JP2001144780A - Path setting method, path change-over method and node device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To previously and mutually identify a faulty part when change-over into a standby path is executed in respective nodes on an active path. SOLUTION: When the active path and its standby path are previously set in a network, usable wave lengths are classified into a plurality of groups, each group is assigned to be the one for setting the active path in mutually different transmission media and also the assignment of the groups are decided to permit each group to be the one for setting the standby path in the transmission medium being different from the medium where the groups are assigned for setting the active path and also to prevent the mutual superimposition of the transmission media in the respective groups.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a path setting method, a path switching method, and a node device, and can be applied to, for example, an optical wavelength division multiplexing network system.

[0002]

2. Description of the Related Art In the field of optical wavelength division multiplexing network systems, many studies have been made on a method of setting an optical path. Hereinafter, a conventional assignment method of the working path and the protection path will be described with reference to FIG. In addition,
In the following description, the path connecting nodes N1 and N2 in FIG. 2 is referred to as “path 12”, and the path connecting nodes N1 and N3 is referred to as “path 1”.
3 ".

[0003] Here, the active path 1 in the "path 12"
2 is set to pass through the nodes N1-N2. The current path 13 in the “path 13”
Is set to pass through the nodes N1-N2-N3.

[0004] On the other hand, it is assumed that the protection path set for recovery from the failure of the working path is set as follows. For example, as a backup path of the “path 12” when a failure occurs in the link L12, the nodes N1-N
5-N2 is set, and a backup path of "path 13" is set to pass through nodes N1-N4-N2-N3. Hereinafter, this backup path is referred to as a backup path 13-1. In addition, it is assumed that a backup path of “path 13” when a failure occurs in the link L23 is set to pass through the nodes N1-N2-N5-N3. Hereinafter, this backup path is referred to as the backup path 13-2.
That.

[0005]

However, in the optical path setting method for setting the working path and the protection path by the conventional method, when a fault occurs, the location of the fault is identified, the wavelength assigned to the protection path is determined, and the protection path is determined. Had to be switched to FIG. 3 shows an example of a hardware configuration for identifying a fault location.

In FIG. 3, a fault detecting means 1 judges a signal transmitted through a network (a signal which is separated by a wavelength separating means A1 for each wavelength and then split by each of optical splitting means C1 to C4). It is a means to do. The failure detecting means 2 is a signal to be transmitted to the network (a signal to be transferred to another node by the optical signal switching means SW and sent to the wavelength multiplexing means A2, which is branched by each of the optical branching means C1 to C4. Signal).
The failure detecting means 3 is a signal received by the own node as a destination (a signal to be transferred to the own node by the optical signal switching means SW and sent to the photoelectric conversion means O / E, This is a means for determining each of the signals C1 to C4).

For example, in FIG. 2, when the failure detecting means 2 of the node N1 is normal and an abnormality is found by the failure detecting means 1 of the node N2, it can be determined that the link 12 has a failure. Further, for example, if the failure detection unit 3 of the node N1 is normal, but the failure detection unit 3 detects an abnormality, it can be determined that the optical signal exchange unit SW has a failure.

As described above, when an attempt is made to identify a fault location by monitoring an optical signal, many fault detection means (at least three) are required, and there is a problem in that the hardware cost of the node increases.

In addition, for example, "path 13" in FIG.
When a failure occurs in the (N1-N2-N3) link 12, all the failure detection means of the nodes N2 and N3 determine that the failure is abnormal. Therefore, the node N3 determines whether the link 12 is abnormal or the link 13 is abnormal. Cannot be determined only from the determination result of the failure detection means of the node N3, and it is necessary to exchange information between the nodes to identify the failure location. Therefore, there is a problem that processing becomes complicated and it takes time to switch the failed path to the backup path.

[0010]

(A) In order to solve this problem, in the first invention according to the first aspect, when a working path and its backup path are set in advance on a network, the path is used. The possible wavelengths are classified into a plurality of groups, each group is allocated for setting a working path in a different transmission medium, and each group is allocated to a protection medium in a transmission medium different from the transmission medium allocated for setting a working path. Assignments are determined for path setting and in such a manner that transmission media do not overlap each other in each group. With this assignment, it is not necessary to switch the wavelength when switching is performed.

