{"id":296,"date":"2011-12-15T14:33:56","date_gmt":"2011-12-15T06:33:56","guid":{"rendered":"http:\/\/ykyi.net\/?p=296"},"modified":"2011-12-15T14:33:56","modified_gmt":"2011-12-15T06:33:56","slug":"unix%e7%bd%91%e7%bb%9c%e7%bc%96%e7%a8%8b-%e7%ac%ac%e4%b8%83%e7%ab%a0%e7%ac%94%e8%ae%b0","status":"publish","type":"post","link":"https:\/\/ykyi.net\/?p=296","title":{"rendered":"Unix\u7f51\u7edc\u7f16\u7a0b.\u7b2c\u4e03\u7ae0\u7b14\u8bb0"},"content":{"rendered":"
1. \u6709\u4e00\u4e2a Generic Socket Option<\/span>\uff1a<\/span>SO_BROADCAST <\/span>\u7528\u6765\u5f00\u542f\u662f\u5426\u5145\u8bb8\u5e7f\u64ad\u3002<\/span>2. \u4ec5\u6709TCP<\/span>\u652f\u6301<\/span>SO_DEBUG<\/span>\u3002<\/span>Kernel<\/span>\u628a\u8be6\u7ec6\u7684\u53d1\u9001\u5305\u7684\u63a5\u6536\u5305\u4fe1\u606f\u5b58\u5728\u4e00\u4e2a\u73af\u8def<\/span>buffer<\/span>\u91cc\u3002\u53ef\u4ee5\u7528<\/span>trpt<\/span>\u67e5\u770b\u5b83\u3002<\/span>3. SO_ERROR\u5957\u63a5\u5b57\u9009\u9879\u53ea\u80fd\u88ab\u53d6\u5f97\uff0c\u4e0d\u80fd\u88ab\u8bbe\u7f6e\u3002\u5982\u679c\u8fdb\u7a0b\u963b\u585e\u5728<\/span>select<\/span>\u8c03\u7528\u91cc\uff0c\u4e0d\u8bba\u662f\u8bfb\u8fd8\u662f\u5199\uff0c<\/span>select<\/span>\u90fd\u4f1a\u8fd4\u56de<\/span>conditions set<\/span>\u3002\u5982\u679c\u8fdb\u7a0b\u4f7f\u7528<\/span>signal-driven I\/O<\/span>\uff0c\u5219<\/span>SIGIO<\/span>\u4fe1\u53f7\u4f1a\u88ab\u53d1\u5230\u8fd9\u4e2a\u8fdb\u7a0b\u6216\u8005\u5b83\u6240\u5728\u7684\u8fdb\u7a0b\u7ec4\u3002\u8fdb\u7a0b\u7528<\/span>getsockopt<\/span>\u5f97\u5230<\/span>so_error<\/span>\u540e\uff0c<\/span>so_error<\/span>\u5c31\u4f1a\u88ab\u91cd\u7f6e\u4e3a<\/span>0.<\/span>\u5982\u679c<\/span>so_error<\/span>\u4e0d\u4e3a<\/span>0<\/span>\uff0c\u6b64\u65f6\u8c03\u7528 <\/span>read <\/span>\u6216\u8005 <\/span>write <\/span>\u5c31\u4f1a\u7acb\u5373\u8fd4\u56de<\/span>-1<\/span>\uff0c<\/span>errno<\/span>\u88ab\u7f6e\u4e3a<\/span>so_error<\/span>\u7684\u503c\u3002<\/span><\/p>\n

