The evolution of space division packet switches

This paper traces the evolution of packet switches which employ an arrangement of multiple simultaneous paths, typically called 'switch fabrics'. These space-division packet switches represent recent advances in fast packet technology. Such switches offer reduced delay and increased throughput to satisfy the requirement of more bandwidth per user and of larger switch dimensions which can not be satisfied with reasonably sized packet switches employing the time-division multiplexing principle as in shared bus or ring structures. We trace the evolution of space-division packet switches by discussing, among others, Banyan networks and various variations, the packet-synchronous networks of the Balcher-Banyan type, and a packet-asynchronous approach with multiple alternate routes. These and other fabrics and the switches built using them are contrasted in terms of the capabilities of their most recent versions, including buffering techniques, types of data handled, feasibility of physical implementation and compatibility with proposed standards and protocols.