Network fabrics with Gigabit per second (Gbps) bandwidths are available today, but these bandwidths are not yet available to applications. The difficulties lie in the hardware and software architecture through which application data travels between the network and host memory. The hardware portion of the architecture is often called a host interface and the remainder of the protocol stack is implemented in host software. In this paper, we outline a variety of approaches to the architecture of

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... ch systems, examine several design points, and study one example in detail. The detailed example, an ATM Host Interface and Operating System support built at the University of Pennsylvania, illustrates design tradeoffs for hardware and software, and some of the implications of these tradeoffs on applications performance.