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Optimal Non-blocking Switches

New cost-efficient designs and routing algorithms - the theoretical results provide the first major breakthrough in this area since the pioneering works of C. Clos (1953) and V. Benes (1962) of Bell Labs. The proposed designs are two-sided multistage interconnection network (MIN) built of switching elements of desirable sizes. They are optimally compact and scalable to virtually any size N×M (i.e. having N input and M output ports). Each design is supplied with a highly efficient routing algorithm. The hardware saving is approximately 30-60% compared to best-known conventional designs of the same functionality. The saving is especially great for odd, asymmetric and large switch sizes. It is achieved by utilizing less number of switching elements, possibly reducing their size and, consequently, reducing the total cost of switching elements and the number of inter-stage links. The great hardware saving would also affect the physical size of the switch, its reliability, and provide more possibilities for higher security and fault tolerance features. Moreover, the proposed designs minimize the number of stages, which is critical for some application with power loss issues. In addition to that the switches allow modular construction and can have various additional non-blocking properties such as multi-casting and loop-backs. The new designs can find variety of applications in ever expanding telephony and computer networks, DSL, photonic switching, parallel processing, etc.

Functionally, the proposed 2-sided non-blocking switching networks can be divided into the following 4 categories:

Conventional Rearrangeable (CR)
Non-interruptive rearrangeable (NIR)
Wide-sense non-blocking (WNB)
Virtually non-blocking (VNB)

The major common feature of a 2-sided non-blocking network is that it can simultaneously connect all its source input ports (inputs) to its destination ports (outputs) in a one-to-one manner for all possible permutations of input-to-output pairings. For scheduled traffic there is no essential difference between the above categories. However, they differ in network ability to handle dynamic traffic. CR networks are also called rearrangeably non-blocking networks, and NIR networks were initially introduced as hitlessly rearrangeable networks. In what follows we overview the main properties and application of each category of the proposed networks.