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118 lines
461 KiB
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<html><head><title>CDN 内容分发网络</title><meta charSet="utf-8"/><meta name="viewport" content="width=device-width, initial-scale=1.0"/><meta property="og:title" content="CDN 内容分发网络"/><meta property="og:description" content="CDN内容分发网络技术概述."/><meta property="og:image" content="https://wiki.7wate.com/static/og-image.png"/><meta property="og:width" content="1200"/><meta property="og:height" content="675"/><link rel="icon" href="../../../static/icon.png"/><meta name="description" content="CDN内容分发网络技术概述."/><meta name="generator" content="Quartz"/><link rel="preconnect" href="https://fonts.googleapis.com"/><link rel="preconnect" href="https://fonts.gstatic.com"/><script async src="https://umami.7wate.com/script.js" data-website-id="c061efdc-95dd-4d21-9d04-a1ffda0a85b9"></script><script>
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<p><img src="https://static.7wate.com/img/2023/06/27/fafe736ac748f.png" alt="内容分发网络"/></p>
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<p>内容分发网络（Content Delivery Network, CDN）是一种遍布全球的分布式服务器网络。它的主要任务是将网页和其他类型的网络内容（如图片、视频、CSS 和 JavaScript 文件）尽可能近的地方传送给用户，从而大大提高加载速度。这不仅提升了用户体验，减少了加载时间和网络延迟，也降低了源服务器的压力。</p>
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<p>比如说，<strong>CDN 的工作方式可以和京东的本地仓库次日达服务相类比</strong>。如果你在京东上购买了一台电视，京东会从离你最近的仓库发货，而不是从远离你的仓库。这样可以极大地缩短你的等待时间，从而提供更好的用户体验。</p>
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<h2 id="发展历史">发展历史<a aria-hidden="true" tabindex="-1" href="#发展历史" class="internal"> §</a></h2>
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<p>内容分发网络（CDN）的发展历程可以划分为三个主要阶段：</p>
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<ol>
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<li><strong>第一代 CDN</strong>：在这个阶段，CDN 的重点主要在于智能网络流量管理和数据中心间的联网原理，其核心任务是通过优化网络，确保数据能够快速且稳定地传输。</li>
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<li><strong>第二代 CDN</strong>：随着音频和视频流媒体服务的兴起，第二代 CDN 应运而生。这个阶段的 CDN 的工作重点转向了处理大量的音频和视频数据，确保用户能享受到流畅的媒体播放体验。</li>
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<li><strong>第三代 CDN</strong>：目前，我们正处在第三代 CDN 的发展阶段。随着移动设备的普及，用户的访问模式变得更加多元化，因此，CDN 不仅需要确保内容能快速传输，还需要应对网络环境的多样性和移动设备的特殊性。</li>
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</ol>
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<h2 id="工作原理">工作原理<a aria-hidden="true" tabindex="-1" href="#工作原理" class="internal"> §</a></h2>
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<ul>
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<li><strong>加速内容分发</strong>：CDN 将内容分发到全球的边缘服务器，当用户请求内容时，会选择离用户最近或者性能最优的服务器来处理请求，以此提高加载速度和用户体验。</li>
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<li><strong>边缘服务器的作用</strong>：边缘服务器接近用户，能够直接返回缓存的内容，避免从源服务器获取，这样能减少响应时间和网络拥塞。</li>
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<li><strong>缓存和内容复制</strong>：CDN 在边缘服务器上缓存内容，从而可以快速响应用户的请求，减少内容的加载时间和网络延迟。</li>
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<li><strong>加速和优化策略</strong>：CDN 利用一系列策略，如动态站点加速、CDN 缓存规则、HTTPS 自定义域支持、诊断日志、文件压缩和地理过滤等，来优化内容分发并提高性能。</li>
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<li><strong>处理大流量</strong>：通过分布式设计和流量调整，CDN 能够轻松处理大流量的情况，保证高性能和高可用性。</li>
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</ul>
