深入淺出電腦網絡（微課視頻版）（第2版）

高軍，湖南科技大學教師，具備20年的電腦網絡課程教學經驗。在教學過程中，一直跟進電腦網絡的發展，並不斷進行教學創新。在B站發布電腦網絡微課堂系列視頻，累計播放量650萬+，深受學生喜愛。

第1章  概述································· 1 

1.1 信息時代的電腦網絡 ··················· 1 

1.1.1 電腦網絡的各類應用 ················ 1 

1.1.2 電腦網絡帶來的負面問題 ·········· 2 

1.2 因特網概述 ·································· 2 

1.2.1 網絡、因特網與因特網的區別與關系 ················ 2 

1.2.2 因特網的發展歷程 ······················ 5 

1.2.3 因特網的標準化工作和管理機構 ···· 7 

1.2.4 因特網的組成 ···························· 7 

1.3 電路交換、分組交換和報文交換 ······· 8 

1.3.1 電路交換 ·································· 8 

1.3.2 分組交換 ·································· 9 

1.3.3 報文交換 ·································12 

1.4 電腦網絡的定義和分類 ···············13 

1.4.1 電腦網絡的定義 ·····················14 

1.4.2 電腦網絡的分類 ·····················14 

1.5 電腦網絡的性能指標 ··················15 

1.5.1 速率 ···················15 

1.5.2 帶寬 ·························16 

1.5.3 吞吐量 ····································17 

1.5.4 時延 ··························17 

1.5.5 時延帶寬積 ······························20 

1.5.6 往返時間 ·································20 

1.5.7 利用率 ····································22 

1.5.8 丟包率 ····································22 

1.6 電腦網絡體系結構 ·····················23 

1.6.1 常見的三種電腦網絡體系結構 ···23 

1.6.2 電腦網絡體系結構分層的必要性 ···············27 

1.6.3 電腦網絡體系結構分層思想舉例 ················33 

1.6.4 電腦網絡體系結構中的專用術語 ·············36 

1.7 我國的電腦網絡發展情況 ············41 

1.7.1 我國的電腦網絡發展歷程 ·········41 

1.7.2 我國因特網發展情況相關資料的獲取 ····················42 

本章主要知識點和學習目標 ···················43 

本章習題·························44 

第2章  物理層 ······························48 

2.1 物理層概述 ·································48 

2.1.1 物理層要實現的功能 ··················48 

2.1.2 物理層接口特性 ························49 

2.2 物理層下麵的傳輸媒體 ··················50 

2.2.1 導向型傳輸媒體 ························50 

2.2.2 非導向型傳輸媒體 ·····················55 

2.3 傳輸方式 ····································59 

2.3.1 串行傳輸和並行傳輸 ··················59 

2.3.2 同步傳輸和異步傳輸 ··················60 

2.3.3 單向通信、雙向交替通信和雙向同時通信 ····················61 

2.4 編碼與調制 ·································62 

2.4.1 編碼與調制的基本概念 ···············62 

2.4.2 常用編碼方式 ···························63 

2.4.3 基本的帶通調制方法和混合調制方法 ························64 

2.5 通道的極限容量 ···························66 

2.5.1 奈氏準則 ·································67 

2.5.2 香農公式 ·································68 

2.6 通道復用技術 ······························69 

2.6.1 頻分復用 ·································69 

2.6.2 時分復用 ·································70 

2.6.3 波分復用 ·································70 

2.6.4 碼分復用 ·································71 

本章主要知識點和學習目標 ···················74 

關聯實驗參考指南································74 

本章習題····························74 

第3章  數據鏈路層 ·······························80 

3.1 數據鏈路層概述 ···························80 

3.1.1 數據鏈路層在網絡體系結構中所處的地位 ·················80 

3.1.2 鏈路、數據鏈路和幀 ··················81 

3.2 數據鏈路層的三個重要問題 ············82 

3.2.1 封裝成幀和透明傳輸 ··················82 

3.2.2 差錯檢測 ·································85 

3.2.3 可靠傳輸 ·································89 

3.3 點對點協議 ······························· 101 

3.3.1 PPP 協議的組成 ······················· 102 

3.3.2 PPP 協議的幀格式 ···················· 103 

3.3.3 PPP 協議的工作狀態 ················· 105 

3.4 共享式以太網 ···························· 106 

3.4.1 網絡適配器和 MAC 地址 ··········· 106 

3.4.2 CSMA/CD 協議 ······················· 111 

3.4.3 使用集線器的共享式以太網 ······· 116 

3.4.4 在物理層擴展以太網 ················ 118 

3.4.5 在數據鏈路層擴展以太網 ·········· 119 

3.5 交換式以太網 ···························· 124 

3.5.1 以太網交換機 ························· 124 

3.5.2 共享式以太網與交換式以太網的對比 ·················· 125 