 <\/p>\n

 <\/p>\n

4. SO_KEEPALIVE\u5728\u4e00\u4e2a<\/span>tcp<\/span>\u8fde\u63a5\u6ca1\u6709\u4efb\u4f55\u6536\u53d1\u8fbe\u4e24\u4e2a\u5c0f\u65f6\u65f6\u4f1a\u53d1\u4e00\u4e2a<\/span>prob<\/span>\u7ed9\u5bf9\u65b9\u3002\u4e24\u4e2a\u949f\u5594\u3002\u597d\u957f\u7684\u65f6\u95f4\u554a\uff01\uff01\uff01<\/span>Richard Stevens<\/span>\u8ba4\u4e3a<\/span>SO_KEEPALIVE<\/span>\u5e94\u8be5\u6539\u53eb <\/span>make-dead<\/span>\u3002\u5927\u591a<\/span>Unix<\/span>\u7684<\/span>kernel<\/span>\u628a\u8fd9\u4e2a\u4e24\u5c0f\u65f6\u65f6\u957f\u5b58\u4e3a\u4e00\u4e2a\u7cfb\u7edf\u7ea7\u7684\u53d8\u91cf\u3002\u8fd9\u610f\u5473\u7740\u5982\u679c\u4f60\u7528\u67d0\u79cd\u65b9\u6cd5\u6539\u53d8\u4e86\u8fd9\u4e2a\u65f6\u957f\uff0c\u4f1a\u5f71\u54cd\u8fd9\u4e2a\u64cd\u4f5c\u7cfb\u7edf\u7684\u6240\u6709<\/span>socket.Richard Stevens<\/span>\u8ba4\u4e3a\u60f3\u628a\u8fd9\u4e2a\u65f6\u957f\u6539\u77ed\u7684\u60f3\u6cd5\u662f\u9519\u8bef\u7406\u89e3\u4e86\u8fd9\u4e2a\u9009\u9879\u7684\u610f\u4e49\u3002<\/span><\/p>\n

5. SO_LINGER\u4ec5\u4ec5\u9002\u7528\u4e8e\u9762\u5411\u8fde\u63a5\u7684<\/span>socket<\/span>\uff0c\u6bd4\u5982<\/span>TCP<\/span>\u548c<\/span>SCTP<\/span>\uff0c\u56e0\u6b64\u4e0d\u9002\u7528<\/span>UDP<\/span>\u3002<\/span><\/p>\n

Struct linger{<\/p>\n

int l_onofff;<\/p>\n

int l_linger;<\/p>\n

};<\/p>\n

L_onoff\u4e3a\u96f6\u662f\uff0c<\/span>close<\/span>\u7684<\/span>behavior<\/span>\u5c31\u662f\u9ed8\u8ba4\u60c5\u51b5\uff1a<\/span>close<\/span>\u7acb\u5373\u8fd4\u56de\uff0c<\/span>kernel<\/span>\u7ee7\u7eed\u53d1\u9001\u7f13\u51b2\u533a\u5185\u672a\u53d1\u9001\u7684\u6570\u636e\u3002\u5f53<\/span>l_onoff<\/span>\u4e0d\u4e3a\u96f6\uff0c\u800c<\/span>l_linger<\/span>\u4e3a<\/span>0<\/span>\uff0c<\/span>TCP<\/span>\u534f\u8bae\u5219\u4f1a\u7acb\u5373\u7ec8\u6b62\u8fde\u63a5\uff0c\u53d1\u9001<\/span>RST<\/span>\u7ed9<\/span>peer<\/span>\u7aef\uff0c\u8fd9\u6837\u505a\u907f\u514d\u4e86<\/span>TCP<\/span>\u7684<\/span>TIME_WAIT<\/span>\u72b6\u6001\uff0c\u8fd9\u6837\u7684\u574f\u5904\u662f<\/span>: leaves open the possibility of another incarnation of this connection being created within 2MSL seconds and having old duplicate segments from the just-terminated connection being incorrectly delivered to the new incarnation.<\/span>\u5bf9\u4e8e<\/span>SCTP, <\/span>\u4e5f\u4f1a\u53d1\u9001\u4e00\u4e2a<\/span>ABORT chunk<\/span>\u7ed9<\/span>peer.<\/span>\u7b2c\u4e09\u79cd\u60c5\u51b5\uff1a\u5982\u679c<\/span>l_onoff<\/span>\u4e3a\u771f\uff0c<\/span>l_linger<\/span>\u4e0d\u4e3a<\/span>0.<\/span>\u5219<\/span>close<\/span>\u4e0d\u4f1a\u7acb\u5373\u8fd4\u56de\uff0c\u4f1a\u6700\u591a\u7b49\u5f85\u6307\u5b9a\u7684\u65f6\u957f\uff0c\u5728\u8fd9\u6bb5\u65f6\u95f4\u91cc<\/span>kernel<\/span>\u53d1\u9001\u7f13\u51b2\u533a\u5185\u7684\u6570\u636e\u7ed9<\/span>peer<\/span>\u3002\u5982\u679c\u5728\u8fd9\u6bb5\u65f6\u95f4\u5185\u53d1\u9001\u5b8c\u5219<\/span>close<\/span>\u8fd4\u56de<\/span>0.<\/span>\u5982\u679c\u6ca1\u6709\u53d1\u9001\u5b8c\u6bd5\uff0c<\/span>close<\/span>\u5c31\u4f1a\u8fd4\u56de<\/span>EWOULDBLOCK<\/span>\uff0c<\/span>send buffer<\/span>\u91cc\u7684\u6570\u636e\u4f1a\u88ab\u4e22\u5f03\u3002<\/span><\/p>\n

