{"id":240,"date":"2022-05-31T14:06:15","date_gmt":"2022-05-31T06:06:15","guid":{"rendered":"http:\/\/blog.kijk.top\/?p=240"},"modified":"2022-05-31T14:23:38","modified_gmt":"2022-05-31T06:23:38","slug":"tcp-%e9%87%8d%e4%bc%a0","status":"publish","type":"post","link":"http:\/\/blog.kijk.top\/?p=240","title":{"rendered":"TCP \u91cd\u4f20"},"content":{"rendered":"\n

\u8f6c\u8f7d\u4e8e\uff1ahttps:\/\/www.cnblogs.com\/xiaolincoding\/p\/12732052.html<\/p>\n\n\n\n

\u539f\u4f5c\u8005\u5199\u5f97\u5f88\u8be6\u7ec6\uff0c\u53d7\u76ca\u532a\u6d45\uff0c\u5728\u6b64\u7531\u8877\u611f\u8c22\uff01<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

\u91cd\u4f20\u673a\u5236<\/h2>\n\n\n\n

TCP \u5b9e\u73b0\u53ef\u9760\u4f20\u8f93\u7684\u65b9\u5f0f\u4e4b\u4e00\uff0c\u662f\u901a\u8fc7\u5e8f\u5217\u53f7\u4e0e\u786e\u8ba4\u5e94\u7b54\u3002<\/p>\n\n\n\n

\u5728 TCP \u4e2d\uff0c\u5f53\u53d1\u9001\u7aef\u7684\u6570\u636e\u5230\u8fbe\u63a5\u6536\u4e3b\u673a\u65f6\uff0c\u63a5\u6536\u7aef\u4e3b\u673a\u4f1a\u8fd4\u56de\u4e00\u4e2a\u786e\u8ba4\u5e94\u7b54\u6d88\u606f\uff0c\u8868\u793a\u5df2\u6536\u5230\u6d88\u606f\u3002<\/p>\n\n\n\n

<\/p>\n\n\n\n

\"\"
\u6b63\u5e38\u7684\u6570\u636e\u4f20\u8f93<\/figcaption><\/figure>\n\n\n\n

<\/p>\n\n\n\n

\u4f46\u5728\u9519\u7efc\u590d\u6742\u7684\u7f51\u7edc\uff0c\u5e76\u4e0d\u4e00\u5b9a\u80fd\u5982\u4e0a\u56fe\u90a3\u4e48\u987a\u5229\u80fd\u6b63\u5e38\u7684\u6570\u636e\u4f20\u8f93\uff0c\u4e07\u4e00\u6570\u636e\u5728\u4f20\u8f93\u8fc7\u7a0b\u4e2d\u4e22\u5931\u4e86\u5462\uff1f<\/p>\n\n\n\n

\u6240\u4ee5 TCP \u9488\u5bf9\u6570\u636e\u5305\u4e22\u5931\u7684\u60c5\u51b5\uff0c\u4f1a\u7528\u91cd\u4f20\u673a\u5236<\/strong>\u89e3\u51b3\u3002<\/p>\n\n\n\n

\u63a5\u4e0b\u6765\u8bf4\u8bf4\u5e38\u89c1\u7684\u91cd\u4f20\u673a\u5236\uff1a<\/p>\n\n\n\n

  • \u8d85\u65f6\u91cd\u4f20<\/li>
  • \u5feb\u901f\u91cd\u4f20<\/li>
  • SACK<\/li>
  • D-SACK<\/li><\/ul>\n\n\n\n

    \u8d85\u65f6\u91cd\u4f20<\/h2>\n\n\n\n

    \u91cd\u4f20\u673a\u5236\u7684\u5176\u4e2d\u4e00\u4e2a\u65b9\u5f0f\uff0c\u5c31\u662f\u5728\u53d1\u9001\u6570\u636e\u65f6\uff0c\u8bbe\u5b9a\u4e00\u4e2a\u5b9a\u65f6\u5668\uff0c\u5f53\u8d85\u8fc7\u6307\u5b9a\u7684\u65f6\u95f4\u540e\uff0c\u6ca1\u6709\u6536\u5230\u5bf9\u65b9\u7684 ACK<\/code> \u786e\u8ba4\u5e94\u7b54\u62a5\u6587\uff0c\u5c31\u4f1a\u91cd\u53d1\u8be5\u6570\u636e\uff0c\u4e5f\u5c31\u662f\u6211\u4eec\u5e38\u8bf4\u7684\u8d85\u65f6\u91cd\u4f20<\/strong>\u3002<\/p>\n\n\n\n

