JP3444231B2 - Wavelength ring system and method of housing in fiber - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength ring system capable of recovering from a failure which constitutes a communication network,
In particular, the present invention relates to a wavelength ring system based on a wavelength multiplexing technique and a method of accommodating the same in a fiber.

[0002]

2. Description of the Related Art In a communication network in which service reliability is highly demanded, a ring system is used for the purpose of securing a communication service by bypassing a failure at high speed. In 1992, published by Artech House (Song Ho Woo) "Fiber Network Service Survivability" (Tsong-Ho Wu, Fiber Network Se)
Rvice Survivability, 1992, Artech House), a ring system is an add-drop multiplexer that adds / drops a channel to a fiber.
It is formed by connecting a tip lexer (ADM) and a fiber in a ring shape.

FIG. 7 shows the topology of a communication network in which a ring system is installed. This network is composed of nodes 1 (101 to 110) and spans 2 (201 to 202), and the ring system is a closed circuit 3 (31 to 31) composed of nodes 1 and span 2.
It is installed at the position 33). At this time, the above-mentioned ADM and fiber respectively include the nodes 1 (101 to 110) and the spans 2 (201 to 201) that constitute the closed circuit 3 (31 to 33), respectively.
202).

In recent years, it has been realized to set a plurality of wavelength channels in one fiber based on the wavelength multiplexing technique for the purpose of cost-effectively increasing the communication capacity. As a wavelength multiplexing ring system based on this wavelength multiplexing, there is a system that maintains a service by setting a spare wavelength channel and switching to it when the current wavelength channel is affected by a failure such as fiber breakage. ,
“Bi-directional Wavelength Path Switched Ring, NE
C Research & Development vol.40, no.1, January 1
999 ". Fig. 8 shows the configuration of this wavelength division multiplexing ring system.

The wavelength multiplexing ring system shown in FIG. 8 includes a fiber 5 and a wavelength add / drop multiplexer (optical add / drop multiplexer) for adding / dropping a wavelength channel to / from the fiber 5.
r: OADM) 4. Where OADM
4 (41 to 46) and fiber 5 (501 to 508)
Nodes 1 (101 to 110) and spans 2 (201 to 2) forming the closed circuit 3 (31 to 33) shown in FIG. 7, respectively.
02), respectively, to form a ring system. For example, the OADMs 41 to 46 shown in FIG. 8 are installed in the nodes 101 to 106 shown in FIG. 7, respectively. Here, in the span 201 shown in FIG. 7, as shown in FIG. 8, four fibers 505 and 506 are provided in the clockwise clockwise direction, the preliminary clockwise direction, the current counterclockwise direction, and the preliminary counterclockwise direction, respectively. , 503, and 504 are installed, and the span 202 also includes four fibers, 50 fibers each.
1, 502, 507, 508 are installed. The fiber 5 thus installed in each span 2 is OA at each node 1.
Since it can be considered that they are connected by the DM 4 and constitute four fiber rings as a whole, such a system is hereinafter particularly referred to as a fiber ring system 6 (601).

FIG. 9 shows an OADM 4 installed in each node 1 in the fiber ring system 601 shown in FIG.
It is the figure which showed the inside. The OADM 4 includes an element switch 7 (701 to 732) and a wavelength demultiplexer 8 (801 to 8).
04) and the wavelength division multiplexer 9 (901 to 904). In FIG. 9, in particular, the OADM 42 in FIG.
Focusing on, the fiber 5 it terminates is shown.
The number of wavelength multiplexes per fiber is 32, and the element switches 701 to 732 are installed corresponding to the respective wavelengths. These are in the four fibers 501 to 50
4 have as input the wavelength sections to which the same wavelengths are respectively assigned,
It has as an output a wavelength section to which the same wavelengths are assigned up to 8. Here, the wavelength section is a physical link that transmits an optical signal at a wavelength assigned in a fiber 5 installed on a span 2 between adjacent OADMs 4, and a wavelength channel is set between a pair of nodes. They are connected by the OADM 4 installed in the node 1 through which they are connected. Here, the wavelength sections used for setting the working and protection wavelength channels are called the working wavelength section and the protection wavelength section, respectively.

