U.S. patent application number 15/712214 was filed with the patent office on 2019-03-28 for optical time-domain reflectometer interoperable trunk switch.
The applicant listed for this patent is Ciena Corporation. Invention is credited to Jean-Luc ARCHAMBAULT, Paul CHEDORE.
Application Number | 20190097719 15/712214 |
Document ID | / |
Family ID | 65808063 |
Filed Date | 2019-03-28 |
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United States Patent
Application |
20190097719 |
Kind Code |
A1 |
CHEDORE; Paul ; et
al. |
March 28, 2019 |
OPTICAL TIME-DOMAIN REFLECTOMETER INTEROPERABLE TRUNK SWITCH
Abstract
An optical trunk switch supporting an Optical Time-Domain
Reflectometer (OTDR) includes a transmit switch configured to
provide an input signal to one or more of a primary fiber path and
a standby fiber path; a receive switch configured to provide an
output signal from one of the primary fiber path and the standby
fiber path; and an OTDR connection configured to provide one or
more OTDR signals to monitor an inactive path of the primary fiber
path and the standby fiber.
Inventors: |
CHEDORE; Paul; (Ottawa,
CA) ; ARCHAMBAULT; Jean-Luc; (Ottawa, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ciena Corporation |
Hanover |
MD |
US |
|
|
Family ID: |
65808063 |
Appl. No.: |
15/712214 |
Filed: |
September 22, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04Q 11/0062 20130101;
H04Q 11/0005 20130101; H04Q 11/00 20130101; G01M 11/3109 20130101;
H04Q 2011/0083 20130101; H04Q 11/0001 20130101; H04B 10/071
20130101; H04Q 2011/0015 20130101 |
International
Class: |
H04B 10/071 20060101
H04B010/071; H04Q 11/00 20060101 H04Q011/00 |
Claims
1. An optical trunk switch supporting an Optical Time-Domain
Reflectometer (OTDR), the optical trunk switch comprising: a
transmit switch configured to provide an input signal to one or
more of a primary fiber path and a standby fiber path; a receive
switch configured to provide an output signal from one of the
primary fiber path and the standby fiber path; and an integrated
OTDR system in a same housing as the transmit switch and the
receive switch, wherein the integrated OTDR system has an OTDR
connection to one or more of the transmit switch and the receive
switch, wherein the integrated OTDR system is configured to provide
one or more OTDR signals to monitor an inactive path of the primary
fiber path and the standby fiber, based on configuration of the
transmit switch and the receive switch.
2. The optical trunk switch of claim 1, wherein the transmit switch
and the receive switch each comprise a 2.times.2 switch.
3. The optical trunk switch of claim 2, wherein the integrated OTDR
system is connected separately to each of the transmit switch and
the receive switch to provide a co-propagating OTDR signal on the
inactive path in a transmit direction and a counter-propagating
OTDR signal on the inactive path in a receive direction.
4. (canceled)
5. (canceled)
6. The optical trunk switch of claim 1, wherein the one or more
OTDR signals comprise a co-propagating OTDR signal to monitor a
transmit direction of the inactive path and a counter-propagating
OTDR signal to monitor a receive direction of the inactive
path.
7. (canceled)
8. (canceled)
9. (canceled)
10. An optical trunk switch supporting an Optical Time-Domain
Reflectometer (OTDR), the optical trunk switch comprising: a
transmit 2.times.2 switch configured to provide an input signal to
an active path and to provide a co-propagating OTDR signal to an
inactive path; a receive 2.times.2 switch configured to provide an
output signal from the active path and to provide a
counter-propagating OTDR signal to the inactive path; and an
integrated OTDR system in a same housing as the transmit switch and
the receive switch, wherein the integrated OTDR system has an OTDR
connection to the transmit 2.times.2 switch and the receive
2.times.2 switch, wherein the integrated OTDR system is configured
to provide the co-propagating OTDR signal and the
counter-propagating OTDR signal, based on configuration of the
transmit 2.times.2 switch and the receive 2.times.2 switch.
