QoS support and fairness control in a slotted packet-switched WDM metro ring network

In this paper, a novel distributed medium access protocol for a time-slotted WDM metro ring employing all-optical packet switching and supporting QoS classes directly in the optical layer is presented and analyzed. Since we assume much more nodes than available wavelengths in the network, we obtain a scalable multi-hop WDM ring. In our architecture, each node is equipped with one tunable transmitter and one fixed-tuned receiver. The new QoS control scheme adopts a frame-based slot reservation strategy including connection set-up and release, thus efficiently combining connection-less and connection-oriented services. Furthermore, a fairness control scheme, named M(ultiple)-ATMR, guaranteeing fairness for best-effort traffic through a credit-based mechanism is proposed.