%Inconsistent address and mask

[Meri Christmas]

Our ISP has set up a modem at our location with the following IP and subnet:

ip 96.74.187.50

mask 255.255.255.252

I'm trying to put in an ip route to the next hop which is our firewall

switch> ip route 96.74.187.50 255.255.255.252 10.10.22.5

when I do this I get %inconsistent address and mask

We were given the ip and mask by our ISP. I'm a newbie and not sure how to fix this issue.

HELP!

[Meheretab Mengistu · Accepted solution]

Hi,

When you create static routes, you will need to enter the network ID (not the IP address assigned to your firewall) and the subnet mask. In your case, your network Id is 96.74.187.48. As a result, your static route should be:

ip route 96.74.187.48 255.255.255.252 10.10.22.5

HTH,

Meheretab

[Meri Christmas]

Thank you Meheretab

Being a newbie I had to break it down into binary and came up with the network address in your post.

I knew I should have used it!

I spoke with a colleague and he told me that was wrong, so glad I posted here.

Thanks again.

[crixogus10044]

por que?

[Richard Burts]

The original attempt to configure a static route was ip route 96.74.187.50 255.255.255.252 10.10.22.5 

If we look at the mask of 255.255.255.252 this indicates a subnet of /30. And that means that the first 28 bits of the address represent the subnet and are significant while the last 4 bits of the address are host address bits and are not significant. But looking at the address in the route 96.74.187.50 we find that some of the host bits are not zero. So the address specified is inconsistent with the mask used.

[genefrehleyjaleco404]

i have problem on static routing my network address is 20.79.23.0 255.255.248.0 10.70.20.1

[Georg Pauwen]

Hello,

what is the context of your question ?

[Richard Burts]

I agree with @Georg Pauwen that the context of the question is not so clear. But remembering that this post is added to a discussion of static routes where the address specified in the static route is not consistent with the mask used in the static route we can see that this post raises the same issue. The address given is 20.79.23.0 with a mask of 255.255.248.0. With that mask the correct address to use would be 20.79.16.0. 

Or if that address is really the address intended then the mask would need to be 255.255.255.0. The important thing is that the address used must be consistent with the mask used.

[Georg Pauwen]

That has to be it, good catch !

Router(config)#ip route 20.79.23.0 255.255.248.0 10.70.20.1
%Inconsistent address and mask
Router(config)#ip route 20.79.16.0 255.255.248.0 10.70.20.1
Router(config)#