{"id":826,"date":"2019-10-08T12:16:27","date_gmt":"2019-10-08T04:16:27","guid":{"rendered":"http:\/\/149.129.74.185\/?p=826"},"modified":"2019-10-08T12:16:27","modified_gmt":"2019-10-08T04:16:27","slug":"%e8%ae%a1%e7%ae%97%e6%9c%ba%e7%bd%91%e7%bb%9cweek-4-note","status":"publish","type":"post","link":"http:\/\/www.magicmipamipa.com\/?p=826","title":{"rendered":"[\u8ba1\u7b97\u673a\u7f51\u7edc]Week 4 Note"},"content":{"rendered":"

\u6570\u636e\u94fe\u8def\u5c42 Datalink<\/h2>\n

3.1\u6570\u636e\u94fe\u8def\u5c42\u7684\u8bbe\u8ba1\u95ee\u9898 Design Issues<\/p>\n

\u6570\u636e\u94fe\u8def\u5c42\u7684\u529f\u80fd\uff1a<\/p>\n

    \n
  1. \u5411\u7f51\u7edc\u5c42\u5b9a\u4e49\u4e00\u4e2a\u597d\u7684\u670d\u52a1\u63a5\u53e3<\/li>\n
  2. \u5904\u7406\u4f20\u8f93\u9519\u8bef<\/li>\n
  3. \u8c03\u8282\u6570\u636e\u6d41\uff0c\u786e\u4fdd\u6162\u901f\u7684\u63a5\u6536\u65b9\u4e0d\u4f1a\u88ab\u5feb\u901f\u7684\u53d1\u9001\u65b9\u6df9\u6ca1\u3002<\/li>\n<\/ol>\n

    \u6570\u636e\u94fe\u8def\u5c42\u3010\u5e27\u5934\u3011+\u3010\u6709\u6548\u8377\u8f7d\uff08\u7528\u4e8e\u5b58\u653e\u6570\u636e\u5305\uff09\u3011+\u3010\u5e27\u5c3e\u3011\uff0c\u5c06\u6570\u636e\u5305\u5c01\u88c5\u8d77\u6765\u3002<\/p>\n

    1.\u63d0\u4f9b\u7ed9\u7f51\u7edc\u5c42\u7684\u670d\u52a1 Service Interface<\/p>\n

    \/\/\u8d1f\u8d23\u53d1\u73b0\u7269\u7406\u5c42\u4f20\u8f93\u7684\u9519\u8bef \uff1f\u5355\u4e00\u4fe1\u53f7\u65e0\u6cd5\u7ea0\u6b63\uff0c\u5bf9\u4fe1\u53f7\u6d41\u8fdb\u884c\u68c0\u6d4b<\/span><\/p>\n

      \n
    1. \u65e0\u786e\u8ba4\u7684\u65e0\u8fde\u63a5<\/li>\n
    2. \u6709\u786e\u8ba4\u7684\u65e0\u8fde\u63a5<\/li>\n
    3. \u6709\u786e\u8ba4\u7684\u6709\u8fde\u63a5<\/li>\n<\/ol>\n

      2.\u6210\u5e27Framing (PDU)<\/p>\n

      1.Character Count\u5b57\u8282\u8ba1\u6570\u6cd5\uff08\u4e0d\u597d\uff09<\/p>\n

      \u5f88\u5bb9\u6613\u4ea7\u751f\u8fde\u7eed\u9519\u8bef<\/p>\n

      2.Starting and ending character, with character stuffing\u5b57\u8282\u586b\u5145\u7684\u6807\u5fd7\u5b57\u8282\u6cd5<\/p>\n

      3.Starting and ending flags, with bit stuffing\u6bd4\u7279\u586b\u5145\u7684\u6807\u5fd7\u6bd4\u7279\u6cd5<\/p>\n

      4.Physical layer coding violations\u7269\u7406\u5c42\u7f16\u7801\u8fdd\u7981\u6cd5<\/p>\n

