EIGRP route summarization issue

[mahesh18]

Hi All,

I have question about EIGRP route summarization

Router 1 has following Loopback IPs

10.2.2.1

10.2.3.1

10.2.4.1

10.2.5.1

10.2.6.1

10.2.7.1

10.2.8.1

10.2.9.1

R1 is EIGRP nei to R2

To advertise the summary route I do this under R1 serial interface

Ip summart-address eigrp 100 10.2.0.0 255.255.248.0

As IP address in EIGRP the first IP always start with 0.0 that’s why I choose 10.2.0.0

Subnet mask I choose is 255.255.248.0 is this correct?

Now when I do s hip route on R2 it still shows following 2 IPs

10.2.8.0

10.2.9.0

So these two are not included under summary address any reason?

Thanks

Mahesh

[siddhartham · Accepted solution]

10.2.0.0 255.255.248.0 means 10.2.0.1 to 10.2.7.254--- this doesn't include 10.2.8.0 and 10.2.9.0.

to include 2.8 and 2.9, you have to choose a bigger mask 255.255.240.0 this will cover 10.2.0.1 to 10.2.15.254

[John Blakley · Accepted solution]

Mahesh,

I show your summary address as:

10.2.2.0 255.255.240.0

10.2.0.0 255.255.240.0

HTH,

John

[rizwanr74 · Accepted solution]

Hi John,

Your summary also includes networks 10,11,12,13,14 and 15.

therefore, Mahesh you would need to block, "10,11,12,13,14, and 15" and do not forget to deny network 0 and 1 as well via ACL if you want to.

thanks

Rizwan Rafeek

Message was edited by: Rizwan Mohamed

[mahesh18]

Hi all,

It is working fine now

i used summary address 10.2.0.0 255.25.240.

Thanks everyone for their help

Thanks

MAhesh

[mahesh18]

Hi John,

Yes the subnet mask is 255.255.240.0  i got this by doing binary method

Will try this in my  config and will let you know

Thanks

Mahesh