"本书是《深入浅出计算机网络（微课视频版）》一书的升级版，本书在保留第1版结构和特点的基础上，采纳了来自一线教师和广大读者的建议和反馈，进行了全面升级，包括：增加了知识与社会和科技相结合的内容，以引导学生树立正确的价值观；每章最后新增了学习目标和丰富的习题资源，旨在帮助学生巩固知识、提高学习效率；提供实验内容的建议，以激发学生的实践能力；针对书中更新的部分，相关的微课视频也进行了同步更新。
全书共分为7章：第1章为概述，从整体上介绍计算机网络及其发展历史；第2～6章以计算机网络的五层体系结构为基础，分别介绍物理层、数据链路层、网络层、运输层和应用层的概念、工作原理、相关协议等；第7章讲述网络安全基础知识。
本书适合作为高等院校电子信息工程、通信工程、物联网工程、信息工程、电气工程及其自动化、自动化、计算机科学与技术等相关专业的教材，也可供其他专业的学生、教师和从业人员参考，还可作为考研者的复习用书。
"

第1章 概述································· 1
1.1 信息时代的计算机网络 ··················· 1
1.1.1 计算机网络的各类应用 ················ 1
1.1.2 计算机网络带来的负面问题 ·········· 2
1.2 因特网概述 ·································· 2
1.2.1 网络、互联网与因特网的区别与关系 ················ 2
1.2.2 因特网的发展历程 ······················ 5
1.2.3 因特网的标准化工作和管理机构 ···· 7
1.2.4 因特网的组成 ···························· 7
1.3 电路交换、分组交换和报文交换 ······· 8
1.3.1 电路交换 ·································· 8
1.3.2 分组交换 ·································· 9
1.3.3 报文交换 ·································12
1.4 计算机网络的定义和分类 ···············13
1.4.1 计算机网络的定义 ·····················14
1.4.2 计算机网络的分类 ·····················14
1.5 计算机网络的性能指标 ··················15
1.5.1 速率 ···················15
1.5.2 带宽 ·························16
1.5.3 吞吐量 ····································17
1.5.4 时延 ··························17
1.5.5 时延带宽积 ······························20
1.5.6 往返时间 ·································20
1.5.7 利用率 ····································22
1.5.8 丢包率 ····································22
1.6 计算机网络体系结构 ·····················23
1.6.1 常见的三种计算机网络体系结构 ···23
1.6.2 计算机网络体系结构分层的必要性 ···············27
1.6.3 计算机网络体系结构分层思想举例 ················33
1.6.4 计算机网络体系结构中的专用术语 ·············36
1.7 我国的计算机网络发展情况 ············41
1.7.1 我国的计算机网络发展历程 ·········41
1.7.2 我国互联网发展情况相关资料的获取 ····················42
本章主要知识点和学习目标 ···················43
本章习题·························44
第2章 物理层 ······························48
2.1 物理层概述 ·································48
2.1.1 物理层要实现的功能 ··················48
2.1.2 物理层接口特性 ························49
2.2 物理层下面的传输媒体 ··················50
2.2.1 导向型传输媒体 ························50
2.2.2 非导向型传输媒体 ·····················55
2.3 传输方式 ····································59
2.3.1 串行传输和并行传输 ··················59
2.3.2 同步传输和异步传输 ··················60
2.3.3 单向通信、双向交替通信和双向同时通信 ····················61
2.4 编码与调制 ·································62
2.4.1 编码与调制的基本概念 ···············62
2.4.2 常用编码方式 ···························63
2.4.3 基本的带通调制方法和混合调制方法 ························64
2.5 信道的极限容量 ···························66
2.5.1 奈氏准则 ·································67
2.5.2 香农公式 ·································68
2.6 信道复用技术 ······························69
2.6.1 频分复用 ·································69
2.6.2 时分复用 ·································70
2.6.3 波分复用 ·································70
2.6.4 码分复用 ·································71
本章主要知识点和学习目标 ···················74
关联实验参考指南································74
本章习题····························74
第3章 数据链路层 ·······························80
3.1 数据链路层概述 ···························80
3.1.1 数据链路层在网络体系结构中所处的地位 ·················80
3.1.2 链路、数据链路和帧 ··················81
3.2 数据链路层的三个重要问题 ············82
3.2.1 封装成帧和透明传输 ··················82
3.2.2 差错检测 ·································85
3.2.3 可靠传输 ·································89
3.3 点对点协议 ······························· 101
3.3.1 PPP 协议的组成 ······················· 102
3.3.2 PPP 协议的帧格式 ···················· 103
3.3.3 PPP 协议的工作状态 ················· 105
3.4 共享式以太网 ···························· 106
3.4.1 网络适配器和 MAC 地址 ··········· 106
3.4.2 CSMA/CD 协议 ······················· 111
3.4.3 使用集线器的共享式以太网 ······· 116
