[Technical Field]
[0001] The present invention relates to a wavelength multiplexer and to a
method and a program for identifying a failed portion, and more particularly
relates to a wavelength multiplexer and the like that can effectively identify a
failed portion.
10 [Background Art]
[0002] Photonic networks are networks that depend solely on optical
techniques (without converting an optical signal into an electrical signal) to
implement network functions such as transmission, multiplexing,
demultiplexing, switching, and path control. Even before the rise of the
15 photonic networks, optical fibers have been used for transmission paths and
optical amplifiers have been used for amplifying a signal, but circuit
switching has only been electrically achievable. More specifically, the
optical signal has had to be converted into an electrical signal. Thus, a
communication capacity in the network is limited by the performance of a
20 switching apparatus.
[0003] The electrical switching involves extremely large power consumption
in the apparatus, which increasingly rises with a higher communication speed
and a larger number of systems of transmission paths that can be contained.
To satisfy the demand for achieving both high speed communications and low
25 power consumption growing by time, optical switching techniques achieving
the switching by directly using the optical signal, without the need of the
conversion into an electrical signal, have currently been under vigorous study
and development.
[0004] Fig. 4 is a diagram illustrating the configuration of a wavelength
multiplexer 900 (colorless/directionless/contentionless reconfigurable optical
addldrop multiplexer (CDC ROADM)) according to a known optical switching
technique. The wavelength multiplexer 900 is connected to WDM routes 90 1,
902, and 903 as a plurality of systems of optical fiber lines, and inputs and
5 outputs an optical signal to and from each WDM route.
[0005] Each WDM route inputs and outputs a signal to and from the
transponders 921, 922, and 923 through a split-and-select module 910. The
transponders 921, 922, and 923 convert an electrical or optical signal
transmitted from each client into an optical or electrical signal. Paths
10 between the split-and-select module 910 and each of the transponders 921,
922, and 923 are referred to as a client contained path.
[0006] In Fig. 4, the three systems of WDM routes 901, 902, and 903 and the
three systems of transponders 921, 922, and 923 are illustrated due to the
limitation in the sheet size. Larger numbers of WDM routes and
15 transponders may be connected to the actual wavelength multiplexer 900.
Furthermore, the number of systems needs not to be the same between WDM
routes and transponders.
[0007] The split-and-select module 9 10 includes: optical couplers 9 1 1
corresponding to optical signals transmitted and received by the WDM routes;
20 and optical switches 912 corresponding to optical signals transmitted and
received by the transponders. Each optical signal received from the WDM
route 901 is split by a splitter 901a and each optical signal obtained by
multiplexing in a multiplexer 901 b is input to the WDM route 901. Similar
splitters 902a and 903a and multiplexers 902b and 903b are respectively
25 connected to the other WDM routes 902 and 903.
[0008] The optical signals output from the splitter 901a of the WDM route
901 are input to the optical coupler 911a, the multiplexer 902b of the WDM
route 902, and the multiplexer 903b of the WDM route 903. Similarly, the
optical signals output from the splitter 902a of the WDM route 902 are input
to the optical coupler 911b, the multiplexer 901b of the WDM route 901, and
the multiplexer 903b of the WDM route 903. The optical signals output from
the splitter 903a of the WDM route 903 are input to the optical coupler 911c,
the multiplexer 901b of the WDM route 901, and the multiplexer 902b of the
5 WDM route 902.
[0009] The multiplexer 901b of the WDM route 901 multiplexes the signals
output from the optical coupler 9 11 d, the splitter 902a of the WDM route 902,
and the splitter 903a of the WDM route 903, and outputs the resultant signal
to the WDM route 901. Similarly, the multiplexer 902b of the WDM route
10 902 multiplexes the signals output from the optical coupler 91 le, the splitter
901a of the WDM route 901, and the splitter 903a of the WDM route 903, and
outputs the resultant signal to the WDM route 902. The multiplexer 903b of
the WDM route 903 multiplexes the signals output from the optical coupler
91 If, the splitter 901a of the WDM route 901, and the splitter 902a of the
15 WDM route 902, and outputs the resultant signal to the WDM route 903.
[0010] The optical switches 912a to 912c each select one of the optical
signals output from the multiplexers 90 1 b to 903b of the WDM routes 901 to
903, and input the selected signal to the transponders 921 to 923. The
optical switches 912d to 912f each select one of the splitters 901a to 903a of
20 the WDM routes 901 to 903, and outputs the optical signal output from the
transponders 921 to 923 to the selected destination.
[0011] When an optical signal output from the splitter 901a of the WDM
route 901 is to be received by the transponder 921, the optical switch 912a
may select the optical signal transmitted from the optical coupler 91 1 a, so that
25 a drop path will be established. When an optical signal is to be transmitted
to the multiplexer 901b of the WDM route 901 by the transponder 921, the
optical switch 912d may select the optical coupler 911d as the destination of
the output optical signal, so that.an add path will be established.
