{"id":2062,"date":"2019-07-10T15:13:40","date_gmt":"2019-07-10T15:13:40","guid":{"rendered":"http:\/\/wiki.thomasandsofia.com\/?p=2062"},"modified":"2020-05-08T09:55:56","modified_gmt":"2020-05-08T09:55:56","slug":"section-9-osi-layer-2-data-link-layer","status":"publish","type":"post","link":"https:\/\/wiki.thomasandsofia.com\/?p=2062","title":{"rendered":"Section 9: OSI Layer 2 &#8211; Data Link Layer"},"content":{"rendered":"<p><a href=\"http:\/\/wiki.thomasandsofia.com\/?p=2039\">&lt; Section 8<\/a> | <a href=\"\/course-introduction\/\">Home<\/a> | <a href=\"http:\/\/wiki.thomasandsofia.com\/?p=2067\">Section 10 &gt;<\/a><\/p>\n<p>26% Completed<\/p>\n<h1>53: Introduction<\/h1>\n<p><a href=\"https:\/\/www.udemy.com\/cisco-icnd1\/learn\/lecture\/8601360#content\" target=\"_blank\" rel=\"noopener\">https:\/\/www.udemy.com\/cisco-icnd1\/learn\/lecture\/8601360#content<\/a><\/p>\n<h1>54: Local Are Network Layer 2 &#8211; Ethernet<\/h1>\n<p><a href=\"https:\/\/www.udemy.com\/cisco-icnd1\/learn\/lecture\/8601364#content\" target=\"_blank\" rel=\"noopener\">https:\/\/www.udemy.com\/cisco-icnd1\/learn\/lecture\/8601364#content<\/a><\/p>\n<ul>\n<li>Frames are encoded and decoded into bits at Layer 2<\/li>\n<li>Error detection and correction for the physical layer can be provided here.<\/li>\n<li>Ethernet is the Layer 2 medium used on Local Area Networks<\/li>\n<li><a href=\"https:\/\/en.wikipedia.org\/wiki\/List_of_network_protocols_(OSI_model)\">https:\/\/en.wikipedia.org\/wiki\/List_of_network_protocols_(OSI_model)<\/a><\/li>\n<\/ul>\n<h2>OSI Reference Model &#8211; Encapsulation<\/h2>\n<ul>\n<li>Layer 7 (Application): Data<\/li>\n<li>Layer 6 (Presentation)<\/li>\n<li>Layer 5 (Session)<\/li>\n<li>Layer 4 (Transport): Segment<\/li>\n<li>Layer 3 (Network): Packet<\/li>\n<li>Layer 2 (Data-Link): Frame<\/li>\n<li>Layer 1 (Physical)<\/li>\n<\/ul>\n<h2>The Ethernet Header<\/h2>\n<ul>\n<li>Preamble: 8 Bytes\n<ul>\n<li>Used to help the sender and receiver synchronize<\/li>\n<\/ul>\n<\/li>\n<li>Destination and Source Addresses: 6 Bytes each\n<ul>\n<li>MAC addresses<\/li>\n<\/ul>\n<\/li>\n<li>Length\/EtherType: 2 Bytes\n<ul>\n<li>Describes what is encapsulated in the Header<\/li>\n<li>Usually IPv4<\/li>\n<\/ul>\n<\/li>\n<li>Data: 46 &#8211; 1500 Bytes<\/li>\n<li>FCS (Frame Check Sequence): 4 Bytes\n<ul>\n<li>aka Redundancy check<\/li>\n<li>Used to check the integrity of the frame to ensure there hasn&#8217;t been any corruption.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h2>The Media Access Control (MAC) Address<\/h2>\n<ul>\n<li>Ethernet uses a 48 bit hexidecimal MAC Address<\/li>\n<li>The first 24 bits is the OUI (Organizationally Unique Identifier) which identifies the manufacturer of the Ethernet Port.\n<ul>\n<li>The OUI is assigned by the IEEE<\/li>\n<\/ul>\n<\/li>\n<li>The last 24 bits are vendor assigned.<\/li>\n<li>The burned in MAC address on every NIC port in the world is globally unique\n<ul>\n<li>Example: 00:50:56:C0:00:08<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h2>How to find your MAC Address<\/h2>\n<ul>\n<li>Windows:\n<ul>\n<li>ipconfig \/all<\/li>\n<\/ul>\n<\/li>\n<li>Linux:\n<ul>\n<li>ifconfig<\/li>\n<\/ul>\n<\/li>\n<li>Cisco Route\n<ul>\n<li>#show interface<\/li>\n<li>BIA = Burned In Address<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>&lt; Section 8 | Home | Section 10 &gt; 26% Completed 53: Introduction https:\/\/www.udemy.com\/cisco-icnd1\/learn\/lecture\/8601360#content 54: Local Are Network Layer 2 &#8211; Ethernet https:\/\/www.udemy.com\/cisco-icnd1\/learn\/lecture\/8601364#content Frames are encoded and decoded into bits at Layer 2 Error detection and correction for the physical layer can be provided here. Ethernet is the Layer 2 medium used on Local Area ..<\/p>\n<div class=\"clear-fix\"><\/div>\n<p><a href=\"https:\/\/wiki.thomasandsofia.com\/?p=2062\" title=\"read more...\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[45],"tags":[],"class_list":["post-2062","post","type-post","status-publish","format-standard","hentry","category-icnd1-ccent"],"_links":{"self":[{"href":"https:\/\/wiki.thomasandsofia.com\/index.php?rest_route=\/wp\/v2\/posts\/2062","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wiki.thomasandsofia.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wiki.thomasandsofia.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wiki.thomasandsofia.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/wiki.thomasandsofia.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2062"}],"version-history":[{"count":6,"href":"https:\/\/wiki.thomasandsofia.com\/index.php?rest_route=\/wp\/v2\/posts\/2062\/revisions"}],"predecessor-version":[{"id":2861,"href":"https:\/\/wiki.thomasandsofia.com\/index.php?rest_route=\/wp\/v2\/posts\/2062\/revisions\/2861"}],"wp:attachment":[{"href":"https:\/\/wiki.thomasandsofia.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2062"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wiki.thomasandsofia.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2062"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wiki.thomasandsofia.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2062"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}