{"id":5351,"date":"2011-07-22T16:32:07","date_gmt":"2011-07-22T16:32:07","guid":{"rendered":"http:\/\/www.beautifulwork.org\/?p=5351"},"modified":"2011-07-22T16:32:07","modified_gmt":"2011-07-22T16:32:07","slug":"parameter-tcp_retries1","status":"publish","type":"post","link":"https:\/\/www.trueangle.org\/index.php\/2011\/07\/22\/parameter-tcp_retries1\/","title":{"rendered":"parameter tcp_retries1"},"content":{"rendered":"<h5><u> A UNIX Parameter <\/u><\/h5>\n<pre>\n$cat \/proc\/sys\/net\/ipv4\/tcp_retries1\n3\n$echo 4 &gt; \/proc\/sys\/net\/ipv4\/tcp_r\n\n<\/pre>\n<p><\/p>\n<h5><u> Parameter Definition <\/u><\/h5>\n<pre>\nThis value influences the  time, after which TCP decides,\nthat  something  is   wrong  due  to  unacknowledged  RTO\nretransmissions,  and  reports   this  suspicion  to  the\nnetwork   layer.   RFC   1122  recommends   at   least  3\nretransmissions, which is the default.\n\n<\/pre>\n<p><\/p>\n<h5><u> Parameter Code Internals <\/u><\/h5>\n<p><code><br \/>\n<b> snippet 1 <\/b><br \/>\n{<br \/>\n                .procname       = \"tcp_retries1\",<br \/>\n                .data           = &amp;sysctl_tcp_retries1,<br \/>\n                .maxlen         = sizeof(int),<br \/>\n                .mode           = 0644,<br \/>\n                .proc_handler   = proc_dointvec_minmax,<br \/>\n                .extra2         = &amp;tcp_retr1_max<br \/>\n        },<\/p>\n<p><b> snippet 2 <\/b><br \/>\nif (retransmits_timed_out(sk, sysctl_tcp_retries1, 0, 0)) {<br \/>\n                        \/* Black hole detection *\/<br \/>\n                        tcp_mtu_probing(icsk, sk);<\/p>\n<p>                        dst_negative_advice(sk);<br \/>\n                }<\/p>\n<p><\/code><br \/>\n<\/p>\n<h5><u> Related From Research Paper <\/u><\/h5>\n<pre>\n<blockquote>\nIn  this paper  we have  investigated TCP  behavior  in a\n802.11b  wireless  Infrastructure  network  by  means  of\nexperiments  in  a  wireless  network  testbed.  We  have\ncompared results  obtained with similar  experiments done\nin  NS2  simulator. We  conclude  that  TCP ACK  skipping\nindeed  improves TCP  performance  in real-life  wireless\nLANs.  Although  the original  goal  was  to explore  the\nsimultaneous-send problem reported  in [1], several other\ninsights were  also obtained. The  NS2 simulations showed\nthe simultaneous-send  problem manifest when  MAC retries\nwere disabled. However we were unable to reproduce the NO\nMAC retries  case. Unlike  in the NS2  simulator, various\nstatus   indicators    cannot   be   tracked    in   real\nexperimentation. Instead the simultaneous-send phenomenon\nwas observed using standalone network sniffers.\n\n<\/blockquote>\n\nsource:\n\nExperimental Evaluation of the TCP Simultaneous-Send\nProblem in 802.11 Wireless Local Area Networks\nSumathi Gopal\nWINLAB, Rutgers University\n73, Brett Road\nPiscataway, NJ 08854-8048\n001 609 720 1202\nsumathi@winlab.rutgers.edu\nDipankar Raychaudhuri\nWINLAB, Rutgers University\n73, Brett Road\nPiscataway, NJ 08854-8048\n001 732 445 0877\nray@winlab.rutgers.edu\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>A UNIX Parameter $cat \/proc\/sys\/net\/ipv4\/tcp_retries1 3 $echo 4 &gt; \/proc\/sys\/net\/ipv4\/tcp_r Parameter Definition This value influences the time, after which TCP decides, that something is wrong due to unacknowledged RTO retransmissions, and reports this suspicion to the network layer. RFC 1122 recommends at least 3 retransmissions, which is the default. Parameter Code Internals snippet 1 { &hellip; <\/p>\n<p class=\"link-more\"><a href=\"https:\/\/www.trueangle.org\/index.php\/2011\/07\/22\/parameter-tcp_retries1\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;parameter tcp_retries1&#8221;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[1379,1387,1398,1548],"_links":{"self":[{"href":"https:\/\/www.trueangle.org\/index.php\/wp-json\/wp\/v2\/posts\/5351"}],"collection":[{"href":"https:\/\/www.trueangle.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.trueangle.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.trueangle.org\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.trueangle.org\/index.php\/wp-json\/wp\/v2\/comments?post=5351"}],"version-history":[{"count":0,"href":"https:\/\/www.trueangle.org\/index.php\/wp-json\/wp\/v2\/posts\/5351\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.trueangle.org\/index.php\/wp-json\/wp\/v2\/media?parent=5351"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.trueangle.org\/index.php\/wp-json\/wp\/v2\/categories?post=5351"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.trueangle.org\/index.php\/wp-json\/wp\/v2\/tags?post=5351"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}