2005-11-08 15:18\u4f5c\u8005\uff1a\u51fa\u5904\uff1a\u8d23\u4efb\u7f16\u8f91\uff1a\u7f57\u53ef\u9f99 <\/p>\n
\u3000\u3000[\u80cc\u666f\u77e5\u8bc6] <\/p>\n
\u3000\u3000MTU: Maxitum Transmission Unit \u6700\u5927\u4f20\u8f93\u5355\u5143 <\/p>\n
\u3000\u3000MSS: Maxitum Segment Size \u6700\u5927\u5206\u6bb5\u5927\u5c0f(\u5076\u662f\u76f4\u8bd1\uff0c\u7ffb\u8bd1\u7684\u4e0d\u597d\uff0c\u4e0d\u8981\u6253\u4ffaPP) <\/p>\n
\u3000\u3000PPPoE: PPP Over Ethernet(\u5728\u4ee5\u592a\u7f51\u4e0a\u627f\u8f7dPPP\u534f\u8bae) <\/p>\n
\u3000\u3000[\u5206\u6790\u8fc7\u7a0b] <\/p>\n
\u3000\u3000\u5148\u8bf4\u8bf4\u8fd9MTU\u6700\u5927\u4f20\u8f93\u5355\u5143\uff0c\u8fd9\u4e2a\u6700\u5927\u4f20\u8f93\u5355\u5143\u5b9e\u9645\u4e0a\u548c\u94fe\u8def\u5c42\u534f\u8bae\u6709\u7740\u5bc6\u5207\u7684\u5173\u7cfb\uff0c\u8ba9\u6211\u4eec\u5148\u4ed4\u7ec6\u56de\u5fc6\u4e00\u4e0bEthernetII\u5e27\u7684\u7ed3\u6784DMAC+SMAC+Type+Data+CRC <\/p>\n
\u3000\u3000\u7531\u4e8e\u4ee5\u592a\u7f51\u4f20\u8f93\u7535\u6c14\u65b9\u9762\u7684\u9650\u5236\uff0c\u6bcf\u4e2a\u4ee5\u592a\u7f51\u5e27\u90fd\u6709\u6700\u5c0f\u7684\u5927\u5c0f64bytes\u6700\u5927\u4e0d\u80fd\u8d85\u8fc71518bytes\uff0c\u5bf9\u4e8e\u5c0f\u4e8e\u6216\u8005\u5927\u4e8e\u8fd9\u4e2a\u9650\u5236\u7684\u4ee5\u592a\u7f51\u5e27\u6211\u4eec\u90fd\u53ef\u4ee5\u89c6\u4e4b\u4e3a\u9519\u8bef\u7684\u6570\u636e\u5e27\uff0c\u4e00\u822c\u7684\u4ee5\u592a\u7f51\u8f6c\u53d1\u8bbe\u5907\u4f1a\u4e22\u5f03\u8fd9\u4e9b\u6570\u636e\u5e27\u3002 <\/p>\n
\u3000\u3000(\u6ce8:\u5c0f\u4e8e64Bytes\u7684\u6570\u636e\u5e27\u4e00\u822c\u662f\u7531\u4e8e\u4ee5\u592a\u7f51\u51b2\u7a81\u4ea7\u751f\u7684\u201c\u788e\u7247\u201d\u6216\u8005\u7ebf\u8def\u5e72\u6270\u6216\u8005\u574f\u7684\u4ee5\u592a\u7f51\u63a5\u53e3\u4ea7\u751f\u7684\uff0c\u5bf9\u4e8e\u5927\u4e8e1518Bytes\u7684\u6570\u636e\u5e27\u6211\u4eec\u4e00\u822c\u628a\u5b83\u53eb\u505aGiant\u5e27\uff0c\u8fd9\u79cd\u4e00\u822c\u662f\u7531\u4e8e\u7ebf\u8def\u5e72\u6270\u6216\u8005\u574f\u7684\u4ee5\u592a\u7f51\u53e3\u4ea7\u751f) <\/p>\n
