Use of subcarrier deactivation in a multi-subcarrier channel to improve reach in an optical network

1. A method comprising:

transmitting a data signal over a path of a wavelength-division multiplexed (WDM) optical network via an optical channel allocated as a group of optical subcarriers;

determining that a hop-to-hop route for the path has been changed or rerouted;

determining that the transmission of the data signal over the rerouted path using the group of optical subcarriers is not optically feasible;

determining that the transmission of the data signal over the changed or rerouted path using a subset of optical subcarriers selected from the group of optical subcarriers is optically feasible;

selecting the subset of optical subcarriers such that the data signal is carried in the optical channel in active subcarriers of the subset of optical subcarriers that are separated by at least one inactive subcarrier of the group of optical subcarriers; and

transmitting the data signal in the optical channel over the changed or rerouted path of the WDM network using the active optical subcarriers of the subset of optical subcarriers.

2. The method of claim 1 and wherein the subset of optical subcarriers provides a lower data rate or bandwidth for transmitting the data signal as compared to the group of optical subcarriers, the method further comprising sending a message to an upstream node such that, in response to the message, the data rate or bandwidth of the data signal at the upstream node is reduced in accordance with the lower data rate or bandwidth.

3. The method of claim 1 , wherein determining that the transmission of the data signal over the changed or rerouted path using a subset of the group of optical subcarriers is optically feasible comprises at least one of:

performing, either via a central controller or via a distributed optical control plane, an optical feasibility calculation for the changed or rerouted path and the subset of optical subcarriers; or

determining that the changed or rerouted path and the subset of optical subcarriers matches a pre-validated path in a list of pre-validated paths, wherein each pre-validated path in the list of pre-validated paths was previously determined to be optically feasible.

4. The method of claim 1 , wherein determining that the transmission of the data signal over the changed or rerouted path using the group of optical subcarriers is not optically feasible comprises:

sending a message to request that an optical feasibility calculation be performed via an optical control plane (OCP) controller provided at two or more of a plurality of nodes along the changed or rerouted path of the WDM optical network; and

receiving a reply message from one of the OCP controllers along the changed or rerouted path of the WDM optical network indicating that the transmission of the data signal over the changed or rerouted path using the group of optical subcarriers is not optically feasible.

5. The method of claim 1 , wherein determining that the transmission of the data signal over the changed or rerouted path using the subset of optical subcarriers is optically feasible comprises:

sending a message to request that an optical feasibility calculation be performed in a distributed manner by an optical control plane (OCP) controller provided at two or more of a plurality of nodes along the changed or rerouted path of the WDM optical network; and

receiving a reply message from one of the OCP controllers along the changed or rerouted path of the WDM optical network indicating that the transmission of the data signal over the changed or rerouted path using the subset of optical subcarriers is optically feasible.

6. The method of claim 1 , wherein determining that the transmission of the data signal over the changed or rerouted path using the group of optical subcarriers is not optically feasible comprises:

comparing one or more parameters describing the changed or rerouted path and the group of optical subcarriers to one or more parameters in a list of pre-validated paths for the WDM optical network, each pre-validated path identifying an optically feasible label switched path in the WDM network; and

determining that there is not a pre-validated path on the list that matches the changed or rerouted path and the group of optical subcarriers.

7. The method of claim 1 , wherein determining that the transmission of the data signal over the changed or rerouted path using the subset of optical subcarriers is optically feasible comprises:

comparing one or more parameters describing the changed or rerouted path and the subset of optical subcarriers to one or more parameters in a list of pre-validated paths for the WDM optical network, each pre-validated path identifying an optically feasible label switched path in the WDM network; and

determining that there is a pre-validated path on the list that matches the changed or rerouted path and the subset of optical subcarriers.

