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Problems defining different IP addresses in the same router

The following problem ocurred to me recently. I have a Cisco 7500 with a subinterface whose IP address is 10.10.177.100/16 ( a whole B network is defined for the subinterface ). Then, I try to define another subinterface whose IP address is 10.10.10.0/30 ( point-to-point subinterface ) and I get the following message: IP address overlays 10.10.177.100.

The two IP addresses are actually independent subnets, so is this the normal behaviour??

The 'no ip classless' command is defined in the configuration. Could this have something to do with the error message?

Thanks,

Enrique

  • Other Network Infrastructure Subjects
1 REPLY
New Member

Re: Problems defining different IP addresses in the same router

You should not have overlapping IP space assigned to interfaces anywhere in your network. When you try to do this on two interfaces on the same router, you'll get the message you mentioned.

IP addresses should be unique across all devices and interfaces on your network. (Unless you use some kind of NAT translation).

10.10.10.0/30 is a subnet of 10.10.0.0/16. You might be confusing this scenario with the concept of route summarization. You could have 10.10.10.0/30 on an interface on the router, and then have a routing protocol, such as OSPF summarize the announce of the route as 10.10.0.0/16.

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