\u3000\u3000\u7531\u4e8e\u4ee5\u592a\u7f51EthernetII\u6700\u5927\u7684\u6570\u636e\u5e27\u662f1518Bytes\u8fd9\u6837\uff0c\u5228\u53bb\u4ee5\u592a\u7f51\u5e27\u7684\u5e27\u5934(DMAC\u76ee\u7684MAC\u5730\u574048bit=6Bytes+SMAC\u6e90MAC\u5730\u574048bit=6Bytes+Type\u57df2bytes)14Bytes\u548c\u5e27\u5c3eCRC\u6821\u9a8c\u90e8\u52064Bytes(\u8fd9\u4e2a\u90e8\u95e8\u6709\u65f6\u5019\u5927\u5bb6\u4e5f\u628a\u5b83\u53eb\u505aFCS)\uff0c\u90a3\u4e48\u5269\u4e0b\u627f\u8f7d\u4e0a\u5c42\u534f\u8bae\u7684\u5730\u65b9\u4e5f\u5c31\u662fData\u57df\u6700\u5927\u5c31\u53ea\u80fd\u67091500Bytes\u8fd9\u4e2a\u503c\u6211\u4eec\u5c31\u628a\u5b83\u79f0\u4e4b\u4e3aMTU\u3002\u8fd9\u4e2a\u5c31\u662f\u7f51\u7edc\u5c42\u534f\u8bae\u975e\u5e38\u5173\u5fc3\u7684\u5730\u65b9\uff0c\u56e0\u4e3a\u7f51\u7edc\u5c42\u534f\u8bae\u6bd4\u5982IP\u534f\u8bae\u4f1a\u6839\u636e\u8fd9\u4e2a\u503c\u6765\u51b3\u5b9a\u662f\u5426\u628a\u4e0a\u5c42\u4f20\u4e0b\u6765\u7684\u6570\u636e\u8fdb\u884c\u5206\u7247\u3002\u5c31\u597d\u6bd4\u4e00\u4e2a\u76d2\u5b50\u6ca1\u6cd5\u88c5\u4e0b\u4e00\u5927\u5757\u9762\u5305\uff0c\u6211\u4eec\u9700\u8981\u628a\u9762\u5305\u5207\u6210\u7247\uff0c\u88c5\u5728\u591a\u4e2a\u76d2\u5b50\u91cc\u9762\u4e00\u6837\u7684\u9053\u7406\u3002 <\/p>\n
\u3000\u3000\u5f53\u4e24\u53f0\u8fdc\u7a0bPC\u4e92\u8054\u7684\u65f6\u5019\uff0c\u5b83\u4eec\u7684\u6570\u636e\u9700\u8981\u7a7f\u8fc7\u5f88\u591a\u7684\u8def\u7531\u5668\u548c\u5404\u79cd\u5404\u6837\u7684\u7f51\u7edc\u5a92\u4ecb\u624d\u80fd\u5230\u8fbe\u5bf9\u7aef\uff0c\u7f51\u7edc\u4e2d\u4e0d\u540c\u5a92\u4ecb\u7684MTU\u5404\u4e0d\u76f8\u540c\uff0c\u5c31\u597d\u6bd4\u4e00\u957f\u6bb5\u7684\u6c34\u7ba1\uff0c\u7531\u4e0d\u540c\u7c97\u7ec6\u7684\u6c34\u7ba1\u7ec4\u6210(MTU\u4e0d\u540c )\u901a\u8fc7\u8fd9\u6bb5\u6c34\u7ba1\u6700\u5927\u6c34\u91cf\u5c31\u8981\u7531\u4e2d\u95f4\u6700\u7ec6\u7684\u6c34\u7ba1\u51b3\u5b9a\u3002 <\/p>\n
