JPH11112422A - Multi-wavelength network switching device and multi-wavelength optical ring network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a path switch in a wavelength unit by providing a switching means for selectively supplying the signal light of a prescribed wavelength from the wavelength separation means of a present use system and a stand-by system for one of a wavelength multiplexing means of the present use system and the stand-by system. SOLUTION: Signal light transmitted from the optical fiber cable 30a of a present use line 30 is divided into respective wavelength λ1 to λn by a wavelength separation device to be supplied for the optical input ports X0 of respective present use/stand-by switching circuits 48-1 to 48-n corresponding to the respective wavelength λ1 to λn. The circuits 48-1 to 48-n are provided with optical input ports X0 to X3 and optical output ports Y0 to Y3 to switch present use lines 30, 34 and stand-by lines 32 and 36 concerning the signal light of the respective wavelength λ1 to λn. The signal light of the wavelength λ1 to λn outputted from the optical output port Y0 of the circuits 48-1 to 48-n is wavelength-multiplexed by a wavelength multiplexer 52a and sent to the optical fiber cable 34a of a present use line 34.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength division multiplexing network switching device for switching between a working system and a protection system in a wavelength division multiplexing transmission system, and a wavelength multiplexing ring optical network system using the wavelength division multiplexing network switching device.

[0002]

2. Description of the Related Art In a ring optical network system formed by connecting a plurality of optical digital transmission terminal nodes in a ring by an optical transmission line, a network for switching between a working line and a protection line to an optical digital transmission terminal node has conventionally been used. A switching device is provided, and a function of adding / dropping a low-speed signal in a time-division multiplex manner forms a path connecting low-speed signal levels between nodes of the ring optical network. If
They switched to a path opposite the ring to replace the broken path.

FIG. 13 shows a conventional network switching device (NPE:
Network Protection Equipment
ent) is shown. Here, STM-1 (Synchronous) is performed by a time division multiplexing method.
Transfer Module Level 1)
-16 (Syn-16) obtained by multiplexing 16 signals on the time axis
chronous Transfer Module
Level 16) Synchronous Digital Hierarchy (SDH: Synchronous Digital)
It is assumed that an optical signal using a Hierarchy frame can be transmitted through a working transmission line (working transmission line) and a protection transmission line (protection transmission line). Each of the working transmission line and the call transmission line includes a pair of optical fiber transmission lines including an upstream optical fiber transmission line and a downstream optical fiber transmission line.

FIG. 17 shows an example of a frame structure of an SDH frame. As in a normal transmission frame, an overhead part is added before an information field containing information to be transmitted. The overhead section includes a frame synchronization signal and a control field including operation management information and the like.

[0005] 10 and 14 are connected to the working transmission line,
High-speed interface that can follow -16 optical signals, 1
Reference numerals 2 and 16 denote high-speed interfaces which can be connected to the spare transmission line and follow STM-16 optical signals. These high-speed interfaces 10 to 16 each include a light receiving element for converting an optical signal from an optical transmission line into an electric signal, and a laser element for converting an electric signal to an optical signal, and a means for converting electricity to light and light to electricity. Function as 18 is connected to the transmission / reception device 20 of the node where the network switching device is installed,
These are low-speed interfaces for terminating low-speed electric signals of STM-1, and these interfaces 10 to 18 are connected to the electric add / drop device 22.

The add / drop device 22 includes a low-speed interface, if necessary, in one of the 16 time slots of the STM-16 signal from the high-speed interfaces 10, 12, 14, 16 assigned to this node. 18 is a network switching device in a narrow sense that adds an STM-1 signal from the low-speed interface 18 to the working transmission line or the protection transmission line and switches to the protection system in the event of a failure in the working system. The add / drop device 22 multiplexes the STM-1 signal into the STM-16 signal on the time axis 4 at the connection part of the high-speed interfaces 10 to 16, and separates the STM-16 signal into the STM-1 signal on the time axis. A demultiplexer is provided.

As shown in FIG. 14, five nodes 1-5
Assume a ring optical network system consisting of a four-fiber ring in which four optical fiber transmission lines (two of which are active uplink and downlink and the other two are standby uplink and downlink) are connected in a ring. I do. In a normal state, any two nodes on the ring are connected by an STM-1 signal using a working optical fiber pair transmission line. In FIG. 14, the path of the STM-1 signal between the node 2 and the node 4 is shown by a thick solid line.

As shown in FIG. 15, node 1 and node 2
It is assumed that a failure has occurred in the working transmission path between the two. At this time, the nodes 1 and 2 sandwiching the point of failure are connected to the SOH of the STM-16 signal.
The K byte of (Section Over Head) includes the information of the fault occurrence position and sends it out in both directions (the direction of the fault point and the reverse direction). The network switching devices of the nodes 1 and 2 transmit the A based on the K byte information transmitted from the nodes 2 and 1 and received via a long path different from the normal path.
PS (Automatic Protection S)
(switch), the transmission path used in the failure section is switched to the backup transmission path. Therefore, for example, for signal transmission between the node 2 and the node 4, a spare transmission path is used between the nodes 1 and 2. This protocol is, for example, ITU-
Recommendation GG. 841 Annex A. This recommendation is for a ring network with a single wavelength ultra-long haul fiber optic cable.

As shown in FIG. 16, when a failure occurs in the optical fiber cable between the nodes 1 and 2 (that is, when both the working transmission line and the protection transmission line become unavailable).
The network switching devices of the nodes 1 and 2 use the STM on the active transmission path.
Using the K bytes of the overheader of the -16 signal, the information of the section where the failure has occurred is transmitted to the other nodes 3, 4, and 5. The network switching device of each node 3, 4, 5
S of the working transmission line affected by the cable failure between the two
Ring AP with K byte information for TM-1 signal
According to the S control, the switching to the reverse protection transmission line for avoiding the cable failure is executed. Thereby, for example, node 2
A standby transmission path via the node 3 is used for signal transmission between the node 3 and the node 4.

The conventional network switching device needs to have a bridge function for simultaneously outputting a transmission signal to the working transmission line and the protection transmission line, and for reception, a switching function for switching from the working transmission line to the protection transmission line and vice versa. Need to have This is because, when the fault is recovered, it is necessary that signals are simultaneously transmitted to the working transmission line and the protection transmission line when returning to the normal state according to the APS control using the K-byte information.

On the other hand, in recent years, in order to increase the capacity of an optical transmission system, wavelength division multiplexing technology has been widely used, and realization of a ring optical network using a wavelength division multiplexing method has been studied. In the ring optical network, a network switching device is used for a ring corresponding to each wavelength,
A method of rescuing a network at the time of failure at the STM-1 signal level using the same configuration as that of the related art can be considered.

Since the high-speed interface of such a network switching apparatus is compatible with 2.5 Gb / s STM-16 signals, for example, the signal transmission speed is 5 Gb / s.
Alternatively, at 10 Gb / s, a transmission terminal device for demultiplexing the STM-16 signal is inserted between the transmission line and the network switching device, and each node has two network switching devices.
It is necessary to prepare four or four units.

