Fast lightpath restoration becomes particularly challenging in all-optical networks. First, the optical transparency complicates failure localization and isolation procedures, as loss of light alarms stemming from a failure propagate downstream from the failure point. Besides, such a transparency implies that optical signals must traverse relatively long distances without electrical regeneration. In view of this, backup path computations must also account for all degradations introduced in the physical end-to-end path, thus ensuring their feasibility. Looking toward the optical core networks of the future, the EU DICONET Project has worked on cross-layer solutions to enhance network control and management with the impairment-awareness needed to govern the underlying optical layer. This includes a network planning and operation tool (NPOT) that implements impairment-aware routing and wavelength assignment algorithms, along with a failure localization mechanism. This paper reports the experimental demonstration of a dynamic impairment-aware restoration scheme that benefits from enhanced NPOT features for fast lightpath restoration. To this end, a prioritized scheduler to provide differentiated resilience support, the implementation of the quality of transmission estimator module on field programmable gate array hardware, and a fast resource pre-reservation protocol are presented in this work. The performance of the proposed impairment-aware lightpath restoration scheme has been evaluated experimentally on a 14-node all-optical network test-bed, showing average restoration times of 1.16 and 1.64 s for high and low priority traffic classes, respectively.
- Failure restoration
- Optical networks