The Impact of a Zero-Scan Internet Checksumming Mechanism

This paper describes a "zero-scan" mechanism that reduces Internet checksumming overhead from a per-byte scan (or copy) cost, to a small and constant per-message cost. Unlike previous techniques, this mechanism requires no message buffering within the source. This will allow Internet transport protocols to achieve transfer latencies comparable to specialized protocols implemented directly on high-speed LAN (link-layer) services. In addition, this mechanism is transparent to systems outside of the source LAN. Hence, this mechanism affords applications the portability of Internet protocols without sacrificing the high performance of specialized LAN transport protocols. The proposed zero-scan checksumming scheme eliminates the last requirement for an additional data copy/scan, beyond the scan required to transmit or receive from the network channel. If this checksumming mechanism is combined with zero-copy operating system mechanisms that provide low-overhead transfer across application a..

Internet Protocols for Network-Attached Peripherals

This paper presents our thesis that the advantages of the internet protocol framework make it the best choice for communications protocols to, and between, network-attached peripherals #NAPs#. Moreover, the IP suite is more appropriate than the specialized protocol stacks being developed for commercial NAPs. The bene#ts of using IP include support for heterogeneous network media, wide-area connectivity, and reduced research and development e#ort. We examine the issues for use of the internet protocols #TCP#UDP#IP# for NAPs, address commonly held concerns regarding its performance, and describe the Netstation project's prototype implementations of IP peripherals

Derived Virtual Devices: A Secure Distributed File System Mechanism

This paper presents the design of ####################### (DVDs). DVDs are the mechanism used by the Netstation Project to provide secure shared access to network-attached peripherals distributed in an untrusted network environment. DVDs improve Input/Output efficiency by allowing user processes to perform I/O operations directly from devices without intermediate transfer through the controlling operating system kernel. The security enforced at the device through the DVD mechanism includes resource boundary checking, user authentication, and restricted operations, e.g., read-only access. To illustrate the application of DVDs, we present the interactions between a network-attached disk and a file system designed to exploit the DVD abstraction. We further discuss third-party transfer as a mechanism intended to provide for efficient data transfer in a typical NAP environment. We show how DVDs facilitate third-party transfer, and provide the security required in a more open network environment