    TCP \u4f1a\u5728\u4ee5\u4e0b\u4e24\u79cd\u60c5\u51b5\u53d1\u751f\u8d85\u65f6\u91cd\u4f20\uff1a<\/p>\n\n\n\n

    • \u6570\u636e\u5305\u4e22\u5931<\/li>
    • \u786e\u8ba4\u5e94\u7b54\u4e22\u5931<\/li><\/ul>\n\n\n\n
      \"\"
      \u8d85\u65f6\u91cd\u4f20\u7684\u4e24\u79cd\u60c5\u51b5<\/figcaption><\/figure>\n\n\n\n

      <\/p>\n\n\n\n

      \n
      \n
      \n

      \u8d85\u65f6\u65f6\u95f4\u5e94\u8be5\u8bbe\u7f6e\u4e3a\u591a\u5c11\u5462\uff1f<\/p><\/blockquote>\n<\/div><\/div>\n<\/div>\n<\/div>\n\n\n\n

      \u6211\u4eec\u5148\u6765\u4e86\u89e3\u4e00\u4e0b\u4ec0\u4e48\u662f RTT<\/code>\uff08Round-Trip Time \u5f80\u8fd4\u65f6\u5ef6\uff09\uff0c\u4ece\u4e0b\u56fe\u6211\u4eec\u5c31\u53ef\u4ee5\u77e5\u9053\uff1a<\/p>\n\n\n\n

      \"\"
      RTT<\/figcaption><\/figure>\n\n\n\n

      <\/p>\n\n\n\n

      <\/p>\n\n\n\n

      RTT<\/code> \u5c31\u662f\u6570\u636e\u4ece\u7f51\u7edc\u4e00\u7aef\u4f20\u9001\u5230\u53e6\u4e00\u7aef\u6240\u9700\u7684\u65f6\u95f4<\/strong>\uff0c\u4e5f\u5c31\u662f\u5305\u7684\u5f80\u8fd4\u65f6\u95f4\u3002<\/p>\n\n\n\n

      \u8d85\u65f6\u91cd\u4f20\u65f6\u95f4\u662f\u4ee5 RTO<\/code> \uff08Retransmission Timeout \u8d85\u65f6\u91cd\u4f20\u65f6\u95f4\uff09\u8868\u793a\u3002<\/p>\n\n\n\n

      \u5047\u8bbe\u5728\u91cd\u4f20\u7684\u60c5\u51b5\u4e0b\uff0c\u8d85\u65f6\u65f6\u95f4 RTO<\/code> \u300c\u8f83\u957f\u6216\u8f83\u77ed\u300d\u65f6\uff0c\u4f1a\u53d1\u751f\u4ec0\u4e48\u4e8b\u60c5\u5462\uff1f<\/p>\n\n\n\n

      \"\"
      \u8d85\u65f6\u65f6\u95f4\u8f83\u957f\u4e0e\u8f83\u77ed<\/figcaption><\/figure>\n\n\n\n

      <\/p>\n\n\n\n

      \u4e0a\u56fe\u4e2d\u6709\u4e24\u79cd\u8d85\u65f6\u65f6\u95f4\u4e0d\u540c\u7684\u60c5\u51b5\uff1a<\/p>\n\n\n\n

      • \u5f53\u8d85\u65f6\u65f6\u95f4 RTO \u8f83\u5927<\/strong>\u65f6\uff0c\u91cd\u53d1\u5c31\u6162\uff0c\u4e22\u4e86\u8001\u534a\u5929\u624d\u91cd\u53d1\uff0c\u6ca1\u6709\u6548\u7387\uff0c\u6027\u80fd\u5dee\uff1b<\/li>
      • \u5f53\u8d85\u65f6\u65f6\u95f4 RTO \u8f83\u5c0f<\/strong>\u65f6\uff0c\u4f1a\u5bfc\u81f4\u53ef\u80fd\u5e76\u6ca1\u6709\u4e22\u5c31\u91cd\u53d1\uff0c\u4e8e\u662f\u91cd\u53d1\u7684\u5c31\u5feb\uff0c\u4f1a\u589e\u52a0\u7f51\u7edc\u62e5\u585e\uff0c\u5bfc\u81f4\u66f4\u591a\u7684\u8d85\u65f6\uff0c\u66f4\u591a\u7684\u8d85\u65f6\u5bfc\u81f4\u66f4\u591a\u7684\u91cd\u53d1\u3002<\/li><\/ul>\n\n\n\n

