loopback.

[0031]

Embodiments of the present invention will be described below with reference to the drawings. First, an optical ring network according to the first invention will be described. A first aspect of the present invention provides an optical ring network in which a plurality of optical node devices are connected by three rings so that traffic can be reliably rescued when a failure occurs.

FIG. 1 is a diagram showing a basic configuration of an optical ring network according to an embodiment of the first invention. In FIG. 1, the optical ring network according to the present embodiment has, for example, four optical node devices (NEs) 1 to 4 and three adjacent optical node devices as first to third optical transmission lines. The optical fibers F1 to F3 are mutually connected to form a ring-shaped optical communication network.

Although the configuration having four nodes is shown here as an example, the number of nodes in the present invention is not limited to this. For example, the above-mentioned ITU-T
In the case of complying with the rules, it is possible to provide a maximum of 16 nodes.

The optical fiber F1 is connected to each of the optical node devices 1-4.
Is formed, and an optical signal is transmitted counterclockwise (upward direction). The optical fiber F2 forms a second ring, and the optical signal is transmitted clockwise (downward). Further, the optical fiber F3 forms a third ring, and the optical signal is transmitted counterclockwise. The transmission direction of the optical signal in each ring is set in advance to a single direction. In addition,
Here, the transmission direction of the optical signal of the third ring is set to match the transmission direction of the first ring, but may be set to match the transmission direction of the second ring.

In this embodiment, all of the transmission capacities of the first ring and the second ring are used for work channels (for working lines). The third ring has a transmission capacity equal to the transmission capacity of each of the first and second rings, and is used for a protection channel (for a protection line).
Used as

FIG. 2 is a block diagram showing a configuration example of each optical node device. In FIG. 2, each of the optical node devices 1 to 4
Are the first to the first receiving optical signals from the optical fibers F1 to F3.
Input units 11, 21, 31 serving as three input units, output units 12, 22, 32 serving as first to third output units for sending optical signals to optical fibers F1 to F3, and receiving optical signals from outside the ring network. An input unit 41, an output unit 42 for sending an optical signal outside the ring network,
Switch control circuit (SW) 5 as switch control means for switching and controlling the connection state between the input / output units.
0, respectively.

Here, the input unit 11 connected to the optical fiber F1 and the optical fiber F as the second optical transmission line are used.
The combination of the output unit 22 connected to the optical fiber F2 corresponds to the first interface, the combination of the input unit 21 connected to the optical fiber F2 and the output unit 12 connected to the optical fiber F1 corresponds to the second interface, and The combination of the input unit 31 and the output unit 32 to be connected corresponds to a third interface.

Input unit 41 and output unit 42
Is an interface for inserting and dropping an optical signal to and from a ring network. In the figure, each unit is shown as one unit, but it may have a plurality of input / output units corresponding to channels to be inserted / branched. To give a specific example, 10 corresponding to STM-64
For the Gb / s optical ring network, a plurality of interfaces for 2.5 Gb / s corresponding to STM-16 can be provided on the add / drop side.

As will be described later, the switch control circuit 50 controls each of the input units 11, 21, 31, and 41 and each of the output units 12, 22, 32, and 42 in accordance with the occurrence of a failure on the first and second rings. By controlling the connection state between the two, the transmission path of the optical signal bypassing the faulty section is set, and the traffic is relieved.

Next, the operation of the optical ring network configured as described above will be described. In normal times when no failure occurs on the optical ring network, optical signals are transmitted between required nodes using the first ring and the second ring. That is, each of the optical node devices 1 to 4
Connects the input unit 11 and the output unit 12 with respect to the first ring and transmits the input unit 21 and the output unit with respect to the second ring when transmitting optical signals transmitted through the first and second rings to adjacent nodes, respectively. 22 are connected. When splitting the optical signal transmitted through the first or second ring, the input unit 11 or 21 and the output unit 42 are connected. When an optical signal from outside the ring network is inserted into the first or second ring, the input unit 41 and the output unit 12 or 22 are connected.

When a failure occurs on the first ring or the second ring, the switch control circuit 50 in the corresponding optical node device performs a switching operation so as to bypass the failure section using the third ring. .

For example, as shown in FIG. 3A, on the first ring between the optical node devices 2 and 3 (the optical fiber F1 or the output unit 12 of the optical node device 2 or the input unit 11 of the optical node device 3). ), A failure occurs (hereinafter referred to as failure 1), and the optical node devices 2 and 3 located at both ends of the failure section perform a span switch from the first ring to the third ring. When a span switch for the first ring transmits an optical signal transmitted through the first ring to an adjacent node, a connection between the input unit 11 and the output unit 12 in the normal state is changed to the optical node device 2.
For the optical node device 3, the switching operation is switched to connect the input unit 31 and the output unit 12. Optical node devices 2 and 3
The connection state of the second ring and the connection states of the other optical node devices 1 and 4 are the same as in the normal state.

The switching operation at the time of the occurrence of a failure as described above is a so-called uni-directional SW (Uni-directional SW) in which the switching control of the corresponding optical node device is executed only for the span in which the failure has occurred. To achieve.
This is one of the features of the present embodiment which is different from the so-called bi-directional simultaneous switching control (Bi-directional SW) in the conventional 2F-BLSR system.

Specifically, in the conventional 2F-BLSR system, when a failure occurs, a ring switch is generated across the corresponding span, and the switching control is performed simultaneously in both directions. That is, when a failure occurs in the first ring,
Switching control is also performed on the second ring where no failure has occurred. On the other hand, in the present embodiment, the switching control is performed only for the first ring in which a failure has actually occurred. Therefore, the optical ring network according to the present embodiment is a 3F-type optical network using three optical fiber rings.
ULSR (3-Fiber Uni-directional Line Switched Ri
ng) It can be said that the system is configured. In this optical ring network, the number of instantaneous steps as a ring system does not change, but BLSR
Unlike this, it can be expected that the number of channels that are interrupted can be limited.