\u3000\u3000\u5bf9\u4e8e\u7f51\u7edc\u5c42\u7684\u4e0a\u5c42\u534f\u8bae\u800c\u8a00(\u6211\u4eec\u4ee5TCP\/IP\u534f\u8bae\u65cf\u4e3a\u4f8b)\u5b83\u4eec\u5bf9\u6c34\u7ba1\u7c97\u7ec6\u4e0d\u5728\u610f\u5b83\u4eec\u8ba4\u4e3a\u8fd9\u4e2a\u662f\u7f51\u7edc\u5c42\u7684\u4e8b\u60c5\u3002\u7f51\u7edc\u5c42IP\u534f\u8bae\u4f1a\u68c0\u67e5\u6bcf\u4e2a\u4ece\u4e0a\u5c42\u534f\u8bae\u4e0b\u6765\u7684\u6570\u636e\u5305\u7684\u5927\u5c0f\uff0c\u5e76\u6839\u636e\u672c\u673aMTU\u7684\u5927\u5c0f\u51b3\u5b9a\u662f\u5426\u4f5c\u201c\u5206\u7247\u201d\u5904\u7406\u3002\u5206\u7247\u6700\u5927\u7684\u574f\u5904\u5c31\u662f <\/p>\n
\u3000\u3000\u964d\u4f4e\u4e86\u4f20\u8f93\u6027\u80fd\uff0c\u672c\u6765\u4e00\u6b21\u53ef\u4ee5\u641e\u5b9a\u7684\u4e8b\u60c5\uff0c\u5206\u6210\u591a\u6b21\u641e\u5b9a\uff0c\u6240\u4ee5\u5728\u7f51\u7edc\u5c42\u66f4\u9ad8\u4e00\u5c42(\u5c31\u662f\u4f20\u8f93\u5c42)\u7684\u5b9e\u73b0\u4e2d\u5f80\u5f80\u4f1a\u5bf9\u6b64\u52a0\u4ee5\u6ce8\u610f!\u6709\u4e9b\u9ad8\u5c42\u56e0\u4e3a\u67d0\u4e9b\u539f\u56e0\u5c31\u4f1a\u8981\u6c42\u6211\u8fd9\u4e2a\u9762\u5305\u4e0d\u80fd\u5207\u7247\uff0c\u6211\u8981\u5b8c\u6574\u5730\u9762\u5305\uff0c\u6240\u4ee5\u4f1a\u5728IP\u6570\u636e\u5305\u5305\u5934\u91cc\u9762\u52a0\u4e0a\u4e00 <\/p>\n
\u3000\u3000\u4e2a\u6807\u7b7e:DF(Donot Fragment)\u3002\u8fd9\u6837\u5f53\u8fd9\u4e2aIP\u6570\u636e\u5305\u5728\u4e00\u5927\u6bb5\u7f51\u7edc(\u6c34\u7ba1\u91cc\u9762)\u4f20\u8f93\u7684\u65f6\u5019\uff0c\u5982\u679c\u9047\u5230MTU\u5c0f\u4e8eIP\u6570\u636e\u5305\u7684\u60c5\u51b5\uff0c\u8f6c\u53d1\u8bbe\u5907\u5c31\u4f1a\u6839\u636e\u8981\u6c42\u4e22\u5f03\u8fd9\u4e2a\u6570\u636e\u5305\u3002\u7136\u540e\u8fd4\u56de\u4e00\u4e2a\u9519\u8bef\u4fe1\u606f\u7ed9\u53d1\u9001\u8005\u3002\u8fd9\u6837\u5f80\u5f80\u4f1a\u9020\u6210\u67d0\u4e9b\u901a\u8baf\u4e0a\u7684\u95ee\u9898\uff0c\u4e0d\u8fc7\u5e78\u8fd0\u7684\u662f\u5927\u90e8\u5206\u7f51\u7edc\u94fe\u8def\u90fd\u662fMTU1500\u6216\u8005\u5927\u4e8e1500\u3002 <\/p>\n