        \u7cbe\u786e\u7684\u6d4b\u91cf\u8d85\u65f6\u65f6\u95f4 RTO<\/code> \u7684\u503c\u662f\u975e\u5e38\u91cd\u8981\u7684\uff0c\u8fd9\u53ef\u8ba9\u6211\u4eec\u7684\u91cd\u4f20\u673a\u5236\u66f4\u9ad8\u6548\u3002<\/p>\n\n\n\n

        \u6839\u636e\u4e0a\u8ff0\u7684\u4e24\u79cd\u60c5\u51b5\uff0c\u6211\u4eec\u53ef\u4ee5\u5f97\u77e5\uff0c\u8d85\u65f6\u91cd\u4f20\u65f6\u95f4 RTO \u7684\u503c\u5e94\u8be5\u7565\u5927\u4e8e\u62a5\u6587\u5f80\u8fd4 RTT \u7684\u503c<\/strong>\u3002<\/p>\n\n\n\n

        \"\"
        RTO \u5e94\u7565\u5927\u4e8e RTT<\/figcaption><\/figure>\n\n\n\n

        <\/p>\n\n\n\n

        \u81f3\u6b64\uff0c\u53ef\u80fd\u5927\u5bb6\u89c9\u5f97\u8d85\u65f6\u91cd\u4f20\u65f6\u95f4 RTO<\/code> \u7684\u503c\u8ba1\u7b97\uff0c\u4e5f\u4e0d\u662f\u5f88\u590d\u6742\u561b\u3002<\/p>\n\n\n\n

        \u597d\u50cf\u5c31\u662f\u5728\u53d1\u9001\u7aef\u53d1\u5305\u65f6\u8bb0\u4e0b t0<\/code> \uff0c\u7136\u540e\u63a5\u6536\u7aef\u518d\u628a\u8fd9\u4e2a ack<\/code> \u56de\u6765\u65f6\u518d\u8bb0\u4e00\u4e2a t1<\/code>\uff0c\u4e8e\u662f RTT = t1 \u2013 t0<\/code>\u3002\u6ca1\u90a3\u4e48\u7b80\u5355\uff0c\u8fd9\u53ea\u662f\u4e00\u4e2a\u91c7\u6837\uff0c\u4e0d\u80fd\u4ee3\u8868\u666e\u904d\u60c5\u51b5<\/strong>\u3002<\/p>\n\n\n\n

        \u5b9e\u9645\u4e0a\u300c\u62a5\u6587\u5f80\u8fd4 RTT \u7684\u503c\u300d\u662f\u7ecf\u5e38\u53d8\u5316\u7684\uff0c\u56e0\u4e3a\u6211\u4eec\u7684\u7f51\u7edc\u4e5f\u662f\u65f6\u5e38\u53d8\u5316\u7684\u3002\u4e5f\u5c31\u56e0\u4e3a\u300c\u62a5\u6587\u5f80\u8fd4 RTT \u7684\u503c\u300d \u662f\u7ecf\u5e38\u6ce2\u52a8\u53d8\u5316\u7684\uff0c\u6240\u4ee5\u300c\u8d85\u65f6\u91cd\u4f20\u65f6\u95f4 RTO \u7684\u503c\u300d\u5e94\u8be5\u662f\u4e00\u4e2a\u52a8\u6001\u53d8\u5316\u7684\u503c<\/strong>\u3002<\/p>\n\n\n\n

        \u6211\u4eec\u6765\u770b\u770b Linux \u662f\u5982\u4f55\u8ba1\u7b97 RTO<\/code> \u7684\u5462\uff1f<\/p>\n\n\n\n

        \u4f30\u8ba1\u5f80\u8fd4\u65f6\u95f4\uff0c\u901a\u5e38\u9700\u8981\u91c7\u6837\u4ee5\u4e0b\u4e24\u4e2a\uff1a<\/p>\n\n\n\n