Further, for example, as shown in FIG.
If a failure also occurs on the first ring between the optical node devices 4 and 1 (hereinafter referred to as failure 1 '), and if the failures 1 and 1' occur simultaneously, the optical node devices 4 and 1 will also receive the first failure. By performing the span switch from the ring to the third ring, the traffic on the first ring side is rescued. With respect to such failures occurring simultaneously in different spans, the conventional 2F-BLSR system cannot rescue traffic.

Further, as shown in FIG. 4, for example, on the second ring between the optical node devices 2 and 3 (the optical fiber F2 or the output unit 22 of the optical node device 2 or the input unit 21 of the optical node device 3). A failure occurs (hereinafter, failure 2
However, when the failures 1 and 2 occur simultaneously, the optical node devices 2 and 3 located at both ends of the failure section perform a span switch on the first ring and perform a ring switch on the second ring. When transmitting an optical signal transmitted through the second ring to an adjacent node, the ring switch for the second ring replaces the connection between the input unit 21 and the output unit 22 in the normal state with the optical node device 2. For the optical node device 3, a switching operation is performed to switch between the input unit 31 and the output unit 22 and to connect between the input unit 21 and the output unit 32.

The switching operation of each optical node device at the time of occurrence of a failure as described above is controlled by transmitting and responding to a switching request and the like using the APS protocol. The switching control using the APS protocol is an improvement on a part of the method implemented in the conventional 2F-BLSR system or the like. Specifically, the K1 / K2 byte of the section overhead (SOH) is used. Is used.

FIG. 5 is a diagram showing a specific code of K1 / K2 bytes used in the present embodiment.
The byte (B) indicates the K2 byte. FIG.
In the K1 byte of (A), bits 1 to 4 indicate a switching request, and bits 5 to 8 indicate a destination node ID of the switching request. This switching request is composed of 16 types of request codes defined in advance, and indicates a request corresponding to a failure occurrence state or the like by a 4-bit code. When each of the optical node devices receives the above switching request, it performs a switching operation according to the request. On the other hand, FIG.
In the K2 byte of (B), bits 1 to 4 represent the source node ID of the switching request, bit 5 represents the K1 / K2 byte transmission path (short path / long path), and bits 6 to 8 represent the source node. Status (switching state)
Represents

Each of these K1 / K2 byte codes basically conforms to the ITU-T standard. However, among the codes indicating the status of the source node, I
"10" specified for future expansion by the TU-T
“1” and “100” are newly defined as codes representing “switch on” and “switch off”, respectively.

Here, a specific switching operation using K1 / K2 bytes in this embodiment will be described.
However, since the switching control using the K1 byte is performed in accordance with the ITU-T regulations as in the related art, the switching control using the K2 byte is mainly described in FIG.
This will be described in detail with reference to FIG.

First, as shown in FIG. 6A, at the time of normal operation when no failure occurs, all the optical node devices 1 to 4
Requests the K1 byte switch request to “NR (No Reques
t) ", and K1 / K2 bytes with the status of the K2 byte source node set to" IDLE "are transmitted in both the short path and the long path, whereby the entire network enters an idle state. In the following, the content represented by the K1 byte is represented by K1 = (switch request)
/ (Destination node ID; NE1-4)
The content represented by the K2 byte is expressed as K2 = (source node ID;
NE1-4) / (transmission route) / (status of source node).

As shown in FIG. 6B, for example, when a failure occurs in the optical fiber F1 between the optical node devices 2 and 3, the optical node device 3 transmits the optical signal from the optical node device 2. The optical node device 4 detects that the reception has ceased.
K1 = SF-S (Si
gnal Fail Span) / NE2, K2 = NE3 / long path / switch-off, while using the optical fiber F2 for the optical node device 2, K1 = SF-S / NE
2. Send K2 = NE3 / short path / switch off. The optical node device 4 receiving the K1 / K2 byte,
When confirming that the destination node ID is not the own node, 1 passes K1 / K2 bytes (Path through).
The optical node device 2 receives the K1 /
When it is confirmed that the transmission destination of the K2 byte is the own node, the transmission source is the optical node device 3, and the switching request is SF-S, the optical fiber on the optical node device 3 side as shown in FIG. The optical signal transmitted to F1 is converted to an optical fiber F3.
Perform a span switch to switch to send to.

Next, the optical node device 2 is
K1 = RR-S (Re
verse Request Span) / NE3, K2 = NE2 / long path / switch on. When the optical node devices 1 and 4 receive the K1 / K2 bytes, confirm that the destination node ID is not the own node and pass the K1 / K2 bytes. When the optical node device 3 confirms that the optical node device 2 has been switched on by the K1 / K2 byte received via the long path, as shown in FIG. The receiving end of the optical signal sent to the fiber F1 is connected to the optical fiber F1 on the optical node device 2 side.
Is performed to switch to the optical fiber F3. By the above-described series of switching operations, an optical signal is transmitted while bypassing a failure that has occurred in the optical fiber F1 between the optical node devices 2 and 3.

As shown in FIG. 7B, for example, when a failure occurs in the optical fiber F2 between the optical node devices 2 and 3, the optical node device 2 It is detected that the reception of the optical signal is stopped, and the optical fiber F2 is used for the optical node device 1, and K1 = SF-S
/ NE3, K2 = NE2 / long path / switch-off, and the optical fiber F3 is used for the optical node device 3, and K1 = SF-S / NE3, K2 = NE2
/ Short pass / switch off. FIG.
(A) shows the state at the time of normal as well as FIG. 6 (A).

