Arista-Architecting Low Latency Cloud Networks whitepaper-chinese

合集下载

省级卫星中心遥感数据管理服务平台建设实践

收稿日期：2021-01-10。

项目来源：湖北省自然资源厅科技项目（ZRZY2020KJ09）。

省级卫星中心遥感数据管理服务平台建设实践周长雯1,闵天1,祁信舒1,张霞2（1.湖北省航测遥感院，湖北武汉430074；2.湖北省测绘工程院，湖北武汉430074）摘要：以省级卫星中心遥感数据综合管理服务平台建设为例，设计了基于Web 服务器、PostgreSQL 数据库、C/S 架构、B/S架构等技术的遥感数据管理方法。

通过建设实践解决大规模遥感数据和信息产品共享中的多项关键技术，消除了目前空间数据分散和信息孤岛现象，提高了遥感数据查询、获取的准确性和时效性，实现了信息资源共享和高效服务。

省级遥感数据管理服务平台的构建，为自然资源管理部门及社会公众提供了及时有效的动态监测信息和科学决策，可进一步推广应用在市县卫星应用技术中心节点的建设中。

关键词：卫星中心；遥感数据；平台建设；PostgreSQL 数据库；共享服务中图分类号：P237文献标志码：B文章编号：1672-4623（2022）06-0135-04Remote Sensing Data Management Service Platform Construction and Practice forProvincial Satellite CenterZHOU Changwen 1,MIN Tian 1,QI Xinshu 1,ZHANG Xia 2（1.Hubei Institute of Photogrammetry and Remote Sensing,Wuhan 430074,China;2.Hubei Institute of Surveying and Mapping,Wuhan 430074,China ）Abstract:Taking the provincial satellite center remote sensing data integrated management service platform construction as an example,we de-signed remote sensing data management methods based on Web server,PostgreSQL database,C/S architecture,B/S architecture and other tech-nologies.Through construction and practice to solve a few key technologies in the sharing of large-scale remote sensing data and information products,eliminate the current spatial data dispersion and information island phenomenon,and improve the accuracy and timeliness of remote sensing data query and acquisition,we achieved information resource sharing and efficient service.The provincial remote sensing data manage-ment service platform construction provides the natural resource management department and public with timely and effective dynamic monitor-ing information and scientific decision-making,which can be further promoted and applied in city and county satellite application technology cen-ter node construction.Key words:satellite center,remote sensing data,platform construction,PostgreSQL database,shared services随着我国“高分辨对地观测”重大专项和“空间基础设施”的实施，遥感对地观测获取能力逐步提升，推送的卫星对地观测数据量呈较大的增长趋势。

高考英语《语法填空+阅读理解+应用文写作》真题含答案

高考英语《语法填空＋阅读理解＋应用文写作》真题含答案Ⅰ.语法填空5th World Media Summit, and other significant events, once again highlighting its role as1.________ window for the world to comprehend China's highquality development. So,2.________ Guangzhou? Let's find out.3．________ (gain) a deeper understanding of China, one must experience its history and culture. With a history of over 2，000 years and a rich cultural heritage, Guangzhou offers a variety of historical and cultural 4.________ (treasure). In this city, you can sip (呷) a cup of coffee while watching Cantonese opera in Yongqingfang or taste Cantonese dim sum (点心) while gazing at Westernstyle architecture on Shamian Island.The economy is another crucial aspect in understanding China. In recent years, Guangzhou has 5.________ (active) participated in the Belt and Road international cooperation, gradually 6.________ (establish) an allround, multilevel, and wideranging pattern of openingup. As a thousandyearold commercial city known for the Canton Fair, Guangzhou has drawn 7.________ (globe) attention with its open genes and prosperous economy.Connecting with the world also requires a highly 8.________ (develop) transportation network. Guangzhou has constructed a modern threedimensional transportation system that links airports, seaports, railway ports, and digital ports, providing easy access 9.________ both domestic and foreign participants.Guangzhou's openness, inclusiveness, vitality, and innovative spirit make it an ideal choice for hosting international events, which, in turn, 10.________ (help) the economic and social development of the city.【语篇解读】本文是一篇说明文。