6. MSL: maximum segment lifetime.<\/p>\n

7. \u56e0\u6b64close<\/span>\u9ed8\u8ba4\u60c5\u51b5\u4e0b\u7acb\u5373\u8fd4\u56de\uff0c\u5373\u4f7f\u7528<\/span>SO_LINGER<\/span>\u8bbe\u7f6e\u7b49\u5f85\u65f6\u95f4\u4e5f\u5728\u7406\u8bba\u4e0a\u5b58\u5728<\/span>close<\/span>\u5148\u4e8e\u53d1\u9001\u7f13\u51b2\u533a\u7684\u6570\u636e\u88ab<\/span>peer<\/span>\u7aef<\/span>acknowleded<\/span>\u7684\u60c5\u51b5\u3002\u56e0\u6b64\u4e00\u4e2a\u66f4\u597d\u7684\u89e3\u51b3\u65b9\u6848\u662f\u7528<\/span>shutdown<\/span>\u7cfb\u7edf\u8c03\u7528<\/span>with a second argument of SHUT_WR<\/span>\u3002\u5728\u8c03\u7528<\/span>shutdown<\/span>\u540e\uff0c\u7528<\/span>read<\/span>\u8c03\u7528\u76f4\u5230<\/span>read<\/span>\u8fd4\u56de<\/span>0<\/span>\uff0c\u5373\u6536\u5230<\/span>peer<\/span>\u7aef\u7684<\/span>FIN<\/span>\u3002<\/span><\/p>\n

8. UDP\u6ca1\u6709<\/span>congestion control<\/span>\uff0c\u5982\u679c\u53d1\u5f97\u592a\u5feb\uff0c\u4e0d\u4ec5\u4ec5<\/span>peer<\/span>\u7aef\u6765\u4e0d\u53ca\u6536\u3002<\/span>A fast sender can overwhelm its own network interface, causing datagrams to be discarded by the sender itself.<\/span><\/p>\n

9. \u56e0\u4e3atcp<\/span>\u5728\u4e09\u6b21\u63e1\u624b\u9636\u6bb5\u7684<\/span>SYN segment<\/span>\u91cc\u4ea4\u6362\u7a97\u53e3\u5927\u5c0f<\/span>(windows scale)<\/span>\u3002\u6240\u4ee5<\/span>tcp<\/span>\u7684\u63a5\u6536\u7f13\u51b2\u5927\u5c0f\u5fc5\u987b\u5728<\/span>shank hands<\/span>\u4e4b\u524d\u5c31\u8bbe\u7f6e\u597d\u3002<\/span>Connected socket<\/span>\u4ece<\/span>listening socket<\/span>\u7ee7\u627f\u8fd9\u4e2a\u9009\u9879\u3002<\/span><\/p>\n