Then, the optical node device 3 that has received the K1 / K2 byte via the long path has its destination as its own node, its source as the optical node device 2, and a switching request of S.
After confirming that the signal is FS, the optical signal transmitted to the optical fiber F2 of the optical node device 2 is transmitted to the optical fiber F3 of the optical node device 4 as shown in FIG. Make a ring switch to switch.

Next, the optical node device 3 is
Use the optical fiber F1, and K1 = RR-S / N
Send E2, K2 = NE3 / long path / switch on. The optical node device 2 that has received the K1 / K2 byte via the long path confirms that the optical node device 3 has been switched on, and as shown in FIG. A ring switch is performed to switch the receiving end of the optical signal sent to F2 from the optical fiber F2 on the optical node device 3 side to the optical fiber F3 on the optical node device 1 side. By the above-described series of switching operations, an optical signal is transmitted while bypassing a failure that has occurred in the optical fiber F2 between the optical node devices 2 and 3.

As described above, according to this embodiment, the first and second rings are used as work channels, and the newly provided third ring is used as a protection channel, whereby each transmission of the first and second rings is performed. It is possible to reliably rescue traffic in the event of a failure while maximizing capacity. In addition, even when a multipoint failure occurs, the traffic can be rescued depending on the state of occurrence. Furthermore, since the system configuration of the present embodiment is simpler than the configuration of the conventional 4F-BLSR system, it is possible to reduce costs and improve reliability.

Next, another embodiment according to the first invention will be described. In the above-described embodiment, the case where the first and second rings are used as work channels has been described. Here, as in the case of the conventional 2F-BLSR system,
Consider an embodiment according to the first invention in which each of the transmission capacities of the first and second rings is divided into two and one is used as a work channel and the other is used as a protection channel, and the PCA method is adopted.

The physical configuration of the optical ring network according to the present embodiment is the same as that shown in FIGS. 1 and 2 described above, and when compared with the configuration of the conventional 2F-BLSR system, each optical node device is It is characterized by having an interface corresponding to the third ring.

In the optical ring network having such a configuration, for example, as shown in FIG. 8, when a failure occurs in the optical fibers F1 and F2 between the optical node devices 2 and 3, when the conventional 2F-BLSR system is used. In the same manner as described above, the optical node devices 2 and 3 located at both ends of the failure section perform the ring switch for the first and second rings, and convert the optical signal passing through the work channel side of the first ring to the protection channel of the second ring. The optical signal that has passed through the work channel side of the second ring is sent to the protection channel side of the first ring (bidirectional simultaneous switching control). At this time,
Normally, optical signals passing through the protection channel sides of the first and second rings have been discarded without being relieved in the past. Is transmitted to The switching control of the optical node devices 2 and 3 is based on the conventional 2F-BLSR
This is performed using K1 / K2 bytes as in the case of the system.

As described above, according to the present embodiment, the conventional P
With respect to the CA system 2F-BLSR system, each optical node device is provided with an interface corresponding to the third ring, so that when a failure occurs, only the optical signal on the work channel side of the first and second rings is used. Also, the optical signal on the protection channel side can be rescued. This eliminates the conventional restriction that less important traffic must be set on the protection channel side.

In the above-described embodiment, the conventional 2F-link is used for the failure occurrence on the first ring or the second ring.
The case where the bidirectional simultaneous switching control is executed in the same manner as in the case of the BLSR system has been described. However, it is also possible to relieve traffic when a failure occurs by the above-described one-way independent switching control.

In the case of the above-described one-way independent switching control, for example, as shown in FIG.
When the failure 1 occurs on the first ring between the three, the optical node devices 2 and 3 located at both ends of the failure section perform a span switch of the first ring and the third ring, and have passed through the first ring. Optical signals in both the work channel (WK) and the protection channel (PTCT)
And bypasses the optical fiber F3. Further, for example, as shown in FIG. 10, when a failure 2 occurs on the second ring between the optical node devices 2 and 3, the optical node devices 2 and 3 perform the ring switch of the second ring and the third ring. , The optical signals of both the work channel and the protection channel that have passed through the second ring bypass the obstacle 2 and pass through the optical fiber F3.

Further, as shown in FIG. 11, for example, when the above-mentioned faults 1 and 2 and a fault 3 on the first ring between the optical node devices 3 and 4 occur simultaneously, the optical node device 2 The ring switch of the first ring and the second ring is performed, the optical node device 3 performs the ring switch of the second ring and the third ring, and the optical node device 4 performs the span switch from the third ring to the first ring. As a result, a bidirectional path is formed between the optical node devices 2-1-4-3, and each optical signal on the work channel side that has passed through the first and second rings is relieved. When a multipoint fault occurs in which faults 1 to 3 occur at the same time,
Although it is not possible to rescue each optical signal on the protection channel side that has passed through the ring, it is possible to realize rescue of traffic on the work channel side, which was difficult in the conventional 2F-BLSR system.

Next, an optical ring network according to the second invention will be described. The second invention is a conventional 2F-B
Provided is an optical ring network that eliminates the limitation on the maximum number of nodes in an LSR system.

FIG. 12 is a diagram showing the entire configuration of the optical ring network according to the second embodiment of the present invention. FIG.
Is an ITU-T_G. 84
In the conventional 2F-BLSR system including 16 optical node devices 1 to 16 that conforms to the rule of 1 and matches the maximum number of nodes, for example, 1
The seventh optical node device 17 is added.

The added optical node device 17 is a BLSR
It is not an optical node device corresponding to the system, but a linear AD
An optical node device corresponding to the M system is used. A linear ADM system, for example, as shown in FIG. 13, connects a work channel (WK) between two terminating devices (LTE).
ADM node and an optical fiber for protection channel (PTCT) are connected in two directions by two optical fibers, each of which is a total of four optical fibers. ). This linear ADM node device
In the present embodiment, it is used as the additional optical node device 17.