8. An apparatus comprising:

a transponder including a plurality of lasers including at least one laser for each of a plurality of subcarriers of optical subcarriers;

at least one processor; and

at least one memory including computer program code, the computer program code, when executed by the processor, configured to cause the apparatus to:

activate the plurality of lasers to transmit a data signal in an optical channel allocated as the group of optical subcarriers over a path of a wavelength-division multiplexed (WDM) optical network;

determine that a hop-to-hop route for the path has been changed or rerouted;

determine that the transmission of the data signal in the optical channel over the changed or rerouted path using the group of optical subcarriers is not optically feasible;

determine that the transmission of the data signal over the changed or rerouted path using a subset of optical carriers selected from the group of optical subcarriers is optically feasible; and

deactivate one or more of the plurality of lasers to cause one or more of the subcarriers of the group of optical subcarriers to be inactive while allowing the subset of optical subcarriers to remain active; and

transmit the data signal in the optical channel over the changed or rerouted path of the WDM network using the subset of optical subcarriers via the activated lasers such that at least one inactive subcarrier separates two active subcarriers within the subset of optical subcarriers.

9. The apparatus of claim 8 , wherein processor and computer code being configured to cause the apparatus to determine that the transmission of the data signal over the changed or rerouted path using the subset of optical subcarriers is optically feasible comprises the processor and computer code being configured to cause the apparatus to:

send a message to request that an optical feasibility calculation be performed in a distributed manner by an optical control plane (OCP) controller provided at two or more of a plurality of nodes along the changed or rerouted path of the WDM optical network; and

receive a reply message from one of the OCP controllers along the changed or rerouted path of the WDM optical network indicating that the transmission of the data signal over the changed or rerouted path using the subset of optical subcarriers is optically feasible.

10. The apparatus of claim 8 , wherein processor and computer code being configured to cause the apparatus to determine that the transmission of the data signal over the rerouted path using the group of optical subcarriers is not optically feasible comprises the processor and computer code being configured to cause the apparatus to:

compare one or more parameters describing the changed or rerouted path and the group of optical subcarriers to one or more parameters in a list of pre-validated paths for the WDM optical network, each pre-validated path identifying an optically feasible label switched path in the WDM network; and

determine that there is not a pre-validated path on the list that matches the changed or rerouted path and the group of optical subcarriers.

11. The apparatus of claim 8 , wherein processor and computer code being configured to cause the apparatus to determine that the transmission of the data signal over the changed or rerouted path using the subset of optical subcarriers is optically feasible comprises the processor and computer code being configured to cause the apparatus to:

compare one or more parameters describing the changed or rerouted path and the subset of optical subcarriers to one or more parameters in a list of pre-validated paths for the WDM optical network, each pre-validated path identifying an optically feasible label switched path in the WDM network; and

determine that there is a pre-validated path on the list that matches the changed or rerouted path and the subset of optical subcarriers.

12. An apparatus comprising:

at least one processor; and

at least one memory including computer program code, the computer program code, when executed by the processor, configured to cause the apparatus to:

allocate an optical channel in a wavelength-division multiplexed (WDM) optical network comprising a group of optical subcarriers;

activate a plurality of lasers, with at least one laser for each of a plurality of optical subcarriers of a group of optical subcarriers;

transmit a data signal in an optical channel comprising the group of optical subcarriers over a path of a wavelength-division multiplexed (WDM) optical network;

determine that a hop-to-hop route for the path has been changed or rerouted;

determine that the transmission of the data signal over the changed or rerouted path using the group of optical subcarriers is not optically feasible;

determine that the transmission of the data signal over the changed or rerouted path using a subset of optical subcarriers selected from the group of optical subcarriers is optically feasible;

deactivate one or more of the plurality of lasers to cause one or more of the subcarriers of the group of optical subcarriers to be inactive while allowing the subset of optical subcarriers to remain active; and

transmit the data signal in the optical channel over the rerouted path of the WDM network using the subset of optical subcarriers via the activated lasers such that at least one inactive subcarrier separates two active subcarriers within the subset of optical subcarriers.

13. A method comprising:

determining that a transmission of a data signal in an optical channel allocated as a group of optical subcarriers over a path of a wavelength division multiplexed (WDM) optical network is not optically feasible;

determining that the transmission of the data signal over the path using a subset of optical subcarriers selected from the group of optical subcarriers is optically feasible;

activating the subset of optical carriers subcarriers while deactivating one or more optical subcarriers of the group of optical subcarriers such that the data signal is carried in the optical channel via the subset of optical subcarriers in at least two activated subcarriers of the subset of optical subcarriers separated by at least one deactivated subcarrier of the group of optical subcarriers; and

transmitting the data signal in the optical channel over at least a portion of the path using the activated subcarriers of the subset of optical subcarriers.

