A barrier to delivering improvements in network bandwidth and latency to users is the network interface (NI), which connects a network to the host computer that runs the network software. An NI includes hardware that exposes an internal interface-such as device registers-to a host processor. A key problem with most current NIs is that their internal interface is similar to that of a disk's interface. Because of such limitations, current NIs will not be adequate for use with newer, high-performance networks and host computers. High-performance local area networks have advanced so far that some view them as a new class of networks called system area networks (SANs). Emerging SANs deliver bandwidths of 10 Gbps or more and latencies of tens of nanoseconds-two to four orders of magnitude better than that delivered by most current LANs. New hosts demand much higher performance. If NIs do not adapt to these changes they will become a barrier to improving network performance. To solve this problem, future NIs should appear to their hosts more like memory than disk interfaces. The authors argue that treating NI accesses like memory accesses is justified by the importance of network performance to future computers.