stable difusion lora列举

stable difusion lora列举"Stable Diffusion of LoRa: A Multitude of Possibilities"Introduction to LoRa and Its Stable DiffusionIn recent years, the Internet of Things (IoT) has gained significant attention, with the promise of creating a network of connected devices that can enhance our daily lives. However, one of the challenges faced in building a robust IoT infrastructure is finding a stable and efficient communication protocol. This is where LoRa (Long Range) technology comes into play. In this article, we will explore the stable diffusion of LoRa, discussing its benefits, applications, and the steps involved in implementing it.Understanding LoRaLoRa is a wireless communication technology that enableslong-range and low-power communication for the IoT. Developed by Semtech, it is a popular choice due to its ability to provide reliable communication over a wide range of distances while consuming minimal power. LoRa operates in the unlicensed Industrial, Scientific, and Medical (ISM) bands, which allow forseamless deployment without needing to obtain additional licenses.Benefits of Using LoRa1. Long Range: One of the key advantages of LoRa technology is its ability to transmit and receive data over long distances, ranging from a few kilometers in urban areas to tens of kilometers in rural areas. This extended range makes it ideal for applications that require communication over large geographical areas.2. Low Power Consumption: LoRa devices are designed to consume minimal power, which makes them suitable for battery-operated IoT devices. By using power-efficient modulation schemes, LoRa devices can operate for extended periods without the need for frequent battery replacements.3. Low Cost: LoRa technology offers an affordable solution for IoT deployments. With its long-range capabilities, fewer base stations are required to cover a given area, reducing infrastructure costs. Additionally, LoRa devices are relatively inexpensive and readily available in the market.4. High Scalability: LoRa supports a large number of devices simultaneously, making it suitable for applications with a high density of IoT devices. This scalability ensures that the network can handle an increasing number of connected devices without compromising on performance.Applications of LoRa1. Smart Agriculture: LoRa technology finds extensive application in the agricultural sector, enabling farmers to monitor and manage their crops more efficiently. With LoRa-enabled sensors placed throughout the farmland, farmers can collect real-time data on soil moisture, temperature, and humidity, allowing them to optimize irrigation and fertilizer usage.2. Asset Tracking: LoRa's long-range capabilities make it an ideal solution for tracking and monitoring assets over large areas. Companies can utilize LoRa-enabled trackers to monitor the location and condition of valuable assets such as shipping containers, vehicles, and equipment, ensuring their safety and enabling efficient asset management.3. Smart Cities: LoRa plays a crucial role in building smart cities by enabling various smart applications. From smart parking and waste management systems to environmental monitoring and energy management, LoRa technology provides a reliable andcost-effective communication infrastructure required for these applications to operate seamlessly.4. Industrial Automation: With its low power consumption and long-range capabilities, LoRa technology offers significant advantages in industrial automation. It enables real-time monitoring of machines, predictive maintenance, and remote control, leading to improved efficiency, reduced downtime, and cost savings.Implementing LoRa in IoT ProjectsImplementing LoRa in an IoT project involves several key steps:1. Network Planning: Determine the coverage area and required number of LoRa gateways to provide sufficient coverage. Address potential interference sources and ensure optimal spacing betweengateways for reliable communication.2. Device Selection: Choose LoRa-enabled devices or sensors suitable for the application requirements. Consider factors such as power consumption, range, and data transfer rate when selecting devices.3. Gateway Deployment: Install LoRa gateways strategically to ensure adequate coverage. Factors such as terrain, building structures, and interference sources should be considered when placing gateways for optimal signal transmission.4. Network Configuration: Configure the LoRa network by ensuring gateways, devices, and sensors are properly registered and associated with their respective network servers. Set up secure network connections to protect data integrity.5. Application Development: Develop or integrate IoT applications to interface with the LoRa network server. This involves designing user interfaces, implementing data analytics, and integrating the collected data into existing systems or platforms.ConclusionLoRa technology offers stable diffusion for IoT applications, with its long-range capabilities, low power consumption, scalability, and cost-effectiveness. Its applications in smart agriculture, asset tracking, smart cities, and industrial automation are just a glimpse of the possibilities that LoRa technology presents. By following the steps involved in implementing LoRa, IoT projects can realize the full potential of this reliable and efficient communication protocol.。

