{"id":854,"date":"2018-03-20T17:12:40","date_gmt":"2018-03-21T02:12:40","guid":{"rendered":"\/blog\/?p=854"},"modified":"2023-09-21T09:37:36","modified_gmt":"2023-09-21T00:37:36","slug":"%eb%a6%ac%eb%88%85%ec%8a%a4-%ec%84%9c%eb%b2%84%ec%9d%98-tcp-%eb%84%a4%ed%8a%b8%ec%9b%8c%ed%81%ac-%ec%84%b1%eb%8a%a5%ec%9d%84-%ea%b2%b0%ec%a0%95%ec%a7%93%eb%8a%94-%ec%bb%a4%eb%84%90-%ed%8c%8c%eb%9d%bc","status":"publish","type":"post","link":"https:\/\/hasu0707.duckdns.org\/blog\/?p=854","title":{"rendered":"\ub9ac\ub205\uc2a4 \uc11c\ubc84\uc758 TCP \ub124\ud2b8\uc6cc\ud06c \uc131\ub2a5\uc744 \uacb0\uc815\uc9d3\ub294 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130 \uc774\uc57c\uae30"},"content":{"rendered":"\n

\ucd9c\ucc98 : http:\/\/meetup.toast.com\/posts\/53<\/span><\/p>\n\n<\/span>


\ubaa9\ucc28<\/span><\/span>
<\/p>\n\n<\/span>

  1. \ub4e4\uc5b4\uac00\uae30 \uc804\uc5d0<\/span><\/li>
  2. \uc900\ube44<\/span><\/li>
  3. TCP \ub300\uc5ed\ud3ed(bandwidth) \uad00\ub828 \ud30c\ub77c\ubbf8\ud130<\/span>
    3.1 BDP<\/span>
    3.2 TCP window scaling<\/span>
    3.3 TCP socket buffer size<\/span>
    3.4 congestion window size<\/span><\/li>
  4. \ub124\ud2b8\uc6cc\ud06c capacity \uad00\ub828 \ud30c\ub77c\ubbf8\ud130<\/span>
    4.1 maximum file count<\/span>
    4.2 backlogs<\/span>
    4.3 port range<\/span><\/li>
  5. TIME_WAIT socket<\/span>
    5.1 TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc774 \ubb34\uc5c7\uc77c\uae4c\uc694?<\/span>
    5.2 TIME_WAIT socket buckets<\/span>
    5.3 TIME_WAIT socket reuse (TW_REUSE)<\/span>
    5.4 TCP timestamp<\/span>
    5.5 TIME_WAIT socket recycling (TW_RECYCLE)<\/span>
    5.6 Socket linger option<\/span><\/li>
  6. \uacb0\ub860<\/span><\/li>
  7. \ub9fa\uc73c\uba70<\/span><\/li><\/ol>

    1. \ub4e4\uc5b4\uac00\uae30 \uc804\uc5d0<\/span><\/h2>

    \uba3c\uc800, \"TCP \ub124\ud2b8\uc6cc\ud06c \uc131\ub2a5\uc744 \uacb0\uc815\uc9d3\ub294...\" \uc774\ub77c\ub294 \uc218\uc2dd\uc5b4\ub294 \uc0ac\uc2e4 \uc870\uae08 \ub354 \uc790\uadf9\uc801\uc778 \uc81c\ubaa9\uc744 \ubf51\uc544\ub0b4\uae30 \uc704\ud55c \uacfc\uc695\uc785\ub2c8\ub2e4.<\/span><\/p>\n

    \ub124\ud2b8\uc6cc\ud06c \uc131\ub2a5\uc5d0 \uac00\uc7a5 \uc911\uc694\ud55c \uc694\uc18c\ub294 \uacb0\uad6d\uc5d4 \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc5d0 \uc788\ub2e4\ub294 \uc810\uc744 \uac15\uc870\ud558\uace0 \uc2f6\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>

    \ub2e4\ub9cc, \uc6cc\ud06c\ub85c\ub4dc \ud2b9\uc131\uc5d0 \ub530\ub77c \uae30\ubcf8 \uc124\uc815\ub41c TCP \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\uac00 \uc81c\uc57d\uc774 \ub418\uc5b4 \uc81c\uc131\ub2a5\uc744 \ubc1c\ud718\ud560 \uc218 \uc5c6\uc744\ub54c\ub3c4 \uc788\ub294\ub370\uc694.<\/span>
    \ubcf8\ubb38\uc5d0\uc11c\ub294 \uc774\ub7ec\ud55c \ub0b4\uc6a9\ub4e4\uc744 \ub2e4\ub8e8\uace0 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>

    \ub9e4\uc6b0 \ub9ce\uc740 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\uac00 \uc788\uaca0\uc9c0\ub9cc, \ubcf8\ubb38\uc5d0\uc11c\ub294 \ub124\ud2b8\uc6cc\ud06c \ub300\uc5ed\ud3ed(bandwidth)\uc5d0 \ub300\ud55c \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130, \ub124\ud2b8\uc6cc\ud06c \uc218\uc6a9\ub7c9(capacity)\uc5d0 \ub300\ud55c \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\ub97c \uc8fc\ub85c \ub2e4\ub8f9\ub2c8\ub2e4.<\/span><\/strong><\/p>\n\n<\/span>

    2. \uc900\ube44<\/span><\/h2>

    \ub9ac\ub205\uc2a4\ub294 <\/span>sysctl<\/span><\/code> \uba85\ub839\uc5b4\ub85c \uc190\uc27d\uac8c \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\ub97c \ub7f0\ud0c0\uc784 \uc911\uc5d0 \ubcc0\uacbd\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    \ub2e4\uc74c\uacfc \uac19\uc740 \uba85\ub839\uc5b4\ub97c \uc0ac\uc6a9\ud558\uba74 \ud604\uc7ac \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130 \uc124\uc815\uac12 \uc804\uccb4\ub97c \uc5f4\ub78c\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>

