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Freescale公司 《世界电子元器件》2007,(4):94-98
以太网供电(PoE)定义以太网供电(PoE,Power over Ethernet)是指通过现有的网络电缆在传输数据的同时为处于不同网络位置的低功率应用设备提供电源,它可以保证在CAT5/CAT5e/CAT6等电缆上安全提供48V电压、15W 相似文献
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付铮 《电信工程技术与标准化》2003,(1):63-65
通信领域受控于两种截然不同的技术,即用于局域网(LAN)中内部业务通信的以太网及广域网(WAN)中的SONET/SDH。在网络可靠性至关重要的企业环境中,以太网已经成为普遍使用物数据网络协议,以太网具有简单,高效和可靠性极高等优点,适用于LAN环境,本介绍了虚级联和通用成帧规程。 相似文献
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光纤与以太网的媒体桥接转换器使两种介质方便的连接在一起,为当今视频流和大型存储数据的传输提供了一个高速可靠、传输距离长、成本合算的解决方案。利用功能强大的KS8995集成交换芯片,设计外围辅助电路,设置交换芯片各功能管脚的电平,添加直流偏置和阻抗匹配电路,实现以硬件为基础的10/100、双工/单工、流控制及自动协商系统,完成10/100Base-TX与100Base-FX间的顺利转换。关键词 相似文献
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报文对间隔及报文单向延迟的变化可以反映报文发送速率与可用带宽的大小关系,根据这个规律本文提出了一种基于应用需求的网络路径可用带宽测量策略COPP.COPP发送多组发送速率不断增大的报文对序列,并从每组序列中求出所有成为转换点的报文对,然后根据这些报文对所受干扰的不同程度赋以它们不同的权重,从而得到路径可用带宽.COPP可根据具体应用不同的带宽需求动态决定测量范围,仿真实验研究了测量中探测报文大小的选择,并通过与Pathload等其它带宽测量方法的比较验证了COPP具有低开销、高精度、平稳性好且对网络状态变化敏感等优点. 相似文献
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Programmable network interfaces can provide network servers with a flexible interface to high-bandwidth Ethernet links, but they face critical software and architectural challenges. This article explores architectural and software support for an efficient programmable 10 Gigabit Ethernet controller. The design is then extended to support a self-securing Gigabit Ethernet controller that performs intrusion detection on all network data frames. Both raw performance and security require high- bitrate frame data transfer, low-latency metadata access, and intensive computational capacity while still operating under the area, cost, and power budget of a peripheral device. These goals are achieved using a combination of parallel lightweight processing cores, an explicitly-partitioned memory system, and dedicated hardware assists. The firmware on the network interface is designed to utilize these resources efficiently by exploiting frame-level, flow-level, and task-level concurrency. 相似文献
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吴洁 《电子产品可靠性与环境试验》2010,28(3):37-42
电压波动和闪烁测量是电子电器产品EMC测量和电能质量检测中的一个重要项目,但电压波动和闪烁测量仪的校验一直是一个难题,多数校准实验室并不具备相应的能力,行业中也普遍忽视该仪器的校准与验证。依据实验室量值溯源的要求,分析电压波动和闪烁测量项目中需要校准的参数及其准确度要求,介绍了电压波动和闪烁测量仪的校准方法,以及实验室如何进行验证的方法。 相似文献
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基于Ethemet over E1的原理,结合通用嵌入式芯片的功能特点,辅以现场可编程器件,介绍了Ethemet over E1网桥系统中核心部分的设计,包括网桥的系统统构、HDLC接口模块的嵌入式程序设计和E1接口电路的FPGA设计.E1接口电路分为数据接收、时隙选择、时钟产生、数据发送四大模块,用FPGA逐一实现.有关设计经过多次软硬件联合仿真验证后,在基于嵌入式系统的网桥项目中通过了板级的功能测试和验证,取得到了较好的效果. 相似文献
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基于L5A4266 ChipBridge芯片远程以太网桥的设计与实现 总被引:1,自引:0,他引:1
分析了基于L5A4266 ChipBridge芯片的远程以太网桥系统总体设计思路,研究了该远程以太网桥备功能模块,给出了该系统的硬件设计实现方案。 相似文献
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系统地介绍了以太网的基本概念,介质接入控制和物理层标准规范,以太网信号的帧结构,网络硬件设备,网络组成及主要的性能,以及以太网信号在PDH,SDH/SONET中的传输等等,本部分为介质接入控制方法和物理层性能的标准规范,在介质接入控制方法方面介绍耻半双工和全双工以太网两种工作模式,在物理层性能标准规范方面分别介绍了1Mbit/s,10Mbit/s,100Mbit/s,1000Mbit/s以太网的物理层性能标准规范。 相似文献
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Ferrari P. Flammini A. Marioli D. Taroni A. 《Industrial Informatics, IEEE Transactions on》2008,4(1):16-25
Ethernet technology is widely used in real-time industrial automation. Thanks to real-time Ethernet (RTE) protocols, defined in IEC61784-2 standard, new top-performance automation solutions can be created. Such systems may have communication cycle time down to tens of mus and cycle jitter less than 1 mus, making network testing and debugging very critical. Existing network and protocol analyzers can perform detailed local analysis, but characterization of high-performance RTE systems requires measurement of transmission delays and these instruments cannot be adequately synchronized among them to realize a distributed measurement network. This paper introduces a new low-cost distributed measurement instrument to measure timing characteristics of RTE nodes (end-to-end delays, synchronization, etc.). The proposed instrument has multiple FPGA-based probes that allow for simultaneous/synchronized logging on different place of the target RTE network. A PC-based "monitor station" stores all the data, ready for further elaboration. Architecture details are discussed, a prototype has been realized, and some experimental results are presented. For instance, synchronization accuracy between probes is below 100 ns. 相似文献
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This paper addresses top-down end-to-end user-oriented performance requirements pertaining primarily to voice and digital data services. The discussion of requirements for voice parameters accounts for the performance of existing analog and mixed analog/digital networks, as well as the likely effects on performance of short, medium, and long term evolution toward the ultimate all digital ISDN. The requirements for digital data parameters necessarily reflect an evolutionary process which is less consistent than for voice, and therefore these requirements are less definitive in nature. The discussions of voice and digital data performance apply largely to a wide variety of appropriate network designs, transmission schemes, and switching architectures. Both traditional parameters, as well as contemporary parameters associated with new and evolving systems, are considered. The emphasis is on the performance of nation-wide public and private networks, but the paper also considers the constraints of international connections. 相似文献