Metropolitan area packet-switched WDM networks: A survey on ring systems

We provide a comprehensive survey of packet-switched ring metro WDM networks. We first review current standardization and testbed activities, then we provide a categorization of ring WDM networks. We structure our survey according to a classification of the medium access control (MAC) protocols employed in the networks. Throughout the article we pay close attention to the key factors that govern the throughput-delay performance of the networks, such as the source vs. destination stripping of the data packets from the ring and the a priori or a posteriori access strategies. We also consider fairness aspects and QoS support in the networks.