FIG. 18 is a schematic block diagram of a network switching system when the signal transmission speed is 5 Gb / s. An optical signal of 5 Gb / s is transmitted through both the working transmission line and the protection transmission line. Two network switching devices 210 and 212 respectively corresponding to 2.5 Gb / s are prepared, and the network switching device 21 is provided.
0 is connected to the active transmission line via the transmission terminal devices 214 and 216, and the backup transmission line is connected to the transmission terminal devices 218 and 220.
Connect through. An optical signal of 2.5 Gb / s is transmitted between the transmission terminal devices 214 to 220 and the network switching devices 210 and 212.

FIG. 19 is a schematic block diagram of the transmission terminal units 214 to 220. Network switching devices 210, 21
2.5 Gb / s optical signals from
The signal is converted into an electric signal by 22, 22. The error correction encoding circuits 226 and 228 respectively
An error correction code of 1 bit is added to 8 outputs to 2,224 outputs. The multiplexer 230 multiplexes the outputs of the error correction circuits 226 and 228 on the time axis and
/ S. The light emitting device 232 converts an output signal of the multiplexing device 230 into a 1.5 μm band optical signal. Light emitting device 2
32 is optically amplified by an optical amplifier 234 and transmitted to a transmission line.

The optical signal input from the transmission path is
6 and is converted into an electric signal by the light receiving device 238. The separation device 240 outputs the output of the light receiving device 238 (5
Gb / s) is separated into two 2.5 Gb / s signals and supplied to error correction circuits 242 and 244, respectively. The error correction circuits 242 and 244 correct the transmission error of the signal from the demultiplexer 240 using the error correction code added at the signal transmission source, and supply the same to the light emitting devices 246 and 248. The light emitting devices 246 and 248 convert the electric signal from the error correction circuit 242 into a 1.3 μm band optical signal, and
0,212.

However, when wavelength multiplexing transmission signals, as the number of multiplexed wavelengths increases, the number of virtual four-fiber rings corresponding to each wavelength increases, and the number of network switching devices corresponding to the number of virtual rings becomes necessary. Become. At present, 20 to 32 wavelengths are being considered as the number of multiplexed wavelengths. In response to this, each node requires 2 to 2 when the signal transmission speed is 5 Gb / s.
When the signal transmission speed is 10 Gb / s, the network switching device needs to be doubled (40 to 64), and when the signal transmission speed is 10 Gb / s, it is quadrupled (80 to 12).
8) network switching devices are required.

In such a multi-wavelength multiplex ring system, if the traffic is rescued not in units of STM-1 but in units of wavelengths, only one network switching function of each node is required for each wavelength. However, wavelength multiplexing ring
Conventionally, there is no device that realizes a network switching function in units of wavelengths in a network.

The present invention provides a wavelength division multiplexing network switching apparatus and a wavelength division multiplexing optical ring network system for realizing path switching in wavelength units in a ring optical network using a wavelength division multiplexing transmission method for transmitting a plurality of wavelengths. The purpose is to:

[0019]

According to the present invention, at the stage when wavelength-division multiplexed light is separated into each wavelength, the working / standby switching means comprises:
The active system and the standby system can be switched freely. As a result, for switching between the active system and the standby system, it is sufficient to prepare active / standby switching means for the number of wavelengths of the wavelength multiplexed light, and a system can be constructed at low cost.

Since the working / standby switching means corresponding to each wavelength has an optical switch network of the same configuration having working / add / drop ports, it is easy to change and add wavelength channels to be added / dropped. Become.

Each working / standby switching means is provided with means for simultaneously supplying signal light to both the working system and the protection system to which the signal light is to be transmitted, so that instantaneous switching to the working system restored from the protection system can be performed. Disconnection does not occur, and switching processing at both nodes at the time of switchback becomes easy.

Detecting signal frame overhead,
By providing a transmission terminal equipment for regenerating and repeating signal light, it is possible to easily monitor, notify, and detect the status of the transmission path, and to switch between the active system and the standby system by improving the quality of the optical signal. Become.

A second method for regenerating and repeating signal light on the wavelength multiplexing side.
By providing the above transmission terminal station device, it is possible to compensate for the deterioration of the signal light in the working / standby switching means.

By using one of the transmitted wavelengths for communication between the nodes, a larger amount of information can be exchanged between the nodes.

The working system and the protection system both comprise ring optical transmission lines, and the working system and the protection system each comprise two transmission media having different signal light transmission directions. Thus, for example, a four-fiber optical ring
Network reliability can be improved, and large-capacity data transmission can be realized by the wavelength division multiplexing transmission method.

[0026]

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

FIG. 1 is a schematic block diagram showing an embodiment of the present invention. For convenience of explanation, as shown in FIG. 2, it is assumed that three nodes A, B, and C are serially connected by a working line composed of a pair of optical fiber lines and a protection line composed of a pair of optical fiber lines. Assume that FIG. 1 illustrates the configuration of Node B.

A working line 30 and a protection line 32 are connected between the nodes A and B, and a working line 34 and a protection line 36 are connected between the nodes B and C. The working line 30 includes an optical fiber line 30a for transmitting an optical signal from the node A to the node B, and an optical fiber line 30b for transmitting an optical signal from the node B to the node A. The protection line 32 is an optical fiber line 32 for transmitting an optical signal from the node A to the node B.
a and an optical fiber line 32b for transmitting an optical signal from the node B to the node A.

The working line 34 includes an optical fiber line 34a for transmitting an optical signal from the node B to the node C, and an optical fiber line 34b for transmitting an optical signal from the node C to the node B. The protection line 36 includes an optical fiber line 36a for transmitting an optical signal from the node B to the node C, and an optical fiber line 36b for transmitting an optical signal from the node C to the node B.

In this embodiment, n wavelengths λ1 to λ
It is assumed that n signal lights are wavelength division multiplexed and transmitted. Regarding the transmission of information indicating the state of each node and the concession zone of the transmission path between adjacent nodes, there are a method of inserting into a signal in a time-division manner and a method of providing a dedicated wavelength. If one wavelength is dedicated to communication between nodes, more information can be exchanged between nodes.

The optical fiber line 30a of the working line 30 connected to the node A is connected to the input of the optical amplifier 40a, and the output of the optical amplifier 40a is connected to the input of the wavelength separation device 42a. The wavelength separation device 42a separates the output light of the optical amplifier 40a into respective wavelengths λ1 to λn, and separates the separated wavelengths λ1 to λn.
Are transmitted by the transmission terminal devices 44-1 to 44-n, respectively.
Is supplied to the optical input port X0.

The transmission terminal units 44-1 to 44-n convert the signal light input to the input port X0 into electric pulses once, convert the signal lights into optical pulses again, and output from the optical output port Y0 for regenerative relay. And the function of separating and extracting the over-header portion of the STM-16 signal from the input signal of the input port X0 and supplying it to the operation and maintenance controller 46. The transmission terminal devices 44-1 to 44-n further include an optical input port X
1 and an optical output port Y1, and the signal light input to the input port X1 is similarly reproduced and relayed and output from the optical output port Y1. These functions are the same as those of the transmission terminal devices 214 to 220 shown in FIG. Transmission terminal station 44-1
The signal wavelength (for example, 1.5
(μm band) is converted to 1.3 μm. This is because an inexpensive optical device can be obtained.

