Can I create a subnet from the IPs assigned by my ISP?

robert-knapp · ‎09-15-2008

If my ISP has assigned the following range: 12.12.12.128/192 (26 bit mask), and their handoff is a serial T1 interface, can I:

1. assign 12.12.12.129/224 (27 bit mask) to S0/0 (for uplink to internet)

2. NAT the 12.12.12.129/224 (27 bit mask) network to the internal network on f0/0

3. assign 12.12.12.160/224 to F0/1. I will put this into a isolated switch for DMZ

Basiclly I want to split my 64 IPs into 2 networks but still route between them without any issues. Will this work? Will I need static routes?

merryllem · ‎09-15-2008

Yes it will work... don't forget to enter "ip classless" in global config. And of course "no auto-summary" if you are running Routing protocols

robert-knapp · ‎09-15-2008

Thanks for the info!