{"id":4280,"date":"2012-06-01T02:31:21","date_gmt":"2012-06-01T08:31:21","guid":{"rendered":"http:\/\/humairahmed.com\/blog\/?p=4280"},"modified":"2012-06-01T06:05:19","modified_gmt":"2012-06-01T12:05:19","slug":"configuring-ospf-with-multiple-areas","status":"publish","type":"post","link":"https:\/\/humairahmed.com\/blog\/?p=4280","title":{"rendered":"Configuring OSPF with Multiple Areas"},"content":{"rendered":"
\n\t\t\t\t\tTweet<\/a>\n\t\t\t\t<\/div><\/div>

In this lab, I use three Cisco 3725 routers [IOS 12.4(15)T10] to demonstrate how to setup OSPF with multiple Areas. Below is the network diagram for this lab.

\"Lab<\/a>

Lab Diagram<\/p><\/div><\/p>\n

Setup basic configuration on all routers:<\/u><\/strong>
\n
R1<\/strong><\/p>\n

\n– enable
\n– configure terminal
\n– interface fastEthernet 0\/0
\n– ip address 14.0.0.1 255.255.255.0
\n– no shutdown
\n– exit
\n– interface serial 0\/0
\n– ip address 12.0.0.1 255.255.255.252
\n– no shutown
\n– exit
\n– interface loopback 1
\n– ip address 1.1.1.1 255.255.255.255
\n– exit
\n– exit
\n– write\n<\/p><\/blockquote>\n

\nR2<\/strong><\/p>\n

\n– enable
\n– configure terminal
\n– interface serial 0\/0
\n– ip address 12.0.0.2 255.255.255.252
\n– no shutdown
\n– interface serial 0\/1
\n– ip address 13.0.0.1 255.255.255.252
\n– no shutdown
\n– exit
\n– interface loopback 2
\n– ip address 2.2.2.2 255.255.255.255
\n– exit
\n– exit
\n– write\n<\/p><\/blockquote>\n

\nR3<\/strong><\/p>\n

\n– enable
\n– configure terminal
\n– interface serial 0\/0
\n– ip address 13.0.0.2 255.255.255.252
\n– no shutdown
\n– interface fastEthernet 0\/0
\n– ip address 15.0.0.1 255.255.255.0
\n– no shutdown
\n– exit
\n– interface loopback 3
\n– ip address 3.3.3.3 255.255.255.255
\n– exit
\n– exit
\n– write\n<\/p><\/blockquote>\n

Setup OSPF on all routers:<\/u><\/strong>
\n
R1<\/strong><\/p>\n

\n– enable
\n– configure terminal
\n– router ospf 1
\n– network 12.0.0.0 0.0.0.3 area 1
\n– network 14.0.0.0 0.0.0.255 area 1
\n– network 1.1.1.1 0.0.0.0 area 1
\n– exit
\n– exit
\n– write\n<\/p><\/blockquote>\n

\nR2<\/strong><\/p>\n

\n– enable
\n– configure terminal
\n– router ospf 2
\n– network 12.0.0.0 0.0.0.3 area 1
\n– network 13.0.0.0 0.0.0.3 area 0
\n– network 2.2.2.2 0.0.0.0 area 0
\n– exit
\n– exit
\n– write\n<\/p><\/blockquote>\n

\nR3<\/strong><\/p>\n

\n– enable
\n– configure terminal
\n– router ospf 3
\n– network 13.0.0.0 0.0.0.3 area 0
\n– network 15.0.0.0 0.0.0.255 area 0
\n– network 3.3.3.3 0.0.0.0 area 0
\n– exit
\n– exit
\n– write\n<\/p><\/blockquote>\n

Below are some useful OSPF commands that can be used for troubleshooting\/verification.<\/p>\n

OSPF Ping Test From R1: <\/u><\/strong>
\n

\"OSPF<\/a>

OSPF Ping Test<\/p><\/div><\/p>\n

___________________________________________________________________________________<\/strong>
\n
Verification from R2:<\/u><\/strong><\/p>\n

show ip ospf interface brief<\/u><\/strong>
\n

\"show<\/a>

show ip ospf interface brief<\/p><\/div><\/p>\n

show ip protocols<\/u><\/strong>
\n

\"show<\/a>

show ip protocols<\/p><\/div><\/p>\n

show ip ospf neighbor<\/u><\/strong>
\n

\"show<\/a>

show ip ospf neighbor<\/p><\/div><\/p>\n

An Area Border Router (ABR) is a router that belongs to two areas; it creates a summary of the prefixes in one area and announces it to the other area as a LSA Type 3. In every LSA Type 3, the ABR router puts itself as next-hop for the route. In the below output, you can see R2 is generating the LSA Type 3 packets respectively for R1 and R3.<\/p>\n

show ip ospf database<\/u><\/strong>
\n

\"show<\/a>

show ip ospf database<\/p><\/div><\/p>\n

show ip route<\/u><\/strong>
\n

\"show<\/a>

show ip route<\/p><\/div>
<\/p>\n","protected":false},"excerpt":{"rendered":"

In this lab, I use three Cisco 3725 routers [IOS 12.4(15)T10] to demonstrate how to setup OSPF with multiple Areas. Below is the network diagram for this lab.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[297,296,295,747,3,821],"tags":[1263,1266,4354,1114,1115,1264,1265,372,934,1267,298],"class_list":["post-4280","post","type-post","status-publish","format-standard","hentry","category-cisco","category-labs","category-networking","category-protocols","category-technology","category-troubleshooting","tag-area","tag-areas","tag-cisco","tag-cisco-3725","tag-cisco-3725-router","tag-multiple-areas","tag-multiple-ospf-areas","tag-ospf","tag-ospf-area","tag-ospf-areas","tag-router"],"_links":{"self":[{"href":"https:\/\/humairahmed.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/4280","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/humairahmed.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/humairahmed.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/humairahmed.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/humairahmed.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=4280"}],"version-history":[{"count":59,"href":"https:\/\/humairahmed.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/4280\/revisions"}],"predecessor-version":[{"id":4356,"href":"https:\/\/humairahmed.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/4280\/revisions\/4356"}],"wp:attachment":[{"href":"https:\/\/humairahmed.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4280"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/humairahmed.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4280"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/humairahmed.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4280"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}