11. The optical trunk switch of claim 10, wherein the OTDR
connection is integrated OTDR system connected separately to each
of the transmit switch and the receive switch to provide the
co-propagating OTDR signal on the inactive path in a transmit
direction and the counter-propagating OTDR signal on the inactive
path in a receive direction.
12. (canceled)
13. (canceled)
14. (canceled)
15. (canceled)
16. A method for providing an optical trunk switch supporting an
Optical Time-Domain Reflectometer (OTDR), the method comprising:
providing a transmit switch configured to provide an input signal
to one or more of a primary fiber path and a standby fiber path;
providing a receive switch configured to provide an output signal
from one of the primary fiber path and the standby fiber path; and
providing an integrated OTDR system in a same housing as the
transmit switch and the receive switch, wherein the integrated OTDR
system has an OTDR connection to one or more of the transmit switch
and the receive switch, wherein the integrated OTDR system is
configured to provide one or more OTDR signals to monitor an
inactive path of the primary fiber path and the standby fiber,
based on configuration of the transmit switch and the receive
switch.
17. The method of claim 16, wherein the transmit switch and the
receive switch each comprise a 2.times.2 switch.
18. (canceled)
19. (canceled)
20. The method of claim 16, wherein the one or more OTDR signals
comprise a co-propagating OTDR signal to monitor a transmit
direction of the inactive path and a counter-propagating OTDR
signal to monitor a receive direction of the inactive path.
21. The method of claim 16, wherein the OTDR connection includes
one or more combiners configured to add the one or more OTDR
signals to an active path of the primary fiber path and the standby
fiber.
22. The method of claim 16, wherein the transmit switch and the
receive switch each comprise a 2.times.2 switch with a first input
including a signal and a combiner which adds the one or more OTDR
signals to the signal for an active path of the primary fiber path
and the standby fiber, and a second input which directly adds the
one or more OTDR signals to the inactive path.
23. The optical trunk switch of claim 1, wherein the OTDR
connection includes one or more combiners configured to add the one
or more OTDR signals to an active path of the primary fiber path
and the standby fiber.
24. The optical trunk switch of claim 1, wherein the transmit
switch and the receive switch each comprise a 2.times.2 switch with
a first input including a signal and a combiner which adds the one
or more OTDR signals to the signal for an active path of the
primary fiber path and the standby fiber, and a second input which
directly adds the one or more OTDR signals to the inactive
path.
25. The optical trunk switch of claim 10, wherein the OTDR
connection includes one or more combiners configured to add the one
or more OTDR signals to an active path of the primary fiber path
and the standby fiber.
26. The optical trunk switch of claim 1, wherein the transmit
2.times.2 switch and the receive 2.times.2 switch each comprise a a
first input including a signal and a combiner which an OTDR signal
to the signal for an active path of the primary fiber path and the
standby fiber, and a second input which directly adds the OTDR
signal to the inactive path.
Description
FIELD OF THE DISCLOSURE
[0001] The present disclosure generally relates to optical
networking systems and methods. More particularly, the present
disclosure relates to an Optical Time-Domain Reflectometer (OTDR)
Interoperable Trunk Switch.
BACKGROUND OF THE DISCLOSURE
[0002] Optical trunk switches (also referred to as Optical
Protection Switches (OPSs), optical switches, etc.), are
all-optical devices that enable a single client (0:1) to support
line-side protection (1+1, 1:1, optical ring protection, etc.).
Specifically, an optical trunk switch can take a single optical
channel (TX/RX) and provide it on two redundant fiber paths. These
devices are designed to automatically detect traffic interruptions
and quickly reroute/switch traffic from a primary fiber path to a
standby fiber path. Optical trunk switches can be deployed in
various scenarios, such as metro networks, Data Center
interconnects, etc. Advantageously, optical switches are used to
reduce client interfaces since a vast majority of faults are on the
line side such as in the optical network affecting one of the
lines. That is, fiber cuts or other failures in the optical network
are more common than equipment failures, thus optical trunk
switches provide a cost-effective approach to offer redundancy.