Working / standby switching circuits 48-1 to 48-n
Are the working lines 30,
34 and an optical circuit for switching between the protection lines 32 and 36, the optical input ports X0 to X3 and the optical output ports Y0 to Y3.
, And the switching between the active and the standby is controlled by the control device 46. The details of the working / standby switching circuits 48-1 to 48-n will be described later.

The optical output ports Y0 of the transmission terminal devices 44-1 to 44-n are respectively connected to a working / standby switching circuit 48-.
The optical output ports Y0 of the working / standby switching circuits 48-1 to 48-n are connected to the optical inputs X1 of the transmission terminal devices 50-1 to 50-n, respectively. I do. The transmission terminal devices 50-1 to 50-n have basically the same functions as the transmission terminal devices 44-1 to 44-n. Optical input port X of transmission terminal equipment 50-1 to 50-n
In the regenerative relay of the output light from 1 to the optical output port Y1, the wavelength conversion is performed in the opposite direction to the transmission terminal devices 44-1 to 44-n. That is, the signal wavelength is returned to the original wavelength.

The output light from the optical output port Y1 of the transmission terminal equipment 50-1 to 50-n is applied to the wavelength multiplexing device 52a, where it is multiplexed. The output of the wavelength multiplexing device 52a is connected to the input of the optical amplifier 54a, and the output of the optical amplifier 54a is connected to the optical fiber line 34a of the working line 34 connected to the node C.

The optical fiber line 34b of the working line 34 connected to the node C is connected to the input of the optical amplifier 54b, and the output of the optical amplifier 54b is connected to the input of the wavelength separation device 52b. The wavelength separation device 52b separates the output light of the optical amplifier 54b into each of the wavelengths λ1 to λn, and separates the separated wavelengths λ1 to λn.
Are respectively transmitted from the transmission terminal devices 50-1 to 50-n.
Is supplied to the optical input port X0. Transmission terminal device 50-
1 to 50-n, like the transmission terminal devices 44-1 to 44-n, temporarily convert signal light input to the input port X0 into electric pulses, and then convert the signal light into optical pulses again, and In addition to the output from Y0, the overhead signal is separated and extracted from the input signal of the input port X0 and supplied to the operation and maintenance controller 46.

The optical output ports Y0 of the transmission terminal units 50-1 to 50-n are respectively connected to the working / standby switching circuit 48-1.
To the optical input ports X1 of the active / standby switching circuits 48-1 to 48-n and the optical input ports X1 of the transmission terminal apparatuses 44-1 to 44-n, respectively.
Connect to 1.

The output light from the optical output port Y1 of each of the transmission terminal station devices 44-1 to 44-n is applied to the wavelength multiplexing device 42b, where it is multiplexed. The output of the wavelength multiplexing device 42b is connected to the input of the optical amplifier 40b, and the output of the optical amplifier 40b is connected to the optical fiber line 30b of the working line 30 connected to the node A.

The optical fiber line 32a of the protection line 32 connected to the node A is connected to the input of the optical amplifier 56a, and the output of the optical amplifier 56a is connected to the input of the wavelength separation device 58a. The wavelength separation device 58a separates the output light of the optical amplifier 56a into respective wavelengths λ1 to λn, and separates the separated wavelengths λ1 to λn.
Are transmitted by the transmission terminal equipment 60-1 to 60-n, respectively.
Is supplied to the optical input port X0. Transmission terminal device 60-
1 to 60-n have completely the same functions as the transmission terminal devices 44-1 to 44-n.

The optical output ports Y0 of the transmission terminal equipment 60-1 to 60-n are respectively connected to the working / standby switching circuit 48-1.
To the optical input ports X2 of the working / standby switching circuits 48-1 to 48-n, respectively, to the optical input ports X1 of the transmission terminal devices 62-1 to 62-n. Connecting. The transmission terminal devices 62-1 to 62-n have the same functions as the transmission terminal devices 50-1 to 50-n.

The output light from the optical output port Y1 of each of the transmission terminal devices 62-1 to 62-n is applied to a wavelength multiplexing device 64a, where it is multiplexed. The output of the wavelength multiplexing device 64a is connected to the input of the optical amplifier 66a, and the output of the optical amplifier 66a is connected to the optical fiber line 36a of the protection line 36 connected to the node C.

The optical fiber line 36b of the protection line 36 connected to the node C is connected to the input of the optical amplifier 66b, and the output of the optical amplifier 66b is connected to the input of the wavelength separation device 64b. The wavelength separating device 64b separates the output light of the optical amplifier 66b into each of the wavelengths λ1 to λn, and separates the separated wavelengths λ1 to λn.
Are transmitted by the transmission terminal devices 62-1 to 62-n, respectively.
Is supplied to the optical input port X0. Transmission terminal device 62-
1 to 62-n, like the transmission terminal devices 60-1 to 60-n, convert the signal light input to the input port X0 into an electrical pulse once, and then convert the signal light into an optical pulse again to generate an optical output port. In addition to the output from Y0, the overhead signal is separated and extracted from the input signal of the input port X0 and supplied to the operation and maintenance controller 46.

Each of the optical output ports Y0 of the transmission terminal devices 62-1 to 62-n is connected to a working / standby switching circuit 48-1.
To the optical input ports X3 of the working / standby switching circuits 48-1 to 48-n, and the optical input ports X3 of the transmission terminal devices 60-1 to 60-n.
Connect to 1.

The output light from the optical output port Y1 of each of the transmission terminal equipments 60-1 to 60-n is applied to the wavelength multiplexing device 58b, where it is multiplexed. The output of the wavelength multiplexing device 58b is connected to the input of the optical amplifier 56b, and the output of the optical amplifier 56b is connected to the optical fiber line 32b of the protection line 32 connected to the node A.

In this embodiment, the wavelength separation devices 42a, 52
b, 58a, 64b and wavelength multiplexing devices 42b, 52a,
Although 58b and 64a are composed of an arrayed waveguide grating, it is clear that the wavelength multiplexing devices 42b, 52a, 58b and 64a may be addition devices that simply add a plurality of input lights.

FIG. 3 is a schematic block diagram of a working / standby switching circuit (for example, 48-1) for a wavelength dropped at the node B (hereinafter, referred to as a dropped wavelength, for example, λ1). 70 is eight optical input ports X0
X7 and eight optical output ports Y0 to Y7. The optical input ports X0, X1, X2, X3 of the optical switch network 70 are respectively optical input ports X0, X1, X2, of the working / standby switching circuit 48-1.
X3 and the optical output port Y of the optical switch network 70.
0, Y1, Y2, and Y3 are respectively connected to the optical output ports Y0, Y1, Y2, and Y3 of the working / standby switching circuit 48-1.

The optical input port X4 of the optical switch network 70
The optical output port Y4 is connected to a time division multiplexer / demultiplexer 74 via a high-speed electrical / optical interface 72, and the optical input port X5 and the optical output port Y5 are connected to a time division multiplexer / demultiplexer via a high speed electrical / optical interface 76. 78, an optical input port X6 and an optical output port Y6 are connected to a time division multiplexing / demultiplexing device 82 via a high-speed electrical / optical interface 80, and an optical input port X7 and an optical output port Y
7 is connected to a time-division multiplexing / demultiplexing device 86 via a high-speed electrical / optical interface 84.