(B) According to a second aspect of the present invention, in the first aspect, the same wavelength is assigned to the working path and its protection path. With this assignment, it is not necessary to switch the wavelength when switching is performed.

(C) In a third aspect of the present invention, in the first or second aspect, the working path is set bidirectionally between the nodes.

(D) According to a fourth aspect of the present invention, a working path and its protection path are set in advance on a network, and each of the working paths and the protection paths is set to the other path to be used. When a route is set so as not to be included, the failure detection of the working path shall be performed only at the destination node of each path, and when the occurrence of a failure is detected, the destination node switches from the working path to the protection path. To switch the route to By using such a path switching method, the failure detection operation on the relay node becomes unnecessary, and the path can be quickly switched accordingly.

(E) According to a fifth aspect of the present invention, in the fourth aspect, the failure detection of the working path is performed on the lead-in line to the destination node itself. By doing so, no matter where a failure occurs on the path of the working path, it can be detected as a failure without exception.

(F) In the sixth aspect of the present invention, in each of the fourth and fifth aspects, each of the nodes located on the path of the protection path passes the protection path through itself. The route is set beforehand. With this setting, switching from the working path to the protection path can be realized only by switching between the source node and the destination node.

(G) According to a seventh aspect of the present invention, when the working path and its protection path are set in advance on the network, the working path to be set and its protection path include: As a node device in a network in which a route is set so that each route does not include the route used by the other, a failure occurs in any location on the working path from the signal state on the service line to the own node. A device provided with only a failure detection means for detecting whether or not a failure has occurred is used. With this configuration, it is possible to achieve both the function of switching to the backup path based on the detection of a failure in the working path and the miniaturization of the hardware configuration.

(H) According to the eighth aspect of the present invention, when the node device according to the seventh aspect of the present invention is located on the path of the protection path, the protection path passes through the protection device. To set the route as follows.
By using the node device having such a setting, switching from the working path to the protection path can be realized only by switching between the source node and the destination node.

(I) In a ninth aspect of the present invention, as the node device in the seventh or eighth aspect, the same wavelength is assigned to the working path and its protection path. By making such an assignment,
Switching can be performed without wavelength switching.

(J) In the tenth aspect of the present invention, when a working path and its backup path are set in advance on a network as a node device, a plurality of usable frequency bands are set. Classify into groups,
Each group is allocated for setting a working path in a transmission medium different from each other, and each group is also used for setting a protection path in a transmission medium different from the transmission medium allocated for setting a working path, and each group is used for setting a protection path. A device provided with a path assignment determining means for determining assignment so that transmission media do not overlap is used. With this configuration, it is not necessary to switch the frequency band when performing the switching.

(K) In the eleventh aspect of the present invention, the same frequency band is allocated to the working path and its protection path as the node device in the tenth aspect. By making such an assignment,
When performing the switching, it is not necessary to switch the frequency band.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (A) First Embodiment First, in a first embodiment, a path setting method that simplifies the hardware configuration of a node, and a failure when such a setting method is adopted. The determination method and the hardware configuration of the node will be described.

A feature of the path setting method according to the present embodiment is that, when the working path and its backup path are set, there is no overlap between the paths in advance. With such a setting, even if it is not known where a failure has occurred in the working path, it is possible to avoid the failure location in many cases by simply switching the path to the backup path,
Early recovery can be realized.

FIG. 1 shows an example of a hardware configuration of a node provided in a network system adopting the setting method. In FIG. 1, A1 is a wavelength separating means,
A2 denotes a wavelength multiplexing unit, SW denotes an optical signal switching unit, and E /
O is an electro-optical converter, O / E is an opto-electric converter, C
1 to Cn represent optical branching means, and D1 represents fault detecting means.