      3.\u5dee\u9519\u63a7\u5236 Error Control<\/p>\n

      \u8ba1\u65f6\u5668\u3001\u5e8f\u53f7<\/p>\n

       <\/p>\n

      4.\u6d41\u91cf\u63a7\u5236 Flow Control<\/p>\n

      \u673a\u5668\u6d41\u91cf\u5dee\u8fc7\u5927\u4f1a\u5bfc\u81f4\u6570\u636e\u4e22\u5931\u3002<\/p>\n

      \u57fa\u4e8e\u53cd\u9988\u7684\u6d41\u91cf\u63a7\u5236<\/p>\n

      \u57fa\u4e8e\u901f\u7387\u7684\u6d41\u91cf\u63a7\u5236<\/p><\/blockquote>\n

       <\/p>\n

      3.2 \u5dee\u9519\u68c0\u6d4b\u548c\u7ea0\u6b63<\/p>\n

      1.\u5355\u4e2a\u9519\u8bef Single Error \/\/\u968f\u673a\u5206\u5e03\u7684\u9519\u8bef<\/p>\n

      2.\u7a81\u53d1\u6027\u9519\u8bef Burst Error \/\/\u96c6\u4e2d\u65f6\u95f4\u6bb5\uff0c\u96c6\u4e2d\u540c\u4e00\u533a\u57df<\/p>\n

      3.\u6d77\u660e\u8ddd\u79bb Hamming Distance<\/p>\n

      \u68c0\u6d4bd\u6bd4\u7279\u7684\u9519\u8bef\uff0c\u9700\u8981d+1\u7684\u8ddd\u79bb\uff08\u6b63\u786e\u7684\u7f16\u7801\u548c\u9519\u8bef\u7f16\u7801\u7684\u8ddd\u79bb\uff09<\/p>\n

      \u5947\u5076\u6821\u9a8c\u4f4d\u53ef\u4ee5\u68c0\u6d4b\u51fa1\u6bd4\u7279\u7684\u9519\u8bef\uff0c\u4f46\u662f\u4e0d\u77e5\u9053\u662f\u54ea\u4e00\u6bd4\u7279\u7684\u9519\u8bef<\/p><\/blockquote>\n

      \u4fee\u6b63d\u6bd4\u7279\u7684\u9519\u8bef\uff0c\u9700\u89812d+1\u7684\u8ddd\u79bb<\/p>\n

      4.Parity Check<\/p>\n

      5.Hamming Code<\/p>\n

      6.CRC \u5faa\u73af\u5197\u4f59\u6821\u9a8c<\/p>\n

      \u6821\u9a8c\u7b97\u6cd5\u7684\u9664\u6570\uff1a<\/p>\n

      CRC-12 = X12 + X11 + X3 + X2 + X1 + 1<\/p>\n

      CRC-16 = X16 + X15 + X2 + 1<\/p>\n

      CRC-CCITT = X16 + X12 + X5 + 1<\/p>\n

       <\/p>\n

      3.\u57fa\u672c\u6570\u636e\u94fe\u8def\u5c42\u534f\u8bae<\/p>\n

      1.Stop-and-Wait\u505c\u7b49\u5f0f\u534f\u8baeARQ<\/p>\n

      \u5b58\u5728\u9519\u8bef\u7684\u60c5\u51b5\uff08\u8bf7\u6c42\u91cd\u53d1request\uff09\uff1a<\/p>\n

      Data-><\/p>\n

      <-NAK<\/p>\n

      Data(Retransmission)-><\/p>\n

      <-ACK<\/p>\n

      Data next-><\/p><\/blockquote>\n

      \u6216<\/p>\n

      \u6570\u636e\u4e22\u5931\u7684\u60c5\u51b5\uff08\u81ea\u52a8\u91cd\u53d1auto\uff09\uff1a\/\/\u5f00\u59cb\u6807\u8bb0\u88ab\u7834\u574f\u4e86<\/p>\n

      Data-><\/p>\n

      —-Time Out—-(\u63a5\u6536\u65b9\u65e0\u54cd\u5e94\/\u5728\u5b9a\u65f6\u5668\u8303\u56f4\u540e\u91cd\u53d1)<\/p>\n

