Adding private IPs

[pabloch2]

I have a little LAN with 3 PCs running windows XP Professional with
only one network adapter per PC. They are connected to a switch. Each
PC must use a special application and they must have a different public
IP address (they can not access Internet via NAT with only one external
IP, each IP must be used with only one client)
My ISP gave me a cablemodem. It has a built in DHCP that gives public
and dynamic IP addresses for each PC.
If each PC has a public and dynamic IP ¿How can I connect them
internally in the LAN? I can only think in three possibilities, but I
am not satisfied with any of them

1) I could use the public IPs for the LAN, but I would be exposing
resources to the Internet and I don't know how the name resolution
would work in the LAN.

2) I could use other protocols for the LAN, perhaps IPX or netbeui, but
I refuse to do that, it's a dirty solution.

3) I could add another IP for each adapter. But if I manually add IPs I
can not use the DHCP of the cablemodem. I need one IP assigned by the
DHCP and another one assigned by me.

¿What can be done?

 

[Yves Leclerc]

You need to check in the cablemodem so as to see if the public IP addresses
can be "forwarded" to the private IP addresses.