In this lesson we’ll take a look at EIGRP summarization. The cool thing about EIGRP and summarization is that it’s easy to do and can be done on the interface level. Here’s the topology that we’ll use:
Let’s create a basic EIGRP configuration:
R1(config)#router eigrp 1 R1(config-router)#no auto-summary R1(config-router)#network 192.168.12.0 R1(config-router)#network 172.16.0.0
R2(config)#router eigrp 1 R2(config-router)#no auto-summary R2(config-router)#network 192.168.12.0
Just a basic EIGRP configuration. This is what the routing table of R2 looks like:
R2#show ip route eigrp 172.16.0.0/24 is subnetted, 2 subnets D 172.16.0.0 [90/30720] via 192.168.12.1, 00:02:28, FastEthernet0/0 D 172.16.1.0 [90/30720] via 192.168.12.1, 00:02:28, FastEthernet0/0
Two entries, as expected. Now let’s create that summary:
R1(config)#interface fastEthernet 2/0 R1(config-if)#ip summary-address eigrp 1 172.16.0.0 255.255.254.0
ip summary-address eigrp command to specify the summary. Now the routing table will look like this:
I have a question regarding ip summary-address command in above lesson.
By applying ip aummary-address command in fastethrnet 2/0 interface,
how come heart router know about the summary address.
As my understanding ip summary address is per interface basis.
I should apply ip summary-address in fastethernet 1/0 interface.
Would you correct me and help me to understand better.
I just changed the picture because the interface number didn’t match. You configure a summary outbound on an interface facing towards your EIGRP neighbor.
Simple but effective workout to understand EIGRP summerizing
thanks for the nice lesson, keep up the good work