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connected networks in routing protocol

Perhaps I need to re-read basic router configuration as this seems so fundamental. But here goes anyway:

I'm configuring eigrp across a 10mbps WAN link. The local WAN interface address is:

The remote address of course being:

On the local router I have a loopback address of:

My eigrp is configured with the following:

no auto-summary


My problem is this, the loopback address is appearing in the remote router's routing table. I don't want this to be happening.

A show IP protocols, displays routing for network:

The router is configured for IP classless.

What I don't understand is why eigrp is routing for:

when it should be:

Especially when: 1. I used a no auto-summary and 2. the loopback network address was not specifically entered as a part of the eigrp configuration.

Like I said, I know this is probably very basic. But as I understand it, eigrp is a hybrid distance-vector classless routing protocol. So I'm not sure why this is happening.

The IOS version on both ends is: 12.0(17)

Thank you for your-gentle-comments.



Re: connected networks in routing protocol

By default EIGRP will route for classfull networks even though it is a classless routing protocol, so it will advertise all your networks.

You can make it only advertise specific networks by using the MASK command (, however this was introduced in 12.0(4)T so you would need to upgrade your IOS.

Alternatively you could use a distribute list to filter out the loopback address in your updates.

Community Member

Re: connected networks in routing protocol


Thanks for your comments. Yea, I didn't see a "mask" sub-command when entering network statements.

I'll try your suggestions.

Thanks again.

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