    $ sysctl -a\n<\/span><\/code><\/pre>
    \ubcf8 \ubb38\uc11c\uc5d0\uc11c\ub294 \ub124\ud2b8\uc6cc\ud06c, \ud2b9\ud788 TCP\uc758 capacity\uc640 bandwidth \ub4f1\uc744 \uc870\uc815(tuning)\ud560 \uc218 \uc788\ub294 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130 \uc911 \uc544\uc8fc \uc77c\ubd80 \ub9cc\uc744 \ub2e4\ub8f9\ub2c8\ub2e4.<\/span>
    \ub300\uac1c, TCP\uc640 \uad00\ub828\ub41c \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\ub294 net.core, net.ipv4, net.ipv6 \ub4f1\uc758 \uc811\ub450\uc0ac\ub97c \ubd99\uc774\uace0 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \ub610, \ub2e4\uc74c\uacfc \uac19\uc740 \uba85\ub839\uc5b4\ub85c \ud604\uc7ac \uc124\uc815\uac12\uc744 \ubcc0\uacbd\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    \uc608\ub97c \ub4e4\uc5b4 net.core.wmem_max \ub77c\ub294 \uc124\uc815\uac12\uc744 16777216\uc774\ub77c\uace0 \ubcc0\uacbd\ud558\ub824\uba74, \ub2e4\uc74c\uacfc \uac19\uc774 \uc785\ub825\ud558\uba74 \ub429\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ sysctl -w net.core.wmem_max=\"16777216\"\n<\/span><\/code><\/pre>
    \uc2dc\uc2a4\ud15c \ubd80\ud305\uc2dc \uc124\uc815\ub418\ub3c4\ub85d \ud558\ub824\uba74, \/etc\/sysctl.conf \ud30c\uc77c\uc5d0 \ud574\ub2f9 \uc124\uc815\uac12\uc744 \uae30\uc785\ud558\uba74 \ub429\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    3. TCP \ub300\uc5ed\ud3ed(bandwidth) \uad00\ub828 \ud30c\ub77c\ubbf8\ud130<\/span><\/h2>
    3.1 BDP<\/span><\/h3>
    TCP\uc758 \ub300\uc5ed\ud3ed\uc744 \uc774\ud574\ud558\ub824\uba74 \uba3c\uc800 <\/span>BDP(Bandwidth Delay Product)<\/span><\/code>\ub97c \uc774\ud574\ud560 \ud544\uc694\uac00 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uba3c\uc800, 100Mbps\uc758 \ub300\uc5ed\ud3ed\uc744 \uac00\uc9c0\ub294 \ub124\ud2b8\uc6cc\ud06c\uc5d0\uc11c \uc5b4\ub5a4 \ub450 host A, B \uc0ac\uc774 RTT(Round-trip time)\uac00 2\ucd08\uc778 \ub124\ud2b8\uc6cc\ud06c \uacbd\ub85c\uac00 \uc788\ub2e4\uace0 \uac00\uc815\ud569\uc2dc\ub2e4.<\/span>
    A\uc5d0\uc11c B\uae4c\uc9c0 \ub370\uc774\ud130\uac00 \uacc4\uc18d \uc804\uc1a1\ub418\uace0 \uc788\uc744\ub54c, A\uc5d0\uc11c \ucd9c\ubc1c\ud558\uc600\uc73c\ub098 \uc544\uc9c1 B\uc5d0 \ub3c4\ucc29\ud558\uc9c0 \uc54a\uc740 \ub370\uc774\ud130 \uc591(bits in flight)\uc740 \uc5bc\ub9c8\uc77c\uae4c\uc694?<\/span><\/p>\n\n<\/span>
    \uc544\ub798 \uadf8\ub9bc\uc744 \ubcf4\uba74 \uc870\uae08 \uc774\ud574\uac00 \uc26c\uc6b8 \uac83 \uac19\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \"img1.png\"<\/p>\n\n<\/span>
    <\/p>\n\n<\/span>
    \ub300\uc5ed\ud3ed\uc744 \ub108\ube44\ub85c, \uc9c0\uc5f0\uc2dc\uac04 RTT\ub97c \uae38\uc774\ub85c \uc0dd\uac01\ud558\uba74, \uc774 \ub458\uc758 \uacf1\uc774 \ub124\ud2b8\uc6cc\ud06c \uacbd\ub85c\uc0c1 \ub5a0\ub2e4\ub2c8\ub294 \ub370\uc774\ud130 \uc591\uc758 \ucd5c\ub300\uce58\ub97c \ub098\ud0c0\ub0bc \uac83\uc785\ub2c8\ub2e4.<\/span>
    \uc989, \ub300\uc5ed\ud3ed\uacfc \uc9c0\uc5f0\uc2dc\uac04\uc758 \uacf1, \ub2e4\uc2dc \ub9d0\ud574 BDP\ub294 \uc5b4\ub290 \ub124\ud2b8\uc6cc\ud06c \uacbd\ub85c\uc5d0 \uc804\ub2ec\uc911\uc778 \ub370\uc774\ud130(\ud328\ud0b7)\uc758 \uc591\uc744 \ub098\ud0c0\ub0c5\ub2c8\ub2e4.<\/span><\/strong><\/p>\n\n<\/span>
    \uc774 \uc608\uc81c\uc5d0\uc11c BDP\ub294 100Mb\/s * 2s = 200Mb \/ 8 = 25MB \uc815\ub3c4\uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \ub2e4\ub978 \uc608\ub97c \ub4e4\uc5b4\ubcf4\uc790\uba74, \uc5b4\ub290 \uc11c\ubc84\uc640 LTE \ub124\ud2b8\uc6cc\ud06c(40Mbps, 40ms RTT)\ub85c \uc5f0\uacb0\ub41c \ub2e8\ub9d0\uc774 \uc788\ub2e4\uace0 \uac00\uc815\ud569\uc2dc\ub2e4.<\/span>
    \uc774\ub54c BDP\ub294 (40<\/span>(10^6))bit\/s <\/span><\/em>(40<\/span>(10^-3))s =1600<\/span><\/em>(10^3)bit = 1.6Mb \/ 8 = 0.2MB \uc815\ub3c4\uc77c \uac83 \uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    BDP\uc758 \uc218\uc2dd\uc744 \uc774\uc6a9\ud558\uba74, \ub2e4\uc74c\uacfc \uac19\uc740 \uc2dd\uc744 \ub3c4\ucd9c\ud560 \uc218 \uc788\uc744 \uac83\uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    Bandwidth = BDP \/ RTT\n<\/span><\/code><\/pre>
    \uadf8\ub7f0\ub370 \ub9d0\uc785\ub2c8\ub2e4. \uc2e4\uc81c \uc778\ud130\ub137\uc5d0\uc11c BDP\ub294 \ub9e4\uc6b0 \ucda9\ubd84\ud788 \ud07d\ub2c8\ub2e4.<\/span>
    \uc6a9\ub7c9\uc774 \ud070 \ubc31\ubcf8\ub9dd\uc744 \ube44\ub85d\ud55c \ubb3c\ub9ac\uc801\uc778 \ub124\ud2b8\uc6cc\ud06c \ud658\uacbd\uc774 \uc608\uc804\uacfc \ub2e4\ub974\uac8c \ube44\uc57d\uc801\uc73c\ub85c \uc88b\uae30 \ub54c\ubb38\uc774\uc8e0.<\/span>
    BDP\uac00 \uc5b4\ub290 \uc815\ub3c4\ub85c \ud06c\ub0d0\uba74 receiver\uc758 receiver window size\ub97c \uc628\ub2f9\ud788 \uac10\ub2f9\ud560\ub9cc\ud07c \ud06c\ub2e4\uace0 \ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc989, \uc778\ud130\ub137\uc758 \uacbd\uc6b0 Bandwidth = (receiver window size) \/ RTT \uad00\uacc4\ub3c4 \uc131\ub9bd\ud55c\ub2e4\ub294 \uc774\uc57c\uae30\uc774\uc8e0.<\/span><\/p>\n\n<\/span>
    \ub2e4\uc2dc \uc815\ub9ac\ud558\uc790\uba74, \uc778\ud130\ub137\uc758 \uacbd\uc6b0 \ub300\uc5ed\ud3ed\uc744 \ub192\uc774\uae30 \uc704\ud574\uc11c\ub294 RTT\ub97c \ub0ae\ucd94\uac70\ub098 receiver window size\ub97c \ud0a4\uc6b0\uba74 \ub429\ub2c8\ub2e4.<\/span>
    \uadf8\ub7f0\ub370 RTT\ub294 peer\uac04 \ubb3c\ub9ac\uc801\uc778 \uac70\ub9ac\uc5d0 \uc885\uc18d\uc801\uc774\uc5b4\uc11c \ub0ae\ucd94\uae30 \ud798\ub4ed\ub2c8\ub2e4.<\/span>
    \uc989, \ub300\uc5ed\ud3ed\uc744 \ub192\uc774\ub824\uba74 receiver window size\ub97c \uc99d\uac00\uc2dc\ucf1c\uc57c \ud569\ub2c8\ub2e4.<\/span><\/strong><\/p>\n\n<\/span>
    \uadf8\ub807\ub2e4\uba74, receiver window size\ub97c \uc99d\uac00\ud558\ub824\uba74 \uc5b4\ub5bb\uac8c \ud574\uc57c \ud560\uae4c\uc694?<\/span><\/p>\n\n<\/span>
    3.2 TCP window scaling<\/span><\/h3>
    \uae30\ubcf8\uc801\uc73c\ub85c TCP \uc5f0\uacb0\uc744 \ub9fa\uc744 \ub54c, SYN \ud328\ud0b7\uc5d0\ub294 receiver window size\ub97c \uacf5\uace0(advertising) \ud558\ub3c4\ub85d \ub418\uc5b4 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    \uc774 \uac12\uc758 \ubc94\uc704\ub294 0~65,535\uae4c\uc9c0\uc778\ub370\uc694. \uc989, 64KB\uae4c\uc9c0 \uc9c0\uc815\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    \uc778\ud130\ub137\uc774 \ucc98\uc74c \ub098\uc62c\uc801\uc758 \uc608\uc804\uc774\ub77c\uba74 \ubaa8\ub974\uaca0\uc9c0\ub9cc, \uc9c0\uae08 \uc138\uc0c1\uc5d0\uc11c 64KB\ub294 \uaf64\ub098 \uc791\uc740 \ub370\uc774\ud130\uc591\uc774\uaca0\uc9c0\uc694.<\/span><\/p>\n\n<\/span>
    RFC 1323\uc5d0\uc11c\ub294 TCP window scaling\uc774\ub77c\ub294 \uc635\uc158\uc744 \uc815\uc758\ud558\uace0 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    TCP \ud5e4\ub354\uc758 \uc635\uc158 \ud544\ub4dc\uc5d0 window scale\ub77c\ub294 \ud544\ub4dc\ub97c \uc815\uc758\ud558\uc5ec advertise\ud560 \uc218 \uc788\ub294 receiver window size\ub97c \ud0a4\uc6b8 \uc218 \uc788\ub3c4\ub85d \ud569\ub2c8\ub2e4.<\/span><\/strong><\/p>\n\n<\/span>
    \uc774 \uac12\uc740 0~14\uae4c\uc9c0 \uc9c0\uc815\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4. \uadf8\ub9ac\uace0 \uc774 \uac12\uc744 n\uc774\ub77c \ud55c\ub2e4\uba74, 2^n \uac12\uc744 window scaling factor\ub77c\uace0 \ud569\ub2c8\ub2e4.<\/span>
    TCP window scaling\uc744 \uc124\uc815\ud558\uba74, \uc2e4\uc81c receiver window size\ub294 \uae30\uc874\uc758 window size \uac12\uacfc \uc774 window scaling factor\uc758 \uacf1\uc73c\ub85c \uad6c\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc608\ub97c \ub4e4\uc5b4, window size \uac12\uc774 8,192\uc774\uace0 window scale \uac12\uc774 8\uc774\ub77c\uba74 \uc2e4\uc81c receiver window size\ub294 8,192 * (2^8) = 2,097,152 \ubc14\uc774\ud2b8\uac00 \ub429\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \ucc38\uace0\ub85c, TCP window scaling\uc744 \uc0ac\uc6a9\ud560 \ub54c \ucd5c\ub300 receiver window size\ub294 65,535 * (2^14) = 1,073,725,440 \ubc14\uc774\ud2b8(1GB)\uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    TCP window scaling\uc744 \ud65c\uc131\ud654\ud558\ub824\uba74, \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130 '<\/span>net.ipv4.tcp_window_scaling<\/span><\/code>' \uac12\uc774 '<\/span>1<\/span><\/code>'\ub85c \uc124\uc815\ub418\uc5b4 \uc788\uc5b4\uc57c \ud569\ub2c8\ub2e4.<\/span>
    \ub2e4\uc74c\uacfc \uac19\uc740 \uba85\ub839\uc5b4\ub97c \uc0ac\uc6a9\ud558\uba74 \ud65c\uc131\ud654 \ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ sysctl -w net.ipv4.tcp_window_scaling=\"1\"\n<\/span><\/code><\/pre>
    \ucc38\uace0\ub85c, \ud1b5\uc2e0\ud558\ub294 \ub450 host \uc591 \uce21 \ubaa8\ub450 TCP window scaling \uc635\uc158\uc744 \ud65c\uc131\ud654\ud574\uc57c \uc62c\ubc14\ub974\uac8c \ub3d9\uc791\ud558\uac8c \ub429\ub2c8\ub2e4.<\/span>
    \uadf8\ub9ac\uace0 \uc77c\ubc18\uc801\uc73c\ub85c \ud074\ub77c\uc774\uc5b8\ud2b8 OS(Windows, MAC OS X, iOS, Android)\ub4e4\uc740 \uc774 \uc635\uc158\uc774 \ud65c\uc131\ud654\ub418\uc5b4 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    3.3 TCP socket buffer size<\/span><\/h3>
    TCP window scaling\uc744 \uc774\uc6a9\ud558\uc5ec receiver window size\uc758 \ud55c\uacc4\uce58\ub97c \uc99d\uac00\ud558\ub354\ub77c\ub3c4, \uc2e4\uc81c \ucee4\ub110\uc5d0 \uc124\uc815\ub41c \uc18c\ucf13 \ubc84\ud37c \ud06c\uae30\ubcf4\ub2e4 \ucee4\uc9c8 \uc218\ub294 \uc5c6\uc744 \uac83 \uc785\ub2c8\ub2e4.<\/span>
    \uacb0\uad6d receiver window size\ub97c \uc99d\uac00\ud558\uae30 \uc704\ud574\uc11c\ub294, \uc18c\ucf13\ub2f9 \ubc84\ud37c \ud06c\uae30\ub97c \uc99d\uac00\uc2dc\ucf1c\uc57c \ud569\ub2c8\ub2e4.<\/span><\/strong><\/p>\n\n<\/span>
    \uc774\uc640 \uad00\ub828\ub41c \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\ub294 \ub2e4\uc74c\uacfc \uac19\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    - net.core.rmem_default\n- net.core.wmem_default\n- net.core.rmem_max\n- net.core.wmem_max\n- net.ipv4.tcp_rmem\n- net.ipv4.tcp_wmem\n<\/span><\/code><\/pre>
    \uc5ec\uae30\uc11c rmem\uc740 receive(read) buffer\uc758 \ud06c\uae30, wmem\uc740 send(write) buffer\uc758 \ud06c\uae30\ub97c \ub098\ud0c0\ub0c5\ub2c8\ub2e4.<\/span>
    \uc9c0\uc815\ub418\ub294 \uac12\ub4e4\uc758 \ub2e8\uc704\ub294 \ubc14\uc774\ud2b8(bytes) \uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uba3c\uc800 net.core \uc811\ub450\uc0ac\uac00 \ubd99\uc740 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130 \ubd80\ud130 \uc0b4\ud3b4 \ubcf4\uaca0\uc2b5\ub2c8\ub2e4.<\/span>
    \uc774\ub294 TCP\ub97c \ud3ec\ud568\ud55c \ubaa8\ub4e0 \uc885\ub958\uc758 \uc18c\ucf13\uc5d0 \uae30\ubcf8\uc801\uc73c\ub85c \uc124\uc815\ub418\ub294 \ubc84\ud37c \ud06c\uae30\ub97c \ub098\ud0c0\ub0c5\ub2c8\ub2e4.<\/span>
    \uc811\ubbf8\uc0ac default\ub294 \uadf8 \uae30\ubcf8\uac12\uc774\uace0, max\ub294 \uc18c\ucf13\uc774 \uac00\uc9c8 \uc218 \uc788\ub294 \ucd5c\ub300 \ud06c\uae30\ub97c \ub098\ud0c0\ub0c5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    net.ipv4 \uc811\ub450\uc0ac\uac00 \ubd99\uc740 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\ub294 TCP \uc18c\ucf13\uc5d0 \ub300\ud55c \ubd80\ubd84\uc744 \uc124\uc815\ud569\ub2c8\ub2e4.<\/span>
    \ucc38\uace0\ub85c, \uc774 \uc124\uc815\uac12\uc740 ipv6\uc5d0\uc11c\ub3c4 \uc801\uc6a9\ub418\ub294\ub370, \ub9ac\ub205\uc2a4\uc5d0\uc11c\ub294 \uc77c\ubd80 ipv4 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\uac00 ipv6\uae4c\uc9c0 \uc801\uc6a9 \ub418\uae30 \ub54c\ubb38\uc785\ub2c8\ub2e4.<\/span>
    (ipv6\uc5d0\ub3c4 \uc801\uc6a9\ub418\ub294 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130: net.ipv4.ip_<\/span>, net.ipv4.ip_local_port<\/span>range, net.ipv4.tcp<\/span><\/em><\/em>, net.ipv4.icmp_*)<\/span><\/p>\n\n<\/span>
    \uac01 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\ub294 min \/ default \/ max\ub85c \uc138 \uc815\uc218 \uac12\uc73c\ub85c \uc124\uc815 \ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    min\uc740 TCP memory pressure \uc0c1\ud0dc\uc77c \ub54c \uc18c\ucf13\uc5d0 \ud560\ub2f9\ub418\ub294 \ubc84\ud37c \ud06c\uae30\ub97c \ub098\ud0c0\ub0b4\uace0\uc694, max\ub294 TCP \uc18c\ucf13\uc774 \uac00\uc9c8 \uc218 \uc788\ub294 \ucd5c\ub300 \ud06c\uae30\ub97c \ub098\ud0c0\ub0c5\ub2c8\ub2e4.<\/span>
    TCP memory pressure \uc0c1\ud0dc\uc5d0 \ub300\ud574\uc11c\ub294 \uc870\uae08 \ub354 \uc544\ub798\uc5d0\uc11c \ub2e4\ub8e8\ub3c4\ub85d \ud558\uaca0\uc2b5\ub2c8\ub2e4.<\/span>
    \uc911\uac04\uac12\uc740 default\ub85c net.core\uc5d0\uc11c \uc124\uc815\ub41c default \uac12\uc744 TCP \uc18c\ucf13\uc5d0 \ud55c\uc815\ud558\uc5ec \ub36e\uc5b4 \uc50c\uc6c1\ub2c8\ub2e4.<\/span>
    \ud2b9\ud788, default \uac12\uc740 TCP receive window \ud06c\uae30\ub97c \uacb0\uc815\ud560 \ub54c \uac00\uc7a5 \uc8fc\uc694\ud558\uac8c \ucc38\uc870\ub418\ub294 \uac12\uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc774 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\uc758 \uae30\ubcf8\uac12\uc740 \ub9ac\ub205\uc2a4 \ucee4\ub110\uc5d0 \uc758\ud558\uc5ec \uc790\ub3d9\uc73c\ub85c \uc124\uc815(auto-tuned)\ub418\ub098, \ub300\uac1c default \uac12\uc774 128KB \uc815\ub3c4\ub85c \uc124\uc815\ub418\uc5b4 \uc788\ub294\ub370\uc694.<\/span>
    \ube44\uad50\uc801 \uba54\ubaa8\ub9ac \uc591\uc774 \uc801\uace0, \ub300\uaddc\ubaa8\/\ub300\uc6a9\ub7c9 \ud328\ud0b7\ucc98\ub9ac\ub97c \ud558\uc9c0 \uc54a\ub294 \ub370\uc2a4\ud06c\ud0d1\uc5d0\uc11c\ub294 \uc801\ud569\ud55c \uc124\uc815\uc785\ub2c8\ub2e4.<\/span>
    \uc11c\ubc84\uc758 \uacbd\uc6b0 \uc77c\ubc18\uc801\uc73c\ub85c \uba54\ubaa8\ub9ac \uc591\uc774 \ud06c\uae30\uc5d0 \uc801\uc808\ud788 \ud06c\uae30\ub97c \ub298\ub824\uc918\ub3c4 \uc88b\uc744 \uac83 \uac19\uc2b5\ub2c8\ub2e4. (\ub124\ud2b8\uc6cc\ud06c \ub300\uc5ed\ud3ed - \uba54\ubaa8\ub9ac \uc0ac\uc6a9\ub7c9\uc758 trade-off)<\/span><\/p>\n\n<\/span>
    TCP receive window size\ub97c \uc99d\uac00\uc2dc\ud0a4\ub824\uba74, \uc704\uc5d0\uc11c \ub098\uc5f4\ud55c \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\ub97c \uc801\ub2f9\ud788 \uc124\uc815\ud574\uc57c \ud569\ub2c8\ub2e4.<\/span>
    \uc5b4\ub5a4 \uc6cc\ud06c\ub85c\ub4dc\uc5d0\uc11c\ub3c4 \uc801\uc6a9 \uac00\ub2a5\ud55c \uc644\ubcbd\ud55c \ucee4\ub110 \ud30c\ub9ac\ubbf8\ud130\ub294 \uc5c6\uc2b5\ub2c8\ub2e4.<\/span>
    \ub2e4\ub9cc \uc774 \uacbd\uc6b0 trade-off \uad00\uacc4\uac00 \uba54\ubaa8\ub9ac \uc0ac\uc6a9\ub7c9 \ubc16\uc5d0 \uc5c6\uae30\uc5d0, \uc544\ub798\uc640 \uac19\uc740 \uc124\uc815\uac12\uc744 \uc870\uc2ec\uc2a4\ub808 \uc81c\uc548\ud569\ub2c8\ub2e4.<\/span>
    (\uc801\ub2f9\ud788 \ubcf4\uc218\uc801\uc73c\ub85c \uc0c1\ud5a5\ub41c \uc124\uc815\uac12\uc785\ub2c8\ub2e4.)<\/span><\/p>\n\n<\/span>
