共查询到19条相似文献,搜索用时 125 毫秒
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目前需要高速查找的电子系统,如交换机,路由器等,对查找的要求是兆次/秒。显然,不使用硬件加速算法,现有技术是无法满足需求的。本文设计实现了一种高速,利于硬件实现的HASH算法,给出了算法结构和算法性能评估。本算法可广泛应用于各种需要高速查找的系统中。1Hash算法介绍Hash算法是一种应用很广泛的计算机算法。其核心是对Hash函数的设计和实现。Hash function是算法的公 相似文献
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P2P技术的应用在现代网络系统中越来越普及,而云计算的出现给IT界带来了全新的挑战,因此,针对目前网络的发展现状,对P2P技术和云计算技术进行研究,提出了一种云计算环境中的P2P网络模型,这是云计算技术与P2P技术的一种结合。通过对使用P2P技术的网络中节点的处理能力、拥有的资源量、占据的带宽大小等进行评估,得出网络中各节点的层次结构并形成Hash环,然后利用一致性Hash算法在系统中对资源进行快速搜索。利用这种方法,由于每个节点只需要更新少量的信息就可以完成查询路由,从而实现了网络中资源的快速定位,提高了网络资源搜索的效率。 相似文献
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Hash函数的设计中,不仅要求Hash算法具有较好的混乱和扩散性、弱碰撞性,而且要求算法实现的高速性。提出了一种基于规则90细胞自动机的Hash函数方法,采用具有二叉树型状态转移的规则90细胞自动机作为Hash函数方法的迭代函数。实验与分析表明,这种构造方法在具有一般Hash函数较好混乱和扩散性、较安全的碰撞性,同时由于细胞自动机结构内在适合于VLSI的结构和并行的信息处理机制而具有其他Hash方法无法比拟的速度优势。 相似文献
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JAVA提供了对一整套对文件进行操作与管理的工具。其中主要有File类和RandomAccessFile类。File类提供了一套独立于操作系统的成员函数,这些成员函数可以使用户访问文件系统中的文件与目录的信息。这种特性使JAVA具有良好的可移植性(在UNIX系统中,文件与目录可同等访问)。通常,可以用以下三种构造函数来产生 相似文献
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城域以太网业务对终端设计中的多播机制实现提出了新的挑战.在阐述了以太网多播机制原理的基础上,重点分析了多播机制实现的不同方式,并给出了基于Hash过滤器的多播过滤机制实现原理.基于Hash过滤器的多播分组过滤机制已经被成功地应用于城域以太网的终端设计之中. 相似文献
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This paper analyzes user input to an X.500-based white pages directory service. The motivation for this study is that we can only optimize querying algorithms if we know what sort of queries people make. For example, do people mostly enter forenames and surnames, or surnames only; do people usually enter long organization names or sets of initials; do users enter the two-letter country codes. An area of key interest is how closely the names in users' queries correspond to directory names, as this helps us to determine the types of operation we need to resolve queries. The analysis is both for typed input, where the user is prompted for a set of name components, and also for input in the user-friendly name (UFN) format. We see that the free format of UFN's makes it much harder for users to frame queries which are likely to be successful. We see that while there is poor correspondence between user input and directory distinguished names, much of the user input can be matched exactly with names in the directory, due to the use of alternative names. A number of suggestions are made for transforming user input to increase the chances of finding the target entries 相似文献
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FTP是普遍使用的一种文件传输协议.网络中存在大量的FTP连接,因此IPv4-IPv6的转换网关必须支持大容量的FTP连接.FTP表中的FTP条目数量庞大,所以必须设计一个能够快速查找定位的大容量FTP表.基于上述考虑,设计中使用哈希算法,实现对FTP表的快速查找. 相似文献
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为进一步提高聚合位向量(ABV)算法分类数据包的速度,该文提出一种面向连接的改进ABV(IABV)算法。该算法利用同一连接包分类查找规则相对一致的特点,建立哈希表-规则库两级优化查找结构,首先通过哈希表查找包分类规则,若未命中继续从规则库中查找。利用连接时效性特点设计哈希表冲突处理机制,根据表项最近命中时间判断是否进行覆写更新,避免规则累积导致查找时间增加;其次对ABV算法各维度进行等分处理,为各等分区间建立数组索引,从而快速缩小向量查找范围,加快查找规则库速度;最后,将规则中前缀转化为范围降低辅助查找结构复杂度,以减少内存空间占用量并加快规则查找速度。实验结果表明,将规则中前缀转化为范围后能够有效提升算法性能,相同条件下IABV算法相比ABV算法时间性能有显著提高。 相似文献
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对低移动性、频繁搜索文件的无线Ad-Hoc网络,提出一种新型P2P文件共享系统,介绍一种将文件查找和路由功能统一起来形成跨层的方案。所有共享文件采用全分布哈希表,在无线网络拓扑结构建立的同时存储和保留位置信息以及路由信息.通过节点间的树形逻辑结构解决共享文件的定位查询和下载问题。 相似文献
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Xin Wang Schulzrinne H. Kandlur D. Verma D. 《Networking, IEEE/ACM Transactions on》2008,16(1):232-243
The Lightweight Directory Access Protocol (LDAP) is being used for an increasing number of distributed directory applications. We describe a tool to analyze the performance of LDAP directories, and study the performance of a LDAP directory under a variety of access patterns. In the experiments, we use a LDAP schema proposed for the administration of Service Level Specifications (SLSs) in a differentiated services network. Individual modules in the server and client code are instrumented to obtain a detailed profile of their contributions to the overall system latency and throughput. We first study the performance under our default experiment setup. We then study the importance of the factors in determining scalability, namely front-end versus back-end processes, CPU capability, and available memory. At high loads, the connection management latency increases sharply to dominate the response in most cases. The TCP Nagle algorithm is found to introduce a very large additional latency, and it appears beneficial to disable it in the LDAP server. The CPU capability is found to be significant in limiting the performance of the LDAP server, and for larger directories, which cannot be kept in memory, data transfer from the disk also plays a major role. The scaling of server performance with the number of directory entries is determined by the increase in back-end search latency, and scaling with directory entry size is limited by the front-end encoding of search results, and, for out-of-memory directories, by the disk access latency. We investigate different mechanisms to improve the server performance. 相似文献
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针对有效管理各种资源信息能便于检索和查询,并且可以保证网络信息安全。LDAP目录服务技术就是一种管理资源信息技术,同时它作为认证服务得到广泛应用。文中研究了LDAP认证实现原理,模拟了LDAP目录存储及认证过程,展示了LDAP的优势。通过实验,测试出影响LDAP认证性能的因素,并对其加以分析,进一步优化了LDAP认证。 相似文献
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Hash tables are one of the most commonly used data structures in computing applications. They are used for example to organize a data set such that searches can be performed efficiently. The data stored in a hash table is commonly stored in memory and can suffer errors. To ensure that data stored in a memory is not corrupted when it suffers errors, Error Correction Codes (ECCs) are commonly used. In this research note a scheme to efficiently implement ECCs for the entries stored in hash tables is presented. The main idea is to use an ECC as the hash function that is used to construct the table. This eliminates the need to store the parity bits for the entries in the memory as they are implicit in the hash table construction thus reducing the implementation cost. 相似文献