10. TCP\u7684\u5957\u63a5\u5b57\u7f13\u51b2\u533a\u5927\u5c0f\u81f3\u5c11\u9700\u8981\u662f<\/span>4<\/span>\u500d<\/span>MSS<\/span>\u7684\u5927\u5c0f\u3002<\/span>\u8fd9\u91cc\u6307\u7684\u5957\u63a5\u5b57\u7f13\u51b2\uff0c\u5982\u679c\u662f\u9488\u5bf9\u5355\u5411\u7684\u4f20\u8f93\uff0c\u6bd4\u5982\u5355\u5411\u4f20\u4e00\u4e2a\u6587\u4ef6\uff0c\u6307\u7684\u662f\u53d1\u9001\u65b9\u7684\u53d1\u9001\u7f13\u51b2\u548c\u63a5\u6536\u65b9\u7684\u63a5\u6536\u7f13\u51b2\u3002\u5982\u679c\u662f\u53cc\u5411\u7684\u4f20\u8f93\uff0c\u5219\u6307\u7684\u662f\u53cc\u65b9\u7684\u63a5\u6536\u548c\u53d1\u9001\u7f13\u51b2\u3002\u4e3a\u4ec0\u4e48tcp<\/span>\u5957\u63a5\u5b57\u7684\u7f13\u51b2\u533a\u9700\u8981\u81f3\u5c11   \u662f<\/span>4<\/span>\u500d<\/span>MSS<\/span>\u7684\u5927\u5c0f\u5462\uff1f<\/span>\u8fd9\u662f\u56e0\u4e3atcp<\/span>\u7684\u5feb\u6062\u590d<\/span>(fast recovery)<\/span>\u7b97\u6cd5\u3002\u5feb\u6062\u590d\u7b97\u6cd5\u5b9a\u4e49\uff1a\u5982\u679c\u63a5\u6536\u7aef\u8fde\u7eed\u6536\u5230\u4e09\u4e2a\u540c\u6837\u7684<\/span>ACK<\/span>\uff0c\u5c31\u8ba4\u4e3a\u6709<\/span>packet<\/span>\u4e22\u5931\u4e86\u3002\u800c\u63a5\u6536\u7aef\u5728<\/span>segment<\/span>\u4e22\u5931\u540e\uff0c\u6bcf\u6536\u5230\u65b0\u7684<\/span>segment<\/span>\u5c31\u4e0d\u505c\u5730\u91cd\u53d1\u4e00\u4e2a\u91cd\u590d\u7684<\/span>ack<\/span>\u7ed9<\/span>sender<\/span>\u3002\u5982\u679c\u7a97\u53e3\u5927\u5c0f\u5c0f\u4e8e<\/span>4<\/span>\u4e2a<\/span>segments,<\/span>\u5c31\u4e0d\u4f1a\u6709\u4e09\u4e2a\u91cd\u590d\u7684<\/span>ACK,<\/span>\u6240\u4ee5\u5feb\u6062\u590d\u7b97\u6cd5\u5c31\u6ca1\u529e\u6cd5\u5de5\u4f5c\u4e86\u3002<\/span><\/p>\n

11. What is bandwidth-delay product.<\/p>\n

A: The capacity of the pipe is called the bandwidth-delay product and we calculate this by multiplying the bandwidth(in bits\/sec) times the RTT(in seconds), converting the result from bits to bytes. \u5373\u7f51\u901f\u4e58\u4e0a<\/span>RTT.<\/span><\/p>\n

12. UDP\u6ca1\u6709<\/span>send buffer<\/span>\uff0c\u4f46\u6709\u4e00\u4e2a<\/span>send buffer size.<\/span>\u53ea\u8981<\/span>socket<\/span>\u7684<\/span>buffer size<\/span>\u5927\u4e8e<\/span>LO_WATER<\/span>\uff0c\u5c31\u6c38\u8fdc\u662f\u53ef\u5199\u7684\u3002<\/span><\/p>\n

