on interface multiple IP's

Unanswered Question
Jul 8th, 2009

Can someone point me to a doc that explains how to configure a DSL wan interface on an 881 to have multiple static IP's?

Thanks in advance,


I have this problem too.
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Brent Rockburn Wed, 07/08/2009 - 07:55

Thanks, but I meant a CISCO config page on how to configure multiple IP's on the WAN interface of a c881.

Paolo Bevilacqua Wed, 07/08/2009 - 08:06

Please explain what do you want to do with the multiple IPs as the configuration depends by that.

Brent Rockburn Wed, 07/08/2009 - 08:10


I have a provider that will give me a DSL line an 5 possible IP's.

I want to harness all 5 ip's. So how do I configure the outside interface to have several of these IP's. I assume a sub interface will come into play. It's static on the provider side so there is no need for a dialer interface.

Paolo Bevilacqua Wed, 07/08/2009 - 08:16

You can configure secondary addresses, but that won't give you any benefit.

Once you decide a real use for the IP (eg, VPN termination, special NAT, management), a configuration can be suggested.

Brent Rockburn Wed, 07/08/2009 - 08:20

Special NAT would probably be the most useful.

But I'd just like to know how to get the other IP's functioning off the one interface regardless of what my use for it is.

Rick Morris Wed, 07/08/2009 - 12:33

Paolo is correct, you need to explain what you want to do before any suggestions can be made.

Are you using these for NAT-ing to a private IP inside?

Are you assigning these IP's to hosts?

Do you just want the IP's for outbound routing?

Do you just want the IP range for use because you have it and have no idea what to do with it?

What do you want to accomplish and a suggestion can be made. Your question is vague and the follow-up is not specific enough.

Richard Burts Wed, 07/08/2009 - 13:21


I would suggest that using secondary addressing is probably not the way to make most effective use of the extra addresses. My suggestion would be to configure a NAT pool of addresses using the extra addresses and translate traffic from inside going to the Internet with the NAT pool. Or perhaps you might want to use some of the extra addresses and do static NAT for some inside devices so that some inside servers might have permanent assignment of Internet reachable addresses.



Paolo Bevilacqua Wed, 07/08/2009 - 14:22

Said above:

You can configure secondary addresses, but that won't give you any benefit.

As mentioned already:

First say what you want

Then something can be suggested


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