As shown in FIG. 1, an optical wavelength multiplexed signal input from a transmission line of a network is separated into signals for each wavelength by a wavelength separating means A1, and the separated signals are input to an optical signal switching means SW. . The optical signals input to the optical signal switching means SW are output to the wavelength multiplexing means A2 or the photoelectric conversion means O / E by switching the optical signal switching means SW. The optical signal exchange means SW is also connected to the electro-optical conversion means E / O. Further, the signal output from the optical signal exchange means SW to the photoelectric conversion means O / E is branched by the optical branching means C1 to Cn, one of which is output to the photoelectric conversion means O / E and the other is output to the failure detection means D1. It is configured to be.

As described above, the number of the fault detection means D1 installed in the node in the present embodiment is one, and the installation place is also between the optical signal exchange means SW and the photoelectric conversion means O / E, that is, Only the position where the signal addressed to the own node can be monitored. This means that even if a certain path passes through a plurality of nodes, only one failure point needs to be detected. Due to this configuration, the hardware configuration is naturally small, and switching to the backup path is possible without specifying a failure point with another node, so that a quick recovery is possible. .

Hereinafter, the path setting method and the switching method according to the present embodiment will be described with reference to the network configuration shown in FIG. 2 as an example.
In FIG. 2, N1 to N5 denote nodes, L12,
L14, L15, L23, L24, L25, and L53 represent links.

First, the working path and the protection path are set so as to pass through different paths. For example, "Pass 1
Assuming that the working route of "2" is N1-N2, its backup route is set to N1-N4-N2. As is clear from FIG. 2, there is no overlapping part of the route (link) in each case.
Further, when the working route of “path 13” is N1-N2-N3, the backup route is set to N1-N5-N3.
Also in this case, there is no overlapping part of the route (link).

Now, it is assumed that a failure has occurred in the link L12. This failure is caused by the destination (destinatio
n) The failure is detected by the failure detection means D1 provided in the node N2, which is a node, and it is determined that a failure has occurred at any point on the "path 12." As a result, the failure detecting unit D1 sets the “path 12” to the backup path (N1-N4-N).
It determines that the switching should be performed to 2), instructs the switching, and notifies the other nodes of the switching using a known technique (a control channel, a dedicated control line, or the like).
Similarly, in the “path 13”, the failure in the link L12 is detected by the failure detecting means D1 provided in the node N3 which is the destination node, and is switched to the preset backup path (N1-N5-N3). Can be Needless to say, the execution of the switching is notified to the other nodes using a known technique. In both cases,
Since the backup path does not include the failed active link n-link, normal communication is resumed after the switching.

On the other hand, when a failure occurs in the link L23 of the working path, only the "path 13" includes the link L23, so that only the destination node N3 of the "path 13" causes the failure. Detecting and switching to a preset backup path (N1-N5-N3) is executed.

As described above, in the present embodiment, the setting method for preventing the overlapping of the working path and the protection path from occurring is adopted as the path setting method.
It is only necessary to detect the occurrence of a failure (not a failure location) in each path by the failure detection means D1 provided in the destination node (since the same failure location is not switched even when switching to the backup path), the failure location is determined. It is possible to move to the backup path without identification. Therefore, switching to the backup path can be performed in a short time. Moreover, the failure detection means D1
The hardware configuration can be simplified because it is only necessary to set the position before the photoelectric conversion unit O / E.

(B) Second Embodiment In the second embodiment, a method of setting a backup path that enables quick switching from a working path to a protection path in the event of a failure, and a switching method at that time are described. explain.

In the present embodiment, an example of a network configuration as shown in FIG. 4, that is, a configuration of a double ring type network will be described. FIG. 5 shows an example of a hardware configuration suitable for applying the node configuration described in the first embodiment to the network shown in FIG. FIG. 5 is a hardware configuration example of an optical ADM (Add Drop Multiplexer).

First, the hardware configuration of the node device shown in FIG. 5 will be described. In FIG. 5, A01 and A11 denote wavelength separating means, A02 and A12 denote wavelength multiplexing means, and SW
1 to SW8 denote optical signal exchange means, E / O denotes electro-optical conversion means, O / E denotes opto-electric conversion means, C1 and C2 denote optical branching means, and D1 denotes fault detection means. Note that R
0 and R1 represent transmission paths.