[0012] The inventors of the present invention have already put such a
wavelength multiplexer 900 into market in 2011 (NPL 2) as an apparatus
supporting 100 Gbitls Ethernet (registered trademark), and the apparatus is
currently under technical development to achieve higher speed and larger
capacity.
5 [0013] Technical literatures related to the apparatus include: PTL 1
describing an optical node system that can achieve function enhancement and
troubleshooting in a network at a low cost by using n x n optical switches;
NPL 1 introducing recent trends in the photonic network described above; and
NPL 2 describing the wavelength multiplexer supporting 100 Gbitls Ethernet
10 that has been put into market by the inventors as described above.
[Citation List]
[Patent Literature]
[OO 141 [PTL 11: Japanese Patent Application Publication No. 200 1-2680 11
[Non Patent Literature]
15 [0015] [NPL 11: Kenichi Kitayama, "Technical trend of Photonic Network",
September 9, 201 1, [searched on July 9, 20121, SCAT LINE Vol. 87, Photonic
Internet Forum, (Support Center for Advanced Telecommunications
Technology Research Foundation), Internet

20 [NPL 21: "NEC Launches Network Failure Resistant, Non-Blocking Optical
Cross-Connect Transmission Apparatus for 100 Gbitls Transmission (Press
Release)", June 9, 201 1, [searched on July 9, 20121, NEC Corporation,
Internet
25 [Summary of Invention]
[Technical Problem]
[0016] Unfortunately, the wavelength multiplexer 900 requires a cumbersome
operation, involving a large amount of time and labor, when any of the
transmission systems fail. Specifically, the optical cable needs to be
connected/disconnected and the transmission system needs to be switched
manually to identify whether the failure has occurred at a portion before or
after the split-and-select module 9 10.
[0017] The technique disclosed in PTL 1 is for maintaining communications
5 upon occurrence of a failure by avoiding the failure and is not for identifying
the failed portion. Neither NPL 1 nor NPL 2 discloses a technique that could
solve the problem described above.
[0018] An object of the present invention is to provide a wavelength
multiplexer, and a method and a program for identifying a failed portion that
10 can effectively identify whether a failed portion is before or after a
split-and-select module.
[Solution to Problem]
[0019] To achieve the object, a wavelength multiplexer according to the
present invention is a wavelength multiplexer that is connected with and
15 provided between a plurality of systems or a single system of optical fiber
lines and a plurality of systems or a single system of optical transponders, and
inputs and outputs an optical signal to and from the optical fiber lines and the
optical transponders. The wavelength multiplexer includes: first optical
switches that output an optical signal input from the optical fiber lines to the
20 optical transponders; second optical switches that output an optical signal
input from the optical transponders to the optical fiber lines; and a local
optical loopback circuit that loops back and outputs an optical signal input
from any of the optical transponders to the side of that optical transponder.
[0020] To achieve the object, a method for identifying a failed portion
25 according to the present invention is a method for identifying a failed portion
executed by a module inspection unit included in a split-and-select module
included in a wavelength multiplexer. The split-and-select module is
connected with a plurality of systems of optical fiber lines and optical
transponders and inputs and outputs an optical signal to and from the optical
fiber lines and the optical transponders. The split-and-select module
includes: a local optical loopback circuit that loops back and outputs an
optical signal input from any of the optical transponders to the side of that
optical transponder; first optical switches that selectively output the optical
5 signal received from the optical fiber lines or the optical signal looped back
by the local optical loopback circuit to the optical transponders by an external
switching operation; second optical switches that selectively output the
optical signal received from the optical transponders to one system of the
optical fiber lines or the local optical loopback circuit by an external
10 switching operation; and the module inspection unit that operates in
accordance with an external operational instruction. The method includes:
controlling switching of the first optical switches so as to output the optical
signal looped back by the local optical loopback circuit to the optical
transponders; at the same time, controlling switching of the second optical
15 switches so as to output the optical signal received from the optical
transponders to the local optical loopback circuit; and then causing the optical
transponders to operate and emit the optical signal and determining whether
the optical transponders have received the optical signal looped back by the
local optical loopback circuit.
