JP3526428B2 - Light path network - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical path network including an optical transmission device used in an optical communication system.

[0002]

2. Description of the Related Art FIGS. 1 to 3 are diagrams for explaining a failure recovery method assumed in a conventional optical path network. In the figure, 1 to 5 are optical cross-connect devices. The optical cross-connect devices are connected to each other by optical fibers.
As shown in FIG. 5, it is assumed that an optical path is set from the optical cross connect device 1 to the optical cross connect device 3 via the optical cross connect device 2 using the optical wavelength multiplexing transmission line 7. As shown in ITU-T Recommendation (draft) G.872, the optical wavelength multiplexing transmission line 7 includes a payload channel and a supervisory control channel. A data communication channel 8 used for transmitting information between the operation system 6 and each of the optical cross connect devices 1 to 5 is set in the supervisory control channel.

As shown in FIG. 2, when a failure occurs in the optical fiber between the optical cross-connect devices 2 and 3, failure information is transmitted to the operation system 6 and the operation system 6 is not used. Find resources and calculate detour routes. However, if the detour route is set in advance, it is not necessary to calculate each time a failure occurs. Here, the route from the optical cross-connect device 1 to the optical cross-connect device 3 via the optical cross-connect devices 4 and 5 is a detour route. When the detour route is determined, a command is sent to each associated optical cross-connect device, and as shown in FIG. 3, an optical path is set in the detour route and the communication line is restored. Such a restoration method is called restoration. In this restoration, since restoration is performed via the operation system 6, there is a problem that it takes a long time to restore.

4 to 6 are views for explaining another conventional method. As shown in FIG. 4, a working optical path from the optical cross-connect device 1 to the optical cross-connect device 3 via the optical cross-connect device 2 via the optical cross-connect device 2 using the optical WDM transmission line 7, It is assumed that backup optical paths are set in the optical cross-connect device 3 via the connecting devices 4 and 5, respectively. As shown in FIG. 5, when a failure occurs in the optical fiber between the optical cross connect devices 2 and 3, as shown in FIG. 6, the backup optical path is switched to the working optical path to maintain communication. can do. In this way, a recovery method that provides a backup path in advance is called protection, but this protection has a problem that the utilization efficiency of the equipment does not increase, and if the backup optical path is shared as a countermeasure, the network design becomes difficult. There is.

[0005]

In view of the above problems, it is an object of the present invention to provide an optical path network capable of high-speed restoration without being restricted by the network topology.

[0006] An optical path network comprising an optical transmission line and a plurality of optical cross-connect devices for connecting the optical transmission lines, wherein the optical path network comprises an optical path forming an optical channel and a control path. An ATM network is set, a VP or VC corresponding to an optical path is formed on the control ATM network in a one-to-one correspondence, and when a failure occurs in the optical path network, restoration is performed based on the configuration information of the control ATM network. It is characterized by performing.

In such an optical path network of the present invention,
The port number of the optical path may be associated with the port number of the ATM network, and the optical wavelength of the optical path may be associated with the VPI (virtual path identifier) or VPI and VCI (virtual channel identifier) of the ATM network. Also, when the ATM network has a spare VP or VC corresponding to the working VP or VC on a one-to-one basis and the optical path corresponding to the working VP or VC fails, the working VP or VC is supported. A means for transmitting the optical path switching request signal to the backup VP or VC may be provided. In this case, the ATM network may transfer the optical path switching request signal by the multicast path.

According to such an optical path network of the present invention, a backup path is configured in advance as a control ATM network, and when a failure actually occurs, restoration is performed based on the configuration information of the ATM network. I do. With such a configuration, it becomes possible to quickly perform the failure recovery of the optical path network.

[0009]

Embodiments of the present invention will be described below.
FIG. 7 is a diagram showing the configuration of an optical cross-connect device used in the optical path network of the present invention. In this figure, the optical supervisory control channel (OSC) is ITU-T recommendation (draft) G.872.
(Hereinafter, simply referred to as G.872) represents an optical supervisory control channel. Also, the main signal represents a payload channel in an optical transfer network conforming to G.872. In FIG. 7, 10 is a main part of the optical cross connect, 11 is a supervisory control part, 12
Is an optical supervisory control channel demultiplexer, 13 is an optical supervisory control channel transceiver, and 14 is an ATM switch.

