Device with Public IP Address cannot access the Internet

[jeffrey.melendez1]

My organization recently had a service provider install an Ethernet Dedicated Internet service.  I received the IP address for the point-to-point connection with their equipment (50.XX.XX.180/30) where 50.XX.XX.182 is on my 3925 router.  I was also given a block of public IPs to use 50.XX.XX.64/28.  Gi0/0 (WAN interface) configured with 50.XX.XX.182/30.  Gi0/1 has several sub-interfaces (192.168.XX.XX).  I have configured the router to NAT all of the 192.168.XX.XX traffic to one of the public IPs received (50.XX.XX.66).  All of this is working without problems.  Now, when I configure Gi0/2 with one of the public IP addresses (50.XX.XX.65) and connect a 3850 switch to it, none of the devices that I then connect to that switch have access outside.  The switch also has a 50.XX.XX.67/28 configured and can successfully ping the gateway (50.XX.XX.65) and Gi0/0 of the router.  Beyond that, it cannot ping anything else.  Keep in mind that the devices I have connected to the switch have static IPs configured.  The router has only the default route of 0.0.0.0 0.0.0.0 50.XX.XX.181.  Gi0/0 has the ip nat outside statement and Gi0/1 has the ip nat inside.  Gi0/2 does not have any statements on it.  Can anyone provide recommendations as to what to look for?  Thanks in advance!

[Georg Pauwen]

Jeffrey,

post the configs of the switch and the router...

[Sam Smiley · Accepted solution]

Hi Jeffrey,

The issue really isn't an issue as you see it; your service provider has given you two subnets; 50.XX.XX.180/30 and 50.XX.XX.64/28. Their device is configured to send all traffic for 50.XX.XX.64/28 to 50.XX.XX.182. When you add another interface within to connect to the service provider all the routes for 50.XX.XX.64/28 are still being sent back to 50.XX.XX.182. In order to do what you want your service provider would have to assign a 3rd IP address to send the route.

There are a couple of ways you can configure this, I have a similar config in my own network. Assign gi0/0 on your 3925 as you have it to 50.XX.XX.182 with a gateway of 50.XX.XX.181. Then use NAT pools to distribute the 50.XX.XX.64/28 as needed. Here is an outline of what the config should look like:

https://supportforums.cisco.com/discussion/11738651/multiple-wan-ip-addresses-and-multiple-inside-hosts

Cheers,
Sam

[jeffrey.melendez1]

Well, apparently there was nothing wrong with my configuration.  I called up the service provider to verify my assigned block of IPs and it so happens that the ones I was given during the install were incorrect.  Once I reconfigured my interfaces with the correct ones everything began working.  Thank you all for your responses in this matter.