        • \u9700\u8981 TCP \u901a\u8fc7\u91c7\u6837 RTT \u7684\u65f6\u95f4\uff0c\u7136\u540e\u8fdb\u884c\u52a0\u6743\u5e73\u5747\uff0c\u7b97\u51fa\u4e00\u4e2a\u5e73\u6ed1 RTT \u7684\u503c\uff0c\u800c\u4e14\u8fd9\u4e2a\u503c\u8fd8\u662f\u8981\u4e0d\u65ad\u53d8\u5316\u7684\uff0c\u56e0\u4e3a\u7f51\u7edc\u72b6\u51b5\u4e0d\u65ad\u5730\u53d8\u5316\u3002<\/li>
        • \u9664\u4e86\u91c7\u6837 RTT\uff0c\u8fd8\u8981\u91c7\u6837 RTT \u7684\u6ce2\u52a8\u8303\u56f4\uff0c\u8fd9\u6837\u5c31\u907f\u514d\u5982\u679c RTT \u6709\u4e00\u4e2a\u5927\u7684\u6ce2\u52a8\u7684\u8bdd\uff0c\u5f88\u96be\u88ab\u53d1\u73b0\u7684\u60c5\u51b5\u3002<\/li><\/ul>\n\n\n\n

          RFC6289 \u5efa\u8bae\u4f7f\u7528\u4ee5\u4e0b\u7684\u516c\u5f0f\u8ba1\u7b97 RTO\uff1a<\/p>\n\n\n\n

          \"\"
          RFC6289 \u5efa\u8bae\u7684 RTO \u8ba1\u7b97<\/figcaption><\/figure>\n\n\n\n

          <\/p>\n\n\n\n

          \u5176\u4e2d SRTT<\/code> \u662f\u8ba1\u7b97\u5e73\u6ed1\u7684RTT \uff0cDevRTR<\/code> \u662f\u8ba1\u7b97\u5e73\u6ed1\u7684RTT \u4e0e \u6700\u65b0 RTT \u7684\u5dee\u8ddd\u3002<\/p>\n\n\n\n

          \u5728 Linux \u4e0b\uff0c\u03b1 = 0.125\uff0c\u03b2 = 0.25\uff0c \u03bc = 1\uff0c\u2202 = 4<\/strong>\u3002\u522b\u95ee\u600e\u4e48\u6765\u7684\uff0c\u95ee\u5c31\u662f\u5927\u91cf\u5b9e\u9a8c\u4e2d\u8c03\u51fa\u6765\u7684\u3002<\/p>\n\n\n\n

          \u5982\u679c\u8d85\u65f6\u91cd\u53d1\u7684\u6570\u636e\uff0c\u518d\u6b21\u8d85\u65f6\u7684\u65f6\u5019\uff0c\u53c8\u9700\u8981\u91cd\u4f20\u7684\u65f6\u5019\uff0cTCP \u7684\u7b56\u7565\u662f\u8d85\u65f6\u95f4\u9694\u52a0\u500d\u3002<\/strong><\/p>\n\n\n\n

          \u4e5f\u5c31\u662f\u6bcf\u5f53\u9047\u5230\u4e00\u6b21\u8d85\u65f6\u91cd\u4f20\u7684\u65f6\u5019\uff0c\u90fd\u4f1a\u5c06\u4e0b\u4e00\u6b21\u8d85\u65f6\u65f6\u95f4\u95f4\u9694\u8bbe\u4e3a\u5148\u524d\u503c\u7684\u4e24\u500d\u3002\u4e24\u6b21\u8d85\u65f6\uff0c\u5c31\u8bf4\u660e\u7f51\u7edc\u73af\u5883\u5dee\uff0c\u4e0d\u5b9c\u9891\u7e41\u53cd\u590d\u53d1\u9001\u3002<\/strong><\/p>\n\n\n\n

          \u8d85\u65f6\u89e6\u53d1\u91cd\u4f20\u5b58\u5728\u7684\u95ee\u9898\u662f\uff0c\u8d85\u65f6\u5468\u671f\u53ef\u80fd\u76f8\u5bf9\u8f83\u957f\u3002\u90a3\u662f\u4e0d\u662f\u53ef\u4ee5\u6709\u66f4\u5feb\u7684\u65b9\u5f0f\u5462\uff1f<\/p>\n\n\n\n

          \u4e8e\u662f\u5c31\u53ef\u4ee5\u7528\u300c\u5feb\u901f\u91cd\u4f20\u300d\u673a\u5236\u6765\u89e3\u51b3\u8d85\u65f6\u91cd\u53d1\u7684\u65f6\u95f4\u7b49\u5f85\u3002<\/p>\n\n\n\n

