No Auto-Summary Command on CISCO Router/Switch

Command

No Auto-Summary

Use

Disables EIGRP’s default behavior to advertise networks at their classful boundary.

Syntax

Router(config-router)#no auto-summary

Example

In this example, we will disable auto-summary in the EIGRP process and observe the difference. First we will enable EIGRP on all routers for all links.

R1(config)#router eigrp 100
R1(config-router)#network 0.0.0.0

Notice the EIGRP routes are currently shown at their classful boundaries.

R1(config)#do show ip route eigrp
1.0.0.0/8 is variably subnetted, 4 subnets, 2 masks
D 1.0.0.0/8 is a summary, 00:00:50, Null0
192.168.13.0/24 is variably subnetted, 2 subnets, 2 masks
D 192.168.13.0/24 is a summary, 00:00:51, Null0
D 2.0.0.0/8 [90/156160] via 10.1.1.2, 00:00:50, FastEthernet0/0
D 33.0.0.0/8 [90/158720] via 10.1.1.2, 00:00:51, FastEthernet0/0
D 3.0.0.0/8 [90/158720] via 10.1.1.2, 00:00:51, FastEthernet0/0
111.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
D 111.0.0.0/8 is a summary, 00:00:50, Null0
10.0.0.0/8 is variably subnetted, 4 subnets, 2 masks
D 10.2.2.0/24 [90/30720] via 10.1.1.2, 00:00:51, FastEthernet0/0
D 10.0.0.0/8 is a summary, 00:00:51, Null0
11.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
D 11.0.0.0/8 is a summary, 00:00:50, Null0
D 133.133.0.0/16 [90/158720] via 10.1.1.2, 00:00:51, FastEthernet0/0

Now we will type no auto-summary on all routers.

R1(config)#router eigrp 100
R1(config-router)#no auto

After typing the command, we now see the proper network information.

R1(config)#do show ip route eigrp
2.0.0.0/32 is subnetted, 1 subnets
D 2.2.2.2 [90/156160] via 10.1.1.2, 00:00:37, FastEthernet0/0
33.0.0.0/32 is subnetted, 1 subnets
D 33.33.33.33 [90/158720] via 10.1.1.2, 00:00:37, FastEthernet0/0
3.0.0.0/32 is subnetted, 1 subnets
D 3.3.3.3 [90/158720] via 10.1.1.2, 00:00:37, FastEthernet0/0
10.0.0.0/24 is subnetted, 3 subnets
D 10.2.2.0 [90/30720] via 10.1.1.2, 00:00:37, FastEthernet0/0
133.133.0.0/32 is subnetted, 1 subnets
D 133.133.133.133 [90/158720] via 10.1.1.2, 00:00:37, FastEthernet0/0

Related Articles

Leave a Reply

avatar