      Data(Retransmission)-><\/p>\n

      <-ACK<\/p>\n

      Data next-><\/p><\/blockquote>\n

      \u6216<\/p>\n

      ACK\u4e22\u5931\u7684\u60c5\u51b5\uff08\u81ea\u52a8\u91cd\u53d1\uff09<\/p>\n

      Data-><\/p>\n

      <-ACK<\/p>\n

      —-Time Out—-<\/p>\n

      Data(Retransmission)->\/\/\u53d1\u9001\u7684\u6570\u636e\u5fc5\u987b\u6709\u5e8f\u53f7\u6bd4\u8f83<\/p>\n

      —-Discard this Data—-\/\/\u91cd\u53d1\u7684\u6570\u636e\u4e0d\u4ea4\u7ed9\u7f51\u7edc\u5c42<\/p>\n

      <-ACK<\/p>\n

      Data next-><\/p><\/blockquote>\n

      Utlization of Stop-and-wait \u5229\u7528\u7387<\/p>\n

      Tframe<\/sub> = FramSize \/ Bitrate<\/p>\n

      Tprop<\/sub> = Distance \/ Speed of Signal<\/p>\n

      Utlization = Tframe<\/sub> \/ \uff082Tprop<\/sub> + Tframe<\/sub>\uff09<\/p>\n

      2.\u6ed1\u52a8\u7a97\u53e3\u534f\u8bae Sliding Window Protocols<\/p>\n

      Utlization = N*Tframe<\/sub> \/ \uff082Tprop<\/sub> + Tframe<\/sub>\uff09<\/p>\n

        \n
      • Sender Window \u63d0\u524d\u53d1\u9001\u591a\u5c11\u4e2a\u7a97\u53e3<\/li>\n
      • Piggybacking \u5c06\u786e\u8ba4\u5e27\u6253\u5305\/\u5c01\u88c5\u5230\u6570\u636e\u4e2d<\/li>\n<\/ul>\n

        \u53d8\u5f0f\uff1a<\/p>\n

        Go-back-N ARQ(Data Error)\/\/\u53ea\u6539A\uff0c\u4e0d\u6539B<\/p>\n

        Data 1-> ACK 1<\/p>\n

        Data 2-> Discard 2<\/p>\n

        Data 3-> Discard 3<\/p>\n

        <- ACK 1<\/p>\n

        Data 4 -> Discard 4<\/p>\n

        Resend Data 2 -> ACK 2<\/p>\n

        Resend Data 3 -> ACK 3<\/p>\n

        <- ACK 2<\/p>\n

        <- ACK 3<\/p><\/blockquote>\n

        Receive Window Size = 1<\/p>\n

        Send Window Size <= MAX_SEQ – 1 (0,…,N)<\/p>\n

        \u6b63\u786e\u7684\u60c5\u51b5\uff1a<\/p>\n

        Data 01234567 -><\/p>\n

        <- ACK 7<\/p>\n

        Data 0(new) ->Send to Network layer<\/p><\/blockquote>\n

        \u9519\u8bef\u7684\u60c5\u51b5<\/p>\n

        Data 01234567 -><\/p>\n

        <- ACK 7 ( lost )<\/p>\n

        —-Time Out—-<\/p>\n

        Data 0(old) -> ????<\/p><\/blockquote>\n

        \u53d8\u5f0f2\uff1a<\/p>\n

        Selective Repeat ARQ<\/p>\n

          \n
        • Send Window Size <= (Max_SEQ+1)\/2<\/li>\n
        • Receive Window Size = Send Window Size<\/li>\n
        • Receive Buffer Number = Window Size<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"

          \u6570\u636e\u94fe\u8def\u5c42 Datalink 3.1\u6570\u636e\u94fe\u8def\u5c42\u7684\u8bbe\u8ba1\u95ee\u9898 Design Issues \u6570\u636e\u94fe\u8def\u5c42\u7684\u529f […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[19,16],"tags":[],"_links":{"self":[{"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=\/wp\/v2\/posts\/826"}],"collection":[{"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=826"}],"version-history":[{"count":1,"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=\/wp\/v2\/posts\/826\/revisions"}],"predecessor-version":[{"id":829,"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=\/wp\/v2\/posts\/826\/revisions\/829"}],"wp:attachment":[{"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=826"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=826"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=826"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}