          <\/p>\n\n\n\n

          \u5feb\u901f\u91cd\u4f20<\/h2>\n\n\n\n

          TCP \u8fd8\u6709\u53e6\u5916\u4e00\u79cd\u5feb\u901f\u91cd\u4f20\uff08Fast Retransmit\uff09\u673a\u5236<\/strong>\uff0c\u5b83\u4e0d\u4ee5\u65f6\u95f4\u4e3a\u9a71\u52a8\uff0c\u800c\u662f\u4ee5\u6570\u636e\u9a71\u52a8\u91cd\u4f20<\/strong>\u3002<\/p>\n\n\n\n

          \u5feb\u901f\u91cd\u4f20\u673a\u5236\uff0c\u662f\u5982\u4f55\u5de5\u4f5c\u7684\u5462\uff1f\u5176\u5b9e\u5f88\u7b80\u5355\uff0c\u4e00\u56fe\u80dc\u5343\u8a00\u3002<\/p>\n\n\n\n

          \"\"
          \u5feb\u901f\u91cd\u4f20\u673a\u5236<\/figcaption><\/figure>\n\n\n\n

          <\/p>\n\n\n\n

          \u5728\u4e0a\u56fe\uff0c\u53d1\u9001\u65b9\u53d1\u51fa\u4e86 1\uff0c2\uff0c3\uff0c4\uff0c5 \u4efd\u6570\u636e\uff1a<\/p>\n\n\n\n

          • \u7b2c\u4e00\u4efd Seq1 \u5148\u9001\u5230\u4e86\uff0c\u4e8e\u662f\u5c31 Ack \u56de 2\uff1b<\/li>
          • \u7ed3\u679c Seq2 \u56e0\u4e3a\u67d0\u4e9b\u539f\u56e0\u6ca1\u6536\u5230\uff0cSeq3 \u5230\u8fbe\u4e86\uff0c\u4e8e\u662f\u8fd8\u662f Ack \u56de 2\uff1b<\/li>
          • \u540e\u9762\u7684 Seq4 \u548c Seq5 \u90fd\u5230\u4e86\uff0c\u4f46\u8fd8\u662f Ack \u56de 2\uff0c\u56e0\u4e3a Seq2 \u8fd8\u662f\u6ca1\u6709\u6536\u5230\uff1b<\/li>
          • \u53d1\u9001\u7aef\u6536\u5230\u4e86\u4e09\u4e2a Ack = 2 \u7684\u786e\u8ba4\uff0c\u77e5\u9053\u4e86 Seq2 \u8fd8\u6ca1\u6709\u6536\u5230\uff0c\u5c31\u4f1a\u5728\u5b9a\u65f6\u5668\u8fc7\u671f\u4e4b\u524d\uff0c\u91cd\u4f20\u4e22\u5931\u7684 Seq2\u3002<\/strong><\/li>
          • \u6700\u540e\uff0c\u6536\u5230\u4e86 Seq2\uff0c\u6b64\u65f6\u56e0\u4e3a Seq3\uff0cSeq4\uff0cSeq5 \u90fd\u6536\u5230\u4e86\uff0c\u4e8e\u662f Ack \u56de 6 \u3002<\/li><\/ul>\n\n\n\n

            \u6240\u4ee5\uff0c\u5feb\u901f\u91cd\u4f20\u7684\u5de5\u4f5c\u65b9\u5f0f\u662f\u5f53\u6536\u5230\u4e09\u4e2a\u76f8\u540c\u7684 ACK \u62a5\u6587\u65f6\uff0c\u4f1a\u5728\u5b9a\u65f6\u5668\u8fc7\u671f\u4e4b\u524d\uff0c\u91cd\u4f20\u4e22\u5931\u7684\u62a5\u6587\u6bb5\u3002<\/p>\n\n\n\n

            \u5feb\u901f\u91cd\u4f20\u673a\u5236\u53ea\u89e3\u51b3\u4e86\u4e00\u4e2a\u95ee\u9898\uff0c\u5c31\u662f\u8d85\u65f6\u65f6\u95f4\u7684\u95ee\u9898\uff0c\u4f46\u662f\u5b83\u4f9d\u7136\u9762\u4e34\u7740\u53e6\u5916\u4e00\u4e2a\u95ee\u9898\u3002\u5c31\u662f\u91cd\u4f20\u7684\u65f6\u5019\uff0c\u662f\u91cd\u4f20\u4e4b\u524d\u7684\u4e00\u4e2a\uff0c\u8fd8\u662f\u91cd\u4f20\u6240\u6709\u7684\u95ee\u9898\u3002<\/strong><\/p>\n\n\n\n