IMOS inside冲击产业价值链

传统合作手段不 “ 力” 给
事实上，以往整个安防产业链中厂
商的增值合作开发业务，Ｉ和Ｔ产业相比
起来，显得较为 “ 落后 ” 一些。直以来，一
应用系统围绕前端设备的ＳＫ开发为主Ｄ的模、各不相关的单个系统，而是彼此之间联系紧密、大量数据相互交互的融
合型应用。
集成商（Ｖ）过厂商提供的设备ＳＩ通ＳＤＫ
接口，针对客户的需求进行定制性开发
工作，面向客户的同时开发基础管理平台和行业应用平台，并整合存储设备。
展的重要因素。
杂的大型监控项目，这种方式可谓难负众望。乏统一的平台级接口、统管理缺系
放性著称的多媒体解决方安案提供商Ｈ３Ｃ，展示了这一给安防行业发展带来
能力弱、开发工作量大、异构屏蔽ｌ生差、
国内安防产业的局面是厂商数量多、规
５４中国信息化Ｊ０１２．０２０１２
种异构组件并构建自己的业务系统。ＩＳｉｓｅ生的背景十分明确。ＭＯｎｉ诞ｄ按照闫夏卿的话说，就是要借取Ｉ行业Ｔ的经验，用中间件平台的思路，专注采让业务的厂商，面对各种不同摄像机等硬
发，改变这种合作模式势在必行。 ” 事实上，这种改变也是顺应用户和市场的要求。整个安防监控行业高速发在