As shown in FIG. 5, an optical wavelength multiplexed signal input from a transmission line of a network is separated into signals for each wavelength by wavelength separating means A01 or A11. The separated signal is output to a path (optical fiber) corresponding to each wavelength, and the two-input two-output optical signal switching means SW5
SW8 is input to one of the two input ports provided. The optical signals input in this way are converted into wavelength multiplexing means A02 by switching of each optical signal switching means.
The signal is output to A12 or the optical signal exchange means SW3 and SW4. On the other hand, to the other of the two input ports provided in the optical signal exchange means SW5 to SW8, an optical signal exchange means SW1 or SW1 through which an optical signal addressed to another node is passed from the own node. SW2.

The optical signal addressed to the own node out of the output of the optical signal switching means SW3 or SW4 is input to the optical splitting means C1 and C2 and split, one of which is sent to the O / E.
The other is configured to be output to the failure detection means D1. As described above, the number of the failure detection means D1 installed in the node in the present embodiment is also one.

Hereinafter, the path setting method and the switching method according to the present embodiment will be described with reference to the network configuration shown in FIG.
In FIG. 4, N1 to N5 represent nodes, and R0 and R1 represent transmission paths. As shown in FIG. 4, the nodes N1 to N5 are connected in a ring shape by a transmission line having a duplex configuration. The optical signal transmitted by the transmission line R0 is transmitted clockwise, and the optical signal transmitted by the transmission line R1 is transmitted counterclockwise.

In this case, consider the case where the optical path is set as follows. In FIG. 4, consider a path when the source node is node N1 and the destination node is node N3.

Here, assuming that the working path is the optical path P1-3 passing through the transmission line R0, the optical path RP1-3 passing through the transmission line R1 is set as the protection path. At this time, the working path P
1-3 are set to pass through the nodes N1-N2-N3 clockwise in the figure. On the other hand, the backup path RP1-3
Correspond to nodes N1-N5-N4-N3 counterclockwise in the figure.
Is set to go through. Needless to say, there is no overlap on the route between the working path and the protection path. Also,
In the present embodiment, the working path P1-3 and the protection path R
The same wavelength is assigned to P1-3.

First, the working path P1-3 will be considered.
When each node shown in FIG. 4 has the node configuration shown in FIG. 5, the optical signal of the wavelength assigned to the working path passes through one of the optical signal switching means SW5 and SW6 shown in FIG. Here, it is set so as to pass through the optical signal exchange means SW5.

In this case, each node located on the path of the working path P1-3 is in the following connection state. First, at the node N1 serving as the source node, the optical signal exchange means SW1
Is connected to the electro-optical conversion means E / O, the output of the optical signal exchange means SW5 is connected to the wavelength multiplexing means A02,
In addition, in the optical signal exchange means SW5, the electro-optical conversion means E
/ O and the wavelength multiplexing means A02 are connected.

Further, at the node N2 serving as a relay node,
The input port of the optical signal exchange means SW5 is connected to the wavelength separation means A0.
1 shows a state where the output port is connected to the wavelength multiplexing means A02.

At the node N3 serving as the destination node, the input port of the optical signal exchange means SW5 is connected to the wavelength demultiplexing means A01, and the output port is connected to the optical signal exchange means SW3. Conversion means O / E
Set to be ready for output. The above is the connection state of the working path.

On the other hand, in the nodes located on the route of the backup path RP1-3, the switches of the optical signal exchange means SW5 for exchanging the wavelength assigned to the transmission line R1 are all set in a state of passing through the nodes in advance. Use a configuration to set.

For example, in FIG. 5, the wavelength separating means A1
Among the optical signals separated by 1, the optical signal of the wavelength assigned to the protection path PR1-3 (the same wavelength as the working path)
Assuming that the setting is made so as to pass through the optical signal exchange means SW7, all the nodes are set so that the input port of the optical signal exchange means SW7 is connected to the wavelength demultiplexing means A11 and the output port is connected to the wavelength multiplexing means A12. Then, the optical signal switching means SW7 is set so that the signal separated by the wavelength separating means A11 is output to the wavelength multiplexing means A12 through the optical signal switching means SW7.

The operation of switching the working path to the protection path when a failure occurs will be described below on the premise of such a connection state.