    $ sysctl -w net.core.rmem_default=\"253952\"\n$ sysctl -w net.core.wmem_default=\"253952\"\n$ sysctl -w net.core.rmem_max=\"16777216\"\n$ sysctl -w net.core.wmem_max=\"16777216\"\n$ sysctl -w net.ipv4.tcp_rmem=\"253952 253952 16777216\"\n$ sysctl -w net.ipv4.tcp_wmem=\"253952 253952 16777216\"\n<\/span><\/code><\/pre>
    \uc774 \uc678\uc5d0 '<\/span>net.ipv4.tcp_mem<\/span><\/code>'\uc774\ub77c\ub294 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\uac00 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    \uc774 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\ub294 \ucee4\ub110\uc5d0\uc11c TCP\ub97c \uc704\ud574 \uc0ac\uc6a9\ud560 \uc218 \uc788\ub294 \uba54\ubaa8\ub9ac \ud06c\uae30\ub97c \uc9c0\uc815\ud569\ub2c8\ub2e4.<\/span>
    \uc704\uc5d0\uc11c \uc18c\uac1c\ud55c \ud30c\ub77c\ubbf8\ud130\ub4e4\uc740 \uac1c\ubcc4 TCP \uc18c\ucf13\ub2f9 \uc9c0\uc815\ub418\ub294 \uac12\uc774\ub77c\uba74, \uc774 \uac12\uc740 TCP \uc18c\ucf13 \uc804\uccb4\uc5d0 \ub300\ud55c \uac12\uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc774 \uc124\uc815\uac12\uc740 \uc704\uc5d0\uc11c \uc18c\uac1c\ud55c \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\ub4e4\uacfc \uc720\uc0ac\ud558\uac8c min \/ pressure \/ max \uac12\uc744 \uc9c0\uc815\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    \uc774 \uc911 pressure\ub294 net.ipv4.tcp_rmem, net.ipv4.tcp_wmem\uc5d0\uc11c \uc7a0\uae50 \uc5b8\uae09\ud55c memory pressure\uc758 threshold \uac12 \uc785\ub2c8\ub2e4.<\/span>
    \uc989, TCP \uc18c\ucf13 \uc804\uccb4\uc5d0\uc11c \uc0ac\uc6a9\ub418\ub294 \uba54\ubaa8\ub9ac\uac00 \uc774 \uac12\uc744 \ucd08\uacfc\ud558\uba74, TCP memory pressure \uc0c1\ud0dc\uac00 \ub418\uc5b4 \uc774\ud6c4 \uc18c\ucf13\uc740 \uc9c0\uc815\ub41c min \uac12\uc758 \uba54\ubaa8\ub9ac \ubc84\ud37c \ud06c\uae30\ub97c \uac00\uc9c0\uac8c \ub418\ub294 \uac83\uc774\uc8e0.<\/span><\/p>\n\n<\/span>
    \ub2e4\uc74c\uacfc \uac19\uc740 \uba85\ub839\uc5b4\ub85c \ud604\uc7ac \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130 \uc124\uc815\uac12\uc744 \ud655\uc778 \ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ sysctl net.ipv4.tcp_mem\nnet.ipv4.tcp_mem = 185688    247584    371376\n<\/span><\/code><\/pre>
    \uc704 \uac12\uc740 \ubd80\ud305\uc2dc \uc2dc\uc2a4\ud15c\uc758 \uba54\ubaa8\ub9ac\uc5d0 \ub9de\ucd94\uc5b4 \uc790\ub3d9\uc73c\ub85c(auto-tuned) \uc124\uc815\ub429\ub2c8\ub2e4.<\/span>
    \ud55c\uac00\uc9c0 \uc720\uc758\ud560 \uc810\uc740, \ub418\ub3c4\ub85d \uc774 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130 \uc124\uc815\uac12\uc744 \uc218\uc815\ud558\uc9c0 \ub9d0\uc544\uc57c \ud55c\ub2e4\ub294 \uc810 \uc785\ub2c8\ub2e4.<\/span>
    \uc65c\ub0d0\ud558\uba74, \uc774\ubbf8 \ucee4\ub110\uc5d0 \uc758\ud574 \uc2dc\uc2a4\ud15c \uba54\ubaa8\ub9ac\uc5d0 \ub9de\uac8c \ucd5c\uc801\ud654\ub41c \uac12\uc774 \uc124\uc815\ub418\uae30 \ub54c\ubb38\uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uad6c\uae00 \uac80\uc0c9 \ub4f1\uc73c\ub85c \ucc3e\uc744 \uc218 \uc788\ub294 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130 \uc124\uc815 \uad00\ub828 \ubb38\uc11c \uc911 \uc77c\ubd80\ub97c \uc0b4\ud3b4\ubcf4\uba74, \uc774 \uac12\uc744 \ub300\ud3ed \uc62c\ub9ac\ub3c4\ub85d \uac00\uc774\ub4dc \ud558\uae30\ub3c4 \ud558\ub294\ub370\uc694.<\/span>
    \uc27d\uc0ac\ub9ac \ucc3e\uc744 \uc218 \uc788\ub294 \uc5b4\ub5a4 \ubb38\uc11c\uc5d0\ub294 \ub2e4\uc74c\uacfc \uac19\uc774 \uac00\uc774\ub4dc \ud569\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ sysctl -w net.ipv4.tcp_mem=\"8388608 8388608 8388608\"\n<\/span><\/code><\/pre>
    \uc774 \uc124\uc815\uac12\uc774 \uc65c \ub9d0\uc774 \uc548\ub418\ub294 \uc124\uc815\uac12\uc774\ub0d0\uba74, \uadf8 \ub2e8\uc704\uac00 \ubc14\uc774\ud2b8(byte)\uac00 \uc544\ub2c8\ub77c \ud398\uc774\uc9c0(page)\uc774\uae30 \ub54c\ubb38\uc785\ub2c8\ub2e4.<\/span>
    \ub9ac\ub205\uc2a4\uc5d0\uc11c\ub294 \uae30\ubcf8\uc801\uc73c\ub85c 1 \ud398\uc774\uc9c0\ub294 4,096 \ubc14\uc774\ud2b8\uc785\ub2c8\ub2e4.<\/span>
    \uc989, \uc704 \uc124\uc815\uac12\ub300\ub85c \ub77c\uba74 8,388,608\uc740 32\uae30\uac00\ubc14\uc774\ud2b8\ub97c \ub73b \ud569\ub2c8\ub2e4. (\ucee4\ub3c4 \ub108\ubb34 \ud06c\uc8e0.)<\/span><\/p>\n\n<\/span>
    3.4 congestion window size<\/span><\/h3>
    \uadf8\ub7fc receiver\uac00 \uacf5\uace0(advertising)\ud55c receive window size \ub9cc\ud07c sender\ub294 \ub370\uc774\ud130\ub97c \ub124\ud2b8\uc6cc\ud06c\ub85c \ud328\ud0b7\uc744 \ubcf4\ub0bc \uc218 \uc788\uc744\uae4c\uc694?<\/span>
    \uacb0\ub860\ubd80\ud130 \ub9d0\ud558\uc790\uba74, \uadf8\ub807\uc9c0 \uc54a\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \ub124\ud2b8\uc6cc\ud06c\ub294 \ub124\ud2b8\uc6cc\ud06c\uc5d0 \uc5f0\uacb0\ub41c \ubaa8\ub4e0 \ub178\ub4dc\ub4e4\uac04 \uacf5\uc720\ud558\ub294 \uacf5\uc720 \uc790\uc6d0\uc785\ub2c8\ub2e4. \uac1c\uac1c \ub178\ub4dc\uac00 \uc774\ub97c \ud0d0\uc695\uc801\uc73c\ub85c \uc0ac\uc6a9\ud558\uba74, \ub124\ud2b8\uc6cc\ud06c \uc804\uccb4\uac00 \ub9c8\ube44\ub420 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    \uadf8\ub807\uae30 \ub54c\ubb38\uc5d0, \uac01 \ub178\ub4dc\ub4e4\uc740 \uc801\ub2f9\ud55c congestion avoidance algorithm\uc744 \uc0ac\uc6a9\ud558\uc5ec \ubcf4\ub0b4\ub294 \ub370\uc774\ud130 \uc591\uc744 \uc790\uccb4\uc801\uc73c\ub85c \uc870\uc815\ud558\uace0 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc774 congestion avoidance algorithm\uc740 receiver\uc640\ub294 \uc0c1\uad00\uc5c6\uc774 (receiver window size \ub4f1 peer\uac00 \uc54c\ub824\uc8fc\ub294 \uc815\ubcf4\uc640\ub294 \ubb34\uad00\ud558\uac8c) \ub3c5\uc790\uc801\uc73c\ub85c \ub124\ud2b8\uc6cc\ud06c\uc5d0 \ubcf4\ub0bc \ub370\uc774\ud130 \uc591\uc744 \uc815\ud569\ub2c8\ub2e4.<\/span>
    \ub9ac\ub205\uc2a4\uc5d0\uc11c\ub294 reno, vegas, new reno, bic, cubic \ub4f1\uc758 congestion avoidance algorithm\uc744 \uc0ac\uc6a9\ud560 \uc218 \uc788\ub294\ub370, \uc694\uc988\uc74c\uc758 \uc77c\ubc18\uc801\uc778 \ub9ac\ub205\uc2a4 \ubc30\ud3ec\ud310\uc5d0\uc11c\ub294 cubic\uac00 \uae30\ubcf8\uc801\uc73c\ub85c \uc124\uc815\ub418\uc5b4 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    congestion avoidance algorithm\uc740 \uba87 \uac00\uc9c0 \ud30c\ub77c\ubbf8\ud130\ub97c \ucc38\uc870(RTT\uac00 \uac00\uc7a5 \uc8fc\uc694\ud55c \ud30c\ub77c\ubbf8\ud130\uac00 \ub420 \uac83\uc785\ub2c8\ub2e4.)\ud558\uc5ec congestion window \ud06c\uae30\ub97c \uc124\uc815\ud558\uac8c \ub418\ub294\ub370\uc694. \uc774 \ud06c\uae30\uac00 \ud55c\ubc88\uc5d0 \ubcf4\ub0bc \uc218 \uc788\ub294 \ub370\uc774\ud130 \uc591\uc758 \ucd5c\ub300\uce58\uac00 \ub420 \uac83\uc785\ub2c8\ub2e4. congestion window \ud06c\uae30\ub294 \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc774\ub098 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\ub85c \uc124\uc815 \ub420 \uc218 \uc788\ub294 \uac12\uc740 \uc544\ub2d9\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \ub9ac\ub205\uc2a4\uc5d0\uc11c\ub294 ss\uc640 \uac19\uc740 \uc720\ud2f8\ub9ac\ud2f0\ub97c \ud1b5\ud574 \uac01 \uc18c\ucf13\ubcc4 \ud604\uc7ac congestion window \ud06c\uae30\ub97c \ud655\uc778\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ ss -n -i\n\nNetid State      Recv-Q Send-Q                                Local Address:Port                                                         Peer Address:Port\ntcp    ESTAB      0      0                                                                10.77.57.57:33000                                                           10.77.57.57:47142\n     cubic wscale:7,7 rto:208 rtt:5.236\/10.107 ato:40 mss:65483 cwnd:10 send 1000.5Mbps rcv_rtt:4 rcv_space:43690<\/span>\n<\/span><\/code><\/pre>
    \uc774 \uc18c\ucf13\uc740 congestion avoidance algorithm\uc73c\ub85c cubic\uc744 \uc0ac\uc6a9\ud558\uace0, \ud604\uc7ac congestion window size\uac00 10\uc784\uc744 \uc54c \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    \uc989, \ud55c\ubc88\uc5d0 \ubcf4\ub0bc \uc218 \uc788\ub294 \ud328\ud0b7 \uac1c\uc218\ub294 10\uac1c\uc774\uba70 \uc57d 15KB \uc815\ub3c4\uc758 \ub370\uc774\ud130\ub97c \ud55c\ubc88\uc5d0 \ubcf4\ub0bc \uc218 \uc788\uc744 \uac83\uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc774 congestion window size\ub294 TCP\uc758 \ud63c\uc7a1 \uc81c\uc5b4 \uc804\ub7b5\uc5d0 \ub530\ub77c slow start \ubc29\ubc95\uc73c\ub85c \ucd5c\ucd08 \uc5f0\uacb0\uc2dc \uc815\ud574\uc9c4 'initial congestion window size(CWND)'\ubd80\ud130 \uc5b4\ub290 \uc815\ub3c4 \uc120\uae4c\uc9c0 \uc9c0\uc18d\uc801\uc73c\ub85c \uc99d\uac00\ud558\uac8c \ub429\ub2c8\ub2e4.<\/span>
    \uadf8\ub9ac\uace0 \ud1b5\uc2e0\uc774 \uc9c0\uc18d\uc801\uc73c\ub85c \uc9c4\ud589\ub418\uba74\uc11c receiver\ub85c \ubd80\ud130 ACK \ud328\ud0b7\uc744 \ubc1b\uc73c\uba74, congestion window size\ub97c \ud604\uc7ac \ud06c\uae30\uc758 2\ubc30 \ub9cc\ud07c\uc529 \uc99d\uac00 \uc2dc\ud0b5\ub2c8\ub2e4.<\/span>
    (\uadf8 \uc640\uc911\uc5d0 \ud328\ud0b7\uc774 \uc720\uc2e4\ub418\uac70\ub098 \ud55c\ub2e4\uba74 congestion window size\ub97c \uac10\uc18c\uc2dc\ud0ac\ud150\ub370\uc694. \uc774\ub294 congestion avoidance algorithm\uc5d0 \ub530\ub77c \uc5bc\ub9c8\ub9cc\ud07c \uacbd\uac10\ud560\uc9c0 \ub2ec\ub77c\uc9d1\ub2c8\ub2e4.)<\/span><\/p>\n\n<\/span>
    \uadf8\ub7f0\ub370, \uc774\ub7ec\ud55c \ud2b9\uc131 \ub54c\ubb38\uc5d0 RTT\uac00 \ube44\uad50\uc801 \ub192\uc740 \ubaa8\ubc14\uc77c \ud658\uacbd\uc5d0\uc11c \ucde8\uc57d\ud55c \uba74\uc774 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc608\ub97c \ub4e4\uc5b4, receive window size\uac00 64KB\uc778 receiver\uac00 \uc788\ub2e4\uace0 \ud569\uc2dc\ub2e4. sender\uc758 initial congestion window\uac00 1\uc774\ub77c\uba74, congestion window size\uac00 64KB\uc5d0 \ub3c4\ub2ec\ud558\uae30 \uc704\ud574\uc11c\ub294 peer\ub85c \ubd80\ud130 6\ubc88\uc758 ACK\uc744 \ubc1b\uc544\uc57c \ud569\ub2c8\ub2e4.<\/span>
    \uc774 \ub54c RTT\uac00 500ms\ub77c\uba74 3\ucd08 \uc774\ud6c4\uc5d0\uc57c receive window size\ub9cc\ud07c congestion window size\uac00 \uc99d\uac00\ub420 \uac83\uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc774\ub7ec\ud55c \uc774\uc720 \ub54c\ubb38\uc5d0 \uad6c\uae00\uc5d0\uc11c\ub294 2010\ub144\uacbd TCP initial congestion window size\ub97c 10\uc73c\ub85c \uc0c1\ud5a5(\uc77c\ubc18\uc801\uc73c\ub85c 1 \ud639\uc740 2\ub85c \uc124\uc815) \ud558\uc790\ub294 \uc758\uacac\uc744 \ub0b4\ub193\uae30\ub3c4 \ud588\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uadf8\ub7ec\ub098 \ub2e4\uc2dc \ud55c\ubc88 \uc774\uc57c\uae30 \ud558\uc790\uba74, \ubaa8\ub4e0 \uc6cc\ud06c\ub85c\ub4dc\uc640 \uc870\uac74\uc744 \ub9cc\uc871\ud558\ub294 \uc124\uc815\uac12\uc740 \uc5c6\uc2b5\ub2c8\ub2e4.<\/span>
    \ub124\ud2b8\uc6cc\ud06c \uc0c1 \ubaa8\ub4e0 peer\ub4e4\uc774 initial congestion window size\ub97c 10\uc73c\ub85c \uc99d\uac00 \uc124\uc815\ud558\uace0, \ud56d\uc0c1 \uc774 \ud328\ud0b7\uc218\ubcf4\ub2e4 \ub9ce\uc740 \ud1b5\uc2e0\uc744 \ube48\ubc88\ud788 \ud558\uac8c \ub41c\ub2e4\uba74 \uc804\uccb4 \ub124\ud2b8\uc6cc\ud06c\uac00 \ud63c\uc7a1\ud55c \uc0c1\ud669\uc774 \ub418\ub294 \uc7ac\uc559\uc774 \ubc1c\uc0dd\ud560 \uc218\ub3c4 \uc788\uc744 \uac83\uc785\ub2c8\ub2e4.<\/span>
    \ub610, \ud55c\ubc88\uc5d0 \uc8fc\uace0 \ubc1b\ub294 \ud328\ud0b7 \ud06c\uae30\uac00 \uc0c1\ub300\uc801\uc73c\ub85c \uc791\ub2e4\uba74 initial congestion window size\ub97c \uc870\uc815\ud574\ub3c4 \ud06c\uac8c \uc774\ub4dd\uc774 \uc5c6\uc744 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    initial congestion window size\ub97c \ubcc0\uacbd\ud558\uae30 \uc704\ud574\uc11c\ub294, \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\uac00 \uc544\ub2c8\ub77c ip route \uba85\ub839\uc744 \uc0ac\uc6a9\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    \uba3c\uc800, \ud604\uc7ac\uc758 \ub77c\uc6b0\ud305 \uc815\ubcf4\ub97c \ud655\uc778\ud558\ub824\uba74 \uc544\ub798\uc640 \uac19\uc740 \uba85\ub839\uc5b4\ub97c \uc0ac\uc6a9\ud569\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ ip route show\n192.168.1.0\/24 dev eth0  proto kernel  scope link  src 192.168.1.100  metric 1 \n169.254.0.0\/16 dev eth0  scope link  metric 1000 \ndefault via 192.168.1.1 dev eth0  proto static\n<\/span><\/code><\/pre>
    \uc5ec\uae30\uc11c\ub294 default \ub77c\uc6b0\ud305 \uc124\uc815\uc744 \ubcc0\uacbd\ud560\ud150\ub370\uc694. \uc704\uc758 \uc124\uc815\uac12\uc744 \ud1a0\ub300\ub85c \uc544\ub798\uc640 \uac19\uc774 \uc785\ub825\ud558\uc5ec initial congestion window size\ub97c \ubcc0\uacbd\ud569\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ ip route change default via 192.168.1.1 dev eth0  proto static initcwnd 10\n<\/span><\/code><\/pre>
    \uc801\uc6a9\ub418\uc5c8\uc74c\uc744 \ud655\uc778\ud558\ub824\uba74, \uc544\ub798\uc640 \uac19\uc740 \uba85\ub839\uc5b4\ub97c \uc0ac\uc6a9\ud569\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ ip route show\n192.168.1.0\/24 dev eth0  proto kernel  scope link  src 192.168.1.100  metric 1 \n169.254.0.0\/16 dev eth0  scope link  metric 1000 \ndefault via 192.168.1.1 dev eth0  proto static  initcwnd 10\n<\/span><\/code><\/pre>
    \ucc38\uace0\ub85c \ud2b9\uc815 \ucee4\ub110 \ubc84\uc804(2.6.18)\uc5d0\uc11c\ub294 ethernet \uc124\uc815\uc5d0\uc11c TSO\ub97c \ud65c\uc131\ud654\ud558\uba74 \uc774 \uc218\uce58\uac00 \ubb34\uc2dc\ub418\ub294 \ubc84\uadf8\uac00 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    (\ube44\uad50\uc801 \uc624\ub798\ub41c \ucee4\ub110\uc774\ub77c \ucd5c\uadfc \ubc30\ud3ec\ud310\uc5d0\uc11c\ub294 \uad00\uacc4\uac00 \uc5c6\uc9c0\ub9cc, Redhat\/CentOS 5 \ubc84\uc804\uc774 \uc774 \ucee4\ub110\uc744 \uc0ac\uc6a9\ud569\ub2c8\ub2e4.)<\/span><\/p>\n\n<\/span>
    \ub610 \uc0b4\ud3b4\ubcfc \ub9cc\ud55c slow start\uc640 \uad00\ub828\ub41c \ub9ac\ub205\uc2a4 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\ub294 '<\/span>net.ipv4.tcp_slow_start_after_idle<\/span><\/code>' \uc785\ub2c8\ub2e4.<\/span>
    \uc774 \ud30c\ub77c\ubbf8\ud130\ub294 0 \ud639\uc740 1\ub85c \uc124\uc815\ud560 \uc218 \uc788\ub294\ub370\uc694.<\/span>
    1\ub85c \uc124\uc815\ub418\uc5b4 \uc788\uc73c\uba74 congestion window size\uac00 \uc99d\uac00\ub41c \uc18c\ucf13\uc774\ub77c\ub3c4 \ud2b9\uc815 \uc2dc\uac04 \ub3d9\uc548\uc758 idle(\ud1b5\uc2e0\uc774 \uc5c6\ub294) \uc0c1\ud0dc\uc5d0 \uc9c0\uc18d\ub418\uba74, \ub2e4\uc2dc slow start\ub97c \ud1b5\ud574 initial congestion window size\uc5d0\uc11c \ubd80\ud130 congestion window size\ub97c \uc99d\uac00\ud574\uc57c \ud569\ub2c8\ub2e4.<\/span>
    \ubc18\ub300\ub85c 0\uc73c\ub85c \uc124\uc815\ub418\uc5b4 \uc788\uc73c\uba74, \uc77c\uc815 \uc2dc\uac04 \ud1b5\uc2e0\uc774 \uc5c6\ub354\ub77c\ub3c4 congestion window size\uac00 \uc720\uc9c0 \ub429\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>

