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ISP providing internet to future ISPs

I have site A as the central site where it is connected to the internet. On its second interface, 10 sites will also be connected thru a frame relay. Site A will be the one providing internet to other sites. The central site and all other site will allow dialup access to its remote sites. This other sites are schools that will act as ISP also.

Where will I provide NAT? Can i use private IP to link the serial connections? Do I need to configure NAT also to other sites? I was thinking that the other sites will surely want to host there own web servers, ftp, DNS. Anyone can help me with this? Thanks a lot.

[ Internet ]---[ Central site ]------[ Frame Relay ]------[ Site B, C, D...]


Re: ISP providing internet to future ISPs

In an enterprise environment, avoiding NAT at the central router is normally preferable as this eases the CPU overhead. If your public IP address space is severely limited, this will be the only way to accomplish your task. The NAT Technical Tips page provides a wealth of information on this very topic: