JPH11252049A - Unrequired alarm suppression method and device in wavelength multiplex communication network - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an unrequired alarm at an optical multiple section terminating poimt and an optical channel connection point and to easily identify a fault part. SOLUTION: When optical input interruption 51 is detected, an OTM index in an optical multiple section is subtracted by one and a node 4 is informed. Thus, the wavelength multiplex number (=2) of optical signals actually received by the node 4 and the OTM index defined in the optical multiple section become equal and OTM index mismatch 55 is canceled (57). Also, by the cancellation of the OTM index mismatch 55, the alarm is not reported to OpS (58). Thus, the unrequired alarm from the optical multiple section terminating point 44 and the optical channel connection point 35 is suppressed.

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 communication network for transmitting an optical signal using a wavelength division multiplexing technique and transmitting the signals while changing the route for each wavelength at a node on the way. In particular, the present invention relates to a wavelength division multiplexing communication network that does not have a function of generating and inserting a dummy light in each node.

[0002]

2. Description of the Related Art FIG. 2 is a flow chart showing that an unnecessary alarm is generated in a conventional wavelength division multiplexing communication network. FIG. 3 is a diagram showing a setting state of an optical channel. In each node, optical channels are connected while changing the route for each wavelength. For example, as shown in FIG. 3, the optical channels 25 and 26 are set from the node 1 to the node 4 via the transmission path 11, the node 3, and the transmission path 13, and the nodes 2 to 4
The optical channel 27 is set via the transmission path 12, the node 3, and the transmission path 13. Optical multiple sections 21 to 23 are defined corresponding to the transmission paths 11 to 13,
The M levels are defined as 2, 1, and 3, respectively.

[0003] FIG. 2 is a flow chart showing a case where a failure occurs in the transmission line 12 (optical multiple section 22) in the optical channel setting state shown in FIG.
Shows the behavior in. That is, the optical channel 27
The case where is missing will be described.

In a wavelength division multiplexing communication network, the presence or absence of an optical signal is monitored also at the optical channel connection points 33 to 35 in order to facilitate identification of a failure point. The transmission paths 11 to 13 accommodate single or plural optical channels having different wavelengths. Assuming that the maximum number of multiplexed wavelengths on a transmission line is M, an optical signal of 0 to M waves is multiplexed on each transmission line as occasion demands.

A network node of a wavelength division multiplexing communication network
The interface signal format is shown in FIG. 4 (Okamoto: "NNI configuration of WDM optical path transmission network",
IEICE Society Conference, B-10-9
8, September 1997). The wavelength division multiplexed signal has an optical section overhead channel (λSV) and M wavelengths (λ1 to λM).
Of optical section payload channels of M + 1. The signal of this M + 1 wavelength is OTM-
It is defined as M (optical transport module level M). Each node transmits information in units of the OTM signal.

Each transmission line needs to handle signals from OTM-1 to OTM-M as occasion demands. Therefore, the OTM level is defined as one of the optical multiple section overhead information as an OTM index, and this information is notified to an adjacent node by an optical section overhead channel. The OTM level of each optical multiple section is managed using this OTM index.

When a failure occurs in the transmission line 12, the node 3
In, the optical input disconnection 54 is detected at the optical multiple section termination point 42 and the optical input disconnection 51 is detected at the optical channel connection point 34. At the node 4, an OTM index mismatch 55 is detected at the optical multiple section termination point 44, an optical input disconnection 52 is detected at the optical channel connection point 35, and an optical input disconnection 53 is detected at the optical channel termination point 32.

This OTM index mismatch 55
Indicates that the optical OTM level defined in the overhead information of the optical multiple section 23 is 3, whereas the optical channel 2 is actually
7 is missing, which is a mismatch with the OTM index caused by receiving only two wavelength multiplexed signals. As described above, the operation system (OpS) from the optical multiple section terminal point 42 and the optical channel connection point 34 in the node 3 and the optical multiple section terminal point 44, the optical channel connection point 35 and the optical channel terminal point 32 in the node 4 ) Will raise an alarm.

[0009] Here, the location of a failure in the optical channel is identified by the following procedure. That is, first, since an alarm is issued from the optical channel termination point 32, it is determined that a failure has occurred in the corresponding optical channel 27. Next, the optical channel connection point of the optical channel 27 is changed to the optical channel termination point 32.
And detects the first optical channel connection point (in the example of FIG. 2, the optical channel connection point 34) that raised the alarm. As a result, it is possible to identify that a failure has occurred in the transmission line 12 that transmits a signal to the optical channel connection point 34.

[0010] Similarly, the identification of a fault location in the optical multiple section is performed in the following procedure. That is, the optical multiple section termination point that first raised the alarm is
Since it is the optical multiple section termination point 42, it can be identified that a failure has occurred in the corresponding optical multiple section 22 (OTM-1).

As described above, the alarms necessary for identifying the fault location include the alarms from the optical multiple section termination point 42 and the optical channel connection point 34 at the node 3 and the optical channel at the node 4 among the above five alarms. End point 3
There are a total of three alarms from two. That is, the remaining two alarms (the optical multiple section termination point 4 at the node 4)
4. The alarm from the optical channel connection point 35 is unnecessary.

On the other hand, if the node 3 has a function of generating / inserting a dummy light, it is possible to compensate for an optical signal that has been lost due to a failure or the like, and to use the optical channel / overhead channel shown in FIG. AIS (Alarm
By transmitting an Indication Signal) signal, a fault condition can be transmitted downstream. As a result, the detection of the failure at the optical multiple section termination point 44 and the optical channel connection point 35 at the node 4 is canceled, and unnecessary alarms can be suppressed. However, it is difficult to implement this dummy light generation / insertion function in each node, especially in an all-optical network, in terms of hardware implementation.

[0013]

As described above, since it is difficult to provide a dummy light generation / insertion function in each node as described in the conventional example, if it is not provided, an unnecessary alarm is notified to the OpS. Will be done. In a large-scale WDM communication network, since each optical channel is set via many nodes, a large number of unnecessary alarms are raised to the OpS and processed. In addition, unnecessary processing is applied to the OpS due to unnecessary alarm processing.

The present invention relates to a wavelength division multiplexing communication network having no function of generating / inserting dummy light, detecting the presence or absence of an optical signal at an optical channel connection point, managing an OTM level in an optical multiple section, and terminating the optical multiple section. It is an object of the present invention to provide a wavelength division multiplexing communication network that suppresses unnecessary alarms at points and optical channel connection points, and facilitates identification of a failure point.

[0015]

According to the present invention, an optical channel is connected between a plurality of optical channel termination points via a plurality of optical channel connection points, and a plurality of optical channels are connected to a transmission line between nodes by a wavelength multiplexing technique. In a wavelength division multiplexing communication network in which an optical channel is connected by a node having an optical channel connection point and transmitted by wavelength multiplexing, the presence or absence of an optical signal is detected at an optical channel connection point, and an optical multiple section corresponding to a transmission path is detected. The OTM level, which is an index of the number of wavelength multiplexing at that time, is managed, and dummy light generation /
In a type of wavelength multiplexing communication network having no insertion function,
When the optical input disconnection is detected at the optical channel connection point, the OTM of the next-stage optical multiple section corresponding to the optical channel is detected.
By changing the OTM index indicating the level and transmitting it to the adjacent node, the optical multiple section is reconfigured. Further, when the optical input disconnection is detected at the optical channel connection point, a failure is detected at the optical multiple section termination point Only when the alarm is issued from the optical channel connection point to the wavelength division multiplexing network operation system, that is,
Even when the optical input disconnection is detected at the optical channel connection point, if the corresponding optical multiple section is normal, no alarm is issued from the optical channel connection point, thereby suppressing unnecessary alarms.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS §1. Overview The unnecessary alarm suppression method in the wavelength division multiplex communication network of the present invention,
In a node having an optical multiple section termination point and an optical channel connection point, unnecessary alarms to the wavelength division multiplexing network operation system (OpS) are suppressed by the following operation. When the optical input disconnection is detected at the optical channel connection point, the optical multiple section of the next stage corresponding to the optical channel is reconfigured, and the O in the optical multiple section is reconfigured.
The TM index mismatch is released and the state is returned to the normal state. The reconfiguration of the optical multiple section is realized by changing the OTM index, which is an index of the number of multiplexed wavelengths (OTM level) in the optical multiple section, to a correct value, that is, reducing the OTM index. As a result, unnecessary alarms due to OTM index mismatch in the optical multiple section at the optical multiple section termination point due to an upstream failure are suppressed.

Further, when an optical input disconnection is detected at the optical channel connection point, an alarm is issued from the optical channel connection point to the wavelength multiplexing communication network operation system only when a failure is detected at the optical multiple section termination point. I do. That is, even if the optical input disconnection is detected at the optical channel connection point, if the corresponding optical multiple section is normal, no alarm is issued from the optical channel connection point to the OpS. This allows
Unwanted alarms at the optical channel connection point are suppressed. As described above, unnecessary alarms at the optical multiple section termination point and the optical channel connection point due to a failure in the wavelength division multiplexing communication network can be suppressed, and the failure location can be easily identified.

Thus, in the wavelength division multiplexing communication network,
Even if an optical signal is lost due to a failure in a transmission line or the like, the optical multiple section is reconfigured, and an alarm at the optical channel connection point is raised to OpS only when the optical multiple section also detects a failure. By doing so, in a wavelength division multiplexing communication network having no dummy light generation / insertion function,
Unnecessary switching can be suppressed.

§2. FIG. 1 is a flowchart showing how to suppress unnecessary alarms in a wavelength division multiplexing communication network according to an embodiment of the present invention. FIG. 3 is a diagram showing a setting state of an optical channel. As shown in FIG. 3, optical channels 25 and 26 are set from the node 1 to the node 4 via the transmission path 11, the node 3, and the transmission path 13.
An optical channel 27 is set from the node 2 to the node 4 via the transmission path 12, the node 3, and the transmission path 13. The optical multiple sections 21 to 21 corresponding to the transmission lines 11 to 13
23 are defined and the OTM levels are 2, 1, 3 respectively
Is defined as

The flow chart shown in FIG. 1 shows nodes 2 to 4 when a failure occurs in the transmission line 12 (optical multiple section 22) in the optical channel setting state shown in FIG.
Shows the behavior in. That is, the optical channel 27
The case where is missing will be described. The occurrence of a failure and the detection of the failure are the same as in the conventional example of this specification.

When a failure occurs in the transmission path 12, the node 3
In, the optical input disconnection 54 is detected at the optical multiple section termination point 42 and the optical input disconnection 51 is detected at the optical channel connection point 34. At the node 4, the OTM index mismatch 55 at the optical multiple section termination point 44
The optical input disconnection 52 is detected at the optical channel connection point 35, and the optical input disconnection 53 is detected at the optical channel termination point 32.

Since the optical input disconnection 51 is detected at the optical channel connection point 34, the OTM in the optical multiple section 23 is
The index is decremented by 1, the optical multiple section is reconfigured, and notified to the node 4 by the optical section overhead channel. That is, the OTM level of the optical multiple section 23 is defined as 2.

As a result, the value (= 2) of the wavelength multiplexing number of the optical signal actually received by the node 4 becomes equal to the (reconstructed) OTM index defined in the optical multiple section 23, and the OTM index mismatch 55 is released (57). Further, the optical input disconnection 52 is detected at the optical channel connection point 35 in the node 4,
By the reconfiguration of the optical multiple section 23, the OTM index mismatch 55 at the optical multiple section termination point 44 is released and the optical multiple section 23 returns to the normal state.
No alert to pS is notified (58).

As described above, the alarm from the optical multiple section termination point 44 and the optical channel connection point 35 is suppressed, and the optical input disconnection 54 at the optical multiple section termination point 42 and the optical Connection point 3
Only alarms relating to the optical input disconnection 51 at 4 and the optical input disconnection 52 at the optical channel termination point 32 are notified to the OpS.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to the embodiments, and changes in design and the like may be made without departing from the gist of the present invention. Even if there is, it is included in the present invention. In the present embodiment, a case has been described where a failure occurs in a transmission line (optical multiple section) in which one optical channel is set. When a failure occurs in a transmission line in which a plurality of optical channels are set, an optical input disconnection is detected at a plurality of optical channel connection points at an output node of the failure transmission line.
For example, when the optical input disconnection is detected at n optical channel connection points among the optical channels accommodated in the same next-stage optical multiple section, the OTM index of this optical multiple section is set to n before the occurrence of the failure. By setting the value to the subtracted value, the optical multiple section is reconfigured, and unnecessary alarms are suppressed as described above.

[0026]

As described above, the unnecessary alarm suppression method of the present invention can suppress unnecessary alarms in a wavelength division multiplexing communication network that does not have a function of generating / inserting a dummy light in a node in the middle. As a result, only the minimum alarm necessary for identifying the fault location is issued, and the fault location can be easily identified.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an example of an unnecessary alarm suppression method in a wavelength division multiplexing communication network according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an example of an alarm generation method in a wavelength division multiplexing communication network according to a conventional example.

FIG. 3 is an explanatory diagram showing an example of an optical channel connection in the wavelength multiplexing communication network according to the embodiment and the conventional example.

FIG. 4 is an explanatory diagram showing an example of a format of a network node interface signal.

[Description of Signs] 1-4: Nodes 11, 12, 13: Transmission Lines 21, 22, 23: Optical Multiple Sections 25, 26, 27: Optical Channels 31, 32: Optical Channel Termination Points 33, 34, 35: Optical Channel connection points 41, 42, 43, 44: Optical multiple section termination points 51, 52, 53, 54: Optical input interruption 55: OTM index mismatch 56: Optical multiple section reconstruction 57: OTM index mismatch cancellation 58: Optical channel connection Alarm suppression from point

Claims (2)

[Claims] An optical channel is connected between a plurality of optical channel termination points via a plurality of optical channel connection points. A plurality of optical channels are wavelength-multiplexed and transmitted to a transmission line between nodes by a wavelength multiplexing technique. In a wavelength division multiplexing communication network in which optical channels are connected by nodes having channel connection points, the presence or absence of optical signals is detected at the optical channel connection points, and the number of wavelength multiplexing at that time is detected in the optical multiple section corresponding to the transmission path. In a wavelength division multiplexing communication network that manages an OTM level as an index and does not have a function of generating / inserting dummy light in a node on the way, if an optical input disconnection is detected at an optical channel connection point, the next channel corresponding to that optical channel is detected. OTM with multiple optical sections
The optical multiple section is reconfigured by changing the OTM index indicating the level and transmitting it to the adjacent node. Further, when the optical input disconnection is detected at the optical channel connection point, a failure is detected at the optical multiple section termination point. Only when the optical channel connection point issues an alarm to the wavelength division multiplexing network operation system, that is, even if the optical input section detects an optical input disconnection, the corresponding optical multiple section is normal. For example, an alarm is not issued from the optical channel connection point, thereby suppressing unnecessary alarms. 2. An optical channel is connected between optical channel termination points via a plurality of optical channel connection points, and a plurality of optical channels are wavelength-multiplexed and transmitted to a transmission line between nodes by a wavelength multiplexing technique. In a wavelength division multiplexing communication network in which optical channels are connected by nodes having channel connection points, the presence or absence of optical signals is detected at the optical channel connection points, and the number of wavelength multiplexing at that time is detected in the optical multiple section corresponding to the transmission path. In a wavelength division multiplexing communication network that manages an OTM level as an index and does not have a function of generating / inserting dummy light in a node on the way, if an optical input disconnection is detected at an optical channel connection point, the next channel corresponding to that optical channel is detected. OTM with multiple optical sections
OTM index changing means for reconfiguring an optical multiple section by changing an OTM index indicating a level and transmitting the OTM index to an adjacent node; and when an optical input disconnection is detected at an optical channel connection point, an optical multiple section termination point is used. Only when a failure is detected, an alarm is issued from the optical channel connection point to the wavelength division multiplexing network operation system, that is, even if the optical input disconnection is detected at the optical channel connection point, the corresponding optical multiple section is An unnecessary alarm suppressing device in a wavelength division multiplexing communication network, comprising: an alarm issuing unit that does not issue an alarm from the optical channel connection point when it is normal.