13. SO_REUSEADDR\u6709\u56db\u79cd\u7528\u9014\u3002\u597d\u96be\u5199\u3002\u89c1<\/span>Unix Network Programming Section 7.5 <\/span>\u5f71\u5370\u7248\u7b2c<\/span>211<\/span>\u9875\u5566\u3002<\/span><\/p>\n

14. It's Ok for the MSS to be different in each direction.<\/p>\n

15. Nagle\u7b97\u6cd5\u662f\u4e3a\u4e86\u51cf\u5c11<\/span>small package<\/span>\u7684\u6570\u91cf.<\/span>The algorithm states that if a given connection has outstanding data, then no small packets will be sent on the connection in response to a user write operation until the existing data is acknowledged. Small package <\/span>\u6307\u7684\u662f\u4efb\u4f55\u6bd4<\/span>MSS<\/span>\u5c0f\u7684<\/span>package.<\/span><\/p>\n

16. Delayed ACK algorithm: This algorithm causes TCP to not send an ACK immediately when it receives data; instead, TCP will wait some small amount of time (typically 50-200ms)and only then send the ACK.<\/p>\n

17. SCTP\u6709\u4e00\u4e2a<\/span>SCTP_AUTOCLOSE<\/span>\u5957\u63a5\u5b57\u9009\u9879\u3002<\/span>This option allows us to fetch or set the autoclose time for an SCTP endpoint. The autoclose time is the number of seconds an SCTP association will remain open when idle.<\/span>\u5373<\/span>SCTP association<\/span>\u80fd\u591f\u4fdd\u6301\u7a7a\u95f2\u72b6\u6001\u7684\u6700\u957f\u65f6\u95f4\u3002\u8d85\u65f6\u5c31\u4f1a\u88ab\u5173\u95ed\u3002<\/span><\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

