Impairment Aware Path Computation Element Method and System

1. An apparatus comprising: a receiver configured to receive a path computation element protocol (PCEP) path computation request from a path computation client (PCC), wherein the path computation request comprises an impairment validation request that directs a path computation element (PCE) to perform an impairment validation of a computed network path, wherein a type length value (TLV) is included in the impairment validation request, and wherein the TLV comprises a first Pass (P) bit that indicates whether a signal quality impairment to be validated is a link level impairment; a processor coupled to the receiver and configured to implement the PCE by: computing the computed network path after receiving the path computation request; and performing an impairment validation of the computed network path specified by the impairment validation request; and a transmitter coupled to the processor and configured to transmit a PCEP reply to the PCC, wherein the PCEP reply comprises an estimated optical signal impairment value resulting from the impairment validation of the computed network path.

2. The apparatus of claim 1 , wherein the PCEP reply further comprises the computed network path and data indicating whether validation of the computed network path was successful or unsuccessful.

3. The apparatus of claim 1 , wherein the impairment validation request comprises a type of signal quality of the computed network path which indicates a type of impairment validation to be performed, and wherein, the PCE is configured to perform the impairment validation of the computed network path based on the type of signal quality.

4. The apparatus of claim 3 , wherein the type of signal quality of the computed network path comprises at least one of Bit Error Rate (BER), Optical Signal to Noise Ratio (OSNR), OSNR margin, Polarization-Mode Dispersion (PMD), and Quality Factor (Q factor).

5. The apparatus of claim 1 , wherein the impairment validation request comprises an indicator that indicates whether the impairment validation is requested to be performed at a network path level or at a network path link level, and wherein the PCE performs the impairment validation of the computed network path based on the indicator.

6. The apparatus of claim 4 , wherein the impairment validation request comprises a threshold value that indicates a minimum or maximum value of signal quality of the computed network path or a network path link to be satisfied, and wherein the PCE performs the impairment validation of the computed network path based on the threshold value.

7. The apparatus of claim 6 , wherein the PCE performs the impairment validation of the computed network path based on the threshold value by comparing a signal quality value of the computed network path, at a path level or at a link level, to the threshold value, wherein when the threshold value comprises a minimum value, the impairment validation is successful when the signal quality value is greater than or equal to the threshold value.

8. The apparatus of claim 7 , further comprising a memory coupled to the processor and comprising a traffic engineering database (TED), wherein the TED comprises network impairment data, and wherein the PCE employs the network impairment data to determine the signal quality value of the computed network path.

9. An apparatus comprising: a processor configured to implement a path computation client (PCC); a transmitter coupled to the processor and configured to send a path computation element protocol (PCEP) path computation request to a path computation element (PCE), wherein the request directs the PCE to perform routing and wavelength assignment (RWA) and a first impairment validation of a computed network path resulting from the RWA, and wherein the request comprises a type of signal quality impairment of the computed network path which indicates a first type of impairment validation to be performed; and a receiver configured to receive a PCEP reply from the PCE, the PCEP reply comprising the computed network path and an estimated optical signal impairment value resulting from the requested validation of the computed network path, wherein a type length value (TLV) is included in the request, and wherein the TLV comprises: a first Signal Quality Type field that comprises the type of signal quality of the computed network path; a first Threshold field that comprises a threshold value that a signal quality measurement for the computed network path or a computed network path link must satisfy, and a first Pass (P) bit that indicates whether the type of signal quality impairment is a path level impairment.

10. The apparatus of claim 9 , wherein the type of signal quality of the computed network path comprises at least one of Bit Error Rate (BER), Optical Signal to Noise Ratio (OSNR), OSNR margin, Polarization-Mode Dispersion (PMD), and Quality Factor (Q factor).

11. The apparatus of claim 9 , wherein the request further comprises a threshold value that indicates a minimum or maximum value the computed network path or a network path link of the computed network path needs to satisfy to be validated.

12. A method comprising: receiving, by a processor comprising a path computation element (PCE), a path computation element protocol (PCEP) path computation request (PCReq) message from a Path Computation Client (PCC), wherein the PCReq message includes a measure of signal quality to which a computed path must conform, wherein the PCReq message comprises a signal quality measure type length value (TLV), and wherein the signal quality measure TLV comprises: a Signal Quality Type field that indicates a kind of signal quality impairment; a pass (P) bit that indicates if the signal quality impairment is a path level impairment; and a Threshold field that indicates a threshold that a signal quality measurement for a path or a link must satisfy; computing the computed path after receiving the PCReq message; performing an impairment validation of the computed path specified by the PCReq message; and transmitting a PCEP reply towards the PCC, wherein the PCEP reply comprises an estimated optical signal impairment value resulting from the impairment validation of the computed path.

13. The method of claim 12 , wherein the PCReq message comprises at least one of a Bit Error Rate (BER) limit, an Optical Signal to Noise Ratio (OSNR), an OSNR margin, a Polarization-Mode Dispersion (PMD), and a Quality Factor (Q factor).

14. The method of claim 12 , wherein the PCReq message does not comprise a BER limit, wherein no default BER limit is provisioned at the PCE, and wherein the method further comprises sending, by the PCE, an error message specifying that the BER limit must be provided.

15. The method of claim 12 , wherein the PCRep message comprises the computed path, wavelengths assigned to the computed path, and an indicator that indicates whether the computed path conforms to the threshold of the signal quality measurement of the PCReq message.

16. The method of claim 12 , wherein the PCReq message is received from the PCC via a Routing and Wavelength Assignment (RWA) coordinating PCE, and wherein the PCReq message comprises: an indicator that indicates whether more than one computed path is desired; a limit to a number of optical impairment qualified computed paths to be returned in the PCRep message; and a specified path and wavelength to be qualified by the PCE.