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Communication nodes are typically composed of multiple subsystems,each performing designated functions such as LAN interface, routing,format conversion, and high-level applications , etc.. Multiple subsystems are tightly coupled together to achieve the aggregated system functions and objectives by exchanging data and controls. Conventional backplane buses are uneffective means for the interconnection of multiple subsystems in broadband communication nodes,such as local ATM switches and super-hubs in Local Area Networks(LANs), because of the bandwidth inadequacy and physical distance constraint. The Multi-subsystem Interconnect(MSI)is intended as a scalable platform to facilitate the physical coupling and information exchange among multiple subsystems. The MSI is based on the fast-packet switching. Implemented on backplanes, it provides virtual channels for switching of level-2 information in sybsystems' memories , which are sent in 53 bytes packets by the MSI in hardware. The core of the MSI consists of a switching fabric and its control. The structure of the switching fabric provides multiple paths into each destination. Multi-cast is the inherent property of the fabric. Routing controls of packets are skewed to the switching fabric control one packet-time ahead. This pipe-line approach time constraint in performing any conflict resolutions,resulting simple logic design of the switching fabric control. The MSI subsystems will be highly reusable, in addition to having overhead-free communication and flexible physical interconnection capabilities. The MSI applications include local ATM switches, LAN superhubs, high performance bridges/ routers, and broadband bandwidth managers.
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