High-speed electrical / optical interface 72, 7
6,80,84 are all STM-16 (2.48G
It is composed of a laser element that converts an electric signal into an optical signal and a light receiving element that converts an optical signal into an electric signal. Time division demultiplexing devices 74, 78, 8
2, 86 are connected to a plurality of (up to 16) low-speed interfaces respectively connected to low-speed transmission lines such as domestic terrestrial transmission systems, and electric signals from these low-speed interfaces (for example, STM-1 (156 Mbps)) Are multiplexed on the time axis and supplied to the high-speed electrical / optical interfaces 72, 76, 80, 84, respectively.
ST from optical interface 72, 76, 80, 84
The electrical signal of M-16 is separated into STM-1 on the time axis and supplied to each low-speed interface.

The high-speed electrical / optical interface 72 is provided for adding / dropping to the working line 30,
The high-speed electrical / optical interface 76 is provided for adding / dropping to the protection line 32, and the high-speed electrical / optical interface 80 is provided for adding / dropping to the working line 34.
The high-speed electrical / optical interface 84 is provided for dropping and adding / dropping to the protection line 36.

FIG. 4 is a schematic block diagram of the optical switch network 70. Ports the same as those in FIG. 3 are denoted by the same reference numerals. The optical switch network 70 includes twelve 2 × 2 optical switches 110 to 132 and four optical fiber branch couplers 134, 136, 138, and 140. The optical switches 110 to 132 include a through connection in which the port X0 is connected to the port Y0 and a connection between the port X1 and the port Y1, a connection between the port X0 and the port Y1, and a connection in the port X0.
The cross connection between the port 1 and the port Y0 can be selected from outside (specifically, the control device 46).

The connection between the optical switches 110 to 132 and the optical fiber branch couplers 134 to 140 will be described. The optical input port X0 of the optical switch network 70 is connected to the port X0 of the optical switch 110, and the optical input port X2 of the optical switch network 70 is connected to the port X1 of the optical switch 110.
The port Y0 of the optical switch 110 is connected to the port X1 of the optical switch 118, and the port Y1 of the optical switch 110 is connected to the port X1 of the optical switch 130. The optical input port X6 of the optical switch network 70 connects to the port X0 of the optical switch 118, and the port Y0 of the optical switch 118 connects to the port X0 of the optical switch 120. Optical switch 11
The output light from the port Y1 of the optical fiber 8
4, one is applied to the port X0 of the optical switch 122, and the other is applied to the optical fiber branching coupler 13
6 further divides it into two. Optical fiber branch coupler 1
One of the split lights 36 enters the port X0 of the optical switch 114, and the other split light enters the optical output port Y0 of the optical switch network 70.

The optical input port X5 of the optical switch network 70
Is connected to the port X0 of the optical switch 124, and the port Y0 of the optical switch 124 is connected to the port X1 of the optical switch 120.
, And the port Y1 of the optical switch 124 is connected to the port X1 of the optical switch 122. The port Y0 of the optical switch 120 connects to the optical output port Y4 of the optical switch network 70, and the port Y1 of the optical switch 120 connects to the optical output port Y7 of the optical switch network 70. Optical switch 1
The port Y1 of 22 is connected to the port X0 of the optical switch 112. Port Y0 of optical switch 112 connects to optical output port Y3 of optical switch network 70.

The optical input port X1 of the optical switch network 70
Is connected to the port X0 of the optical switch 116, and the optical input port X3 of the optical switch network 70 is connected to the port X1 of the optical switch 116. The port Y0 of the optical switch 116 is connected to the port X1 of the optical switch 126, and the optical switch 1
The 16 ports Y1 are connected to the port X1 of the optical switch 124. The optical input port X4 of the optical switch network 70 is connected to the port X0 of the optical switch 126, and the optical switch 12
The port Y0 of port 6 is connected to the port X0 of the optical switch 128. The output light of the port Y1 of the optical switch 126 is split into two by the optical fiber branch coupler 138, one is applied to the port X1 of the optical switch 132, and the other is further split into two by the optical fiber branch coupler 140. One split light of the optical fiber branch coupler 140 is input to the port X1 of the optical switch 112, and the other split light is input to the optical output port Y1 of the optical switch network 70.

The optical input port X7 of the optical switch network 70
Is connected to the port X0 of the optical switch 130, and the port Y0 of the optical switch 130 is connected to the port X1 of the optical switch 128.
And the port Y1 of the optical switch 130 is connected to the port X1 of the optical switch 132. Port Y0 of optical switch 128 connects to optical output port Y6 of optical switch network 70, and port Y1 of optical switch 128 connects to optical output port Y5 of optical switch network 70. Optical switch 1
The 32 port Y1 is connected to the port X1 of the optical switch 114. The port Y1 of the optical switch 114 connects to the optical output port Y2 of the optical switch network 70.

A working / standby switching circuit (for example, 48-2 to 48-n) for a wavelength that is not added / dropped at the node B (hereinafter referred to as a through wavelength) is different from the configuration shown in FIG. , 76,80,
84 and the time division multiplexing / demultiplexing devices 74, 78, 82, 86 are eliminated. That is, the working / standby switching circuits 48-2 to 48- for wavelengths not dropped at the node B.
As shown in FIG. 5, n is composed of only the optical switch network 70a having exactly the same configuration as the optical switch network 70. Optical switches 110a-13 in optical switch network 70a
2a and optical fiber branch couplers 134a, 136a,
138a and 140a respectively correspond to the optical switch network 7
0 corresponds to the optical switches 110 to 132 and the optical fiber branch couplers 134, 136, 138, and 140.

The optical switch network 70 (and 70a) having the same configuration is used regardless of whether add / drop is performed or not.
The use of the spare switching circuits 48-1 to 48-n has the following advantages. That is, if you want to change or add a wavelength channel to be added / dropped afterwards,
The high-speed electrical / optical interfaces 72, 76, 80, 84 and the time-division multiplexing / demultiplexing device 74,
It is only necessary to connect 78, 82, 86. Further, since all the working / standby switching circuits 48-1 to 48-n have the same optical input / output characteristics regardless of the presence / absence of add / drop, transmission conditions are simplified. A single optical switch network 70 (and 70a), with or without add / drop
Therefore, the burden on the transmission system design is small, and the burden on maintenance is also small.

The operation of this embodiment will be described. Working line 30
The signal light transmitted from the node A via the optical fiber line 30a is optically amplified by the optical amplifier 40a, and then separated by the wavelength separation device 42a into each of the wavelengths λ1 to λn. Transmission terminal equipment 44-1
~ 44-n. Each transmission terminal station device 44-1 to 4-4
4-n reproduces and repeats the signal light input to the input port X0 and supplies the signal light from the optical output port Y0 to the optical input ports X0 of the working / standby switching circuits 48-1 to 48-n. And extracts the overheader from the input signal and supplies it to the controller 46. With the latter function, it is possible to know the presence / absence and position of a line failure that may occur in the working line 30 and the line ahead thereof, for example, a line connection failure, a line break, a failure of the optical amplifier, and the like.