The optical cross-connect main part 10 realizes main functions of the optical cross-connect device such as transmission / reception of a main signal system, route setting, and switching. The monitoring control unit 11 controls the entire optical cross-connect device, and further has functions of transmitting and receiving information to and from other optical cross-connect devices, transmitting and receiving information to and from the operating system, and executing commands from the operating system. . Optical supervisory control channel demultiplexer 12
Performs multiplexing and demultiplexing of the optical supervisory control channel and the main signal channel. The optical supervisory control channel transmission / reception unit 13 is connected to the transmission path, transmits / receives an optical supervisory control channel to / from another optical cross-connect device, transmits / receives a data communication channel DCC to / from the supervisory control unit 11, Functions such as various overhead processing in the optical supervisory control channel OSC, extraction of the VP or VC from the optical supervisory control channel OSC and transmission to the ATM switch 14, multiplexing of the VP or VC to the optical supervisory control channel OSC (OSC See Japanese Patent Application No. 11-172759, for example). The ATM switch 14 is a normal ATM switch.

FIG. 8 is a diagram for explaining the relationship between the control ATM network and the G.872 optical channel. Here, the control AT
The M network is an ATM network used for the supervisory control system. In FIG. 8, 21 and 22 are optical cross-connect devices, 23 is an ATM switch used for the control ATM network included in the optical cross-connect device 21, and 24 is a control ATM device included in the optical cross-connect device 22. It is an ATM switch used in the network. The ATM switches 23 and 24 have more ports than the optical cross-connect devices 21 and 22 including them. In FIG. 8, the optical cross-connect device 21 has ports 1 to 1
It is shown that it has four ports of port 4 and each port is connected to four ports of ports 1 to 4 of the optical cross connect device 22 by four optical channels of optical wavelengths λ1 to λ4. There is. For example, corresponding to the optical channel using the optical wavelength λ2 between the port 1 of the optical cross-connect device 21 and the port 1 of the optical cross-connect device 22, each port of the ATM switches 23 and 24 is also controlled on the control ATM network side. VC1 / 2 of VCI = 2 connecting 1 is set. Also, the most significant bit of an appropriate VPI is used as a working / spare bit to indicate whether the original optical path is working or spare, and the same contents as the port number are written in other bits. In this embodiment, when the most significant bit of the VPI is 1, it indicates the current use, and when it is 0, it indicates the reserve. The correspondence relationship between this optical path and the VC of the control ATM network can be arbitrarily determined as long as it uniquely corresponds.

FIG. 9 is a diagram for explaining the relationship between the optical path network that is actually operated and the control ATM network. 31-35 in the figure
Is an optical cross-connect device, λ1 to λ3 are optical wavelengths, and 11 is a supervisory control unit (see FIG. 7). In FIG. 9, the working optical path has an optical wavelength λ2 between the port 1 of the optical cross connect device 31 and the port 3 of the optical cross connect device 32, and the port 2 of the optical cross connect device 32 and the optical cross connect device 33. Of the optical cross-connect device 31 and the port 1 of the optical cross-connect device 34 with the optical wavelength λ2. Port 34 of device 34 and optical cross-connect device 35
, An optical wavelength λ1 is connected to the port 3 of the optical cross connect device 35, and an optical wavelength λ1 is connected to the port 2 of the optical cross connect device 35 and the port 1 of the optical cross connect device 33. ing. In this case, the backup optical path is not normally used and is operated only when a failure occurs in the working optical path.

In the control ATM network, a VC corresponding to the optical path network is set. For example, when connecting the port 1 of the optical cross-connect device 31 and the port 3 of the optical cross-connect device 32 with the optical wavelength λ2, the port 1 of the ATM switch of the optical cross-connect device 31 and the port of the optical cross-connect device 32 are connected. VCI = 2 between port 3 of ATM switch
VC is set. Based on this, the switching table of each optical cross-connect device and ATM switch is set. If the control ATM network is compatible with multicast, it is preferable to set it as a multicast path.

FIG. 10 shows a switching table of the ATM switch of each optical cross-connect device in the case of the configuration example shown in FIG. In each table of FIG. 10, the port of the monitor control unit 11 is assigned to port 0. In addition, the most significant bit of the VPI is divided and displayed as an active spare bit.
I represents a working spare bit and port number, and VCI represents an optical channel number. In the working spare bits, 1 represents working and 0 represents spare. If there are two outputs for input,
Copy the original cell and output two cells. This function is used if the ATM switch supports multicast. To output to port 0, write the input port number in the port number part of the original VPI field,
The CI number is written without changing the wavelength number. When input from port 0, the contents of the working spare bit / port number / optical channel number are saved as they are.

