JP2001168877A - Light path network - Google Patents

Abstract

(57) [Problem] To provide an optical path network which can be restored at high speed without being restricted by a network topology. SOLUTION: There is provided an optical path constituted by a plurality of optical cross-connect devices, and an ATM network in which the optical path and the VP or VC of the ATM correspond one-to-one. In such an optical path network, the port number of the optical path is made to correspond to the port number of the ATM network, and the optical wavelength of the optical path is set to the VP of the ATM network.
It may correspond to I or VPI and VCI. Also, A
When the TM network has a spare VP or VC corresponding to the working VP or VC on a one-to-one basis, and a failure occurs in the optical path corresponding to the working VP or VC, the spare corresponding to the working VP or VC is generated. Means for transmitting an optical path switching request signal to the VP or VC. In this case, the ATM network
The optical path switching request signal may be transferred by a multicast path.

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 for 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, reference numerals 1 to 5 denote optical cross-connect devices. The optical cross-connect devices are connected to each other by optical fibers.
As shown in (1), 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 multiplex transmission line 7. As shown in ITU-T Recommendation (draft) G.872, the optical wavelength division multiplexing transmission line 7 is provided with 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 monitoring control channel.

As shown in FIG. 2, when a failure occurs in an optical fiber between the optical cross-connect devices 2 and 3, failure information is transmitted to an operation system 6, and the operation system 6 is used for an unused network. Search for resources and calculate a detour route. However, when the detour route is set in advance, it is not necessary to calculate each time a failure occurs. Here, a 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 of the related optical cross-connect devices, and as shown in FIG. 3, an optical path is set on the detour route and the communication line is restored. Such a restoration method is referred to as restoration. However, since restoration is performed through the operation system 6, there is a problem that it takes a long time to restore.

FIGS. 4 to 6 are views for explaining another conventional method. As shown in FIG. 4, a working optical path is transmitted 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-division multiplex transmission line 7, It is assumed that a spare optical path is set in the optical cross-connect device 3 via the connection 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, the communication is maintained by switching the backup optical path to the working optical path as shown in FIG. can do. As described above, the recovery method in which a backup path is provided in advance is called protection, but this protection has a problem that the utilization efficiency of the equipment does not increase, and as a countermeasure, the network design becomes difficult if the backup optical path is shared. There is.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical path network which can be restored at high speed without being restricted by the network topology.

[0006]

In order to achieve the above object, an optical path network according to the present invention comprises: an optical path comprising a plurality of optical cross-connect devices; and an optical path and an ATM VP.
(Virtual path) or VC (virtual channel) in one-to-one correspondence with an ATM network.

In such an optical path network of the present invention,
The port number of the optical path may correspond to the port number in the ATM network, and the optical wavelength of the optical path may correspond to VPI (virtual path identifier) or VPI and VCI (virtual channel identifier) of the ATM network. In addition, the ATM network has a spare VP or VC corresponding to the working VP or VC on a one-to-one basis, and if the optical path corresponding to the working VP or VC fails, the ATM network responds to the working VP or VC. Means for transmitting an optical path switching request signal to a backup VP or VC to be used. In this case, the ATM network may transfer the optical path switching request signal through the multicast path.

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

[0009]

Next, embodiments of the present invention will be described.
FIG. 7 is a diagram showing a 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 based on the ITU-T Recommendation (draft) G.872
(Hereinafter simply referred to as G.872). The main signal represents a payload channel in an optical transmission network conforming to G.872. In FIG. 7, 10 is a main part of the optical cross-connect, 11 is a monitoring control unit,
Denotes an optical supervisory control channel demultiplexing unit, 13 denotes an optical supervisory control channel transmitting / receiving unit, and 14 denotes an ATM switch.

The optical cross-connect main unit 10 realizes main functions of the optical cross-connect device, such as transmission and reception of a main signal system, route setting, and switching. The monitoring control unit 11 is responsible for controlling the entire optical cross-connect device, and further has a function of transmitting and receiving information to and from other optical cross-connect devices, transmitting and receiving information to and from an operation system, and executing commands from the operation 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 transmitting / receiving unit 13 is connected to a transmission line, and 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, It has functions such as various overhead processing in the optical supervisory control channel OSC, extraction of VP or VC from the optical supervisory control channel OSC, transmission to the ATM switch 14, and multiplexing of VP or VC to the optical supervisory control channel OSC (OSC (See, for example, Japanese Patent Application No. 11-172759). The ATM switch 14 is a normal ATM switch.