            \u6bd4\u5982\u5bf9\u4e8e\u4e0a\u9762\u7684\u4f8b\u5b50\uff0c\u662f\u91cd\u4f20 Seq2 \u5462\uff1f\u8fd8\u662f\u91cd\u4f20 Seq2\u3001Seq3\u3001Seq4\u3001Seq5 \u5462\uff1f\u56e0\u4e3a\u53d1\u9001\u7aef\u5e76\u4e0d\u6e05\u695a\u8fd9\u8fde\u7eed\u7684\u4e09\u4e2a Ack 2 \u662f\u8c01\u4f20\u56de\u6765\u7684\u3002<\/p>\n\n\n\n

            \u6839\u636e TCP \u4e0d\u540c\u7684\u5b9e\u73b0\uff0c\u4ee5\u4e0a\u4e24\u79cd\u60c5\u51b5\u90fd\u662f\u6709\u53ef\u80fd\u7684\u3002\u53ef\u89c1\uff0c\u8fd9\u662f\u4e00\u628a\u53cc\u5203\u5251\u3002<\/p>\n\n\n\n

            \u4e3a\u4e86\u89e3\u51b3\u4e0d\u77e5\u9053\u8be5\u91cd\u4f20\u54ea\u4e9b TCP \u62a5\u6587\uff0c\u4e8e\u662f\u5c31\u6709 SACK<\/code> \u65b9\u6cd5\u3002<\/p>\n\n\n\n

            SACK \u65b9\u6cd5<\/h2>\n\n\n\n

            \u8fd8\u6709\u4e00\u79cd\u5b9e\u73b0\u91cd\u4f20\u673a\u5236\u7684\u65b9\u5f0f\u53eb\uff1aSACK<\/code>\uff08 Selective Acknowledgment \u9009\u62e9\u6027\u786e\u8ba4\uff09\u3002<\/p>\n\n\n\n

            \u8fd9\u79cd\u65b9\u5f0f\u9700\u8981\u5728 TCP \u5934\u90e8\u300c\u9009\u9879\u300d\u5b57\u6bb5\u91cc\u52a0\u4e00\u4e2a SACK<\/code> \u7684\u4e1c\u897f\uff0c\u5b83\u53ef\u4ee5\u5c06\u7f13\u5b58\u7684\u5730\u56fe\u53d1\u9001\u7ed9\u53d1\u9001\u65b9<\/strong>\uff0c\u8fd9\u6837\u53d1\u9001\u65b9\u5c31\u53ef\u4ee5\u77e5\u9053\u54ea\u4e9b\u6570\u636e\u6536\u5230\u4e86\uff0c\u54ea\u4e9b\u6570\u636e\u6ca1\u6536\u5230\uff0c\u77e5\u9053\u4e86\u8fd9\u4e9b\u4fe1\u606f\uff0c\u5c31\u53ef\u4ee5\u53ea\u91cd\u4f20\u4e22\u5931\u7684\u6570\u636e<\/strong>\u3002<\/p>\n\n\n\n

            \u5982\u4e0b\u56fe\uff0c\u53d1\u9001\u65b9\u6536\u5230\u4e86\u4e09\u6b21\u540c\u6837\u7684 ACK \u786e\u8ba4\u62a5\u6587\uff0c\u4e8e\u662f\u5c31\u4f1a\u89e6\u53d1\u5feb\u901f\u91cd\u53d1\u673a\u5236\uff0c\u901a\u8fc7 SACK<\/code> \u4fe1\u606f\u53d1\u73b0\u53ea\u6709 200~299<\/code> \u8fd9\u6bb5\u6570\u636e\u4e22\u5931\uff0c\u5219\u91cd\u53d1\u65f6\uff0c\u5c31\u53ea\u9009\u62e9\u4e86\u8fd9\u4e2a TCP \u6bb5\u8fdb\u884c\u91cd\u590d\u3002<\/p>\n\n\n\n

