This work proposes a distributed fault protection mechanism called the Dynamic-Shared Segment Protection (DSSP) algorithm for WDM (Wavelength Division Multiplexing) mesh networks. The objects are to assure high probability of path protection and efficient use of network resources. The proposed approach exploits the segment protection mode, which accommodates the characteristics of both path-based and link-based protections, for providing finer service granularities, to satisfy the versatile requirements of critical applications in the foreseeable future. To show that DSSP can improve performance efficiency, simulations are conducted using four networks (NSFNET, USANET, Mesh 66, Mesh 99) for a comparative study of the proposed DSSP versus ordinary shared protection schemes and SLSP (Short Leap Shared Protection). Simulation results reveal that the proposed DSSP method results in much lower blocking probability and has higher network utilization. Consequently, it is very useful for applications to a real-time WDM network, which changes status dynamically.

Ethernet passive optical network (EPON) is one of the energy-efficient access networks. Many studies have been done to reach maximum energy saving in the EPON. However, it is a trade-off between achieving maximum energy saving and guaranteeing QoS. In this paper, a predictive doze mode mechanism in an enhanced EPON architecture is proposed to achieve energy saving by using a logistic regression (LR) model. The optical line terminal (OLT) in the EPON employs an enhanced Doze Manager practicing the LR model to predict the doze periods of the optical network units (ONUs). The doze periods are estimated more accurately based on the historical high-priority traffic information, and logistic regression DBA (LR-DBA) performs dynamic bandwidth allocation accordingly. The proposed LR-DBA mechanism is compared with a scheme without energy saving (IPACT) and another scheme with energy saving (GDBA). Simulation results show that LR-DBA effectively improves the power consumption of ONUs in most cases, and the improvement can be up to 45% while it guarantees the QoS metrics, such as the high-priority traffic delay and jitter.