Palo Alto Networks与Arista Networks网络安全集成技术简介说明书

Palo Alto Networks andArista NetworksNetwork-based security integration providing dynamic automated deploy-ment, deep visibility, and robust security for physical and virtual workloadsThe ChallengeData centers have increasingly virtualized and partitioned their networks, becoming more dynamic while accommo-dating on-the-fly deployment of new applications within shared private, public, and hybrid clouds. Furthermore, the threat landscape is changing. Hackers are finding new ways to breach the data center with an influx of new vulnerabil-ities and threats. Enterprises are faced with the c omplexity of i mplementing agile security architectures to address a h ybrid environment of microservices, virtual workloads, and legacy applications to protect critical assets from mod-ern threats. This includes securing traffic between modern application clusters and bare metal workloads. SecOps is challenged to maintain control over traffic and detect any compromised assets within the data center.Arista Networks Macro-Segmentation Service Arista Networks Macro-Segmentation Service® (MSS®) c apability for CloudVision® allows a variety of platforms, such as next-generation firewalls, to be deployed a utomatically for specific workloads and workflows across any network t opology, including Layer 2, Layer 3, and overlay network vir-tualization frameworks.MSS is a capability within Arista CloudVision that addresses a growing gap in security deployment for hybrid data centers. It extends the concept of fine-grained intra-hypervisor secu-rity for virtual machines (VMs) to the rest of the data center by enabling dynamic insertion of services for physical devices and non-virtualized devices. It is specifically aimed at phys-ical-to-physical and physical-to-virtual workloads, with complete flexibility on the placement of service devices and workloads.MSS components include:• Arista leaf-spine switch fabric• Arista CloudVision• Vendor firewall attached to a service leaf switch. Firewalls can be attached in high availability configuration (active-standby or active-active) as well.Palo Alto NetworksPalo Alto Networks Next-Generation Firewalls offer a preven-tion-focused architecture that is easy to deploy and operate. Automation reduces manual effort so your security teams can replace disconnected tools with tightly integrated innovations, focus on what matters, and enforce consistent protection e verywhere.Next-Generation Firewalls inspect all traffic, including all a pplications, threats, and content, and tie that traffic to the user, regardless of location or device type. The user, appli-cation, and content—the elements that run your business— become integral components of your enterprise security policy. As a result, you can align security with your business policies as well as write rules that are easy to understand and maintain. Palo Alto Networks and Arista MSSBy integrating with native APIs provided by Next-Generation Firewalls in the data center (PA-3200 Series, PA-5200 Series, and PA-7000 Series) and Palo Alto Networks Panorama™ net-work security management, MSS learns the security policies, identifies the workloads the firewall needs to inspect, and takes action. Upon identification, MSS can now steer relevant traffic to the firewall, inserting the firewall in the path of workload flows.The automation capabilities of Arista MSS operate in real time without any need for a network operator to engage the security administrator. Furthermore, there is no need for the network to be architected in a manner specific to a particular workload. This flexibility is crucial to the successful deploy-ment of security in an enterprise private or hybrid cloud. With this new integration, Next-Generation Firewalls can create security policies from a central point and implement them across the network.Benefits of the Integration• Dynamic service insertion• Complete flexibility on locality of devices• No new frame formats or protocols required• Network security integration driven by automationPalo Alto Networks | Arista Networks | Tech Partner Brief13000 Tannery Way Santa Clara, CA 95054Ma i n: +1.408.753.4000Sales: +1.866.320.4788Support: +1.866.898.9087 © 2020 Palo Alto Networks, Inc. Palo Alto Networks is a registered t rademark of Palo Alto Networks. A list of our trademarks can be found at https:///company/trademarks.html. All other marks mentioned herein may be trademarks of their respective companies. palo-alto-networks-and-arista-networks-tpb-051920Use Case No. 2: Complete Flexibility on S ecurity Device Location Next-Generation Firewalls can be connected anywhere in the network on any switch. This allows larger data centers to centralize their security devices in a service rack and logically insert them in the path between any workloads on demand or based on a firewall policy. There are no restrictions or limita -tions on where security devices are physically attached withinFigure 1: Palo Alto Networks and Arista Networks integration architecture Use Case No. 1: Intelligent Inspection of East-West Traffic on DemandArista’s MSS does not try to “own security policy” or need to run a controller-of-controllers that understands every a pplication flow or interaction. Customers can define secu -rity policies within Panorama.Using the API plane, Arista CloudVision obtains the relevant rules from Panorama and programs the Arista switches to steer intercepted east-west workload traffic to Next-Gen -eration Firewalls for robust traffic and content inspection as well as policy enforcement. Security administrators now have the flexibility to add or remove policies to monitor traffic between workloads on demand, and they can profile traffic to proactively detect malware or denial-of-serviceattacks from within the enterprise.the fabric. Palo Alto Networks firewalls are discovered via Link Layer Discovery Protocol (LLDP). Likewise, devices to which services are targeted can be located anywhere in the network with no restrictions or limitations on physical e Case No. 3: Offload Traffic Inspection with Intelligent Security Policies In addition to redirecting traffic to the firewall, security admin -istrators can define rules within Panorama to offload predict -able traffic from the firewall. Arista MSS enforces these poli -cies on the switches. In a legacy architecture, all traffic would be steered to the firewall for processing, consuming bandwidth and CPU resources. This offloading function enables the fire -wall to provide high-performance deep packet inspection and intrusion prevention services for unknown traffic, reducing the risk of malware or threats gaining footholds.About AristaArista Networks pioneered software-driven, cognitive cloud networking for large-scale datacenter and campus environ -ments. Arista’s award-winning platforms, ranging in Ethernet speeds from 10 to 400 gigabits per second, redefine scalability, agility and resilience. Arista has shipped more than 20 million cloud networking ports worldwide with CloudVision and EOS, an advanced network operating system. Committed to open standards, Arista is a founding member of the 25/50G consor -tium. Arista Networks products are available worldwide direct-ly and through partners. Find out more at .About Palo Alto NetworksPalo Alto Networks, the global cybersecurity leader, is shaping the cloud-centric future with technology that is transforming the way people and organizations operate. Our mission is to be the cybersecurity partner of choice, protecting our digital way of life. We help address the world’s greatest security challenges with continuous innovation that seizes the latest breakthroughs in artificial intelligence, analytics, automation, and orches -tration. By delivering an integrated platform and empower -ing a growing ecosystem of partners, we are at the forefront of p rotecting tens of thousands of organizations across clouds, networks, and mobile devices. Our vision is a world where each day is safer and more secure than the one before. For more information, visit .。

阿科桑底——试问如果,建筑、生物与城市设计

阿科桑底——试问如果,建筑、生物与城市设计
杰夫·斯坦因;尚晋
【期刊名称】《世界建筑》
【年(卷),期】2017(000)004
【总页数】6页(P30-35)
【作者】杰夫·斯坦因;尚晋
【作者单位】亚利桑那州科桑底基金会
【正文语种】中文
【相关文献】
1.桑泰尼科自主品牌的光荣与梦想——桑泰尼科自主研发印后自动化设备之路 [J],
2.阿科桑底的风铃 [J], 周榕
3.重新想象建筑,倾斜现实评BAU建筑与城市设计事务所的建筑与城市设计 [J],
阿曼达·阿克曼迪;方群
4.绿色建筑——可持续发展之路——基于生物气候条件的绿色城市设计生态策略[J], 王建国;徐小东
5.未来生态城市的样本——阿科桑底 [J], 郭爽
因版权原因，仅展示原文概要，查看原文内容请购买。

