Cisco 2900 IP overlap

[Mbezayiff1]

So I have a 2900 router that I have configured the GI0/0 port with 10.1.209.266/24 and can ping the outgoing interface from the router however I'm trying to set up the GI0/1 port with an IP but keep getting an IP overlap when trying to put in a IP on that interface. I know that technically the 2 ports are in different Vlans but going up one subnet I am getting no where.

[Jon Marshall]

You can't use an IP from the 10.1.209.0/24 subnet on gi0/1, it would have to be from a different subnet. 

What are you trying to do ? 

Jon

[Mbezayiff1]

Trying to config the GI0/1 port with a viable IP to ping out to the interface. I placed a no ip on the GI0/1 and tried with a sub interface, installed a switch and I can hit the sub interface but still can hit the gi0/0 port, so somewhere my subnet calc's are off

[MHM Cisco World]

can you more elaborate issue I don't get it?

[Mbezayiff1]

so I changed the interface on the GI0/0 port to a /28 subnet, and can get to the outside, but still having an issue with the GI0/1 port where I'm not hitting the GI0/0 port 

[MHM Cisco World]

router have two port g0/0 and g0/1 
each one must have specific IP from different subnet, here use ONLINE subnet calculator to see if there is overlap or not
also
point to check

show ip interface brief <- check the interface is UP/UP

check if there is NAT between

[David Ruess]

Hello.

Are you trying to add an IP that's a /24 on one interface and a /28 on the other interface within the same network? If that's the case  and the /28 subnet falls within the /24 subnet, it will not work. As @Jon Marshall pointed out you cannot have IPs configured on a router on different interfaces in the same subnet. The /24 encompasses all 254 addresses. So a /28 network thats falls within those 254 addresses are not valid on the same router.

For example:

If your G0/0 interface was configured with 10.1.209.266/24 - that means no other interface on that router can be configured in the 10.1.209.1/24 subnet. If as you said you changed the G0/1 interface to a /28 subnet, if that /28 was something like 10.1.209.0/28 it wont works because that IP subnet falls within the /24 subnet from the other interface. You would need to configure something like 10.1.210.1/24.

Can you provide a diagram with labels and IPs you have configured to help understand better.

-David

[Mbezayiff1 · Accepted solution]

I set the GI0/0 port up for 10.1.209.0/28 and set the router GI0/0 port with .266 and I can ping out to the next interface, reset the GI0/1 port and reconfig'd it with a different ip/sub and can now ping from my laptop all the way. thanks

[Mbezayiff1 · Accepted solution]

So just to follow-up and correct myself as well, I changed the GI0/0 port to a 10.1.209.226 using 10.1.209.240/28 reset the outside interface to 10.1.209.225 and changed the subnet on the GI0/1 port with a valid IP and subnet, and it all works now. Too many changes occurring can be confusing at times. Again thanks