课程文献中心 更多>>

摘要： A new $14 million National Science Foundation (NSF) grant to upgrade a data communication network for scientific research will improve the speed of the network by more than an order of magnitude. The 5-year grant has been awarded to MERIT, Inc., a consortium of Michigan universities that will manage the network, which is called NSFNET. The network now transmits information at 56,000 bits per second (bps). With computer hardware and software contributed by IBM and fiber optics data transfer lines donated by MCI Communications, the upgraded network will be able to send and receive information at 1.5 million bps, the equivalent of about 50 single-spaced typewritten pages every second.

关键词： High-speed Networking   NSFnet   ARPANET   BITNET  

摘要： The NSFNET backbone network is being decommissioned in favor of a new backbone. The new backbone, which will become operational in July, will be managed by Merit Inc. of Ann Arbor, Michigan, in partnership with IBM and MCI. MCI is supplying circuits and circuit-switching equipment to connect the thirteen nodes;packet switches and associated monitoring and control equipment at each node, together with information and operations center mainframes installed at Merit, are being furnished by IBM. The NSFNET backbone now operating at 56 kbit/s, may enjoy a nearly three order of mganitude increase within the next five years.

关键词： 光通信   光突发交换   JET协议   竞争   波长变换器   optical communication   optical burst switching   NSFNet   contention   wavelength converter  

摘要： 介绍了光突发交换原理及波长变换技术.模拟了基于美国国家科学基金网络模型的光突发交换.数据源选用具有自相似性的突发性数据源,采用JET(Just-enough-time)信令协议,使用LAUC-VF数据信道调度算法.为减小竞争的发生,在网络中加入波长变换器.对带波长变换器和不带波长变换器的网络的性能进行了模拟,并对结果进行了分析.关键词

摘要： This study has developed a method to create an, to a big extent, automated testing system for NMP (Networked Music Performance) communication over LAN and WAN to be able to benchmark the UDP streaming engine JackTrip using a client-server model. The method is not locked into using JackTrip only, it could be used to do experiments with other engines too. The study tried to answer the question if latency correlates to amount of correctly aligned audio, and to what extent the audio is correctly aligned in respect to tolerated latency (based on earlier research) when at least two musicians remote-conducting musical pieces together. There were 13 different buffer settings tested, which used no redundancy and redundancy of 2, and which were sent through 4 different LAN/WAN-scenarios. A big dataset was produced, with about 82 minutes’ worth of audio per test. To post-process the data a phase cancelling method was used to measure correctly aligned audio, while the latency was measured by counting the number of samples from the start of each audio file to the first sample that were not null or not under a certain threshold. The results showed clear correlations of buffer sizes impact of latency and amount of correctly audio sent over the network. If the buffer sizes are greater, it will produce higher latency and increase the amount of correctly aligned audio, and on the opposite side, if using less buffer, it will produce lower latencies and less correctly aligned amount of audio. The study also showed that there was very little impact of using higher redundancies, both regarding latency and amount of correctly audio. When analysing the amount of correct data when respecting the tolerated level of latency, the study showed a support for correctly aligned amount of streamed audio up to 65% when using JackTrip. Den här studien har utvecklat en metod för att skapa ett, till stor del, automatiserat testsystem för NMP-kommunikation (Networked Music Performance) över LAN och WAN

摘要： This dissertation extends cooperative caching systems in three new directions: (1) I study the performance tradeoffs of using load balancing techniques to reduce the contention of remote page requests at memory servers, (2) I develop a novel combined prefetching and cooperative caching system to further reduce disk stall time for I/O-bound applications, and (3) I explore the effectiveness of using cooperative caching techniques among World Wide Web proxy caches at large-scale client populations. I use analytic, simulation, and measurement techniques to explore the performance of these new directions in cooperative caching ***, I develop an analytic queueing network model to evaluate the effectiveness of load balancing memory requests, and then use trace-driven simulation to study the potential harm of deviating from the replacement policy when balancing load. I find that deviating from the strict replacement policy does not significantly degrade overall application performance. Based upon these results, I conclude that cooperative caching systems can benefit considerably from load balancing requests with little harm from suboptimal replacement ***, I present the design of a combined cooperative prefetching and caching algorithm and its implementation in a prototype system called Prefetching Global Memory System (PGMS). I measure the performance of the PGMS implementation on a workstation cluster using both synthetic and real application benchmarks and conclude that, by using available global memory, disk, and CPU resources, cooperative prefetching and caching can obtain significant speedups for I/O-bound ***, I introduce a novel analytic model of Web accesses to explore the effectiveness of cooperative caching among World Wide Web proxies. This model evaluates the steady-state performance of proxy caches based upon server, object popularity, and document modification distributions. I use the model to evaluate cooperative Web proxy

摘要： Cites the World Wide Web's move to the top of the NSFnet's monthly Internet traffic statistics in March 1995.