In order to enable the addition of the optical node device 17, the optical node devices 1 and 16 adjacent to the additional optical node device 17 are different from the other optical node devices 2 to 15 in hardware configuration. It must be different. That is, between the optical node devices 1 and 17 and the optical node device 1
Between nodes 7 and 16, so-called 1 + 1 line protection is configured, so that optical node devices 1 and 16 having corresponding input / output interfaces are required.

FIG. 14 is a diagram showing a specific configuration example of the optical node devices 1 and 16 and the additional optical node device 17.
14, an optical node device (NE) 1 includes input units 11, 21, 31, 41 and output units 12, 2.
2, 32, and 42, and a control circuit 60 as switch control means and fault information replacement means.

The input unit 11 of the optical node device 1 (the first unit)
The input unit) is an optical fiber F1 connected to the optical node device 2.
(First optical transmission line), and receives an optical signal from the output unit 1
2 (second output unit) sends an optical signal to an optical fiber F2 (second optical transmission line) connected to the optical node device 2 (first interface).

The input unit 21 (fourth input unit) receives the optical signal sent from the optical fiber F4 (fourth optical transmission line) on the work channel side connected to the optical node device 17,
The output unit 22 (third output unit) is an optical node device 17
An optical signal is sent to the optical fiber F3 (third optical transmission line) on the work channel side connected to the second (second interface).

The input unit 31 (sixth input unit) receives an optical signal transmitted from the optical fiber F6 (sixth optical transmission line) on the protection channel connected to the optical node device 17, and receives the output unit 32 (sixth input unit). The fifth output unit) sends an optical signal to the optical fiber F5 (fifth optical transmission line) on the protection channel connected to the optical node device 17 (third interface).

The input unit 41 receives an optical signal inserted from outside the ring network, and
Sends the optical signal branched from the ring network to the outside. The control circuit 60 controls the connection state between the input / output units and performs a process of replacing K1 / K2 bytes in the SOH.

Similarly to the optical node device 1, the optical node device 16 controls the input units 11, 21, 31, and 41, the output units 12, 22, 32, and 42, and the control as switch control means and fault information replacement means. And a circuit 60.

The input unit 11 (second input unit) of the optical node device 16 receives an optical signal from the optical fiber F2 (second optical transmission line) connected to the optical node device 15, and receives the output signal from the output unit 12 (first output unit). Unit) sends an optical signal to the optical fiber F1 (first optical transmission line) connected to the optical node device 15 (first unit).
interface).

The input unit 21 (third input unit) receives an optical signal sent from the optical fiber F3 (third optical transmission line) on the work channel side connected to the optical node device 17,
The output unit 22 (fourth output unit) is an optical node device 17
An optical signal is sent to the optical fiber F4 (fourth optical transmission line) on the work channel side connected to the second (second interface).

The input unit 31 (fifth input unit) receives an optical signal transmitted from the optical fiber F5 (fifth optical transmission line) on the protection channel connected to the optical node device 17, and receives the output unit 32 (fifth input unit). The sixth output unit) sends an optical signal to the optical fiber F6 (sixth optical transmission line) on the protection channel side connected to the optical node device 17 (third interface).

The input unit 41 receives an optical signal inserted from outside the ring network, and
Sends the optical signal branched from the ring network to the outside. The control circuit 60 controls the connection state between the input / output units and performs a process of replacing K1 / K2 bytes in the SOH.

As described above, the optical node devices 1 and 16 have a configuration in which, on the ring network side, three interfaces are provided as a pair of an input unit and an output unit. The configuration is the same as that of the device.

Optical node device (linear ADM node device)
17 is an input unit 111, 121, 131, 14
1, 151 and output units 112, 122, 132,
142 and 151, and a control circuit 160.

The input unit 111 receives a work channel side optical signal sent from the optical node device 1, the input unit 121 receives a work channel side optical signal sent from the optical node device 16, and the input unit 131 receives an optical node device. The input unit 141 receives the optical signal on the protection channel side transmitted from the optical node device 16, and receives the optical signal on the protection channel side transmitted from the optical node device 16.

The output unit 112 sends an optical signal on the work channel side to the optical node device 1, the output unit 122 sends an optical signal on the work channel side to the optical node device 16,
The output unit 132 sends an optical signal on the protection channel side to the optical node device 1, and the output unit 142 sends an optical signal on the protection channel side to the optical node device 16.

The input unit 151 receives an optical signal inserted from outside the ring network, and
52 sends the optical signal branched from the ring network to the outside. The control circuit 160 switches the connection state between the input / output units to control the insertion, branching, and passage of the optical signal.

The configuration of the optical node devices 2 to 15 other than the above is the same as that of the optical node device used in the conventional 2F-BLSR system, so that the description is omitted here.
In the optical ring network configured as described above, since the 2F-BLSR system and the linear ADM system coexist in the same ring, K1 / K2 of the section overhead (SOH) used for switching control when a failure occurs.
Bytes (failure information) must be handled independently by each system. That is, the K1 / K2 bytes exchanged between the BLSR system and the linear ADM system are as follows:
Both exist in the same area of the SOH, but the K1 / K2 bytes used in the BLSR system follow the APS code, and the K1 / K2 bytes used in the linear ADM system follow the MSP code, so a common K1 / K2 byte is used in each system. Then, erroneous switching control is performed in one system.

Therefore, in the present embodiment, the function of replacing the K1 / K2 bytes is realized in the control circuit 60 of the optical node devices 1 and 16 adjacent to the additional optical node device 17. Specifically, when transmitting the optical signal from the optical node device 2 to the optical node device 17, the control circuit 60 of the optical node device 1 uses the KPS according to the APS code included in the optical signal.
1 / K2 bytes of data are read, and the data is transferred to a predetermined unused area in the same SOH. The transfer source area is provided in accordance with the occurrence of a failure between the optical node devices 1 and 17. K1 / K according to generated MSP code
Record 2 bytes. On the other hand, when transmitting an optical signal from the optical node device 17 to the optical node device 2, data of K1 / K2 bytes is read in accordance with the MSP code included in the optical signal, and the data is read from the read area. , S
The K1 / K2 byte data according to the APS code recorded in a predetermined unused area in the OH is transferred. Also, in the control circuit 60 of the optical node device 16, the same replacement processing as in the case of the optical node device 1 is executed.