14. The method of claim 13 and further comprising receiving, from a requesting node, a resource request to transmit the data signal within the WDM optical network via the optical channel allocated as the group of the optical subcarriers.

15. The method of claim 14 , wherein resource request identifies requested resources for the optical channel so that the data signal can be conveyed therein, and wherein the activated subcarriers of the subset of optical subcarriers comprise less than the requested resources, the method further comprising sending a flow control message to the requesting node to request a reduced data rate for the data signal or indicating that resources will be provided at a rate less than the resources requested.

16. The method of claim 13 , wherein a laser is provided for each of the optical subcarriers of the group, the method further comprising activating a laser for each of the activated optical subcarriers of the subset of optical subcarriers and deactivating a laser for each of one or more deactivated optical subcarriers of the group of optical subcarriers.

17. The method of claim 13 , wherein determining that the transmission of the data signal over the path of the WDM optical network using the group of optical subcarriers is not optically feasible is performed in response to detecting a change in a hop-to-hop route for the path.

18. The method of claim 13 , wherein determining that the transmission of the data signal over the path using the subset of optical subcarriers is optically feasible comprises at least one of:

performing, either via a central controller or via a distributed optical control plane, an optical feasibility calculation for the path and the subset of optical subcarriers; or

determining that the path and the subset of optical subcarriers matches a pre-validated path in a list of pre-validated paths, wherein each pre-validated path in the list of pre-validated paths was previously determined to be optically feasible.

19. The method of claim 13 , wherein determining that the transmission of the data signal over the path using the subset of optical subcarriers is optically feasible comprises:

sending a message to request that an optical feasibility calculation be performed in a distributed manner by an optical control plane (OCP) controller provided at two or more of a plurality of nodes along the path of the WDM optical network; and

receiving a reply message from one of the OCP controllers along the rerouted path of the WDM optical network indicating that the transmission of the data signal over the path using the subset of optical subcarriers is optically feasible.

20. An apparatus comprising:

at least one processor; and

at least one memory including computer program code, the computer program code, when executed by the processor, configured to cause the apparatus to:

determine that a transmission of a data signal over a path of a wavelength division multiplexed (WDM) optical network in an optical channel comprising a group of optical subcarriers is not optically feasible;

determine that the transmission of the data signal over the path using a subset of optical subcarriers selected from the group of optical subcarriers is optically feasible;

activate the subset of optical subcarriers while deactivating one or more optical subcarriers of the group of optical subcarriers such that at least one deactivated subcarrier separates at least two activated subcarriers of the subset of optical subcarriers; and

transmit the data signal in the optical channel over at least a portion of the path using the activated subcarriers of the subset of optical subcarriers.

21. The apparatus of claim 20 , wherein processor and computer program code configured to cause the apparatus to activate the subset of optical subcarriers comprises the processor and computer program code configured to cause the apparatus to activate a laser for each of the activated subcarriers; and

wherein, the processor and computer program code configured to cause the apparatus to deactivate subcarriers of the group comprises the processor and computer program code configured to cause the apparatus to deactivate a laser for each of one or more of the deactivated optical subcarriers of the group of optical subcarriers.

22. The apparatus of claim 20 and further comprising a plurality of lasers including at least one laser for each of a plurality of the subcarriers of the group of optical subcarriers, wherein the processor and computer program code configured to cause the apparatus to activate the subset of optical subcarriers comprises the processor and computer program code configured to cause the apparatus to activate the laser for each of the activated subcarriers of the subset of optical subcarriers; and

wherein, the processor and computer program code configured to cause the apparatus to deactivate subcarriers of the group of optical subcarriers comprises the processor and computer program code configured to cause the apparatus to deactivate the laser for each of one or more of the deactivated optical subcarriers of the group of optical subcarriers.