{"id":7309,"date":"2018-06-22T20:01:37","date_gmt":"2018-06-22T12:01:37","guid":{"rendered":"https:\/\/mnya.tw\/cc\/?p=7309"},"modified":"2019-06-13T11:37:53","modified_gmt":"2019-06-13T03:37:53","slug":"1149","status":"publish","type":"post","link":"https:\/\/mnya.tw\/cc\/word\/1149.html","title":{"rendered":"\u4f01\u696d\u8cc7\u6599\u901a\u8a0a(\u96fb\u8166\u7db2\u969b\u7db2\u8def) 3.4~5.4 \u91cd\u9ede\u7b46\u8a18 (\u671f\u672b\u8003\u7bc4\u570d) [\u96d9\u4eba\u7b46\u8a18]"},"content":{"rendered":"

\u4f01\u696d\u8cc7\u6599\u901a\u8a0a\u662f\u6211\u5011\u8cc7\u8a0a\u7ba1\u7406\u5b78\u7cfb\u5927\u4e00\u4e0b\u5b78\u671f\u5fc5\u4fee\u79d1\u76ee\uff0c\u4e3b\u8981\u5728\u8b1b\u96fb\u8166\u7db2\u969b\u7db2\u8def\uff0c\u671f\u4e2d\u8003\u7684\u6642\u5019\u6211\u4e5f\u6709\u767c\u4e00\u7bc7\u6587\u7ae0\u4e86\uff01\u6709\u8208\u8da3\u53ef\u4ee5\u53bb\u770b\u770b\uff0c\u671f\u672b\u8003\u5df2\u7d93\u7d50\u675f\uff0c\u60f3\u8aaa\u5df2\u7d93\u6574\u7406\u597d\u7684\u7b46\u8a18\u4e0d\u8981\u6d6a\u8cbb\uff0c\u7559\u7d66\u9700\u8981\u7684\u4eba\u4f7f\u7528\uff0c\u9019\u6b21\u671f\u672b\u8003\u7bc4\u570d\u5167\u5bb9\u6bd4\u671f\u4e2d\u8003\u591a\u975e\u5e38\u591a\uff0c\u6574\u7406\u7b46\u8a18\u7684\u6642\u9593\u5c31\u5c07\u8fd1 12 \u5c0f\u6642\uff0c\u6574\u7406\u7684\u904e\u7a0b\u9084\u662f\u53f3\u624b\u5c1a\u672a\u6062\u5fa9\u7684\u6642\u5019\uff0c\u6240\u4ee5\u904e\u7a0b\u76f8\u7576\u9700\u8981\u5c08\u6ce8\u529b\uff0c\u6700\u5f8c\u9084\u662f\u6210\u529f\u5b8c\u6210\u7b46\u8a18\u4e86\uff01\u56e0\u70ba\u8001\u5e2b\u5141\u8a31\u5e36\u96d9\u9762 A4 \u5370\u5237\u7b46\u8a18\u9032\u8003\u5834\u8003\u8a66\uff0c\u6240\u4ee5\u6211\u9084\u7279\u5225\u5c07\u81ea\u5df1\u7684\u96fb\u5b50\u7b46\u8a18\u6fc3\u7e2e\u6574\u7406\u5230\u4e00\u5f35\u96d9\u9762 A4 \u7d19\u4e0a\uff0c\u771f\u7684\u975e\u5e38\u760b\u72c2\uff0c\u5927\u7d04 4500 \u500b\u5b57\u585e\u5728\u9019\u5f35\u7d19\u4e0a\uff0c\u539f\u672c\u7684\u7b46\u8a18\u63a5\u8fd1\u4e00\u842c\u5b57\uff0c\u6211\u653e\u5728\u9019\u7684\u7b46\u8a18\u662f\u5b8c\u6574\u7248\u7684\uff0c\u63d0\u4f9b\u6587\u5b57\u6a94\u8207 PDF \u6a94\uff0c\u6211\u5011\u7684\u9032\u5ea6\u8207\u7b46\u8a18\u90fd\u662f\u53c3\u8003\u300c\u96fb\u8166\u7db2\u969b\u7db2\u8def(\u7b2c\u516d\u7248)(\u570b\u969b\u7248) [\u5168\u83ef\u5716\u66f8\u51fa\u7248]\u300d\u9019\u672c\u6559\u79d1\u66f8\u3002
\n\ud83d\udd0d \u671f\u672b\u8003\u9032\u5ea6\u70ba\uff1a3.4~5.4 (4.7\u30015.2\u30015.3 \u8df3\u904e\uff0c\u5927\u81f4\u4e0a\u70ba\u50b3\u8f38\u5c64\u3001\u7db2\u8def\u5c64\u8207\u9023\u7d50\u5c64\u7684\u4ecb\u7d39)
\n\u2b05 \u671f\u4e2d\u8003\uff1a\u4f01\u696d\u8cc7\u6599\u901a\u8a0a(\u96fb\u8166\u7db2\u969b\u7db2\u8def) 1.1~3.3 \u91cd\u9ede\u7b46\u8a18 (\u671f\u4e2d\u8003\u7bc4\u570d) [\u96d9\u4eba\u7b46\u8a18]<\/a>
\n
\n\u25b2\u300c\u96fb\u8166\u7db2\u969b\u7db2\u8def(\u7b2c\u516d\u7248)(\u570b\u969b\u7248)\u300d\u5c01\u9762\u8207\u5c01\u5e95\u6383\u63cf\u5716\u3002<\/p>\n

\u63a5\u8457\u70ba\u96fb\u5b50\u7b46\u8a18\u5206\u4eab\uff0c\u6709\u6211\u8207\u540c\u5b78\u7684\uff0c\u6211\u5011\u4e5f\u5e38\u5e38\u8a0e\u8ad6\u9019\u500b\u79d1\u76ee\u7684\u76f8\u95dc\u554f\u984c\uff0c\u5e0c\u671b\u80fd\u5e6b\u52a9\u5230\u672a\u4f86\u6709\u9700\u8981\u8b80\u9019\u500b\u9818\u57df\u7684\u4eba\uff01
\n\u203b \u82e5\u6709\u932f\u8aa4\u6b61\u8fce\u7559\u8a00\u544a\u77e5\uff0c\u672c\u6587\u7b46\u8a18\u50c5\u4f9b\u53c3\u8003\u3002<\/p>\n

\u4f01\u696d\u8cc7\u6599\u901a\u8a0a 3.4~5.4 \u91cd\u9ede\u7b46\u8a18 By \u840c\u82bd\u7ad9\u9577<\/span><\/h2>\n

\ud83d\udd36 \u7b2c\u4e09\u7ae0 (3.4\u958b\u59cb) \ud83d\udd36<\/p>\n

\ud83c\udf0f 3.4.1 \u5efa\u7acb\u53ef\u9760\u7684\u8cc7\u6599\u50b3\u8f38\u5354\u5b9a\uff1a<\/p>\n

\ud83d\udd08 \u6709\u9650\u72c0\u614b\u6a5f (finite-state Machine\uff0cFSM) \uff1a\u300a\u5206\u5b50\u300b\u9047\u5230\u4e00\u500b\u4e8b\u4ef6 \/\u300a\u5206\u6bcd\u300b\u5c55\u958b\u4ec0\u9ebc\u884c\u52d5\uff5c\u7528\u4f86\u5b9a\u7fa9\u50b3\u8f38\u7aef\u8207\u63a5\u6536\u7aef\u50b3\u8f38\u5354\u5b9a\u7684\u904b\u4f5c\u65b9\u5f0f\u3002<\/p>\n

\ud83d\udd3a rdt1.0 \u25b6 \u900f\u904e\u7d55\u5c0d\u53ef\u9760\u7684\u901a\u9053\u9032\u884c\u7684\u53ef\u9760\u8cc7\u6599\u50b3\u8f38\u3002<\/p>\n

\ud83d\udd3a rdt2.0 \u25b6 \u900f\u904e\u6703\u7522\u751f\u4f4d\u5143\u932f\u8aa4\u7684\u901a\u9053\u9032\u884c\u8cc7\u6599\u50b3\u8f38\uff0c\u9019\u985e\u5354\u5b9a\u7a31\u70ba\u505c\u6b62\u4e26\u7b49\u5f85 (stop-and-wait) \u5354\u5b9a\u3002
\n\u80af\u5b9a\u78ba\u8a8d (positive acknowledgment) (\u300cOK\u300d) \u8ddf\u5426\u5b9a\u78ba\u8a8d (negative acknowledgment) (\u300c\u8acb\u518d\u8aaa\u4e00\u6b21\u300d)\u3002
\n\ud83d\udcac \u81ea\u52d5\u91cd\u8907\u8acb\u6c42 (ARQ) \u5354\u5b9a\uff1a(1) \u932f\u8aa4\u5075\u6e2c (2) \u63a5\u6536\u7aef\u56de\u994b (3) \u91cd\u9001
\n\u26a0 ACK \u6216NAK \u640d\u6bc0\u7684\u554f\u984c\u524d\u8005\u90fd\u5c1a\u672a\u89e3\u6c7a<\/p>\n

\ud83d\udd3a rdt2.1 \u25b6 \u8cc7\u6599\u5831\u4e2d\u52a0\u5165\u4e00\u500b\u65b0\u6b04\u4f4d\uff0c\u4ee4\u50b3\u9001\u7aef\u5728\u6b64\u6b04\u4f4d\u4e2d\u653e\u5165\u5e8f\u865f(sequence number)\uff0c\u4ee5\u7de8\u865f\u5176\u8cc7\u6599\u5831\u3002<\/p>\n

\ud83d\udd3a rdt2.2 \u25b6 \u50b3\u9001\u7aef\u5982\u679c\u6536\u5230\u5169\u6b21\u91dd\u5c0d\u76f8\u540c\u5c01\u5305\u7684ACK\u8a0a\u606f [\u5373\u6536\u5230\u91cd\u8907\u7684ACK (duplicate ACK)]\uff0c\u4fbf\u6703\u77e5\u9053\u63a5\u6536\u7aef\u4e26\u672a\u6b63\u78ba\u6536\u5230\u88abACK \u78ba\u8a8d\u5169\u6b21\u7684\u5c01\u5305\u4e4b\u5f8c\u7684\u90a3\u4efd\u5c01\u5305\u3002rdt2.2 \u4e0d\u4f7f\u7528NAK\u3002
\n\u26a0 \u6bc0\u640d\u4f4d\u5143(rdt2.0\u3001rdt2.1\u3001rdt2.2)\uff5c\u907a\u5931\u5c01\u5305(rdt3.0)<\/p>\n

