High-speed multi-stage ATM switch based on hierarchical cell resequencing architecture and WDM interconnection

This paper proposesd a non-blocking multistage ATM switch based on a hierar chical-cell-resequencing (HCR) mechanism and high-speed WDM interconnection and reports on its feasibility study. In a multi-stage ATM switch, cell-ba sed routing is effective to make the switch non-blocking, because all traff ic is randomly distributed over intermediate switching stages. But due to t he multi-path conditions, cells may arrive out of sequence at the output of the switching fabric. Therefore, resequencing must be performed either at each output of the final switching stage or at the output of each switching stage. The basic HCR switch performs cell resequencing in a hierarchical m anner when switching cells from an input-lines to a output-line. As a resul t, the cell sequence in each output of the basic HCR switch is recovered. A multi-stage HCR switch is constructed by interconnecting the input-lines a nd output-lines of these basic HCR switches in a hierarchical manner. There fore, the cell sequence in each final output of the switching fabric is con served in a hierarchical manner. In this way, cell-based routing becomes po ssible and a multi-stage ATM switch with the HCR mechanism can achieve 100% throughput without any internal speedup techniques. Because a large-capaci ty multi-stage HCR switch needs a huge number of high-speed signal intercon nections, a breakthrough in compact optical interconnection technology is r equired. Therefore, this paper proposes a WDM interconnection system with a n optical router arrayed waveguide filter (AWGF) that interconnects high-sp eed switch elements effectively and reports its feasibility study. In this architecture, each switch element is addressed by a unique wavelength. As a result, a switch in a previous stage can transmit a cell to any switch in the next stage by only selecting its cell transmission wavelength. To make this system feasible, we developed a wide-channel-spacing optical router AW GF and compact 10-Gbit/s optical transmitter and receiver modules with a co mpact high-power electroabsorption distributed feedback (EA-DFB) laser and a new bit decision circuit. Using these modules, we confirmed stable operat ion of the WDM interconnection. This switch architecture and WDM interconne ction system should enable the development of highspeed ATM switching syste ms that can achieve throughput of over 1 Tbit/s.