{"id":10,"date":"2015-08-19T01:45:04","date_gmt":"2015-08-19T01:45:04","guid":{"rendered":"http:\/\/wiki.thomasandsofia.com\/?p=10"},"modified":"2015-09-06T20:36:58","modified_gmt":"2015-09-06T20:36:58","slug":"ccent-2-s01-e04-addressing-fundamentals","status":"publish","type":"post","link":"https:\/\/wiki.thomasandsofia.com\/?p=10","title":{"rendered":"CCENT 2 S01 E04 &#8211; Addressing Fundamentals"},"content":{"rendered":"<h3>How does OSI Model and TCP\/IP Relate<\/h3>\n<ul>\n<li>OSI was a competing model with TCP\/IP in the 70&#8217;s<\/li>\n<li>It failed because addresses were too complex.\u00a0 Using HEX values and people never thought they would need that many.<\/li>\n<li>OSI MODEL is used to explain, but TCP\/IP is actually in use.<\/li>\n<li>Actually very similar to new IPv6 Protocols \ud83d\ude42<\/li>\n<li>TCP\/IP = DOD (Department of Defense)<\/li>\n<li>TCP\/IP is a SUIT of protocols working together<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<p><a href=\"http:\/\/wiki.thomasandsofia.com\/wp-content\/uploads\/2015\/08\/osi-tcpip_layers.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-17\" src=\"http:\/\/wiki.thomasandsofia.com\/wp-content\/uploads\/2015\/08\/osi-tcpip_layers.png\" alt=\"osi-tcpip_layers\" width=\"1038\" height=\"799\" srcset=\"https:\/\/wiki.thomasandsofia.com\/wp-content\/uploads\/2015\/08\/osi-tcpip_layers.png 1038w, https:\/\/wiki.thomasandsofia.com\/wp-content\/uploads\/2015\/08\/osi-tcpip_layers-300x231.png 300w, https:\/\/wiki.thomasandsofia.com\/wp-content\/uploads\/2015\/08\/osi-tcpip_layers-1024x788.png 1024w, https:\/\/wiki.thomasandsofia.com\/wp-content\/uploads\/2015\/08\/osi-tcpip_layers-150x115.png 150w\" sizes=\"auto, (max-width: 1038px) 100vw, 1038px\" \/><\/a><\/p>\n<h3>IP Addresses<\/h3>\n<p>Consists of 4 numbers (Each called an &#8216;octet&#8217;), ranging from 0-255: Ex. 172.30.5.82<\/p>\n<p>Always combined with a subnet mask and typically a default gateway:<\/p>\n<p>ip: 172.30.5.82<br \/>\nmask: 255.255.255.0<br \/>\ngw: 172.30.5.1<\/p>\n<p>Subnet Mask &#8211; 255=Network, 0=Host<br \/>\nAs long as network&#8217;s match, the hosts can communicate.<br \/>\nOne reason to split into different networks is to keep each network from getting so busy it can no longer communicate.<\/p>\n<p>Routers mark a dividing line between networks. No two interfaces of a router ever point to the same network.<br \/>\nJob 1: Routers stop broadcasts<\/p>\n<p>ARP: Address Resolution Protocol. Every computer on the network will receive the call asking for the MAC address for a specific IP.<\/p>\n<p>Computers do not &#8220;speak&#8221; to IP addresses, but is Layer 2, Data Link, MAC addresses.<\/p>\n<p><a href=\"http:\/\/wiki.thomasandsofia.com\/wp-content\/uploads\/2015\/08\/tcpip-network-diagram.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-18\" src=\"http:\/\/wiki.thomasandsofia.com\/wp-content\/uploads\/2015\/08\/tcpip-network-diagram.png\" alt=\"tcpip-network-diagram\" width=\"985\" height=\"330\" srcset=\"https:\/\/wiki.thomasandsofia.com\/wp-content\/uploads\/2015\/08\/tcpip-network-diagram.png 985w, https:\/\/wiki.thomasandsofia.com\/wp-content\/uploads\/2015\/08\/tcpip-network-diagram-300x101.png 300w, https:\/\/wiki.thomasandsofia.com\/wp-content\/uploads\/2015\/08\/tcpip-network-diagram-150x50.png 150w\" sizes=\"auto, (max-width: 985px) 100vw, 985px\" \/><\/a><\/p>\n<p>For computers to talk, if they are not on the same network (Subnet mask does not match),<br \/>\nExample: 10.1.1.10 wants to send to 10.5.5.100<br \/>\n1. .10 knows the receiving computer is not on it&#8217;s network because the network does not match.<br \/>\n2. .10 will ARP for the MAC address of the DEFAULT GATEWAY (DG) which is defined at setup.