\ud83d\udd3a rdt3.0 \u25b6 \u900f\u904e\u6703\u767c\u751f\u4f4d\u5143\u932f\u8aa4\uff0c\u4e5f\u6703\u907a\u5931\u5c01\u5305\u7684\u901a\u9053\uff0c\u9032\u884c\u53ef\u9760\u7684\u8cc7\u6599\u50b3\u8f38\u3002(\u8b8a\u63db\u4f4d\u5143\u5354\u5b9a)
\n\u25fe\u5012\u6578\u8a08\u6642\u5668 (countdown timer) \u25b6 \u9020\u6210\u50b3\u9001\u7aef\u5230\u63a5\u6536\u7aef\u7684\u901a\u9053\u4e2d\uff0c\u6709\u53ef\u80fd\u51fa\u73fe\u91cd\u8907\u7684\u8cc7\u6599\u5c01\u5305 (duplicate data packet)\u3002<\/p>\n

\ud83c\udf0f 3.4.2 \u5efa\u7acb\u53ef\u9760\u7684\u8cc7\u6599\u50b3\u8f38\u5354\u5b9a\uff1a<\/p>\n

\ud83d\udcac rdt3.0 \u6548\u80fd\u554f\u984c\u7684\u6838\u5fc3\u5728\u65bc\u4e8b\u5be6\u4e0a\u5b83\u662f\u4e00\u7a2e\u505c\u6b62\u4e26\u7b49\u5f85\u7684\u5354\u5b9a\uff0c\u6548\u7387\u5f88\u5dee\u3002<\/p>\n

\u26a0 \u7ba1\u7dda\u5316 (pipelining) \u6703\u7522\u751f\u4e0b\u5217\u5f71\u97ff\uff1a
\n(1) \u589e\u52a0\u5e8f\u865f\u7684\u7bc4\u570d
\n(2) \u50b3\u9001\u7aef\u548c\u63a5\u6536\u7aef\u53ef\u80fd\u9700\u8981\u66ab\u5b58\u591a\u4efd\u5c01\u5305
\n(3) \u6240\u9700\u7684\u5e8f\u865f\u7bc4\u570d\u548c\u66ab\u5b58\u9700\u6c42\u53d6\u6c7a\u65bc\u8cc7\u6599\u50b3\u8f38\u5354\u5b9a\u56de\u61c9\"\u907a\u5931\u3001\u640d\u6bc0\u3001\u548c\u904e\u5ea6\u5ef6\u9072\u7684\u5c01\u5305\"\u7684\u65b9\u5f0f\u3002<\/p>\n

\ud83d\udcdd \u5169\u7a2e\u57fa\u672c\u7684\u7ba1\u7dda\u5316\u932f\u8aa4\u56de\u5fa9\u65b9\u6cd5\uff1a\u56de\u6eafN (Go-Back-N) \u8207 \u9078\u64c7\u6027\u91cd\u50b3 (selective repeat)\u3002<\/p>\n

\ud83c\udf0f 3.4.3 \u56de\u6eafN (Go-Back-N) \uff1a\u5141\u8a31\u50b3\u9001\u7aef\u53ef\u4ee5\u7121\u9700\u7b49\u5f85\u78ba\u8a8d\u4fbf\u50b3\u8f38\u591a\u4efd\u5c01\u5305\u3002[\u6ed1\u52d5\u7a97\u683c\u5354\u5b9a (sliding-window protocol)]<\/p>\n

\u25aa \u7ba1\u7dda\u4e2d\u672a\u7d93\u78ba\u8a8d\u7684\u5c01\u5305\u6700\u591a\u4e0d\u8d85\u904e\u67d0\u53ef\u5bb9\u8a31\u7684\u6700\u5927\u503cN (\u7a97\u683c\u5927\u5c0f (window size))\u3002
\n\u25ab \u5c01\u5305\u7684\u5e8f\u865f\u662f\u593e\u5e36\u5728\u5c01\u5305\u6a19\u982d\u4e2d\u67d0\u500b\u56fa\u5b9a\u9577\u5ea6\u7684\u6b04\u4f4d\u88e1\u3002\u5982\u679ck\u7b49\u65bc\u5c01\u5305\u5e8f\u865f\u6b04\u4f4d\u7684\u4f4d\u5143\u6578\uff0c\u5247\u5e8f\u865f\u7684\u7bc4\u570d\u5c31\u662f [0, 2^k \u2013 1]\u3002
\n\ud83d\udd18 TCP \u64c1\u6709 32 \u4f4d\u5143\u7684\u5e8f\u865f\u6b04\u4f4d\u3002<\/p>\n

\ud83c\udf0f 3.4.4 \u9078\u64c7\u6027\u91cd\u8907 (selective repeat, SR) \uff1a\u55ae\u4e00\u5c01\u5305\u7684\u932f\u8aa4\u53ef\u80fd\u6703\u5c0e\u81f4 GBN \u91cd\u9001\u5927\u91cf\u6c92\u6709\u5fc5\u8981\u91cd\u50b3\u5c01\u5305\uff0c\u70ba\u4e86\u907f\u514d\u524d\u8ff0\u60c5\u6cc1\uff0c\u9700\u8981\u63a5\u6536\u7aef\u500b\u5225\u5730\u78ba\u8a8d\u5df2\u6b63\u78ba\u6536\u5230\u7684\u5c01\u5305\u3002<\/p>\n

\ud83c\udf0f 3.5.1 TCP \u9023\u7dda<\/p>\n

\u2611 \u9023\u7dda\u5c0e\u5411 (connection-oriented)
\n\u2611 \u5168\u96d9\u5de5\u670d\u52d9(full-duplex service)
\n\u2611 \u9ede\u5230\u9ede (point-to-point)
\n\u2611 \u4e09\u6b21\u63e1\u624b (three-way handshake)
\n\u25aa TCP \u6703\u70ba\u6bcf\u4efd\u7528\u6236\u7aef\u8cc7\u6599\u90fd\u52a0\u4e0a TCP \u6a19\u982d\uff0c\u4ee5\u5efa\u7acb TCP \u5340\u6bb5 (TCP Segment)\u3002
\n\u25ab \u6700\u5927\u5340\u6bb5\u5927\u5c0f (Maximum Segment Size\uff0cMSS)\uff1a\u53ef\u4ee5\u5f9e\u7de9\u885d\u5340\u4e2d\u53d6\u51fa\u4e26\u653e\u5165\u5340\u6bb5\u7684\u6700\u5927\u8cc7\u6599\u91cf\u3002[\u52a0\u4e0aTCP\/IP \u6a19\u982d\u9577\u5ea6( \u5178\u578b\u503c\u70ba40\u4f4d\u5143\u7d44)]<\/p>\n

\ud83c\udf0f 3.5.2 TCP \u5340\u6bb5\u7684\u7d50\u69cb<\/p>\n

\ud83d\udd38 \u4f86\u6e90\u7aef\u8207\u76ee\u7684\u7aef\u57e0\u865f
\n\ud83d\udd38 \u6aa2\u67e5\u548c\u6b04\u4f4d
\n\ud83d\udd38 32 \u4f4d\u5143\u7684\u5e8f\u865f\u6b04\u4f4d\u548c 32 \u4f4d\u5143\u7684\u78ba\u8a8d\u7de8\u865f\u6b04\u4f4d
\n\ud83d\udd38 16 \u4f4d\u5143\u7684\u63a5\u6536\u7aef\u7a97\u683c (receive window) \u6b04\u4f4d [\u6d41\u91cf\u63a7\u5236]
\n\ud83d\udd38 4 \u4f4d\u5143\u7684\u6a19\u982d\u9577\u5ea6 (header length) \u6b04\u4f4d [\u4ee5 32 \u4f4d\u5143\u7684\u5b57\u7d44\u70ba\u55ae\u4f4d\uff0c\u4f86\u6a19\u8a18 TCP\u6a19\u982d\u9577\u5ea6]
\n\ud83d\udd38 \u65d7\u6a19\u6b04\u4f4d\u5305\u542b6\u4f4d\u5143
\n\u2560 ACK \u4f4d\u5143\uff1a\u78ba\u8a8d\u6b04\u4f4d\u4e2d\u651c\u5e36\u7684\u6578\u503c\u662f\u6709\u6548\u7684\u3002
\n\u2560 RST\u3001SYN \u8207 FIN \u4f4d\u5143\uff1a\u9023\u7dda\u7684\u5efa\u7acb\u8207\u4e2d\u65b7\u3002
\n\u2560 PSH \u4f4d\u5143\uff1a\u63a5\u6536\u7aef\u61c9\u8a72\u8981\u7acb\u523b\u5c07\u8cc7\u6599\u9001\u4ea4\u7d66\u4e0a\u5c64\u3002
\n\u255a URG \u4f4d\u5143\uff1a\u8868\u793a\u9019\u4efd\u5340\u6bb5\u5305\u542b\u88ab\u50b3\u9001\u7aef\u7684\u4e0a\u5c64\u5be6\u9ad4\u6a19\u8a18\u70ba\u300c\u7dca\u6025\u300d\u7684\u8cc7\u6599\u3002<\/p>\n

\ud83d\udd39 \u5e8f\u865f\u548c\u78ba\u8a8d\u7de8\u865f
\n\u2198 TCP \u5c07\u8cc7\u6599\u8996\u70ba\u7121\u7d50\u69cb\uff0c\u4f46\u6709\u5e8f\u7684\u4f4d\u5143\u7d44\u4e32\u6d41\u3002
\n\u2198 \u5e8f\u865f\u662f\u4ee5\u6240\u50b3\u8f38\u7684\u4f4d\u5143\u7d44\u4e32\u6d41\u4f86\u7de8\u865f\u3002
\n\u2198 \u5340\u6bb5\u7684\u5e8f\u865f\u6703\u662f\u8a72\u4efd\u5340\u6bb5\u4e2d\u7b2c\u4e00\u500b\u4f4d\u5143\u7d44\u7684\u4f4d\u5143\u7d44\u4e32\u6d41\u7de8\u865f\u3002
\n\u2198 \u4e3b\u6a5f A \u653e\u5728\u5340\u6bb5\u4e2d\u7684\u78ba\u8a8d\u7de8\u865f\uff0c\u6703\u662f\u4e3b\u6a5f A \u9810\u671f\u5f9e\u4e3b\u6a5f B \u6536\u5230\u7684\u4e0b\u4e00\u500b\u4f4d\u5143\u7d44\u7684\u5e8f\u865f\u3002
\n\u2198 TCP \u6700\u591a\u53ea\u80fd\u5920\u78ba\u8a8d\u4e32\u6d41\u4e2d\u7b2c\u4e00\u500b\u907a\u5931\u7684\u4f4d\u5143\u7d44\uff0c\u6240\u4ee5\u6211\u5011\u8aaa TCP \u63d0\u4f9b\u7684\u662f\u7d2f\u7a4d\u5f0f\u78ba\u8a8d (cumulative acknowledgement)\u3002
\n\u2198 TCP \u9023\u7dda\u7684\u5169\u7aef\u6703\u96a8\u6a5f\u9078\u64c7\u4e00\u500b\u521d\u59cb\u5e8f\u865f (\u6559\u5b78\u65b9\u4fbf\u5047\u8a2d\u70ba0)<\/p>\n