1. \u6709\u4e00\u4e2a Generic Socket Option\uff1aSO_BROADCAST \u7528\u6765\u5f00\u542f\u662f\u5426\u5145\u8bb8\u5e7f\u64ad\u30022. \u4ec5\u6709TCP\u652f\u6301SO_DEBUG\u3002Kernel\u628a\u8be6\u7ec6\u7684\u53d1\u9001\u5305\u7684\u63a5\u6536\u5305\u4fe1\u606f\u5b58\u5728\u4e00\u4e2a\u73af\u8defbuffer\u91cc\u3002\u53ef\u4ee5\u7528trpt\u67e5\u770b\u5b83\u30023. SO_ERROR\u5957\u63a5\u5b57\u9009\u9879\u53ea\u80fd\u88ab\u53d6\u5f97\uff0c\u4e0d\u80fd\u88ab\u8bbe\u7f6e\u3002\u5982\u679c\u8fdb\u7a0b\u963b\u585e\u5728select\u8c03\u7528\u91cc\uff0c\u4e0d\u8bba\u662f\u8bfb\u8fd8\u662f\u5199\uff0cselect\u90fd\u4f1a\u8fd4\u56deconditions set\u3002\u5982\u679c\u8fdb\u7a0b\u4f7f\u7528signal-driven I\/O\uff0c\u5219SIGIO\u4fe1\u53f7\u4f1a\u88ab\u53d1\u5230\u8fd9\u4e2a\u8fdb\u7a0b\u6216\u8005\u5b83\u6240\u5728\u7684\u8fdb\u7a0b\u7ec4\u3002\u8fdb\u7a0b\u7528getsockopt\u5f97\u5230so_error\u540e\uff0cso_error\u5c31\u4f1a\u88ab\u91cd\u7f6e\u4e3a0.\u5982\u679cso_error\u4e0d\u4e3a0\uff0c\u6b64\u65f6\u8c03\u7528 read \u6216\u8005 write \u5c31\u4f1a\u7acb\u5373\u8fd4\u56de-1\uff0cerrno\u88ab\u7f6e\u4e3aso_error\u7684\u503c\u3002     4. SO_KEEPALIVE\u5728\u4e00\u4e2atcp\u8fde\u63a5\u6ca1\u6709\u4efb\u4f55\u6536\u53d1\u8fbe\u4e24\u4e2a\u5c0f\u65f6\u65f6\u4f1a\u53d1\u4e00\u4e2aprob\u7ed9\u5bf9\u65b9\u3002\u4e24\u4e2a\u949f\u5594\u3002\u597d\u957f\u7684\u65f6\u95f4\u554a\uff01\uff01\uff01Richard Stevens\u8ba4\u4e3aSO_KEEPALIVE\u5e94\u8be5\u6539\u53eb make-dead\u3002\u5927\u591aUnix\u7684kernel\u628a\u8fd9\u4e2a\u4e24\u5c0f\u65f6\u65f6\u957f\u5b58\u4e3a\u4e00\u4e2a\u7cfb\u7edf\u7ea7\u7684\u53d8\u91cf\u3002\u8fd9\u610f\u5473\u7740\u5982\u679c\u4f60\u7528\u67d0\u79cd\u65b9\u6cd5\u6539\u53d8\u4e86\u8fd9\u4e2a\u65f6\u957f\uff0c\u4f1a\u5f71\u54cd\u8fd9\u4e2a\u64cd\u4f5c\u7cfb\u7edf\u7684\u6240\u6709socket.Richard Stevens\u8ba4\u4e3a\u60f3\u628a\u8fd9\u4e2a\u65f6\u957f\u6539\u77ed\u7684\u60f3\u6cd5\u662f\u9519\u8bef\u7406\u89e3\u4e86\u8fd9\u4e2a\u9009\u9879\u7684\u610f\u4e49\u3002 5. SO_LINGER\u4ec5\u4ec5\u9002\u7528\u4e8e\u9762\u5411\u8fde\u63a5\u7684socket\uff0c\u6bd4\u5982TCP\u548cSCTP\uff0c\u56e0\u6b64\u4e0d\u9002\u7528UDP\u3002 Struct linger{ int l_onofff; int l_linger; }; L_onoff\u4e3a\u96f6\u662f\uff0cclose\u7684behavior\u5c31\u662f\u9ed8\u8ba4\u60c5\u51b5\uff1aclose\u7acb\u5373\u8fd4\u56de\uff0ckernel\u7ee7\u7eed\u53d1\u9001\u7f13\u51b2\u533a\u5185\u672a\u53d1\u9001\u7684\u6570\u636e\u3002\u5f53l_onoff\u4e0d\u4e3a\u96f6\uff0c\u800cl_linger\u4e3a0\uff0cTCP\u534f\u8bae\u5219\u4f1a\u7acb\u5373\u7ec8\u6b62\u8fde\u63a5\uff0c\u53d1\u9001RST\u7ed9peer\u7aef\uff0c\u8fd9\u6837\u505a\u907f\u514d\u4e86TCP\u7684TIME_WAIT\u72b6\u6001\uff0c\u8fd9\u6837\u7684\u574f\u5904\u662f: leaves open the possibility of another incarnation of this connection being created within 2MSL seconds and having old duplicate segments from the just-terminated connection being incorrectly delivered to the new incarnation.\u5bf9\u4e8eSCTP, \u4e5f\u4f1a\u53d1\u9001\u4e00\u4e2aABORT chunk\u7ed9peer.