Optical ring networks using circulating optical probe in protection switching with automatic reversion
First Claim
1. A method for optical protection switching in a dual-fiber optical ring network in which a plurality of network nodes is interconnected by a first fiber optic cable for signals propagating in a clockwise direction and a second fiber optic cable for signals propagating in a counterclockwise direction, the method including the following steps:
- (a) generating and terminating, at a first of the plurality of network nodes, a first and second circulating optical probe signal that propagate to each of the plurality of network nodes along the respective first and second fiber optic cables, wherein the first and second optical probe signals are retransmitted without undergoing an optical to electrical conversion at each of the plurality of network nodes, and are generated at optical wavelengths different from those of optical wavelength-division multiplexed (WDM) signals carrying data and control information that must be retransmitted by undergoing the optical to electrical conversion at each of the plurality of network nodes;
(b) monitoring the first and second optical probe signals to detect the presence of an optical failure in the optical ring network, wherein the detection of an optical break point in at least one of the optical probe signals indicates the presence of an optical failure in the optical ring network, and wherein the absence of an optical break point in both the first and second optical probe signals indicates normal operation of the optical ring network; and
(c) controlling a protection switch mechanism, in response to the detection of an optical failure, to sustain communications in the optical ring network outside a location of the optical failure, and to restore communications in the optical ring network in response to the subsequent detection of normal operation of the optical ring network, indicating that the optical failure has been repaired.
7 Assignments
0 Petitions
Accused Products
Abstract
Techniques and apparatus for optical communication networks including fiber ring networks with protection switching to maintain optical communications when an optical failure occurs and to automatically revert to normal operation when the optical failure is corrected. Implementations include use of a circulating optical probe signal at an optical probe wavelength within the gain spectral range of optical amplifiers used in a fiber ring network to detect an optical failure.
121 Citations
16 Claims
-
1. A method for optical protection switching in a dual-fiber optical ring network in which a plurality of network nodes is interconnected by a first fiber optic cable for signals propagating in a clockwise direction and a second fiber optic cable for signals propagating in a counterclockwise direction, the method including the following steps:
-
(a) generating and terminating, at a first of the plurality of network nodes, a first and second circulating optical probe signal that propagate to each of the plurality of network nodes along the respective first and second fiber optic cables, wherein the first and second optical probe signals are retransmitted without undergoing an optical to electrical conversion at each of the plurality of network nodes, and are generated at optical wavelengths different from those of optical wavelength-division multiplexed (WDM) signals carrying data and control information that must be retransmitted by undergoing the optical to electrical conversion at each of the plurality of network nodes; (b) monitoring the first and second optical probe signals to detect the presence of an optical failure in the optical ring network, wherein the detection of an optical break point in at least one of the optical probe signals indicates the presence of an optical failure in the optical ring network, and wherein the absence of an optical break point in both the first and second optical probe signals indicates normal operation of the optical ring network; and (c) controlling a protection switch mechanism, in response to the detection of an optical failure, to sustain communications in the optical ring network outside a location of the optical failure, and to restore communications in the optical ring network in response to the subsequent detection of normal operation of the optical ring network, indicating that the optical failure has been repaired. - View Dependent Claims (2, 3, 4)
-
-
5. A method for optical protection switching in a dual-fiber optical ring network in which a plurality of network nodes is interconnected by a first fiber optic cable for signals propagating in a clockwise direction and a second fiber optic cable for signals propagating in a counterclockwise direction, the method including the following steps:
-
(a) generating and terminating, at a first of the plurality of network nodes, a first and second circulating optical probe signal that propagate to each of the plurality of network nodes along the respective first and second fiber optic cables, wherein the first and second optical probe signals are retransmitted without undergoing an optical to electrical conversion at each of the plurality of network nodes, and are generated at optical wavelengths different from those of optical wavelength-division multiplexed (WDM) signals carrying data and control information that must be retransmitted by undergoing the optical to electrical conversion at each of the plurality of network nodes; (b) creating, at the first of the plurality of network nodes, a default protective break point on the first and second fiber optic cables; (c) monitoring the first and second optical probe signals to detect the presence of an optical failure in the optical ring network, wherein the detection of an optical break point in at least one of the optical probe signals indicates the presence of an optical failure in the optical ring network, and wherein the absence of an optical break point in both the first and second optical probe signals indicates normal operation of the optical ring network; and (d) controlling a protection switch mechanism, in response to the detection of an optical failure, to replace the default protective break point at the first of the plurality of network nodes with a protective break point at one or more network nodes adjacent to the location of the optical failure, and to replace the protective break point with the default protective break point in response to the subsequent detection of normal operation of the optical ring network, indicating that the optical failure has been repaired. - View Dependent Claims (6, 7, 8)
-
-
9. An optical protection switching controller in a dual-fiber optical ring network in which a plurality of network nodes is interconnected by a first fiber optic cable for signals propagating in a clockwise direction and a second fiber optic cable for signals propagating in a counterclockwise direction, the controller comprising:
-
(a) a first and second circulating optical probe signal, generated and terminated at a first of the plurality of network nodes, that propagate to each of the plurality of network nodes along the respective first and second fiber optic cables, wherein the first and second optical probe signals are retransmitted without undergoing an optical to electrical conversion at each of the plurality of network nodes, and are generated at optical wavelengths different from those of optical wavelength-division multiplexed (WDM) signals carrying data and control information that must be retransmitted by undergoing the optical to electrical conversion at each of the plurality of network nodes; (b) an optical failure detector that monitors the first and second optical probe signals, wherein the detection of an optical break point in at least one of the optical probe signals indicates the presence of an optical failure in the optical ring network, and wherein the absence of an optical break point in both the first and second optical probe signals indicates normal operation of the optical ring network; and (c) a protection switch mechanism that, in response to the detection of an optical failure, sustains communications in the optical ring network outside a location of the optical failure, and restores communications in the optical ring network in response to the subsequent detection of normal operation of the optical ring network, indicating that the optical failure has been repaired. - View Dependent Claims (10, 11, 12)
-
-
13. An optical protection switching controller in a dual-fiber optical ring network in which a plurality of network nodes is interconnected by a first fiber optic cable for signals propagating in a clockwise direction and a second fiber optic cable for signals propagating in a counterclockwise direction, the controller comprising:
-
(a) a first and second circulating optical probe signal, generated and terminated at a first of the plurality of network nodes, that propagate to each of the plurality of network nodes along the respective first and second fiber optic cables, wherein the first and second optical probe signals are retransmitted without undergoing an optical to electrical conversion at each of the plurality of network nodes, and are generated at optical wavelengths different from those of optical wavelength-division multiplexed (WDM) signals carrying data and control information that must be retransmitted by undergoing the optical to electrical conversion at each of the plurality of network nodes; (b) a default protective break point created at the first of the plurality of network nodes on the first and second fiber optic cables; (c) an optical failure detector that monitors the first and second optical probe signals, wherein the detection of an optical break point in at least one of the optical probe signals indicates the presence of an optical failure in the optical ring network, and wherein the absence of an optical break point in both the first and second optical probe signals indicates normal operation of the optical ring network; and (d) a protection switch mechanism that, in response to the detection of an optical failure, replaces the default protective break point at the first of the plurality of network nodes with a protective break point at one or more network nodes adjacent to the location of the optical failure, and replaces the protective break point with the default protective break point in response to the subsequent detection of normal operation of the optical ring network, indicating that the optical failure has been repaired. - View Dependent Claims (14, 15, 16)
-
Specification