> > Comcast, like all(?) DOCSIS systems uses 10/8 or one of the other > defined non-routable blocks for cable modems, which (if its a DOCSIS > certified device) will be a bridge only and will not do NAT. If you > we're NAT'ed on a cable modem system it must have been a proprietary > system, of which there once was a ton before DOCSIS caught on, that > Comcast hadn't phased out. > > I don't believe that any of the large MSO's (and none of the small ones > I know) are doing NAT on edge devices or the core at this point, > however > your point is still valid since virtually all of the ADSL lines
I can log in to the Two Wire device on my AT&T Uverse service and see the NAT configuration. It has a global IP on the Internet side and it has a DHCP server handing out RFC1918 addresses on the inside network. I can also configure some settings which allow certain applications inside to map to specific ports on the global IP. When I had Comcast, I am not positive where the NAT was being done, but my computer got an RFC1918 IP when it did DHCP.