Since the optical node devices 1 and 16 have such a K1 / K2 byte replacement processing function, when the optical ring network is viewed from the 2F-BLSR system side, the optical node device 1 and the optical node device 16 are provided. The switching control at the time of the occurrence of a failure is performed in a state where are directly connected equivalently. Also, when viewed from the linear ADM system side, 1 + 1 line protection is configured between the optical node devices 1 and 17 and between the optical node devices 16 and 17, and when a failure occurs in these sections, the work channel The line is relieved by switching the line from the protection channel to the protection channel.

As the optical node device 17 to be added, the data stored in a predetermined unused area in the SOH included in the optical signal received from one side is not rewritten without being rewritten. It should be noted that it is necessary to provide a function of passing through the side of the.

As described above, according to the present embodiment, K1
For the 2F-BLSR system that has reached the maximum number of nodes determined according to the area storing the destination node ID of / K2 bytes, a linear ADM node device is used as an additional optical node device, and an optical node adjacent to the additional optical node device is used. As for the device, similarly to the optical node device used in the above-mentioned first invention, the ring network is provided with three input / output interfaces, and the K1 / K
By providing a 2-byte replacement function, it is possible to eliminate the limitation on the maximum number of nodes.

In the above embodiment, one linear ADM node device is added between the optical node devices 1 and 16, but two or more linear ADM node devices are added between the optical node devices 1 and 16. It is of course possible to connect the devices in a line. The span in which the linear ADM node device is added is not limited to the span between the optical node devices 1 and 16, and may be another span. Further, an application in which a linear ADM node device is added to a plurality of non-adjacent spans is also possible.

Next, an optical ring network according to the third invention will be described. In the conventional BLSR system, when a failure occurs, the line is relieved by loopback. However, this increases the transmission delay. In order to avoid this problem, the third invention provides an optical ring network that performs line rescue using the shortest route.

FIG. 15 is a diagram showing an entire configuration of an optical ring network according to the third embodiment of the present invention. FIG.
The basic configuration of the optical ring network shown in FIG.
As in the case shown in FIG. 1, for example, four optical node devices (NEs) 1 to 4 are provided, and adjacent optical node devices are connected to each other by three optical fibers F1 to F3 to form a ring-shaped optical node device. Form an optical communication network. The first ring formed by the optical fiber F1 transmits the optical signal counterclockwise, and the second ring formed by the optical fiber F2 transmits the optical signal clockwise, and the third ring formed by the optical fiber F3.
The optical signal is transmitted counterclockwise through the ring.

Although the configuration having four nodes has been described as an example, the number of nodes in the optical ring network is not limited to this. Further, although the transmission direction of the optical signal of the third ring is set to match the transmission direction of the first ring, it may be set to match the transmission direction of the second ring.

In this embodiment, as in the case of the conventional 2F-BLSR system, each transmission capacity of the first and second rings is divided into two equal parts, one is used as a work channel, the other is used as a protection channel, and Each optical node device 1
4 to 4 have an automatic switching and rescue function when a failure occurs. Further, in the present optical ring network, the first,
Information (hereinafter referred to as ring information) relating to the line status of the optical signal data on the two rings is collected and transmitted via the third ring. Each optical node device automatically and quickly switches to the shortest route based on the ring information when a failure occurs.

Here, the operation when a failure occurs in the present optical ring network will be described with reference to a specific example. For example, as shown in FIG. 15, a case where an optical signal inserted from the optical node device 3 is transmitted to the optical node device 1 is considered. In this case, the optical signal inserted from the optical node device 3 is sent to the work channel side of the optical fiber F2 and transmitted to the optical node device 1 via the optical node device 2 at the normal time when no failure occurs. Shall be. For example, assume that a failure occurs between the optical node devices 1 and 2 on the second ring.

FIG. 16 is a diagram specifically showing the switching operation in the optical node devices 2 to 4 when the above-described failure occurs. FIG. 17 is a functional block diagram for explaining a specific operation in the optical node device 3.

As shown in FIGS. 16 and 17, first,
An optical signal TRIB_CH to be inserted into a specific channel on the ring network is input to the optical node device 3 from the outside, and the optical signal TRIB_CH is sent to the own device ID information insertion unit 3A. In the own device ID information insertion unit 3A,
The optical signal TRIB_CH to which the node information is added is sent to the work channel side of the optical fiber F2, and the optical node device 2
And the selector (SEL) 3D
Also sent to.

The above-mentioned node information includes the optical signal TRIB_C
H is information indicating from which node the node is inserted (here, the node ID of the optical node device 3), and is stored in, for example, the J1 byte (data area for path trace) in the path overhead (POH). , Optical signal TRIB_
It is transmitted together with the CH. From this node information, each of the optical node devices 1 to 4 can determine from which node the optical signal of each channel is inserted. The POH is overhead information that is valid only between the source node and the destination node, and does not affect the node through which the optical signal passes.

In the optical node device 2, when the occurrence of a failure on the second ring with the optical node device 1 is detected,
A ring switch is performed to connect the optical fiber F2 on the optical node device 3 side to the optical fiber F1. As a result, the optical signal transmitted from the optical node device 3 to the optical node device 2 via the work channel side of the optical fiber F2 is looped back by the optical node device 2 and passes through the protection channel side of the optical fiber F1 to the optical node F2. It is returned to the device 3.