    <\/p>\n\n<\/span>
    \ubaa9\ucc28 - 2\ud3b8<\/span><\/h2>
    4. \ub124\ud2b8\uc6cc\ud06c capacity \uad00\ub828 \ud30c\ub77c\ubbf8\ud130\n    4.1 maximum file count\n    4.2 backlogs\n    4.3 port range\n<\/span><\/code><\/pre>
    4. \ub124\ud2b8\uc6cc\ud06c capacity \uad00\ub828 \ud30c\ub77c\ubbf8\ud130<\/span><\/h2>
    4.1 maximum file count<\/span><\/h3>
    \ub9ac\ub205\uc2a4\ub97c \ube44\ub86f\ud55c \uc77c\ubc18\uc801\uc778 \uc720\ub2c9\uc2a4\uc5d0\uc11c \uc18c\ucf13\uc740 \ub9c8\uce58 \ud30c\uc77c\uacfc \uac19\uc740 \ucde8\uae09\uc744 \ubc1b\uc2b5\ub2c8\ub2e4.<\/span>
    \uc804\uccb4 \uc2dc\uc2a4\ud15c\uc5d0\uc11c \uac00\uc9c8 \uc218 \uc788\ub294 \ud30c\uc77c \uac1c\uc218\uac00 \uc81c\ud55c\uc774 \uc788\ub2e4\uba74, \ub2f9\uc5f0\ud788 \uc18c\ucf13\uc758 \uc804\uccb4 \uac1c\uc218\uc5d0 \uc601\ud5a5 \ubbf8\uce60 \uac83 \uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \ub9ac\ub205\uc2a4\uc5d0\uc11c \uc804\uccb4 \uc2dc\uc2a4\ud15c\uc774 \uac00\uc9c8 \uc218 \uc788\ub294 \ucd5c\ub300 \ud30c\uc77c \uac1c\uc218 \uc81c\ud55c\uc740 '<\/span>fs.file-max<\/span><\/code>' \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\uc5d0\uc11c \uc124\uc815 \ub429\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \ud604\uc7ac \uc124\uc815\uac12\uc744 \ud655\uc778\ud558\ub824\uba74, \uc544\ub798\uc640 \uac19\uc740 \uba85\ub839\uc5b4\ub97c \uc0ac\uc6a9\ud569\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ sysctl fs.file-max\nfs.file-max = 775052\n<\/span><\/code><\/pre>
    \uc774 \uac12\uc740 \uc77c\ubc18\uc801\uc73c\ub85c \uc801\ub2f9\ud788 \ud070 \uac12\uc774 \uc124\uc815\ub418\uc5b4 \uc788\uc73c\ubbc0\ub85c, \uc6ec\ub9cc\ud558\uba74 \uc190 \ubcfc \uc77c\uc774 \uc5c6\uc744 \uac83\uc785\ub2c8\ub2e4.<\/span>
    \ub2e4\ub9cc, \uc2dc\uc2a4\ud15c\uc774 \uad49\uc7a5\ud788 \ub9ce\uc740 \ud30c\uc77c\uacfc \uc18c\ucf13\uc744 \uc0ac\uc6a9\ud558\ub294 \uacbd\uc6b0, \uc774 \uac12\uc5d0 \uc758\ud574 \uc2dc\uc2a4\ud15c\uc774 \uc624\ub3d9\uc791 \ud560 \uc218 \uc788\uc73c\ub2c8 \ucc38\uace0\ubc14\ub78d\ub2c8\ub2e4.<\/span>
    (\uc774 \uac12\uc744 \ub118\uc5b4\uac00\uba74 open() \uc2dc\uc2a4\ud15c \ucf5c\uc5d0\uc11c '<\/span>Too many open files<\/span><\/code>'\uc640 \uac19\uc740 \uc5d0\ub7ec\uac00 \ubc1c\uc0dd \ub420 \uac83 \uc785\ub2c8\ub2e4.)<\/span><\/p>\n\n<\/span>
    \ub2e4\uc2dc \ub9d0\ud558\uc790\uba74, \uc2dc\uc2a4\ud15c \uc804\uccb4\uc5d0 \ub300\ud55c \ud5c8\uc6a9 \uc18c\ucf13 \uac1c\uc218\ub294 '<\/span>fs-file-max<\/span><\/code>' \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130 \uc124\uc815\uac12\uc774 \uc801\ub2f9\ud788 \ub192\uac8c \uc124\uc815\ub418\uc5b4 \uc788\uc73c\ubbc0\ub85c \ud070 \ubb38\uc81c\uac00 \uc548\ub429\ub2c8\ub2e4.<\/span>
    \uc0ac\uc2e4, \uc5b4\ub5a4 \ud504\ub85c\uc138\uc2a4\uac00 \uac00\uc9c8 \uc218 \uc788\ub294 \uc18c\ucf13 \uac1c\uc218 \uc81c\uc57d\uc740 \uadf8\ubcf4\ub2e4\ub294 \ud504\ub85c\uc138\uc2a4\ubcc4 \uc81c\ud55c \uc124\uc815\uc778 user limit \uac12\uc744 \uc0b4\ud3b4\ubd10\uc57c \ud560 \uac83 \uc785\ub2c8\ub2e4.<\/span>
    \ub2e4\uc74c\uacfc \uac19\uc740 \uba85\ub839\uc5b4\ub85c \uc774\ub97c \ud655\uc778\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ ulimit -a\ncore file size          (blocks, -c) 0\ndata seg size           (kbytes, -d) unlimited\nscheduling priority             (-e) 0\nfile size               (blocks, -f) unlimited\npending signals                 (-i) 30473\nmax locked memory       (kbytes, -l) 64\nmax memory size         (kbytes, -m) unlimited\nopen files                      (-n) 1024\npipe size            (512 bytes, -p) 8\nPOSIX message queues     (bytes, -q) 819200\nreal-time priority              (-r) 0\nstack size              (kbytes, -s) 8192\ncpu time               (seconds, -t) unlimited\nmax user processes              (-u) 30473\nvirtual memory          (kbytes, -v) unlimited\nfile locks                      (-x) unlimited<\/span>\n<\/span><\/code><\/pre>
    \uc5ec\uae30\uc11c open files\uac00 \ud504\ub85c\uc138\uc2a4\uac00 \uac00\uc9c8 \uc218 \uc788\ub294 \uc18c\ucf13 \ud3ec\ud568 \ud30c\uc77c \uac1c\uc218\uc785\ub2c8\ub2e4.<\/span>
    \uc801\ub2f9\ub7c9 \uc99d\uac00\uc2dc\ud0a4\uae30 \uc704\ud574\uc11c\ub294 \ub2e4\uc74c\uacfc \uac19\uc740 \uba85\ub839\uc5b4\ub97c \uc0ac\uc6a9\ud569\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ ulimit -SHn 65535\n<\/span><\/code><\/pre>
    \ub9ce\uc740 \uac1c\uc218\uc758 \uc18c\ucf13\uc744 \uc0ac\uc6a9\ud558\ub294 \uc11c\ubc84 \ud504\ub85c\uadf8\ub7a8\uc740 \uad6c\ub3d9\ud558\uae30 \uc804, ulimit \uba85\ub839\uc5b4\ub85c \ud504\ub85c\uc138\uc2a4 \ub2f9 \ucd5c\ub300 \ud30c\uc77c \uac1c\uc218\ub97c \uc99d\uac00\uc2dc\ucf1c\uc8fc\uc5b4\uc57c \ud560 \uac83 \uc785\ub2c8\ub2e4.<\/span>
    (\ud639\uc740, \ud574\ub2f9 \uc560\ud50c\ub9ac\ucf00\uc774\uc158 \ub85c\uc9c1\ub0b4\uc5d0\uc11c setrlimit() \uc2dc\uc2a4\ud15c \ucf5c\ub85c \uc774\ub97c \uc99d\uac00\uc2dc\ud0a4\ub294 \ubc29\ubc95\ub3c4 \uc788\uc2b5\ub2c8\ub2e4.)<\/span><\/p>\n\n<\/span>
    '<\/span>fs.file-max<\/span><\/code>'\uc640 \uc720\uc0ac\ud55c \uc774\ub984\uc758 '<\/span>fs.file-nr<\/span><\/code>'\uc774\ub77c\ub294 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\uac00 \uc788\ub294\ub370, \uc0ac\uc2e4 \uc774 \ud30c\ub77c\ubbf8\ud130\ub294 \uc77c\ubc18\uc801\uc778 \ud30c\ub77c\ubbf8\ud130\uac00 \uc544\ub2c8\ub77c \ud604\uc7ac \uc5f4\ub824 \uc788\ub294 \ud30c\uc77c \ud604\ud669\uc744 \ub098\ud0c0\ub0c5\ub2c8\ub2e4.<\/span>
    \uc544\ub798\uc640 \uac19\uc740 \uba85\ub839\uc5b4\ub85c \ud604\uc7ac \ud604\ud669\uc744 \uc54c \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ sysctl fs.file-nr\nfs.file-nr = 5024    0    775052\n<\/span><\/code><\/pre>
    \uc138 \uac12\uc740 \uac01\uac01 \ud604\uc7ac \uc5f4\ub824 \uc788\ub294 \ud30c\uc77c\uc758 \uc218, \ud604\uc7ac \uc5f4\ub824 \uc788\uc73c\ub098 \uc0ac\uc6a9\ub418\uc9c0 \uc54a\ub294 \ud30c\uc77c\uc758 \uc218, \uc5f4 \uc218 \uc788\ub294 \ud30c\uc77c\uc758 \ucd5c\ub300 \uac1c\uc218\ub97c \ub73b\ud569\ub2c8\ub2e4. \ubb3c\ub860 \uc2dc\uc2a4\ud15c \uc804\uccb4\uc5d0 \ub300\ud55c \uc218\uce58\uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    4.2 backlogs<\/span><\/h2>
    \ub124\ud2b8\uc6cc\ud06c \ud328\ud0b7\uc740 \uadf8 \uc0dd\uc131\uac00 \uc804\ub2ec, \uadf8\ub9ac\uace0 \uc18c\ubaa8\uc5d0 \uc774\ub974\uae30\uae4c\uc9c0 \ub9ce\uc740 \ucc98\ub9ac \uacfc\uc815\uc744 \uac70\uce58\uac8c \ub429\ub2c8\ub2e4. \uac01\uac01\uc758 \ucc98\ub9ac \uacfc\uc815\uc744 \ud30c\uc774\ud504\ub77c\uace0 \ubcf8\ub2e4\uba74, \ubaa8\ub4e0 \ucc98\ub9ac \uacfc\uc815 \uc55e\uc5d0\ub294 \uac01\uac01 queue\uac00 \uc874\uc7ac\ud55c\ub2e4\uace0 \ud560 \uc218 \uc788\uc744 \uac83 \uc785\ub2c8\ub2e4. \ub124\ud2b8\uc6cc\ud06c \ud328\ud0b7 \ucc98\ub9ac\ub7c9\uc774 \uac11\uc790\uae30 \uae09\uc99d\ud588\uc744 \ub54c, \uc774 queue\uc758 \ud06c\uae30\uac00 \uc774\ubcf4\ub2e4 \uc791\ub2e4\uba74 \ub118\uce58\ub294 \ud328\ud0b7\uc5d0 \ub300\ud574\uc11c\ub294 \ucc98\ub9ac\ub418\uc9c0 \uc54a\uace0 \ubc84\ub824\uc9c8 \uac83 \uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc11c\ubc84 \ucee4\ub110 \uc124\uc815\uac12\uc5d0 \uc788\uc5b4 out-bound queue \ubcf4\ub2e4\ub294 in-bound queue\uac00 \ub354 \ubbfc\uac10\ud55c\ub370, \uc65c\ub0d0\ud558\uba74 out-bound\ub85c \ubcf4\ub0b4\uc9c0\ub294 \ud328\ud0b7\ub7c9\uc740 \uc11c\ubc84 \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc5d0\uc11c \uc870\uc808\ud560 \uc218 \uc788\uae30 \ub54c\ubb38\uc785\ub2c8\ub2e4. (\uac01\uac01\uc758 \uc694\uccad\uc740 \uadf8 \ucc98\ub9ac \uc2dc\uac04\uc774 \ub2e4\ub974\uae30\uc5d0 out-bound\uc2dc \uc801\ub2f9\ud788 \ub79c\ub364\ud558\uac8c \ubd84\ubc30\ub418\ub294 \ud6a8\uacfc\ub3c4 \uc788\uc2b5\ub2c8\ub2e4.)<\/span>
    \ub610, in-bound queue\uac00 \ub118\ucc98\uc11c \ubc84\ub824\uc9c0\ub294 \ud328\ud0b7\uc740 \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc5d0\uc11c \uc804\ud600 \uc54c \uc218 \uc5c6\uae30 \ub54c\ubb38\uc5d0 \ub300\uaddc\ubaa8 \ud328\ud0b7 \ucc98\ub9ac\uac00 \ud544\uc694\ud55c \uc11c\ubc84\uc5d0\uc11c\ub294 \uc801\ub2f9\ud788 in-bound queue \uae38\uc774\ub97c \uc99d\uac00\uc2dc\ucf1c\uc57c \ud569\ub2c8\ub2e4.<\/span><\/strong><\/p>\n\n<\/span>
    \uba3c\uc800 '<\/span>net.core.netdev_max_backlog<\/span><\/code>' \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\uc5d0 \ub300\ud574 \uc54c\uc544\ubd05\uc2dc\ub2e4.<\/span>
    \uc774 \ud30c\ub77c\ubbf8\ud130\ub294 \uac01 \ub124\ud2b8\uc6cc\ud06c \uc7a5\uce58 \ubcc4\ub85c \ucee4\ub110\uc774 \ucc98\ub9ac\ud558\ub3c4\ub85d \uc313\uc544\ub450\ub294 queue\uc758 \ud06c\uae30\ub97c \uc124\uc815\ud569\ub2c8\ub2e4. \ucee4\ub110\uc758 \ud328\ud0b7 \ucc98\ub9ac \uc18d\ub3c4\uac00 \uc774 queue\uc5d0 \ucd94\uac00\ub418\ub294 \ud328\ud0b7\uc758 \uc778\uc785 \uc18d\ub3c4\ubcf4\ub2e4 \ub5a8\uc5b4\uc9c4\ub2e4\uba74 \ubbf8\ucc98 queue\uc5d0 \ucd94\uac00\ub418\uc9c0 \ubabb\ud55c \ud328\ud0b7\ub4e4\uc740 \ubc84\ub824\uc9c8 \uac83\uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc774 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\ub3c4 trade-off \uad00\uacc4\uac00 \uba54\ubaa8\ub9ac \uc0ac\uc6a9\ub7c9 \ubc16\uc5d0 \uc5c6\uc73c\ubbc0\ub85c, \uc801\ub2f9\ud788 \uc99d\uac00\uc2dc\ucf1c\ub450\ub294 \uac83\ub3c4 \uad1c\ucc2e\uc2b5\ub2c8\ub2e4.<\/span>
    \ub2e4\uc74c\uacfc \uac19\uc740 \uba85\ub839\uc5b4\ub85c \uc124\uc815\uac12\uc744 \uc801\ub2f9\ud788 \uc99d\uac00 \uc2dc\ud0ac \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ sysctl -w net.core.netdev_max_backlog=\"30000\"\n<\/span><\/code><\/pre>
    \uad6c\uae00\uc5d0\uc11c \ucc3e\uc744 \uc218 \uc788\ub294 \uba87 \ucee4\ub110 \ud30c\ub9ac\ubbf8\ud130 \ud29c\ub2dd \uad00\ub828 \uae00\uc5d0\ub294, \uc774 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\uac00 listen backlog\ub77c\uace0 \uc798\ubabb \uc18c\uac1c\ub418\uae30\ub3c4 \ud558\ub294 \uac83 \uac19\uc2b5\ub2c8\ub2e4.<\/span>
    listen backlog, \uc989 listen()\uc73c\ub85c \ubc14\uc778\ub529 \ub41c \uc11c\ubc84 \uc18c\ucf13\uc5d0\uc11c accept()\ub97c \uae30\ub2e4\ub9ac\ub294 \uc18c\ucf13 \uac1c\uc218\uc5d0 \uad00\ub828\ub41c \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\ub294 '<\/span>net.core.somaxconn<\/span><\/code>'\uc785\ub2c8\ub2e4.<\/span>
    \uc774 \uac12\uc740 listen() \uc2dc\uc2a4\ud15c \ucf5c\uc758 \ub9e4\uac1c\ubcc0\uc218\ub85c \uc124\uc815\ud558\ub294 backlog \uac12\uc758 hard limit\uc785\ub2c8\ub2e4. \uc11c\ubc84 \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc5d0\uc11c listen()\uc2dc \uc801\ub2f9\ud788 \uc124\uc815\ud574\uc57c\uaca0\uc9c0\ub9cc, \uba3c\uc800 \uc774 hard limit\uc744 \uc99d\uac00\uc2dc\ucf1c\uc57c \ud560 \uac83\uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \ub2e4\uc74c\uacfc \uac19\uc740 \uba85\ub839\uc5b4\ub85c \uc774 \uc124\uc815\uac12\uc744 \uc99d\uac00 \uc2dc\ud0ac \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ sysctl -w net.core.somaxconn=\"1024\"\n<\/span><\/code><\/pre>
    \ucc38\uace0\ub85c, \uc77c\ubc18\uc801\uc778 \ub9ac\ub205\uc2a4 \ubc30\ud3ec\ud310\uc758 \uae30\ubcf8 \uc124\uc815\uac12\uc740 128\uc785\ub2c8\ub2e4. \uadf8\ub7f0\ub370, \uc544\ud30c\uce58 \uc6f9 \uc11c\ubc84\uc758 \uacbd\uc6b0 listen()\uc2dc \uc9c0\uc815\ub418\ub294 backlog\uc758 \uae30\ubcf8\uac12\uc774 511\uc785\ub2c8\ub2e4. \ud558\uc9c0\ub9cc \uc774 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\uac00 hard limit\uc774\uae30\uc5d0 \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc5d0\uc11c 511\uc73c\ub85c \uc9c0\uc815\ub418\uc5c8\ub354\ub77c\ub3c4 \uc2e4\uc81c\ub85c \ud560\ub2f9\ub418\ub294 listen backlog\uc758 \uc218\ub294 128\uac1c\uac00 \ub420 \uac83 \uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \ub610, <\/span>'net.ipv4.tcp_max_syn_backlog<\/span><\/code>'\ub77c\ub294 listen backlog\uc640 \uc5f0\uad00\ub41c \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\uac00 \uc788\uc2b5\ub2c8\ub2e4. '<\/span>net.core.somaxconn<\/span><\/code>'\uc774 accept()\uc744 \uae30\ub2e4\ub9ac\ub294 ESTABLISHED \uc0c1\ud0dc\uc758 \uc18c\ucf13(\uc989, connection completed)\uc744 \uc704\ud55c queue\ub77c\uba74, '<\/span>net.ipv4.tcp_max_syn_backlog<\/span><\/code>'\ub294 SYN_RECEIVED \uc0c1\ud0dc\uc758 \uc18c\ucf13(\uc989, connection incompleted)\uc744 \uc704\ud55c queue\uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc774 \uc124\uc815\uac12\ub3c4 \uc544\ub798\uc640 \uac19\uc774 \uc801\ub2f9\ud788 \uc99d\uac00 \uc2dc\ud0b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ sysctl -w net.ipv4.tcp_max_syn_backlog=\"1024\"\n<\/span><\/code><\/pre>
    \ud55c\uac00\uc9c0 \uc720\uc758\ud560 \uc810\uc740 \ucee4\ub110 \ud30c\ub9ac\ubbf8\ud130 \uc124\uc815\uac12\uc744 \uc0c1\ud5a5\ud558\ub354\ub77c\ub3c4, \uc2e4\uc81c \uc11c\ubc84 \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc5d0\uc11c listen backlog\ub97c \uc99d\uac00\uc2dc\ud0a4\ub824\uba74 listen() \uc2dc\uc2a4\ud15c \ucf5c \ud638\ucd9c\uc2dc \ub9e4\uac1c\ubcc0\uc218 backlog\uc5d0 \ud544\uc694\ud55c \uac12\uc744 \uc804\ub2ec\ud574\uc57c \ud569\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    4.3 port range<\/span><\/h3>
    TCP \uc5f0\uacb0\uc744 \ub9fa\uc744\ub54c, \ud074\ub77c\uc774\uc5b8\ud2b8 \uc18c\ucf13\uc740 \ud558\ub098\uc758 \ud3ec\ud2b8\ub97c \uc120\uc810\ud574\uc57c \ud569\ub2c8\ub2e4. TCP \uc5f0\uacb0\uc740 \ucd9c\ubc1c\uc9c0(source) \uc8fc\uc18c, \ucd9c\ubc1c\uc9c0 \ud3ec\ud2b8, \ubaa9\uc801\uc9c0(destination) \uc8fc\uc18c, \ubaa9\uc801\uc9c0 \ud3ec\ud2b8\ub97c \uadf8 \uad6c\ubd84\uc790\ub85c \ud558\uae30 \uc788\uae30 \ub54c\ubb38\uc785\ub2c8\ub2e4. \ud074\ub77c\uc774\uc5b8\ud2b8\uc5d0\uc11c \uc11c\ubc84\ub85c \uc5f0\uacb0\uc744 \ub9fa\uc744\ub54c, \ud2b9\ubcc4\ud788 bind() \uc2dc\uc2a4\ud15c \ucf5c\ub85c \ucd9c\ubc1c\uc9c0 \ud3ec\ud2b8\ub97c \uc9c0\uc815(bind)\ud558\uc9c0 \uc54a\ub294\ub2e4\uba74, \ucee4\ub110\uc740 \uc784\uc758\uc758 \ud3ec\ud2b8\ub97c \ud560\ub2f9\ud569\ub2c8\ub2e4.<\/span>
    \uadf8\ub9ac\uace0 \uc774\ub7ec\ud55c \ud3ec\ud2b8\ub97c ephemeral port\ub77c\uace0 \ud1b5\uce6d\ud569\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc989, \ud074\ub77c\uc774\uc5b8\ud2b8 \uc18c\ucf13\uc740 \uc11c\ubc84\uc5d0 \uc5f0\uacb0\uc744 \ub9fa\uc744\ub54c \ud3ec\ud2b8\ub77c\ub294 \uc790\uc6d0\uc744 \ud558\ub098 \uc18c\ubaa8\ud558\uba70, \ud3ec\ud2b8\ub294 \uc720\ud55c\ud55c \uc790\uc6d0\uc774\uae30\uc5d0 \ud55c \uc2dc\uc2a4\ud15c\uc5d0\uc11c \ub3d9\uc2dc\uc5d0 \uac00\uc9c8 \uc218 \uc788\ub294 \ud074\ub77c\uc774\uc5b8\ud2b8 \uc18c\ucf13\uc758 \uc218\ub294 \ud55c\uc815\uc801\uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \ubc18\ub300\ub85c, listen()\uc73c\ub85c \ud074\ub77c\uc774\uc5b8\ud2b8\uc758 \uc694\uccad\uc744 \uae30\ub2e4\ub9ac\uace0 \uc788\ub294 \uc11c\ubc84 \ud3ec\ud2b8\ub294 TCP \uc5f0\uacb0\uc744 \ub9fa\uc744 \ub54c \ucd94\uac00\uc801\uc778 \ud3ec\ud2b8\ub97c \uc18c\ubaa8\ud558\uc9c0 \uc54a\uc2b5\ub2c8\ub2e4.<\/span>
    \ub54c\ubb38\uc5d0 \uc77c\ubc18\uc801\uc778 \uc11c\ubc84\uc5d0\uc11c\ub294 \uac00\uc9c8 \uc218 \uc788\ub294 \ud3ec\ud2b8 \uc218\uc640 \uc11c\ubc84\uc758 \ud074\ub77c\uc774\uc5b8\ud2b8 \ub3d9\uc2dc \uc5f0\uacb0 \uc218\ub294 \ud06c\uac8c \uad00\uacc4\uac00 \uc5c6\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \ub2e4\ub9cc, \uc11c\ubc84\uc758 \uc720\ud615 \uc911 proxy \uc11c\ubc84\uc5d0 \ub300\ud574\uc11c \uc0dd\uac01\ud574 \ubcfc \ud544\uc694\uac00 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    \uc0ac\uc6a9\uc790(\ud074\ub77c\uc774\uc5b8\ud2b8)\ub85c \ubd80\ud130 \uc694\uccad\uc744 \ubc1b\uc544, \uc774\ub97c \ub2e4\ub978 \ubc31\uc5d4\ub4dc \uc11c\ubc84\uc5d0 \uc804\ub2ec\ud558\ub294 \uc720\ud615\uc758 \uc11c\ubc84\ub97c \ub9d0\ud558\ub294\ub370\uc694. \uc774 \uacbd\uc6b0 \ud574\ub2f9 \uc11c\ubc84\ub294 \ub2e4\ub978 \ubc31\uc5d4\ub4dc \uc11c\ubc84\uc5d0 \uc5f0\uacb0\ud558\uae30 \uc704\ud55c \ud074\ub77c\uc774\uc5b8\ud2b8 \uc18c\ucf13\uc774 \ud544\uc694\ud569\ub2c8\ub2e4.<\/span>
    \ub9cc\uc57d, \uc0ac\uc6a9\uc790 \uc694\uccad\uc774 \ub3d9\uc2dc\uc5d0 10,000\uac1c \ub4e4\uc5b4\uc624\ub294\ub370 \ud574\ub2f9 \uc11c\ubc84\uac00 \uac00\uc9c8 \uc218 \uc788\ub294 \ud074\ub77c\uc774\uc5b8\ud2b8 \uc18c\ucf13 \uc218\uac00 \ub3d9\uc2dc\uc5d0 100\uac1c\ub77c\uba74 9,900\uac1c\uc758 \uc694\uccad\uc740 \ucc98\ub9ac\ub418\uc9c0 \ubabb\ud558\uace0 \ub300\uae30\ud574\uc57c \ud560 \uac83 \uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc5b4\ub5a4 \uc2dc\uc2a4\ud15c\uc5d0 \ub3d9\uc2dc\uc5d0 \uac00\uc9c8 \uc218 \uc788\ub294 \ud074\ub77c\uc774\uc5b8\ud2b8 \uc18c\ucf13 \uc218\ub97c \uacb0\uc815\ud558\ub294 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\ub294 '<\/span>net.ipv4.ip_local_port_range<\/span><\/code>' \uc785\ub2c8\ub2e4.<\/span>
    \ucee4\ub110\uc740 ephemeral port\ub97c \uc0dd\uc131\ud560 \ub54c \uc774 \ubc94\uc704\ub0b4 \uc0ac\uc6a9\ud558\uc9c0 \uc54a\ub294 \ud3ec\ud2b8\ub97c \uace8\ub77c \ud560\ub2f9\ud558\uac8c \ub429\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \ub2e4\uc74c\uacfc \uac19\uc740 \uba85\ub839\uc5b4\ub97c \ud1b5\ud574 \ud604\uc7ac \uc124\uc815\uac12\uc744 \ud655\uc778\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ sysctl net.ipv4.ip_local_port_range\nnet.ipv4.ip_local_port_range = 32768    61000\n<\/span><\/code><\/pre>
    \uc704\uc5d0\uc11c \ub450 \uac12\uc740 \uac01\uac01 \uc0ac\uc6a9\ud560 \ud3ec\ud2b8 \ubc94\uc704\uc758 \uc2dc\uc791\uacfc \ub05d\uc744 \ub098\ud0c0\ub0c5\ub2c8\ub2e4. \uc774 \uc2dc\uc2a4\ud15c\uc5d0\uc11c\ub294 \ucd5c\ub300 28,232\uac1c\uc758 ephemeral port\ub97c \ud560\ub2f9\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    \ucd5c\ub300\ud55c \ub113\uc740 ephemeral port \ubc94\uc704\ub97c \uac00\uc9c0\ub824\uba74 \uc544\ub798\uc640 \uac19\uc740 \uba85\ub839\uc5b4\ub97c \uc0ac\uc6a9\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4. (well-known port\ub294 \uc81c\uc678)<\/span><\/p>\n\n<\/span>
    $ sysctl -w net.ipv4.ip_local_port_range=\"1024 65535\"\n<\/span><\/code><\/pre>
    \uadf8\ub7f0\ub370, \uc774\ub807\uac8c \uc124\uc815\ud558\ub354\ub77c\ub3c4 \uc2e4\uc81c \uc2dc\uc2a4\ud15c\uc5d0\uc11c \ub3d9\uc2dc\uc5d0 \uac00\uc9c8 \uc218 \uc788\ub294 \ud074\ub77c\uc774\uc5b8\ud2b8 \uc18c\ucf13 \uc218\ub294 \uc774\uc5d0 \ubbf8\uce58\uc9c0 \ubabb\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    TCP \uc5f0\uacb0\uc740 \uad49\uc7a5\ud788 \uacb0\ud569\ub3c4\uac00 \ub0ae\uc740 \ub124\ud2b8\uc6cc\ud06c \ud658\uacbd\uc744 \uac00\uc815\ud558\uace0 \uc788\uc2b5\ub2c8\ub2e4. \ub54c\ubb38\uc5d0 \ub124\ud2b8\uc6cc\ud06c \uc0c1\ud669\uc5d0 \uc758\ud574 \ud328\ud0b7 \uc21c\uc11c\uac00 \ub4a4\ubc14\ub00c\uac70\ub098 \uc720\uc2e4 \ub418\ub294 \ub4f1\uc758 \ucc98\ub9ac\ub97c \uc704\ud574, \uc18c\ucf13 \uc885\ub8cc\uc2dc\uc5d0\ub3c4 \ub418\ub3c4\ub85d \uc6b0\uc544\ud558\uac8c \uc885\ub8cc(gracefully shutdown)\ud558\ub3c4\ub85d \ub418\uc5b4 \uc788\ub294\ub370\uc694. \uc774 \uc598\uae30\uc778 \uc989\uc2a8, \uc18c\ucf13\uc774 \uc0ac\uc6a9\ud558\ub294 \uc790\uc6d0\uc744 \ub418\ub3c4\ub85d \ub2a6\uac8c \ubc18\ud658\ud55c\ub2e4\ub294 \uac83\uc785\ub2c8\ub2e4. ephemeral port\ub97c \ud3ec\ud568\ud574\uc11c\uc694.<\/span><\/p>\n\n<\/span>
    \ud2b9\ud788, \ud074\ub77c\uc774\uc5b8\ud2b8 \uc18c\ucf13\uc5d0\uc11c close() \uc2dc\uc2a4\ud15c \ucf5c\ub85c \uba3c\uc800 \uc18c\ucf13\uc744 \ub2eb\ub294 \uacbd\uc6b0 \uc18c\ucf13\uc740 TIME_WAIT \uc0c1\ud0dc\uc5d0 \uba38\ubb34\ub974\uac8c \ub429\ub2c8\ub2e4.<\/span>
    \uc774 \ub3d9\uc548 \uc774 \uc18c\ucf13\uc5d0 \ud560\ub2f9\ub418\uc5b4 \uc788\ub294 ephemeral port\ub294 \uc0ac\uc6a9\ub420 \uc218 \uc5c6\uace0 \uadf8\ub9cc\ud07c \ub3d9\uc2dc\uc5d0 \uac00\uc9c8 \uc218 \uc788\ub294 \ud074\ub77c\uc774\uc5b8\ud2b8 \uc18c\ucf13 \uc218\ub294 \uc81c\ud55c\ub418\uaca0\uc8e0.<\/span><\/p>\n\n<\/span>

