{"id":3955,"date":"2012-03-27T04:58:49","date_gmt":"2012-03-27T10:58:49","guid":{"rendered":"http:\/\/humairahmed.com\/blog\/?p=3955"},"modified":"2012-04-15T01:00:00","modified_gmt":"2012-04-15T07:00:00","slug":"eigrp-best-path-selection","status":"publish","type":"post","link":"https:\/\/humairahmed.com\/blog\/?p=3955","title":{"rendered":"EIGRP – Best Path Selection"},"content":{"rendered":"
\n\t\t\t\t\tTweet<\/a>\n\t\t\t\t<\/div><\/div>

By default EIGRP uses bandwidth and delay of the line to determine the best path to a remote network. However, if desired, EIGRP can use a composite of four metrics: bandwidth, delay, reliability, and load. Maximum transmission unit (MTU) is not used in EIGRP calculations but is a required parameter in some EIGRP-related commands. Also, by default, EIGRP will provide equal-cost load balancing across up to four links. You can disable load balancing by setting the \u2018maximum-paths\u2019 to \u20191\u2032. In this lab I use four Cisco 3725 routers [IOS 12.4(15)T10] to demonstrate EIGRP path selection behavior on Cisco routers. Below is a diagram of my setup.

\"EIGRP<\/a>

EIGRP lab topology<\/p><\/div>
\nMy initial topology and routing table is displayed below.

\"Initial<\/a>

Initial R1 EIGRP topology table<\/p><\/div>

\"Initial<\/a>

Initial R1 EIGRP routing table<\/p><\/div>
\nAs you can see from the above, since EIGRP provides equal-cost load balancing across for up to four links, both equal routes to the 12.0.0.0\/30 network are in the topology and routing table. Below, I lower the bandwidth of the 10.0.13.0\/30 link to 50 MB and since bandwidth is a metric used by EIGRP to determine the best path, you can see that the 10.0.13.0\/30 link remains in the topology table but is removed from the routing table. Only the 11.0.0.0\/30 link to the 12.0.0.0\/30 network remains in the routing table.

\"R1<\/a>

R1 EIGRP topology table after lowering the bandwidth of the 10.0.13.0\/30 link<\/p><\/div>

\"R1<\/a>

R1 EIGRP routing table after lowering the bandwidth of the 10.0.13.0\/30 link<\/p><\/div> <\/p>\n","protected":false},"excerpt":{"rendered":"

By default EIGRP uses bandwidth and delay of the line to determine the best path to a remote network. However, if desired, EIGRP can use a composite of four metrics: bandwidth, delay, reliability, and load. Maximum transmission unit (MTU) is … Continue reading →<\/span><\/a><\/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],"tags":[1181,4354,1114,1115,1116,1182,1183,609,1186,611,1112,613,610,298,1185,1184],"class_list":["post-3955","post","type-post","status-publish","format-standard","hentry","category-cisco","category-labs","category-networking","category-protocols","tag-bandwidth","tag-cisco","tag-cisco-3725","tag-cisco-3725-router","tag-cisco-3725-routers","tag-delay","tag-delay-of-the-line","tag-eigrp","tag-eigrp-calculation","tag-eigrp-load-balancing","tag-enhanced-interior-gateway-routing-protocol","tag-equal-cost-load-balancing","tag-load-balancing","tag-router","tag-routing-table","tag-topology-table"],"_links":{"self":[{"href":"https:\/\/humairahmed.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/3955","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=3955"}],"version-history":[{"count":20,"href":"https:\/\/humairahmed.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/3955\/revisions"}],"predecessor-version":[{"id":4195,"href":"https:\/\/humairahmed.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/3955\/revisions\/4195"}],"wp:attachment":[{"href":"https:\/\/humairahmed.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3955"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/humairahmed.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3955"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/humairahmed.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3955"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}