As shown in FIG. 10, focusing on the element switch 7 and the working and spare wavelength sections for the same wavelength in FIGS. 8 and 9, the same wavelength is assigned by the element switch 7 from the fiber ring system 601. A ring system constructed by coupling working and spare wavelength sections onto a ring can be retrieved. This is especially called a wavelength ring system. FIG. 10 shows the wavelength (λ
8 shows the wavelength ring system 1001 taken out from the fiber ring system 6 focusing on 8). Here, the element switches 751, 708, 753, 754, 7
55 and 756 are respectively OADM4 shown in FIG.
1, 42, 43, 44, 45 and 46 are included. As shown by the thick solid line in FIG. 10, the setting of the working wavelength channel 1410 is realized by combining the set working wavelength sections with the element switch 4. In the conventional wavelength ring system 10, the working wavelength section and the spare wavelength section are set between all adjacent element switches in the system regardless of whether the working wavelength channel 14 is set or not, and the wavelengths assigned to them are set. Are all the same.

FIG. 11 shows a failure recovery operation when the working wavelength channel is affected by a failure in the conventional wavelength ring system 1001 shown in FIG. In FIG. 11, the working wavelength channel 1410 (numbered in both clockwise and counterclockwise directions) is set as indicated by a thick solid line on the side of the element switches 708 to 754 viewed in the counterclockwise direction. . As shown in FIG. 11, when a failure occurs between the element switches 708 and 753, the spare wavelength channel 1501 is indicated by a thick broken line on the clockwise side from the element switches 708 to 754 as shown by a thick broken line.
(Numbered clockwise and counterclockwise together) is set, and element switches 708 and 754 are set.
Switches the working wavelength channel 1410 to this.

FIG. 12 shows the wavelength ring system 1 of FIG.
The internal configuration of the element switch 7 is shown by taking the element switch 708 in 001 as an example. The element switch 7 is composed of a switch matrix 11 for adding / dropping wavelength channels, an electro-optical wave converting device 12, and an electro-optical wave converting device 13. The switch matrix 11 changes the connection between the input and the output by an electric signal. The lightwave electrical conversion device 12 performs conversion into an electrical signal that can be processed by the switch matrix 11. The electro-optical wave converter 13 includes a switch matrix 11
The electrical signal handled inside is converted into an optical signal having a wavelength to be added / dropped to / from the fiber 5. In FIG. 12, the element switch 708 performs conversion into an optical signal having a wavelength λ0 assigned to a wavelength channel to be branched and λ8 assigned to each wavelength section. The arrows shown in the switch matrix 11 indicate the switch matrix 11 when the working wavelength channel 1410 is switched to the spare wavelength channel 1501 when a failure occurs between the element switches 708 and 753, as shown in FIG. The switching operation in FIG. In the element switch 708, since the working wavelength section is not set in the direction 751 from the element switch 708, there is a port in the switch matrix 11 in which wavelength channels are not added or dropped.

FIG. 13 shows the closed circuits 31, 32 and 3 shown in FIG.
3, the fiber ring system 602, 603, 604
FIG. 3 is a diagram showing an inter-ring connection network formed by installing each of the above. Here, for simplification, only the fiber 5 around one direction is shown. The working wavelength channel 14 is provided between different nodes 108 and 107 that do not belong to the same closed circuit 3.
When setting 03 and 1404 as shown in FIG. 13, each channel needs to pass through a plurality of fiber ring systems 6 installed in different closed circuits 3. For the working wavelength channel 1403, the nodes 101 and 106
Further, regarding the working wavelength channel 1404, the working wavelength sections belonging to different fiber ring systems 6 are connected at the nodes 103 and 104, respectively.

[0011]

As described above, in the conventional wavelength ring system, the working wavelength section and the spare wavelength section are provided between all the adjacent element switches regardless of whether the working wavelength channel is set or not. It is set. Moreover, since each wavelength section is assigned the same wavelength, they must be accommodated separately in the four fibers set up between the adjacent OADMs on the closed path. As a result, setting the wavelength section in the fiber is wasteful. For example, in FIG. 13, if an attempt is made to set working wavelength channels 1403 and 1404 on different paths between nodes 108 and 107, no wavelength will be assigned to this wavelength channel in the working fibers of spans 201 and 202. Absent. Therefore, the use efficiency of the expensive fiber is poor, and the wavelength resource is wasted.