            \"\"
            \u9009\u62e9\u6027\u786e\u8ba4<\/figcaption><\/figure>\n\n\n\n

            <\/p>\n\n\n\n

            \u5982\u679c\u8981\u652f\u6301 SACK<\/code>\uff0c\u5fc5\u987b\u53cc\u65b9\u90fd\u8981\u652f\u6301\u3002\u5728 Linux \u4e0b\uff0c\u53ef\u4ee5\u901a\u8fc7 net.ipv4.tcp_sack<\/code> \u53c2\u6570\u6253\u5f00\u8fd9\u4e2a\u529f\u80fd\uff08Linux 2.4 \u540e\u9ed8\u8ba4\u6253\u5f00\uff09\u3002<\/p>\n\n\n\n

            <\/p>\n\n\n\n

            Duplicate SACK<\/h2>\n\n\n\n

            Duplicate SACK \u53c8\u79f0 D-SACK<\/code>\uff0c\u5176\u4e3b\u8981\u4f7f\u7528\u4e86 SACK \u6765\u544a\u8bc9\u300c\u53d1\u9001\u65b9\u300d\u6709\u54ea\u4e9b\u6570\u636e\u88ab\u91cd\u590d\u63a5\u6536\u4e86\u3002<\/strong><\/p>\n\n\n\n

            \u4e0b\u9762\u4e3e\u4f8b\u4e24\u4e2a\u6817\u5b50\uff0c\u6765\u8bf4\u660e D-SACK<\/code> \u7684\u4f5c\u7528\u3002<\/p>\n\n\n\n

            \u6817\u5b50\u4e00\u53f7\uff1aACK \u4e22\u5305<\/em><\/p>\n\n\n\n

            \"\"
            ACK \u4e22\u5305<\/figcaption><\/figure>\n\n\n\n

            <\/p>\n\n\n\n

            • \u300c\u63a5\u6536\u65b9\u300d\u53d1\u7ed9\u300c\u53d1\u9001\u65b9\u300d\u7684\u4e24\u4e2a ACK \u786e\u8ba4\u5e94\u7b54\u90fd\u4e22\u5931\u4e86\uff0c\u6240\u4ee5\u53d1\u9001\u65b9\u8d85\u65f6\u540e\uff0c\u91cd\u4f20\u7b2c\u4e00\u4e2a\u6570\u636e\u5305\uff083000 ~ 3499\uff09<\/li>
            • \u4e8e\u662f\u300c\u63a5\u6536\u65b9\u300d\u53d1\u73b0\u6570\u636e\u662f\u91cd\u590d\u6536\u5230\u7684\uff0c\u4e8e\u662f\u56de\u4e86\u4e00\u4e2a SACK = 3000~3500<\/strong>\uff0c\u544a\u8bc9\u300c\u53d1\u9001\u65b9\u300d 3000~3500 \u7684\u6570\u636e\u65e9\u5df2\u88ab\u63a5\u6536\u4e86\uff0c\u56e0\u4e3a ACK \u90fd\u5230\u4e86 4000 \u4e86\uff0c\u5df2\u7ecf\u610f\u5473\u7740 4000 \u4e4b\u524d\u7684\u6240\u6709\u6570\u636e\u90fd\u5df2\u6536\u5230\uff0c\u6240\u4ee5\u8fd9\u4e2a SACK \u5c31\u4ee3\u8868\u7740 D-SACK<\/code>\u3002<\/li>
            • \u8fd9\u6837\u300c\u53d1\u9001\u65b9\u300d\u5c31\u77e5\u9053\u4e86\uff0c\u6570\u636e\u6ca1\u6709\u4e22\uff0c\u662f\u300c\u63a5\u6536\u65b9\u300d\u7684 ACK \u786e\u8ba4\u62a5\u6587\u4e22\u4e86\u3002<\/li><\/ul>\n\n\n\n