20 [0021] To achieve the object, a program for identifying a failed portion
according to the present invention is a program for identifying a failed portion
containing processes executed by a processor included in a module inspection
unit included in a split-and-select module included in a wavelength
multiplexer. The split-and-select module is connected with a plurality of
25 systems of optical fiber lines and optical transponders and inputs and outputs
an optical signal to and from the optical fiber lines and the optical
transponders. The split-and-select module includes: a local optical loopback
circuit that loops back and outputs an optical signal input from any of the
optical transponders to the side of that optical transponder; first optical
switches that selectively output the optical signal received from the optical
fiber lines or the optical signal looped back by the local optical loopback
circuit to the optical transponders by an external switching operation; second
optical switches that selectively output the optical signal received from the
5 optical transponders to one system of the optical fiber lines or the local
optical loopback circuit by an external switching operation; and the module
inspection unit that operates in accordance with an external operational
instruction. The processes include: switching of the first optical switches so
as to output the optical signal looped back by the local optical loopback
10 circuit to the optical transponders; at the same time, switching of the second
optical switches so as to output the optical signal received from the optical
transponders to the local optical loopback circuit; and then causing the optical
transponders to operate and emit the optical signal and determining whether
the optical transponders have received the optical signal looped back by the
15 local optical loopback circuit.
[Advantageous Effects of Invention]
[0022] The present invention can provide a wavelength multiplexer and a
method and a program for identifying a failed portion which has an excellent
feature'that can effectively identify whether a failed portion is before or after
20 the split-and-select module, with the configuration including a local optical
loopback circuit that loops back and outputs an optical signal input from any
of the optical transponders to the side of that optical transponder as described
above.
[Brief Description of Drawings]
25 [0023] [Fig. I] Fig. 1 is a diagram illustrating the configuration of a
wavelength multiplexer according to a first exemplary embodiment of the
present invention.
[Fig. 21 Fig. 2 is a flowchart illustrating processing for identifying whether a
failed portion is before or after a split-and-select module in the wavelength
multiplexer illustrated in Fig. 1.
[Fig. 31 Fig. 3 is a diagram illustrating the configuration of a wavelength
multiplexer according to a second exemplary embodiment of the present
invention.
5 [Fig. 41 Fig. 4 is a diagram illustrating the configuration of a wavelength
multiplexer according to a known optical switching technique.
[Description of Embodiments]
(First exemplary embodiment)
10 [0024] A first exemplary embodiment of the present invention is described
below with reference to Fig. 1.
The basic configuration of the present exemplary embodiment is
described, and then the detailed configuration will be described.
A wavelength multiplexer 100 according to the present exemplary
15 embodiment is a wavelength multiplexer that is connected with a plurality of
systems of optical fiber lines (WDM routes 101 to 103) and optical
transponders (transponders 21 to 23), and inputs and outputs an optical signal
to and from the optical fiber lines and the optical transponders. The
wavelength multiplexer 100 includes: first optical switches 12a to 12c that
20 output an optical signal input from the optical fiber lines to the optical
transponders; second optical switches 12d to 12f that output an optical signal
input from the optical transponders to the optical fiber lines; and a local
optical loopback circuit 13 that loops back and outputs an optical signal input
from any of the optical transponders to the side of that optical transponder.
25 [0025] The first optical switches 12a to 12c selectively output the optical
signal received from the optical fiber lines or the optical signal looped back
by the local optical loopback circuit to the optical transponders by an external
switching operation. The second optical switches 12d to 12f selectively
output the optical signal received from the optical transponders to one system
of the optical fiber lines or the local optical loopback circuit by an external
switching operation.
[0026] The wavelength multiplexer 100 further includes: optical couplers 11 a
to 1 lc that each branch an optical signal received from a corresponding one of
5 the optical fiber lines and output the resultant signal to each optical
transponder, and second optical couplers 1 ld to 1 l f that each multiplex an
optical signal received from a corresponding one of the optical transponders
and output the resultant signal to each optical fiber line.
[0027] The wavelength multiplexer 100 includes a module inspection unit 40
10 that, in accordance with an external operational instruction, switches the first
optical switches so as to output the optical signal looped back by the local
optical loopback circuit to the optical transponders; at the same time, switches
the second optical switches so as to output the optical signal received from the
optical transponders to the local optical loopback circuit; and then causes the
15 optical transponders to emit the opti,cal signal and determines whether the
optical transponders have received the optical signal looped back by the local
optical loopback circuit.
[0028] With this configuration, the wavelength multiplexer 100 can
effectively identify whether a failed portion is before or after a
20 split-and-select module 10.
The following describes the configuration in greater detail.
[0029] Fig. 1 is a diagram illustrating the configuration of the wavelength
multiplexer 100 (colorlessldirectionless/contentionless reconfigurable optical
addldrop multiplexer, CDC ROADM) according to the first exemplary
25 embodiment of the present invention. The wavelength multiplexer 100 is
connected to the WDM routes 101, 102, and 103 as a plurality of systems of
optical fiber lines, and inputs and outputs an optical signal to and from each
WDM route.
[0030] Each WDM route inputs and outputs a signal to and from the
transponders 21, 22, and 23 through the split-and-select module 10. The
transponders 2 1, 22, and 23 convert an electrical or optical signal transmitted
from each client into an optical or electrical signal. Paths between the
split-and-select module 10 and each of the transponders 21, 22, and 23 are
5 referred to as a client contained path.