The present invention has been made in view of the above circumstances, and the wavelengths to be used by the set wavelength section are independently assigned to each wavelength section.
By accommodating the working wavelength section and the spare wavelength section that compose the wavelength ring system in the same fiber, or by accommodating the wavelength sections included in different wavelength ring systems in the same fiber, the use efficiency of the fiber is increased and the same demand is met. It is an object of the present invention to provide a wavelength ring system and a method of accommodating the fibers, which enables accommodation with a smaller number of fibers.

[0013]

Means for Solving the Problems] Wavelength ring system according to claim 1 to solve the above problems, a wavelength ring system to form a closed, installed in the wavelength for each node of said closed path Wavelength channel to ring system
Channel and wavelength channel from the wavelength ring system.
Channel branching element switches and clockwise and counterclockwise working wavelength sections and standby wavelength sections set between adjacent element switches on the closed circuit, and the set wavelength sections are used. The wavelength to be assigned is independently assigned to each wavelength section, and when the working wavelength channel formed by connecting the working wavelength sections to the element switch is affected by a failure, the wavelength is assigned through the element switch. A spare wavelength channel is formed by connecting spare wavelength sections, and the element switch terminating the working wavelength channel affected by the failure performs the failure recovery by switching to the spare channel.
The wavelength ring system according to claim 2 is the system according to claim 1, wherein when setting the wavelength section, only a working wavelength section necessary for setting at least one working wavelength channel is set and set. Further, it is characterized in that only a spare wavelength section necessary for setting a spare channel necessary for failure recovery is set for each of the working wavelength channels. In the wavelength ring system according to claim 3, in the system according to claim 1, the wavelength assigned to each set working wavelength section and the wavelength assigned to each set spare wavelength section are the same. Is characterized by. A wavelength ring system according to a fourth aspect is the same as the third system according to the third aspect, wherein the wavelengths assigned to the working wavelength sections and the spare wavelength sections are the same.

[0014] The method accommodates for the wavelength ring system fibers according to claim 5, wavelength forms a closed Ringushisu
A method of accommodating a system in a fiber , the wavelength channel being installed in each node of the closed circuit and connected to the wavelength ring system.
Channel and wavelength channel from the wavelength ring system.
Channel branching element switches and clockwise and counterclockwise working wavelength sections and standby wavelength sections set between adjacent element switches on the closed circuit, and the set wavelength sections are used. Wavelengths to be independently assigned to each wavelength section, and when the working wavelength channel formed by connecting the working wavelength section to the element switch is affected by a failure, the spare wavelength section is connected via the element switch. To configure a spare wavelength channel,
The same wavelength ring system is configured in a communication network system in which a wavelength ring system that performs failure recovery by switching to the protection channel by an element switch that terminates the working wavelength channel affected by the failure is installed in each of the closed paths. The working wavelength section and the spare wavelength section are accommodated in the same fiber. A method for accommodating a wavelength ring system in a fiber according to claim 6 is the method of forming a closed circuit in the wavelength ring system.
A method for accommodating a wavelength channel, which is installed in each node of the closed circuit and is inserted into the wavelength ring system.
Input and of wavelength channels from the wavelength ring system
It is composed of a branching element switch and a clockwise and counterclockwise working wavelength section and a spare wavelength section set between adjacent element switches on the closed circuit, and the set wavelength section should be used. Wavelengths are independently assigned to the respective wavelength sections, and when the working wavelength channel formed by connecting the working wavelength sections to the element switch is affected by a failure, the spare wavelength section is connected through the element switch. A communication network system in which a wavelength ring system is installed in each closed circuit by configuring a backup wavelength channel according to the above, and by switching the element switch terminating the working wavelength channel affected by the failure to the backup channel In the different wavelength ring system It is characterized in that they contain that wavelength section in the same fiber.

With the above-mentioned configuration, the utilization efficiency of the fiber is improved with respect to the wavelength allocation in the wavelength ring system,
In order to set the required fiber length to be small, the wavelength λ to be used by the set wavelength section is independently assigned to each wavelength section. This establishes the working wavelength channel and assigns wavelengths only to the spare wavelength sections needed to recover it. Further, the working wavelength section and the spare wavelength section in the same wavelength ring system are assigned to the same fiber, and the wavelength sections in different wavelength ring systems are assigned to the same fiber. As a result, regarding the setting of the working wavelength section and the spare wavelength section, it is performed only between the adjacent element switches that respectively set the working wavelength channel and the spare wavelength channel, so when the number of demand pairs to be accommodated and the demand amount are small, It is possible to accommodate this with a smaller number of fibers. Also, by assigning the same wavelength λ common to both the working wavelength section and the spare wavelength section, these wavelength numbers can be used to identify the wavelength ring system installed in a certain closed loop. It also has the side effect of facilitating the management and operation of the system. Furthermore, as a result of independently assigning wavelengths to each wavelength section, it is possible to accommodate wavelength sections belonging to wavelength ring systems installed on different closed circuits in the same fiber, and even with the same wavelength ring system, they are The same wavelength can be shared in the spare wavelength section. Therefore, in the inter-ring connection network, when accommodating the same demand, the number of fibers can be reduced as compared with the conventional wavelength ring system.