The optical fiber line 34 of the working line 34
The optical signal transmitted from the node C via the optical amplifier b is optically amplified by the optical amplifier 54b, and then separated by the wavelength separating device 52b into each of the wavelengths λ1 to λn. Applied to the devices 50-1 to 50-n. Each of the transmission terminal devices 50-1 to 50-n regenerates and repeats the signal light input to the input port X0, and outputs the working / standby switching circuits 48-1 to 48-n from the optical output port Y0.
To the optical input port X1, and the input port X0
The SOH is separated and extracted from the input signal of the control unit 46 and supplied to the control unit 46. With the latter function, it is possible to know the presence / absence and location of a line failure that may occur in the working line 34 and the line ahead of it.

Normally, signals of low importance, which are not rescued even when a failure occurs, flow through the protection lines 32 and 36.
The flow is basically the same as that of the working lines 30 and 34. That is, the signal light transmitted from the node A via the optical fiber line 32a of the protection line 32 is
After being optically amplified by a, the wavelengths are separated into wavelengths λ1 to λn by the wavelength separation device 58a and applied to the transmission terminal devices 60-1 to 60-n corresponding to the wavelengths λ1 to λn. Each of the transmission terminal devices 60-1 to 60-n regenerates and repeats the signal light input to the input port X0, and
0 to the optical input port X2 of each of the working / standby switching circuits 48-1 to 48-n, and separates and extracts the overheader from the input signal of the input port X0 to control the controller 46.
To supply. With the latter function, the presence / absence and location of a line failure that may occur in the protection line 32 and the line ahead of it can be known.

The optical signal transmitted from the node C via the optical fiber line 36b of the protection line 36 is
After being optically amplified by the wavelength separation device 64b, the light is separated into wavelengths λ1 to λn by the wavelength separation device 64b and applied to the transmission terminal devices 62-1 to 62-n corresponding to the wavelengths λ1 to λn. Each of the transmission terminal apparatuses 62-1 to 62-n regenerates and repeats the signal light input to the input port X0, and outputs the signal light to the optical output port Y0.
Supplies to the optical input port X3 of the working / standby switching circuit 48-1 to 48-n, separates and extracts the overheader from the input signal of the input port X0, and supplies it to the control device 46. With the latter function, the presence / absence and location of a line failure that can occur in the protection line 34 and the line ahead of it can be known.

As will be described later in detail, if there is no failure in the working lines 30 and 34, the working / standby switching circuit 48-
The 2-48-n (optical switch network 70a thereof) has substantially the same through state as the state where the optical input ports X0, X1, X2, and X3 are connected to the optical output ports Y0, Y1, Y2, and Y3, respectively. . In the working / standby switching circuit 48-1 (the optical switch network 70 of the working / protection switching circuit 48-1) which handles the signal light of the wavelength to be added / dropped at the node B (hereinafter referred to as add / drop wavelength) λ1, the signal from the working lines 30 and 34 is used. The light is dropped and a new signal light is added on the working lines 30 and 34. Similarly, for the protection lines 32 and 36, the signal lights from the working lines 32 and 36 are dropped, and new signal lights are added to the protection lines 32 and 36. Working line 3
4 cannot be used, the working / standby switching circuit 48
The optical switch networks 70 and 70a of -1 to 48-n are switched to use the protection line 36 instead of the working line 34, and when both the working line 34 and the protection line 36 cannot be used (cable breakage or the like). Has a working line 30
Is transmitted to the protection line 32.

Working / standby switching circuits 48-1 to 48-n
The signal light output from the optical output port Y0 is applied to the optical input port X1 of each of the transmission terminal equipment 50-1 to 50-n, where the signal light is regenerated and relayed from the optical output port Y1 to the wavelength multiplexing device 52a. Applied. Wavelength multiplexing device 52a
Are the wavelengths λ1 to λ1 from the transmission terminal devices 50-1 to 50-n.
λn signal light is wavelength-multiplexed. The output light of the wavelength multiplexing device 52a is optically amplified by the optical amplifier 54a, and
4 is sent to the optical fiber line 34a. The signal lights output from the optical output ports Y1 of the working / standby switching circuits 48-1 to 48-n are transmitted to the transmission terminal devices 44-1 to 4-4, respectively.
4-n is applied to the optical input port X1, where it is regenerated and relayed and applied from the optical output port Y1 to the wavelength multiplexing device 42b. The wavelength multiplexing device 42b includes a transmission terminal device 44-1.
The signal light of wavelengths λ1 to λn from ４４44-n is wavelength-multiplexed. The output light of the wavelength multiplexing device 42b is optically amplified by the optical amplifier 40b, and the optical fiber line 30b of the working line 30 is used.
Sent to

Working / standby switching circuits 48-1 to 48-n
The signal light output from the optical output port Y2 is applied to the optical input port X1 of each of the transmission terminal devices 62-1 to 62-n, where the signal light is regenerated and relayed to the wavelength multiplexing device 64a from the optical output port Y1. Applied. Wavelength multiplexing device 64a
Are the wavelengths λ1 to λ1 from the transmission terminal devices 62-1 to 62-n.
λn signal light is wavelength-multiplexed. The output light of the wavelength multiplexing device 64a is optically amplified by the optical amplifier 66a, and
6 is transmitted to the optical fiber line 36a. The signal light output from the optical output port Y3 of the working / standby switching circuit 48-1 to 48-n is transmitted to the transmission terminal equipment 60-1 to 60-6, respectively.
It is applied to the optical input port X1 of 0-n, where it is regenerated and relayed and applied from the optical output port Y1 to the wavelength multiplexing device 58b. The wavelength multiplexing device 58b is connected to the transmission terminal device 60-1.
Λ-λn are multiplexed. The output light of the wavelength multiplexing device 58b is optically amplified by the optical amplifier 56b, and the optical fiber line 32b of the protection line 32
Sent to

First, the operation of the optical switch networks 70 and 70a when there is no failure in the working lines 30 and 34 will be described.

In the optical switch network 70 of the working / standby switching circuit 48-1 corresponding to the add / drop wavelength λ1 of the node B, as shown in FIG.
4, 126, 130 are cross-connected, and the other optical switches 110, 112, 114, 116, 120,
122, 128 and 132 are through connections.

Thus, the input light of the optical input port X0 of the optical switch network 70 (that is, the optical input port X0 of the working / standby switching circuit 48-1) is transmitted from the port X0 of the optical switch 110 to the port Y0, 118 port X
1 to port Y0 and port X0 of optical switch 120
From the optical output port Y4 of the optical switch network 70 to the high-speed electrical / optical interface 72.
Supplied to That is, the optical fiber line 3 of the working line 30
This means that the signal light having the wavelength λ1 from 0a is dropped on the high-speed electrical / optical interface 72.

The signal light input from the high-speed electrical / optical interface 80 to the optical input port X6 of the optical switch network 70 is transmitted from the port X0 to the port Y of the optical switch 118.
1 and the optical fiber branch couplers 134 and 136, and the optical output port Y0 of the optical switch network 70, ie,
It is output from the optical output port Y0 of the working / standby switching circuit 48-1. Therefore, the high-speed electrical / optical interface 8
0 is supplied to the optical input port X1 of the transmission terminal device 50-1, and a new signal light is added to the optical fiber line 34a of the working line 34. Become.