[003 11 In Fig. 1, the three systems of WDM routes 10 1, 102, and 103 and the
three systems of transponders 21, 22, and 23 are illustrated due to the
limitation in the sheet size. Larger numbers of WDM routes and
transponders may be connected to the actual wavelength multiplexer 100.
10 Furthermore, the number of systems needs not to be the same between WDM
routes and transponders.
[0032] The split-and-select module 10 includes: the optical couplers 11 that
deal with optical signals transmitted and received by the WDM routes; and the
optical switches 12 that deals with optical signals transmitted and received by
15 the transponders. Each optical signal received from the WDM route 101 is
split by a splitter 101a and each optical signal obtained by multiplexing in a
multiplexer 10 1 b is input to the WDM route 10 1. Similar splitters 102a and
103a and multiplexers 102b and 103b are respectively connected to the other
WDM routes 102 and 903.
20 [0033] The optical signals output from the splitter 10 l a of the WDM route
101 are input to the optical coupler 1 la, the multiplexer 102b of the WDM
route 102, and the multiplexer 103b of the WDM route 103. Similarly, the
optical signals output from the splitter 102a of the WDM route 102 are input
to the optical coupler 1 1 b, the multiplexer 10 1 b of the WDM route 10 1, and
25 the multiplexer 103b of the WDM route 103. The optical signals output from
the splitter 103a of the WDM route 103 are input to the optical coupler 1 lc,
the multiplexer 101b of the WDM route 101, and the multiplexer 102b of the
WDM route 102.
[0034] The multiplexer 101 b of the WDM route 101 multiplexes the signals
output from the optical coupler 1 ld, the splitter 102a of the WDM route 102,
and the splitter 103a of the WDM route 103, and outputs the resultant signal
to the WDM route 101. Similarly, the multiplexer 102b of the WDM route
102 multiplexes the signals output from the optical coupler Ile, the splitter
5 101 a of the WDM route 101, and the splitter 103a of the WDM route 103, and
outputs the resultant signal to the WDM route 102. The multiplexer 103b of
the WDM route 103 multiplexes the signals output from the optical coupler
1 lf, the splitter 1 Ola of the WDM route 101, and the splitter 102a of the
WDM route 102, and outputs the resultant signal to the WDM route 103.
10 [0035] The configuration described above is the same as the wavelength
multiplexer 900 according to the known technique described above. The
split-and-select module 10 included in the wavelength multiplexer 100
according to the present exemplary embodiment further includes two optical
couplers 1 lg and 1 lh. The optical signals output from the optical coupler
15 1 l h are directly input to the optical coupler 1 lg. Thus, the optical couplers
1 lg and 11 h are also collectively referred to as a local optical loopback circuit
13.
[0036] The optical switches 12a to 12c each select one of the optical signals
output from the splitters 101 b to 103b of the WDM routes 101 to 103 and the
20 optical coupler 1 lg, and input the selected signal to the transponders 21 to 23.
The optical switches 12d to 12f each select one of the multiplexers 101a to
103a of the WDM routes 10 1 to 103 and the optical coupler 1 lh, and outputs
the optical signal output from the transponders 21 to 23 to the selected
destination.
25 [0037] A module inspection unit 40 is a microcomputer or a stand-alone
computer device that includes a processor 41 that mainly executes a computer
program, and is connected to the split-and-select module 10. When a user
instructs the module inspection unit 40 to perform inspection through an input
and output means 42, the processor 41 starts an inspection program to
function as an inspection means 43. The module inspection unit 40 further
includes a storage means, a communication means, and the like that are not
particularly required for describing the present invention and thus will not be
described in detail.
5 [0038] The inspection means 43 emits a control signal for instructing the
optical switches 12a to 12f to switch optical signals. The inspection means
43 also emits a control signal for instructing the transponders 21 to 23 to
output light to receive information indicating the strength, the wavelength,
and the like of the input optical signal from the transponders 21 to 23.
10 [0039] Fig. 2 is a flowchart illustrating processing for identifying whether a
failed portion is before or after the split-and-select module 10 in the
wavelength multiplexer 100 illustrated in Fig. 1. The inspection means 43
that has started the processing first switches among the optical switches 12d
to 12f so that the switch, corresponding to one of the transponders 2 1 to 23 as
15 the inspection target, outputs the optical signals output from the target
transponder to the optical coupler 11 h (the local optical loop back circuit 13)
(step S201).
[0040] In response to this process, the inspection means 43 switches between
the optical switches 12a to 12c so that the optical signals output from the
20 optical coupler 1 lg (the local optical loop back circuit 13) return to the input
side of the inspection target in the transponders 21 to 23 as the inspection
target (step S202). With these processes, a local side loopback for the
transponder as the inspection target is established.