[0016]

1 is a diagram showing the configuration of an embodiment of a wavelength ring system according to the present invention. The wavelength ring system 1601 shown in FIG. 1 is similar to the conventional wavelength ring system 1001 shown in FIG. 10 in that there are four wavelength sections for working and standby in the clockwise and counterclockwise directions between all adjacent element switches 761 to 766. However, the wavelength assigned to each wavelength section is different for each of the adjacent element switches 761 to 766. However, in order to facilitate management and operation,
The same wavelength is assigned to the wavelength sections in the clockwise direction and the counterclockwise direction for each of the working and protection switches between the same adjacent element switches. Between the element switches 762 and 764, a working wavelength channel 1410 (numbered in both clockwise and counterclockwise directions) is set as indicated by a thick solid line. By independently assigning the wavelength number to each wavelength section in this manner, it becomes possible to efficiently accommodate the wavelength ring system in the fiber.

FIGS. 2, 3, and 5 are diagrams showing the configuration of another embodiment of the wavelength ring system according to the present invention. All of them are clockwise and counterclockwise set between the same adjacent element switches. The same wavelength is assigned to the wavelength sections in each direction. Therefore, for convenience of explanation, unlike the clockwise and counterclockwise bidirectional wavelength sections shown in FIGS. 10 and 11,
Only the unidirectional wavelength section is shown.

The wavelength ring system 1 of the present invention shown in FIG.
In the embodiment of 602, the working wavelength channel 1405.
Is set between the element switches 772 and 774, so that the working wavelength section is a portion necessary for setting the channel, and the element switch 772 and the element switch 77 are
3 and the element switch 773 and the element switch 77.
It's only done during 4. Here, the wavelength numbers λ9 and λ10 are assigned to each. Also, the setting of the spare wavelength section is performed by setting the working wavelength channel 1
When the 405 is affected by the failure, the element switch 77
Since a spare wavelength channel is set on the route passing through 2, 771, 776, 775, and 774, and switching can be performed, the spare wavelength section is set only on the route as shown by the dotted line in FIG. . Here, wavelength numbers λ16, λ21, λ20, and λ19 are assigned to the respective spare wavelength sections. Thus, unlike the conventional wavelength ring system 10, by setting the wavelength section only between the adjacent element switches necessary for setting the wavelength channel, the wavelength resources can be efficiently used.

The wavelength ring system 1 of the present invention shown in FIG.
In an embodiment of 603, element switches 782-7
Counterclockwise side to 84, and element switch 78
The working wavelength channels 1406 and 1407 are set on the clockwise side from 6 to 785, respectively, and the working wavelength sections set for that are assigned the same wavelength λ8. The spare wavelength section
The working wavelength channels 1406 and 1407 are set between all adjacent element switches, as indicated by the dotted lines, so that they can be recovered in the event of a failure, respectively, but assigned to their respective spare wavelength sections. The wavelength numbers are all λ16. Thus, if the working wavelength section and the spare wavelength section each use a common wavelength in the same wavelength ring system 1603, it can be used for specifying the wavelength ring system, and thus management and operation becomes easier.

FIG. 4 is a structural example of element switches in the wavelength ring system 1603 shown in FIG. 3, in which wavelength numbers λ8 and λ16 are assigned and the element switch 7
It is shown that the working wavelength section and the spare wavelength section set on the counterclockwise side from 82 to 783 are accommodated in the same fiber 511 and 514. Element switch 782 includes fibers 511 and 51.
2 has the wavelength sections separated by the wavelength demultiplexers 851 and 852 respectively as input, and the wavelength multiplexer 9
51 and 952 are fibers 513 and 51, respectively.
As an output, it has a wavelength section to be multiplexed into four. The element switch 782 includes a switch matrix 11, an electro-optical wave converter 12, and an electro-optical wave converter 13. The electro-optical wave converting device 13 generates an optical signal having a wavelength assigned to each wavelength section. Here, the element switch 78
2 is used to set a working wavelength section for setting a working wavelength channel 1406 set between it and the element switch 784, and a spare wavelength channel when the working wavelength channel 1406 fails. Both spare wavelength sections have a clockwise direction from element switches 783 to 782, and an element switch 782.
To fibers 511 and 514, respectively, in the counterclockwise direction from 1 to 783. Further, an arrow indicates switching to the backup wavelength channel when the set working wavelength channel 1406 is affected by the failure.