For example, the current working path P1-3 (N1-N
2-N3) (nodes N1 and N2)
It is assumed that a failure has occurred in the link L12) connecting. Also in this case, the failure detecting means D1 of the node N3, which is the destination node, which monitors the presence or absence of a failure in the working path, detects the occurrence of the failure.

Here, the destination node (node N3) performs an operation of switching the input of the optical signal to the protection path side.
That is, the input port of the optical signal exchange means SW3 is connected to the optical signal exchange means SW5 on the transmission line R0 side connected to it.
To switch the connection to the optical signal exchange means SW7 on the transmission line R1 side.

Next, the destination node (node N3) reports the occurrence of the failure detected by itself to the source node (node N1) of the corresponding path by using an existing well-known technique (control channel, dedicated control line, etc.). Notice.

Upon receiving the failure notification, the source node (node N1) switches the working path to the protection path. That is, the source node (node N1)
Performs an operation of switching the output port of the optical signal exchange means SW1 from the current output port (that is, the optical signal exchange means SW5) to the optical signal exchange means SW7 side. When the switching operation on the source node side is completed, the other nodes that are already located on the backup path RP1-3 are set to pass the optical path, and thus transmitted from the source node (node N1). The optical signal can be transmitted to the destination node N3 through the protection path RP1-3.

As described above, in the present embodiment, when setting the optical path, the switch of the node on the path of the backup path is set in a state of passing through the node in advance, so that when a failure occurs, the destination By simply switching the switches of the optical signal switching means in each of the node and the source node, the switching from the failed working path to the protection path can be completed.

This means that switching to the backup path can be performed more quickly than switching a large number of nodes in the path of the backup path.

(C) Third Embodiment In the third embodiment, when a node having the configuration described in the second embodiment is connected to a double ring network, switching between the working path and the protection path is performed. An optical path setting method that does not require wavelength conversion will be described.

Here, description will be made on the premise of the ring network shown in FIG. In FIG. 4, R0 and R1 represent transmission paths, respectively, and N1 to N5 represent nodes. As shown in FIG. 4, each node is connected in a ring shape by a transmission path. The transmission path R0 is clockwise and the transmission path R1 is
Transmit an optical signal in a counterclockwise direction. Also, as in the second embodiment, each node in FIG. 4 has the configuration shown in FIG.

When setting an optical path in such a network, the optical path may be set by the following method. First, optical wavelengths usable in the network system are divided into two groups A and B. Then, the transmission path R0
, A working path is set using the optical wavelength of one group, for example, group A, and a working path is set for the transmission line R1 using the optical wavelength of the other group, for example, group B.

For example, in the case of a ring network having five nodes, an example of setting an optical path by the above-described wavelength assignment method is as follows.
As shown in FIG. FIG. 6 illustrates an example in which a bidirectional path is assigned to each node in a full mesh.

In the case of FIG. 6, the usable light wavelengths are λ1 to λ.
6 is assumed. The wavelengths belonging to group A among them are λ1, λ2, λ3, and the wavelengths belonging to group B are λ4, λ5, λ6.

In this case, for example, if an optical path connecting the node 1 and the node 3 is described as P1-3, the transmission path R0 has P1-3 and P3 as optical paths to which the wavelength λ1 is allocated. -5 and P5-1 are P1-2, P2-4 and P4- as optical paths to which the wavelength λ2 is assigned.
1 is an optical path to which the wavelength λ3 is assigned, P2-
3, P3-4, P4-5, and P5-2 are set.

Similarly, the transmission path R1 has P1-5, P5-3, P3-1 as optical paths to which the wavelength λ4 is allocated.
Are P1-4 as optical paths to which the wavelength λ5 is assigned,
P4-2 and P2-1 set P5-4, P4-3, P3-2, and P2-5 as optical paths to which the wavelength λ6 is assigned.

At this time, the backup path paired with each of the working paths is set as follows. First, the protection path for the working path (the working path of R0 using λ1, λ2, λ3) set to the transmission line R0 is set to the optical fiber R1, and the working path (λ4, λ5, λ6) set to the optical fiber R1 is set to the protection path. The protection path for the working path of R1 to be used) is set to R0. The same wavelength is assigned to the working path and the protection path.