[0041] The inspection means 43 then causes the inspection target in the
25 transponders 21 to 23 to output light (step S203), and thus determines whether
the optical signal returned through the local optical loopback circuit 13 is
input to the inspection target in the transponders 21 to 23 (step S204).
COO421 When the optical signal is failed to be input, the client contained path
before the split-and-select module 10 can be determined to have an
abnormality (step S20.5). When the optical signal is successfully input, the
WDM routes 101 to 103 after the split-and-select module 10 can be
determined to have an abnormality (step S206). Either of the determination
results is presented to the user through the input and output means 42 (step
5 S207), and thus the processing performed by the inspection means 43 is
terminated.
[0043] For example, whether the client contained path is appropriately
connected between the split-and-select module 10 and the transponder 21 can
be checked as follows. Specifically, the inspection means 43 performs the
10 switching in step S201 in such a manner that the optical switch 12d outputs
the optical signal, output from the transponder 21, to the optical coupler 11 h.
This output optical signal returns to the optical coupler l l g , and thus the
inspection means 43 performs the switching in step S202 in such a manner
that the optical switch 12a inputs this optical signal output from the optical
15 coupler 11 g to the transponder 2 1.
[0044] Thus, if the client contained path between the split-and-select module
10 and the transponder 21 has an abnormality, the output optical signal does
not return to the input side due to the incomplete optical loopback. Thus, it
is apparent that the client contained path has the abnormality. The client
20 contained paths between the other transponders 22 and 23 and the
split-and-select module 10 can be checked in a similar manner to see whether
there is an abnormality.
[0045] (Overall processing in first exemplary embodiment)
Next, the overall processing in the exemplary embodiment mentioned
25 above will be described.
A method for identifying a failed portion according to the exemplary
embodiment is executed by the module inspection unit 40 included in the
split-and-select module 10 included in the wavelength multiplexer 100. The
split-and-select module 10 is connected with a plurality of systems of optical
fiber lines and optical transponders and inputs and outputs an optical signal to
and from the optical fiber lines and the optical transponders. The
split-and-select module 10 includes: the local optical loopback circuit 13 that
loops back and outputs an optical signal input from any of the optical
5 transponders to the side of that optical transponder; the first optical switches
12a to 12c that selectively output the optical signal received from the optical
fiber lines or the optical signal looped back by the local optical loopback
circuit to the optical transponders by an external switching operation; the
second optical switches 12d to 12f that selectively output the optical signal
10 received from the optical transponders to one system of the optical fiber lines
or the local optical loopback circuit by an external switching operation; and
the module inspection unit 40 that operates in accordance with an external
operational instruction. The method includes: controlling switching of the
first optical switches so as to output the optical signal looped back by the
15 local optical loopback circuit to the optical transponders (step S201 in Fig. 2);
at the same time, controlling switching of the second optical switches so as to
output the optical signal received from the optical transponders to the local
optical loopback circuit (step S202 in Fig. 2); then causing the optical
transponders to operate and emit the optical signal (step S203 in Fig. 2); and
20 determining whether the optical transponders have received the optical signal
looped back by the local optical loopback circuit (step S204 in Fig. 2).
[0046] The above-described operational steps may be provided in a
computer-executable program, so that the program can be executed by the
processor 41 in the module inspection unit 40, which directly executes the
25 above-described steps. The program may be recorded in a non-transitory
recording medium, such as a DVD, a CD, and a flash memory. In this case,
the program is read from the recording medium and executed by the computer.
Through this operation, the present exemplary embodiment has the
following advantageous effects.
[0047] In the present exemplary embodiment, when a failure occurs in the
wavelength multiplexer, whether the failed portion is before or after the
split-and-select module can be surely and easily be identified. None of the
cumbersome operation such as the manual disconnection/connection of an
5 optical cable and transmission system switching, nor a special measurement
device is required in the process. All it requires is to issue a simple
instruction to execute an inspection to the module inspection unit 40, and the
module inspection unit 40 will execute the inspection.
[0048] The module inspection unit 40 may necessarily be in direct connection
10 with the wavelength multiplexer 100, and may remotely operate the
wavelength multiplexer 100 through a network and the like. When
maintenance can be performed through the remote operation, the labor and
cost required for the maintenance can be largely reduced.
[0049] The local optical loopback circuit may not necessarily be provided for
15 each system of the transponders 21 to 23. A single system of the local
optical Ioopback circuit in the wavelength multiplexer 100 as a whole may be
shared among all the systems. This configuration can largely reduce the cost
for the multiplexer, and contribute to downsizing and cost reduction.
