In this study, we consider wide-sense nonblocking operation of a converting-space-converting switching fabric. We propose a routing strategy based on the functional decomposition of second-stage switches, called the XsVarSWITCH routing strategy. This routing strategy is suitable for all kinds of three-stage switching fabrics operating in a slotted mode, regardless of frequency, time, or other types. We consider in this study a three-stage switching fabric. The first and third stages comprise switches with converting capability, while the middle stage is composed of space switches. The proposed routing strategy can reduce the number of required center-stage switches by almost 94% in some cases, as compared to the number of middle-stage switches under strict-sense nonblocking conditions.

In this paper, we study the wide-sense nonblocking operation for the Converting-Space-Converting switching fabric architecture. The investigated switching fabric is suitable for all kinds of slot-operating switches, no matters the slots are wavelengths, time, or others. One control algorithm for the mentioned architecture is proposed. The control algorithm decomposes the slots in the interstage links into X subsets. The proposed algorithm can reduce the required number of slots in the interstage links by almost 84%, as compared to the number of slots required in the strict sense.

In this paper, we address the problem of the strict-sense nonblocking operation of an elastic optical switch. Elastic optical switches are used as nodes in elastic optical networks (EONs), where fine granular frequency slots or flexible grids are used in opposite to the traditional optical networks, where fixed grids are used. The switch architecture considered in this paper consists of waveband converting switches in input and output stages, while in the center stage there is only one wavelength selective space switch without wavelength conversion capabilities. We derive the number of frequency channels k needed in interstage links to ensure the nonblocking operation of the switch when input and output links have n frequency channels and a frequency slot of one connection is not greater than m frequency channels. Both, necessity and sufficient conditions are proved.