For example, the working path P1-3 set by allocating the wavelength λ1 on the transmission line R0 is connected to the node N1
-N2-N3, the backup path RP1-3 is connected to the nodes N1-N on the transmission line R1.
This is set by assigning the wavelength λ1 to the route 5-N4-N3.

Similarly, the backup path RP of the working path P3-5
As for 3-5, the nodes N3-N2- on the transmission line R1
This is set by assigning the wavelength λ1 to the path N1-N5. Similarly, the backup path RP5 of the working path P5-1
-1, the nodes N5-N4-N on the transmission line R1
This is set by assigning the wavelength λ1 to the route 3-N2-N1. That is, a plurality of working paths share the wavelength of the protection path. Similarly, the protection paths for the other working paths are set using the same wavelength of different transmission paths as shown in FIG.

A method of switching paths when a failure occurs in the link L34 connecting the nodes N3 and N4 will be described with reference to the above setting example. Here, the operation in the case where the working path is shifted to the protection path will be described using the path P35 from the node N3 to the node N5 as an example.

In each node, the wavelength λ1 of the transmission line R0 passes through the optical signal switching means SSW5 of FIG. At the source node N3, the optical signal passing through the working path P35 is transmitted from the electro-optical conversion unit E / O to the wavelength multiplexing unit A02 via the optical signal switching units SW1 and SW5, multiplexed by the wavelength multiplexing unit A02 and output. Is done.

The optical signal output from the source node N3 reaches the node N4 via the link L34. At the node N4, the optical signal input from the link L34 is separated for each wavelength in the wavelength separating means A01, and the signal is separated via the optical signal switching means SW5 into the wavelength multiplexing means A02.
Is transmitted to This signal is multiplexed with a signal of another wavelength by the wavelength multiplexing means A02 and output.

The optical signal output from the node N4 reaches the node N5 via the link L45. Destination node N
In 5, the optical signal input from the link L45 is separated for each wavelength by the wavelength separating means A01, and the signal is output to the optical signal switching means SW3 via the optical signal switching means SW5. This signal is transmitted to the optical signal exchange means SW
3 is output to the photoelectric conversion means O / E and processed in the node.

Assume that a failure has occurred in the link L34. At this time, the failure detection means D1 of the destination node N5
It is determined that a failure has occurred in the signal of the working path P3-5. At this time, the node N5 switches so that the input port of the optical signal exchange means SW3 on the transmission line R0 side is connected to the optical signal exchange means SW7 on the transmission line R1 side, and notifies the failure notification to the source node N3 of the path P3-5. Notify. This notification is notified using an existing well-known technology as described.

When the node N3 which is the source node of the path P3-5 receives the failure notification of the path P3-5, the node N3 changes the output port of the optical signal exchange means SW1 from the optical signal exchange means SW5 side of the transmission path R0 to the transmission path. Optical signal exchange means SW on R1 side
It operates to switch to the 7 side.

The above operation is the only operation necessary for switching between the working path and the protection path. As described in the second embodiment, the input / output ports of the optical signal switching means SW7 of the relay nodes N2 and N1 of the backup path RP3-5 are:
It is assumed that the wavelength separation means A11 and the wavelength multiplexing means A12 are set in advance so as to be connected to each other.

As described above, in the setting of the optical path of the double ring, the usable wavelengths are divided into two groups A and B, and the working path of the first transmission line is set to the group A. , The working path of the second transmission line is allocated to the wavelength of the group B, and the protection path for the working path of the first transmission line is allocated to the wavelength of the group A of the second transmission line. By allocating the protection path for the working path of the second transmission path to the wavelength of the group B of the first transmission path, the working path and the protection path can have the same wavelength.

Therefore, even when the path is switched when a failure occurs, there is no need to change the wavelength at all, and the path can be switched to the backup path only by switching the switches of the optical signal exchange means of the source node and the destination node of the target path.