<br \/>\n3. Armed with the MAC for DG, it builds a packet with<br \/>\nSIP=10.1.1.10<br \/>\nDIP=10.5.5.100<br \/>\nSMAC = MAC for 10.1.1.10<br \/>\nDMAC = MAC for DF<br \/>\n4. Router looks at routing table, and sees the dest. IP Network is not connected, so will send to next router that it thinks &#8220;knows the way&#8221;, 10.2.2.2<br \/>\nSIP=10.1.1.10<br \/>\nDIP=10.5.5.100<br \/>\nSMAC = MAC for 10.2.2.1<br \/>\nDMAC = MAC for 10.2.2.2<br \/>\n5. Continue until you find router with correct Network, 10.5.5.xxx<\/p>\n<h3><strong>Default Address Classes &#8211; MEMORIZE!!<\/strong><br \/>\nThree Usable Classess of Addresses:<\/h3>\n<p>127.x.x.x reserved for &#8220;loopback&#8221;<\/p>\n<p><strong>Class A:<\/strong><br \/>\nFirst octet of IP addresses is 1 &#8211; 126 (ex: 10.5.1.1, Network = 10, Host = 5.1.1)<br \/>\nHas Subnet Mask 255.0.0.0<br \/>\n16,777,214 Hosts!<\/p>\n<p><strong>Class B:<\/strong><br \/>\nFirst Octet of IP Address is 128 &#8211; 191 (ex: 150.51.233.1, Network = 150.51, Host = 233.1)<br \/>\nHas Subnet Mask 255.255.0.0<br \/>\n65,536 Hosts<\/p>\n<p><strong>Class C:<\/strong><br \/>\nFirst Octet of IP Address is 192 &#8211; 223 (ex: 220.1.50.63, Network = 220.1.50, Host = 63)<br \/>\nHas Subnet Mask 255.255.255.0<br \/>\n254 Usable Hosts<\/p>\n<h3>Differences between Public and Private Addresses<\/h3>\n<p><b>Public Addresses<\/b><\/p>\n<ul>\n<li>Aquired from ISP<\/li>\n<li>Usable on the Internet (Public) Networks<\/li>\n<li>Useable on Internal (Private) Networks<\/li>\n<\/ul>\n<p><b>Private Addresses<\/b><\/p>\n<ul>\n<li>Usable on the Internal (Private) Networks ONLY<\/li>\n<li>These addresses CANNOT communicate directly onto the Internet!! [Achieved via NAT &#8211; See Below]<\/li>\n<li>Three Ranges &#8211; MEMORIZE:<\/li>\n<\/ul>\n<ol>\n<li>Class A: 10.0.0.0 &#8211; 10.255.255.255<\/li>\n<li>Class B: 172.16.0.0 &#8211; 172.31.255.255<\/li>\n<li>Class C: 192.168.0.0 &#8211; 192.168.255.255<\/li>\n<\/ol>\n<ul>\n<li>Loopback range used for testing: 127.x.x.x (Only available to itself)<\/li>\n<li>Auto-Configuration range: 169.254.x.x (If a host cannot get an IP via DHCP and can only communicate on its own local network.)<\/li>\n<\/ul>\n<h3><\/h3>\n<h3>Basics of NAT (Network Address Translation)<\/h3>\n<ul>\n<li>Purpose is to preserve Public IP Space.\u00a0 Without NAT, we would have ran out of IPs long ago!<\/li>\n<li>Allows potentially thousands of Private IPs to share a Public IP Address.<\/li>\n<li>Router gets a PUBLIC IP from ISP.<\/li>\n<li>All devices in home\/business use Private IPs<\/li>\n<li>As traffic going from the Network to the Internet, the Router &#8220;hides&#8221; the private IP and replaces it with the Public IP.<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<h3>Notes:<\/h3>\n<p>Cisco recommends not to use more than 500 Hosts per network<\/p>\n","protected":false},"excerpt":{"rendered":"<p>How does OSI Model and TCP\/IP Relate OSI was a competing model with TCP\/IP in the 70&#8217;s It failed because addresses were too complex.\u00a0 Using HEX values and people never thought they would need that many. OSI MODEL is used to explain, but TCP\/IP is actually in use. Actually very similar to new IPv6 Protocols ..<\/p>\n<div class=\"clear-fix\"><\/div>\n<p><a href=\"https:\/\/wiki.thomasandsofia.com\/?p=10\" 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":[3,2,10],"tags":[],"class_list":["post-10","post","type-post","status-publish","format-standard","hentry","category-ccent","category-networking","category-tcpip"],"_links":{"self":[{"href":"https:\/\/wiki.thomasandsofia.com\/index.php?rest_route=\/wp\/v2\/posts\/10","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=10"}],"version-history":[{"count":3,"href":"https:\/\/wiki.thomasandsofia.com\/index.php?rest_route=\/wp\/v2\/posts\/10\/revisions"}],"predecessor-version":[{"id":20,"href":"https:\/\/wiki.thomasandsofia.com\/index.php?rest_route=\/wp\/v2\/posts\/10\/revisions\/20"}],"wp:attachment":[{"href":"https:\/\/wiki.thomasandsofia.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wiki.thomasandsofia.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wiki.thomasandsofia.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}