\u4e00\u822c\u800c\u8a00\uff0c\u9078\u8cfc\u5916\u570b\u7684\u865b\u64ec\u4e3b\u6a5f\uff0c\u53f0\u7063\u4eba\u7684\u9996\u9078\uff0c\u662f\u4ee5\u7f8e\u570b\u3001\u65e5\u672c\u70ba\u4e3b\u3002\u65e5\u672c\u7684\u8a71\uff0c\u7531\u65bc\u65e5\u6587\u9084\u662f\u6bd4\u8f03\u4e0d\u6bd4\u82f1\u6587\u666e\u904d\uff0c\u5927\u591a\u6578\u4eba\u9084\u662f\u5148\u8003\u616e\u7f8e\u570b\u3002<\/p>\n

\u6211\u770b\u4e86\u8a31\u591a\u7db2\u7ad9\u8a55\u6bd4\u7f8e\u570b\u7684\u865b\u64ec\u4e3b\u6a5f\uff0c\u8aaa\u4e86\u4e00\u5806\u670d\u52d9\u5e7e\u5206\uff1f\u6709\u6c92\u6709\u9001google adword\uff1f\u8eab\u70ba\u4e3b\u6a5f\u5546\u7684\u6211\uff0c\u6211\u89ba\u5f97\uff0c\u9019\u4e9b\u90fd\u4e0d\u662f\u5ba2\u6236\u8981\u7684\u3002\u5ba2\u6236\u8981\u7684\u6771\u897f\uff0c\u5c0d\u5ba2\u6236\u800c\u8a00\uff0c\u6700\u91cd\u8981\u7684\u6771\u897f\uff1a(1)\u7dda\u8def\u54c1\u8cea (2)\u50f9\u683c\u3002\u5176\u5b83\u7684\u4ec0\u9ebcgoogle adword\uff1f\u5ba2\u670d\u5982\u4f55\uff1f\u6a5f\u5668\u7684\u8edf\u4f53\u662f\u4e0d\u662f\u6700\u65b0\u7684\uff1f\u9019\u4e9b\u5e38\u5e38\u90fd\u4e0d\u662f\u5ba2\u6236\u6700\u5728\u610f\u7684\u4e8b\u3002<\/p>\n

\u8b93\u6211\u4f86\u89e3\u91cb\u4e00\u4e0b\uff0c\u4ec0\u9ebc\u662f\u7dda\u8def\u54c1\u8cea\u7684\u89c0\u5ff5\u5427\uff1a
\n\u6211\u5011\u7528ping\u9019\u500bcommand\u53bb\u9023\u9060\u7aef\u7684\u4e3b\u6a5f\u7684\u8a71\uff0c\u53ef\u4ee5\u5f97\u5230\u4e00\u500b\u6578\u5b57\uff0c\u53eb\u505aRTT\u3002\u9019\u500b\u6578\u5b57\uff0c\u5c0d\u65bc\u50b3\u8f38\u6709\u83ab\u5927\u7684\u5f71\u97ff\u3002\u600e\u9ebc\u8aaa\u5462\uff1f \u4ee5unethost\u7684\u7f8e\u570b\u897f\u5cb8\u4e3b\u6a5f\u4f86\u8b1b\uff0cRTT\u7d04\u662f150ms\u591a\u3002\u96d6\u7136\u4e3b\u6a5f\u672c\u8eab\u7684\u983b\u5bec\u662f100Mbps\uff0c\u4f46\u662f\uff0c\u5c0d\u65bc\u55ae\u4e00\u7684TCP\u9023\u7dda\uff0c\u8003\u616eTCP\u7684slow start effect & congestion control\u6548\u61c9\u4e4b\u5f8c\uff0c\u7406\u8ad6\u4e0a\u7684\u6700\u9ad8\u901f\u662f4.3Mbps \u6216\u662f500 kbyte\/sec\u3002\u7576\u7136\uff0c\u73fe\u4ee3\u7684\u700f\u89bd\u5668\u5df2\u7d93\u6709\u505a\u5e73\u884c\u7684\u9023\u7dda\uff0c\u4e00\u822c\u800c\u8a00\u6700\u591a\u662f\u5341\u689d\u3002\u4f46\u662f\u5e73\u884c\u7684\u9023\u7dda\u662f\u5c0d\u591a\u500b\u5c0f\u6a94\uff0c\u53ef\u4ee5\u52a0\u901f\uff0c\u5982\u679c\u662f\u4e00\u500b\u55ae\u4e00\u7684\u5927\u6a94\uff0c\u6216\u662f\u8aaa\u4e00\u500bPHP\u751f\u6210\u7684\u52d5\u614b\u9801\u9762\uff0c\u5c31\u4e00\u5b9a\u6703\u88ab\u9019\u500b\u901f\u5ea6\u6240\u9650\u5236\u3002<\/p>\n

