Scaling WDM Slotted Ring Networks

Alberto Bononi Universit a di Parma { Dipartimento di Ingegneria dell'Informazione { Viale delle Scienze, I-43100 Parma, Italy phone: +39-521-905-760 fax: +39-521-905-758 { email: [email protected] Abstract| Using analogies between the basic theory of cell switching for datagram networks and multiwavelength slotted optical networks, we show that the bu ering capabilities of high-speed slotted networks, also known as spacereuse, allows multihop networks such as WDM rings to have larger throughputs than star networks, where space reuse is not possible. By nding correspondences with the classical switching theory, WDM ring networks are extensively analyzed in uniform tra c. The multihop nature of the network, and the clear identi cation of the meaning of hop as it relates to throughput, help identify a novel generalized ring topology, which we call WDM Chordalring, which smoothly scales the throughput of a WDM ring by progressively adding WDM unbu ered routers up to reaching the desired saturation throughput. Routing without bu ers is studied in the novel topology by simulation, and an empirical routing scheme is found that gives satisfactory performance. Using such scheme, the topology is optimized and a clear trade-o between number of wavelengths, number of receivers per node and number of routers is identi ed and quanti ed.