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

Owen DeLong owen at
Fri Jan 18 17:36:50 UTC 2013

Sent from my iPad

On Jan 18, 2013, at 4:03 AM, William Herrin <bill at> wrote:

> 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
> different.

Yes it is... In the enterprise, whatever the security team decides isn't supposed to
be supported on the enterprise LAN, the end-users just sort of have to accept.

In the residential ISP world, unless every ISP in a given service area degrades all
of their customers in the exact same way, you have a very different situation.

>> 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.

An interesting theory, but I don't think it will be so few.


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