[0003] Also, Optical Time-Domain Reflectometer (OTDR) is a feature
that is increasingly becoming commonplace in network deployments,
such as integrated OTDR systems in an optical line system, i.e.,
integrated into modems, amplifiers, multiplexers, Reconfigurable
Optical Add-Drop Multiplexers (ROADMs), etc. An OTDR provides
detailed distance referenced characterization of the physical fiber
plant. The OTDR generally operates by sending optical test signals
into the fiber and detecting, at the same end, the scattered
(Rayleigh backscatter) or reflected back light from points along
the fiber. This information helps operators monitor and detect
fiber span related issues, e.g., bad or poor slices, high
attenuation, physical defects, etc.
[0004] At present, there is an incompatibility between optical
trunk switches and OTDR based on the structure of conventional
optical trunk switches. Specifically, optical trunk switches
typically broadcast a transmit signal on both the primary and
standby fiber and switch a received signal from only one of the
primary and standby fiber. Thus, there is no conventional approach
to use OTDR with an optical trunk switch to monitor both the
primary and standby fibers while in-service. That is, the
conventional optical trunk switch would send an OTDR test signal
over both the primary and standby fibers in the transmit direction
and only receive the OTDR test signal in the receive direction
based on which fiber is currently active.
BRIEF SUMMARY OF THE DISCLOSURE
[0005] In an embodiment, an optical trunk switch supporting an
Optical Time-Domain Reflectometer (OTDR) includes a transmit switch
configured to provide an input signal to one or more of a primary
fiber path and a standby fiber path; a receive switch configured to
provide an output signal from one of the primary fiber path and the
standby fiber path; and an OTDR connection configured to provide
one or more OTDR signals to monitor an inactive path of the primary
fiber path and the standby fiber. The transmit switch and the
receive switch each can include a 2.times.2 switch. The OTDR
connection can be connected separately to each of the transmit
switch and the receive switch to provide a co-propagating OTDR
signal on the inactive path in a transmit direction and a
counter-propagating OTDR signal on the inactive path in a receive
direction. The OTDR connection can include an OTDR port connected
to an external module which supports the one or more OTDR signals
to monitor the inactive path. The OTDR connection can include an
integrated OTDR system in the optical trunk switch. The one or more
OTDR signals can include a co-propagating OTDR signal to monitor a
transmit direction of the inactive path and a counter-propagating
OTDR signal to monitor a receive direction of the inactive path.
The optical trunk switch can include a splitter connected to the
OTDR connection and configured to split the co-propagating OTDR
signal and the counter-propagating OTDR signal to a respective one
of the transmit switch and the receive switch. The transmit switch
can include a 1.times.2 splitter and the receive switch can include
a 2.times.2 switch, and wherein the OTDR connection is connected to
the 2.times.2 switch to provide a counter-propagating OTDR signal
to monitor a receive direction of the inactive path. The OTDR
connection can receive an OTDR signal and connect to a 1.times.2
switch which is configured to selectively provide the OTDR signal
as one of a co-propagating OTDR signal in a transmit direction on
the inactive path and a counter-propagating OTDR signal in a
receive direction on the inactive path.
[0006] In another embodiment, an optical trunk switch supporting an
Optical Time-Domain Reflectometer (OTDR) includes a transmit
2.times.2 switch configured to provide an input signal to an active
path and to provide a co-propagating OTDR signal to an inactive
path; a receive 2.times.2 switch configured to provide an output
signal from the active path and to provide a counter-propagating
OTDR signal to the inactive path; and an OTDR connection for the
co-propagating OTDR signal and the counter-propagating OTDR signal.
The OTDR connection can be connected separately to each of the
transmit switch and the receive switch to provide the
co-propagating OTDR signal on the inactive path in a transmit
direction and the counter-propagating OTDR signal on the inactive
path in a receive direction. The OTDR connection can include an
OTDR port connected to an external module which supports the
co-propagating OTDR signal and the counter-propagating OTDR signal
to monitor the inactive path. The OTDR connection can include an
integrated OTDR system in the optical trunk switch. The optical
trunk switch can include a splitter connected to the OTDR
connection and configured to split the co-propagating OTDR signal
and the counter-propagating OTDR signal to a respective one of the
transmit 2.times.2 switch and the receive 2.times.2 switch. The
OTDR connection can receive an OTDR signal and connect to a
1.times.2 switch which is configured to selectively provide the
OTDR signal as one of the co-propagating OTDR signal in a transmit
direction on the inactive path and the counter-propagating OTDR
signal in a receive direction on the inactive path.