\ud83c\udf0f 3.5.3 TCP \u4f86\u56de\u6642\u9593\u7684\u7684\u8a55\u4f30\u8207\u903e\u6642 \uff1a\u5340\u6bb5\u7684RTT \u53d6\u6a23\uff0c\u6a19\u8a18\u70baSampleRTT\uff0c\u7b49\u540c\u65bc\u5f9e\u9001\u51fa\u67d0\u5340\u6bb5 ( \u610f\u5373\u4ea4\u7d66IP) \u5230\u6536\u5230\u8a72\u5340\u6bb5\u7684\u78ba\u8a8d\u8a0a\u606f\u4e4b\u9593\u6240\u7d93\u6b77\u7684\u6642\u9593\u3002 [\u7b97\u6cd5\u8acb\u53c3\u8003\u8ab2\u672c 3-50~3-52]<\/p>\n

\ud83c\udf0f 3.5.4 TCP \u53ef\u9760\u8cc7\u6599\u50b3\u8f38<\/p>\n

\ud83d\udd38 TCP \u5728 IP \u4e0d\u53ef\u9760\u7684\u76e1\u529b\u5c31\u597d\u670d\u52d9\u4e0a\uff0c\u5efa\u7acb\u4e86\u53ef\u9760\u7684\u8cc7\u6599\u50b3\u8f38\u670d\u52d9\u3002
\n\ud83d\udd38 TCP \u5efa\u8b70\u7684\u8a08\u6642\u5668\u7ba1\u7406\u7a0b\u5e8f\u53ea\u4f7f\u7528\u300c\u55ae\u4e00\u300d\u7684\u91cd\u9001\u8a08\u6642\u5668\uff0c\u5373\u4f7f\u6703\u6709\u591a\u4efd\u5df2\u50b3\u8f38\u4f46\u672a\u7d93\u78ba\u8a8d\u7684\u5340\u6bb5\u5728\u7db2\u8def\u4e2d\u3002<\/p>\n

\ud83d\udd35 \u500d\u589e\u903e\u6642\u9593\u9694<\/p>\n

\ud83d\udd38 \u6bcf\u7576 TCP \u9032\u884c\u91cd\u9001\u6642\uff0c\u5b83\u6703\u5c07\u4e0b\u6b21\u7684\u903e\u6642\u9593\u9694\u8a2d\u5b9a\u70ba\u5148\u524d\u6578\u503c\u7684\u5169\u500d\uff0c\u800c\u4e0d\u662f\u5f9e\u524d\u6b21\u7684 EstimatedRTT \u8207 DevRTT \u6240\u63a8\u5c0e\u51fa\u4f86\u3002
\n\ud83d\udd38 \u70ba\u907f\u514d\u4f86\u6e90\u7aef\u6301\u7e8c\u4e0d\u505c\u5730\u91cd\u9001\u5c01\u5305\uff0c\u9020\u6210\u64c1\u585e\u7684\u60c5\u6cc1\u8d8a\u4f86\u8d8a\u56b4\u91cd\uff0cTCP \u6703\u4f7f\u7528\u6bd4\u8f03\u6eab\u548c\u7684\u65b9\u5f0f\u4f86\u8655\u7406\uff0c\u4ee4\u50b3\u9001\u7aef\u6bcf\u6b21\u91cd\u9001\u7684\u9593\u9694\u8d8a\u4f86\u8d8a\u9577\u3002<\/p>\n

\ud83d\udd35 \u5feb\u901f\u91cd\u9001<\/p>\n

\u26a0 \u903e\u6642\u89f8\u767c\u7684\u91cd\u9001\u6a5f\u5236\uff0c\u5176\u4e2d\u4e00\u500b\u554f\u984c\u662f\u903e\u6642\u9593\u9694\u53ef\u80fd\u76f8\u7576\u9577\u3002
\n\ud83d\udd38 \u5982\u679c TCP \u50b3\u9001\u7aef\u6536\u5230\u4e09\u6b21\u540c\u4e00\u4efd\u8cc7\u6599\u7684\u91cd\u8907 ACK\uff0cTCP \u50b3\u9001\u7aef\u6703\u57f7\u884c\u5feb\u901f\u91cd\u9001 (fast retransmit)\u3002 [\u5728\u8a72\u5340\u6bb5\u7684\u8a08\u6642\u5668\u903e\u6642\u4e4b\u524d\uff0c\u4fbf\u91cd\u9001\u907a\u5931\u7684\u5340\u6bb5]<\/p>\n

\ud83d\udd35 \u56de\u6eafN \u9084\u662f \u9078\u64c7\u6027\u91cd\u8907\uff1f<\/p>\n

\ud83d\udd38 TCP \u7684\u50b3\u9001\u7aef\u53ea\u9700\u8981\u7dad\u8b77\u5df2\u9001\u51fa\u4f46\u672a\u7d93\u78ba\u8a8d\u7684\u4f4d\u5143\u7d44\u4e4b\u4e2d\u7684\u6700\u5c0f\u5e8f\u865f(SendBase)\uff0c\u4ee5\u53ca\u4e0b\u4e00\u500b\u5c07\u8981\u50b3\u9001\u7684\u4f4d\u5143\u7d44\u5e8f\u865f (NextSeqNum)\u3002\u4ee5\u6b64\u9ede\u800c\u8a00\uff0cTCP \u770b\u8d77\u4f86\u5f88\u50cf GBN \u5f0f\u7684\u5354\u5b9a\u3002
\n\ud83d\udd38 \u591a\u6578\u7684 TCP \u5be6\u4f5c\u6703\u5c07\u5df2\u7d93\u6b63\u78ba\u6536\u5230\u3001\u4f46\u812b\u5e8f\u7684\u5340\u6bb5\u5b58\u5165\"\u7de9\u885d\u5340\"\u3002<\/p>\n

\ud83c\udf0f 3.5.5 TCP\u6d41\u91cf\u63a7\u5236<\/p>\n

\ud83d\udd36 TCP \u63d0\u4f9b\u4e86\u6d41\u91cf\u63a7\u5236\u670d\u52d9 (flow-control service) \u25b6 \u6d41\u91cf\u63a7\u5236\u662f\u4e00\u7a2e\u901f\u7387\u8abf\u7bc0\u670d\u52d9\uff0c\u5b83\u6703\u5c07\u50b3\u9001\u7aef\u50b3\u9001\u8cc7\u6599\u7684\u901f\u7387\uff0c\u8abf\u6574\u81f3\u76f8\u7b26\u65bc\u63a5\u6536\u7aef\u61c9\u7528\u7a0b\u5f0f\u8b80\u53d6\u8cc7\u6599\u7684\u901f\u7387\u3002
\n\ud83d\udd38 TCP\u6703\u85c9\u7531\u8b93\u50b3\u9001\u7aef\u7dad\u8b77\u4e00\u500b\u7a31\u70ba\u63a5\u6536\u7a97\u683c (receive window) \u7684\u8b8a\u6578\uff0c\u4f86\u63d0\u4f9b\u6d41\u91cf\u63a7\u5236\u3002\u975e\u6b63\u5f0f\u5730\u8aaa\uff0c\u63a5\u6536\u7a97\u683c\u662f\u7528\u4f86\u8b93\u50b3\u9001\u7aef\u5c0d\u65bc\u63a5\u6536\u7aef\u6709\u591a\u5c11\u53ef\u7528\u7684\u7de9\u885d\u5340\u7a7a\u9593\u5f97\u5230\u4e00\u4e9b\u6982\u5ff5\u3002<\/p>\n

\ud83c\udf0f 3.5.6 TCP \u9023\u7dda\u7ba1\u7406<\/p>\n

\ud83d\udd35 \u9023\u7dda\u5efa\u7acb \u25b6 \u4e09\u6b21\u63e1\u624b (three-way handshake)<\/p>\n

\ud83d\udd18 \u6b65\u9a5f\u4e00\uff1a\u7528\u6236\u7aef TCP \u6703\u5148\u50b3\u9001\u4e00\u7b46\u7279\u6b8a\u7684 TCP SYN \u5340\u6bb5\u7d66\u4f3a\u670d\u7aefTCP\u3002SYN\u4f4d\u5143\u6703\u88ab\u8a2d\u5b9a\u70ba 1\u3002\u7528\u6236\u7aef\u6703\u96a8\u6a5f\u9078\u64c7\u4e00\u500b\u521d\u59cb\u5e8f\u865f (client_isn) \u3002
\n\ud83d\udd18 \u6b65\u9a5f\u4e8c\uff1a\u4f3a\u670d\u7aef\u4fbf\u6703\u5f9e\u8cc7\u6599\u5831\u4e2d\u53d6\u51fa TCP SYN \u5340\u6bb5\uff0c\u914d\u7f6e TCP \u7de9\u885d\u5340\u8207\u8b8a\u6578\u7d66\u8a72\u7b46\u9023\u7dda\uff0c\u7136\u5f8c\u9001\u51fa\u4e00\u7b46\u9023\u7dda\u8a31\u53ef SYNACK \u5340\u6bb5\u7d66\u7528\u6236\u7aef TCP\u3002SYN\u4f4d\u5143\u6703\u88ab\u8a2d\u5b9a\u70ba1\u3002TCP \u5340\u6bb5\u6a19\u982d\u7684\u78ba\u8a8d\u6b04\u4f4d\u6703\u88ab\u8a2d\u5b9a\u70ba client_isn+1\u3002
\n\ud83d\udd18 \u6b65\u9a5f\u4e09\uff1a\u4e00\u65e6\u6536\u5230 SYNACK \u5340\u6bb5\uff0c\u7528\u6236\u7aef\u4e5f\u6703\u914d\u7f6e\u7de9\u885d\u5340\u8207\u8b8a\u6578\u7d66\u8a72\u7b46\u9023\u7dda\u3002\u9019\u4e09\u6b21\u63e1\u624b\u7684\u7b2c\u4e09\u968e\u6bb5\uff0c\u6709\u53ef\u80fd\u6703\u5728\u5340\u6bb5\u5167\u5bb9\u4e2d\u651c\u5e36\u7528\u6236\u7aef\u7d66\u4f3a\u670d\u7aef\u7684\u8cc7\u6599\u3002<\/p>\n

\ud83d\udd35 \u95dc\u9589\u9023\u7dda\uff1a\u53c3\u8207TCP\u9023\u7dda\u7684\u5169\u7b46\u884c\u7a0b\uff0c\u4efb\u4e00\u65b9\u90fd\u53ef\u4ee5\u7d50\u675f\u8a72\u7b46\u9023\u7dda\u3002<\/p>\n

