Strict-sense nonblocking networks with three multiplexing and switching levels

Changes in traffic characteristics impose new requirements on interconnection network in large data centers. These requirements force changes to be done in the network architecture and used technology. Traditional tree network topology is being replaced by Clos network, called also Leaf-Spine topology, and optical interconnection networks are added in parallel to conventional electronic switching networks. Circuit switching is also used in such network instead of packet switching. In this paper we analyze the three-stage Clos network in which three multiplexing schemes are used simultaneously on input, output, and interstage links and with circuit switching mode. Strict-sense nonblocking conditions for this network with three multiplexing levels (space, wavelength, and mode) are derived and proved. Up till now such network with at most two multiplexing levels (space and time, or space and wavelength) has been considered.