Group Key Management

This report describes an architecture and implementation for doing group key management over a data communications network. The architecture describes a protocol for establishing a shared encryption key among an authenticated and authorized collection of network entities. Group access requires one or more authorization certificates. The implementation includes a simple public key and certificate infrastructure. Multicast is used for some of the key management messages. An application programming interface multiplexes key management and user application messages. An implementation using the new IP security protocols is postulated. The architecture is compared with other group key management proposals, and the performance and the limitations of the implementation are described. - v - 1. Introduction The Internet and private intranets are increasingly being used for business, government, and military communication. Information flowing over these networks often needs to be authenticated..

Message-Passing Performance of Various Computers

This report compares the performance of different computer systems for basic message passing. Latency and bandwidth are measured on Convex, Cray, IBM, Intel, KSR, Meiko, nCUBE, NEC, SGI, and TMC multiprocessors. Communication performance is contrasted with the computational power of each system. The comparison includes both shared and distributed memory computers as well as networked workstation clusters. 1 Introduction and Motivation 1.1 The Rise of the Microprocessor The past decade has been one of the most exciting periods in computer development that the world has ever experienced. Performance improvements, in particular, have been dramatic; and that trend promises to continue for the next several years. In particular, microprocessor technology has changed rapidly. Microprocessors have become smaller, denser, and more powerful. Indeed, microprocessors have made such progress that, if cars had made equal progress since the day they were invented, we would now be able to buy a car..

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A Tcp-Over-Udp Test Harness

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Measuring end-to-end bandwidth with Iperf using Web100

End-to-end bandwidth estimation tools like Iperf though fairly accurate are intrusive. In this paper, we describe how with an instrumented TCP stack (Web100), we can estimate the end-to-end bandwidth accurately, while consuming significantly less network bandwidth and time. We modified Iperf to use Web100 to detect the end of slow-start and estimate the end-toend bandwidth by measuring the amount of data sent for a short period (1 second) after the slow-start, when the TCP throughput is relatively stable. We obtained bandwidth estimates di#ering by less than 10% when compared to running Iperf for 20 seconds, and savings in bandwidth estimation time of up to 94% and savings in network tra#c of up to 92%

A TCP Tuning Daemon

Many high performance distributed applications require high network throughput but are able to achieve only a small fraction of the available bandwidth. A common cause of this problem is improperly tuned network settings. Tuning techniques, such as setting the correct TCP buffers and using parallel streams, are well known in the networking community, but outside the networking community they are infrequently applied. In this paper, we describe a tuning daemon that uses TCP instrumentation data from the Unix kernel to transparently tune TCP parameters for specified individual flows over designated paths. No modifications are required to the application, and the user does not need to understand network or TCP characteristics