\ud83c\udf0f 3.6.2 \u58c5\u585e\u63a7\u5236\u7684\u65b9\u6cd5<\/p>\n

\ud83d\udd38 \u7aef\u9ede\u5230\u7aef\u9ede\u7684\u58c5\u585e\u63a7\u5236\uff1a\u7db2\u8def\u5c64\u4e26\u4e0d\u6703\u70ba\u4e86\u58c5\u585e\u63a7\u5236\uff0c\u63d0\u4f9b\u50b3\u8f38\u5c64\u4efb\u4f55\u660e\u78ba\u7684\u5354\u52a9\u3002\u751a\u81f3\u7d42\u7aef\u7cfb\u7d71\u53ea\u80fd\u6839\u64da\u6240\u89c0\u5bdf\u5230\u7684\u7db2\u8def\u884c\u70ba\u4f86\u63a8\u6e2c\u7db2\u8def\u4e2d\u662f\u5426\u767c\u751f\u58c5\u585e\u3002
\n\ud83d\udd38 \u7db2\u8def\u5354\u52a9\u7684\u58c5\u585e\u63a7\u5236\uff1a\u7db2\u8def\u5c64\u5143\u4ef6(\u5373\u8def\u7531\u5668)\u6703\u63d0\u4f9b\u660e\u78ba\u7684\u56de\u994b\u8cc7\u8a0a\u7d66\u50b3\u9001\u7aef\uff0c\u544a\u77e5\u5176\u7db2\u8def\u58c5\u585e\u7684\u72c0\u6cc1\u3002
\n\u2198 \u8def\u7531\u5668\u50b3\u9001\u76f4\u63a5\u7684\u56de\u994b\u7d66\u50b3\u9001\u7aef\u3002\u9019\u662f\u63a1\u7528\u627c\u5236\u5c01\u5305 (choke packet)\u300c\u6211\u5df2\u7d93\u58c5\u585e\u4e86\uff01\u300d\u7684\u5f62\u5f0f\u4f86\u9032\u884c\u3002
\n\u2198 \u8def\u7531\u5668\u6703\u6a19\u8a18\u6216\u66f4\u65b0\u5f9e\u50b3\u9001\u7aef\u6d41\u5f80\u63a5\u6536\u7aef\u7684\u67d0\u500b\u5c01\u5305\u6b04\u4f4d\uff0c\u4ee5\u6307\u793a\u58c5\u585e\u72c0\u6cc1\u3002<\/p>\n

\ud83c\udf0f 3.7 TCP \u58c5\u585e\u63a7\u5236<\/p>\n

\ud83d\udd18 \u58c5\u585e\u7a97\u683c (congestion window)\uff0c\u4ee5 cwnd \u8868\u793a\uff0c\u6703\u9650\u5236 TCP \u50b3\u9001\u7aef\u80fd\u5920\u5c07\u8cc7\u6599\u6d41\u9001\u5165\u7db2\u8def\u7684\u901f\u7387\u3002
\n\ud83d\udd18 ssthresh (\u4ee3\u8868\u300c\u7de9\u555f\u52d5\u9580\u6abb (slow start threshold)\u300d\u7684\u7e2e\u5beb)<\/p>\n

\ud83d\udd38 \u7de9\u555f\u52d5\uff1a\u958b\u59cb TCP \u9023\u7dda\u6642\uff0ccwnd \u503c\u901a\u5e38\u6703\u88ab\u521d\u59cb\u5316\u70ba\u67d0\u500b\u5c0f\u6578\u503c 1 MSS\uff0c\u50b3\u9001\u901f\u7387\u6703\u4ee5\u4f4e\u901f\u958b\u59cb\uff0c\u4f46\u662f\u5728\u7de9\u555f\u52d5\u968e\u6bb5\u4e2d\u6703\u6307\u6578\u6027\u5730\u6210\u9577\u3002
\n\u2198 \u7576 cwnd \u503c\u7b49\u65bc ssthresh \u6642\uff0c\u4e5f\u5c31\u662f\u4e0a\u6b21\u767c\u751f\u58c5\u585e\u7684\u7a97\u683c\u7684\u4e00\u534a\u6642\uff0c\u7de9\u555f\u52d5\u6703\u7d42\u6b62\uff0cTCP \u6703\u8f49\u63db\u9032\u5165\u58c5\u585e\u8ff4\u907f\u6a21\u5f0f\u3002
\n\u2198 \u7576\u767c\u751f\u903e\u6642\u4e8b\u4ef6\uff0c\u6703\u5c07\u7684\u6578\u503c\u8a2d\u5b9a\u70ba\u58c5\u585e\u60c5\u6cc1\u6642\u7a97\u683c\u7684\u4e00\u534a cwnd\/2\uff1b\u800c cwnd = 1 MSS\u3002
\n\u2198 \u7576\u5075\u6e2c\u5230\u4e09\u6b21\u91cd\u8907 ACK \u6642\uff0cTCP \u6703\u57f7\u884c\u5feb\u901f\u91cd\u9001\uff0c\u4e26\u4e14\u9032\u5165\u5feb\u901f\u5fa9\u539f\u72c0\u614b\uff0c\u4e14\u8a2d\u5b9a\u53c3\u6578\uff1assthresh = cwnd \/ 2; cwnd = ssthresh + 3 MSS\u3002
\n\ud83d\udd36 \u58c5\u585e\u8ff4\u907f\uff1a\u5728\u6bcf\u56de RTT \u4e2d\u53ea\u6703\u5c07 cwnd \u503c\u589e\u52a0\u4e00\u500b MSS\u3002
\n\ud83d\udd36 \u5feb\u901f\u5fa9\u539f \uff1a\u6bcf\u6536\u5230\u4e00\u6b21\u9020\u6210 TCP \u9032\u5165\u5feb\u901f\u5fa9\u539f\u72c0\u614b\u7684\u907a\u5931\u5340\u6bb5\u91cd\u8907ACK\uff0ccwnd \u503c\u4fbf\u6703\u88ab\u589e\u52a0 1 MSS\u3002
\n\u2198 \u7576\u907a\u5931\u7684\u5340\u6bb5\u5230\u9054\u6642\uff0c\u6b63\u78ba\u7684ACK\u4e8b\u4ef6\uff0c\u5728 TCP Reno \u4e2d\uff0c\u58c5\u585e\u7a97\u683c\u6703\u88ab\u8a2d\u5b9a\u70ba cwnd = ssthresh\uff0c\u7136\u5f8c\u958b\u59cb\u4ee5\u7dda\u6027\u65b9\u5f0f\u589e\u9577\u3002
\n\u2198 \u5728 TCP Tahoe \u4e2d\uff0c\u58c5\u585e\u7a97\u683c\u5247\u6703\u88ab\u8a2d\u5b9a\u70ba1 MSS\uff0c\u7136\u5f8c\u6307\u6578\u5f0f\u5730\u589e\u9577\u76f4\u5230\u9054\u5230 ssthresh \u503c\u70ba\u6b62\uff0c\u6b64\u6642\u58c5\u585e\u7a97\u683c\u6703\u958b\u59cb\u7dda\u6027\u5730\u589e\u9577\u3002<\/p>\n

\ud83d\udd35 TCP \u7684\u58c5\u585e\u63a7\u5236\u7a31\u4f5c\u7d2f\u9032\u905e\u589e\uff0c\u500d\u6578\u524a\u6e1b(AIMD)\u7684\u58c5\u585e\u63a7\u5236\u5f62\u5f0f\u3002
\n\ud83d\udd35 \u76ee\u524d\u5927\u591a\u6578\u7684 TCP \u5be6\u4f5c\u6240\u4f7f\u7528\u7684\u90fd\u662f Reno \u6f14\u7b97\u6cd5\u3002
\n\u2796\u2796\u2796\u2796\u2796\u2796\u2796\u2796\u2796\u2796\u2796
\n\u26a0 3.6.1 \u8df3\u904e\uff0c\u8acb\u76f4\u63a5\u53c3\u8003\u8ab2\u672c\u5167\u5bb9\u3002
\n\u2796\u2796\u2796\u2796\u2796\u2796\u2796\u2796\u2796\u2796\u2796
\n\ud83d\udd36 \u7b2c\u56db\u7ae0 \ud83d\udd36<\/p>\n

\ud83c\udf0f 4.1.1 \u8f49\u9001\u8207\u7e5e\u9001<\/p>\n

\ud83d\udd3a \u8f49\u9001 (Forwarding)\uff1a\u7576\u5c01\u5305\u62b5\u9054\u8def\u7531\u5668\u7684\u8f38\u5165\u9023\u7d50\u6642\uff0c\u8def\u7531\u5668\u5fc5\u9808\u5c07\u9019\u4efd\u5c01\u5305\u79fb\u52d5\u5230\u9069\u7576\u7684\u8f38\u51fa\u9023\u7d50\u3002 [\u8def\u7531\u5668\u5167\uff0c\u8f38\u5165\u9023\u7d50 \u27a1 \u8f38\u51fa\u9023\u7d50]
\n\ud83d\udd3a \u7e5e\u9001 (Routing)\uff1a\u7db2\u8def\u5c64\u5fc5\u9808\u5224\u65b7\u5c01\u5305\u5f9e\u50b3\u9001\u7aef\u6d41\u5411\u63a5\u6536\u7aef\u6642\u6240\u63a1\u53d6\u7684\u8def\u7531\u6216\u8def\u5f91\u3002\u8a08\u7b97\u9019\u4e9b\u8def\u5f91\u7684\u6f14\u7b97\u6cd5\u7a31\u70ba\u7e5e\u9001\u6f14\u7b97\u6cd5 (routing algorithm)\u3002 [\u6240\u6709\u7684\u8def\u7531\u5668\u90fd\u6709\u95dc\uff0c\u6574\u9ad4\u6027]<\/p>\n

\ud83d\udd18 \u6bcf\u500b\u8def\u7531\u5668\u90fd\u64c1\u6709\u4e00\u4efd\u8f49\u9001\u8868 (forwarding table)\u3002
\n\ud83d\udd18 \u8def\u7531\u5668\u6703\u63a5\u6536\u7e5e\u9001\u5354\u5b9a\u8a0a\u606f\uff0c\u4ee5\u7528\u4f86\u8a2d\u5b9a\u5176\u8f49\u9001\u8868\u3002<\/p>\n

\ud83c\udf0f 4.1.2 \u7db2\u8def\u670d\u52d9\u6a21\u578b<\/p>\n

\ud83d\udd18 \u7db2\u8def\u5c64\u53ef\u80fd\u63d0\u4f9b\u7684\u4e00\u4e9b\u670d\u52d9\u5305\u62ec\uff1a
\n\u2611 \u6295\u905e\u4fdd\u969c (guaranteed delivery)
\n\u2611 \u6709\u9650\u5ef6\u9072\u7684\u6295\u905e\u4fdd\u969c (guaranteed delivery with bounded delay)
\n\u2611 \u4f9d\u5e8f\u7684\u5c01\u5305\u6295\u905e (in-order packet delivery)
\n\u2611 \u6700\u4f4e\u983b\u5bec\u4fdd\u969c(guaranteed minimal bandwidth)
\n\u2611 \u6700\u5927\u6642\u57fa\u8aa4\u5dee\u4fdd\u969c (guaranteed maximum jitter)
\n\u2611 \u5b89\u5168\u6027\u670d\u52d9 (Security service)
\n\u27a1 \u7db2\u969b\u7db2\u8def\u7684\u7db2\u8def\u5c64\u53ea\u63d0\u4f9b\u4e00\u7a2e\u670d\u52d9\uff0c\u7a31\u70ba\u76e1\u529b\u800c\u70ba\u7684\u670d\u52d9 (best-effort service) [\u5373\u4e0d\u63d0\u4f9b\u4efb\u4f55\u670d\u52d9]\u3002<\/p>\n

