Virtual topologies for WDM star LANs-the regular structures approach

The design of a wavelength division multiplexing (WDM) passive star network must address the following limitations of the optical hardware technologies: a limited number of transmitters and receivers at each node; the unavailability of rapidly tuning transmitters and receivers; and the mismatch between the electronic processing rates and the optical transmission bandwidth. The authors investigate the use of regular virtual topologies as an efficient solution that incorporates the above hardware limitations, while providing high system utilization and low end-to-end delays. The following regular topologies are investigated: Shufflenet, binary hypercube, generalized hypercube, and two-dimensional torus. A number of performance and hardware related metrics are introduced that reflect the use of these topologies in a high speed optical environment. Based on these metrics, along with upper and lower bounds developed for performance and hardware requirements, the authors evaluate and compare the selected regular topologies. They also address the issue of mapping the regular virtual topologies into a WDM star network