{"id":429,"date":"2010-02-28T21:34:34","date_gmt":"2010-02-28T20:34:34","guid":{"rendered":"http:\/\/ccievoice.ksiazek.be\/?p=429"},"modified":"2025-01-11T18:28:05","modified_gmt":"2025-01-11T17:28:05","slug":"ecn-configuration","status":"publish","type":"post","link":"https:\/\/collaboration.ksiazek.be\/?p=429","title":{"rendered":"ECN Configuration"},"content":{"rendered":"<p>WRED discards packets and that is one way for the router to indicate a congestion. Routers will be now able to indicate a congestion condition by signaling it with an approach called Explicit Congestion Notification (ECN).<\/p>\n<p>ECN uses the two last bits in the TOS to indicate whether a device is ECN capable , and if so, whether congestion is experienced.<\/p>\n<blockquote>\n<ul>\n<li>If\u00a0the bit combination is 00 , then the router\u00a0means that\u00a0it is not ECN capable .<\/li>\n<li>If the bit combination is 01 or 10 , then the router means that\u00a0it is ECN capable and is not experiencing congestion<\/li>\n<li>If the bit combination is 11 , then the router means that it is ECN capable and is currently experiencing congestion<\/li>\n<\/ul>\n<\/blockquote>\n<p>The 7th bit is the ECT bit and the 8th bit is the CE bit.<\/p>\n<p>Cisco routers can use ECN as an extension to WRED and mark packets that exceed a specified value , instead of dropping the packets. So if the queue depth is at or below the WRED minimum threshold, the packets are sent normally,\u00a0 just as with WRED.<\/p>\n<p>Also if the queue depth is above the WRED maximum threshold, all packets are dropped , just as with WRED.<\/p>\n<p>But if the queue depth is currently in the range between the minimum and the maximum threshold, one of the following action can happen:<\/p>\n<blockquote>\n<ul>\n<li>If both endpoints are ECN capable , ECT and CE bits are set to 1 and sent to the destination, indicating that the transmission rate should be reduced.<\/li>\n<li>If neither endpoints support ECN, the normal WRED behaviour occurs.<\/li>\n<li>A packet with its ECN and CE bits marked can reach a destination router that has already a full queue. In such an instance, the notification is dropped.<\/li>\n<\/ul>\n<\/blockquote>\n<p>To activate ECN , use the following command under the policy-map : <span style=\"color: #ff0000;\">random-detect ecn<\/span> ( so it is applied under the MQC but you can apply it also under the interface)<\/p>\n","protected":false},"excerpt":{"rendered":"<p>WRED discards packets and that is one way for the router to indicate a congestion. Routers will be now able to indicate a congestion condition by signaling it with an approach called Explicit Congestion Notification (ECN). ECN uses the two last bits in the TOS to indicate whether a device is ECN capable , and [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[30,1,33],"tags":[59,137,81,136],"class_list":["post-429","post","type-post","status-publish","format-standard","hentry","category-ios","category-non-classe","category-written-theory","tag-ccie-voice-written","tag-ecn","tag-qos","tag-wred"],"_links":{"self":[{"href":"https:\/\/collaboration.ksiazek.be\/index.php?rest_route=\/wp\/v2\/posts\/429","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/collaboration.ksiazek.be\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/collaboration.ksiazek.be\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/collaboration.ksiazek.be\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/collaboration.ksiazek.be\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=429"}],"version-history":[{"count":1,"href":"https:\/\/collaboration.ksiazek.be\/index.php?rest_route=\/wp\/v2\/posts\/429\/revisions"}],"predecessor-version":[{"id":4455,"href":"https:\/\/collaboration.ksiazek.be\/index.php?rest_route=\/wp\/v2\/posts\/429\/revisions\/4455"}],"wp:attachment":[{"href":"https:\/\/collaboration.ksiazek.be\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=429"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/collaboration.ksiazek.be\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=429"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/collaboration.ksiazek.be\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=429"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}