On the capacity of MAC protocols for all-optical WDM multi-rings with tunable transmitters and fixed receivers

The paper considers medium access control protocols for all-optical packet networks based on WDM multichannel ring topologies where nodes are equipped with one fixed-wavelength receiver and one wavelength-tunable transmitter. Such networks provide separate channels for slotted transmissions to disjoint subsets of destination nodes. Some simple access protocols based on local status information are described. Since these protocols are not able to enforce fairness by themselves, fairness control algorithms derived from those adopted in the Metaring high-speed metropolitan area network are also proposed. Analytical and simulation results are presented to assess the capacity of the proposed protocols in uniform traffic conditions, with a particular focus on the case where at each node the packet to be transmitted is randomly selected. In spite of the simplicity of the proposed access schemes, numerical results show that good performance can be achieved and the fairness problems inherent in the considered network topologies can be overcome.