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<h2 id="主要优势">主要优势<a aria-hidden="true" tabindex="-1" href="#主要优势" class="internal"> §</a></h2>
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<ul>
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<li><strong>提升用户体验</strong>：通过全球分布的服务器，CDN 能够减少加载时间和网络延迟，提升用户体验。</li>
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<li><strong>减轻源服务器负担</strong>：通过边缘服务器直接提供内容，CDN 能够减轻源服务器的压力，保持其性能和稳定性。</li>
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<li><strong>提供内容的地理分发</strong>：CDN 能够将内容快速地分发给全球的用户，特别适合那些拥有全球用户基础的网站或应用。</li>
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<li><strong>提高网站的可靠性和可用性</strong>：通过全球范围内的服务器分布和网络流量管理，CDN 能保证网站的高可用性。</li>
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<li><strong>增强数据安全性和防护 DDoS 攻击能力</strong>：CDN 提供了防护 DDoS 攻击的功能，并提供 SSL/TLS 加密，能够保护数据的安全性。</li>
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</ul>
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<h2 id="适用场景">适用场景<a aria-hidden="true" tabindex="-1" href="#适用场景" class="internal"> §</a></h2>
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<p><strong>阿里云 CDN 服务提供以下适用场景。</strong></p>
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<h3 id="网页站点加速">网页站点加速<a aria-hidden="true" tabindex="-1" href="#网页站点加速" class="internal"> §</a></h3>
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<p><img src="https://static.7wate.com/img/2023/06/27/2937ab538c791.png" alt="网页站点加速"/></p>
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<p>CDN 是一个全球化的服务系统，能够应对网站流量激增时的挑战。其通过全球化的服务节点和智能调度系统，让用户就近访问大量静态资源，提升网站响应速度。CDN 的费用远低于独享带宽，从而有效降低运营成本。同时，其分布式架构和高性能缓存软件保证了稳定性和效率。还具备灵活调度功能，能根据实际需求调整资源分配。</p>
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<h3 id="下载加速">下载加速<a aria-hidden="true" tabindex="-1" href="#下载加速" class="internal"> §</a></h3>
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<p><img src="https://static.7wate.com/img/2023/06/27/2937ab538c791.png" alt="下载加速"/></p>
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<p>CDN 提供了高性价比的稳定高速下载服务，支持各类大文件的下载、分发和在线点播加速。主要应用场景包括视音频点播和大文件下载。配合 OSS 接入，CDN 可以节约近 2/3 的回源带宽成本。其分布式架构和自研高性能缓存软件保证了服务的稳定性和效率。还能提供基于域名的全量实时监控和智能调度，以适应不同的服务需求。</p>
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<h3 id="视频点播">视频点播<a aria-hidden="true" tabindex="-1" href="#视频点播" class="internal"> §</a></h3>
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<p><img src="https://static.7wate.com/img/2023/06/27/e115e2978345e.png" alt="视频点播"/></p>
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<p>CDN 为用户提供一站式音视频点播解决方案，包括音视频上传、自动转码、媒体资源管理和分发加速，帮助快速搭建安全、弹性、高可定制的点播平台和应用。其特色在于提供灵活自动的媒体处理功能，用户可零开发自定义云端音视频处理流程，支持转码、截图、水印等。CDN 还提供访问控制和版权保护功能，能通过 refer 黑白名单和 URL 鉴权防止盗链。另外，其高效稳定的性能保证了播放流畅无卡顿，具有 95% 以上的命中率和毫秒级的响应时间。</p>
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<h2 id="结论">结论<a aria-hidden="true" tabindex="-1" href="#结论" class="internal"> §</a></h2>