FIG. 8 is a diagram for explaining the relationship between a control ATM network and G.872 optical channels. Here, the control AT
The M network is an ATM network used for a supervisory control system. In FIG. 8, reference numerals 21 and 22 denote optical cross-connect devices, reference numeral 23 denotes an ATM switch used for a control ATM network included in the optical cross-connect device 21, and reference numeral 24 denotes a control ATM included in the optical cross-connect device 22. An ATM switch used for a network. The ATM switches 23 and 24 have more ports than the optical cross-connect devices 21 and 22 including them. FIG. 8 shows that the optical cross-connect device 21
The figure shows a case where four ports of port 4 are provided, and each port is connected to four ports of port 1 to port 4 of the optical cross-connect device 22 by four optical channels of optical wavelengths λ1 to λ4. I have. 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, the respective ports of the ATM switches 23 and 24 are also used on the control ATM network side. VC1 / 2 of VCI = 2 connecting 1 is set. Also, the most significant bit of the appropriate VPI is used as a working / spare bit for indicating 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 above-mentioned VPI is 1, the working is indicated, and when it is 0, the spare is indicated. The correspondence between the 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 actually operated optical path network and the control ATM network. In the figure, 31-35
Is an optical cross-connect device, .lambda.1 to .lambda.3 are optical wavelengths, and 11 is a supervisory control unit (see FIG. 7). FIG. 9 shows that 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. Is connected to the port 2 of the optical cross-connect device 31 and the port 1 of the optical cross-connect device 34 at the optical wavelength λ2. Port 3 of device 34 and optical cross-connect device 35
The optical wavelength .lambda.1 is connected to the port 3 of the optical cross-connect device 35 and the optical wavelength .lambda.1 is connected to the port 1 of the optical cross-connect device 33 at the optical wavelength .lambda.1. 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 the port 1 of the optical cross-connect device 31 and the port 3 of the optical cross-connect device 32 are connected by 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
Is set. Based on this, the switching table of each optical cross-connect device and the ATM switch is set. The control ATM network is preferably set as a multicast path if it is compatible with multicast.

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 monitoring control unit 11 is assigned to port 0. In addition, the most significant bit of the VPI is separately displayed as a working spare bit.
I represents a working spare bit and a port number, and VCI represents an optical channel number. As for the working spare bits, 1 represents working and 0 represents spare. If there are two outputs for the 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 portion of the original VPI field,
The CI part 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 stored as they are.

The above operation will be described with reference to FIG. AT
The M switch 14 has (n + 1) input and output ports, of which 1 to n are connected to the ATM switch of the adjacent optical cross-connect device. The remaining number 0 is connected to the monitoring control unit 11 in the optical cross-connect device. As shown in FIG. 11 (b), the control ATM cell from the incoming port includes, in the VPI and VCI fields in the overhead, a working spare bit for identifying working or protection, an outgoing port number at the previous node, and a wavelength. The number has been written. The cell input to the ATM switch is transferred to the next node (A route) or sent to the monitoring control unit 11 via the 0th outgoing port (B route). A
A cell passing through the route is given an output port number and an output wavelength number, and is transferred to the next node. A cell passing the B route is given an input port number of the cell, and is sent to the monitoring control unit 11 with the wavelength number unchanged. The remaining C route,
That is, the cell going from the monitoring control unit 11 to the output port via the input port 0 is output by the monitoring control unit 11 with the working spare bit, the output port number, and the wavelength number.
The data is output from a desired output port without being rewritten by the M switch.

Next, a 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 interruption and sends a switching request cell to the optical cross-connect device 35 to the control ATM network. A for control
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 in all of the path terminating optical cross-connect device and the path relay optical cross-connect device. Upon receiving the switching request cell, the monitoring control unit 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 high-speed restoration means, which has been difficult in the past, to an optical path network and employing restoration, network resources can be effectively used.

[Brief description of the 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 for explaining the relationship between a control ATM network and G.872 optical channels.

FIG. 9 is a diagram illustrating a relationship between an optical path network 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 illustrating 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 embodiment of the present invention.

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

[Explanation of symbols]

 1-5 Optical cross-connect device 6 Operation system 7 Optical wavelength multiplex transmission line 8 Data communication channel 10 Optical cross-connect main part 11 Supervisory controller 12 Optical supervisory control channel demultiplexer 13 Optical supervisory control channel transmitter / receiver 14 ATM switch 21 22 Optical cross connect device 23, 24 ATM switch 31-35 Optical cross connect device λ1-λ3 Optical wavelength

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Satoshi Okamoto 2-3-1 Otemachi, Chiyoda-ku, Tokyo F-term in Nippon Telegraph and Telephone Corporation (reference) 5K002 DA02 DA09 EA05 EA31 5K030 GA12 HA10 JL03 KX20 LA08 LA17 MB01 MD02 9A001 CC07 KK16 LL05

Claims (4)

[Claims] 1. An optical path network comprising: an optical path composed of a plurality of optical cross-connect devices; and an ATM network in which the optical path and an ATM VP or VC correspond one-to-one. 2. The optical path network according to claim 1, wherein a port number of the optical path is associated with a port number of the ATM network, and an optical wavelength of the optical path corresponds to VPI or VPI and VCI of the ATM network. An optical path network, characterized in that: 3. The optical path network according to claim 1, wherein the ATM network includes a spare VP or VC corresponding to a working VP or VC one-to-one, and corresponds to the working VP or VC. An optical path network comprising: means for transmitting an optical path switching request signal to a backup VP or VC corresponding to the working VP or VC when a failure occurs in the optical path to be performed. 4. The optical path network according to claim 3, wherein said ATM network transfers said optical path switching request signal through a multicast path.