[0007] In a further exemplary embodiment, a method for providing an
optical trunk switch supporting an Optical Time-Domain
Reflectometer (OTDR) includes providing a transmit switch
configured to provide an input signal to one or more of a primary
fiber path and a standby fiber path; providing a receive switch
configured to provide an output signal from one of the primary
fiber path and the standby fiber path; and providing an OTDR
connection configured to provide one or more OTDR signals to
monitor an inactive path of the primary fiber path and the standby
fiber. The transmit switch and the receive switch each can include
a 2.times.2 switch. The OTDR connection can include an OTDR port
connected to an external module which supports the one or more OTDR
signals to monitor the inactive path. The OTDR connection can
include an integrated OTDR system in the optical trunk switch. The
one or more OTDR signals can include a co-propagating OTDR signal
to monitor a transmit direction of the inactive path and a
counter-propagating OTDR signal to monitor a receive direction of
the inactive path.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The present disclosure is illustrated and described herein
with reference to the various drawings, in which like reference
numbers are used to denote like system components/method steps, as
appropriate, and in which:
[0009] FIG. 1 is a block diagram of a conventional optical trunk
switch using a splitter in the transmit direction and a 1.times.2
switch in the receive direction;
[0010] FIG. 2 is a block diagram of a conventional optical trunk
switch using 1.times.2 switches in both the transmit direction and
the receive direction;
[0011] FIG. 3 is a block diagram of a convention optical trunk
switch using a 2.times.2 switch in the transmit direction and a
1.times.2 switch in the receive direction;
[0012] FIG. 4 is a block diagram of an OTDR interoperable trunk
switch using a 2.times.2 switch in both the transmit direction and
the receive direction and with an OTDR port enabling OTDR signals
over both the primary fiber path and the and standby fiber path
regardless of which is currently set as the active fiber path;
[0013] FIG. 5 is a block diagram of the OTDR interoperable trunk
switch with the 2.times.2 switches switched from the configuration
of FIG. 4;
[0014] FIG. 6 is a block diagram of an OTDR interoperable trunk
switch with an OTDR port which provides separate inputs for the
OTDR signals;
[0015] FIG. 7 is a block diagram of an OTDR interoperable trunk
switch with an OTDR port supporting a single wavelength
counter-propagating OTDR signal for unidirectional OTDR
monitoring;
[0016] FIG. 8 is a block diagram of an OTDR interoperable trunk
switch with an OTDR port supporting a single wavelength
counter-propagating OTDR signal along with a 1.times.2 switch for
bidirectional OTDR monitoring;
[0017] FIG. 9 is a block diagram of an OTDR interoperable trunk
switch with an integrated OTDR system;
[0018] FIGS. 10-14 are network diagrams of OTDR interoperable trunk
switches interconnected by the primary fiber path and the standby
fiber path illustrating a sequence of events based on a fiber cut;
and
[0019] FIG. 15 is a block diagram of an OTDR module interconnected
to the OTDR interoperable trunk switch.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0020] In various embodiments, the present disclosure relates to an
Optical Time-Domain Reflectometer (OTDR) Interoperable Trunk
Switch. The OTDR interoperable trunk switch supports unidirectional
or bidirectional OTDR monitoring of both the primary and standby
fiber paths in-service. Generally, the OTDR interoperable trunk
switch includes one or more additional optical ports to support the
inclusion of OTDR test signals for monitoring an inactive fiber
path. Advantageously, the OTDR interoperable trunk switch enables
operators to monitor both active and inactive fiber paths extending
OTDR support to optical trunk switches. Various embodiments are
described which support dual or single wavelength (WL) OTDR signals
as well as unidirectional and bidirectional monitoring. The
unidirectional monitoring supports one fiber direction (e.g.,
counter-propagating in the receive direction). The bidirectional
monitoring supports both fiber directions (i.e., co-propagating in
the transmit direction and counter-propagating in the receive
direction). The dual wavelength OTDR signals enable the additional
optical port to receive both co-propagating and counter-propagating
signals on the same fiber with an integrated splitter configured to
split the separate wavelengths.
