EIGRP route summarization

Configuring Advanced EIGRP Options
1.EIGRP route summarization
In order to get the better network performance. You may configure EIGRP routing summarization
By implementing this options in your network,you will be able to have :
1. Smaller routing Update
2. Smaller routing table
You can configuring route summarization with EIGRP protocol with 2 ways ( Auto & Manual )
1. Route Summarization :Auto
On major network boundaries,subnets network are summarized to a single classfull ( Major ) network
Automatic summarization occur by default
2.Route Summarization : Manual
summarization is configured on per-basis interface in any router within a network
when summarization is configured,the router immediately creates a route pointing to null0 ( this is happened as the prevention looping mechanism )

when the last specific route of the summary goes away,the summary is deleted
the minimum metric of the specific routes is used as the metric of the summary route
Configuring route summarization :
(config-router)#no auto-summary
Turn off automatic summarization of EIGRP Process
(config-if)#ip summary-address eigrp as-number address mask
creates summary address that interface will be generate

Example :




From this picture ,router C sees network 172.16.1.0 and 172.16.2.0 but only sends 172.16.0.0 as the routing update to other network


Router C Completed configuration :
Router>enable
Router#configure terminal
Router(config)#router eigrp 100
Router(config-router)#network 10.0.0.0
Router(config-router)#network 192.168.4.0
Router(config-router)#exit
Router(config)#interface serial 0/0/0
Router(config-if)#ip address 192.168.3.2 255.255.255.0
Router(config-if)#ip summary-address eigrp 100 172.16.0.0 255.255.0.0