    <\/p>\n\n<\/span>
    \ubaa9\ucc28 - 3\ud3b8<\/span><\/h2>
    5. TIME_WAIT socket\n    5.1 TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc774 \ubb34\uc5c7\uc77c\uae4c\uc694?\n    5.2 TIME_WAIT socket buckets\n    5.3 TIME_WAIT socket reuse (TW_REUSE)\n    5.4 TCP timestamp\n    5.5 TIME_WAIT socket recycling (TW_RECYCLE)\n    5.6 Socket linger option\n6. \uacb0\ub860\n7. \ub9fa\uc73c\uba70\n8. FAQ\n<\/span><\/code><\/pre>
    5. TIME_WAIT socket<\/span><\/h2>
    \uc55e\uc11c \ub9d0\uc500\ub4dc\ub9b0 \ub300\ub85c, TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc740 \uac00\uc6a9\ud55c local port \uc218\ub97c \uacbd\uac10\uc2dc\ucf1c \ub3d9\uc2dc\uc5d0 \uac00\uc9c8 \uc218 \uc788\ub294 \ud074\ub77c\uc774\uc5b8\ud2b8 \uc18c\ucf13 \uc218\ub97c \uc81c\uc57d\ud569\ub2c8\ub2e4.<\/span>
    \ubcf8 \uc7a5\uc5d0\uc11c\ub294 \uc774\ub7ec\ud55c TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc5d0 \ub300\ud574 \uc774\uc57c\uae30\ud558\ub3c4\ub85d \ud558\uaca0\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    5.1 TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc774 \ubb34\uc5c7\uc77c\uae4c\uc694?<\/span><\/h3>
    \uadf8\ub807\ub2e4\uba74, \uc815\ud655\ud788 TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc740 \uc5b8\uc81c \ubc1c\uc0dd\ud560\uae4c\uc694?<\/span>
    \uba3c\uc800, TCP \uc18c\ucf13 \uc0c1\ud0dc \uc804\uc774\ub3c4\ub97c \uc0b4\ud3b4\ubd05\uc2dc\ub2e4. \uc544\ub798 \uadf8\ub9bc\uc740 \uc704\ud0a4\ud53c\ub514\uc544\uc5d0\uc11c \ucc3e\uc544 \ubcfc \uc218 \uc788\ub294 TCP \uc18c\ucea3 \uc0c1\ud0dc \uc804\uc774\ub3c4\uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \"img2.png\"\n<\/span><\/p>\n\n<\/span>