In the optical node device 3, the J1 byte monitor unit 3B monitors the J1 byte of the optical signal passing through the protection channel side of the optical fiber F1, and transmits the monitoring result to the determination unit 3C. The determination unit 3C adds the node I of its own device to the J1 byte of the optical signal that has passed through the protection channel side of the optical fiber F1.
Based on the fact that D is stored, it is determined that the optical signal transmitted toward the optical node device 2 is returning to its own device using the route in the opposite direction, and the signal for controlling the operation of the selector 3D is determined. Is output. The selector 3D includes an optical signal on the protection channel side of the optical fiber F1 and the optical signal TRIB_ output from the own device ID information insertion unit 3A.
In response to the control signal from the determination unit 3C, the selector 3D selects the own device ID information insertion unit 3A.
Is controlled so as to select and output the optical signal from. As a result, the optical signal TRIB_CH input to the optical node device 3 is directly sent to the protection channel side of the optical fiber 1 via the own device ID information insertion unit 3A and the selector 3D and transmitted to the optical node device 4. Become like

The same applies to the case where the optical signal TRIB_CH data is separated. If the node ID of the separated channel matches the node ID of the protection channel signal,
Separate the signal on the protection side.

Further, in the present optical ring network, in addition to the above operation, automatic switching to the shortest route based on ring information transmitted on the third ring is simultaneously executed.
Automatic switching to the shortest route based on this ring information is performed by always flowing ring information on the third ring, and transmitting the ring information and the K1 / K2 bytes transmitted along with the optical signals on the first and second rings. According to the information, each optical node device determines the occurrence of a failure on the first and second rings, and quickly switches to the shortest ring.

Specifically, each of the optical node devices 1 to 4 transmits ring information in a format as shown in FIG.
It is inserted in order from the first byte of an arbitrary payload on the third ring. The figure shows the node ID of each device.
Are assigned in order from 0, and the case where channels 1 to 32 are set as the respective work channels of the first and second rings is shown. Connect information is stored. in this case,
Each of the optical node devices 1 to 4 can insert information in the above format from the ID number of its own device × the 35th byte.

Here, the handling of ring information for the optical node device 3 will be described in detail. First, the ring information insertion unit 3E shown in FIG. Ring information is generated and the 70th byte from the first byte of the payload of the third ring (node I
D: 2 × 35 = 70). It should be noted that the ring information insertion unit 3E updates (updates) its own data every time the ring information transmitted by itself returns around the third ring.

The ring information detecting unit 3F of the optical node device 3 detects ring information transmitted from each optical node device via the third ring, and transmits the detection result to the determining unit 3C. The K1 / K2 byte information included in the optical signal transmitted through the first and second rings is transmitted to the determination unit 3C. When a failure occurs on the first and second rings, the K1 / K2 byte information is transmitted. The failure detection is performed based on

The determination unit 3F responds to the occurrence of a failure determined based on K1 / K2 bytes of information by using the ring information detection unit 3F.
It determines whether or not the optical signal TRIB_CH is rescued based on the ring information from, and outputs a signal for controlling the operation of the selector 3D when the rescue is determined. Selector 3D
Is controlled so as to select and output the optical signal from the own device ID information insertion unit 3A according to the control signal from the determination unit 3C. As a result, the optical signal TRIB_CH input to the optical node device 3 is directly sent to the protection channel side of the optical fiber 1 via the own device ID information insertion unit 3A and the selector 3D and transmitted to the optical node device 4. Become like Also, the optical signal TRIB_CH
When separating data, the same procedure as that for inserting data is executed.

As described above, according to the present embodiment, by switching to the shortest route performed based on ring information on the third ring, it becomes possible to realize line relief with a minimum transmission delay. In addition, by confirming that the optical signal transmitted by the own device is returned by the loopback using the information of the J1 byte, it is possible to confirm that the switching control based on the ring information is correct.
Automatic switching to the shortest route when a failure occurs can be executed more reliably.

The hardware configuration of each of the optical node devices 1 to 4 used in each of the first and third embodiments of the present invention and the optical node devices 1 and 16 used in the second embodiment of the present invention. Can be used in common, and an example of a specific device configuration will be described below.

Here, a specific example will be described in which the optical node device according to the present invention is realized by using the optical node device generally used in the conventional 2F-BLSR system and extending its functions. FIG. 19 is a diagram showing a hardware configuration of the optical node device according to the present invention. FIG. 20 is a diagram illustrating a hardware configuration of a general optical node device used in the 2F-BLSR system.

First, in the general optical node device shown in FIG. 20, an aggregate side where the optical fibers F1 and F2 on the ring side are connected, and optical signals are inserted / branched from each node. The optical fiber is connected to a tributary side. For example, in the case of a ring system having a capacity of STM-64, the aggregate side includes STM-64.
Interface cards (IF # 1, # 2), and on the tributary side, STM-16, STM-4 or STM-1 equivalent interface cards (IF # 1 ~ #
8) is equipped. The switch structure (SW Fabric)
Is for selectively connecting between an aggregate interface card and a tributary interface card. The clock unit (CLK) is a circuit that generates or extracts a clock signal for synchronizing each optical node device on the ring network. Further, the control unit (CONT) controls the switching operation of the switch structure unit according to the clock signal from the clock unit.

In contrast to the general optical node device as described above, the optical node device according to the present invention can be equipped with an STM-64 interface card on the tributary side as well, so that the first and second rings can be provided. A transition from a system to which only the first ring can be connected to a system to which the first to third rings can be easily realized.

Specifically, for example, as shown in FIG.
Tributary side interface card # 1,
# 2 is replaced with a unit similar to the interface card on the aggregate side to make an aggregated interface card # 3. However, the present optical node device has a function that allows a unit (package) mounted on the aggregate interface to be used as it is as a tributary interface. Thus, when the function of the optical node device is expanded, it is not necessary to add the device unit, and it is possible to upgrade to the optical node device according to the present invention only by replacing the unit and updating (downloading) the software for system control. Become.

