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A three-stage Clos switch architecture is attractive because of its scalability. From an implementation point of view, it allows us to relax the cooling limitation, but there is a problem interconnecting different stages. This article presents a three-stage switching system that uses optical WDM grouped links and dynamic bandwidth sharing. We call it a WDM grouped-link switch. The introduction of WDM makes the number of cables used in the system proportional to the switch size. Dynamic bandwidth sharing among WDM grouped links prevents the statistical multiplexing gain offered by WDM from falling even if the switching system becomes large. The WDM grouped-link switch uses cell-by-cell wavelength routing. A performance evaluation confirms the scalability and cost-effectiveness of this switch. An implementation of the WDM grouped link and a compact planar lightwave circuit platform is described. This architecture allows us to expand the throughput of the switching system up to 5 Tb/s.
Date of Publication: Oct 2003