没有搜索的搜索——专访Google首席搜索工程师阿米特·辛格哈尔

没有搜索的搜索——专访Google首席搜索工程师阿米特辛
格哈尔
张娅
【期刊名称】《商务周刊》
【年(卷),期】2010(000)013
【摘要】试想一下这样的场景：你身处一个陌生城市，街边的建筑吸引了你的注意，你认为它非常特别，但身边既没有导游，也没有携带旅游手册。

你用手机摄像头拍下这个建筑，上传到Google。

Google会扫描这个图像，确定它是什么，并把搜索结果发送给你。

参观完建筑，你决定美餐一顿。

再次打开手机，无需输入，通过GPS或手机发射塔，你就可以在Google的搜索框下看到一个蓝色小气泡和你所在的位置。

【总页数】2页(P90-91)
【作者】张娅
【作者单位】不详
【正文语种】中文
【中图分类】TP393.092
【相关文献】
1.Google学术搜索——科学引文搜索的利器 [J], 王兴华
2.专访Google图像搜索创始工程师 [J], 闫辉
3.桌面搜索软件超级试用 Google桌面搜索中文版和百度硬盘搜索 [J], 肖树平
4.搜索引擎google与百度研究与新兴搜索引擎改进 [J], 赵捷
5.你也能用GOOGLE成为搜索专家活用Google搜索密技 MP3、软件、图片、序列号……,搜个够!之一 [J], 大有
因版权原因，仅展示原文概要，查看原文内容请购买。

Asigra与Artisan Infrastructure携手共同扩展云数据备份服务

ｓｎ ’助力的私有、ｔｅ，ｏ）安全和专用区间内
对它ｔ自己的基于Ａｓｒ＇１］ｉａ的备份解决ｇ
方案进行评估和测试。Ａｓｒｉａ公司产品营销部的高级总ｇ监Ａｈｒａｇ表示：Ａｉａ与ＡｔａｓａｉＢ “ ｓｒｇｒｓｎｉ
备份。”
建了概念验证的可实施模式，以在一个由Ａｔａｆｓｕ￣ｅ的虚拟专用数ｒｓｎＩａｔｃｉｎｒ据中心平台（ＰＣ被称之为“ ｏｒｖＤ）（Ｃｍｅ－
ｔｔｒ和Ａｉｒ）合作使得Ｎｅｐｍｃｅｕｓａ的ｇｔｐＡ作为存储供应商成功地成为了进行云
选用Ａｓｒｉａ作为其云备份解决方案，ｇ
ｖＤＣ和ＮｅｐＰｔｐ存储，部署ＡｉａＡｓｒ助ｇ
力的云备份服务既快速又简单。Ａｒ．ｔｉ
Ｓ丘ｓｕｔｒ所有用户可随时获ｎｎａＩａ仃ｃｅ的ｕ取Ａｓｒ可实施解决方案模式。一ｉａ的ｇ
增值分销商（Ａ）供他们自己的云ＶＲ提
备份服务。该服务基于高效、灵活的Ｎｔｐ［储，有较大型托管公司的ｅＡｐ存］具竞争实力，更加高效。且
总部位于多伦多的Ａｉａ公司和ｓｒｇ
品。我们与创新公司（ＡｔａＩｆｓ如ｒｓｎｒ．ｉｎａ

1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。

Arista 构建低延迟云网络
前言：在云网络环境中，应用的响应时间至关重要。

随着数据中心迁移到下一代虚拟化弹性云架构，为确保应用永远在线、始终可用，高性能、灵活的云云网络成为必须。

在过去十年，对应用响应时间的要求越来越严苛（见图1），在一些情况下甚至提高了二到三个数量级。

除金融、教育/科研机构和Web 2.0公司之外，越来越多的垂直行业客户开始将快速的响应时间视为首要的业务要求之一，这其中包括多媒体公司（如从事视频后期制作、数字动画和广播业务的客户）、石油天然气生产商和医疗机构。