In the hardware configuration of the optical node device, the aggregate interface card for connecting the third ring is equivalent to the STM-64 equivalent to the aggregate interface card for connecting the first and second rings. However, the present invention is not limited to this. For example, similar to the interface card of the tributary side, for example, S
It may correspond to TM-16 or the like, and may realize an interface card for connecting the third ring. In this case, although the transmission capacity of the third ring is reduced, it is possible to provide an effective function as a double rescue function of a very important specific line such as a police station or a fire department.

[0113]

As described above, according to the first aspect, a plurality of optical node devices are connected in a ring shape by first to third optical transmission lines, and the third optical transmission line is used when a failure occurs. By performing line rescue, a simple optical ring network that can reliably perform line rescue in the event of a failure while maximizing the use of each transmission capacity of the first and second optical transmission lines. It can be realized by the configuration.

Further, according to the third invention, in an optical ring network including an optical node device having the maximum number of nodes, a linear ADM node device is used as an additional node, and an optical node device adjacent to the linear ADM node device is used. By providing three interfaces on the ring network side and having a function of replacing fault information, a new optical node can be added.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of an optical ring network of an embodiment according to a first invention.

FIG. 2 is a block diagram showing a configuration example of each optical node device used in the embodiment.

3A and 3B are diagrams illustrating an operation when a failure occurs in the embodiment; FIG. 3A illustrates a case where a failure occurs at one location, and FIG. 3B illustrates a failure occurring at two locations on a first ring; FIG.

FIG. 4 is a diagram illustrating an operation when a failure occurs simultaneously on the first and second rings in the embodiment.

FIG. 5 is a diagram showing specific codes of K1 / K2 bytes used in the embodiment, wherein (A) shows K1 bytes,
(B) shows the K2 byte.

FIG. 6 is a diagram illustrating a specific switching operation using K1 / K2 bytes in the embodiment.

FIG. 7 is a diagram illustrating another specific switching operation using K1 / K2 bytes in the embodiment.

FIG. 8 is a diagram illustrating an operation when a failure occurs in another embodiment according to the first invention.

FIG. 9 is a diagram illustrating an operation when a failure occurs on the first ring in the case of one-way independent switching control according to the other embodiment.

FIG. 10 is a diagram illustrating an operation when a failure occurs on the second ring in the case of one-way independent switching control according to the other embodiment.

FIG. 11 is a diagram illustrating an operation when a multipoint failure occurs on the first and second rings in the case of one-way independent switching control according to the other embodiment.

FIG. 12 is a diagram illustrating an overall configuration of an optical ring network according to an embodiment of the second invention.

FIG. 13 shows a general linear AD according to the embodiment.
FIG. 1 is a diagram illustrating a configuration of an M system.

FIG. 14 is a diagram showing a configuration of a node extension section in the embodiment.

FIG. 15 is a diagram illustrating an entire configuration of an optical ring network according to an embodiment of the third invention.

FIG. 16 is a diagram illustrating a switching operation when a failure occurs in the embodiment.

FIG. 17 is a functional block diagram illustrating a specific operation of the optical node device for inserting an optical signal in the embodiment.

FIG. 18 is a diagram showing an example of a format of ring information used in the embodiment.

FIG. 19 is a diagram showing a hardware configuration of an optical node device according to the present invention.

FIG. 20 is a diagram illustrating a hardware configuration of a general optical node device used for the 2F-BLSR system.

FIG. 21 is a diagram illustrating a configuration example of a conventional 2F-BLSR system.

FIG. 22 is a conceptual diagram in which capacity in a line is divided in a conventional 2F-BLSR system.

FIG. 23 is a diagram illustrating a maximum line capacity in a conventional 2F-BLSR system.

FIG. 24 is a diagram illustrating a configuration example of a conventional 4F-BLSR system.

FIG. 25 is a diagram illustrating a span switch operation when a failure occurs in a conventional 4F-BLSR system.

FIG. 26 is a diagram illustrating a ring switch operation when a failure occurs in a conventional 4F-BLSR system.

FIG. 27 is a diagram illustrating a configuration example of a conventional UPSR system.

FIG. 28 is a diagram illustrating a problem of a conventional 2F-BLSR system.

FIG. 29 is a diagram illustrating an automatic switching operation to a shortest route in a conventional 2F-BLSR system.

[Explanation of symbols]

 1, 2, 3, 4 Optical node device (NE) F1, F2,... F6 Optical fiber 11, 21, 31, 41 Input unit 12, 22, 32, 42 Output unit 50 Switch control circuit (SW) 17 Linear ADM node Device (LNR ADM) 3A Own device ID information insertion unit 3B J1 byte monitor unit 3C determination unit 3D selector (SEL) 3E ring information insertion unit 3F ring information detection unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Ryuichi Moriya 4-1-1, Kamidadanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (72) Hideki Matsui 4-1-1 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa No. 1 Fujitsu Co., Ltd. (72) Inventor Hirotaka Morita 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa F-term within Fujitsu Co., Ltd. 5K002 AA05 BA04 BA06 DA04 DA11 EA05 EA33 FA01 5K031 AA08 CA08 CB10 CB12 CC04 DA11 DA19 DB01 DB14 EA01 EB02 EB05

Claims (7)

