Eigrp - no auto-summary

Faizan Shaikh · ‎01-05-2009

I have configured eigrp between 2 routers.

rt#1

network 10.10.10.0

network 172.16.1.0

no auto summary

rt#2

network 20.20.20.0

network 172.16.1.0

no auto summary

when i do show ip route on both the routers. It gives the following output,

rt1#

10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

D 10.0.0.0/8 is a summary, 00:01:22, Null0

C 10.10.10.0/24 is directly connected, FastEthernet0/1

20.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

D 20.0.0.0/8 [90/30720] via 172.16.1.2, 00:00:44, FastEthernet0/0

D 20.20.20.0/24 [90/30720] via 172.16.1.2, 00:00:44, FastEthernet0/0

172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks

D 172.16.0.0/16 is a summary, 00:01:22, Null0

C 172.16.1.0/30 is directly connected, FastEthernet0/0

rt2#

10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

D 10.0.0.0/8 [90/30720] via 172.16.1.1, 00:00:13, FastEthernet0/0

D 10.10.10.0/24 [90/30720] via 172.16.1.1, 00:00:13, FastEthernet0/0

20.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

D 20.0.0.0/8 is a summary, 00:00:18, Null0

C 20.20.20.0/24 is directly connected, FastEthernet0/1

172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks

D 172.16.0.0/16 is a summary, 00:00:18, Null0

C 172.16.1.0/30 is directly connected, FastEthernet0/0

Why is it showing summarized routes?

Giuseppe Larosa · ‎01-06-2009

Hello Faizan,

have you added the no auto-summary in a second time ?

This could be a temporary effect

try the following

rt2# int f0/0

shut

! wait 60 seconds

no shut

Hope to help

Giuseppe

Richard Burts · ‎01-06-2009

Giuseppe

I am not clear why you think this might be a temporary effect or why you think that behavior might change if no auto-summary were configured a second time. I have never seen a router that needed this command to be entered a second time in order for it to take effect.

Faizan

The summary route is created by auto summarization or by manual summarization. I would guess that these routers are configured with summary-address on some interfaces. If you would post the output of show ip protocol it would help us to understand this. Even better would be to post the router configs so that we can see what is going on.

HTH

Rick

HTH

Rick

Giuseppe Larosa · ‎01-06-2009

Hello Rick,

I was wrong in my previous post looking at the time of the routes I saw only 15 seconds age for all the routes.

the effect of auto-summary should be immediate.

I agree that probably some summarization is taking place here.

Happy New Year

Best Regards

Giuseppe