\u9019\u500bRTT\u5982\u4f55\u5f71\u97ff\u55ae\u4e00\u9023\u7dda\u7684\u6700\u9ad8\u901f\uff0c\u5176\u5be6\u662f\u6709\u8a08\u7b97\u516c\u5f0f\u7684\u3002\u5927\u5bb6\u8981\u662f\u8a18\u4e0d\u4f4f\uff0c\u6982\u5ff5\u4e0a\u662fRTT\u6108\u5c0f\uff0c\u55ae\u4e00\u9023\u7dda\u7684\u6700\u9ad8\u901f\u9650\u6108\u5927\u3002\u8a73\u7d30\u63a8\u5c0e\u7684\u6d41\u7a0b\u662f\uff1aTCP\u5728\u50b3\u8f38\u7684\u6642\u5019\uff0c\u96fb\u8166\u6703\u5c0d\u6bcf\u4e00\u689dTCP\u9023\u7dda\u751f\u6210\u4e00\u500bSlilding window(\u6ed1\u52d5\u7a97\u6236)\u3002\u9019\u500bwindow\u7684\u5927\u5c0f\uff0c\u5fc5\u9808\u7b49\u65bcBDP = bandwidth delay product \u3002\u4e5f\u5c31\u662f\u8aaa\uff0c\u9019\u500b\u6ed1\u52d5\u7a97\u6236\u7684\u5927\u5c0f = \u983b\u5bec \u4e58\u4e0a RTT\u3002\u7531\u65bc\u4e00\u822c\u4f86\u8b1b\uff0c\u5927\u90e8\u5206\u7684\u4eba\u7528\u7684\u96fb\u8166OS\u662fwindows\uff0c\u5167\u5efa\u7684TCP\u6f14\u7b97\u6cd5\u4e5f\u4e0d\u662f\u6700\u65b0\u7684\uff0c\u6240\u4ee5Slilding window size\u662f\u56fa\u5b9a\u7684\uff1a64kbytes\u3002\u9019\u7a2e\u6642\u5019\uff0c\u983b\u5bec\u5c31\u53ef\u4ee5\u7531 ( Slilding window size\/ RTT)\u4f86\u7b97\u51fa\u3002<\/p>\n

\u800c\u4e0a\u982d\uff0c\u672c\u6587\u6240\u8b1b\u7684\u7406\u8ad6\u4e0a\u9650\u4e5f\u5c31\u662f\u9019\u6a23\u5b50\u7b97\u51fa\u4f86\u7684\u3002unethost\u7684\u4e3b\u6a5f\u6e2c\u901f\u8cc7\u6599\u5728\u9019\u908a<\/a>\u3002<\/p>\n

\u53c3\u8003\u8cc7\u6599\u53ef\u4ee5\u770b\u4e0b\u65b9\u7684\u82f1\u6587\u3002<\/p>\n

Sometimes, we are feeling\u00a0slow Internet connection, but don’t know how we can\u00a0measure\u00a0the speed and what is right speed, download speed,\u00a0TCP throughput<\/strong>, I\u00a0can expect.\u00a0Measuring\u00a0and calculating\u00a0TCP throughput<\/strong>\u00a0is not that hard. See below famous\u00a0TCP throughput<\/strong>\u00a0formula.<\/p>\n

RCV buffer size \/ RTT = Max TCP throughput = ? bps<\/strong>
\n** Buffer size is normally 65Kbps<\/span><\/strong><\/h3>\n

ex) (64Kbyte x 8bit) \/ 0.17 = 3011764 bps = 3Mbps, (RTT=170ms)<\/span><\/p>\n

To learn more about\u00a0Internet Speed Issue<\/strong><\/a>, please check our\u00a0article series<\/strong><\/a>\u00a0within www.ipBalance.com<\/p>\n