Conventional Optical Trunk Switch
[0021] FIG. 1 is a block diagram of a conventional optical trunk
switch 10A using a splitter 12 in the transmit direction and a
1.times.2 switch 14 in the receive direction. In operation, the
splitter 12 is configured to receive an input signal 16 in the
transmit direction and split the same input signal to both a
primary fiber path 18 and a standby fiber path 20. The 1.times.2
switch 14 is configured to receive an output signal 22 from both
the primary fiber path 18 and the standby fiber path 20 and to
provide only the output signal 22 from an active fiber based on the
1.times.2 switch 14 setting. For example, the optical trunk switch
10A can include detectors 24 which are used to set the 1.times.2
switch 14. The detectors 24 can also provide monitoring of the
signals from the splitter 12. The output signal 22 can include the
input signal 16 from an adjacent optical trunk switch 10A (i.e.,
remote node) which has been provided to both the fiber paths 18,
20.
[0022] OTDR signals are incompatible with the optical trunk switch
10A. A co-propagating OTDR signal 26 travels both paths based on
the splitter 12, and thus it is impossible to resolve to which path
(i.e., which fiber path 18, 20) a reflection event belongs. A
counter-propagating OTDR signal 28 would only monitor the active
path based on the setting of the 1.times.2 switch 14.
[0023] FIG. 2 is a block diagram of a conventional optical trunk
switch 10B using 1.times.2 switches 14 in both the transmit
direction and the receive direction. The optical trunk switch 10B
operates in a similar manner as the optical trunk switch 10A in the
receive direction. However, the splitter 12 is replaced with a
1.times.2 switch 14 which directs the input signal 16 based on the
setting of the 1.times.2 switch 14, i.e., the transmit direction
only sends one copy of the input signal 16 on the active fiber of
the fiber path 18, 20. Here, the OTDR signals 26, 28 can monitor a
path since only one copy is sent in the transmit direction.
However, the optical trunk switch 10B can only support OTDR
monitoring in the active path.
[0024] FIG. 3 is a block diagram of a conventional optical trunk
switch 10C using a 2.times.2 switch 30 in the transmit direction
and a 1.times.2 switch 14 in the receive direction. The optical
trunk switch 10C operates in a similar manner as the optical trunk
switches 10A, 10B in the receive direction. However, the transmit
direction includes the 2.times.2 switch 30 which is configured to
provide the input signal 16 to the active fiber based on the
settings of the 2.times.2 switch 30. Additionally, the 2.times.2
switch 30 has a second input 32 which is sent to the inactive fiber
based on the settings of the 2.times.2 switch 30. For example, the
second input 32 can be connected to a pilot tone which simply
provides a connectivity verification at an adjacent optical trunk
switch 10C. The pilot tone can simply be a signal at a specified
wavelength or Amplified Stimulated Emission (ASE). The optical
trunk switch 10C has the same issues related to OTDR as the optical
trunk switch 10B, here again, the co-propagating and
counter-propagating OTDR signals 26, 28 would only monitor the
active path.
OTDR Interoperable Trunk Switch--Dual Wavelength (WL) and
Bidirectional
[0025] FIG. 4 is a block diagram of an OTDR interoperable trunk
switch 100 using 2.times.2 switches 30A, 30B in both the transmit
direction and the receive direction and with an OTDR port 102
enabling OTDR signals over both the primary fiber path 18 and the
standby fiber path 20 regardless of which is currently set as the
active fiber path. Specifically, the OTDR interoperable trunk
switch 100 uses dual wavelengths for the OTDR signals 26, 28, 26A,
28A and supports bidirectional OTDR monitoring of both fiber paths
18, 20.
[0026] The OTDR interoperable trunk switch 100 can include a
housing 104 with three client-side ports 102, 106, 108 and four
line-side ports 110, 112, 114, 116. The client-side port 106 is
configured to receive the input signal 16 along with the
co-propagating OTDR signal 26 and connects to an input port of the
2.times.2 optical switch 30A. The co-propagating OTDR signal 26 is
configured to provide OTDR monitoring in the transmit direction on
the active fiber (pair). As described herein, the physical fibers
include the primary fiber path 18 and the standby fiber path 20.