[0050] (Second exempla*Jyem bodiment)
20 A wavelength multiplexer 300 according to a second exemplary
embodiment of the present invention includes, in addition to the configuration
described in the first exemplary embodiment, a remote optical loopback
circuit 3 14 that loops back and outputs an optical signal input from any of the
optical fiber line to the side of that optical fiber line. In addition, the optical
25 switches l l a to I l c selectively output the optical signal received from the
optical fiber lines or the optical signal looped back by the local optical
loopback circuit to the optical transponders or the remote optical loopback
circuit by an external switching operation. The second optical switches 1 ld
to l l f selectively output the optical signal received from the optical
transponders or the remote optical loopback circuit to any one system of the
plurality of systems of the optical fiber lines or the local optical loopback
circuit by an external switching operation.
[0051] As well as providing the same advantageous effects as in the first
5 exemplary embodiment, this configuration can detect an abnormality in an
apparatus on the other side connected to the wavelength multiplexer 300
through the optical fiber line. In this case, there is no need to change the
configuration of the apparatus on the other side.
The following describes this configuration in greater detail.
10 [0052] Fig. 3 is a diagram illustrating the configuration of the wavelength
multiplexer 300 according to the second exemplary embodiment of the present
invention. Since the wavelength multiplexer 300 mainly includes the same
configuration as that of the wavelength multiplexer 100 according to the first
exemplary embodiment described above, like elements are denoted with like
15 names and reference signs, and these descriptions will be omitted.
[0053] A split-and-select module 3 10 included in the wavelength multiplexer
300 further includes, in addition to the configuration described in the first
exemplary embodiment, two optical switches 312g and 312h. The optical
signals output from the optical switches 312g are directly input to the optical
20 switches 312h. Thus, the optical switches 312g and 312h are also
collectively referred to as a remote optical loopback circuit 3 14.
[0054] For example, whether the WDM route 101 after the split-and-select
module 310 is appropriately connected can be checked by using above remote
optical loopback circuit as follows. Specifically, the optical switch 312g
25 performs switching so that the optical signal output from the optical coupler
l l a is output to the optical switch 312h. Then, the optical switch 312h
performs switching so that the optical signal is output to the optical coupler
l l d .
[0055] Thus, if the WDM route 101 after the split-and-select module 3 10 is
under failure, the abnormality can be detected in an apparatus on the other
side connected to the wavelength multiplexer 300 through the WDM route 101.
Thus, it is apparent that the WDM route 101 has the abnormality. The other
WDM routes 102 and 103 can be checked in a similar manner to see whether
5 there is an abnormality. Here, the apparatus on the other side may not have a
configuration similar to that in the present embodiment.
[0056] The present invention has been described with reference to specific
exemplary embodiments illustrated in the accompanying drawings, but the
present invention is not limited to the exemplary embodiments illustrated in
10 the drawings. Any known configuration can be adopted as long as it
provides the advantageous effects of the present invention.
[0057] The following describes the overview of the novel technical features
of the above-described exemplary embodiments. While the exemplary
embodiments can be partially or entirely summarized as a novel technique as
15 described below, the present invention is not necessarily limited to this.
[0058] (Supplementary Note 1) A wavelength multiplexer connected with and
provided between a plurality of systems or a single system of optical fiber
lines and a plurality of systems or a single system of optical transponders, and
inputting and outputting an optical signal to and from the optical fiber lines
20 and the optical transponders, the wavelength multiplexer including:
first optical switches that output an optical signal input from the
optical fiber lines to the optical transponders;
second optical switches that output an optical signal input from the
optical transponders to the optical fiber lines; and
2 5 a local optical loopback circuit that loops back and outputs an optical
signal input from any of the optical transponders to the side of that optical
transponder.
[0059] (Supplementary Note 2) The wavelength multiplexer according to
Supplementary Note 1, in which the first optical switches have a function of
selectively outputting the optical signal received from the optical fiber lines
or the optical signal looped back by the local optical loopback circuit to the
optical transponders by an external switching operation, and
the second optical switches have a function of selectively outputting
5 the optical signal received from the optical transponders to one system of the
optical fiber lines or the local optical loopback circuit by an external
switching operation.
[0060] (Supplementary Note 3) The wavelength multiplexer according to
Supplementary Note 2, further including: first optical couplers that each
10 branch an optical signal received from a corresponding one of the optical fiber
lines and output the resultant signal to each first optical switch; and
second optical couplers that each multiplex an optical signal received
from a corresponding one of the second optical switches and output the
resultant signal to each optical fiber line.
15 [0061] (Supplementary Note 4) The wavelength multiplexer according to
Supplementary Note 2, further including a module inspection unit that
operates in accordance with an external operational instruction, in which
the module inspection unit has a function of controlling switching of
the first optical switches so as to output the optical signal looped back by the
20 local optical loopback circuit to the optical transponders,
the module inspection unit has a function of, at the same time,
controlling switching of the second optical switches so as to output the optical
signal received from the optical transponders to the local optical loopback
circuit, and
2 5 the module inspection unit has a function of then causing the optical
transponders to emit the optical signal and determining whether the optical
transponders have received the optical signal looped back by the local optical
loopback circuit.