The input light of the optical input port X1 of the optical switch network 70 (that is, the input light of the optical input port X1 of the working / standby switching circuit 48-1) is input from the port X0 of the optical switch 116 to the port Y0, Port X1 to port Y0 of optical switch 126 and port X of optical switch 128
0 to the port Y0, and from the optical output port Y6 of the optical switch network 70 to the high-speed electrical / optical interface 8.
0 is supplied. That is, the signal light of the wavelength λ1 from the optical fiber line 34b of the working line 34 is dropped to the high-speed electrical / optical interface 80.

The signal light input from the high-speed electrical / optical interface 72 to the optical input port X4 of the optical switch network 70 is transmitted from the port X0 to the port Y of the optical switch 126.
1 and the optical fiber branch couplers 138 and 140, and are output from the optical output port Y1 of the optical switch network 70, that is, the optical output port Y1 of the working / standby switching circuit 48-1. As a result, the signal light output from the high-speed electrical / optical interface 72 is supplied to the optical input port X1 of the transmission terminal device 44-1 and the new signal light is transmitted to the optical fiber line 30b of the working line 30. Will be added to.

The optical input port X2 of the optical switch network 70
(Optical input port X2 of working / standby switching circuit 48-1)
Is transmitted from port X1 to port Y1 of optical switch 110, from port X1 to port Y0 of optical switch 130, and from port X1 to port Y1 of optical switch 128, and from optical output port Y5 of optical switch network 70. It is supplied to the high-speed electrical / optical interface 76. As a result, the signal light having the wavelength λ1 from the optical fiber line 32a of the protection line 32 is dropped to the high-speed electrical / optical interface 76.

The signal light input from the high-speed electrical / optical interface 84 to the optical input port X7 of the optical switch network 70 is transmitted from the port X0 to the port Y of the optical switch 130.
1, transmitted from the port X1 to the port Y1 of the optical switch 132 and from the port X1 to the port Y1 of the optical switch 114, and transmitted to the optical output port Y2 of the optical switch network 70, that is, the light of the working / standby switching circuit 48-1. Output port Y2
Output from Therefore, the signal light output from the high-speed electrical / optical interface 84 is added to the optical fiber line 36a of the protection line 36.

The optical input port X3 of the optical switch network 70
(Optical input port X3 of working / standby switching circuit 48-1)
Are input from the port X1 to the port Y1 of the optical switch 116, the port X1 to the port Y0 of the optical switch 124,
And transmitted from the port X1 of the optical switch 120 to the port Y1, and supplied from the optical output port Y7 of the optical switch network 70 to the high-speed electrical / optical interface 84. As a result, the signal light of wavelength λ1 from the optical fiber line 36b of the protection line 36 is transmitted to the high-speed electrical / optical interface 84.
Will be dropped.

The signal light input from the high-speed electrical / optical interface 76 to the optical input port X5 of the optical switch network 70 is transmitted from the port X0 to the port Y of the optical switch 124.
1, transmitted from the port X1 to the port Y1 of the optical switch 122 and from the port X0 to the port Y0 of the optical switch 112, and transmitted to the optical output port Y3 of the optical switch network 70, that is, the light of the working / standby switching circuit 48-1. Output port Y3
Output from Therefore, the signal light output from the high-speed electrical / optical interface 76 is added to the optical fiber line 32b of the protection line 32.

As described above, when the working lines 30 and 34 are normal, the protection lines 32 and 36 can be added / dropped, and signals can be transmitted. However, as will be described later, no relief is provided for a failure.

When both the working lines 30 and 34 are normal, the working / standby switching circuit 4 corresponding to the through wavelength of the node B
8-2 to 48-n in the optical switch network 70a, FIG.
As shown in (1), all the optical switches 110a to 132a are in a through connection. In this connection, the optical switch network 7
The signal light input to the optical input ports X0, X1, X2, and X3a (ie, the optical input ports X0, X1, X2, and X3 of the working / standby switching circuits 48-2 to 48-n) is converted into an optical switch network. 70a optical output ports Y0, Y1, Y2, Y
3 (that is, output from the optical output ports Y0, Y1, Y2, and Y3 of the working / standby switching circuits 48-2 to 48-n).
After all, the optical fiber line 30 of the working line 30 is substantially
a and 30b are the optical fiber lines 3 of the working line 34, respectively.
4a and 34b, the optical fiber lines 32a and 32b of the protection line 32 are connected to the optical fiber lines 36a and 36b of the protection line 36, respectively.

Next, a case where a failure occurs in the working line 34 will be described. In this case, from the working line 34 to the protection line 36
To the control device 46
Are the optical switches 11 of the optical switch networks 70 and 70a.
4, 116; 114a and 116a are switched to cross connection. The connection of the optical switch network 70 is shown in FIG. 8, and the connection of the optical switch network 70a is shown in FIG.

As shown in FIG. 8, the optical switch network 70
In FIG. 6, the signal light (wavelength λ1) input from the optical fiber line 30a of the working line 30 and input to the optical input port X0 is shown in FIG.
In the same manner as in the case of
It is supplied to the optical interface 72. That is, the signal light of the wavelength λ1 from the optical fiber line 30a of the working line 30 is dropped to the high-speed electrical / optical interface 72.

The signal light input from the high-speed electrical / optical interface 80 to the optical input port X6 of the optical switch network 70 is transmitted from the port X0 to the port Y of the optical switch 118.
1 and the optical fiber branch couplers 134 and 136, and from the port X0 of the optical switch 114 to the port Y0, and the optical output port Y2 of the optical switch network 70, that is, the working / standby switching circuit 48-1. Optical output port Y2
Output from Therefore, the signal light output from the high-speed electrical / optical interface 80 is added to the optical fiber line 36a of the protection line 36.

The input light of the optical input port X3 of the working / standby switching circuit 48-1 (the signal light of the wavelength λ1 from the optical fiber line 36b of the protection line 36) is transmitted to the optical input port X3 of the optical switch network 70. From the port X1 to the port Y0 of the optical switch 116, from the port X1 to the port Y0 of the optical switch 126, and from the port X0 to the port Y0 of the optical switch 128, and from the optical output port Y6 of the optical switch network 70. It is supplied to the optical interface 80. As a result, the signal light of the wavelength λ1 from the optical fiber line 36b of the protection line 36 is dropped to the high-speed electrical / optical interface 80.

The signal light input from the high-speed electrical / optical interface 72 to the optical input port X4 of the optical switch network 70 is transmitted from the port X0 to the port Y1 of the optical switch 126 and to the optical fiber branch in the same manner as in FIG. Coupler 1
38 and 140, and output from the optical output port Y1 of the optical switch network 70, that is, the optical output port Y1 of the working / standby switching circuit 48-1. Thus, the signal light output from the high-speed electrical / optical interface 72 is added to the optical fiber line 30b of the working line 30.

The optical switch network 70a shown in FIG. 9 will be described. In the optical switch network 70a, the optical switch 118
a and 126a are through connections. Therefore, the input light of the optical input port X0 of the optical switch network 70a (the signal light from the optical fiber line 30a of the working line 30) is transmitted from the optical output port Y2 to the optical fiber line 36 of the protection line 36.
a, and the input light of the optical input port X3 of the optical switch network 70a (signal light from the optical fiber line 36b of the protection line 36) is transmitted from the optical output port Y1 to the optical fiber line 36b of the working line 36. You. That is, the working line 3
0 and the protection line 36 are connected.