图1: 应用响应时间发展趋势
随着响应时间逐渐缩至几分之一秒，网络和计算延迟也必须同步降低。

因此，我们需要采取一种有效的架构方法，以便大幅度改进各种云应用的响应时间。

与以前部署针对性技术、甚至采用专有技术的做法相比，目前的关键要求是采用基于标准和广泛普及的基础设施架构来部署低延迟的云网络。

同时，由于延迟优化是在基础设施级别实施，这种优化必须适用于未来发展，以满足3到5年之内的延迟要求。

构建低延迟云网络
延迟敏感型工作负载的一个主要特点是它们采用分布式计算架构。

每个工作负载交易都将在计算节点之间产生大量交互，在某些情况下甚至涉及几千台机器和数据存储库，如图2所示。

举例来说：
l● 在算法交易中，机器在收到来自其他机器的市场数据后，将计算交易决策，并在另一组机器上开展交易。

l● 在HPC 中，几千个商用服务器汇集成一个集群，作为一个“超级计算机”执行操作，它与一个集群文件系统（如Lustre ）相连，以处理复杂的数学公式和模拟运算。

l● 在基于Web 的云应用中，工作负载在由几千个服务器组成的动态集群上运行，并使用多级处理机制，以筛选整理数拍字节（petabytes ）的数据。

相关例子包括Web 2.0和互联网搜索公司使用的应用，以及Hadoop 等新兴的开源计划。

Hadoop 为分布式计算(MapReduce)、分布式文件系统和分布式数据库提供了可扩展的可靠框架。

图2: 基于网络的单个工作负载的机器间交互：一个交易
响应时间
资本市场
高性能计算
以Web 为中心的分布式计算
时间
为显著改进系统级响应时间，必须最大限度缩小计算和网络延迟。

通常会选择最好的商用服务器，使其处理延时小到极限。

用户通常会选择配备密度更高、速度更快的多核心CPU ；更大、更快的内存/高速缓存和速度更快的外设连接服务器。

另一方面，在云网络中，必须通过平台级(fabric-wide)优化来实现传输延迟最小化。

具体来说，应在四个重要领域优化网络延迟： l● 降低每个网络节点的延迟
l● 减少从一级转至另一级所需穿越的网络节点的数量 l● 消除网络拥塞
l● 降低传输协议延迟
Arista 的优势：
Arista Networks 采取了一种体系架构方法来构建低延迟云网络。

利用Arista 的线速、无阻塞、超低延迟千兆/万兆以太网交换机以及可扩展的操作系统(EOS)，构建灵活的云网络，用于传输数据、多媒体、存储和计算流量。

采用Arista 的7xxx 系列交换机构建云网络具有以下优势： l● 从四个重要方面降低网络延迟（详见下文）；
l● 适应未来发展的网络基础设施，可满足当前和未来的延迟要求； l● 部署应用广泛且易于操作的标准以太网。

网络节点延迟:对于金融应用和HPC 等领域的超低延迟工作负载而言，缩短每一微秒的延迟都至关重要。

通过部署最佳的千兆/万兆以太网交换机，可将1500B 以太网帧的传输延迟缩短10微秒以上（如果使用9KB 巨型帧，延迟还可降低更多）。

此外，与传统的存储与转发设计相比，直通式交换架构还可将延迟缩短数十微秒。

Arista 推出的直通式架构高密度万兆交换机，可将交换延迟保持在0.6 - 1.2微秒之间（见图3）。

图3: Arista 直通式交换机相对于传统存储与转发交换机的延迟优势
网络跳数：典型的数据中心架构采用三层架构：即服务器接入层、分布层和核心交换层。

通常数据包在服务器机架之间传输时最终都要到达核心层。

在Arista 采用分支和主干交换机的双层拓扑中（见图4），由于数据包需要穿越的跳数减少，因此延迟也大为降低。

分布层
服务器接入层
(a) 存储与转发交换机的延迟
到服务器的
千兆以太网连接
延迟
总线
现有核心
主干层
分支层
(b) Arista 直通式交换机的延迟
延迟
传统的存储与转发设计
机架内部延迟：8us 机架间延迟：36us
(b) Arista 直通式设计
机架内部延迟：0.6us 机架间延迟：2.4us
图4: Arista 双层(分支与主干)拓扑的延迟低于传统的3层（接入层、分布层和核心层）拓扑
网络拥塞：在多数应用中，IP/以太网数据包通过TCP 协议来传输。