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

    <\/span><\/div>
    <\/p>\n\n<\/span>
    \uc704 \uadf8\ub9bc\uc5d0\uc11c \uc54c \uc218 \uc788\ub4ef\uc774, active closing \ud558\ub294 \uc18c\ucf13\uc758 \ub9c8\uc9c0\ub9c9 \uc885\ucc29\uc9c0\uac00 TIME_WAIT \uc0c1\ud0dc\uc785\ub2c8\ub2e4.<\/span>
    \ubc14\uafb8\uc5b4 \ub9d0\ud558\uba74, \ud074\ub77c\uc774\uc5b8\ud2b8 \uc18c\ucf13\uc774\ub4e0 \uc11c\ubc84 \uc18c\ucf13\uc774\ub4e0 close() \uc2dc\uc2a4\ud15c \ucf5c\uc744 \uba3c\uc800 \ud638\ucd9c\ud55c \ucabd(active closing)\uc774 \ucd5c\uc885\uc801\uc73c\ub85c \uac00\uac8c\ub429\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc774\ud6c4 TIME_WAIT \uc0c1\ud0dc\uc5d0\uc11c\ub294 RFC793\uc5d0 \uc815\uc758\ub300\ub85c\ub77c\uba74 2MSL(Maximum Segment Lifetime), \uc989 2\ubd84 \ub3d9\uc548 \ub300\uae30\ud558\uac8c \ub429\ub2c8\ub2e4.<\/span>
    \uadf8\ub7f0\ub370, \uc2e4\uc81c\ub85c \ub300\ubd80\ubd84\uc758 OS\uc5d0\uc11c\ub294 \ucd5c\uc801\ud654\ub97c \uc704\ud574 1\ubd84 \uc815\ub3c4\ub97c TIME_WAIT \uc0c1\ud0dc\uc5d0\uc11c \ub300\uae30\ud558\ub3c4\ub85d \uad6c\ud604\ub418\uc5b4 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    \ub9ac\ub205\uc2a4\ub3c4 \uc774 \uc2dc\uac04\uc744 1\ubd84\uc73c\ub85c \uaddc\uc815\ud558\uace0 \uc788\uace0, \ubcc0\uacbd\uc774 \ubd88\uac00\ub2a5\ud569\ub2c8\ub2e4. (\ucee4\ub110 \ucf54\ub4dc\uc5d0 \uc0c1\uc218\ub85c \uc815\ud574\uc838 \uc788\uc2b5\ub2c8\ub2e4.)<\/span><\/p>\n\n<\/span>
    \uc77c\ubd80 \uad6c\uae00\uc5d0\uc11c \ucc3e\uc544\ubcfc \uc218 \uc788\ub294 \ubb38\uc11c\uc5d0\ub294 '<\/span>net.ipv4.fin_timeout<\/span><\/code>'\uc744 \uc218\uc815\ud558\uba74, TIME_WAIT\uc5d0\uc11c \ub300\uae30\ud558\ub294 \uc2dc\uac04\uc744 \uc218\uc815 \uac00\ub2a5\ud558\ub2e4\uace0 \ub9d0\ud558\uace0 \uc788\ub294\ub370\uc694.<\/span>
    '<\/span>net.ipv4.fin_timeout<\/span><\/code>'\uc740 FIN_WAIT_2 \uc0c1\ud0dc\uc5d0 \uba38\ubb34\ub97c \uc218 \uc788\ub294 \ucd5c\ub300 \uc2dc\uac04\uc744 \uc124\uc815\ud569\ub2c8\ub2e4.<\/span>
    (RFC\uc5d0\uc11c\ub294 TIME_WAIT \uc0c1\ud0dc \uc678\uc5d0\ub294 \ubcc4\ub3c4 timeout\uc744 \uc815\uc758\ud558\uace0 \uc788\uc9c0 \uc54a\uc9c0\ub9cc, \ub300\ubd80\ubd84\uc758 \uc2dc\uc2a4\ud15c\uc5d0\uc11c\ub294 \ucd5c\uc801\ud654\ub97c \uc704\ud574 \ubcc4\ub3c4 timeout \uc2dc\uac04\uc744 \ub461\ub2c8\ub2e4.)<\/span>
    \uc2e4\uc81c \uc138\uacc4\uc5d0\uc11c FIN_WAIT_2\uc5d0 \uba38\ubb34\ub974\ub294 \uc18c\ucf13\uc740 \ub9e4\uc6b0 \ub4dc\ubb3c\uace0, \uc5b4\ucc28\ud53c \uc790\uc5f0\uc2a4\ub808 TIME_WAIT \uc0c1\ud0dc\ub85c \uc804\uc774\ub418\uae30\uc5d0 \uc774 \uc124\uc815\uac12\uc740 \uae30\ubcf8\uc73c\ub85c \ub450\uc5b4\ub3c4 \ud070 \ubb38\uc81c\uac00 \uc5c6\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \ud55c\uac00\uc9c0 \uac15\uc870\ud558\uace0 \uc2f6\uc740 \uac83\uc740, TIME_WAIT \uc0c1\ud0dc\ub294 '<\/span>\uc798\ubabb\ub41c<\/span><\/code>' \uc0c1\ud0dc\uac00 \uc544\ub2c8\ub77c\ub294 \uac83 \uc785\ub2c8\ub2e4.<\/span>
    \uc18c\ucf13\uc758 \uc9c0\uadf9\ud788 \uc815\uc0c1\uc801\uc778 \uc0dd\uba85 \uc8fc\uae30 \uc911 \ud55c \uc0c1\ud0dc\uc774\uba70, \uc18c\ucf13\uc758 gracefully shutdown\uc744 \ubcf4\uc7a5\ud558\ub294 \ubd88\uac00\uacb0\ud55c \uc694\uc18c\uc785\ub2c8\ub2e4.<\/span>
    \uadf8\ub9ac\uace0 \ub290\uc2a8\ud788 \uacb0\ud569\ub41c \ub124\ud2b8\uc6cc\ud06c \ud2b9\uc131\uc0c1 \uc18c\ucf13\uc740 \ub418\ub3c4\ub85d gracefully shutdown \ub418\uc5b4\uc57c \ub370\uc774\ud130\uc758 \uc720\uc2e4 \ub4f1\uc758 \ubb38\uc81c\uac00 \uc5c6\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uba3c\uc800, \uc6f9 \uc11c\ubc84\ub97c \uc608\ub85c \ub4e4\uc5b4 TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc744 \ud655\uc778\ud574 \ubcf4\ub3c4\ub85d \ud558\uaca0\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    HTTP keepalive \uc635\uc158\uc744 \uc0ac\uc6a9\ud558\uc9c0 \uc54a\ub294 \uc6f9\uc11c\ubc84\uac00 \uc788\ub2e4\uace0 \ud569\uc2dc\ub2e4.<\/span>
    \uc774 \uc11c\ubc84\uc5d0 \uac00\uc11c \ub2e4\uc74c\uacfc \uac19\uc740 \uba85\ub839\uc5b4\ub97c \uc0ac\uc6a9\ud558\uba74 \ud604\uc7ac TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc744 \ud655\uc778\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ netstat -n -t | grep 'TIME_WAIT'\nProto Recv-Q Send-Q Local Address           Foreign Address         State\ntcp6       0      0 10.77.57.106:10080      10.77.94.26:37901       TIME_WAIT  \ntcp6       0      0 10.77.57.106:10080      10.77.94.26:37900       TIME_WAIT  \ntcp6       0      0 10.77.57.106:10080      10.77.94.26:37905       TIME_WAIT  \ntcp6       0      0 10.77.57.106:10080      10.77.56.86:41811       TIME_WAIT  \ntcp6       0      0 10.77.57.106:10080      10.77.56.82:48168       TIME_WAIT\n<\/span><\/code><\/pre>
    \uc704 \uc608\uc81c\ub294 \uc11c\ubc84 \ud3ec\ud2b8 10080\uc744 \uc0ac\uc6a9\ud558\ub294 \uc6f9\uc11c\ubc84\uc5d0\uc11c \ubc1c\uc0dd\ud55c TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\ub4e4\uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    HTTP 1.1\uc5d0\uc11c\ub294 \uc2a4\ud399\uc0c1 \ub204\uac00 \uba3c\uc800 \uc18c\ucf13\uc744 \ub04a\uc744\uc9c0 \uc815\uc758\ud558\uace0 \uc788\uc9c0 \uc54a\uc2b5\ub2c8\ub2e4.<\/span>
    \ud558\uc9c0\ub9cc \uc77c\ubc18\uc801\uc778 \uad6c\ud604\uc5d0\uc11c keepalive \uc124\uc815\uc744 \uc0ac\uc6a9\ud558\uc9c0 \uc54a\ub294\ub2e4\uba74, \uc11c\ubc84\uc5d0\uc11c \ud074\ub77c\uc774\uc5b8\ud2b8\ub85c \ub370\uc774\ud130\ub97c \uc804\uc1a1 \ud6c4 \uc989\uc2dc close() \uc2dc\uc2a4\ud15c \ucf5c\uc744 \ubd88\ub7ec \uc5f0\uacb0\uc744 \ub04a\uc2b5\ub2c8\ub2e4.<\/span>
    \uadf8\ub798\uc11c \uc704 \uacbd\uc6b0\ucc98\ub7fc \uc11c\ubc84\uc5d0 TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc774 \ub0a8\uac8c \ub418\ub294 \uac83 \uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uadf8\ub807\ub2e4\uba74, \uc774 \uacbd\uc6b0(\uc11c\ubc84 \uc18c\ucf13\uc5d0\uc11c TIME_WAIT\uc774 \ubc1c\uc0dd\ud558\ub294 \uacbd\uc6b0) TIME_WAIT \uc18c\ucf13\uc774 \ub9ce\uc544\uc9c0\ub294 \uac83\uc774 \ubb38\uc81c\uac00 \ub420\uae4c\uc694?<\/span>
    \uacb0\ub860\ubd80\ud130 \ub9d0\ud558\uc790\uba74, \uc544\uc8fc \ud06c\uac8c\ub294 \ubb38\uc81c \ub418\uc9c0 \uc54a\ub294\ub2e4\ub294 \uac83 \uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    5.2 TIME_WAIT socket buckets<\/span><\/h3>
    \uba3c\uc800, \uc5b4\ub5a4 \uc2dc\uc2a4\ud15c\uc774 \uac00\uc9c8 \uc218 \uc788\ub294 TIME_WAIT \uc0c1\ud0dc \uc18c\ucf13 \uac1c\uc218 \uc81c\ud55c\uc744 \ud655\uc778\ud574 \ubd05\uc2dc\ub2e4.<\/span>
    '<\/span>net.ipv4.tcp_max_tw_buckets<\/span><\/code>' \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\uc5d0 \uc774 \uac12\uc774 \uc124\uc815\ub418\uc5b4 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    \ub2e4\uc74c\uacfc \uac19\uc740 \uba85\ub839\uc5b4\ub85c \uc774 \uc124\uc815\uac12\uc744 \ud655\uc778\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ sysctl net.ipv4.tcp_max_tw_buckets\nnet.ipv4.tcp_max_tw_buckets = 65536\n<\/span><\/code><\/pre>
    \uc774 \uc2dc\uc2a4\ud15c\uc5d0\uc11c TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc740 \ub3d9\uc2dc\uc5d0 65,536\uac1c \uc874\uc7ac\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    \uadf8\ub807\ub2e4\uba74, \ub9cc\uc57d TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13 \uac1c\uc218\uac00 \uc774\ubcf4\ub2e4 \ub9ce\uc544\uc9c0\uba74 \uc5b4\ub5bb\uac8c \ub420\uae4c\uc694? \uc11c\ubc84 \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc5d0 \ubb38\uc81c\uac00 \ubc1c\uc0dd\ud560\uae4c\uc694?<\/span><\/p>\n\n<\/span>
    TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc740 \uc704 \uc124\uc815\ub41c \uac12 \ubcf4\ub2e4 \ub9ce\uc544\uc9c8 \uc218 \uc5c6\uc2b5\ub2c8\ub2e4.<\/span>
    \uc774\ubbf8 \uc774 \uc124\uc815\uac12 \ub9cc\ud07c\uc758 TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc774 \uc788\ub2e4\uba74, TIME_WAIT \uc0c1\ud0dc\ub85c \uc804\uc774\ub418\uc5b4\uc57c \ud560 \uc18c\ucf13\uc740 \ub354\uc774\uc0c1 \ub300\uae30\ud558\uc9c0 \uc54a\uace0 \ud30c\uad34(destroy)\ub418\uc5b4 \ubc84\ub9bd\ub2c8\ub2e4.<\/span>
    \uc989, gracefully shutdown\ud558\uc9c0 \uc54a\uace0 \uacfc\uaca9\ud558\uac8c \ub2eb\ud600\ubc84\ub9ac\ub294 \uac83\uc774\uc9c0\uc694. \uadf8\ub9ac\uace0 \uc11c\ubc84 \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc740 \uc774\ub97c \uc54c\uc9c0 \ubabb\ud569\ub2c8\ub2e4.<\/span>
    \uc77c\ubc18\uc801\uc73c\ub85c \uc774\ub7f0 \uacbd\uc6b0, \uc18c\ucf13\uc740 \ud30c\uad34\ub418\uace0 '<\/span>\/var\/log\/messages<\/span><\/code>'\uc640 \uac19\uc740 \uacf3\uc5d0 \ub2e4\uc74c\uacfc \uac19\uc740 \ub85c\uadf8 \uba54\uc2dc\uc9c0\uac00 \ub0a8\uc744 \uac83\uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    TCP: time wait bucket table overflow\n<\/span><\/code><\/pre>
    \uc774\ub807\uac8c \ud30c\uad34\ub41c \uc18c\ucf13\uc740 TCP\uc758 gracefully shutdown \uc6d0\uce59\uc5d0 \ubc97\uc5b4\ub098\uc9c0\ub9cc, \uc11c\ubc84 \uc131\ub2a5\uc774\ub098 \uc218\uc6a9\ub7c9\uc5d0 \ud070 \uc601\ud5a5\uc744 \uc8fc\uc9c0 \uc54a\uc2b5\ub2c8\ub2e4.<\/span>
    \uadf8\ub7ec\ub098, \uc18c\ucf13\uc774 gracefully shutdown \ub418\uc9c0 \uc54a\uc73c\ubbc0\ub85c \uc11c\ubc84\uc5d0\uc11c \ud074\ub77c\uc774\uc5b8\ud2b8\ub85c \uc544\uc9c1 \ub0b4\ubcf4\ub0b4\uc9c0\uc9c0 \uc54a\ub294 \ub370\uc774\ud130\ub3c4 \uc989\uc2dc \uc0ac\ub77c\uc9c0\uac8c \ub429\ub2c8\ub2e4. \uc774 \uacbd\uc6b0, \ud074\ub77c\uc774\uc5b8\ud2b8\uc5d0\uc11c\ub294 \ubd88\uc644\uc804\ud55c \ub370\uc774\ud130\ub97c \uc218\uc2e0\ud558\uac8c \ub420 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \ub530\ub77c\uc11c, \ub418\ub3c4\ub85d \uc18c\ucf13\uc740 gracefully shutdown \ub418\uc5b4\uc57c \ud558\uba70, \uc694\uccad\ub7c9\uc774 \ub9ce\uc740 \uc11c\ubc84\uc758 \uacbd\uc6b0 \uc774 \uac12\uc744 \uc801\ub2f9\ud788 \ub192\uc5ec\ub450\ub294 \uac83\uc774 \uc88b\uc2b5\ub2c8\ub2e4.<\/span>
    \uc5ed\uc2dc \uba54\ubaa8\ub9ac\uc591\uc774 \uc8fc\uc694 trade-off \uc694\uc778\uc774\uae30\uc5d0, \uc0c1\ub300\uc801\uc73c\ub85c \uba54\ubaa8\ub9ac \uc591\uc774 \ucda9\ubd84\ud55c \uc11c\ubc84\ub77c\uba74 \uc801\ub2f9\ud788 \ub192\uc5ec\ub3c4 \ubb38\uc81c \ub418\uc9c0 \uc54a\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \ub2e4\uc74c\uacfc \uac19\uc740 \uba85\ub839\uc5b4\ub85c \uc801\ub2f9\ub7c9 \uc99d\uac00 \uc2dc\ud0b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ sysctl -w net.ipv4.tcp_max_tw_buckets=\"1800000\"\n<\/span><\/code><\/pre>
    \ub610 \ud55c\uac00\uc9c0 \uc758\ubb38\uc744 \uac00\uc838\ubcfc \uc218 \uc788\ub294\ub370, \uc5b4\ub5a4 \ud2b9\uc815 foreign address\uc640 foreign port\ub97c \uac00\uc9c0\ub294 \uc18c\ucf13\uc774 TIME_WAIT \uc0c1\ud0dc\uc5d0 \uc788\ub2e4\uace0 \ud560 \ub54c \ub611\uac19\uc740 \uc8fc\uc18c\uc640 \ud3ec\ud2b8\ub85c \ud074\ub77c\uc774\uc5b8\ud2b8\uc5d0\uc11c \uc5f0\uacb0 \uc694\uccad\uc774 \uc624\uba74 \uc5b4\ub5bb\uac8c \ub420\uae4c\uc694?<\/span><\/p>\n\n<\/span>
    RFC 1122\uc5d0\uc11c\ub294 \uac19\uc740 \uc8fc\uc18c\uc640 \uc8fc\uc18c\ub97c \uc0ac\uc6a9\ud558\ub294 TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc774 \uc788\ub354\ub77c\ub3c4, SYN\uc744 \ubc1b\uc73c\uba74 \uc774 \uc18c\ucf13\uc744 \uc7ac\uc0ac\uc6a9\ud558\ub3c4\ub85d \ub418\uc5b4 \uc788\uc2b5\ub2c8\ub2e4. \ub54c\ubb38\uc5d0, \ud2b9\ubcc4\ud55c \ub2e4\ub978 \uc124\uc815\uc774 \uc5c6\uc5b4\ub3c4 \ubb38\uc81c \ub420 \uac83\uc774 \uc5c6\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc815\ub9ac\ud558\uc790\uba74, \uc11c\ubc84 \uc18c\ucf13\ub9cc \uc788\ub294 \uc11c\ubc84\uc5d0\uc11c\ub294 TIME_WAIT \uc18c\ucf13\uc774 \ub9ce\uc544\uc9c0\ub354\ub77c\ub3c4 \uc131\ub2a5 \ubc0f \uc218\uc6a9\ub7c9 \uce21\uba74\uc5d0\uc11c\ub294 \ubb38\uc81c\uac00 \uc5c6\uc2b5\ub2c8\ub2e4.<\/span>
    \uc774\ub7ec\ud55c \uc720\ud615\uc758 \uc11c\ubc84\uc778 \uacbd\uc6b0, TIME_WAIT \uc18c\ucf13 \uc218\uc5d0 \ud06c\uac8c \ubbfc\uac10\ud560 \ud544\uc694\uac00 \uc5c6\uc2b5\ub2c8\ub2e4.<\/span>
    \ub2e4\ub9cc, TCP \uc18c\ucf13\uc740 \ub418\ub3c4\ub85d gracefully shutdown \ub418\uc5b4\uc57c \ud558\ubbc0\ub85c '<\/span>net.ipv4.tcp_max_tw_buckets<\/span><\/code>' \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\ub97c \uc801\ub2f9\ud788 \uc0c1\ud5a5\ud560 \uc218 \uc788\uaca0\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    5.3 TIME_WAIT socket reuse (TW_REUSE)<\/span><\/h3>
    \uadf8\ub7f0\ub370, \ub300\uaddc\ubaa8 \uc11c\ube44\uc2a4\uc5d0\uc11c\ub294 \uc6f9\uc11c\ubc84\ub77c\uace0 \ud560\uc9c0\ub77c\ub3c4 \ub2e4\ub978 \uc11c\ubc84\uc5d0 \uc9c8\uc758\ud558\ub294 \uacbd\uc6b0\uac00 \uc788\uc2b5\ub2c8\ub2e4. \uc774 \uacbd\uc6b0, \uc11c\ubc84\ub294 \ub610 \ub2e4\ub978 \uc11c\ubc84\uc758 \ud074\ub77c\uc774\uc5b8\ud2b8\uac00 \ub418\ub294 \uac83\uc774\uc9c0\uc694.<\/span>
    \uc774\ub7f4\ub54c\ub294 TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13 \uac1c\uc218\uac00 \uc131\ub2a5\uc5d0 \uc601\ud5a5\uc744 \ubbf8\uce60 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc5b4\ub5a4 \uc11c\ubc84\uac00 \ub2e4\ub978 \uc11c\ubc84\ub85c \uc9c8\uc758\ud558\ub294\ub370, \ubcc4\ub3c4\uc758 connection pool\uc744 \ub450\uc9c0 \uc54a\uace0 HTTP RESTful API\ub85c \uc9c8\uc758\ud55c\ub2e4\uace0 \uac00\uc815\ud569\uc2dc\ub2e4.<\/span>
    \uadf8\ub9ac\uace0 \uc774\ub54c HTTP keepalive\ub97c \uc0ac\uc6a9\ud558\uc9c0 \uc54a\ub294\ub2e4\uace0 \uac00\uc815\ud569\uc2dc\ub2e4.<\/span>