3.6 以太網的 MAC 幀格式 ················· 127 

3.6.1 以太網 V2 的 MAC 幀格式 ········· 127 

3.6.2 物理層前導碼 ························· 128 

3.6.3 無效的 MAC 幀 ······················· 128 

3.7 虛擬局域網 ······························· 128 

3.7.1 虛擬局域網概述 ······················ 128 

3.7.2 虛擬局域網的實現機制 ············· 130 

3.8 以太網的發展 ···························· 135 

3.8.1 100BASE-T 以太網 ··················· 136 

3.8.2 吉比特以太網 ························· 136 

3.8.3 10 吉比特以太網 ······················ 137 

3.8.4 40 吉比特 /100 吉比特以太網 ······ 138 

3.9 802.11 無線局域網 ······················ 139 

3.9.1 802.11 無線局域網的組成 ··········· 139 

3.9.2 802.11 無線局域網的物理層 ········ 141 

3.9.3 802.11 無線局域網的數據鏈路層 ················ 142 

3.9.4 802.11 無線局域網的 MAC 幀 ····· 147 

本章主要知識點和學習目標 ················· 150 

關聯實驗參考指南······························ 150 

本章習題························ 150 

第4章  網絡層 ··························· 160 

4.1 網絡層概述 ······························· 160 

4.1.1 分組轉發和路由選擇 ················ 160 

4.1.2 網絡層向其上層提供的兩種服務 · 161 

4.2 網際協議（IP） ························· 163 

4.2.1 異構網絡互連 ························· 164 

4.2.2 IPv4 地址及其編址方法 ············· 165 

4.2.3 IPv4 地址的應用規劃 ················ 181 

4.2.4 IPv4 地址與 MAC 地址 ·············· 185 

4.2.5 地址解析協議 ························· 187 

4.2.6 IP 數據報的發送和轉發過程 ······· 192 

4.2.7 IPv4 數據報的首部格式 ············· 195 

4.3 靜態路由配置 ···························· 202 

4.3.1 直連路由和非直連路由 ············· 202 

4.3.2 默認路由和特定主機路由 ·········· 202 

4.4 因特網的路由選擇協議 ················ 204 

4.4.1 路由選擇分類 ························· 204 

4.4.2 因特網採用分層次的路由選擇協議 ··················· 204 

4.4.3 路由信息協議 ························· 205 

4.4.4 開放最短路徑優先協議 ············· 211 

4.4.5 邊界網關協議 ························· 219 

4.4.6 路由器的基本工作原理 ············· 223 

4.5 網際控制報文協議 ······················ 224 

4.5.1 ICMP 報文的種類 ···················· 224 

4.5.2 ICMP 的典型應用 ···················· 228 

4.6 虛擬專用網和網絡地址轉換 ·········· 231 

4.6.1 虛擬專用網 ···························· 231 

4.6.2 網絡地址轉換 ························· 233 

4.7 IP 多播 ·························236 

4.7.1 IP 多播技術的相關基本概念 ······· 236 

4.7.2 IP 多播地址和多播組 ················ 237 

4.7.3 在局域網上進行硬件多播 ·········· 238 

4.7.4 在因特網上進行 IP 多播需要的兩種協議 ·················· 240 

4.7.5 網際組管理協議 ······················ 241 

4.7.6 多播路由選擇協議 ··················· 246 

4.8 移動 IP 技術 ······························ 250 

4.8.1 移動性對因特網應用的影響 ······· 250 

4.8.2 移動 IP 技術的相關基本概念 ······ 251 

4.8.3 移動 IP 技術的基本工作原理 ······ 252 

4.8.4 蜂窩移動通信網中的移動性管理 ·················· 255 

4.9 下一代網際協議 IPv6 ··················· 255 

4.9.1 IPv6 引進的主要變化 ················ 256 

4.9.2 IPv6 數據報的基本首部 ············· 256 

4.9.3 IPv6 數據報的擴展首部 ············· 258 

4.9.4 IPv6 地址 ······························· 259 

4.9.5 從 IPv4 向 IPv6 過渡 ················· 262 

4.9.6 網際控制報文協議 ICMPv6 ········ 264 

4.9.7 IPv6 為中國帶來的機遇和挑戰 ···· 265 

4.10 軟件定義網絡 ··························· 265 

4.10.1 網絡層的數據層面和控制層面 ··· 265 

4.10.2 OpenFlow 協議 ······················· 267 

4.10.3 SDN 體系結構 ······················· 271 

本章主要知識點和學習目標 ················· 273 

關聯實驗參考指南······························ 274 

本章習題··················· 274 

第5章  運輸層 ······························· 288 

5.1 運輸層概述 ······························· 288 

5.1.1 進程間基於網絡的通信 ············· 288 

5.1.2 TCP/IP 體系結構運輸層中的兩個重要協議 ··················290 

5.1.3 運輸層埠號、復用與分用的概念 ··················· 291 

5.2 UDP 和 TCP 的對比 ···················· 295 

5.2.1 無連接的 UDP 和麵向連接的TCP ··················· 296 

5.2.2 UDP 和 TCP 對單播、多播和廣播的支持情況 ··········· 296 

5.2.3 UDP 和 TCP 對應用層報文的處理 ············· 297 

5.2.4 UDP 和 TCP 對數據傳輸可靠性的支持 ················ 298 

5.2.5 UDP 首部和 TCP 首部的對比 ······ 299 