These fiber paths 18, 20 can further be categorized as active and
inactive, and either can be active or inactive based on the
settings of the 2.times.2 optical switches 30A, 30B.
[0027] The client-side port 108 is configured to receive the output
signal 22 from the 2.times.2 optical switch 30B in the receive
direction and to provide the counter-propagating OTDR signal 28 to
the optical switch 30B. The counter-propagating OTDR signal 28 is
configured to provide OTDR monitoring in the receive direction on
the active fiber (pair). Thus, from an OTDR perspective, the OTDR
interoperable trunk switch 100 operates in a similar manner as the
OTDR interoperable trunk switches 10B, 10C in terms of monitoring
the active fiber (pair).
[0028] Additionally, the OTDR interoperable trunk switch 100
includes the OTDR port 102 to receive OTDR signals 26A, 28A for
monitoring the inactive fiber path which is the standby fiber path
20. In this example, the OTDR port 102 is shown as a single port
carrying both the OTDR signals 26A, 28A at different wavelengths.
The OTDR interoperable trunk switch 100 can include for example a
red/blue splitter 120 which splits the OTDR signals 26A, 28A
between the transmit direction and the receive direction. The
red/blue splitter 120 is configured to send the OTDR signal 26A to
the 2.times.2 optical switch 30A and the OTDR signal 28A to the
2.times.2 optical switch 30B. The 2.times.2 optical switches 30A,
30B enable the inactive fiber path which is the standby fiber path
20 to receive the OTDR signals 26A, 28A thus enabling OTDR
monitoring of the inactive fiber path which is the standby fiber
path 20. Note, the OTDR port 102 can be two separate ports each
connected to a respective 2.times.2 optical switch 30A, 30B without
requiring the red/blue splitter 120.
[0029] The 2.times.2 switches 30A, 30B are a cross-bar switch which
receives two inputs and can provide each of the two inputs to
either output based on the current settings. In FIG. 4, the
2.times.2 switches 30A, 30B are shown with the top input connected
to the top output and the bottom input connected to the bottom
output. Thus, the client-side port 106 is connected to the
line-side port 110 which connects to the primary fiber path 18 in
the transmit direction. The client-side port 108 is connected to
the line-side port 116 which connects to the primary fiber path 18
in the receive direction. The standby fiber path 20 is inactive in
this example, and the line-side port 112 is connected to the OTDR
port 102 receiving the co-propagating OTDR signal 26A. The
line-side port 114 is connected to the OTDR port 102 receiving the
counter-propagating OTDR signal 28A. Thus, the OTDR signals 26A,
28A can monitor the standby fiber path 20 which is inactive. In a
switch scenario where the standby fiber path 20 becomes active, the
2.times.2 switches 30A, 30B would switch the top ports to the
bottom ports.
[0030] The use of 2.times.2 cross-bar switches at both the near and
far end allows both co-propagating and/or counter-propagating OTDR
signals 26, 28, 26A, 28A to be injected into the active and standby
fiber plant simultaneously. This capability allows the OTDR signals
26, 28, 26A, 28A to monitor the standby fiber path and also to
validate a repair before declaring a damaged fiber path usable
again.
[0031] FIG. 5 is a block diagram of the OTDR interoperable trunk
switch 100 with the 2.times.2 switches 30A, 30B switched from the
configuration of FIG. 4. Again, in FIG. 4, the OTDR signals 26, 28
provide OTDR monitoring of the active fiber path which is the
primary fiber path 18. The OTDR signals 26A, 28A from the OTDR port
102 provide OTDR monitoring of the inactive fiber path which is the
standby fiber path 20. In FIG. 5, the OTDR interoperable trunk
switch 100 has switched such that the standby fibers 20 are now
active and the OTDR signals 26, 28 provide OTDR monitoring of the
standby fibers 20. The OTDR signals 26A, 28A from the OTDR port 102
provide OTDR monitoring of the inactive fiber path which is the
primary fiber path 18 in FIG. 5.