              \u6817\u5b50\u4e8c\u53f7\uff1a\u7f51\u7edc\u5ef6\u65f6<\/em><\/p>\n\n\n\n

              \"\"
              \u7f51\u7edc\u5ef6\u65f6<\/figcaption><\/figure>\n\n\n\n

              <\/p>\n\n\n\n

              • \u6570\u636e\u5305\uff081000~1499\uff09 \u88ab\u7f51\u7edc\u5ef6\u8fdf\u4e86\uff0c\u5bfc\u81f4\u300c\u53d1\u9001\u65b9\u300d\u6ca1\u6709\u6536\u5230 Ack 1500 \u7684\u786e\u8ba4\u62a5\u6587\u3002<\/li>
              • \u800c\u540e\u9762\u62a5\u6587\u5230\u8fbe\u7684\u4e09\u4e2a\u76f8\u540c\u7684 ACK \u786e\u8ba4\u62a5\u6587\uff0c\u5c31\u89e6\u53d1\u4e86\u5feb\u901f\u91cd\u4f20\u673a\u5236\uff0c\u4f46\u662f\u5728\u91cd\u4f20\u540e\uff0c\u88ab\u5ef6\u8fdf\u7684\u6570\u636e\u5305\uff081000~1499\uff09\u53c8\u5230\u4e86\u300c\u63a5\u6536\u65b9\u300d\uff1b<\/li>
              • \u6240\u4ee5\u300c\u63a5\u6536\u65b9\u300d\u56de\u4e86\u4e00\u4e2a SACK=1000~1500\uff0c\u56e0\u4e3a ACK \u5df2\u7ecf\u5230\u4e86 3000\uff0c\u6240\u4ee5\u8fd9\u4e2a SACK \u662f D-SACK\uff0c\u8868\u793a\u6536\u5230\u4e86\u91cd\u590d\u7684\u5305\u3002<\/strong><\/li>
              • \u8fd9\u6837\u53d1\u9001\u65b9\u5c31\u77e5\u9053\u5feb\u901f\u91cd\u4f20\u89e6\u53d1\u7684\u539f\u56e0\u4e0d\u662f\u53d1\u51fa\u53bb\u7684\u5305\u4e22\u4e86\uff0c\u4e5f\u4e0d\u662f\u56e0\u4e3a\u56de\u5e94\u7684 ACK \u5305\u4e22\u4e86\uff0c\u800c\u662f\u56e0\u4e3a\u7f51\u7edc\u5ef6\u8fdf\u4e86\u3002<\/li><\/ul>\n\n\n\n

                \u53ef\u89c1\uff0cD-SACK<\/code> \u6709\u8fd9\u4e48\u51e0\u4e2a\u597d\u5904\uff1a<\/p>\n\n\n\n

                1. \u53ef\u4ee5\u8ba9\u300c\u53d1\u9001\u65b9\u300d\u77e5\u9053\uff0c\u662f\u53d1\u51fa\u53bb\u7684\u5305\u4e22\u4e86\uff0c\u8fd8\u662f\u63a5\u6536\u65b9\u56de\u5e94\u7684 ACK \u5305\u4e22\u4e86;<\/li>
                2. \u53ef\u4ee5\u77e5\u9053\u662f\u4e0d\u662f\u300c\u53d1\u9001\u65b9\u300d\u7684\u6570\u636e\u5305\u88ab\u7f51\u7edc\u5ef6\u8fdf\u4e86;<\/li>
                3. \u53ef\u4ee5\u77e5\u9053\u7f51\u7edc\u4e2d\u662f\u4e0d\u662f\u628a\u300c\u53d1\u9001\u65b9\u300d\u7684\u6570\u636e\u5305\u7ed9\u590d\u5236\u4e86;<\/li><\/ol>\n\n\n\n

                  \u5728 Linux \u4e0b\u53ef\u4ee5\u901a\u8fc7 net.ipv4.tcp_dsack<\/code> \u53c2\u6570\u5f00\u542f\/\u5173\u95ed\u8fd9\u4e2a\u529f\u80fd\uff08Linux 2.4 \u540e\u9ed8\u8ba4\u6253\u5f00\uff09\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"

                  \u8f6c\u8f7d\u4e8e\uff1ahttps:\/\/www.cnblogs.com\/xiaolincoding\/p\/12732052.ht […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[4],"tags":[],"_links":{"self":[{"href":"http:\/\/blog.kijk.top\/index.php?rest_route=\/wp\/v2\/posts\/240"}],"collection":[{"href":"http:\/\/blog.kijk.top\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/blog.kijk.top\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/blog.kijk.top\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/blog.kijk.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=240"}],"version-history":[{"count":6,"href":"http:\/\/blog.kijk.top\/index.php?rest_route=\/wp\/v2\/posts\/240\/revisions"}],"predecessor-version":[{"id":266,"href":"http:\/\/blog.kijk.top\/index.php?rest_route=\/wp\/v2\/posts\/240\/revisions\/266"}],"wp:attachment":[{"href":"http:\/\/blog.kijk.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=240"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/blog.kijk.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=240"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/blog.kijk.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=240"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}