Optical power replacement for faulted spectrum in channel holder based optical links

Patent metadata

Field	Value
Publication number	US-10868614-B2
Application number	US-201816120654-A
Country	US
Kind code	B2
Filing date	Sep 4, 2018
Priority date	Sep 4, 2018
Publication date	Dec 15, 2020
Grant date	Dec 15, 2020

Abstract

An optical node includes one or more Optical Add/Drop Multiplexer (OADM) devices which each form a respective degree connected to an associated Optical Multiplex Section (OMS) section of a cascaded optical network including a plurality of OMS sections; and a channel holder source connected to the OADM devices, wherein the OADM device is configured to detect a local fault affecting one or more traffic signals and switch to the channel holder source to provide a respective channel holder the one or more traffic signals with a same power level and spectral location such that the respective channel holder replaces a respective traffic signal at the OADM device which is a first switching port after the fault and such that all other OADM devices at other optical nodes downstream from the fault remain switched to the one or more traffic signals due to a presence of the provided respective channel holder.

First claim

What is claimed is:

1. An optical node in a cascaded optical network comprising:
an Optical Add/Drop Multiplexer (OADM) device which forms a degree connected to an associated Optical Multiplex Section (OMS) of the cascaded optical network, wherein the cascaded optical network includes a plurality of OMSs; and
a channel holder source connected to the OADM device,
wherein the OADM device is configured to
detect a local channel fault affecting one or more traffic signals through the OADM device, switch to the channel holder source to replace a respective channel holder for each of the one or more traffic signals affected by the local channel fault, each respective channel holder replacing a same spectral location such that total power in the OMS remains constant from before the local channel fault was detected to reduce any impact on in-service channels,
switch back to the one or more traffic signals responsive to (i) detection that the local channel fault has recovered and (ii) measured signal power for the one or more traffic signals is stable over a time period, wherein the one or more traffic signals are switched back over a period of time by switching a fraction of respective spectrum at a time to minimize transients,

wherein the OADM device is a first switching port positioned downstream from the local channel fault such that other OADM devices at other optical nodes downstream from the OADM device remain switched to a respective traffic signal switch port due to a presence of the provided channel holder from the channel holder source, and wherein the channel holder is switched through the respective traffic signal switch port associated with each of the other OADM devices.

2. The optical node of claim 1 , wherein the OADM device detects the local channel fault if (i) a port associated with the one or more traffic signals reports valid power reading and (ii) the port goes from in-service (IS) to a Loss of Signal (LOS) or Loss of Light (LOL).

3. The optical node of claim 1 , wherein the one or more traffic signals traverse at least two OMS sections with the OADM device connected to a first OMS, and wherein a second OMS does not switch to associated channel holders due to lack of local fiber break detection or due to the respective channel holder presence for each of the one or more traffic signals.

4. The optical node of claim 1 , wherein the channel holder source is an Amplified Stimulated Emission (ASE) source.

5. The optical node of claim 1 , wherein the local channel fault is one of:
a degree-to-degree fiber cut to the OADM device affecting degree-to-degree connectivity,
a transmitter failure,
a fiber cut between any of the transmitter, a channel multiplexer connected to the transmitter, and the OADM device connected to the channel multiplexer,
an intra-node fiber cut at the optical node, and
an upstream fault which has signaling causing optical amplifiers on the associated OMS to shut down.

6. The optical node of claim 1 , wherein the local channel fault is an upstream fault from the optical node on an associated OMS, and wherein signaling between optical amplifiers causes the optical amplifiers to shut down within the associated OMS, leading to the optical node to detect the local channel fault.

7. A method of optical power replacement for faulted channels in a cascaded optical network, the method comprising:
at an Optical Add/Drop Multiplexer (OADM) device in an optical node, wherein the OADM device forms a degree with is connected to an associated Optical Multiplex Section (OMS) of the cascaded optical network, locally detecting a local channel fault affecting one or more traffic signals through the OADM device;
switching the one or more traffic signals to one or more associated channel holders to provide a respective channel holder for replacing each of the one or more traffic signals affected by the local channel fault, each respective channel holder replacing a same spectral location such that total power in the OMS remains constant from before the local channel fault was detected to reduce any impact on in-service channels;
switching back to the one or more traffic signals responsive to (i) detecting that the local channel fault has recovered and (ii) determining that measured signal power for the one or more traffic signals is stable over a time period, wherein the switching back is performed over a period of time to minimize transients,
wherein the OADM device is a first switching port positioned downstream from the local channel fault such that other OADM devices at other optical nodes downstream from the local OADM device remain switched to a respective traffic signal switch port due to a presence of the provided channel holder, and
wherein the channel holder is switched through the respective traffic signal switch port associated with each of the other OADM devices.

8. The method of claim 7 , wherein the locally detecting the local channel fault is responsive to (i) a port associated with the one or more traffic signals reporting a valid power reading and (ii) the port going from in-service (IS) to a Loss of Signal (LOS) or Loss of Light (LOL).

9. The method of claim 7 , wherein the one or more traffic signals traverse at least two OMSs with the OADM device connected to a first OMS, and wherein a second OMS does not switch to associated channel holders due to the respective channel holder for each of the one or more traffic signals.

10. The method of claim 7 , wherein the channel holders are provided from an Amplified Stimulated Emission (ASE) source.

11. The method of claim 7 , wherein the local channel fault is one of:
a degree-to-degree fiber cut to the OADM device affecting degree-to-degree connectivity,
a transmitter failure,
a fiber cut between any of the transmitter, a channel multiplexer connected to the transmitter, and the OADM device connected to the channel multiplexer,
an intra-node fiber cut at the optical node, and
an upstream fault which has signaling causing optical amplifiers on the associated OMS to shut down.

12. The method of claim 7 , wherein the local channel fault is an upstream fault from the optical node on an associated OMS, and wherein signaling between optical amplifiers causes the optical amplifiers to shut down, leading to the OADM device to detect the local channel fault.

13. A cascaded optical network comprising:
a plurality of optical nodes; and
a plurality of Optical Multiplex Sections (OMSs) interconnecting the plurality of optical nodes;
wherein a plurality of traffic signals are configured between the optical nodes over various OMSs,
wherein each of the plurality of optical nodes includes an Optical Add/Drop Multiplexer (OADM) device configured to
detect a local channel fault affecting one or more traffic signals through the respective OADM device,
switch to a channel holder source to replace a respective channel holder for each of the one or more traffic signals affected by the local channel fault, each respective channel holder replacing a same spectral location such that total power in the OMS remains constant from before the local channel fault to reduce any impact on in-service channels, and
switch back to the one or more traffic signals responsive to (i) detection that the local channel fault has recovered and (ii) measured signal power for the one or more traffic signals is stable over a time period, wherein the one or more traffic signals are switched back over a period of time by switching a fraction of respective spectrum at a time to minimize transients,

wherein each OADM device is a first switching port positioned downstream from the local channel fault and ot

Assignees

• Ciena Corp

Inventors

• Al Sayeed Choudhury A
• Bownass David C
• Boertjes David W
• Kohlert Scott

Classifications

• H04B10/03 Primary

  Arrangements for fault recovery · CPC title

• H04J14/021

  Reconfigurable arrangements, e.g. reconfigurable optical add/drop multiplexers [ROADM] or tunable optical add/drop multiplexers [TOADM] · CPC title

• H04B10/0791 Primary

  Fault location on the transmission path · CPC title