\ud83d\udd38 \u5176\u4ed6\u9078\u64c7\uff1a
\n\u2198 \u56fa\u5b9a\u4f4d\u5143\u50b3\u8f38\u901f\u7387ATM\u7db2\u8def\u670d\u52d9
\n\u2198 \u53ef\u7528\u4f4d\u5143\u50b3\u8f38\u901f\u7387ATM\u7db2\u8def\u670d\u52d9<\/p>\n

\ud83c\udf0f 4.2.1 \u865b\u64ec\u8ff4\u8def\u7db2\u8def<\/p>\n

\ud83d\udd18 \u865b\u64ec\u8ff4\u8def (virtual circuit\uff0cVC) \u2194 \u7db2\u8def\u5c64 \u9023\u7dda\u670d\u52d9<\/p>\n

\ud83d\udd38 \u4e00\u689d VC \u5305\u542b\uff1a
\n(1) \u4e00\u689d\u5f9e\u4f86\u6e90\u7aef\u4e3b\u6a5f\u5230\u76ee\u7684\u7aef\u4e3b\u6a5f\u4e4b\u9593\u7684\u8def\u5f91 ( \u5373\u4e00\u9023\u4e32\u7684\u9023\u7d50\u53ca\u8def\u7531\u5668) \u3002
\n(2) VC \u7de8\u865f\uff0c\u8def\u5f91\u4e0a\u7684\u6bcf\u9053\u9023\u7d50\u90fd\u6703\u6709\u4e00\u500b\u7de8\u865f\u3002
\n(3) \u8def\u5f91\u4e0a\u6240\u6709\u8def\u7531\u5668\u7684\u8f49\u9001\u8868\u9805\u76ee\u3002\u5c6c\u65bc\u67d0\u689d\u865b\u64ec\u8ff4\u8def\u7684\u5c01\u5305\uff0c\u6703\u5728\u5176\u6a19\u982d\u4e2d\u593e\u5e36\u4e00\u5247 VC \u7de8\u865f\u3002\u56e0\u70ba\u865b\u64ec\u8ff4\u8def\u5728\u6bcf\u9053\u9023\u7d50\u4e0a\u7684 VC \u7de8\u865f\u53ef\u80fd\u90fd\u6709\u6240\u4e0d\u540c\uff0c\u6240\u4ee5\u6bcf\u53f0\u4e2d\u4ecb\u7684\u8def\u7531\u5668\u90fd\u5fc5\u9808\u5c07\u6bcf\u500b\u901a\u904e\u7684\u5c01\u5305 VC \u7de8\u865f\u63db\u6210\u65b0\u7684 VC \u7de8\u865f\u3002\u9019\u500b\u65b0\u7684 VC \u7de8\u865f\u662f\u5f9e\u8f49\u9001\u8868\u53d6\u5f97\u3002<\/p>\n

\ud83d\udcac \u6bcf\u7576\u6709\u4e00\u689d\u65b0\u7684\uff0c\u8de8\u67d0\u53f0\u8def\u7531\u5668\u7684 VC \u88ab\u5efa\u7acb\u8d77\u4f86\u6642\uff0c\u4fbf\u6709\u4e00\u7b46\u65b0\u9805\u76ee\u88ab\u52a0\u5165\u5230\u8f49\u9001\u8868\u4e2d\u3002\u7576 VC \u7d42\u7d50\u6642\uff0c\u5176\u8def\u5f91\u4e0a\u6bcf\u4efd\u8f49\u9001\u8868\u4e2d\u7684\u5c0d\u61c9\u9805\u76ee\u4e5f\u90fd\u6703\u88ab\u79fb\u9664\u3002
\n\ud83d\udcac \u8def\u7531\u5668\u5fc5\u9808\u7dad\u8b77\u904b\u4f5c\u4e2d\u4e4b\u9023\u7dda\u7684\u9023\u7dda\u72c0\u614b\u8cc7\u8a0a(connection state information)\u3002<\/p>\n

\ud83d\udd18 VC \u4e09\u500b\u968e\u6bb5\uff1a(1) \u5efa\u7acb VC (2) \u8cc7\u6599\u50b3\u8f38 (3) VC\u65b7\u7dda<\/p>\n

\u25aa \u4fe1\u865f\u8a0a\u606f (signaling message)\uff1a\u4fee\u6539\u8def\u7531\u5668\u8f49\u9001\u8868\u4e2d\u7684\u9023\u7dda\u72c0\u614b\u3002
\n\u25ab \u4fe1\u865f\u767c\u9001\u5354\u5b9a (signaling protocol)\uff1a\u4fe1\u865f\u8a0a\u606f\u7684\u5354\u5b9a\u3002<\/p>\n

\ud83c\udf0f 4.2.2 \u8cc7\u6599\u5831\u7db2\u8def<\/p>\n

\ud83d\udd38 \u8cc7\u6599\u5831\u7db2\u8def (datagram network) \u4e0d\u9700\u8981\u5efa\u7acb\u4efb\u4f55 VC\u3002
\n\ud83d\udd18 \u6bcf\u53f0\u8def\u7531\u5668\u90fd\u6703\u5229\u7528\u5c01\u5305\u7684\u76ee\u7684\u7aef\u4f4d\u5740\u4f86\u8f49\u9001\u5c01\u5305\u3002
\n\ud83d\udd18 \u5c01\u5305\u62b5\u9054\u8def\u7531\u5668\u6642\uff0c\u8def\u7531\u5668\u4fbf\u6703\u4f7f\u7528\u5c01\u5305\u7684\u76ee\u7684\u7aef\u4f4d\u5740\u4f86\u67e5\u8a62\u8f49\u9001\u8868\uff0c\u4ee5\u627e\u51fa\u9069\u7576\u7684\u8f38\u51fa\u9023\u7d50\u4ecb\u9762\u3002
\n\ud83d\udd39 \u5740\u9996 (prefix) \u8207\u8868\u683c\u4e2d\u7684\u9805\u76ee\u9032\u884c\u6bd4\u5c0d\uff0c\u4ee5\u5c07\u5c01\u5305\u6b63\u78ba\u8f49\u9001\uff0c\u591a\u7b46\u76f8\u7b26\u7684\u9805\u76ee\u6642\uff0c\u8def\u7531\u5668\u6703\u63a1\u7528\u6700\u9577\u5740\u9996\u76f8\u7b26\u539f\u5247 (longest prefix matching rule)\u3002
\n\ud83d\udd39 \u8f49\u9001\u8868\u662f\u7531\u7e5e\u9001\u6f14\u7b97\u6cd5\u6240\u4fee\u8a02\uff0c\u901a\u5e38\u6bcf\u9694\u4e00\u5230\u4e94\u5206\u9418\u5de6\u53f3\u66f4\u65b0\u4e00\u6b21\u3002
\n\ud83d\udd3a \u4e00\u9023\u4e32\u5c01\u5305\uff0c\u53ef\u80fd\u6703\u4e0d\u4f9d\u539f\u672c\u7684\u9806\u5e8f\u62b5\u9054\u76ee\u7684\u7aef\u3002<\/p>\n

\ud83c\udf0f 4.2.3 VC \u8207\u8cc7\u6599\u5831\u7db2\u8def\u7684\u8d77\u6e90<\/p>\n

\u865b\u64ec\u8ff4\u8def \u2194\ufe0f \u96fb\u8a71\u7cfb\u7d71
\n\u8cc7\u6599\u5831\u7db2\u8def \u2194\ufe0f \u76e1\u53ef\u80fd\u5730\u7c21\u55ae<\/p>\n

\ud83c\udf0f 4.3 \u8def\u7531\u5668\u7684\u5167\u90e8\u6709\u4ec0\u9ebc\uff1f<\/p>\n

\ud83d\udd38 \u8f38\u5165\u57e0 (input port)\uff1a\u6703\u57f7\u884c\u5be6\u9ad4\u5c64\u8207\u9023\u7d50\u5c64\u529f\u80fd\u3002
\n\ud83d\udd38 \u4ea4\u63db\u7d50\u69cb (switching fabric)
\n\u2198 \u7d93\u7531\u8a18\u61b6\u9ad4\u9032\u884c\u4ea4\u63db\uff1a\u540c\u4e00\u500b\u6642\u9593\u53ea\u6709\u4e00\u7b46\u7684\u8a18\u61b6\u9ad4\u8b80\u51fa\uff0f\u5beb\u5165\u53ef\u88ab\u5b8c\u6210\u3002
\n\u2198 \u900f\u904e\u532f\u6d41\u6392 (bus) \u9032\u884c\u4ea4\u63db\uff1a\u6bcf\u4e00\u500b\u5c01\u5305\u90fd\u5fc5\u9808\u6a6b\u8d8a\u55ae\u4e00\u4e00\u500b\u532f\u6d41\u6392\uff0c\u6240\u4ee5\u8def\u7531\u5668\u7684\u4ea4\u63db\u901f\u5ea6\u53d7\u9650\u65bc\u532f\u6d41\u6392\u7684\u901f\u5ea6\u3002
\n\u2198 \u900f\u904e\u4e92\u9023\u7db2\u8def\u9032\u884c\u4ea4\u63db\uff1a\u68cb\u76e4\u5f0f\u4ea4\u63db\u7d50\u69cb (crossbar switch) \u5c07 N\u500b\u8f38\u5165\u57e0\u9023\u63a5\u5230 N \u500b\u8f38\u51fa\u57e0\u7684\u4e92\u9023\u7db2\u8def\u3002\u53ef\u4ee5\u5728\u540c\u4e00\u6642\u9593\u8f49\u9001\u591a\u500b\u5c01\u5305\u3002\u7136\u800c\uff0c\u5047\u5982\u5169\u500b\u4f86\u81ea\u4e0d\u540c\u8f38\u5165\u57e0\u7684\u5c01\u5305\u662f\u8981\u524d\u5f80\u76f8\u540c\u7684\u8f38\u51fa\u57e0\uff0c\u90a3\u9ebc\u5176\u4e2d\u4e00\u500b\u5fc5\u9808\u8981\u5728\u8f38\u5165\u8655\u7b49\u5f85\uff0c\u56e0\u70ba\u5728\u540c\u4e00\u6642\u9593\u53ea\u6709\u4e00\u500b\u5c01\u5305\u53ef\u4ee5\u5728\u4efb\u610f\u7d66\u5b9a\u7684\u532f\u6d41\u6392\u4e0a\u50b3\u9001\u3002
\n\ud83d\udd38 \u8f38\u51fa\u57e0 (output port)\uff1a\u8f38\u51fa\u57e0\u6703\u5c07\u7d93\u7531\u4ea4\u63db\u7d50\u69cb\u8f49\u9001\u4f86\u7684\u5c01\u5305\u5132\u5b58\u8d77\u4f86\uff0c\u63a5\u8457\u85c9\u7531\u57f7\u884c\u5fc5\u9808\u7684\u9023\u7d50\u5c64\u8207\u5be6\u9ad4\u5c64\u529f\u80fd\u5c07\u9019\u4e9b\u5c01\u5305\u8f38\u9001\u5230\u8f38\u51fa\u9023\u7d50\u3002
\n\ud83d\udd38 \u7e5e\u9001\u8655\u7406\u5668 (Routing processor)\uff1a\u57f7\u884c\u7e5e\u9001\u5354\u5b9a \uff0c\u7dad\u8b77\u7e5e\u9001\u8868\u548c\u9023\u7d50\u72c0\u614b\u8cc7\u8a0a\uff0c\u4e26\u70ba\u8def\u7531\u5668\u8a08\u7b97\u8f49\u9001\u8868\u3002<\/p>\n