\u7b2c\u4e09\u79cd\u60c5\u51b5\uff1a\u5982\u679cl_onoff\u4e3a\u771f\uff0cl_linger\u4e0d\u4e3a0.\u5219close\u4e0d\u4f1a\u7acb\u5373\u8fd4\u56de\uff0c\u4f1a\u6700\u591a\u7b49\u5f85\u6307\u5b9a\u7684\u65f6\u957f\uff0c\u5728\u8fd9\u6bb5\u65f6\u95f4\u91cckernel\u53d1\u9001\u7f13\u51b2\u533a\u5185\u7684\u6570\u636e\u7ed9peer\u3002\u5982\u679c\u5728\u8fd9\u6bb5\u65f6\u95f4\u5185\u53d1\u9001\u5b8c\u5219close\u8fd4\u56de0.\u5982\u679c\u6ca1\u6709\u53d1\u9001\u5b8c\u6bd5\uff0cclose\u5c31\u4f1a\u8fd4\u56deEWOULDBLOCK\uff0csend buffer\u91cc\u7684\u6570\u636e\u4f1a\u88ab\u4e22\u5f03\u3002 6. MSL: maximum segment lifetime. 7. \u56e0\u6b64close\u9ed8\u8ba4\u60c5\u51b5\u4e0b\u7acb\u5373\u8fd4\u56de\uff0c\u5373\u4f7f\u7528SO_LINGER\u8bbe\u7f6e\u7b49\u5f85\u65f6\u95f4\u4e5f\u5728\u7406\u8bba\u4e0a\u5b58\u5728close\u5148\u4e8e\u53d1\u9001\u7f13\u51b2\u533a\u7684\u6570\u636e\u88abpeer\u7aefacknowleded\u7684\u60c5\u51b5\u3002\u56e0\u6b64\u4e00\u4e2a\u66f4\u597d\u7684\u89e3\u51b3\u65b9\u6848\u662f\u7528shutdown\u7cfb\u7edf\u8c03\u7528with a second argument of SHUT_WR\u3002\u5728\u8c03\u7528shutdown\u540e\uff0c\u7528read\u8c03\u7528\u76f4\u5230read\u8fd4\u56de0\uff0c\u5373\u6536\u5230peer\u7aef\u7684FIN\u3002 8. UDP\u6ca1\u6709congestion control\uff0c\u5982\u679c\u53d1\u5f97\u592a\u5feb\uff0c\u4e0d\u4ec5\u4ec5peer\u7aef\u6765\u4e0d\u53ca\u6536\u3002A fast sender can overwhelm its own network interface, causing datagrams to be discarded by the sender itself. 9. \u56e0\u4e3atcp\u5728\u4e09\u6b21\u63e1\u624b\u9636\u6bb5\u7684SYN segment\u91cc\u4ea4\u6362\u7a97\u53e3\u5927\u5c0f(windows scale)\u3002\u6240\u4ee5tcp\u7684\u63a5\u6536\u7f13\u51b2\u5927\u5c0f\u5fc5\u987b\u5728shank hands\u4e4b\u524d\u5c31\u8bbe\u7f6e\u597d\u3002Connected socket\u4ecelistening socket\u7ee7\u627f\u8fd9\u4e2a\u9009\u9879\u3002 10. TCP\u7684\u5957\u63a5\u5b57\u7f13\u51b2\u533a\u5927\u5c0f\u81f3\u5c11\u9700\u8981\u662f4\u500dMSS\u7684\u5927\u5c0f\u3002\u8fd9\u91cc\u6307\u7684\u5957\u63a5\u5b57\u7f13\u51b2\uff0c\u5982\u679c\u662f\u9488\u5bf9\u5355\u5411\u7684\u4f20\u8f93\uff0c\u6bd4\u5982\u5355\u5411\u4f20\u4e00\u4e2a\u6587\u4ef6\uff0c\u6307\u7684\u662f\u53d1\u9001\u65b9\u7684\u53d1\u9001\u7f13\u51b2\u548c\u63a5\u6536\u65b9\u7684\u63a5\u6536\u7f13\u51b2\u3002\u5982\u679c\u662f\u53cc\u5411\u7684\u4f20\u8f93\uff0c\u5219\u6307\u7684\u662f\u53cc\u65b9\u7684\u63a5\u6536\u548c\u53d1\u9001\u7f13\u51b2\u3002\u4e3a\u4ec0\u4e48tcp\u5957\u63a5\u5b57\u7684\u7f13\u51b2\u533a\u9700\u8981\u81f3\u5c11   \u662f4\u500dMSS\u7684\u5927\u5c0f\u5462\uff1f\u8fd9\u662f\u56e0\u4e3atcp\u7684\u5feb\u6062\u590d(fast recovery)\u7b97\u6cd5\u3002\u5feb\u6062\u590d\u7b97\u6cd5\u5b9a\u4e49\uff1a\u5982\u679c\u63a5\u6536\u7aef\u8fde\u7eed\u6536\u5230\u4e09\u4e2a\u540c\u6837\u7684ACK\uff0c\u5c31\u8ba4\u4e3a\u6709packet\u4e22\u5931\u4e86\u3002\u800c\u63a5\u6536\u7aef\u5728segment\u4e22\u5931\u540e\uff0c\u6bcf\u6536\u5230\u65b0\u7684segment\u5c31\u4e0d\u505c\u5730\u91cd\u53d1\u4e00\u4e2a\u91cd\u590d\u7684ack\u7ed9sender\u3002\u5982\u679c\u7a97\u53e3\u5927\u5c0f\u5c0f\u4e8e4\u4e2asegments,\u5c31\u4e0d\u4f1a\u6709\u4e09\u4e2a\u91cd\u590d\u7684ACK,\u6240\u4ee5\u5feb\u6062\u590d\u7b97\u6cd5\u5c31\u6ca1\u529e\u6cd5\u5de5\u4f5c\u4e86\u3002 