[137148] in North American Network Operators' Group
RE: Looking for an IPv6 naysayer...
daemon@ATHENA.MIT.EDU (George Bonser)
Wed Feb 9 16:36:25 2011
Date: Wed, 9 Feb 2011 13:33:51 -0800
In-Reply-To: <4D5306EB.3030203@ispalliance.net>
From: "George Bonser" <gbonser@seven.com>
To: "Scott Helms" <khelms@ispalliance.net>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
>=20
> 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.
>=20
> 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.