RCV Buffer size \/ TCP receive window size<\/strong><\/p>\n

– RCV buffer size is denoted as TCP receive window size. Window systems have 64Kbyte of window size as default (Window NT and Millennium have 8Kbytes of window size).\u00a0 The TCP\/IP standard allows for a receive window up to 65,535 bytes in size, which is the maximum value that can be specified in the 16-bit TCP window size field. Why 65Kbytes? Well, more accurate expression will be\u00a0 65,535 = (2^16)-1. To improve TCP throughput, speed, performance whatever you called, in high\u00a0speed connection\u00a0or high delay network, you can increase TCP window size(reference RFC 1323). However, if transport link is not stable, it might give you worse performance.\u00a0Packet\u00a0loss\u00a0or bottleneck in the network is the most likelyfactors\u00a0that are leading to the TCP throughput reductions.<\/span><\/p>\n

Optimal TCP window size<\/strong><\/p>\n

– Optimal RCV buffer size is considered to be\u00a02 x BDP, where BDP is the\u00a0Bandwidth<\/strong>\u00a0*\u00a0Delay Product<\/strong><\/span><\/p>\n

ex) RTT is 20 ms, and connection speed is 10 Mbps.
\n2 x (10Mbps\/8 * .020s) = 50Kbytes<\/span><\/p>\n

Well, default window size 65kbytes is not adequate for today’s network. In these days, most of network is 100Mbps or higher.<\/span><\/p>\n

Round Trip Time(RTT)<\/strong><\/p>\n

– If you\u00a0are not using\u00a0TCP window scaling option (RFC 1323), TCP window size will be used as 64Kbytes. If then, Round Trip Time(RTT) is the main\u00a0factor\u00a0to decide\u00a0TCP throughput<\/strong>\u00a0between locations.\u00a0<\/span><\/p>\n

RTT\u00a010 ms => TCP throughput =\u00a0<\/span>52428000 bps = 52Mbps
\nRTT\u00a020 ms => TCP throughput = 26214000 bps = 26Mbps
\n<\/span>RTT\u00a050 ms => TCP throughput = 10485600 bps = 10Mbps
\n<\/span>RTT\u00a0100 ms => TCP throughput = 5242800 bps = 5.2Mbps
\n<\/span>RTT\u00a0150 ms => TCP throughput = 3495200 bps = 4.3Mbps
\n<\/span>RTT\u00a0200 ms => TCP throughput = 2621400 bps = 2.5Mbps
\n<\/span>RTT\u00a0300 ms => TCP throughput = 1747600 bps = 1.7Mbps
\n<\/span>RTT\u00a0500 ms => TCP throughput = 1048560 bps = 1Mbps
\n<\/span>
\n** Used maximum TCP window size\u00a0 = 65Kbytes = 65535
\n<\/strong><\/p>\n

You can see the deficiency with the greater RTT.<\/span><\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

\u4e00\u822c\u800c\u8a00\uff0c\u9078\u8cfc\u5916\u570b\u7684\u865b\u64ec\u4e3b\u6a5f\uff0c\u53f0\u7063\u4eba\u7684\u9996\u9078\uff0c\u662f\u4ee5\u7f8e\u570b\u3001\u65e5\u672c\u70ba\u4e3b\u3002\u65e5\u672c\u7684\u8a71\uff0c\u7531\u65bc\u65e5\u6587\u9084\u662f\u6bd4\u8f03\u4e0d\u6bd4\u82f1\u6587\u666e\u904d\uff0c\u5927\u591a\u6578 … \u95b1\u8b80\u5168\u6587 \u5982\u4f55\u9078\u8cfc\u5916\u570b\u7684\u865b\u64ec\u4e3b\u6a5f\uff1f<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_mi_skip_tracking":false},"categories":[5],"tags":[28,29],"_links":{"self":[{"href":"https:\/\/blog.unethost.com\/wp-json\/wp\/v2\/posts\/121"}],"collection":[{"href":"https:\/\/blog.unethost.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.unethost.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.unethost.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.unethost.com\/wp-json\/wp\/v2\/comments?post=121"}],"version-history":[{"count":8,"href":"https:\/\/blog.unethost.com\/wp-json\/wp\/v2\/posts\/121\/revisions"}],"predecessor-version":[{"id":584,"href":"https:\/\/blog.unethost.com\/wp-json\/wp\/v2\/posts\/121\/revisions\/584"}],"wp:attachment":[{"href":"https:\/\/blog.unethost.com\/wp-json\/wp\/v2\/media?parent=121"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.unethost.com\/wp-json\/wp\/v2\/categories?post=121"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.unethost.com\/wp-json\/wp\/v2\/tags?post=121"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}