Fractional lambda switching principles of operation and performance issues

This article introduces fractional lambda (lambda) switching (FlambdaS) and studies its blocking issues. FlambdaS uses a global common time reference (CTR) for implementing pipeline forwarding (PF) inside the network. A global CTR is conveniently realized with the UTC (coordinated universal time) standard. Resource reservation over an FlambdaS network requires a schedule. As in other scheduling cases, a call may not be accepted, even though there is enough capacity, because the schedule is not available-the call is then considered blocked. This work studies the probability of call blocking as a function of link utilization. The results show that (especially if multiple-wavelength division multiplexing channels are deployed on optical links between fractional lambda switches) high-link utilization can be achieved with negligible call blocking, even when the switching fabric is a Banyan network.