\ud83d\udcac \u4f47\u5217\u53ef\u80fd\u767c\u751f\u5728\u8f38\u5165\u57e0&\u8f38\u51fa\u57e0\uff0c\u8def\u7531\u5668\u7684\u8a18\u61b6\u9ad4\u8017\u76e1\u6703\u5c0e\u81f4\u5c01\u5305\u907a\u5931\u3002
\n\ud83d\udcac \u5c01\u5305\u6392\u7a0b\u5668 (packet scheduler) \u27a1 \u63d0\u4f9b\u670d\u52d9\u54c1\u8cea (quality-of-service, QoS) \u4fdd\u969c\u3002<\/p>\n

\ud83d\udd39 \u4e3b\u52d5\u5f0f\u4f47\u5217\u7ba1\u7406 (active queue management, AQM) \u27a1 \u53bb\u5c3e (drop-tail)
\n\ud83d\udd39 \u96a8\u6a5f\u5f0f\u65e9\u671f\u5075\u6e2c (Random Early Detection\uff0cRED)
\n\ud83d\udd39 \u4f47\u5217\u524d\u7aef\u6514\u963b (head-of-the-line blocking\uff0cHOL blocking)\uff1a\u5982\u679c\u4ea4\u63db\u7d50\u69cb\u7684\u901f\u5ea6\u4e0d\u5920\u5feb\uff0c\u5c01\u5305\u4f47\u5217\u4e5f\u6703\u767c\u751f\u5728\u8f38\u5165\u57e0\u4e2d\u3002<\/p>\n

\ud83c\udf0f 4.4 IP\u7db2\u969b\u7db2\u8def\u7684\u8f49\u9001\u8207\u5b9a\u5740<\/p>\n

\ud83d\udd38 \u4e09\u5143\u4ef6\uff1aIP \u5354\u5b9a\u3001\u7e5e\u9001\u5143\u4ef6\u3001\u56de\u5831\u932f\u8aa4<\/p>\n

\ud83c\udf0f 4.4.1 \u8cc7\u6599\u5831\u683c\u5f0f<\/p>\n

\ud83d\udd18 \u7248\u672c\u7de8\u865f (version number)
\n\ud83d\udd18 \u6a19\u982d\u9577\u5ea6 (header length)\uff1aIPv4 \u8cc7\u6599\u5831\u6709\u53ef\u80fd\u5305\u542b\u4e0d\u540c\u6578\u91cf\u7684\u9078\u7528\u6b04\u4f4d\uff0c\u6240\u4ee5\u9700\u8981\u9019 4 \u500b\u4f4d\u5143\u4f86\u5224\u65b7 IP \u8cc7\u6599\u5831\u4e2d\u771f\u6b63\u958b\u59cb\u5b58\u653e\u8cc7\u6599\u7684\u4f4d\u7f6e\u3002
\n\ud83d\udd18 \u670d\u52d9\u985e\u578b (type of service)\uff1a\u6a19\u8a18\u9700\u8981\u5ef6\u9072\u6642\u9593\u3001\u9ad8\u7522\u51fa\u7387\u6216\u53ef\u9760\u6027\u7684\u8cc7\u6599\u5831\u3002
\n\ud83d\udd18 \u8cc7\u6599\u5831\u9577\u5ea6 (datagram length)\uff1aIP\u8cc7\u6599\u5831\u7684\u7e3d\u9577\u5ea6 (\u6a19\u982d\u52a0\u4e0a\u8cc7\u6599)\u3002
\n\ud83d\udd18 \u8b58\u5225\u78bc (identifier)\u3001\u65d7\u6a19 (flag)\u3001\u5206\u6bb5\u504f\u79fb\u91cf (fragmentation offset)\uff1aIP \u5206\u6bb5\u7528\u3002
\n\ud83d\udd18 \u751f\u5b58\u671f (time-to-live)\uff1a\u78ba\u4fdd\u8cc7\u6599\u5831\u4e0d\u6703\u5728\u7db2\u8def\u4e2d\u7121\u7aae\u7684\u5faa\u74b0\u50b3\u9001\u3002\u4e00\u5177\u8def\u7531\u5668\u6240\u8655\u7406\u5f8c\uff0c\u9019\u500b\u6b04\u4f4d\u7684\u6578\u503c\u5c31\u6703\u6e1b 1\u3002\u5982\u679cTTL\u6b04\u4f4d\u503c\u6b78 0\uff0c\u9019\u4efd\u8cc7\u6599\u5831\u5c31\u6703\u88ab\u4e1f\u68c4\u3002
\n\ud83d\udd18 \u5354\u5b9a (protocol)\uff1a\u8cc7\u6599\u8981\u8f49\u4ea4\u7d66\u54ea\u500b\u7279\u5b9a\u7684\u50b3\u8f38\u5c64\u5354\u5b9a\u3002
\n\u2198\u6578\u503c 6 \u8f49\u4ea4\u7d66 TCP\uff0c\u6578\u503c 17 \u8f49\u4ea4\u7d66 UDP\u3002
\n\ud83d\udd18 \u6a19\u982d\u6aa2\u67e5\u548c (header checksum)\uff1a\u5075\u6e2c\u4f4d\u5143\u932f\u8aa4\u3002
\n\ud83d\udd18 \u4f86\u6e90\u7aef\u8207\u76ee\u7684\u7aef IP \u4f4d\u5740
\n\ud83d\udd18 \u9078\u7528\u6b04\u4f4d (options)
\n\ud83d\udd18 \u8cc7\u6599 (data) [\u8377\u8f09 (payload)]<\/p>\n

\ud83d\udcac IP \u8cc7\u6599\u5831\u7e3d\u5171\u6709 20 \u4f4d\u5143\u7d44\u7684\u6a19\u982d (\u5047\u8a2d\u6c92\u6709\u9078\u7528\u6b04\u4f4d)\u3002\u5982\u679c\u8cc7\u6599\u5831\u651c\u5e36\u7684\u662fTCP \u5340\u6bb5\uff0c\u5247\u6bcf\u4efd (\u672a\u5206\u6bb5\u7684) \u8cc7\u6599\u5831\u90fd\u6703\u651c\u5e36\u5171 40 \u4f4d\u5143\u7d44\u7684\u6a19\u982d (20 \u4f4d\u5143\u7d44\u7684IP \u6a19\u982d\uff0c\u52a0\u4e0a20 \u4f4d\u5143\u7d44\u7684TCP \u6a19\u982d)\uff0c\u518d\u52a0\u4e0a\u61c9\u7528\u5c64\u8a0a\u606f\u3002<\/p>\n

\ud83c\udf0f 4.4.2 IPv4 \u5b9a\u5740<\/p>\n

\ud83d\udd3a \u4e3b\u6a5f\u8ddf\u8def\u7531\u5668\u7684\u6bcf\u500b\u4ecb\u9762\u90fd\u5fc5\u9808\u64c1\u6709\u81ea\u5df1\u7684 IP \u4f4d\u5740\u3002
\n\ud83d\udd3a IP \u4f4d\u5740\u7684\u9577\u5ea6\u90fd\u662f 32 \u4f4d\u5143 (\u53734\u4f4d\u5143\u7d44)\uff0c\u56e0\u6b64\u7e3d\u5171\u6709 2^32 \u500b\u53ef\u80fd\u7684 IP \u4f4d\u5740\u3002
\n\ud83d\udd3a \u9644\u9ede\u5341\u9032\u4f4d\u8868\u793a\u6cd5 (dotted-decimal notation) [\u5982:192.168.1.1]
\n\ud83d\udd3a \u6bcf\u500b\u4ecb\u9762\u90fd\u5fc5\u9808\u64c1\u6709\u4e00\u500b\u5168\u4e16\u754c\u7368\u4e00\u7121\u4e8c\u7684 IP \u4f4d\u5740\u3002<\/p>\n

\ud83d\udd38 \u9023\u63a5\u4e86\u4e09\u500b\u4e3b\u6a5f\u4ecb\u9762\u4ee5\u53ca\u4e00\u500b\u8def\u7531\u5668\u4ecb\u9762\u7684\u7db2\u8def\uff0c\u5f62\u6210\u4e86\u4e00\u500b\u5b50\u7db2\u8def (subnet) \u3002
\n\ud83d\udd38 \u5b50\u7db2\u8def\u4e5f\u7a31\u70ba IP \u7db2\u8def\uff0c\u6216\u7c21\u7a31\u70ba\u7db2\u8def\u3002
\n\ud83d\udd38 \u7db2\u969b\u7db2\u8def\u7684\u4f4d\u5740\u5206\u914d\u7b56\u7565\uff0c\u7a31\u70ba\u7121\u5206\u7d1a\u8de8\u7db2\u57df\u7e5e\u9001 (Classless Interdomain Routing\uff0cCIDR\u2014\u5538\u505a\u300ccider\u300d)<\/p>\n

\ud83d\udd18 211.1.1.0\/24 \uff0c\u6a19\u8a18 \/24 \u6709\u6642\u7a31\u70ba\u5b50\u7db2\u8def\u906e\u7f69 (subnet mask)\uff0c\u8868\u793a\u662f\u9019\u500b 32 \u4f4d\u5143\u91cf\u503c\u6700\u5de6\u908a\u7684 24 \u4f4d\u5143\u5b9a\u7fa9\u4e86\u5b50\u7db2\u8def\u7684\u4f4d\u5740 (\u5740\u9996 (prefix) [ \u6216\u7db2\u8def\u5740\u9996 (network prefix)]\u3002
\n\u4efb\u4f55\u65b0\u9023\u63a5\u5230 211.1.1.0\/24 \u5b50\u7db2\u8def\u7684\u4e3b\u6a5f\uff0c\u90fd\u5177\u6709\u5f62\u5f0f\u70ba 211.1.1.xxx \u7684\u4f4d\u5740\u3002<\/p>\n