\u3000\u3000\u5bf9\u4e8eUDP\u534f\u8bae\u800c\u8a00\uff0c\u8fd9\u4e2a\u534f\u8bae\u672c\u8eab\u662f\u65e0\u8fde\u63a5\u7684\u534f\u8bae\uff0c\u5bf9\u6570\u636e\u5305\u7684\u5230\u8fbe\u987a\u5e8f\u4ee5\u53ca\u662f\u5426\u6b63\u786e\u5230\u8fbe\u4e0d\u751a\u5173\u5fc3\uff0c\u6240\u4ee5\u4e00\u822cUDP\u5e94\u7528\u5bf9\u5206\u7247\u6ca1\u6709\u7279\u6b8a\u8981\u6c42\u3002 <\/p>\n
\u3000\u3000\u5bf9\u4e8eTCP\u534f\u8bae\u800c\u8a00\u5c31\u4e0d\u4e00\u6837\u4e86\uff0c\u8fd9\u4e2a\u534f\u8bae\u662f\u9762\u5411\u8fde\u63a5\u7684\u534f\u8bae\uff0c\u5bf9\u4e8eTCP\u534f\u8bae\u800c\u8a00\u5b83\u975e\u5e38\u5728\u610f\u6570\u636e\u5305\u7684\u5230\u8fbe\u987a\u5e8f\u4ee5\u53ca\u662f\u5426\u4f20\u8f93\u4e2d\u6709\u9519\u8bef\u53d1\u751f\u3002\u6240\u4ee5\u6709\u4e9bTCP\u5e94\u7528\u5bf9\u5206\u7247\u6709\u8981\u6c42---\u4e0d\u80fd\u5206\u7247(DF)\u3002 <\/p>\n
\u3000\u3000\u82b1\u5f00\u4e24\u6735\uff0c\u5404\u8868\u4e00\u679d\uff0c\u8bf4\u5b8cMTU\u7684\u6545\u4e8b\u6211\u4eec\u8be5\u8bb2\u8bb2\u4eca\u5929\u7684\u7b2c\u4e8c\u4e2a\u732a\u811a---PPPoE\u6240\u8c13PPPoE\u5c31\u662f\u5728\u4ee5\u592a\u7f51\u4e0a\u9762\u8dd1PPP\u534f\u8bae\uff0c\u6709\u4eba\u5947\u602a\u4e86\uff0cPPP\u534f\u8bae\u548cEthernet\u4e0d\u90fd\u662f\u94fe\u8def\u5c42\u534f\u8bae\u5417?\u600e\u4e48\u4e00\u4e2a\u94fe\u8def\u5c42\u8dd1\u5230\u53e6\u5916\u4e00\u4e2a\u94fe\u8def\u5c42\u4e0a\u9762\u53bb\u4e86\uff0c\u96be\u9053\u5347\u7ea7\u6210\u7f51\u7edc\u5c42\u534f\u8bae\u4e86\u4e0d\u6210\u3002\u5176\u5b9e\u8fd9\u662f\u4e2a\u8bef\u533a:\u5c31\u662f\u67d0\u5c42\u534f\u8bae\u53ea\u80fd\u627f\u8f7d\u66f4\u4e0a\u4e00\u5c42\u534f\u8bae\u3002 <\/p>\n
\u3000\u3000\u4e3a\u4ec0\u4e48\u4f1a\u4ea7\u751f\u8fd9\u79cd\u5947\u602a\u7684\u9700\u6c42\u5462?\u8fd9\u662f\u56e0\u4e3a\u968f\u7740\u5bbd\u5e26\u63a5\u5165(\u8fd9\u79cd\u5bbd\u5e26\u63a5\u5165\u4e00\u822c\u4e3aCable