FIG. 5 is a diagram showing the configuration of another embodiment of the wavelength ring system 1604 according to the present invention. Here, working wavelength channels 1408 and 1409 are set between the element switches 792 and 794 and between the element switches 796 and 795, respectively, and working wavelength sections are set only between the adjacent switches required for them.
The spare wavelength section is set only between adjacent element switches necessary to set the spare wavelength channel when the working wavelength channels 1408 and 1409 are affected by the failure. The same wavelength (λ8) is assigned to each of the working spare sections. This wavelength number can be used to identify the wavelength ring system, which makes management and operation easier.

FIG. 6 shows the closed circuit 31, 32, 33 shown in FIG.
Respectively to the wavelength ring systems 1605 and 16 of the present invention.
It is the figure which showed the inter-ring connection network formed by installing 06 and 1607. In each wavelength ring system, wavelength numbers λ8, λ16, and λ8 are commonly assigned to the set spare wavelength sections. As a result, fiber 510 contains the spare wavelength sections belonging to wavelength ring systems 1605 and 1606, and fiber 511 contains the spare wavelength sections belonging to wavelength ring systems 1606 and 1607. In order to set the working wavelength channels 1401 and 1402, the working wavelength section is set in the wavelength ring systems 1605, 1606, and 1607 to which the wavelength numbers λ16, λ8, and λ16 are respectively assigned, and the wavelength ring system 1605 is set. , 16
06 and 1607, the working wavelength section and the spare wavelength section are respectively connected to the fibers 515, 516 and 51.
Share 7. By sharing the fiber described above,
It is possible to reduce the number of fibers required for a given setting requirement of the wavelength channel.

[0023]

As described above, according to the present invention, the setting of the working wavelength section and the spare wavelength section is performed only between the adjacent element switches which set the working wavelength channel and the spare wavelength channel, respectively. When the number of demand pairs to be demanded and the demand amount are small, it is possible to accommodate them with a smaller number of fibers. Also, by assigning the same wavelengths common to the working wavelength section and the spare wavelength section, respectively, these wavelength numbers can be used to identify the wavelength ring system installed in a certain closed circuit, and the wavelength ring system Easy management and operation. For example, if the wavelengths assigned to the working section and the spare section are generally different, the set of wavelengths is assigned to the working section and the spare section. If the wavelengths are the same, that wavelength can be used to identify the wavelength ring system. Further, according to the present invention, when accommodating the same demand in the inter-ring connection network, the number of fibers can be reduced as compared with the conventional wavelength ring system. For example, when two working wavelength channels are set between the nodes 108 and 107 shown in FIG. 7, conventionally, in a network in which fiber rings are connected as shown in FIG. 13, the required number of fibers for both directions is 4 × 4. In the communication network system in which the present invention shown in FIG. 6 is used, the number of fibers is 20, which is less than half. The reason for this is that wavelengths for each wavelength section are independently assigned, and as a result, wavelength sections belonging to wavelength ring systems installed on different closed paths can be accommodated in the same fiber, and even in the same wavelength ring system This is because the same fiber can be shared by the wavelength section and the spare wavelength section.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of a wavelength ring system of the present invention.

FIG. 2 is a diagram showing the configuration of another embodiment of the wavelength ring system of the present invention.

FIG. 3 is a diagram showing a configuration of still another embodiment of the wavelength ring system according to the present invention.

FIG. 4 is a diagram showing an internal structure of an element switch in the embodiment of the wavelength ring system shown in FIG.

FIG. 5 is a diagram showing a configuration of still another embodiment of the wavelength ring system according to the present invention.

FIG. 6 is a diagram showing a network configuration formed by connecting the wavelength ring system of the present invention.

FIG. 7 is a diagram showing a topology of a communication network in which a conventional wavelength ring system is installed.

