网络互联与实现01.ppt

* * * * Site A Site B Site C 核心层为网络提供了骨干组件或高速交换组件。在纯粹的分层设计中，核心层只完成数据交换的特殊任务。 核心层功能 核心层特点 提供高可靠性 提供冗余链路 提供故障隔离 迅速适应升级 提供较少的滞后和好的可管理性 避免由滤波器或其它处理引起的慢包操作 有有限和一致的直径 分配层 STAR-S35XX STAR-S49XX 核心层 STAR-S35XX STAR-S49XX STAR-S68XX 访问层 STAR-S19XX STAR-S21XX 选择网络产品 基于交换的层次结构示例 交换机系列 基于路由的层次结构示例 路由器系列 层次化设计的优点 可扩展性 高可用性 低时延 故障隔离 模块化 高投资回报 网络管理 实际校园网拓扑示例 SAN:存储区域网；VPN：虚拟专用网； * * 无线网络标准协议IEEE802.11a…g Emphasize: Read or state each objective so each student has a clear understanding of the chapter objectives. * Purpose: this figure states the chapter objectives. Emphasize: Read or state each objective so each student has a clear understanding of the chapter objectives. * Purpose: this figure states the chapter objectives. Emphasize: Read or state each objective so each student has a clear understanding of the chapter objectives. CSMA/CD 令牌环或FDDI * * Purpose: This page defines enterprise services. Emphasize: Enterprise services are services common to all users. Examples of enterprise services would be e-mail, Internet access, or video conferencing. Enterprise servers and services exist within a separate subnet placed close to the backbone of the network. Placing the enterprise servers close to the backbone ensures the same administrative distance from each user; however, this also means that all traffic going to an enterprise server crosses the backbone. Because enterprise services exist outside of the broadcast domain of the end user, these services are surrounding by Layer 3 functionality. The Layer 3 switch allows servers to be centralized with no performance penalty, eliminating the cost of numerous server repositories. Layer 3 devices also provide a level of security which protects the information stored on the servers. Transition: The following describes the multilayer model. * Purpose: This page defines enterprise services. Emphasize: Enterprise services are services common to all users. Examples of enterprise services would be e-mail, Internet acces