WAAS技术白皮书

目录 1概述·······························································································································11.1产生背景······················································································································11.2 WAAS技术体系············································································································11.2.1 TCP优化············································································································11.2.2 UDP优化············································································································21.3 WAAS优化流程············································································································22WAAS技术实现···············································································································32.1 TFO技术实现···············································································································32.1.1 TFO简介············································································································32.1.2慢启动优化··········································································································32.1.3扩大接收缓冲区····································································································32.1.4拥塞控制算法优化·································································································32.1.5选择性确认··········································································································42.2 DRE技术实现···············································································································42.2.1 DRE简介············································································································42.2.2 DRE基本原理······································································································52.2.3 DRE处理流程······································································································52.3 LZ技术实现·················································································································62.3.1 LZ简介···············································································································62.3.2 LZ基本原理·········································································································62.3.3 LZ处理流程·········································································································62.4 FEC技术实现···············································································································72.4.1概念介绍·············································································································72.4.2 FEC基本原理······································································································82.4.3 FEC处理流程······································································································82.5包复制技术实现·············································································································92.5.1包复制简介··········································································································92.5.2包复制基本原理····································································································92.5.3包复制处理流程····································································································93典型组网应用·················································································································123.1 TFO+DRE优化场景·····································································································123.2 TCP/UDP单向LZ压缩·································································································13 3.3 FEC优化场景·············································································································133.4包复制优化场景···········································································································14 4参考文献·······················································································································15 1概述 1.1产生背景 随着IT基础架构的快速整合导致的数据相对集中、企业雇员全球化移动办公逐渐成为潮流，越来越多的企业应用系统交付需要通过广域网进行传输访问。广域网分支和总部数据中心之间良好的通信环境以及用户体验，不仅可以有效提升办事处的工作效率，也可以在广域网分支上为客户多元化服务提供保障。 目前，广域网承载的业务类型及业务特点如表1所示。 对于以上各类广域网业务，存在应用延时大导致用户体验差，带宽利用率不足导致部署及维护成本高，以及关键业务带宽质量无法保证的问题，因此广域网优化技术随之产生。 1.2WAAS技术体系 WAAS（Wide Area Application Services，广域网应用服务）是一种能够对广域网链路流量提供优化的技术。支持WAAS技术的设备可以通过配置优化动作，改善广域网链路高延迟、低带宽的缺点。WAAS包括TCP优化和UDP优化。 1.2.1TCP优化 TCP优化可以加速文件传输，降低网络延迟，降低丢包率，提升基于TCP的应用在广域网上的传输性能。 TCP优化支持以下几种优化技术： •TFO（Transport Flow Optimization，传输层流优化）•DRE（Data Redundancy Elimination，数据冗余消除） •LZ（Lempel-Ziv compression，LZ压缩）•包复制 1.2.2UDP优化 UDP优化可以降低丢包率，减少网络带宽的使用。UDP优化支持以下几种优化技术： •FEC（Forward Error Correction，前向冗余纠错）•LZ（Lempel-Ziv compression，LZ压缩）•包复制（仅应用层协议为RTP时支持） 1.3WAAS优化流程 如图1所示，WAAS优化涉及两个方向的流量：从LAN到WAN的流量，以及从WAN到LAN的流量。以TCP优化为例，整体优化