In the configurations shown in FIGS. 8 and 9, the working line 30 and the protection line 36 are connected to each other, and the wavelength λ1 can be dropped in both directions. The signal light of the wavelength λ1 from the optical fiber line 32a of the protection line 32 (that is, the signal addressed to the node B) can be dropped, and the signal addressed to another node can be transmitted to the optical fiber line 32b of the protection line 32.

The optical switch networks 70 and 70a of this embodiment
136, the beam splitters 136, 140;
a, 140a, the same signal light output from the optical output port Y2 is transmitted to the optical switch network 70.
Is also output from the light output port Y0. As a result, when the working line 34 is restored, the same signal light naturally flows through both the working line 34 and the protection line 36, and there is an advantage that instantaneous interruption does not occur when switching back from the protection line 36 to the working line 34. There is.

A failure occurs in the working line 30 and the protection line 32
It is clear that the optical switches 110 and 112; 110a and 112a should be changed to the cross connection for the connection in FIGS. With this change,
The working line 34 and the protection line 32 are connected, and the channel with the add / drop wavelength λ1 can add / drop in either direction.

Next, an operation when a cable failure occurs, for example, when both the working line 34 and the protection line 36 become unusable will be described. The connection of the optical switch network 70 at this time is shown in FIG. 10, and the connection of the optical switch network 70a is shown in FIG. The controller 46 controls the optical switches 118, 122, 126, 128, 1 of the optical switch network 70.
30 is cross-connected, and the other optical switches 110, 1
12, 114, 116, 120, 124, and 132 are connected in a through connection, and the optical switch 1
22a is cross-connected, and the other optical switch 110a
To 120a and 124a to 132a are connected through.

As shown in FIG. 10, the optical switch network 7
0, the signal light (wavelength λ1) input from the optical fiber line 30a of the working line 30 to the optical input port X0 is transmitted from the optical output port Y4 to the high-speed electrical / optical interface 72 in the same manner as in FIG. Supplied. That is, the signal light of the wavelength λ1 from the optical fiber line 30a of the working line 30 is dropped to the high-speed electrical / optical interface 72.

The signal light input from the high-speed electrical / optical interface 80 to the optical input port X6 of the optical switch network 70 is transmitted from the port X0 to the port Y of the optical switch 118.
1. Optical fiber branch coupler 134, optical switch 122
From the port X0 to the port Y1 and from the port X0 to the port Y0 of the optical switch 112, and output from the optical output port Y3 of the optical switch network 70, that is, the optical output port Y3 of the working / standby switching circuit 48-1. Is done. Therefore, the signal light output from the high-speed electrical / optical interface 80 is added to the optical fiber line 32b of the protection line 32.

The input light of the optical input port X2 of the working / standby switching circuit 48-1 (signal light of the wavelength λ1 from the optical fiber line 32a of the protection line 32) is input to the optical input port X2 of the optical switch network 70. From the port X1 to the port Y1 of the optical switch 110, from the port X1 to the port Y0 of the optical switch 130, and from the port X1 to the port Y0 of the optical switch 128, and from the optical output port Y6 of the optical switch network 70. It is supplied to the optical interface 80. As a result, the signal light having the wavelength λ1 from the optical fiber line 32a of the protection line 32 is dropped to the high-speed electrical / optical interface 80.

The signal light input from the high-speed electrical / optical interface 72 to the optical input port X4 of the optical switch network 70 is transmitted from the port X0 to the port Y1 of the optical switch 126 and to the optical fiber branch, as in the case of FIG. Coupler 1
38 and 140, and output from the optical output port Y1 of the optical switch network 70, that is, the optical output port Y1 of the working / standby switching circuit 48-1. Thus, the signal light output from the high-speed electrical / optical interface 72 is added to the optical fiber line 30b of the working line 30.

The optical switch network 70a shown in FIG. 11 will be described. The input light of the optical input port X0 of the optical switch network 70a (the signal light from the optical fiber line 30a of the working line 30) is transmitted from the port X0 to the port Y0 of the optical switch 110a and from the port X1 to the port Y of the optical switch 118a.
1, port X0 to port Y1 of the optical switch 122a,
And from the port X0 to the port Y0 of the optical switch 112a, and to the optical output port Y3 of the optical switch network 70a.
Is sent to the optical fiber line 32b of the protection line 32. Accordingly, the optical fiber line 30a of the working line 30 and the optical fiber line 32a of the protection line 32 are connected. The signal of the through wavelength from the optical fiber line 32a of the protection line 32 is discarded because it is not forwarded to the optical fiber line 30a of the working line 30 in the optical switch network 70a. However, the signal light of wavelength λ1 from the optical fiber line 32a of the protection line 32 can be received by the high-speed electrical / optical interface 80 via the optical switch network 70, and the node B A can communicate.

In the optical switch network 70, the optical switch 1
20 and 128 may be omitted, and a switch circuit for performing the same switching at the electric stage may be provided instead. In this case, the optical switch network 70a is also changed to a similar configuration in order to maintain the sameness. Optical switches 110, 112, 1
In place of the optical switches 14 and 116, the same operation and effect can be obtained by disposing optical switches having the same operation outside the wavelength demultiplexers 42a, 52b, 58a and 64b and the wavelength multiplexing devices 42b, 52a, 58b and 64a. Can be.

FIG. 12 is a schematic block diagram of an optical switch network 70b in which the optical switch network 70 is modified. The configuration of the optical switch network 70a is also changed to the same configuration as the optical switch network 70b. FIG.
Indicates a state in which the working lines 30 and 32 are connected to each other.

In the modified optical switch network 70b,
Optical fiber branch coupler 13 of optical switch network 70
0, 132, 134, and 136 have been removed, and 'b' has been added to the code of the optical switch whose connection relation has been changed. That is, the port Y0 of the optical switch 122b is connected to the port X0 of the optical switch 114b,
b output port Y0 connects to optical output port Y0 of optical switch network 70b. Port Y of optical switch 132b
0 connects to port X0 of optical switch 112b, and port Y1 of optical switch 112b connects to optical output port Y1 of optical switch network 70b.

In the configuration shown in FIG.
Since the same signal light does not flow through protection lines 32 and 36 and working lines 30 and 34 when switching back from network 6 to working lines 30 and 34, it is important to coordinate circuit switching between related nodes. become.

In the inter-node communication of the failure information and the switching control signal required for switching the working / protection network, for example, a method of providing a dedicated wavelength to perform communication using the dedicated wavelength and a method of adding a dedicated wavelength to a signal frame of a transmission signal are used. There is a method of providing a channel between nodes in the overhead signal. In the latter case,
After separating each wavelength of the signal light, each signal is electrically terminated, and the overhead signal added to the signal frame is separated and extracted.

One of the wavelengths transmitting the wavelength multiplexing ring optical network system may be used for inter-node communication. In that case, the signal light of that wavelength is set to be addable / droppable at all nodes.

Although the wavelength multiplexing ring optical network system has been described in detail as an example, the configuration itself of the working / standby switching device shown in FIG. 1 is not limited to the ring optical network, but can be used in various optical transmission modes. Applicable to

[0098]

As can be easily understood from the above description, according to the present invention, it becomes possible to rescue traffic for each wavelength in the wavelength division multiplexing transmission system.