FIG. 8 is a diagram cited for explaining a conventional fiber ring system.

9 is a diagram showing an internal structure of a wavelength add / drop multiplexer (OADM) in the conventional fiber ring system shown in FIG.

FIG. 10 is a diagram showing a configuration of a conventional wavelength ring system.

FIG. 11 is a diagram cited to show a failure recovery operation in the conventional wavelength ring system.

FIG. 12 is a diagram showing an internal structure of an element switch in a conventional wavelength ring system.

FIG. 13 is a diagram showing a network configuration formed by connecting conventional wavelength ring systems.

[Explanation of symbols]

1 (101 to 110) ... node 2 (201, 202) ... Span 3 (31-33) ... Ring 4 (41 to 46) ... Wavelength division multiplexer (OADM) 5 (501 to 520) ... Fiber 7 (701 to 796) ... Element switch 8 (801-852) ... Wavelength separation device 9 (901-952) ... Wavelength multiplexer 11 ... Switch matrix 12 ... Light-wave converter 13 ... Electro-optical wave converter 14 (1401 to 1410) ... Working wavelength channel 15 (1501) ... Spare wavelength channel 16 (1601 to 1607) ... Wavelength ring system

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Claims (6)

(57) [Claims] 1. A wavelength ring system forming a closed circuit, the element switch being installed at each node of the closed circuit for inserting a wavelength channel into the wavelength ring system and branching the wavelength channel from the wavelength ring system. And a clockwise and counterclockwise working wavelength section and a backup wavelength section set between the element switches adjacent to each other on the closed circuit, and the wavelength to be used by the set wavelength section is set to each wavelength. Each section is independently allocated, and when the working wavelength channel formed by connecting the working wavelength sections to each other is affected by a failure, the spare wavelength section to which the wavelength is allocated is connected through the constituent switch. To form a spare wavelength channel by Wavelength ring system elements switch to terminate the wavelength channels and performs the failure recovery by switching to the protection channel. 2. In the wavelength section setting, only a working wavelength section necessary for setting at least one working wavelength channel is set, and a spare channel setting required for failure recovery is set for each of the set working wavelength channels. A wavelength ring system according to claim 1, characterized in that only the spare wavelength section for is set. 3. The wavelength ring according to claim 1, wherein a wavelength assigned to each set working wavelength section and a wavelength assigned to each set spare wavelength section are the same. system. 4. The wavelength ring system according to claim 3, wherein the wavelengths assigned to the working wavelength sections and the backup wavelength sections are the same. 5. A method for accommodating a wavelength ring system forming a closed circuit in a fiber, comprising: installing a wavelength channel into the wavelength ring system and inserting a wavelength channel into the wavelength ring system, the wavelength channel being installed in each node of the closed circuit. And a working wavelength section and a backup wavelength section in clockwise and counterclockwise directions set between the element switches adjacent to each other on the closed circuit, and the set wavelength section is used. Power wavelength is independently assigned to each wavelength section, and when the working wavelength channel formed by connecting the working wavelength section to the element switch is affected by a failure, the spare wavelength section is connected via the element switch. By configuring a spare wavelength channel, In a communication network system wavelengths ring system elements switch to terminate the wavelength channels for disaster recovery by switching to the protection channel, which are installed to the each closing, the working wavelength and the working wavelength sections that make up the same wavelength ring system A method of accommodating a wavelength ring system in a fiber, comprising accommodating spare wavelength sections having different wavelengths from the section. 6. A method of accommodating a wavelength ring system forming a closed circuit in a fiber, comprising: inserting a wavelength channel into the wavelength ring system and installing a wavelength channel from the wavelength ring system, the method being installed in each node of the closed circuit. And a working wavelength section and a backup wavelength section in clockwise and counterclockwise directions set between the element switches adjacent to each other on the closed circuit, and the set wavelength section is used. Power wavelength is independently assigned to each wavelength section, and when the working wavelength channel formed by connecting the working wavelength section to the element switch is affected by a failure, the spare wavelength section is connected via the element switch. By configuring a spare wavelength channel, In a communication network system in which a wavelength ring system that performs failure recovery by switching an element switch that terminates a wavelength channel to the backup channel is installed in each of the closed circuits, the different wavelength ring systems are configured and are different from each other.
A method of accommodating a wavelength ring system in a fiber, comprising accommodating wavelength sections to which different wavelengths are allocated in the same fiber.