\ud83d\udcac \u63a1\u7528 CIDR \u4e4b\u524d\uff0cIP \u4f4d\u5740\u7db2\u8def\u90e8\u5206\u7684\u9577\u5ea6\u88ab\u9650\u5236\u70ba 8\u300116 \u621624 \u4f4d\u5143\uff0c\u9019\u7a2e\u5b9a\u5740\u65b9\u5f0f\u7a31\u70ba\u5206\u7d1a\u5b9a\u5740\u6cd5 (classful addressing)\uff0c\u5373\u5206\u70ba A \u7d1a\u3001B \u7d1a\u8207 C \u7d1a\u3002<\/p>\n

\ud83d\udd18 \u4e3b\u6a5f\u9001\u51fa\u76ee\u7684\u7aef\u4f4d\u5740\u70ba 255.255.255.255 \u27a1 \u5ee3\u64ad<\/p>\n

\ud83d\udd18 \u52d5\u614b\u4e3b\u6a5f\u914d\u7f6e\u5354\u5b9a(DHCP) \u27a1 \u81ea\u52d5\u53d6\u5f97 IP \u4f4d\u5740 \u27a1 \u96a8\u63d2\u5373\u7528\u5354\u5b9a (plug-and-play protocol)<\/p>\n

\ud83d\udd38 \u5c0d\u65b0\u5230\u4f86\u7684\u4e3b\u6a5f\u800c\u8a00\uff0cDHCP \u5354\u5b9a\u662f\u500b\u56db\u6b65\u9a5f\u7684\u7a0b\u5e8f\uff1a
\n1\ufe0f\u20e3 \u641c\u5c0b DHCP \u4f3a\u670d\u5668
\n2\ufe0f\u20e3 \u63d0\u4f9b DHCP \u4f3a\u670d\u5668
\n3\ufe0f\u20e3 DHCP \u8acb\u6c42
\n4\ufe0f\u20e3 DHCP ACK<\/p>\n

\ud83d\udd18 \u7db2\u8def\u4f4d\u5740\u8f49\u8b6f (network address translation\uff0cNAT)\uff1a\u4f4d\u5740\u7a7a\u959310.0.0.0\/8 \u662f\u4fdd\u7559\u7d66\u79c1\u4eba\u7db2\u8def\uff0c\u6216\u4f7f\u7528\u79c1\u4eba\u4f4d\u5740\u7684\u9818\u57df (realm)\uff0c\u53ea\u5c0d\u65bc\u5176\u5167\u90e8\u7684\u88dd\u7f6e\u6709\u610f\u7fa9\u3002
\n\ud83d\udd3aNAT \u8def\u7531\u5668\u4e0a\u4f7f\u7528 NAT \u8f49\u8b6f\u8868 (NAT translation table)\uff0c\u9664\u4e86 IP \u4f4d\u5740\u4e4b\u5916\uff0c\u6211\u5011\u4e5f\u6703\u5c07\u57e0\u865f\u52a0\u5165\u8868\u683c\u9805\u76ee\u4e2d\u3002<\/p>\n

\ud83c\udf0f 4.4.4 IPv6<\/p>\n

\ud83d\udd38 \u64f4\u5145\u7684\u5b9a\u5740\u80fd\u529b\uff1aIPv6 \u5c07 IP \u4f4d\u5740\u7684\u9577\u5ea6\u5f9e 32 \u4f4d\u5143\u589e\u52a0\u5230 128 \u4f4d\u5143\u3002
\n\ud83d\udd38 \u7cbe\u7c21\u5f8c\u7684 40 \u4f4d\u5143\u7d44\u56fa\u5b9a\u6a19\u982d\u3002
\n\ud83d\udd38 \u8cc7\u6599\u6d41\u6a19\u8a18\u8207\u512a\u5148\u6b0a\u3002<\/p>\n

\ud83d\udd18 IPv6 \u5b9a\u7fa9\u4e86\u4ee5\u4e0b\u6b04\u4f4d\uff1a
\n\u25ab \u7248\u672c (version)\u3002
\n\u25ab \u6d41\u91cf\u985e\u578b (traffic class)\u3002
\n\u25ab \u8cc7\u6599\u6d41\u6a19\u8a18 (flow label)\u3002
\n\u25ab \u8377\u8f09\u9577\u5ea6 (payload length)\u3002
\n\u25ab \u5167\u5c64\u6a19\u982d (next header)\u3002
\n\u25ab \u8e8d\u7a0b\u9650\u5236 (hop limit)\u3002
\n\u25ab \u4f86\u6e90\u7aef\u53ca\u76ee\u7684\u7aef\u4f4d\u5740 (source and destination addresses)\u3002
\n\u25ab \u8cc7\u6599 (data)\u3002<\/p>\n

\ud83d\udd18 IPv4 \u6709\uff0c\u4f46 IPv6 \u6c92\u6709\u7684\u6b04\u4f4d\uff1a
\n\u25ab \u5206\u6bb5 \/ \u91cd\u7d44 (Fragmentation\/Reassembly)\u3002
\n\u25ab \u6a19\u982d\u6aa2\u67e5\u548c (header checksum)\u3002
\n\u25ab \u9078\u7528\u6b04\u4f4d (options)\u3002<\/p>\n

\ud83d\udd38 \u5f9e IPv4 \u8f49\u63db\u6210 IPv6\uff1a\u96d9\u5806\u758a (dual-stack) \u548c \u901a\u9053\u65b9\u6848(tunneling) \u65b9\u6848\u3002<\/p>\n

\ud83c\udf0f 4.5 \u7e5e\u9001\u6f14\u7b97\u6cd5\uff1a\u5176\u6703\u627e\u5230\u4e00\u689d\u5f9e\u4f86\u6e90\u7aef\u8def\u7531\u5668\u5230\u76ee\u7684\u7aef\u8def\u7531\u5668\u7684\u300c\u826f\u597d\u300d\u8def\u5f91\u3002<\/p>\n

\ud83c\udf0f 4.5.1 \u9023\u7d50\u72c0\u614b (LS) \u7e5e\u9001\u6f14\u7b97\u6cd5\uff1a\u900f\u904e\u9023\u7d50\u72c0\u614b\u5ee3\u64ad (link-state broadcast) \u6f14\u7b97\u6cd5\u3002<\/p>\n

\ud83d\udd38 \u6240\u6709\u7684\u7bc0\u9ede\u90fd\u6703\u5c0d\u7db2\u8def\u64c1\u6709\u7d71\u4e00\u4e14\u5b8c\u6574\u7684\u89c0\u9ede\u3002\u5982\u6b64\u4e00\u4f86\u6bcf\u500b\u7bc0\u9ede\u90fd\u53ef\u4ee5\u57f7\u884c LS \u6f14\u7b97\u6cd5\uff0c\u4e26\u8a08\u7b97\u51fa\u8207\u5176\u4ed6\u6240\u6709\u7bc0\u9ede\u76f8\u540c\u7684\u4e00\u7d44\u6700\u5c0f\u6210\u672c\u8def\u5f91\u3002
\n\ud83d\udd3a \u9023\u7d50\u72c0\u614b\u6f14\u7b97\u6cd5\uff0c\u7a31\u70ba Dijkstra \u6f14\u7b97\u6cd5\u3002
\n\ud83d\udd38 Dijkstra \u6f14\u7b97\u6cd5\u6703\u8a08\u7b97\u51fa\u5f9e\u67d0\u500b\u7bc0\u9ede\u5230\u7db2\u8def\u4e2d\u5176\u5b83\u6240\u6709\u7bc0\u9ede\u7684\u6700\u5c0f\u6210\u672c\u8def\u5f91\u3002<\/p>\n

\ud83d\udcac \u907f\u514d\u81ea\u6211\u540c\u6b65\u5316\uff0c\u6703\u8b93\u6bcf\u5177\u8def\u7531\u5668\u90fd\u96a8\u6a5f\u9078\u64c7\u6642\u9593\u9001\u51fa\u9023\u7d50\u901a\u544a\u3002<\/p>\n

\ud83c\udf0f 4.5.2 \u8ddd\u96e2\u5411\u91cf (DV) \u7e5e\u9001\u6f14\u7b97\u6cd5 \uff1a\u662f\u4e00\u7a2e\u5faa\u74b0\u5f0f\u3001\u975e\u540c\u6b65\u3001\u5206\u6563\u5f0f\u7684\u6f14\u7b97\u6cd5\u3002<\/p>\n

\ud83d\udd38 \u5404\u7bc0\u9ede\u6703\u5f9e\u4e00\u6216\u591a\u500b\u76f4\u63a5\u76f8\u9023\u7684\u76f8\u9130\u7bc0\u9ede\u4e2d\u5f97\u5230\u4e00\u4e9b\u8cc7\u8a0a\u3002
\n\ud83d\udd38 \u5f9e\u76f8\u9130\u7bc0\u9ede\u63a5\u6536\u66f4\u65b0\u5f8c\u7684\u8ddd\u96e2\u5411\u91cf\u3001\u91cd\u65b0\u8a08\u7b97\u7e5e\u9001\u8868\u9805\u76ee\u3001\u901a\u77e5\u76f8\u9130\u7bc0\u9ede\u524d\u5f80\u67d0\u500b\u76ee\u7684\u7aef\u7684\u6700\u5c0f\u6210\u672c\u8def\u5f91\u7684\u6210\u672c\u6539\u8b8a\uff1b\u9019\u6574\u500b\u7a0b\u5e8f\u6703\u6301\u7e8c\u9032\u884c\uff0c\u76f4\u5230\u6c92\u6709\u66f4\u65b0\u8a0a\u606f\u9001\u51fa\u70ba\u6b62\u3002
\n\ud83d\udd3a \u7279\u6b8a\u8ff4\u5708\u60c5\u5883\uff0c\u53ef\u4ee5\u4f7f\u7528\u7a31\u70ba\u6291\u5236\u6027\u53cd\u8f49 (poisoned reverse) \u7684\u6280\u5de7\u907f\u514d\u3002<\/p>\n

\ud83d\udcac \u5176\u5b83\u7e5e\u9001\u6f14\u7b97\u6cd5 \uff1aLS \u548c DV \u6f14\u7b97\u6cd5\u4e0d\u50c5\u5728\u5be6\u4f5c\u4e0a\u88ab\u5ee3\u6cdb\u4f7f\u7528\uff1b\u57fa\u672c\u4e0a\uff0c\u5b83\u5011\u662f\u4eca\u65e5\u552f\u4e8c\u88ab\u5be6\u969b\u4f7f\u7528\u5728\u7db2\u969b\u7db2\u8def\u4e2d\u7684\u7e5e\u9001\u6f14\u7b97\u6cd5\u3002<\/p>\n

