QoT-guaranteed protection: Survivability under physical layer impairments

As physical layer impairments play a large role in determining the ultimate performance of all-optical networks, it has attracted much attention. However, traditional survivability schemes have been designed and utilized without considering the quality of transmission at the physical layer. Recently, a few studies on QoT-aware (quality of transmission) protection were initiated to meet the reliability needs of future communications infrastructures. In this paper, we present a study of how transmission impairments caused by non-ideal characteristics of network components (such as amplifier spontaneous emission noise and crosstalk) affect the survivability under various QoT-aware protection schemes. We present heuristic QoT-guaranteed protection RWA for dynamic provisioning that forgoes multiple bit-error-rate calculations, and quantify the performance of various QoT-aware schemes. We also evaluate the tradeoff between using crosstalk-free Banyan switches and utilizing switch plane selection with non-crosstalk-free designs. It is expensive to provide QoT-guaranteed protection, but the usefulness of QoT-aware (nonguaranteed) schemes, while cost-effective, depends on the topology. Our results also show that QoT-unaware algorithms, while performing significantly worse in terms of blocking, can have slightly better post-failure performance.