As described above, in the present embodiment, the path can be switched by a simple operation, so that it is expected that the time until the failure recovery is shortened. further,
Since the switching to the backup path can be performed without identifying the location of the failure, the path can be switched more quickly.

Further, by sharing the wavelength assigned to the protection path among a plurality of working paths, the number of wavelengths required for the system can be reduced.

Also, since the same wavelength can be used for the working path and the protection path, a node can be created with a simpler configuration.

(D) Other Embodiments In the above-described second embodiment, in the 2-input × 2-output optical signal switching means, the wavelengths assigned to the backup path are set in advance in a state of passing through the node. Although the description has been made in such a manner, the configuration of the optical signal exchange means is not limited to this. That is, even when a node is equipped with a larger optical signal switching means, the wavelength assigned to the backup path is set to pass through the node, and when a failure occurs, the optical signal switching between the source node and the destination node is performed. A desired switching operation may be realized only by switching the means.

In the above-described second embodiment, a method of switching paths in a network having a double ring configuration has been described. However, this path switching method is not limited to a double ring network. That is,
The same can be applied to a lattice network, a mesh network, and other networks. For example, for a given network, consider a closed loop path connecting a source node and a destination node, set a working path and a protection path for the path, and set a protection path to pass through a node located on the path. By doing so, the same operation as in the second embodiment can be performed.

Further, in the second embodiment, the case where the same wavelength is used for the working path and the protection path has been described. However, the same can be applied to the case where different wavelengths are set. In this case, a wavelength conversion operation is required when the path is switched, but only that operation is added. As in the second embodiment, the working path is protected only by switching the connection between the source node and the destination node. You can switch to a pass.

Also, in the third embodiment, the method for setting the working path and the protection path and the method for switching the paths applied to the double ring network system have been described. However, the present invention is not limited to this, and can be applied to any network as in the second embodiment.

In each of the above-described embodiments, the case where all are applied to the optical wavelength division multiplexing network has been described. The present invention can be similarly applied to a network for transmitting data. That is, it is possible to shorten the switching time from the working path to the backup path, to reduce the hardware configuration required for the node device, and the like.

[0079]

(A) As described above, according to the first aspect of the present invention, when a working path and its protection path are previously set on a network, usable wavelengths are classified into a plurality of groups, and The groups are assigned for setting the working path in the different transmission media, and the respective groups are transmitted to each other for setting the protection path in a transmission medium different from the transmission medium assigned for setting the working path. By deciding the assignment so that the medium does not overlap, it is not necessary to switch the wavelength when switching.

(B) According to the second invention, in the first invention, the same wavelength is assigned to the working path and its protection path. With this assignment, it is not necessary to switch the wavelength when switching is performed.

(C) According to the third aspect, in the first or second aspect, the working path can be set bidirectionally between the nodes.

(D) According to the fourth aspect of the present invention, the working path and its backup path are set on the network in advance, so that each of them does not include the path used by the other. When a route has been set, the failure detection of the working path is performed only at the destination node of each path, and when the occurrence of a failure is detected, the destination node switches the path from the working path to the protection path. Is not required, a failure detection operation on the relay node is not required, and a path switching method capable of promptly switching paths can be realized.

(E) According to the fifth invention, in the fourth invention, the failure detection of the working path is executed on the lead-in line to the destination node itself,
No matter where a failure occurs on the path of the working path, it can be detected as a failure without exception.

(F) According to the sixth aspect, in the fourth or fifth aspect, each of the nodes located on the route of the backup path sets a route in advance so that the backup path passes through itself. Is performed, the switching from the working path to the protection path can be realized only by switching between the source node and the destination node.

(G) According to the seventh aspect of the present invention, when the working path and its backup path are set in advance on the network, the working path to be set and its backup path have the other path on the other side. As a node device in a network in which a route is set so as not to include the route used by the node, whether a failure has occurred in any place on the working path from the signal state on the service line to the own node In this case, it is possible to achieve both the function of switching to the backup path based on the detection of the failure of the working path and the miniaturization of the hardware configuration.

(H) According to the eighth aspect, when the node device according to the seventh aspect is located on the path of the backup path, the path is set such that the backup path passes through the path. Is performed, the switching from the working path to the protection path can be realized only by switching between the source node and the destination node.