3.4.4 在物理层扩展以太网 ················ 118
3.4.5 在数据链路层扩展以太网 ·········· 119
3.5 交换式以太网 ···························· 124
3.5.1 以太网交换机 ························· 124
3.5.2 共享式以太网与交换式以太网的对比 ·················· 125
3.6 以太网的 MAC 帧格式 ················· 127
3.6.1 以太网 V2 的 MAC 帧格式 ········· 127
3.6.2 物理层前导码 ························· 128
3.6.3 无效的 MAC 帧 ······················· 128
3.7 虚拟局域网 ······························· 128
3.7.1 虚拟局域网概述 ······················ 128
3.7.2 虚拟局域网的实现机制 ············· 130
3.8 以太网的发展 ···························· 135
3.8.1 100BASE-T 以太网 ··················· 136
3.8.2 吉比特以太网 ························· 136
3.8.3 10 吉比特以太网 ······················ 137
3.8.4 40 吉比特 /100 吉比特以太网 ······ 138
3.9 802.11 无线局域网 ······················ 139
3.9.1 802.11 无线局域网的组成 ··········· 139
3.9.2 802.11 无线局域网的物理层 ········ 141
3.9.3 802.11 无线局域网的数据链路层 ················ 142
3.9.4 802.11 无线局域网的 MAC 帧 ····· 147
本章主要知识点和学习目标 ················· 150
关联实验参考指南······························ 150
本章习题························ 150
第4章 网络层 ··························· 160
4.1 网络层概述 ······························· 160
4.1.1 分组转发和路由选择 ················ 160
4.1.2 网络层向其上层提供的两种服务 · 161
4.2 网际协议（IP） ························· 163
4.2.1 异构网络互连 ························· 164
4.2.2 IPv4 地址及其编址方法 ············· 165
4.2.3 IPv4 地址的应用规划 ················ 181
4.2.4 IPv4 地址与 MAC 地址 ·············· 185
4.2.5 地址解析协议 ························· 187
4.2.6 IP 数据报的发送和转发过程 ······· 192
4.2.7 IPv4 数据报的首部格式 ············· 195
4.3 静态路由配置 ···························· 202
4.3.1 直连路由和非直连路由 ············· 202
4.3.2 默认路由和特定主机路由 ·········· 202
4.4 因特网的路由选择协议 ················ 204
4.4.1 路由选择分类 ························· 204
4.4.2 因特网采用分层次的路由选择协议 ··················· 204
4.4.3 路由信息协议 ························· 205
4.4.4 开放最短路径优先协议 ············· 211
4.4.5 边界网关协议 ························· 219
4.4.6 路由器的基本工作原理 ············· 223
4.5 网际控制报文协议 ······················ 224
4.5.1 ICMP 报文的种类 ···················· 224
4.5.2 ICMP 的典型应用 ···················· 228
4.6 虚拟专用网和网络地址转换 ·········· 231
4.6.1 虚拟专用网 ···························· 231
4.6.2 网络地址转换 ························· 233
4.7 IP 多播 ·························236
4.7.1 IP 多播技术的相关基本概念 ······· 236
4.7.2 IP 多播地址和多播组 ················ 237
4.7.3 在局域网上进行硬件多播 ·········· 238
4.7.4 在因特网上进行 IP 多播需要的两种协议 ·················· 240
4.7.5 网际组管理协议 ······················ 241
4.7.6 多播路由选择协议 ··················· 246
4.8 移动 IP 技术 ······························ 250
4.8.1 移动性对因特网应用的影响 ······· 250
4.8.2 移动 IP 技术的相关基本概念 ······ 251
4.8.3 移动 IP 技术的基本工作原理 ······ 252
4.8.4 蜂窝移动通信网中的移动性管理 ·················· 255
4.9 下一代网际协议 IPv6 ··················· 255
4.9.1 IPv6 引进的主要变化 ················ 256
4.9.2 IPv6 数据报的基本首部 ············· 256
4.9.3 IPv6 数据报的扩展首部 ············· 258
4.9.4 IPv6 地址 ······························· 259
4.9.5 从 IPv4 向 IPv6 过渡 ················· 262
4.9.6 网际控制报文协议 ICMPv6 ········ 264
4.9.7 IPv6 为中国带来的机遇和挑战 ···· 265
4.10 软件定义网络 ··························· 265
4.10.1 网络层的数据层面和控制层面 ··· 265
4.10.2 OpenFlow 协议 ······················· 267
4.10.3 SDN 体系结构 ······················· 271
本章主要知识点和学习目标 ················· 273
关联实验参考指南······························ 274
本章习题··················· 274
第5章 运输层 ······························· 288
5.1 运输层概述 ······························· 288
5.1.1 进程间基于网络的通信 ············· 288
5.1.2 TCP/IP 体系结构运输层中的两个重要协议 ··················290
5.1.3 运输层端口号、复用与分用的概念 ··················· 291
5.2 UDP 和 TCP 的对比 ···················· 295
5.2.1 无连接的 UDP 和面向连接的TCP ··················· 296
5.2.2 UDP 和 TCP 对单播、多播和广播的支持情况 ··········· 296
