负载均衡技术白皮书

目录 1概述······························································································································31.1技术分类·····················································································································31.2技术优势·····················································································································42负载均衡技术实现············································································································52.1服务器负载均衡技术实现································································································52.1.1技术简介············································································································52.1.2工作流程············································································································62.1.3业务层级············································································································62.1.4部署模式············································································································72.1.5高可靠性············································································································92.2出方向链路负载均衡技术实现························································································152.2.1技术简介··········································································································152.2.2工作流程··········································································································162.3 DNS透明代理技术实现·································································································172.3.1技术简介··········································································································172.3.2工作流程··········································································································182.3.3设备上的业务处理流程························································································192.4入链路负载均衡技术实现······························································································212.4.1技术简介··········································································································212.4.2工作流程··········································································································212.4.3设备上的业务处理流程························································································222.5全局服务器负载均衡技术实现························································································232.5.1技术简介··········································································································232.5.2工作流程··········································································································242.5.3部署模式··········································································································263负载均衡关键技术··········································································································263.1调度算法···················································································································263.1.2基础与静态调度算法···························································································273.1.3动态与状态感知调度算法·····················································································293.1.4面向流量与带宽的调度算法··················································································303.2健康检测···················································································································303.2.1服务器健康检测·································································································30 3.2.2链路健康检测····································································································313.3负载均衡策略·············································································································333.3.1匹配规则··········································································································333.3.2负载均衡动作····································································································333.3.3会话保持··········································································································34 1概述 随着信息技术的高速发展，业务系统的访问规模和复杂度呈指数级增长。互联网应用的普及、云计算的兴起、移动终端的广泛使用，使得网络流量分布更加动态且难以预测。与此同时，用户对业务连续性、响应速度和服务质量的要求不断提升，任何服务中断或延迟都可能导致重大经济损失和品牌声誉受损。 在云化、智能化的浪潮中，网络承载的业务流量和复杂性持续攀升，如何保障服务的高可用性、低延迟和灵活扩展，已成为运营商、金融机构以及各类企业网络架构的核心诉求。 负载均衡技术提供高效便捷的流量分发服务，通过对访问流量进行分析、调度和优化，将访问流量自动分配给多个数据中心、多条链路或多台服务器，从而提高了业务处理能力，保证了业务的高可靠性。 1.1技术分类 本白皮书围绕五大核心负载均衡技术展开系统阐述，帮助读者全面理解它们的原理、优势及在运营商、金融与企业网等场景中的典型组网。 负载均衡技术可分为以下几种类型： •服务器负载均衡（SLB，Server Load Balancing）：在数据中心或企业网络中，SLB将客户端的访问请求动态分配至多台服务器进行处理，从而分担单台服务器的压力，提高整体服务的并发处理能力与可靠性。•链路负载均衡：当网络存在多条运营商链路时，此技术可动态选择合适的链路转发数据流量，从而提升链路利用率和访问质量。链路负载均衡可分为如下三种：出方向链路负载均衡：内网用户访问外部互联网存在多条链路时，可将访问流量分担到多条链路上，实现出口流量的负载均衡。DNS透明代理：当内网用户通过外部DNS服务器解析域名时，设备可对DNS请求进行透明代理。在不改变用户原有DNS配置的前提下，系统会选择最优的出口链路转发这些DNS请求，并返回经