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<p>总的来说，CDN 是实现全球快速、安全、稳定的网络内容分发的关键工具，无论对于大型互联网公司还是个体网站开发者，都是一项重要的基础设施服务。</p></article></div><div class="right sidebar"><div class="graph "><h3>Graph View</h3><div class="graph-outer"><div id="graph-container" data-cfg="{"drag":true,"zoom":true,"depth":1,"scale":1.1,"repelForce":0.5,"centerForce":0.3,"linkDistance":30,"fontSize":0.6,"opacityScale":1,"showTags":true,"removeTags":[]}"></div><svg version="1.1" id="global-graph-icon" xmlns="http://www.w3.org/2000/svg" xmlnsXlink="http://www.w3.org/1999/xlink" x="0px" y="0px" viewBox="0 0 55 55" fill="currentColor" xmlSpace="preserve"><path d="M49,0c-3.309,0-6,2.691-6,6c0,1.035,0.263,2.009,0.726,2.86l-9.829,9.829C32.542,17.634,30.846,17,29,17
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s-2-0.897-2-2s0.897-2,2-2S47,39.897,47,41z M49,10c-2.206,0-4-1.794-4-4s1.794-4,4-4s4,1.794,4,4S51.206,10,49,10z"></path></svg></div><div id="global-graph-outer"><div id="global-graph-container" data-cfg="{"drag":true,"zoom":true,"depth":-1,"scale":0.9,"repelForce":0.5,"centerForce":0.3,"linkDistance":30,"fontSize":0.6,"opacityScale":1,"showTags":true,"removeTags":[]}"></div></div></div><div class="toc desktop-only"><button type="button" id="toc" class><h3>Table of Contents</h3><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="fold"><polyline points="6 9 12 15 18 9"></polyline></svg></button><div id="toc-content"><ul class="overflow"><li class="depth-0"><a href="#引言" data-for="引言">引言</a></li><li class="depth-0"><a href="#发展历史" data-for="发展历史">发展历史</a></li><li class="depth-0"><a href="#工作原理" data-for="工作原理">工作原理</a></li><li class="depth-0"><a href="#主要优势" data-for="主要优势">主要优势</a></li><li class="depth-0"><a href="#适用场景" data-for="适用场景">适用场景</a></li><li class="depth-1"><a href="#网页站点加速" data-for="网页站点加速">网页站点加速</a></li><li class="depth-1"><a href="#下载加速" data-for="下载加速">下载加速</a></li><li class="depth-1"><a href="#视频点播" data-for="视频点播">视频点播</a></li><li class="depth-0"><a href="#结论" data-for="结论">结论</a></li></ul></div></div><div class="backlinks "><h3>Backlinks</h3><ul class="overflow"><li>No backlinks found</li></ul></div><div class="explorer mobile-only"><button type="button" id="explorer" data-behavior="collapse" data-collapsed="collapsed" data-savestate="true" data-tree="[{"path":"Journal","collapsed":true},{"path":"Journal/2024","collapsed":true},{"path":"Journal/2024/W33","collapsed":true},{"path":"Obsidian","collapsed":true},{"path":"Obsidian/Templates","collapsed":true},{"path":"Personal","collapsed":true},{"path":"Personal/Blog","collapsed":true},{"path":"Personal/Blog/2018","collapsed":true},{"path":"Personal/Blog/2020","collapsed":true},{"path":"Personal/Blog/2021","collapsed":true},{"path":"Personal/Blog/2022","collapsed":true},{"path":"Personal/Blog/2023","collapsed":true},{"path":"Personal/Blog/2024","collapsed":true},{"path":"Personal/Book","collapsed":true},{"path":"Personal/Book/个人成长","collapsed":true},{"path":"Personal/Book/医学健康","collapsed":true},{"path":"Personal/Book/历史","collapsed":true},{"path":"Personal/Book/哲学宗教","collapsed":true},{"path":"Personal/Book/心理","collapsed":true},{"path":"Personal/Book/政治军事","collapsed":true},{"path":"Personal/Book/教育学习","collapsed":true},{"path":"Personal/Book/文学","collapsed":true},{"path":"Personal/Book/生活百科","collapsed":true},{"path":"Personal/Book/社会文化","collapsed":true},{"path":"Personal/Book/科学技术","collapsed":true},{"path":"Personal/Book/经济理财","collapsed":true},{"path":"Personal/Book/艺术","collapsed":true},{"path":"Personal/Book/
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