A multi-stage switching architecture is a key technology for building a high-speed ATM switching system. An effective way to make a multi-stage switch nonblocking is to use cell-based routing. However, cell-based routing may cause cell-sequence disorder at the output of the switching fabric. This paper proposes a hierarchical cell-sorting (HCS) switch architecture, which is a nonblocking multi-stage ATM switch using cell-based routing technology. Each basic HCS switch performs cell sorting at every crosspoint, based on timestamp information in the cell-header. This arranges the cells in sequence at the output of each basic HCS switch, since the crosspoints are hierarchically interconnected from the input port to the output port of a basic HCS switch. A multi-stage HCS switch is constructed by interconnecting the input and output lines of these basic HCS switches in a hierarchical manner. Thus, the cell sequence in each final output of the multi-stage switch is preserved in a hierarchical manner. In this way, cell-based routing with 100% throughput is achieved, with no need for internal speed-up techniques.
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