Dynamic Intelligent MAC Protocol for Metropolitan Optical Packet Switching Ring Networks

This paper presents a new access protocol addressing the problem of inefficient utilization of bandwidth and the fairness issue in metropolitan optical packet switching ring (OPSR) networks. This protocol, called Dynamic Intelligent - Medium Access Control (DI-MAC) protocol, greatly improves the performance of the OPSR network that usually employs the optical Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol. The principle of DI-MAC is to intelligently space out the transmission of local packets at upstream nodes to avoid inefficient bandwidth fragmentation and, as a result, to release more bandwidth for downstream nodes. The key feature of DI-MAC is that it automatically and dynamically adjusts the gap between successive transmission of local packets, according to the change of network state (i.e., bandwidth availability, traffic variation, etc.), in order to favor the transmission of downstream nodes, and at the same time, to satisfy requirements of local clients in terms of quality of service. Our experiments shown that DI-MAC effectively simplifies the network management and optimizes the network performance; thus it promises to be a new cost-efficient access protocol for future metropolitan optical ring networks. In this paper, we explain in detail this protocol and analyze its impact on the network performance.