A MAC protocol for efficient multiplexing QoS-sensitive and best-effort traffic in dynamically configurable WDM rings

Slotted dynamically re-configurable Metropolitan rings are viewed as a viable alternative to WDM channel overprovisioning since they allow statistical sharing between the channels. A challenge these networks are facing is to simultaneously transport both delay sensitive and best-effort traffic. In this work, a strategy for mixing up different QoS classes efficiently in a dynamically re-configurable ring is proposed. The scheme is based on explicit class reservations for the delay-sensitive first priority traffic, which are allowed to fluctuate in accordance with demand. In contrast, best effort traffic is using only any bandwidth left over by the high QoS traffic, thus exploiting the elastic behaviour of best-effort traffic and its closed loop control. The performance of the proposed mechanism is evaluated via simulations demonstrating access delay below the round trip time for high priority traffic and good overall system efficiency by filling any spare capacity with best-effort traffic, which was buffered during busy periods.