[0032] FIG. 6 is a block diagram of an OTDR interoperable trunk
switch 100A with an OTDR port 102A which provides separate inputs
for the OTDR signals 26A, 28A thereby removing the red/blue
splitter 120. Specifically, the OTDR interoperable trunk switch
100A operates in a similar manner as the OTDR interoperable trunk
switch 100 but receives each of the OTDR signals 26A, 28A
separately and thus does not require the red/blue splitter 120.
OTDR Interoperable Trunk Switch--Single Wavelength (WL) and
Unidirectional
[0033] FIG. 7 is a block diagram of an OTDR interoperable trunk
switch 100B with an OTDR port 102B supporting a single wavelength
counter-propagating OTDR signal 28A for unidirectional OTDR
monitoring. Specifically, the OTDR interoperable trunk switch 100B
includes the splitter 12 in the transmit direction to split the
input signal 16 on the client-side port 106 to both line-side ports
110, 112. There is no OTDR signal in the transmit direction hence
the description of unidirectional OTDR monitoring. The receive
direction includes a 2.times.2 switch 30 with one input connected
to the client-side port 108 and another input connected to the OTDR
port 102B. The outputs of the 2.times.2 switch 30 connect to the
line-side ports 114, 116. With this configuration, the
counter-propagating OTDR signal 28 supports OTDR monitoring on the
active fiber in the receive direction, and the counter-propagating
OTDR signal 28A supports OTDR monitoring on the inactive fiber in
the receive direction.
OTDR Interoperable Trunk Switch--Single Wavelength (WL) and
Bidirectional
[0034] FIG. 8 is a block diagram of an OTDR interoperable trunk
switch 100C with an OTDR port 102B supporting a single wavelength
counter-propagating OTDR signal 28A along with a 1.times.2 switch
140 for bidirectional OTDR monitoring. The OTDR interoperable trunk
switch 100C is similar to the OTDR interoperable trunk switch 100
with the 2.times.2 optical switches 30A, 30B in FIG. 4, but the
red/blue splitter 120 is replaced with the 1.times.2 switch 140
which can switch an OTDR signal 142 to either the transmit
direction where the OTDR signal 142 operates as the co-propagating
OTDR signal 26 or to the receive direction where the OTDR signal
142 operates at the counter-propagating OTDR signal 28. Similar to
the OTDR interoperable trunk switch 100B, the OTDR interoperable
trunk switch 100C includes the OTDR port 102B which receives the
OTDR signal 142 which is a single wavelength OTDR signal that can
operate as either the co-propagating OTDR signal 26 or the
counter-propagating OTDR signal 28 based on the 1.times.2 switch
140 setting.
[0035] In this manner, the OTDR interoperable trunk switch 100C can
continuously monitor the active fiber with the OTDR signals 26, 28
and selectively monitor the inactive fiber in the receive direction
or the transmit direction one at a time. That is, the 1.times.2
switch 140 can send the OTDR signal 142 to either the receive
direction or the transmit direction of the inactive fiber path.
[0036] OTDR Interoperable Trunk Switch--Integrated OTDR Source
[0037] FIG. 9 is a block diagram of an OTDR interoperable trunk
switch 100D with an integrated OTDR system 150. Similar to the OTDR
interoperable trunk switch 100, 100A, 100C, the OTDR interoperable
trunk switch 100D includes the 2.times.2 switches 30A, 30B.
However, the OTDR interoperable trunk switch 100D does not include
an OTDR port. Rather, the OTDR interoperable trunk switch 100D
includes the integrated OTDR system 150 within the housing 104. The
integrated OTDR system 150 provides the OTDR signals 26, 28, 26A,
28A. The OTDR signals 26, 28 are added with the input signal 16 and
the output signal 22 via combiners 152 and the OTDR signals 26A,
28A are connected to inputs of the 2.times.2 switches 30A, 30B. The
OTDR interoperable trunk switch 100D can be used without an
external OTDR source (and without the OTDR ports 102, 102A,
102B).
