Slashdot: UK ISP PlusNet Testing Carrier-Grade NAT Instead of IPv6

William Herrin bill at
Fri Jan 18 14:03:31 UTC 2013

On Thu, Jan 17, 2013 at 11:15 PM, Constantine A. Murenin
<mureninc at> wrote:
> IPv6 is obviously the solution, but I think CGN poses more
> technological and legal problems for the carriers as opposed to their
> clients or the general-purpose non-server non-p2p application
> developers.

Correct. The most significant challenges to CGN are legal compliance
issues. NAT complicates the process of determining who did what using
the public IP at this timestamp. CGN developers have designed some
novel solutions to that problem, such as dedicating port ranges to
particular interior addresses and logging the range once instead of
trying to log every connection. So, don't expect it to be a show
stopper for long.

On the technical side, enterprises have been doing large-scale NAT for
more than a decade now without any doomsday consequences. CGN is not

> CGN breaks the internet, but it doesn't break non-p2p VoIP at all whatsoever.

Also correct. The primary impacts from CGN are folks who want to host
a game server, folks running bit torrent and folks who want to use
Skype. Skype's not stupid and voip relays are easy so after minor
growing pains that'll cease to be an issue too.

Make opting out of CGN simple and cheap. The relatively few folks who
would be impacted will opt out with no particular animus towards you
and you'll recover the IP addresses you had dedicated to the rest.

Bill Herrin

William D. Herrin ................ herrin at  bill at
3005 Crane Dr. ...................... Web: <>
Falls Church, VA 22042-3004

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