5.2.3 UDP 和 TCP 对应用层报文的处理 ············· 297
5.2.4 UDP 和 TCP 对数据传输可靠性的支持 ················ 298
5.2.5 UDP 首部和 TCP 首部的对比 ······ 299
5.3 传输控制协议 ···························· 301
5.3.1 TCP 报文段的首部格式 ············· 301
5.3.2 TCP 的运输连接管理 ················ 305
5.3.3 TCP 的流量控制 ······················ 310
5.3.4 TCP 的拥塞控制 ······················ 314
5.3.5 TCP 拥塞控制与网际层拥塞控制的关系 ··············· 322
5.3.6 TCP 可靠传输的实现 ················ 323
5.3.7 TCP 超时重传时间的选择 ·········· 328
5.3.8 TCP 的选择确认 ······················ 332
5.3.9 TCP 窗口和缓存的关系 ············· 333
本章主要知识点和学习目标 ················· 334
关联实验参考指南······························ 334
本章习题······················ 334
第6章 应用层 ····························· 342
6.1 应用层概述 ······························· 342
6.2 客户 / 服务器方式和对等方式 ········ 343
6.2.1 客户 / 服务器方式 ···················· 343
6.2.2 对等方式 ······························· 344
6.3 动态主机配置协议 ······················ 345
6.3.1 动态主机配置协议的作用 ·········· 345
6.3.2 动态主机配置协议的工作过程 ···· 346
6.4 域名系统 ·································· 351
6.4.1 域名系统的作用 ······················ 351
6.4.2 因特网的域名结构 ··················· 352
6.4.3 因特网上的域名服务器 ············· 354
6.4.4 因特网的域名解析过程 ············· 354
6.4.5 域名系统高速缓存 ··················· 356
6.4.6 中国在 DNS 领域的进步和发展 ··· 356
6.5 文件传送协议 ···························· 357
6.5.1 文件传送协议的作用 ················ 357
6.5.2 文件传送协议的基本工作原理 ···· 360
6.6 电子邮件 ·································· 361
6.6.1 电子邮件的作用 ······················ 361
6.6.2 电子邮件系统的组成 ················ 362
6.6.3 简单邮件传送协议的基本工作过程 ····················· 363
6.6.4 电子邮件的信息格式 ················ 364
6.6.5 多用途因特网邮件扩展 ············· 365
6.6.6 常用的邮件读取协议 POP3 和IMAP4 ··············· 366
6.6.7 基于万维网的电子邮件 ············· 366
6.7 万维网 ····································· 367
6.7.1 万维网概述 ···························· 367
6.7.2 统一资源定位符 ······················ 368
6.7.3 万维网文档 ···························· 369
6.7.4 超文本传输协议 ······················ 372
6.7.5 使用 Cookie 在服务器上记录信息 ············ 376
6.7.6 万维网缓存与代理服务器 ·········· 378
6.7.7 中国在万维网应用方面的发展 ···· 381
本章主要知识点和学习目标 ················· 381
关联实验参考指南······························ 382
本章习题············ 382
第7章 网络安全 ··························· 388
7.1 网络安全概述 ···························· 388
7.1.1 安全威胁 ······························· 388
7.1.2 安全服务 ······························· 390
7.2 密码学与保密性 ························· 391
7.2.1 密码学相关基本概念 ················ 391
7.2.2 对称密钥密码体制 ··················· 392
7.2.3 公钥密码体制 ························· 394
7.3 报文完整性与鉴别 ····················· 395
7.3.1 报文摘要和报文鉴别码 ············· 395
7.3.2 数字签名 ······························· 399
7.4 实体鉴别 ·································· 400
7.5 密钥分发 ·································· 403
7.5.1 对称密钥的分发 ······················ 403
7.5.2 公钥的分发 ···························· 404
7.6 访问控制 ·································· 406
7.6.1 访问控制的基本概念 ················ 406
7.6.2 访问控制策略 ························· 407
7.7 网络体系结构各层采取的安全措施 ················ 408
7.7.1 物理层安全实例：信道加密 ······· 408
7.7.2 数据链路层安全实例：802.11i ···· 409
7.7.3 网络层安全实例：IPSec ············ 411
7.7.4 运输层安全实例：SSL/TLS ········ 416
7.7.5 应用层安全实例：PGP ·············· 419
7.8 防火墙访问控制与入侵检测系统 ···· 420
7.8.1 防火墙 ·································· 421
7.8.2 入侵检测系统 ························· 423
7.9 常见的网络攻击及其防范 ············· 424
7.9.1 网络扫描 ······························· 424
7.9.2 网络监听 ······························· 427
7.9.3 拒绝服务攻击 ························· 430
7.10 维护网络安全从你我做起 ············ 431
本章主要知识点和学习目标 ················· 432
关联实验参考指南······························ 432
本章习题···························· 433
参考文献 ···································· 437