Example Operation of the OTDR Interoperable Trunk Switch
[0038] FIGS. 10-14 are network diagrams of OTDR interoperable trunk
switches 100-1, 100-2 interconnected by the primary fiber path 18
and the standby fiber path 20 illustrating a sequence of events
based on a fiber cut. In FIGS. 10-14, the highlight portions
indicate the signal path. FIG. 10 illustrates normal operation
wherein the OTDR interoperable trunk switches 100-1, 100-2 are both
set to communicate over the primary fiber path 18. In FIG. 11,
there is a fiber cut 180 on the primary fiber path 18 in the
eastbound direction which is detected at the OTDR interoperable
trunk switch 100-2 by a detector 24A. In FIG. 12, the OTDR
interoperable trunk switch 100-2 switches data transmission from
the primary fiber path 18 to the standby fiber path 20 which
becomes the active fiber path. A detector 24B at the OTDR
interoperable trunk switch 100-1 detects the loss of (data) light
due to the switch by the OTDR interoperable trunk switch 100-2. In
FIG. 13, the OTDR interoperable trunk switch 100-2 switches from
the primary fiber path 18 to the standby fiber path 20 thereby
restoring bidirectional data traffic.
[0039] In FIG. 14, a highlighted path on the fiber with the fiber
cut 180 shows that the OTDR (co-propagating, counter-propagating or
both) can provide information to help localize the fault and
subsequently validate a repair.
OTDR Module
[0040] FIG. 15 is a block diagram of an OTDR module 200
interconnected to the OTDR interoperable trunk switch 100. The OTDR
module 200 can connect to the OTDR ports 102, 102A, 102B on the
OTDR interoperable trunk switches 100, 100A, 100B, 100C. Note, the
OTDR interoperable trunk switch 100D does not require an external
OTDR based on the integrated OTDR system 150. The OTDR module 200
can be a standalone, pluggable, or integrated into another module
in an optical networking system. For example, the OTDR module 200
can be integrated into a multiplexer/demultiplexer, optical
amplifier, Optical Service Channel (OSC), or the like. Those
skilled in the art will recognize optical networking systems can be
realized with modules, network elements, nodes, line cards, etc.
and the functionality of the OTDR module 200, the OTDR
interoperable trunk switches 100, 100A, 100B, 100C, 100D, etc.
contemplate various physical implementations. The OTDR module 200
is presented as an example of an OTDR system in an optical
networking system that can be used with the OTDR interoperable
trunk switches 100, 100A, 100B, 100C.
[0041] The OTDR module 200 includes a housing 202 with client-side
ports 204, 206 and line-side ports 208, 210, 212. The client-side
port 204 is for a data transmit direction, and the client-side port
206 is for a data receive direction. Note, there can be other
components which are omitted for illustration purposes, such as
multiple client-side ports connected to
multiplexers/demultiplexers, etc. For illustration purposes, the
OTDR module 200 includes a single OTDR system 220 connected to a
1.times.2 switch 222. The OTDR system 220 can monitor either the
primary fiber path or the standby fiber path (i.e., the active or
the inactive fiber path) based on the setting of the 1.times.2
switch 222. For OTDR monitoring of the inactive fiber path, the
1.times.2 switch 222 is connected to the OTDR port 102, i.e., the
line-side port 210 is connected to the OTDR port 102. The OTDR
system 220 in this example is configured with a single output with
dual wavelengths. Thus the OTDR port 102 receives a single fiber,
and the dual wavelengths are split by the red/blue splitter 120 in
the OTDR interoperable trunk switch 100.
[0042] For OTDR monitoring of the active fiber path, the 1.times.2
switch 222 is connected to a splitter 224 which splits the dual
wavelengths between the transmit direction and the receive
direction. The transmit direction includes a combiner 226 which
combines an input from the client-side port 204 with the OTDR
signal split from the splitter 224. The receive direction includes
a combiner 228 which adds the OTDR signal split from the splitter
224 towards the line-side port 212.
[0043] Although the present disclosure has been illustrated and
described herein with reference to preferred embodiments and
specific examples thereof, it will be readily apparent to those of
ordinary skill in the art that other embodiments and examples may
perform similar functions and/or achieve like results. All such
equivalent embodiments and examples are within the spirit and scope
of the present disclosure, are contemplated thereby, and are
intended to be covered by the following claims.
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