[c-nsp] Overlapping Subnet Issue - Gateway IP Resides in Vendor Assigned Public IP Range

[Seth Mattinen]

On 7/9/12 3:13 PM, Spencer Barnes wrote:
> Hello,
> 
> I'm trying to move to a new ISP.  Our old one provided a T3 and an external IP range.  The gateway IP they gave to us to assign to our router interface was on a different subnet than the external IPs they provided so having another interface dedicated to the external network was an easy setup.
> 
> Our new ISP provided a gateway IP that is in the same subnet as the external IPs they provided for use.  The range they provided (changed for security) is 10.0.128.64/26.  They want us to assign 10.0.128.66 to our WAN interface and point all outbound traffic to 10.0.128.65.
> 
> The problem with this setup is I can't dedicate another interface for the new external range because the subnets overlap.  I can change the g0/0 interface to 10.0.128.66 255.255.255.252 and assign the other interface g0/1 10.0.128.96 255.255.255.224 but then I lose a bunch of external IPs.
> 
> Is there a better way to do this so I can use all the IPs in the range?
> 
> Thanks in advance for any input.


Ask your new ISP for a /30 for their side of the connection and to route
your subnet to you over it.

~Seth