Since it is only necessary to provide the number of active / standby switching means corresponding to the number of multiplexed wavelengths, even if the number of multiplexed wavelengths increases, it is possible to cope easily and at low cost.

By providing the same optical switch network for each of the add / drop wavelength and the through wavelength, it is possible to easily respond to the subsequent change / addition of the add / drop wavelength.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of an embodiment of the present invention.

FIG. 2 is an explanatory connection example of the optical ring network of the embodiment.

FIG. 3 is a schematic block diagram of a working / standby switching circuit 48-1 for add / drop wavelengths.

FIG. 4 is a schematic configuration block diagram of an optical switch network 70;

FIG. 5 is a working / standby switching circuit 4 for a through wavelength.
It is a schematic block diagram of 8-1.

FIG. 6 is a connection diagram of the optical switch network 70 in a normal state.

FIG. 7 is a connection diagram of the optical switch network 70a in a normal state.

8 is a connection diagram of the optical switch network 70 when a failure occurs in the working line 34. FIG.

FIG. 9 is a connection diagram of the optical switch network 70a when a failure occurs in the working line 34;

FIG. 10 is a connection diagram of the optical switch network 70 when both the working line 34 and the protection line 36 are disabled.

FIG. 11 is a connection diagram of the optical switch network 70a when both the working line 34 and the protection line 36 become unavailable.

FIG. 12 is a schematic configuration block diagram of a modified example of the optical switch network 70;

FIG. 13 is a schematic configuration block diagram of a conventional network switching device.

FIG. 14 is a schematic configuration diagram of a ring optical network system including four fiber rings.

FIG. 15 is a connection diagram in a state where a failure has occurred in a working transmission path between a node 1 and a node 2;

FIG. 16 is a connection diagram when a failure occurs in an optical fiber cable between nodes 1 and 2;

FIG. 17 is an example of a frame structure of an STM-16 signal.

FIG. 18 is a schematic block diagram of a conventional network switching system when the signal transmission speed is 5 Gb / s.

FIG. 19 is a schematic configuration block diagram of transmission terminal devices 214 to 220.

[Explanation of symbols]

10, 12: high-speed interface 14, 16: high-speed interface 18: low-speed interface 20: transmitting / receiving device 22: add / drop device 30: working line 30a, 30b: optical fiber line 32: protection line 32a, 32b: optical fiber line 34: Working line 34a, 34b: Optical fiber line 36: Protection line 36a, 36b: Optical fiber line 40a, 40b: Optical amplifier 42a: Wavelength demultiplexer 42b: Wavelength multiplexing device 44-1 to 44-n: Transmission terminal station device 46: Control devices 48-1 to 48-n: working / standby switching circuits 50-1 to 50-n: transmission terminal device 52a: wavelength multiplexing device 52b: wavelength demultiplexing devices 54a, 54b: optical amplifiers 56a, 56b: optical amplifier 58a : Wavelength separation device 58b: Wavelength multiplexing device 60-1 to 60-n: Transmission terminal station device 2-1 to 62-n: Transmission terminal device 64a: Wavelength multiplexing device 64b: Wavelength demultiplexing device 66a, 66b: Optical amplifier 70, 70a, 70b: Optical switch network 72: High-speed electric / optical interface 74: Time division multiplexing Demultiplexer 76: High-speed electrical / optical interface 78: Time-division multiplex / demultiplexer 80: High-speed electrical / optical interface 82: Time-division multiplex / demultiplexer 84: High-speed electrical / optical interface 86: Time-division multiplex / demultiplexer 110-132: Optical switch 110a-132a: Optical switches 134, 136, 138, 140: Optical fiber branch couplers 134a, 136a, 138a, 140a: Optical fiber branch couplers 112b, 114b 122b, 132b: Optical switches 210, 212: Network switching devices 214-220: Transmission Terminal device 222, 2 4: light receiving device 226, 228: error correction coding circuit 230: multiplexing device 232: light emitting device 234: optical amplifier 236: optical amplifier 238: light receiving device 240: separating device 242, 244: error correcting circuit 246, 248: light emitting apparatus

[Procedure amendment]

[Submission date] January 7, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI H04Q 11/04 H04Q 11/04 M (72) Inventor Naoki Kobayashi 2-3-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo International Telegraph and Telephone Corporation (72) Inventor Hitoshi Takahira 2-3-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo International Telegraph and Telephone Corporation (72) Inventor Takatomi Kabashima 2-3-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo International Telephone Inside the corporation

Claims (9)

[Claims] 1. A multiplexing network switching device for switching to a standby system in the event of a failure in an active system in a wavelength division multiplexing transmission system, comprising: a working system wavelength separating means for wavelength-demultiplexing wavelength-multiplexed light input from the active system; Standby wavelength separation means for wavelength-demultiplexing wavelength-multiplexed light input from the system, working wavelength-division multiplexing means for wavelength-multiplexing signal light of each wavelength to be transmitted to the working system, and each wavelength to be transmitted to the protection system Protection wavelength multiplexing means for wavelength multiplexing the signal light, and a predetermined number of working / protection switching means corresponding to the number of wavelengths to be transmitted, each of which is the working wavelength separation means and the protection wavelength separation means. Signal light of a predetermined wavelength from
A wavelength-division multiplexing network switching device comprising: a working / standby switching means for selectively supplying at least one of the working wavelength multiplexing means and the protection wavelength multiplexing means. 2. The wavelength-division multiplexing network switching apparatus according to claim 1, wherein each of the working / standby switching means includes an optical switch network having the same configuration and having a working add / drop port. 3. The wavelength multiplexing network switching according to claim 2, wherein said working / standby switching means corresponding to the wavelength to be added / dropped has an electric / optical interface connected to the working / adding / dropping port. apparatus. 4. The apparatus according to claim 1, wherein each of the working / standby switching means includes means for simultaneously supplying the signal light to both the working system and the protection system to which the signal light is to be transmitted. Wavelength multiplexing network switching device. 5. An apparatus for detecting overhead of a signal frame from each wavelength output of said working system wavelength separation means and said protection system wavelength separation means, regenerating and repeating input light, and regenerating the regenerative relay light corresponding to said working / protection light. 5. The transmission terminal device according to claim 1, further comprising a transmission terminal device for supplying the switching terminal device.
Item 2. The wavelength multiplexing network switching device according to item 1. 6. A second transmission terminal device for regenerating and relaying output light of said working / standby switching means between said working / standby switching means and said working wavelength multiplexing means and said protection wavelength multiplexing means. 6. The method according to claim 1, wherein
Item 2. The wavelength multiplexing network switching device according to item 1. 7. The wavelength-division multiplexing network switching device according to claim 1, wherein said working system and said protection system both comprise ring optical transmission lines. 8. The working system and the standby system respectively
8. The wavelength multiplexing network switching device according to claim 7, comprising two transmission media having different transmission directions of the signal light. 9. A wavelength-division multiplexing network switching apparatus according to claim 1, wherein said wavelength-division multiplexing optical network system has a working system and a protection system and connects a plurality of nodes in a ring. A wavelength multiplexing optical ring network system comprising: