{"id":84,"date":"2017-09-13T21:00:40","date_gmt":"2017-09-13T19:00:40","guid":{"rendered":"http:\/\/www.quisted.net\/?p=84"},"modified":"2017-09-13T21:00:40","modified_gmt":"2017-09-13T19:00:40","slug":"ospf-neighbor-states","status":"publish","type":"post","link":"https:\/\/www.quisted.net\/index.php\/2017\/09\/13\/ospf-neighbor-states\/","title":{"rendered":"OSPF Neighbor States"},"content":{"rendered":"<p>8 OSPF neighbor states:<\/p>\n<p><em><strong><span style=\"color: #ff0000;\">DOWN, ATTEMPT, INIT, 2WAY<\/span>, <span style=\"color: #339966;\">ExStart, Exchange, Loading, FULL<\/span><\/strong><\/em><\/p>\n<p><!--more--><\/p>\n<ul>\n<li><strong>DOWN<\/strong>\n<ul>\n<li>\u00a0via syslog message only<\/li>\n<\/ul>\n<\/li>\n<li><strong>ATTEMPT<\/strong>\n<ul>\n<li>via <em>sh ip ospf neighbor<\/em><\/li>\n<li>only with staticly defined neighbors<\/li>\n<li>May indicate layer 2 problem<\/li>\n<\/ul>\n<\/li>\n<li><strong>INIT<\/strong>\n<ul>\n<li>Received HELLO packet from neighbor<\/li>\n<li>compares names from other neighbors, <strong>doesn&#8217;t<\/strong> recognize you<\/li>\n<\/ul>\n<\/li>\n<li><strong>2WAY<\/strong>\n<ul>\n<li>Received HELLO packet from neighbor<\/li>\n<li>compares names from other neighbors, <strong>does<\/strong> recognize you<\/li>\n<\/ul>\n<\/li>\n<li><span style=\"color: #3366ff;\">(LSA&#8217;s ARE SEND FROM HERE)<\/span><\/li>\n<\/ul>\n<p><strong>WITHOUT DR<\/strong><\/p>\n<ul>\n<li><strong>ExStart <\/strong>(without DR)\n<ul>\n<li>ExStart starts when the first database descriptor (DD) message is received (syncs databases).<\/li>\n<li>Only sends LSA headers (only router ID).<\/li>\n<li>Election is held for master and slave router. Master in charge of inital sequence number.<\/li>\n<li>Router with higher RID is elected as master.<\/li>\n<\/ul>\n<\/li>\n<li><strong>Exchange<\/strong> (without DR)\n<ul>\n<li>Send to multicast <strong>224.0.0.5<\/strong><\/li>\n<li>Goes into Exchange after master\/slave election<\/li>\n<li>Multicast database descriptors (DD) packets untill they have the same LSID collectively for that area<\/li>\n<\/ul>\n<\/li>\n<li><strong>Loading (without DR)<\/strong>\n<ul>\n<li>When routers have the same LSID move into loading.<\/li>\n<li>For any missing LSA the router who is missing the LSA sends a Link State Request (LSR).<\/li>\n<li>The router listening to LSR sends a Link State Update (LSU).<\/li>\n<li>Router also sends ack message -&gt; LSAck or ack by sending same LSA back.<\/li>\n<\/ul>\n<\/li>\n<li><strong>FULL<\/strong>\n<ul>\n<li>When all LSAs have been send\/received\/ack move into FULL<\/li>\n<li>Fully Adjacent<\/li>\n<li>Database is fully populated<\/li>\n<li>Routers run the SPF to calculate the best path<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p><strong>WITH DR<\/strong><\/p>\n<p>With DR\/BDR on the segment, all other routers exchange databases with DR and BDR only.<br \/>\nOther router states are only in <strong>2way<\/strong> state.<\/p>\n<ul>\n<li><strong>Exchange with DR<\/strong>\n<ul>\n<li>Routers send messages to DR\/BDR on <strong>224.0.0.6<\/strong><\/li>\n<li>BR\/BDR send messages to routers on <strong>224.0.0.5<\/strong><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>8 OSPF neighbor states: DOWN, ATTEMPT, INIT, 2WAY, ExStart, Exchange, Loading, FULL<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0,"footnotes":""},"categories":[14,8],"tags":[],"class_list":["post-84","post","type-post","status-publish","format-standard","hentry","category-ospf","category-route"],"_links":{"self":[{"href":"https:\/\/www.quisted.net\/index.php\/wp-json\/wp\/v2\/posts\/84","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.quisted.net\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.quisted.net\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.quisted.net\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.quisted.net\/index.php\/wp-json\/wp\/v2\/comments?post=84"}],"version-history":[{"count":0,"href":"https:\/\/www.quisted.net\/index.php\/wp-json\/wp\/v2\/posts\/84\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.quisted.net\/index.php\/wp-json\/wp\/v2\/media?parent=84"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.quisted.net\/index.php\/wp-json\/wp\/v2\/categories?post=84"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.quisted.net\/index.php\/wp-json\/wp\/v2\/tags?post=84"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}