5.3 傳輸控制協議 ···························· 301 

5.3.1 TCP 報文段的首部格式 ············· 301 

5.3.2 TCP 的運輸連接管理 ················ 305 

5.3.3 TCP 的流量控制 ······················ 310 

5.3.4 TCP 的擁塞控制 ······················ 314 

5.3.5 TCP 擁塞控制與網際層擁塞控制的關系 ··············· 322 

5.3.6 TCP 可靠傳輸的實現 ················ 323 

5.3.7 TCP 超時重傳時間的選擇 ·········· 328 

5.3.8 TCP 的選擇確認 ······················ 332 

5.3.9 TCP 窗口和緩存的關系 ············· 333 

本章主要知識點和學習目標 ················· 334 

關聯實驗參考指南······························ 334 

本章習題······················ 334 

第6章  應用層 ····························· 342 

6.1 應用層概述 ······························· 342 

6.2 客戶 / 服務器方式和對等方式 ········ 343 

6.2.1 客戶 / 服務器方式 ···················· 343 

6.2.2 對等方式 ······························· 344 

6.3 動態主機配置協議 ······················ 345 

6.3.1 動態主機配置協議的作用 ·········· 345 

6.3.2 動態主機配置協議的工作過程 ···· 346 

6.4 域名系統 ·································· 351 

6.4.1 域名系統的作用 ······················ 351 

6.4.2 因特網的域名結構 ··················· 352 

6.4.3 因特網上的域名服務器 ············· 354 

6.4.4 因特網的域名解析過程 ············· 354 

6.4.5 域名系統高速緩存 ··················· 356 

6.4.6 中國在 DNS 領域的進步和發展 ··· 356 

6.5 文件傳送協議 ···························· 357 

6.5.1 文件傳送協議的作用 ················ 357 

6.5.2 文件傳送協議的基本工作原理 ···· 360 

6.6 電子郵件 ·································· 361 

6.6.1 電子郵件的作用 ······················ 361 

6.6.2 電子郵件系統的組成 ················ 362 

6.6.3 簡單郵件傳送協議的基本工作過程 ····················· 363 

6.6.4 電子郵件的信息格式 ················ 364 

6.6.5 多用途因特網郵件擴展 ············· 365 

6.6.6 常用的郵件讀取協議 POP3 和IMAP4 ··············· 366 

6.6.7 基於萬維網的電子郵件 ············· 366 

6.7 萬維網 ····································· 367 

6.7.1 萬維網概述 ···························· 367 

6.7.2 統一資源定位符 ······················ 368 

6.7.3 萬維網文檔 ···························· 369 

6.7.4 超文本傳輸協議 ······················ 372 

6.7.5 使用 Cookie 在服務器上記錄信息 ············ 376 

6.7.6 萬維網緩存與代理服務器 ·········· 378 

6.7.7 中國在萬維網應用方面的發展 ···· 381 

本章主要知識點和學習目標 ················· 381 

關聯實驗參考指南······························ 382 

本章習題············ 382 

第7章  網絡安全 ··························· 388 

7.1 網絡安全概述 ···························· 388 

7.1.1 安全威脅 ······························· 388 

7.1.2 安全服務 ······························· 390 

7.2 密碼學與保密性 ························· 391 

7.2.1 密碼學相關基本概念 ················ 391 

7.2.2 對稱密鑰密碼體制 ··················· 392 

7.2.3 公鑰密碼體制 ························· 394 

7.3 報文完整性與鑒別 ····················· 395 

7.3.1 報文摘要和報文鑒別碼 ············· 395 

7.3.2 數字簽名 ······························· 399 

7.4 實體鑒別 ·································· 400 

7.5 密鑰分發 ·································· 403 

7.5.1 對稱密鑰的分發 ······················ 403 

7.5.2 公鑰的分發 ···························· 404 

7.6 訪問控制 ·································· 406 

7.6.1 訪問控制的基本概念 ················ 406 

7.6.2 訪問控制策略 ························· 407 

7.7 網絡體系結構各層採取的安全措施 ················ 408 

7.7.1 物理層安全實例：通道加密 ······· 408 

7.7.2 數據鏈路層安全實例：802.11i ···· 409 

7.7.3 網絡層安全實例：IPSec ············ 411 

7.7.4 運輸層安全實例：SSL/TLS ········ 416 

7.7.5 應用層安全實例：PGP ·············· 419 

7.8 防火牆訪問控制與入侵檢測系統 ···· 420 

7.8.1 防火牆 ·································· 421 

7.8.2 入侵檢測系統 ························· 423 

7.9 常見的網絡攻擊及其防範 ············· 424 

7.9.1 網絡掃描 ······························· 424 

7.9.2 網絡監聽 ······························· 427 

7.9.3 拒絕服務攻擊 ························· 430 

7.10 維護網絡安全從你我做起 ············ 431 

本章主要知識點和學習目標 ················· 432 

關聯實驗參考指南······························ 432 

本章習題···························· 433 

參考文獻 ···································· 437