为保证传输可靠性和吞吐率，TCP 状态机利用窗口功能来应对动态的网络拥塞。

在拥塞期间，TCP 采用较小的窗口，从而降低吞吐率并使总体传输延迟加大。

传统的数据中心架构通常都超额配置，因此容易导致拥塞和丢包现象，从而产生较长的TCP 延迟。

Arista 的7100交换机是线速交换机（面向每个万兆以太网端口的线速性能），因此可支持非超额配置的云网络架构，提供1:1的对分带宽（如图4所示）。

构建大型的无阻塞架构(fabric)，允许TCP 能够使用大型窗口尺寸，从而提高吞吐率，降低延迟。

成百或上千个应用工作负载（不管是Web 、文件/存储、多媒体还是数据库）机器间TCP 交互都能显著受益于TCP 吞吐率和延迟的改进。

传输协议延迟：在某些低延迟环境中（如HPC ，采用Lustre 文件系统算法交易的应用），最好的解决方案是放弃TCP ，转而采用基于消息传递 (MPI)或远程直接内存存取(RDMA)的直接机器间通信。

使用Infiniband 和其他专有互连的原因就是他们具有超低延迟、高吞吐率和无损的特点。

客户渴望利用基于标准的以太网来实现此类功能和性价比优势，从而能够跨公共云或私有云经济高效地管理单一的以太网架构。

Arista 的7100系列万兆以太网交换机可提供线速和直通式低延迟性能，能够帮助建立一个统一的低延迟云网络。

Arista 的架构还支持IEEE 和IETF 关于第2/3层多路径与拥塞控制的当前及新兴的以太网标准，能够覆盖大型的无阻塞域。

大型第2层域和Arista 的低延迟线速无阻塞云网络相结合，允许用户快速迁移应用工作负载到云网络中任意地方。

低延迟应用举例：资本市场
算法交易和市场数据馈送是使用超低延迟设计的最典型应用，据说在这些环境中，“对于一家大型经纪公司，交易应用的延迟缩短1毫秒将意味着每年节省1亿美元”1。

数毫秒的延迟缩短对于经纪公司至关重要，为此他们甚至将交易系统放置在交易所内，以便能够直接获取市场数据馈送，从而消除距离造成的延迟。

当前的设计力争将交易的响应时间降至1毫秒，并计划在未来几年实现低于1毫秒的延迟设计。

出于对速度的追求，用户经常部署非主流的互连技术（比如Infiniband ），而在云架构中，这些互连的部署和管理都非常困难。

Arista 的线速以太网交换架构和Solace Systems 等生态系统合作伙伴共同推出了一个延迟为31微秒的算法交易解决方案，如图5(b)所示。

1 《Business at Light Speed 》，Richard Martin ，《信息周刊》，2007年4月
(/news/infrastructure/showArticle.jhtml?articleID=199200297)
核心路由器
无阻塞主干
分支交换机
计算节点
数据库节点
高速缓存节点
存储节点
分支交换机
分支交换机
分支交换机
图5(a): 市场数据馈送和算法交易 5(b): Arista + Solace Systems 提供超低延迟算法交易解决方案
总结
可扩展的高效云网络的兴起使万兆以太网成为首选的传输接口，用于在一个公共以太网云上同时传输数据、存储和计算信息。

许多种应用，包括资本市场的应用、高性能计算和以Web 为中心的计算等，都依赖于延迟优化型架构来实现超快速的响应。

响应时间的改进能够加速价格浮动期间算法交易的执行速度，从而确保用户的服务粘性，增强HPC 集群的可扩展性和提高交易利润。

Arista Networks 7XXX 系列交换机的设计宗旨就是应对现实世界中的云计算延迟和规模扩展问题。

Arista 和 Arista 徽标是 Arista Networks Inc 在美国和其他国家或地区的商标。

其他产品或服务名称可能是其他所有者的商标或服务标记。

市场数据供应商
买方机构
市场数据馈送
交易
星空图
(Ticker Plant)
市场数据馈送
消息传送平台
以太网交换机
交易客户端
31 usec
卖方机构
支持
support@ 408-547-5502 866-476-0000
销售
sales@ 408-547-5501 866-497-0000
总部
5470 Great America Parkway
Santa Clara, California USA95054 408-547-5500。