11. What is bandwidth-delay product. A: The capacity of the pipe is called the bandwidth-delay product and we calculate this by multiplying the bandwidth(in bits\/sec) times the RTT(in seconds), converting the result from bits to bytes. \u5373\u7f51\u901f\u4e58\u4e0aRTT. 12. UDP\u6ca1\u6709send buffer\uff0c\u4f46\u6709\u4e00\u4e2asend buffer size.\u53ea\u8981socket\u7684buffer size\u5927\u4e8eLO_WATER\uff0c\u5c31\u6c38\u8fdc\u662f\u53ef\u5199\u7684\u3002 13. SO_REUSEADDR\u6709\u56db\u79cd\u7528\u9014\u3002\u597d\u96be\u5199\u3002\u89c1Unix Network Programming Section 7.5 \u5f71\u5370\u7248\u7b2c211\u9875\u5566\u3002 14. It's Ok for the MSS to be different in each direction. 15. Nagle\u7b97\u6cd5\u662f\u4e3a\u4e86\u51cf\u5c11small package\u7684\u6570\u91cf.The algorithm states that if a given connection has outstanding data, then no small packets will be sent on the connection in response to a user write operation until the existing data is acknowledged. Small package \u6307\u7684\u662f\u4efb\u4f55\u6bd4MSS\u5c0f\u7684package. 16. Delayed ACK algorithm: This algorithm causes TCP to not send an ACK immediately when it receives data; instead, TCP will wait some small amount of time (typically 50-200ms)and only then send the ACK. 17. SCTP\u6709\u4e00\u4e2aSCTP_AUTOCLOSE\u5957\u63a5\u5b57\u9009\u9879\u3002This option allows us to fetch or set the autoclose time for an SCTP endpoint. The autoclose time is the number of seconds an SCTP association will remain open when idle.\u5373SCTP association\u80fd\u591f\u4fdd\u6301\u7a7a\u95f2\u72b6\u6001\u7684\u6700\u957f\u65f6\u95f4\u3002\u8d85\u65f6\u5c31\u4f1a\u88ab\u5173\u95ed\u3002<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4,6,7],"tags":[82,116],"class_list":["post-296","post","type-post","status-publish","format-standard","hentry","category-network","category-tech_articles","category-unix_linux","tag-unix-socket","tag-116"],"_links":{"self":[{"href":"https:\/\/ykyi.net\/index.php?rest_route=\/wp\/v2\/posts\/296","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ykyi.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ykyi.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ykyi.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ykyi.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=296"}],"version-history":[{"count":0,"href":"https:\/\/ykyi.net\/index.php?rest_route=\/wp\/v2\/posts\/296\/revisions"}],"wp:attachment":[{"href":"https:\/\/ykyi.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=296"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ykyi.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=296"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ykyi.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=296"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}