(I) Further, according to the ninth aspect, as the node device according to the seventh or eighth aspect, the same wavelength is assigned to the working path and its protection path, thereby executing the switching. In this case, it is not necessary to switch the wavelength.

(J) According to the tenth aspect, when a working path and its backup path are previously set on a network as a node device, usable frequency bands are classified into a plurality of groups, Each group is assigned for setting a working path in a different transmission medium, and each group is set for a protection path in a transmission medium different from the transmission medium assigned for setting the working path.
In addition, by using a device including a path assignment determining unit that determines assignment so that transmission media do not overlap each other in each group, it is not necessary to switch frequency bands when switching is performed.

(K) In the eleventh aspect of the present invention, the switching is performed by allocating the same frequency band to the working path and its protection path as the node device in the tenth aspect. In this case, it is not necessary to switch the frequency band.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a functional block configuration of a node device used in a first embodiment.

FIG. 2 is a diagram illustrating an example of a network.

FIG. 3 is a diagram illustrating a conventional example of a node device.

FIG. 4 is a diagram illustrating an example of a double ring network.

FIG. 5 is a diagram illustrating a functional block configuration of a node device used in the second embodiment.

FIG. 6 is a diagram illustrating a setting example of a working path and a protection path described in a third embodiment.

[Explanation of symbols]

A1, A01, A11 ... wavelength separation means, A2, A02,
A12: wavelength multiplexing means, SW1 to SW8: optical signal switching means, E / O: electric-optical conversion means, O / E: photoelectric conversion means, C1 to C4: optical branching means, D1: failure detection means.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5K002 DA02 DA04 DA09 DA11 EA05 EA33 5K014 AA01 AA04 CA06 FA01 HA01 HA10 5K030 GA04 JA01 JL03 JT10 KX23 LA17 LC11 MA01 MB16 MB20 MD02 MD07 5K031 AA08 BA06 CB12 DA17 DB12 EA01 EA01 EB01 EA01 EB02 BB04 CC03 KK16 KK31 LL07

Claims (11)

[Claims] When a working path and its protection path are previously set on a network, usable wavelengths are classified into a plurality of groups, and each group is assigned for setting a working path in a different transmission medium. The allocation is determined for setting a backup path in a transmission medium different from the transmission medium to which each group is allocated for setting the working path, and in such a manner that transmission media do not overlap each other in each group. Path setting method. 2. The path setting method according to claim 1, wherein the same wavelength is assigned to the working path and its protection path. 3. The path setting method according to claim 1, wherein the working path is set bidirectionally between the nodes. 4. When a working path and its backup path are set in advance on a network, and these paths are set so that each of the paths does not include the other path to be used, the working path is used. Path failure detection is performed only at the destination node of each path, and when a failure is detected, the destination node instructs switching of the path from the working path to the protection path. Path switching method. 5. The path switching method according to claim 4, wherein the failure detection of the working path is performed on a drop-in line to the destination node itself. 6. The path switching method according to claim 4, wherein each node located on the path of the backup path sets a path in advance so that the backup path passes through itself. Path switching method. 7. When a working path and its backup path are previously set on a network, the working path to be set and its backup path are routed so that each path does not include the other used path. Node device in a network in which the setting of (1) is performed, and includes only a failure detection unit that detects whether a failure has occurred in any place on the working path from a signal state on a service line to the own node. A node device characterized by the above-mentioned. 8. The node device according to claim 7, wherein when the node device is located on the route of the backup path, the node device sets the route so that the backup path passes through the node device. 9. The node device according to claim 7, wherein the same wavelength is assigned to the working path and its protection path. 10. When a working path and its protection path are previously set on a network, usable frequency bands are classified into a plurality of groups, and each group is allocated for setting a working path in a different transmission medium. In addition, a path assignment for determining an assignment for setting a backup path in a transmission medium different from the transmission medium to which each group is assigned for setting a working path, and in such a manner that transmission media do not overlap with each other in each group. A node device comprising a determination unit. 11. The node device according to claim 10, wherein the same frequency band is allocated to the working path and its protection path.