[0062] (Supplementary Note 5) The wavelength multiplexer according to
Supplementary Note 2, further including a remote optical loopback circuit that
loops back and outputs an optical signal input from any of the optical fiber
lines to the side of that optical fiber line, in which
the first optical switches have a function of selectively outputting the
5 optical signal received from the optical fiber lines or the optical signal looped
back by the local optical loopback circuit to the optical transponders or the
remote optical loopback circuit by an external switching operation, and
the second optical switches have a function of selectively outputting
the optical signal received from the optical transponders or the remote optical
10 loopback circuit to any one system of the optical fiber lines or the local
optical loopback circuit by an external switching operation.
[0063] (Supplementary Note 6) A method for identifying a failed portion
executed by a module inspection unit included in a split-and-select module
included in a wavelength multiplexer, the split-and-select module being
15 connected with a plurality of systems of optical fiber lines and optical
transponders, and inputting and outputting an optical signal to and from the
optical fiber lines and the optical transponders,
the split-and-select module including: a local optical loopback circuit
that loops back and outputs an optical signal input from any of the optical
20 transponders to the side of that optical transponder; first optical switches that
selectively output the optical signal received from the optical fiber lines or the
optical signal looped back by the local optical loopback circuit to the optical
transponders by an external switching operation; second optical switches that
selectively output the optical signal received from the optical transponders to
25 one system of the optical fiber lines or the local optical loopback circuit by an
external switching operation; and the module inspection unit that operates in
accordance with an external operational instruction, the method including:
controlling switching of the first optical switches so as to output the
optical signal looped back by the local optical loopback circuit to the optical
transponders;
at the same time, controlling switching of the second optical switches
so as to output the optical signal received from the optical transponders to the
local optical loopback circuit; and
5 then causing the optical transponders to operate and emit the optical
signal and determining whether the optical transponders have received the
optical signal looped back by the local optical loopback circuit.
[0064] (Supplementary Note 7) A program for identifying a failed portion
containing processes executed by a processor included in a module inspection
10 unit included in a split-and-select module included in a wavelength
multiplexer, the split-and-select module being connected with a plurality of
systems of optical fiber lines and optical transponders, and inputting and
outputting an optical signal to and from the optical fiber lines and the optical
transponders,
15 the split-and-select module including: a local optical loopback circuit
that loops back and outputs an optical signal input from any .of the optical
transponders to the side of that optical transponder; first optical switches that
selectively output the optical signal received from the optical fiber lines or the
optical signal looped back by the local optical loopback circuit to the optical
20 transponders by an external switching operation; second optical switches that
selectively output the optical signal received from the optical transponders to
one system of the optical fiber lines or the local optical loopback circuit by an
external switching operation; and the module inspection unit that operates in
accordance with an external operational instruction,
25 the processes including:
switching of the first optical switches so as to output the
optical signal looped back by the local optical loopback circuit to the optical
transponders;
at the same time, switching of the second optical switches so
as to output the optical signal received from the optical transponders to the
local optical loopback circuit; and
then causing the optical transponders to operate and emit the
optical signal and determining whether the optical transponders have received
5 the optical signal looped back by the local optical loopback circuit.
[0065] The present application claims priority based on Japanese Patent
Application No. 2012-1 69440 filed on July 3 1, 2012, the entirety of which is
incorporated herein by reference.
[Industrial Applicability]
10 [0066] The present invention is suitably applied to wavelength multiplexers,
and more particularly to a reconfigurable optical addldrop multiplexer
(ROADM).
[Reference signs List]
[0067] 10, 3 10 split-and-select module
15 11 a to 11 h optical coupler
12a to 12f, 3 12g to 3 12h optical switch
13 local optical loopback circuit
2 1, 22, 23 transponder
40 module inspection unit
2 0 41 processor
42 input and output means
43 inspection means
100, 300 wavelength multiplexer
101, 102, 103 WDM route
25 10 1 a, 102a, 103a splitter
101 b, 102b, 103b multiplexer
3 14 remote optical loopback circuit

WE CLAIMS:-
A wavelength multiplexer connected with and provided
between a plurality of systems or a single system of optical fiber lines and a
plurality of systems or a single system of optical transponders, and inputting
5 and outputting an optical signal to and from the optical fiber lines and the'
optical transponders, the wavelength multiplexer comprising:
a first optical switch that outputs an optical signal input from the
optical fiber lines to the optical transponders;
a second optical switch that outputs an optical signal input from the
10 optical transponders to the optical fiber lines; and
a local optical loopback circuit that loops back and outputs an optical
signal input from any of the optical transponders to the side of that optical
transponder.