[Claims] A first optical transmission line for transmitting an upstream optical signal and a second optical transmission line for transmitting a downstream optical signal are used between adjacent optical node devices among a plurality of optical node devices. In the optical ring network, which is connected to each other to form a ring-shaped optical communication network, the optical signal transmission direction between the adjacent optical node devices among the plurality of optical node devices is the first and second optical signals. A first input unit that is connected to each other using a third optical transmission line that matches one of the transmission directions of the transmission lines, and wherein each of the optical node devices receives an upstream optical signal from the first optical transmission line; And a first interface having a second output unit for sending a downstream optical signal to the second optical transmission line; a first interface for sending an upstream optical signal to the first optical transmission line; Second input for receiving downstream optical signal A third interface having a third input unit for receiving an optical signal from the third optical transmission line and a third output unit for sending an optical signal to the third optical transmission line; And switch control means for switching and controlling the connection state between the input / output units of the first to third interfaces according to the failure occurrence status. An optical ring network wherein a line is relieved when a failure occurs using three formed rings. 2. The optical ring network according to claim 1, wherein the first and second optical transmission lines are respectively used for a working line, the third optical transmission line is used for a protection line, The switch control unit of each of the optical node devices is configured to perform the first to the first operation so that at least one of the upstream and downstream working lines can be rescued using the third optical transmission line in accordance with a failure occurrence situation. An optical ring network for switching and controlling a connection state between input / output units of a third interface. 3. The optical ring network according to claim 1, wherein the first and second optical transmission lines are used for a working line during a normal operation, and one of the lines whose transmission capacity is divided into two when a failure occurs is used as a working line. The other line is used as a backup line, and the third optical transmission line causes a failure in the other line of the first and second optical transmission lines when an optical signal transmitted during normal operation is generated. The switch control means of each of the optical node devices is configured to switch the other line of the first and second optical transmission lines during normal operation according to a failure occurrence condition. An optical ring network for controlling switching of a connection state between input / output units of the first to third interfaces so that a signal can be rescued using the third optical transmission line. Click. 4. An optical system comprising: a plurality of optical node devices corresponding to a maximum number of nodes determined according to a storage area of node identification information for enabling a plurality of nodes to be identified; A first optical transmission line on which an upstream optical signal is transmitted and a second optical transmission line on which a downstream optical signal is transmitted between the node devices.
In an optical ring network connected to each other using an optical transmission line to form a ring-shaped optical communication network, a third optical transmission line used for an upstream working line and a third optical transmission line used for a downstream working line Linear AD having input / output interfaces for connecting four optical transmission lines, a fifth optical transmission line used for an upstream protection line, and a sixth optical transmission line used for a downstream protection line, respectively.
At least one M node device is inserted between the plurality of optical node devices, and an optical node device located at one end of a section into which the linear ADM node device is inserted is an upstream light from the first optical transmission line. A first interface having a first input unit for receiving a signal and a second output unit for sending a downstream optical signal to the second optical transmission line; a third output unit for sending an optical signal to the third optical transmission line; A second interface having a fourth input for receiving an optical signal from the fourth optical transmission line; a fifth output for sending an optical signal to the fifth optical transmission line; and a sixth input for receiving an optical signal from the sixth optical transmission line. A connection state between input / output units of the first to third interfaces according to failure information indicating a failure occurrence state on the network included in the optical signal. Switch control means, for the fault information, information according to a valid code with the optical node device, and information according to a valid code with the linear ADM node device, according to the output direction of the optical signal A fault information replacement unit that replaces each other, wherein the optical node device located at the other end of the section into which the linear ADM node device is inserted has a first output for sending an upstream optical signal to the first optical transmission line. A first interface having a unit and a second input unit for receiving a downstream optical signal from the second optical transmission line; and a third input unit for receiving an optical signal from the third optical transmission line and an optical signal to the fourth optical transmission line. A second interface having a fourth output for transmitting a signal; a third interface having a fifth input for receiving an optical signal from the fifth optical transmission line and a sixth output for transmitting an optical signal to the sixth optical transmission line; A switch control means capable of controlling a connection state between input / output units of the first to third interfaces in accordance with the failure information; and the failure information is valid between the optical node device. Fault information replacement means for mutually replacing information according to a simple code and information according to a code valid between the linear ADM node device in accordance with the output direction of an optical signal. Optical ring network. 5. A first optical transmission line for transmitting upstream optical signals and a second optical transmission line for transmitting downstream optical signals between adjacent optical node devices among the plurality of optical node devices. In the optical ring network, which is connected to each other to form a ring-shaped optical communication network, adjacent optical node devices among the plurality of optical node devices are configured to transmit optical signals on the first and second optical transmission lines. The optical node devices are connected to each other using a third optical transmission line through which ring information regarding a transmission state is transmitted, and each of the optical node devices receives an upstream optical signal from the first optical transmission line; and A first interface having a second output unit for transmitting a downstream optical signal to a second optical transmission line; a first output unit for transmitting an upstream optical signal to the first optical transmission line; and a downstream interface for transmitting the downstream optical signal to the second optical transmission line. Receive optical signal A second interface having a second input unit, a third interface having a third input unit receiving an optical signal from the third optical transmission line, and a third output unit sending an optical signal to the third optical transmission line, Insertion from its own device into a ring network based on fault information indicating a fault occurrence state included in an optical signal transmitted on the first and second optical transmission paths and the ring information transmitted on the third optical transmission path A shortest route switching means for determining the shortest route to the destination optical node device at the time of occurrence of a failure and switching the optical transmission line for outputting the insertion optical signal. And optical ring network. 6. The optical ring network according to claim 5, wherein said shortest route switching means transmits node identification information of its own device and cross-connect information on an insertion optical signal to said third optical path via said third interface. A ring information insertion unit to be inserted into a transmission line; a ring information detection unit to detect the ring information input from the third optical transmission line via the third interface; a ring detected by the ring information detection unit A determination unit that determines the shortest route based on information and the failure information; and a switch unit that switches an optical transmission path that outputs the insertion optical signal according to a determination result of the determination unit. And optical ring network. 7. The optical ring network according to claim 1, wherein said third interface connects an optical transmission line on the side of inserting / branching an optical signal to / from the ring network. An optical ring network using a part of a plurality of input / output interfaces.