Modem\u6216\u8005xDSL\u6216\u8005\u4ee5\u592a\u7f51\u7684\u63a5\u5165)\u7531\u4e8e\u4ee5\u592a\u7f51\u7f3a\u4e4f\u8ba4\u8bc1\u8ba1\u8d39\u673a\u5236\u800c\u4f20\u7edf\u8fd0\u8425\u5546\u662f\u901a\u8fc7PPP\u534f\u8bae\u6765\u5bf9\u62e8\u53f7\u7b49\u63a5\u5165\u670d\u52a1\u8fdb\u884c\u8ba4\u8bc1\u8ba1\u8d39\u7684\uff0c\u6240\u4ee5\u5c31\u51fa\u4e86\u8fd9\u4e48\u4e00\u4e2a\u602a\u80ce:PPPoE\u3002(\u6709\u5173PPPoE\u7684\u8be6\u7ec6\u4ecb\u7ecd\u53c2\u89c1V\u5927\u4ee5\u53ca\u672c\u7ad9\u5176\u4ed6\u6210\u5458\u7684\u4e00\u4e9b\u4ecb\u7ecd\u6587\u7ae0\uff0c\u6211\u5c31\u4e0d\u5570\u91cc\u5570\u5506\u7684\u4e86) <\/p>\n
\u3000\u3000PPPoE\u5e26\u6765\u4e86\u597d\u5904\uff0c\u4e5f\u5e26\u6765\u4e86\u4e00\u4e9b\u574f\u5904\uff0c\u6bd4\u5982:\u4e8c\u6b21\u5c01\u88c5\u8017\u8d39\u8d44\u6e90\uff0c\u964d\u4f4e\u4e86\u4f20\u8f93\u6548\u80fd\u7b49\u7b49\uff0c\u8fd9\u4e9b\u574f\u5904\u4ffa\u4e5f\u4e0d\u591a\u8bf4\u4e86\uff0c\u6700\u5927\u7684\u574f\u5904\u5c31\u662fPPPoE\u5bfc\u81f4MTU\u53d8\u5c0f\u4e86\u4ee5\u592a\u7f51\u7684MTU\u662f1500\uff0c\u518d\u51cf\u53bbPPP\u7684\u5305\u5934\u5305\u5c3e\u7684\u5f00\u9500(8Bytes)\uff0c\u5c31\u53d8\u62101492\u3002 <\/p>\n
\u3000\u3000\u5982\u679c\u4e24\u53f0\u4e3b\u673a\u4e4b\u95f4\u7684\u67d0\u6bb5\u7f51\u7edc\u4f7f\u7528\u4e86PPPoE\u90a3\u4e48\u5c31\u4f1a\u5bfc\u81f4\u67d0\u4e9b\u4e0d\u80fd\u5206\u7247\u7684\u5e94\u7528\u65e0\u6cd5\u901a\u8baf\u3002 <\/p>\n
\u3000\u3000\u8fd9\u4e2a\u65f6\u5019\u5c31\u9700\u8981\u6211\u4eec\u8c03\u6574\u4e00\u4e0b\u4e3b\u673a\u7684MTU\uff0c\u901a\u8fc7\u964d\u4f4e\u4e3b\u673a\u7684MTU\uff0c\u8fd9\u6837\u6211\u4eec\u5c31\u80fd\u591f\u987a\u5229\u5730\u8fdb\u884c\u901a\u8baf\u4e86\u3002 <\/p>\n
\u3000\u3000\u5f53\u7136\u5bf9\u4e8eTCP\u5e94\u7528\u800c\u8a00\u8fd8\u6709\u53e6\u5916\u7684\u89e3\u51b3\u65b9\u6848\u3002 <\/p>\n
\u3000\u3000\u9a6c\u4e0a\u8bf7\u51fa\u4eca\u5929\u7b2c\u4e09\u4f4d\u732a\u811a:MSS\u3002 <\/p>\n
\u3000\u3000MSS\u6700\u5927\u4f20\u8f93\u5927\u5c0f\u7684\u7f29\u5199\uff0c\u662fTCP\u534f\u8bae\u91cc\u9762\u7684\u4e00\u4e2a\u6982\u5ff5\u3002 <\/p>\n
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\u3000\u3000\u4ecb\u7ecd\u5b8c\u8fd9\u4e09\u4f4d\u732a\u811as <\/p>\n
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