15 [Claim 21 The wavelength multiplexer according to claim 1, wherein
the first optical switch has a function of selectively outputting the
optical signal received from the optical fiber lines or the optical signal looped
back by the local optical loopback circuit to the optical transponders by an
external switching operation, and
20 the second optical switch has a function of selectively outputting the
optical signal received from the optical transponders to one system of the
optical fiber lines or the local optical loopback circuit by an external
switching operation.
25 [Claim 31 The wavelength multiplexer according to claim 2, further
comprising:
first optical couplers that 'each branch an optical signal received from
a corresponding one of the optical fiber lines and output the resultant signal to
each first optical switch; and
second optical couplers that each multiplex an optical signal received
from a corresponding one of the second optical switch and output the resultant
signal to each optical fiber line.
5 [Claim 41 The wavelength multiplexer according to claim 2, further
including a module inspection unit that operates in accordance with an
external operational instruction, wherein
the module inspection unit has a function of controlling switching of
the first optical switch so as to output the optical signal looped back by the
10 local optical loopback circuit to the optical transponders,
.the module inspection unit has a function of, at the same time,
controlling switching of the second optical switch so as to output the optical
signal received from the optical transponders to the local optical loopback
circuit, and
15 the module inspection unit has a function of then causing the optical
transponders to emit the optical signal and determining whether the optical
transponders have received the optical signal looped back by the local optical
loopback circuit.
20 [Claim 51 The wavelength multiplexer according to claim 2, further
comprising a remote optical loopback circuit that loops back and outputs an
optical signal input from any of the optical fiber lines to the side of that
optical fiber line, wherein
the first optical switch has a function of selectively outputting the
25 optical signal received from the optical fiber lines or the optical signal looped
back by the local optical loopback circuit to the optical transponders or the
remote optical loopback circuit by an external switching operation, and
the second optical switch has a function of selectively outputting the
optical signal received from the optical transponders or the remote optical
loopback circuit to any one system of the optical fiber lines or the local
optical loopback circuit by an external switching operation.
[Claim 61 A method for identifying a failed portion executed by a module
5 inspection unit included in a split-and-select module included in a wavelength
multiplexer, the split-and-select module being connected with a plurality of
systems of optical fiber lines and optical transponders and inputting and
outputting an optical signal to and from the optical fiber lines and the optical
transponders,
10 the split-and-select module comprising: a local optical loopback *
circuit that loops back and outputs an optical signal input from any of the
optical transponders to the side of that optical transponder; first optical
switches that selectively output the optical signal received from the optical
fiber lines or the optical signal looped back by the local optical loopback
15 circuit to the optical transponders by an external switching operation; second
optical switches that selectively output the optical signal received from the
optical transponders to one system of the optical fiber lines or the local
optical loopback circuit by an external switching operation; and the module
inspection unit that operates in accordance with an external operational
20 instruction, the method comprising:
controlling switching of the first optical switches so as to output the
optical signal looped back by the local optical loopback circuit to the optical
transponders;
at the same time, controlling switching of the second optical switches
25 so as to output the optical signal received from the optical transponders to the
local optical loopback circuit; and
then causing the optical transponders to operate and emit the optical
signal and determining whether the optical transponders have received the
optical signal looped back by the local optical loopback circuit.
[Claim 71 A program for identifying a failed portion containing
processes executed by a processor included in a module inspection unit
included in a split-and-select module included in a wavelength multiplexer,
5 the split-and-select module being connected with a plurality of systems of
optical fiber lines and optical transponders and inputting and outputting an
optical signal to and from the optical fiber lines and the optical transponders,
the split-and-select module comprising: a local optical loopback
circuit that loops back and outputs an optical signal input from any of the
10 optical transponders to the side of that optical transponder; first optical
switches that selectively output the optical signal received from the optical
,&
1 < ' ,
fi,ber lines or the optical signal looped back by the local optical I l,o opback
circuit to the optical tr,ansponders by an external switching operIa tionI ;, s, econd
optical switches that selectively output the optical sig, na, l\ ,received I ) from the
15 optical transponders to one system of the optical fiber lines or the local
optical loopbqck circuit by an external switching operation; I s and the module
inspection unit that operates in accordance with an external operational
instruction,
the processes comprising:
20 switching of the first o p t i ~ a l switches so as to output, thq:
optical signal looped back by the local. optical loopback circuit to the optical
transponders;
, at the same time, switching of the secon
as to output the optical signal received from the optical t~ansponders to the
25 local optical loopback circuit; and ! I ,
then causing the optical transponders to operate and emit the
optical signal and determining whether the optical transponders have received
the optical signal looped back by the local optical loopback circuit.