The above operation will be described with reference to FIG. AT
The M switch 14 has n + 1 input ports and output ports, of which 1 to n are connected to the ATM switch of the adjacent optical cross connect device. The remaining No. 0 is connected to the monitor control unit 11 in the optical cross connect device. As shown in FIG. 11 (b), the control ATM cell from the ingress port has a field of VPI and VCI in the overhead, a working spare bit for identifying working or spare, an output port number in the previous node, and a wavelength. The number is written. The cell input to the ATM switch is transferred to the next node (A route) or sent to the monitor control unit 11 via the 0th output port (B route). A
A cell passing through the route is assigned an output port number and an output wavelength number and transferred to the next node. A cell passing through the B route is assigned the ingress port number of the cell and is sent to the monitor control unit 11 without changing the wavelength number. Remaining C route,
That is, a cell heading from the monitor control unit 11 to the output port via the 0 input port is output by the monitor control unit 11 with the working spare bit, the output port number, and the wavelength number.
It is output from the desired output port without being rewritten by the M switch.

Next, the procedure of restoration when a failure occurs in the configuration of the embodiment of the present invention shown in FIG. 9 will be described. In the configuration shown in FIG. 9, it is assumed that a failure has occurred in the working optical path between the optical cross connect devices 32 and 33 as shown in FIG. In this case, the optical cross-connect device 33 detects a signal break and sends a switching request cell to the control ATM network toward the optical cross-connect device 35. Control A
The TM network transfers the switching request cell according to the set switching table. When the switching request cell is transferred via the multicast path, the switching request cell is detected by all of the path termination optical cross-connect device and the path relay optical cross-connect device. Upon receiving the switching request cell, the monitoring controller 11 can read the VPI and VCI fields of the switching request cell and specify the path to be switched. When detecting the switching request cell, the optical cross-connect device changes the connection state of the optical channel corresponding to the switching request for each link, and restores the optical path as shown in FIG.

[0017]

As described above, according to the present invention,
By providing a high-speed restoration means to the optical path network, which has been difficult in the past, and adopting restration, it is possible to effectively utilize network resources.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a failure recovery method assumed in a conventional optical path network.

FIG. 2 is a diagram for explaining a failure recovery method assumed in a conventional optical path network.

FIG. 3 is a diagram for explaining a failure recovery method assumed in a conventional optical path network.

FIG. 4 is a diagram for explaining another failure recovery method assumed in a conventional optical path network.

FIG. 5 is a diagram for explaining another failure recovery method assumed in a conventional optical path network.

FIG. 6 is a diagram for explaining another failure recovery method assumed in a conventional optical path network.

FIG. 7 is a diagram showing a configuration of an optical cross-connect device used in the optical path network of the present invention.

FIG. 8 is a diagram illustrating a relationship between a control ATM network and a G.872 optical channel.

FIG. 9 is a diagram illustrating a relationship between an optical path network that is actually operated and a control ATM network.

FIG. 10 is a diagram showing a switching table of an ATM switch of the optical cross connect device.

FIG. 11 is a diagram for explaining the operation of the ATM switch of the optical cross connect device.

FIG. 12 is a diagram illustrating a restoration procedure when a failure occurs in the configuration of the exemplary embodiment of the present invention.

FIG. 13 is a diagram illustrating a restoration procedure when a failure occurs in the configuration of the exemplary embodiment of the present invention.

[Explanation of symbols]

1-5 Optical cross-connect equipment 6 Operation system 7 Optical WDM transmission line 8 data communication channels 10 Optical cross-connect main part 11 Monitoring control unit 12 Optical supervisory control channel demultiplexer 13 Optical supervisory control channel transceiver 14 ATM switch 21, 22 Optical cross-connect equipment 23, 24 ATM switch 31-35 Optical Cross-Connect Device λ1 to λ3 Optical wavelength

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-9-36892 (JP, A) 2000 IEICE Communications Society Conference SB-8-3 IEICE Technical Report CS 2000-66 ( 58) Fields investigated (Int.Cl. ⁷ , DB name) H04L 12/56 H04B 10/02

Claims (4)

(57) [Claims] 1. An optical transmission line and a plurality of optical transmission lines connecting between the optical transmission lines.
An optical path network including an optical cross-connect device, wherein the optical path network includes an optical path forming an optical channel and a control path.
A control ATM network is set up, and an optical path is placed on the control ATM network.
A VP or VC corresponding to the optical path
When a failure occurs in the network, the control ATM network configuration information
An optical path network characterized by restoration based on this . 2. The optical path network according to claim 1, wherein:
The optical transmission line is an optical wavelength division multiplexing transmission line, the port number of the optical path and the port number of the control ATM network are made to correspond, and the optical wavelength of the optical path is made to correspond to the VPI or VCI of the control ATM network. An optical path network characterized by that. 3. A light path network as claimed in claim 1 or 2, wherein the control ATM network, VP or VC in the backup for one-to-one correspondence to the VP or VC of the active system is set, disability
The optical cross-connect device that detects the occurrence of harm is
An optical path network characterized by transmitting an optical path switching signal to an ATM network for use . 4. The optical path network according to claim 3, wherein the control ATM network transfers an optical path switching signal by a multicast path.