    \uac00\uc815\ud55c\ub2e4\uace0 \ud588\uc9c0\ub9cc, \uad49\uc7a5\ud788 \uc77c\ubc18\uc801\uc73c\ub85c \uc0ac\uc6a9\ub418\ub294 \ud615\ud0dc\uc77c \uac83 \uc785\ub2c8\ub2e4. \uc77c\ubc18\uc801\uc73c\ub85c TCP keepalive\uc758 \uacbd\uc6b0 L4 \uc2a4\uc704\uce58\uc5d0 \uc758\ud574 \ubb34\uc6a9\uc9c0\ubb3c\uc774 \ub418\uae30\uc5d0 \ub300\uac1c\ub294 \uc0ac\uc6a9\ud558\uc9c0 \uc54a\uae30 \ub54c\ubb38\uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc774 \ub54c TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13 \uc218\uac00 local port\ub97c \uc120\uc810\ud558\uc5ec \uc0dd\uc131\ud560 \uc218 \uc788\ub294 \ud074\ub77c\uc774\uc5b8\ud2b8 \uc18c\ucf13 \uac1c\uc218\ub97c \uc81c\ud55c\uc2dc\ud0a4\uba70, \uc774\ub294 \ub2e4\uc2dc \ub9d0\ud574 \ub2e4\ub978 \uc11c\ubc84\uc5d0 \ub3d9\uc2dc \uc9c8\uc758\ud560 \uc218 \uc788\ub294 \uc5f0\uacb0 \uc218\ub97c \uc904\uc785\ub2c8\ub2e4. \ucd5c\uc545\uc758 \uacbd\uc6b0 \ub2e4\ub978 \uc11c\ubc84\ub85c 1\ubd84\ub0b4 \uc9c8\uc758 \uc218\uac00 \uac00\uc9c8 \uc218 \uc788\ub294 ephemeral port \uc218\ubcf4\ub2e4 \ub9ce\uc73c\uba74, HTTP \uc5f0\uacb0 \uc2dc\uc810\uc5d0 \uc694\uccad\uc740 \uc2e4\ud328\ud560 \uac83\uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uadf8\ub7fc \uc774\ub7ec\ud55c \uacbd\uc6b0 \uc5b4\ub5bb\uac8c \ud574\uc57c \ud560\uae4c\uc694? \uadf8\ub9ac\uace0 \uc774\ubbf8 \ud544\uc694 \uc5c6\ub294 \uc18c\ucf13\uc744 \ub2eb\uc558\uc744 \ubfd0\uc778\ub370, \uc774 \ub54c\ubb38\uc5d0 \uc0c8\ub85c\uc6b4 \uc18c\ucf13\uc744 \ub9cc\ub4e4\uc9c0 \ubabb\ud558\ub294 \uac83\uc774 \ud569\ub2f9\ud560\uae4c\uc694?<\/span>
    \uc774\ub97c \ud574\uc18c\ud558\uae30 \uc704\ud55c \ubc29\ubc95\uc73c\ub85c\ub294 \ud06c\uac8c \ub124\uac00\uc9c0 \uc815\ub3c4\uac00 \uc788\uc744 \uac83 \uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    (1) \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc5d0\uc11c connection pool\uc744 \uc0ac\uc6a9<\/span><\/strong>
    \uc131\ub2a5\uacfc \uc720\uc5f0\uc131\uba74\uc5d0\uc11c \uac00\uc7a5 \ucd94\ucc9c\ud558\ub294 \ubc29\ubc95\uc774\uc9c0\ub9cc, \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc744 \uace0\uccd0\uc57c \ud569\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    (2) TW_REUSE \uc635\uc158\uc744 \uc0ac\uc6a9<\/span><\/strong>
    \uc0ac\uc6a9\ud560 \uc218 \uc788\ub294 local port \uc218\uac00 \ubaa8\uc790\ub77c\uba74, \ud604\uc7ac TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13 \uc911 \ud504\ub85c\ud1a0\ucf5c\uc0c1 \uc0ac\uc6a9\ud574\ub3c4 \ubb34\ubc29\ud574 \ubcf4\uc774\ub294 \uc18c\ucf13\uc744 \uc7ac\uc0ac\uc6a9\ud569\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    (3) TW_RECYCLE \uc635\uc158\uc744 \uc0ac\uc6a9<\/span><\/strong>
    TIME_WAIT \uc0c1\ud0dc\uc5d0 \uba38\ubb34\ub974\ub294 \uc2dc\uac04\uc744 \ubcc0\uacbd\ud558\uc5ec TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13 \uc218\ub97c \uc904\uc785\ub2c8\ub2e4. 1\ubd84 \ub300\uc2e0 RTO(Retransmission Timeout) \uc2dc\uac04\ub9cc\ud07c\uc73c> \ub85c TIME_WAIT \uc0c1\ud0dc\uc5d0 \uba38\ubb34\ub974\ub294 \uc2dc\uac04\uc774 \uacbd\uac10\ub418\ub294\ub370, \ub9ac\ub205\uc2a4\uc5d0\uc11c\ub294 200ms\uae4c\uc9c0 \uc774 \uc2dc\uac04\uc774 \uc904 \uc218 \uc788\uc2b5\ub2c8\ub2e4. (\ucd5c\uc18c RTO\uac00 200ms)<\/span><\/p>\n\n<\/span>
    (4) Socket linger \uc635\uc158\uc744 \uad49\uc7a5\ud788 \uc9e7\uc740 \uc2dc\uac04\uc744 \ub9e4\uac1c\ubcc0\uc218\ub85c \uc8fc\uc5b4 \uc0ac\uc6a9<\/span><\/strong>
    FIN \ub300\uc2e0 RST\ub97c \ubcf4\ub0b4\uac8c \uc720\ub3c4\ud558\uba70, \uc774 \ub54c \uc18c\ucf13\uc744 \ud30c\uad34\ud558\uc5ec \uc18c\ucf13\uc774 TIME_WAIT \uc0c1\ud0dc\uc5d0 \uba38\ubb34\ub974\uc9c0 \uc54a\uac8c \ud569\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    TW_RECYCLE, socket linger \uc635\uc158\uc740 TW_REUSE \ubcf4\ub2e4\ub294 \uc0c1\ub300\uc801\uc73c\ub85c \uacfc\uaca9\ud55c \ubc29\ubc95\uc774\uba70 \ub418\ub3c4\ub85d \uad8c\uc7a5\ud558\uc9c0 \uc54a\uc2b5\ub2c8\ub2e4. \uad00\ub828\ub41c \ub0b4\uc6a9\uc740 \uc774\ud6c4 \ubcc4\ub3c4\uc758 \uc808\uc5d0\uc11c \uc11c\uc220\ud558\uaca0\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    TW_REUSE\ub97c \uc0ac\uc6a9\ud558\ub824\uba74 '<\/span>net.ipv4.tcp_tw_reuse<\/span><\/code>' \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\ub97c \uc124\uc815\ud574\uc57c \ud569\ub2c8\ub2e4.<\/span>
    \uadf8\ub7f0\ub370, \uc704\uc5d0\uc11c \uc18c\uac1c\ud55c \ub300\ub85c TW_REUSE\ub294 \ud2b9\uc815 \uc0c1\ud669\uc5d0\uc11c\ub9cc TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc744 \uc7ac\uc0ac\uc6a9\ud558\uac8c \ub418\ub294\ub370\uc694. \uc774 \ud310\ub2e8 \ub85c\uc9c1\uc5d0\uc11c\ub294 TCP timestamp\ub77c\ub294 \ud655\uc7a5 \uc635\uc158\uc744 \uc0ac\uc6a9\ud569\ub2c8\ub2e4. \ub54c\ubb38\uc5d0, TW_REUSE \uc635\uc158\uc744 \ud65c\uc131\ud654 \ud558\ub824\uba74 \uba3c\uc800 TCP timestamp \uc635\uc158\ub3c4 \ud65c\uc131\ud654 \ub418\uc5b4\uc57c \ud569\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    TCP timestamp\uac00 \uc0ac\uc6a9\ub418\uba74 TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc5d0 \ud1b5\uc2e0\uc774 \uc774\ub8e8\uc5b4\uc9c4 \ub9c8\uc9c0\ub9c9 \uc2dc\uac04(timestamp)\ub97c \uae30\ub85d\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    TW_REUSE \uc635\uc158\uc744 \ud65c\uc131\ud654 \ud55c \uc0c1\ud0dc\uc5d0\uc11c \ud074\ub77c\uc774\uc5b8\ud2b8 \uc18c\ucf13 \uc0dd\uc131\uc2dc, TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13 \uc911 \ud604\uc7ac timestamp \ubcf4\ub2e4 \ud655\uc2e4\ud788 \uc791\uc740 \uac12\uc758 timestamp\ub97c \uac00\uc9c0\ub294 \uc18c\ucf13\uc740 \uc7ac\uc0ac\uc6a9(reuse) \ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    \uc77c\ubc18\uc801\uc73c\ub85c \ub9ac\ub205\uc2a4\uc5d0\uc11c timestamp\uc758 \ub2e8\uc704\ub294 \ucd08 \uc774\ubbc0\ub85c, TIME_WAIT \uc0c1\ud0dc\ub85c \uc804\uc774\ub41c\uc9c0 1\ucd08 \uc774\ud6c4\uc758 \uc18c\ucf13\ub4e4\uc740 \uc7ac\uc0ac\uc6a9 \ud560 \uc218 \uc788\uac8c \ub429\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \ub2e4\uc74c\uacfc \uac19\uc740 \uba85\ub839\uc5b4\ub85c TW_REUSE \uc635\uc158\uc744 \ud65c\uc131\ud654 \ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ sysctl -w ipv4.tcp_timestamps=\"1\"\n$ sysctl -w net.ipv4.tcp_tw_reuse=\"1\"\n<\/span><\/code><\/pre>
    \ud55c\uac00\uc9c0 \uc720\uc758\ud560 \uc810\uc740, TW_REUSE \uc635\uc158\uc740 \ud1b5\uc2e0\uc744 \ud558\ub294 \uc591\uce21 \ubaa8\ub450 TCP timestamp \uc635\uc158\uc774 \uc124\uc815\ub418\uc5b4 \uc788\uc5b4\uc57c \ud65c\uc131\ud654\ub41c\ub2e4\ub294 \uac83 \uc785\ub2c8\ub2e4.<\/span>
    \ud55c\ucabd\uc5d0 TCP timestamp \uc635\uc158\uc774 \ud65c\uc131\ud654 \ub418\uc9c0 \uc54a\uc740 \uacbd\uc6b0, TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc744 \uc7ac\uc0ac\uc6a9 \ud560 \uc218 \uc5c6\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    5.4 TCP timestamp<\/span><\/h3>
    TCP\uc5d0\uc11c\ub294 sequence number\ub85c \ud328\ud0b7\uc758 \uc21c\uc11c(ordering)\uc744 \ud310\ubcc4\ud569\ub2c8\ub2e4. \uc774 \uac12\uc740 32\ube44\ud2b8 unsigned int \ud615\uc73c\ub85c 0\uc5d0\uc11c \uc57d 40\uc5b5\uae4c\uc9c0\uc758 \ud45c\ud604\ubc94\uc704\ub97c \uac00\uc9c0\uace0<\/span>
    \uadf8\ub7f0\ub370, \ub9e4\uc6b0 \ube60\ub978 \ub124\ud2b8\uc6cc\ud06c \ud658\uacbd\uc774 \uc788\ub2e4\uace0 \uac00\uc815\ud574 \ubd05\uc2dc\ub2e4. \uadf8\ub9ac\uace0 \ubd88\ud589\ud788\ub3c4 receiver\ub294 \uc774 \ub124\ud2b8\uc6cc\ud06c\ubcf4\ub2e4\ub294 \uc870\uae08 \ub290\ub9b0 \ucc98\ub9ac \uc18d\ub3c4\ub97c \uac00\uc9c0\uace0 \uc788\ub2e4\uace0 \uac00\uc815\ud574 \ubd05\uc2dc\ub2e4.<\/span>
    \uc774\ub7f0 \uc0c1\ud669\uc5d0\uc11c sequence number\ub294 \uc911\ucca9(wrapping) \ub420 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc608\ub97c \ub4e4\uc790\uba74, \uc5b4\ub290 \uc21c\uac04 receiver\ub294 \uc5b4\ub290 sender\ub85c\ubd80\ud130 100\uc774\ub77c\ub294 sequence number\ub97c \uac00\uc9c4 \ud328\ud0b7\uc744 \ubc1b\uc558\ub2e4\uace0 \ud569\uc2dc\ub2e4.<\/span>
    \uc774\ud6c4 receiver\ub294 100 \uc774\uc0c1\uc758 sequence number\ub97c \uac00\uc9c0\ub294 \ud328\ud0b7\ub4e4\uc744 \uae30\ub300\ud569\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc774\ud6c4 receiver\ub294 \uc21c\uc2dd\uac04\uc5d0 40\uc5b5\uac1c \uc774\uc0c1\uc758 \ud328\ud0b7\uc774 \uc218\uc2e0 \ub418\uc5c8\ub2e4\uace0 \ud569\uc2dc\ub2e4. \uadf8\ub7f0\ub370 \uc544\uc9c1 receiver\ub294 \uc774 \ud328\ud0b7\ub4e4\uc744 \uae4c\ubcf4\uc9c0 \uc54a\uc558\uc2b5\ub2c8\ub2e4.<\/span>
    NIC, \uc989 \ub124\ud2b8\uc6cc\ud06c \uc5b4\ub311\ud130\uc5d0 \uc758\ud574 \uc218\uc2e0\ub418\uc5c8\uc73c\ub098 \uc544\uc9c1 \ucee4\ub110\uc758 TCP stack\uc5d0\uc11c\ub294 \uc774 \ud328\ud0b7\uc744 \uc5f4\uc5b4\ubcf4\uc9c0 \uc54a\uc740 \uc0c1\ud0dc\uc785\ub2c8\ub2e4. (10G\uc758 \ub124\ud2b8\uc6cc\ud06c\ub77c\uba74 \ubd88\uac00\ub2a5\ud55c \uc77c\uc774 \uc544\ub2d9\ub2c8\ub2e4.)<\/span>
    \uc774 \ub54c \ub9c8\uc9c0\ub9c9\ucbe4 \uc218\uc2e0\ub41c \ud328\ud0b7\uc758 sequence number\ub294 unsigned int \ud615\uc758 \ud45c\ud604 \ubc94\uc704 \ub54c\ubb38\uc5d0 \ud544\uc2dc overflow \ub418\uc5c8\uc744 \uac83\uc785\ub2c8\ub2e4.<\/span>
    \ud3b8\uc758\uc0c1 TCP stack\uc774 \uae4c\ubd10\uc57c\ud560 \ud328\ud0b7\uc758 sequence number\uac00 101~4,294,967,296\uae4c\uc9c0, \uadf8\ub9ac\uace0 \uc774\ud6c4 overflow\ub418\uc5b4\uc11c 0~200 \uc774\ub77c\uace0 \uac00\uc815\ud569\uc2dc\ub2e4.<\/span><\/p>\n\n<\/span>
    receiver\ub294 100 \uc774\uc0c1\uc758 sequence number\ub97c \uae30\ub300\ud558\uace0 \uc788\uc5c8\ub294\ub370, \uc774\ubcf4\ub2e4 \uc791\uc740 \uc218\uc778 0~100\uc758 sequence number\ub97c \ubc1b\uc740 \uc0c1\ud669\uc774 \ub429\ub2c8\ub2e4.<\/span>
    \uc989 \uc21c\uc11c(ordering)\uc5d0 \uc704\ubc30\ub418\ubbc0\ub85c \uc774 \ud328\ud0b7\ub4e4\uc740 \uc0c8\ub85c \uc218\uc2e0\ub41c \ud328\ud0b7\uc784\uc5d0\ub3c4 \ubd88\uad6c\ud558\uace0 \uc870\uc6a9\ud788 \ubc84\ub824\uc9d1\ub2c8\ub2e4. (silently dropped)<\/span><\/p>\n\n<\/span>
    \ub610, \uc774 \uacbd\uc6b0 \uc911\ubcf5\ub41c sequence number\uc758 \ud328\ud0b7\ub3c4 \uc874\uc7ac\ud558\uac8c \ub418\ub294\ub370\uc694. \uc608\ucee8\ub300 sequence number\uac00 101\uc778 \ud328\ud0b7\uc774 \ub450 \uac1c \uc874\uc7ac\ud569\ub2c8\ub2e4.<\/span>
    \ub124\ud2b8\uc6cc\ud06c \uc0c1 \ud328\ud0b7\uc740 reordering\ub420 \uc218 \uc788\uc74c\uc744 \uac10\uc548\ud55c\ub2e4\uba74, \uc774 \ub450 \uac1c\uc758 \ud328\ud0b7\uc758 \uc120\ud6c4 \uad00\uacc4\ub97c \ud655\uc815 \uc9c0\uc744 \uc218 \uc788\uc744\uae4c\uc694?<\/span><\/p>\n\n<\/span>
    \ub2f9\uc5f0\ud788 \ud655\uc815\ud560 \uc218 \uc5c6\uc2b5\ub2c8\ub2e4. TCP stack\uc758 \uad6c\ud604\uc5d0 \ub530\ub77c \ub2e4\ub974\uaca0\uc9c0\ub9cc, \ub458 \uc911 \uc5b4\ub290 \ud55c \ud328\ud0b7\uc740 \ubc84\ub824\uc9c8 \uac83\uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc774\ub7ec\ud55c \ubb38\uc81c, \uc989 wrapped sequence number \ubb38\uc81c\ub97c \ud574\uacb0\ud558\uae30 \uc704\ud574, RFC 1323\uc5d0\uc11c\ub294 PAWS(Protection against Wrapped Sequence Numbers)\ub77c\ub294 \ubc29\ubc95\uc744 \uc81c\uc548\ud569\ub2c8\ub2e4.<\/span>
    \uc774\ub294 reordering\uc744 \ud310\ubcc4\ud558\ub294 \uc694\uc18c\uc5d0 sequence number \ubfd0\ub9cc \uc544\ub2c8\ub77c timestamp \uac12\uc744 \uc0ac\uc6a9\ud558\uaca0\ub2e4\ub294 \uac83\uc785\ub2c8\ub2e4.<\/span>
    PAWS\uac00 \uad6c\ud604\ub41c TCP stack\uc740 timestamp\uac00 \ud3ec\ud568\ub41c \uc5b4\ub290 \ud328\ud0b7\uc744 \ubc1b\uc558\uc744 \ub54c \uc774 timestamp\ub97c \uae30\ub85d\ud574\ub450\uba70 connection \ubcc4\ub85c \uad00\ub9ac\ud569\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc774\ub984\uc5d0\uc11c \uc720\ucd94\ud560 \uc218 \uc788\ub4ef\uc774 timestamp\ub294 \ub2e8\ubc29\ud5a5\uc73c\ub85c \uc99d\uac00\ub418\ub294 \uc5b4\ub290 \uac12\uc785\ub2c8\ub2e4. \uc77c\ubc18\uc801\uc73c\ub85c timestamp\ub294 \ubc00\ub9ac\ucd08(millisecond) \ub2e8\uc704\ub85c system clock\uc5d0\uc11c \uac00\uc838\ub2e4 \uc4f0\ub294 \uacbd\uc6b0\uac00 \ub9ce\uc2b5\ub2c8\ub2e4.<\/span>
    \uc5ec\uae30\uc11c \ud55c\uac00\uc9c0 \uc0dd\uac01\ud574 \ubcfc\ub9cc\ud55c \uac83\uc774 \uc788\ub294\ub370\uc694. \uadf8\ub7fc sender\uc640 receiver\uac04 \ud1b5\uc2e0\uc5d0\uc11c \uc774 timestamp \uac12\uc774 \ub3d9\uae30\ud654(synchronization)\ub418\uc5b4 \uc788\uc5b4\uc57c \ud560\uae4c\uc694?<\/span><\/p>\n\n<\/span>
    \uacb0\ub860\ubd80\ud130 \uc774\uc57c\uae30 \ud558\uc790\uba74 \uadf8\ub7f4 \ud544\uc694\uac00 \uc5c6\uc2b5\ub2c8\ub2e4. \uc0ac\uc2e4 timestamp\ub294 \ub2e8\ubc29\ud5a5\uc73c\ub85c \uc99d\uac00\ud558\ub294 \uc5b4\ub290 \uac12\uc774\uba74 \ub418\uba70 system clock\uacfc \uc5f0\ub3d9\ub420 \ud544\uc694\uac00 \uc5c6\uc2b5\ub2c8\ub2e4. \ub17c\ub9ac\uc801\uc73c\ub85c\ub294 sequence number\uc758 high order\ub85c\uc11c \uc0ac\uc6a9\ub418\uae30 \ub54c\ubb38\uc785\ub2c8\ub2e4.<\/span><\/strong><\/p>\n\n<\/span>
    timestamp\ub97c \ub454\ub2e4\uba74, \uc704\uc640 \uac19\uc740 \uc608\uc81c(\ub2e8\uc2dc\uac04\uc5d0 sequence number\uac00 overflow\ub418\ub294 \uc0c1\ud669)\uc5d0\uc11c \uc0c8\ub85c \uc218\uc2e0\ud55c \ud328\ud0b7\uc744 \ubc84\ub9ac\ub294 \ubb38\uc81c\ub97c \ud574\uacb0 \ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    sequence number\uac00 \uc911\ucca9(wrap)\ub418\uc5c8\ub354\ub77c\ub3c4 timestamp\ub294 \ub354 \ub192\uc740 \uac12\uc774\uae30\uc5d0 \uc0c8\ub85c \uc218\uc2e0\ub41c \ud328\ud0b7\uc774\ub77c\uace0 \uc778\uc9c0\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    (\uc704\uc5d0\uc11c \uc5b8\uae09\ud55c\ub300\ub85c sequence number\uc758 high order\ub77c \uc0dd\uac01\ud558\uba74 \uc27d\uac8c \uc774\ud574\ub420 \uac83 \uac19\uc2b5\ub2c8\ub2e4.)<\/span><\/p>\n\n<\/span>
    \ub9ac\ub205\uc2a4\uc5d0\uc11c TCP timestamp\ub97c \uc0ac\uc6a9\ud558\uae30 \uc704\ud574\uc11c\ub294 '<\/span>net.ipv4.tcp_timestamps<\/span><\/code>'\ub77c\ub294 \ucee4\ub110 \ud30c\ub77c\ubbf8\ud130\ub97c 1\ub85c \uc124\uc815\ud574\uc57c \ud569\ub2c8\ub2e4.<\/span>
    \ud604\uc7ac \uc124\uc815\uac12\uc744 \ud655\uc778\ud558\ub824\uba74 \ub2e4\uc74c\uacfc \uac19\uc740 \uba85\ub839\uc5b4\ub97c \uc0ac\uc6a9\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ sysctl net.ipv4.tcp_timestamps\n<\/span><\/code><\/pre>
    \ucd5c\uc2e0\uc758 \uc77c\ubc18\uc801\uc778 \ub9ac\ub205\uc2a4 \ubc30\ud3ec\ud310\uc5d0\uc11c\ub294 \uae30\ubcf8\uac12\uc73c\ub85c \ud65c\uc131\ud654\ub418\uc5b4 \uc788\uc2b5\ub2c8\ub2e4.<\/span>
    \ucc38\uace0\ub85c, \uc62c\ubc14\ub974\uac8c \ub3d9\uc791\ud558\ub824\uba74 sender\/receiver \ubaa8\ub450 \ud65c\uc131\ud654 \uc0c1\ud0dc\uc774\uc5b4\uc57c \ud569\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    5.5 TIME_WAIT socket recycling (TW_RECYCLE)<\/span><\/h3>
    TW_REUSE \uc635\uc158\ubcf4\ub2e4 \uacfc\uaca9\ud55c \ubc29\ubc95\uc740 TW_RECYCLE \uc635\uc158\uc744 \uc0ac\uc6a9\ud558\ub294 \uac83\uc785\ub2c8\ub2e4.<\/span>
    TW_RECYCLE\uc740 \uc18c\ucf13\uc774 TIME_WAIT \uc0c1\ud0dc\uc5d0 \uba38\ubb34\ub974\ub294 \uc2dc\uac04\uc744 RTO \ub9cc\ud07c \uc7ac\uc815\uc758\ud558\uac8c \ub418\ub294\ub370\uc694.<\/span>
    RTO \uc2dc\uac04\uc740 RTT\uc5d0 \uc601\ud5a5\uc744 \ubc1b\uc73c\uba70, \uc77c\ubc18\uc801\uc73c\ub85c 1\ubd84 \ubcf4\ub2e4\ub294 \uc9e7\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \ub2e4\uc74c\uacfc \uac19\uc740 \uba85\ub839\uc5b4\ub85c TW_RECYCLE \uc635\uc158\uc744 \ud65c\uc131\ud654 \ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    $ sysctl -w ipv4.tcp_timestamps=\"1\"\n$ sysctl -w net.ipv4.tcp_tw_reuse=\"1\"\n$ sysctl -w net.ipv4.tcp_tw_recycle=\"1\"\n<\/span><\/code><\/pre>
    TW_RECYCLE \uc635\uc158\uc744 \ud65c\uc131\ud654\ud558\ub824\uba74, \uba3c\uc800 TCP timestamp\uc640 TW_REUSE\ub97c \ud65c\uc131\ud654\uc2dc\ucf1c\uc57c \ud558\ub294 \uac83\uc5d0 \uc720\uc758\ud574\uc57c \ud569\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uadf8\ub7f0\ub370, TW_RECYCLE\uc740 \ud06c\uac8c \uad8c\uc7a5\ud558\uc9c0 \uc54a\uc2b5\ub2c8\ub2e4.<\/span>
    \ud074\ub77c\uc774\uc5b8\ud2b8\uac00 NAT \ud658\uacbd\uc778 \uacbd\uc6b0 \uc77c\ubd80 \ud074\ub77c\uc774\uc5b8\ud2b8\ub85c \ubd80\ud130\uc758 SYN \ud328\ud0b7\uc774 \uc720\uc2e4\ub420 \uc218 \uc788\uae30 \ub54c\ubb38\uc785\ub2c8\ub2e4.<\/span>
    \uc989, TW_RECYCLE \uc0ac\uc6a9\uc2dc \uc77c\ubd80 TCP \uc5f0\uacb0 \uc694\uccad\uc740 \uc2e4\ud328\ud558\uac8c \ub429\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc65c \uc774\ub7f0 \ud604\uc0c1\uc774 \ubc1c\uc0dd\ud560\uae4c\uc694?<\/span><\/p>\n\n<\/span>
    TW_RECYCLE \uc0ac\uc6a9\uc2dc, TIME_WAIT \uc0c1\ud0dc\ub85c \ub300\uae30\ud558\ub294 \uc2dc\uac04\uc774 \uadf9\ud788 \uc9e7\uc544\uc838 TIME_WAIT\uc5d0 \ub0a8\uc544 \uc788\ub294 \uc18c\ucf13\uc774 \uac70\uc758 \uc5c6\ub2e4\uace0 \ud574\ub3c4 \ub420 \uac83 \uc785\ub2c8\ub2e4. (\ubb3c\ub860 peer\uac00 timestamp\ub97c \uc0ac\uc6a9\ud558\uc9c0 \uc54a\ub294\ub2e4\uba74 \ub0a8\uc544\uc788\uc2b5\ub2c8\ub2e4.) \uadf8\ub807\uc9c0\ub9cc, \ucee4\ub110\uc740 \ub418\ub3c4\ub85d TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc774 \uc788\ub294 \uac83\ucc98\ub7fc \ud589\ub3d9\ud574\uc57c \ud558\ub824 \ud569\ub2c8\ub2e4. \uc18c\ucf13\uc758 gracefully shutdown\uc744 \ubcf4\uc7a5\ud558\uae30 \uc704\ud574\uc11c\uc8e0.<\/span><\/p>\n\n<\/span>
    \uc608\ub97c \ub4e4\uc5b4, \uc5b4\ub5a4 \uc18c\ucf13\uc774 \uc788\uace0 active closing \ub418\uc5c8\ub2e4\uace0 \ud569\uc2dc\ub2e4. TIME_WAIT \uc0c1\ud0dc\uc5d0\uc11c \ub9e4\uc6b0 \uc9e7\uc740 \uc2dc\uac04 \uba38\ubb34\ub978 \ud6c4 \uc0ad\uc81c\ub420 \uac83 \uc785\ub2c8\ub2e4. \uc774\uc73d\uace0 \uac19\uc740 foreign address \/ port\ub85c \ubd80\ud130 \uc5f0\uacb0 \uc694\uccad\uc774 \uc640\uc11c \uc0c8\ub85c\uc6b4 \uc5f0\uacb0\uc774 \ub9fa\uc5b4\uc84c\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc774\ub54c sequence number\uac00 \uc5ed\uc804\ub41c \ud328\ud0b7\uc774 \ub3c4\ucc29\ud588\ub2e4\uace0 \ud569\uc2dc\ub2e4.<\/span>
    \uadf8\ub7f0\ub370, \uc774 \ud328\ud0b7\uc774 \uc774\uc804\uc5d0 \uc5f0\uacb0\uc774 \ub04a\uc5b4\uc9c4 \uc18c\ucf13\uc5d0 \ub300\ud55c \ud328\ud0b7\uc778\uc9c0, \uc9c0\uae08 \uc5f0\uacb0\uc774 \ub9fa\uc5b4\uc9c4 \uc18c\ucf13\uc5d0 \ub300\ud55c \ud328\ud0b7\uc778\uc9c0 \uc54c \uc218 \uc788\uc744\uae4c\uc694? \uc774\ub7f0 \uacbd\uc6b0\uc5d0 \uc5b4\ub5bb\uac8c \ud574\uc57c \ud560\uae4c\uc694?<\/span><\/p>\n\n<\/span>
    \uc774\ub7ec\ud55c \ubb38\uc81c\uc810\uc744 \ud574\uacb0\ud558\uae30 \uc704\ud574 TW_RECYCLE \uc635\uc158\uc744 \uc0ac\uc6a9\ud558\uba74 TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc774 \uc788\ub294 \uac83\ucc98\ub7fc \uba87\uac00\uc9c0 \ubaa8\uc0ac\ub97c \ud558\uac8c \ub429\ub2c8\ub2e4. \uc774\ub7ec\ud55c \ub85c\uc9c1\uc744 \uac04\ub2e8\ud788 \uc11c\uc220\ud558\uba74 \uc544\ub798\uc640 \uac19\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    (1) TIME_WAIT \uc0c1\ud0dc\ub85c \ub4e4\uc5b4\uac00\uba74, \ub2e4\ub978 \uad6c\uc870\uccb4\uc5d0 \ud604\uc7ac \uc18c\ucf13\uc758 foreign address\uc640 timestamp \uac12\uc744 \uae30\ub85d\ud569\ub2c8\ub2e4.<\/span><\/strong>
    (2) \ud574\ub2f9 foreign address\/port\uc758 \ud328\ud0b7\uc774 \uc624\uba74, (1) \uacfc\uc815\uc5d0\uc11c \uc54c\uace0 \uc788\ub294 timestamp\uc640 \ub300\uc870\ud558\uc5ec \uc774\ubcf4\ub2e4 \uc791\uc740 timestamp\ub77c\uba74 \uc870\uc6a9\ud788 \ubc84\ub824\ubc84\ub9bd\ub2c8\ub2e4.<\/span><\/strong>
    (3) \uc774 \uad6c\uc870\uccb4\uc5d0 \uc800\uc7a5\ub41c \uac12\uc740 \uc6d0\ub798 TIME_WAIT \uc0c1\ud0dc\ub85c \uccb4\ub958\ud558\ub294 \uc2dc\uac04 \ub9cc\ud07c(\uc989 1\ubd84) \uc720\uc9c0\ub429\ub2c8\ub2e4.<\/span><\/strong><\/p>\n\n<\/span>
    \uc989, timestamp\uac00 \uc5ed\uc804\ub41c \ud328\ud0b7\uc740 \ubc84\ub9bd\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uadf8\ub7f0\ub370, \uc704\uc5d0\uc11c \uc124\uba85\ud55c\ub300\ub85c timestamp\ub294 peer \ubcc4\ub85c \ub3d9\uae30\ud654\ub418\uc5b4 \uc788\uc9c0 \uc54a\uc2b5\ub2c8\ub2e4. NAT\ub97c \uc0ac\uc6a9\ud558\ub294 \ud074\ub77c\uc774\uc5b8\ud2b8\ub4e4\uc740 \uc11c\ubc84 \uc785\uc7a5\uc5d0\uc11c\ub294 \ubaa8\ub450 \uac19\uc740 \uc8fc\uc18c\ub97c \uc0ac\uc6a9\ud558\ub294 \uac83\ucc98\ub7fc \ubcf4\uc77c \uac83\uc785\ub2c8\ub2e4. \uadf8\ub7f0\ub370, \ubcf4\ub0b4\ub294 \ud328\ud0b7\uc758 timestamp\ub294 \uac01 \ud074\ub77c\uc774\uc5b8\ud2b8 \ubcc4\ub85c \ub2e4\ub978 \uac12\uc744 \uac00\uc9c8 \uc218 \uc788\uc2b5\ub2c8\ub2e4. \ub54c\ubb38\uc5d0 \uae30\uc874 \uc18c\ucf13\uc774 \ub9c8\uc9c0\ub9c9\uc73c\ub85c \uae30\ub85d\ud55c \ud328\ud0b7\uc758 timestamp \uac12\uc774 \uc0c8\ub85c\uc774 \uc18c\ucf13 \uc5f0\uacb0\uc744 \uc694\uccad\ud558\ub294 SYN \ud328\ud0b7\uc5d0 \ud3ec\ud568\ub41c timestamp \ubcf4\ub2e4 \ud074 \uc218 \uc788\uc2b5\ub2c8\ub2e4. \uadf8\ub9ac\uace0 \uc774 \uacbd\uc6b0, \uc704\uc5d0\uc11c \uc11c\uc220\ud55c\ub300\ub85c \uc870\uc6a9\ud788 \ubc84\ub824\uc9c0\uac8c \ub420 \uac83 \uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \ud2b9\ud788, front-end \uc11c\ubc84\uc5d0\uc11c\ub294 TW_RECYCLE \uc635\uc158\uc744 (\uc808\ub300) \uc0ac\uc6a9\ud558\uba74 \uc548\ub418\ub294\ub370, \uc774 \uc11c\ubc84\ub294 \uc8fc\ub85c \uc778\ud130\ub137\uc5d0\uc11c \uc218\uc2e0\ub418\ub294 \ud074\ub77c\uc774\uc5b8\ud2b8\uc758 \uc694\uccad\uc744 \ubc1b\uac8c\ub420 \uac83\uc774\uae30 \ub54c\ubb38\uc785\ub2c8\ub2e4.<\/span>
    \uc778\ud130\ub137\uc758 \ud074\ub77c\uc774\uc5b8\ud2b8\ub4e4\uc740 NAT \ud658\uacbd\uc77c \ud655\ub960\uc774 \ud07d\ub2c8\ub2e4. 3G\/LTE \ub4f1\uc758 \ubaa8\ubc14\uc77c \ub124\ud2b8\uc6cc\ud06c \ud658\uacbd\uc740 \uc77c\uc885\uc758 \uac70\ub300\ud55c NAT \ud658\uacbd\uc774\uace0\uc694, \uc911\uad6d\uacfc \uac19\uc774 IP\uac00 \ubaa8\uc790\ub77c\ub294 \ud658\uacbd\uc778 \uacbd\uc6b0 NAT\ub97c \ub9ce\uc774 \uc0ac\uc6a9 \ud560 \uac83 \uc785\ub2c8\ub2e4. \uc774\ub7f0 \uacbd\uc6b0, \ub9ce\uc740 \uc218\uc758 \ud074\ub77c\uc774\uc5b8\ud2b8\uc5d0\uc11c \uc11c\ubc84\ub85c \uc811\uc18d \ubabb\ud558\ub294 \uc7a5\uc560\uac00 \ubc1c\uc0dd\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    5.6 Socket linger option<\/span><\/h3>
    TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc744 \uc904\uc774\ub294 \ub610 \ud558\ub098\uc758 \"<\/span>\uadf9\ub2e8\uc801<\/span><\/code>\" \ubc29\ubc95\uc740, \uadf9\ud788 \uc9e7\uc740 \uc2dc\uac04(\uadf9\ub2e8\uc801\uc73c\ub85c 0\ucd08)\uc73c\ub85c linger \uc635\uc158\uc744 \ud65c\uc131\ud654\ud558\ub294 \uac83 \uc785\ub2c8\ub2e4.<\/span>
    \uc18c\ucf13\ub2f9 \uc124\uc815\ud560 \uc218 \uc788\ub294 \uc635\uc158\uc778\ub370, \uae30\ubcf8 \uc124\uc815\uc740 \ube44\ud65c\uc131\ud654\uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc6d0\ub798 TCP \uc18c\ucf13\uc740 close() \ud638\ucd9c\ud558\ub294 \uac70\uc758 \uc989\uc2dc \ubc18\ud658\ub429\ub2c8\ub2e4. \uadf8\ub9ac\uace0 \uc18c\ucf13\uc744 \ub2eb\uae30 \uc704\ud55c \uc2e4\uc81c \ub3d9\uc791(\uc544\uc9c1 \uc18c\ucf13 \ubc84\ud37c\uc5d0 \ub0a8\uc544 \uc788\ub294 \ub370\uc774\ud130\ub97c \ubcf4\ub0b8\ub2e4\ub358\uac00, FIN\/ACK\ub97c \ubcf4\ub0b8\ub2e4\ub358\uac00)\uc740 \ucee4\ub110\uc5d0 \uc758\ud558\uc5ec \uc9c4\ud589 \ub418\uc8e0. \uc774 \uc18c\ucf13\uc740 \uacb0\uad6d TIME_WAIT \uc0c1\ud0dc\uac00 \ub418\uc5b4 \uc8fc\uc5b4\uc9c4 \uc2dc\uac04(\ub9ac\ub205\uc2a4\uc5d0\uc11c\ub294 1\ubd84) \ub300\uae30\ud558\uac8c \ub429\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    linger \uc635\uc158\uc740 close()\uc758 \ubc18\ud658\uc744 \uc989\uac01\uc801\uc73c\ub85c \ud558\uc9c0 \uc54a\uace0, \uc989 non-blocking\uc73c\ub85c \ubc18\ud658\ub418\uc9c0 \uc54a\uace0 blocking manner\ub85c \ucc98\ub9ac\ud558\uaca0\ub2e4\ub294 \uac83\uc744 \uc758\ubbf8\ud569\ub2c8\ub2e4. \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc740 close()\uc2dc linger \uc635\uc158 \ud65c\uc131\ud654\uc2dc \uc8fc\uc5b4\uc9c4 \ub9e4\uac1c\ubcc0\uc218 \uc2dc\uac04\uae4c\uc9c0 block \ub429\ub2c8\ub2e4. \uc774 \uc2dc\uac04 \ub3d9\uc548 \ucee4\ub110\uc740 \uc18c\ucf13 \ubc84\ud37c\uc5d0 \ub0a8\uc544 \uc788\ub294 \ub370\uc774\ud130\ub4e4\uc744 \ub0b4\ubcf4\ub0b4\ub824 \ub178\ub825\ud569\ub2c8\ub2e4. \uadf8\ub9ac\uace0 \uc8fc\uc5b4\uc9c4 \uc2dc\uac04\uc548\uc5d0 \uc774\ub7ec\ud55c \ucc98\ub9ac\uac00 \uc644\ub8cc\ub418\uba74, \uc989 \uc815\uc0c1 \ucc98\ub9ac\ub418\uba74 \uc77c\ubc18\uc801\uc778 \ubc29\ubc95\uacfc \ub611\uac19\uc774 \ucee4\ub110\uc740 FIN\uc744 \ubcf4\ub0b4\uace0 \uc18c\ucf13\ub3c4 \uacb0\uad6d TIME_WAIT \uc0c1\ud0dc\uac00 \ub418\uc8e0. \uadf8\ub7ec\ub098 \uc8fc\uc5b4\uc9c4 \uc2dc\uac04\ub0b4 \uc815\uc0c1 \ucc98\ub9ac\ub418\uc9c0 \ubabb\ud558\uba74, \ucee4\ub110\uc740 FIN \ub300\uc2e0 RST\uc744 \ubcf4\ub0b4\uace0 \uc989\uc2dc \uc18c\ucf13\uc740 \ud30c\uad34\ub429\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc744 \uc904\uc774\ub294 \uadf9\ub2e8\uc801\uc778 \ubc29\ubc95\uc740, \uc774 linger \uc635\uc158\uc5d0\uc11c\uc758 block \ub420 \uc218 \uc788\ub294 \uc2dc\uac04\uc744 '0'\uc73c\ub85c \uc124\uc815\ud558\ub294 \uac83 \uc785\ub2c8\ub2e4. \uadf8\ub7ec\uba74, close()\uc2dc \ucee4\ub110\uc740 \ud55c\uc21c\uac04\ub3c4 \uae30\ub2e4\ub9ac\uc9c0 \uc54a\uace0 FIN \ub300\uc2e0 RST\ub97c \ubcf4\ub0b4\uba70 \uc18c\ucf13\uc744 \ud30c\uad34\ud560 \uac83\uc785\ub2c8\ub2e4. \ub54c\ubb38\uc5d0 TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\ub3c4 \ub0a8\uc544\uc788\uc9c0 \uc54a\ub294 \uac83\uc774\uc8e0.<\/span><\/p>\n\n<\/span>
    \uadf8\ub7ec\ub098, linger \uc635\uc158\uc740 \uacb0\ucf54 TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc744 \uc81c\uac70\ud558\uae30 \uc704\ud55c \uc635\uc158\uc774 \uc544\ub2d9\ub2c8\ub2e4. \ub370\uc774\ud130\ub97c peer\uc5d0\uac8c \uc644\uc804\ud788 \uc804\ub2ec(delivery)\ud558\uae30 \uc704\ud574 \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc5d0 \ubcf4\ub2e4 \ud1b5\uc81c\uad8c\uc744 \uc8fc\ub294 \ud558\ub098\uc758 \uc635\uc158\uc77c \ubfd0\uc774\uc8e0. \uc77c\ubc18\uc801\uc778 \ucc98\ub9ac\uc5d0\uc11c \uc18c\ucf13\uc740 \ucee4\ub110\uc5d0 \uc758\ud574 gracefully shutdown\ud558\ub294 \uac83\uc774 \uc62c\ubc14\ub985\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc774\ub807\uac8c\uae4c\uc9c0 \ud558\ub294 \uc800\ubcc0\uc5d0\ub294 TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc744 \ud574\uc545\uc73c\ub85c \ubcf4\uae30 \ub54c\ubb38\uc778 \uac83 \uac19\uc2b5\ub2c8\ub2e4.<\/span>
    \uadf8\ub7ec\ub098 \ud328\ud0b7\uc758 reordering\uc774\ub098 \uc720\uc2e4\uc774 \uc788\uc744 \uc218 \uc788\ub294 \ub124\ud2b8\uc6cc\ud06c\uc758 \ud2b9\uc131\uc0c1, \uc18c\ucf13\uc740 \ub418\ub3c4\ub85d gracefully shutdown \ub418\uc5b4\uc57c \ud569\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    \uc774\ubc88\uc7a5\uc5d0\uc11c \ubc18\ubcf5\ud574\uc11c \ub9d0\uc500\ub4dc\ub9ac\ub294 \uac74, TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13\uc740 \ud06c\ub098\ud070 \ud574\uc545\uc774 \uc544\ub2c8\ub77c\ub294 \uac83\uc785\ub2c8\ub2e4. \uc18c\ucf13\uc774 \uc815\uc0c1 \uc885\ub8cc\ub418\ub294 \uacfc\uc815\uc778 \uac83\uc774\uc9c0\uc694.<\/span>
    \uc11c\ubc84 \uc18c\ucf13\uc5d0\uc11c\ub294 \uc77c\ubc18\uc801\uc73c\ub85c \uc544\ubb34\ub7f0 \ubb38\uc81c\uac00 \uc5c6\uc73c\uba70, \ud074\ub77c\uc774\uc5b8\ud2b8 \uc18c\ucf13\uc774\ub77c\ub3c4 TW_REUSE \uc635\uc158\uc73c\ub85c \uadf9\ubcf5\uc774 \uac00\ub2a5\ud569\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    TW_REUSE \uc635\uc158\uc774 \uc0ac\uc6a9 \ubd88\uac00\ub2a5\ud55c \uadf9\ud788 \uc608\uc678\uc801\uc778 \uc0c1\ud669(\uc608\ub97c \ub4e4\uc5b4, timestamp\ub97c \uc0ac\uc6a9\ud558\uc9c0 \uc54a\ub294 \ub2e4\uc218\uc758 \uc11c\ubc84\uc640 \ud1b5\uc2e0)\uc5d0\uc11c\ub77c\ub3c4 TW_RECYCLE, linger \uc635\uc158 \uac19\uc740 \uadf9\ub2e8\uc801\uc778 \ucc98\uce58\ub294 \uc9c0\uc591\ud574\uc57c \ud560 \uac83 \uc785\ub2c8\ub2e4. \uc774\ub7ec\ud55c \uacbd\uc6b0\uc5d0 \uc815\ub9d0\ub85c TIME_WAIT \uc0c1\ud0dc\uc758 \uc18c\ucf13 \uac1c\uc218\uac00 \uc131\ub2a5\uc758 \ubcd1\ubaa9\uc810\uc774\ub77c\uba74, keepalive\ub97c \uc0ac\uc6a9\ud558\uac70\ub098, connection pool \ub4f1\uc744 \uad6c\ud604\ud558\ub294 \ub4f1 \uc560\ud50c\ub9ac\ucf00\uc774\uc158 \uc790\uccb4\ub97c \uace0\uccd0\uc57c \ud560 \uac83 \uc785\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>
    6. \uacb0\ub860<\/span><\/h2>
    \uc0dd\uac01\ubcf4\ub2e4 \uaf64 \uae34 \uae00\uc774 \ub418\uc5c8\ub294\ub370, \uc801\ub2f9\ud788 \uc694\uc57d\ud558\uc790\uba74 \ub2e4\uc74c\uacfc \uac19\uc2b5\ub2c8\ub2e4.<\/span><\/p>\n\n<\/span>