\ud83c\udf0f 4.5.3 \u968e\u5c64\u5f0f\u7e5e\u9001<\/p>\n

\ud83d\udd18 \u81f3\u5c11\u5728\u5169\u9805\u91cd\u8981\u539f\u56e0\u4e0a\uff0c\u6709\u9ede\u5c07\u4e8b\u60c5\u7c21\u55ae\u5316\u4e86\uff1a
\n\ud83d\udd38 \u898f\u6a21\uff1a\u771f\u5be6\u60c5\u6cc1\u8def\u7531\u5668\u7684\u6578\u76ee\u662f\u5f88\u591a\u7684\u3002
\n\ud83d\udd38 \u7ba1\u7406\u81ea\u6cbb\u6b0a\uff1a\u7d44\u7e54\u61c9\u8a72\u8981\u80fd\u5920\u4f9d\u81ea\u5df1\u7684\u610f\u9858\u904b\u4f5c\u4e26\u7ba1\u7406\u81ea\u5df1\u7684\u7db2\u8def\uff0c\u540c\u6642\u4ecd\u7136\u80fd\u5920\u5c07\u81ea\u5df1\u7684\u7db2\u8def\u9023\u63a5\u5230\u5916\u754c\u7684\u7db2\u8def\u3002<\/p>\n

\u27a1 \u89e3\u6c7a\u65b9\u6848\uff1a\u81ea\u6cbb\u7cfb\u7d71 (autonomous systems\uff0cAS)
\n\ud83d\udd3a \u81ea\u6cbb\u7cfb\u7d71\u5167\u90e8\u7e5e\u9001\u5354\u5b9a (intra-autonomous system routing protocol)
\n\ud83d\udd3a \u5c0d AS \u5916\u9700\u8981\u9598\u9053\u8def\u7531\u5668 (gateway router)<\/p>\n

\ud83d\udd38 \u7db2\u969b\u7db2\u8def\u4e2d\u6240\u6709\u7684 AS \u90fd\u6703\u57f7\u884c\u76f8\u540c\u7684\u8de8 AS \u7e5e\u9001\u5354\u5b9a\uff0c\u7a31\u70ba BGP4\u3002<\/p>\n

\ud83c\udf0f 4.6.1 \u7db2\u969b\u7db2\u8def\u7684 AS \u5167\u90e8\u7e5e\u9001\uff1aRIP<\/p>\n

\ud83d\udd38 RIP \u662f\u4e00\u7a2e\u8ddd\u96e2\u5411\u91cf\u5354\u5b9a\uff0c\u64cd\u4f5c\u65b9\u5f0f\u975e\u5e38\u63a5\u8fd1\u7406\u60f3\u5316 DV \u5354\u5b9a\u3002
\n\ud83d\udd38 \u8e8d\u7a0b\u8a08\u6578 (hop count) \u4f5c\u70ba\u6210\u672c\u7684\u8a08\u91cf\uff1b\u4e5f\u5c31\u662f\u8aaa\uff0c\u6bcf\u9053\u9023\u7d50\u7684\u6210\u672c\u7686\u70ba 1\u3002
\n\ud83d\udd38 \u6bcf\u53f0\u8def\u7531\u5668\u90fd\u7dad\u8b77\u8457\u4e00\u4efd\u7a31\u70ba\u7e5e\u9001\u8868\u7684 RIP \u8868\u683c\u3002
\n\ud83d\udd38 \u8def\u5f91\u7684\u6700\u5927\u6210\u672c\u88ab\u9650\u5236\u70ba 15\uff0c\u9019\u9650\u5236\u4e86RIP \u53ea\u80fd\u5920\u7528\u5728\u76f4\u5f91\u5c11\u65bc 15 \u6bb5\u8e8d\u7a0b\u7684\u81ea\u6cbb\u7cfb\u7d71\u4e2d\u3002
\n\ud83d\udd38 RIP \u4e2d\uff0c\u76f8\u9130\u7bc0\u9ede\u9593\u5927\u7d04\u6bcf\u9694 30 \u79d2\u5c31\u6703\u4f7f\u7528 RIP \u56de\u61c9\u8a0a\u606f (RIP response message) \u300cRIP\u901a\u544a (RIP advertisement)\u300d \u4f86\u4ea4\u63db\u7e5e\u9001\u66f4\u65b0\u8a0a\u606f\u3002
\n\ud83d\udd3a \u8def\u7531\u5668\u7121\u6cd5\u5728\u81f3\u5c11\u6bcf 180 \u79d2\u5167\u6536\u5230\u4f86\u81ea\u5176\u76f8\u9130\u7bc0\u9ede\u7684\u901a\u544a\uff0c\u4fbf\u6703\u8a8d\u70ba\u9019\u500b\u76f8\u9130\u7bc0\u9ede\u5df2\u7121\u6cd5\u62b5\u9054\u3002<\/p>\n

\ud83c\udf0f 4.6.2 \u7db2\u969b\u7db2\u8def\u7684AS \u5167\u90e8\u7e5e\u9001\uff1aOSPF<\/p>\n

\ud83d\udd38 \u50cf RIP \u4e00\u6a23\uff0cOSPF \u7e5e\u9001\u4e5f\u88ab\u5ee3\u6cdb\u4f7f\u7528\u5728\u7db2\u969b\u7db2\u8def\u7684 AS \u5167\u90e8\u7e5e\u9001\u4e2d\u3002
\n\ud83d\udd38 \u662f\u4e00\u7a2e\u9023\u7d50\u72c0\u614b\u5354\u5b9a\uff0c\u904b\u7528\u7684\u662f\u9023\u7d50\u72c0\u614b\u8cc7\u8a0a\u7684\u6563\u64ad\u8207 Dijkstra \u6700\u5c0f\u6210\u672c\u8def\u5f91\u6f14\u7b97\u6cd5\u3002
\n\ud83d\udd38 \u8def\u7531\u5668\u6703\u5efa\u69cb\u51fa\u6574\u500b\u81ea\u6cbb\u7cfb\u7d71\u7684\u5b8c\u6574\u62d3\u6a38\u5730\u5716\u3002
\n\ud83d\udd38 \u8def\u7531\u5668\u6703\u5728\u672c\u6a5f\u57f7\u884c Dijkstra \u6700\u77ed\u8def\u5f91\u6f14\u7b97\u6cd5\uff0c\u4ee5\u5224\u65b7\u51fa\u4ee5\u81ea\u5df1\u70ba\u6839\u7bc0\u9ede\uff0c\u524d\u5f80\u6240\u6709\u5b50\u7db2\u8def\u7684\u6700\u77ed\u8def\u5f91\u6a39\u3002
\n\ud83d\udd38 \u8def\u7531\u5668\u6703\u5ee3\u64ad\u7e5e\u9001\u8cc7\u8a0a\u7d66\u81ea\u6cbb\u7cfb\u7d71\u5167\u90e8\u5176\u5b83\u6240\u6709\u7684\u8def\u7531\u5668\u3002<\/p>\n

\ud83d\udd18 OSPF \u6240\u5be6\u4f5c\u7684\u4e00\u4e9b\u9032\u968e\u7279\u6027\u5305\u62ec\u4ee5\u4e0b\uff1a
\n\u25ab \u5b89\u5168\u6027\u3002
\n\u25ab \u591a\u689d\u6210\u672c\u76f8\u540c\u7684\u8def\u5f91\u3002
\n\u25ab \u5c0d\u65bc\u55ae\u64ad\u8207\u7fa4\u64ad\u7e5e\u9001\u7684\u6574\u5408\u652f\u63f4\u3002
\n\u25ab \u5728\u55ae\u4e00\u7e5e\u9001\u7db2\u57df\u4e2d\u652f\u63f4\u968e\u5c64\u5f0f\u67b6\u69cb\u3002<\/p>\n

\ud83d\udd38 \u6709\u4e00\u6216\u591a\u53f0\u5340\u57df\u908a\u5883\u8def\u7531\u5668 (area border router) \u8ca0\u8cac\u5c07\u5c01\u5305\u7e5e\u9001\u5230\u5340\u57df\u4e4b\u5916\u3002
\n\ud83d\udd38 AS \u5167\u6703\u6709\u552f\u4e00\u4e00\u500b OSPF \u5340\u57df\u88ab\u8a2d\u5b9a\u70ba\u4e3b\u5e79 (backbone) \u5340\u57df\uff0c\u8ca0\u8cacAS \u7684\u5176\u4ed6\u5340\u57df\u4e4b\u9593\u7e5e\u9001\u8cc7\u6599\u6d41\u3002<\/p>\n

\ud83c\udf0f 4.6.3 \u8de8AS \u7e5e\u9001\uff1aBGP<\/p>\n

\ud83d\udd38 \u908a\u5883\u9598\u9053\u5354\u5b9a (Border Gateway Protocol) \u662f\u4eca\u65e5\u7db2\u969b\u7db2\u8def\u4e2d\u8de8 AS \u7e5e\u9001\u5354\u5b9a\u7684\u5be6\u8cea\u6a19\u6e96\u3002
\n\ud83d\udd38 \u5b83\u901a\u5e38\u88ab\u7a31\u70ba BGP4\uff0c\u6216\u7c21\u7a31 BGP\u3002
\n\ud83d\udd38 \u5404\u5c0d\u8def\u7531\u5668\u6703\u900f\u904e\u4f7f\u7528\u57e0\u865f 179 \u7684\u534a\u6c38\u4e45\u6027 TCP \u9023\u7dda\u4f86\u4ea4\u63db\u7e5e\u9001\u8cc7\u8a0a\u3002
\n\ud83d\udd38 \u9023\u7dda\u5169\u7aef\u7684\u8def\u7531\u5668\u7a31\u70ba BGP \u5c0d\u7b49\u9ede (BGP peers)\u3002
\n\ud83d\udd38 TCP \u9023\u7dda\u52a0\u4e0a\u6240\u6709\u900f\u904e\u8a72\u7b46\u9023\u7dda\u50b3\u9001\u7684 BGP \u8a0a\u606f\uff0c\u5247\u7a31\u70ba BGP \u6703\u8ac7 (BGP session)\u3002
\n\ud83d\udd39 \u8de8\u8d8a\u5169\u7d44 AS \u7684 BGP \u6703\u8ac7\u7a31\u70ba\u5916\u90e8 BGP \u6703\u8ac7 [external BGP (eBGP) session]\u3002
\n\ud83d\udd39 \u540c\u7d44 AS \u5167\u90e8\u7684\u8def\u7531\u5668\u4e4b\u9593\u7684BGP \u6703\u8ac7\u5247\u7a31\u70ba\u5167\u90e8 BGP \u6703\u8ac7 (internal BGP\uff0ciBGP session)\u3002
\n\ud83d\udcac \u81ea\u6cbb\u7cfb\u7d71\u662f\u7531\u5404\u81ea\u5728\u4e16\u4e0a\u7368\u4e00\u7121\u4e8c\u7684\u81ea\u6cbb\u7cfb\u7d71\u7de8\u865f (autonomous system number\uff0cASN) \u4f86\u52a0\u4ee5\u8b58\u5225\u3002
\n\ud83d\udcac \u5728BGP \u8853\u8a9e\u4e2d\uff0c\u5740\u9996\u52a0\u4e0a\u5176\u5c6c\u6027\uff0c\u4fbf\u7a31\u70ba\u8def\u7531 (route)\u3002<\/p>

\n