[137281] in North American Network Operators' Group
Re: Looking for an IPv6 naysayer...
daemon@ATHENA.MIT.EDU (Owen DeLong)
Thu Feb 10 16:01:02 2011
From: Owen DeLong <owen@delong.com>
In-Reply-To: <B9DA8B1C-17B5-483E-88E5-B14F30EF594C@queuefull.net>
Date: Thu, 10 Feb 2011 12:58:20 -0800
To: Benson Schliesser <bensons@queuefull.net>
Cc: NANOG list <nanog@nanog.org>, "Robert E. Seastrom" <rs@seastrom.com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Feb 10, 2011, at 8:05 AM, Benson Schliesser wrote:
>=20
> On Feb 10, 2011, at 9:53 AM, Jack Bates wrote:
>=20
>> On 2/10/2011 8:36 AM, Benson Schliesser wrote:
>>> DS-lite is still CGN.
>>=20
>> It is still LSN, but it is not NAT444, and the failure rate reduces =
because of that. Also, DS-Lite guarantees that you have IPv6 =
connectivity. NAT444 makes no such assertion.
>=20
> DS-lite *uses* IPv6 connectivity, it doesn't provide it. That's like =
saying 6rd or 6to4 "guarantees you have IPv4 connectivity".
>=20
> As for NAT444 (or double-NAT): One could just as easily deploy =
DS-lite with a NAT444 configuration. Or deploy CGN without NAT444 (e.g. =
CGN44, by managing subnets delegated to each subscriber). The two =
topics are related but separate.
>=20
I think that at the point where you go to NAT444 instead of tunneling =
the IPv4, it's Dual-Stack, but, not Dual-Stack-Lite.
> In terms of CGN44 versus NAT444, I'd like to see evidence of something =
that breaks in NAT444 but not CGN44. People seem to have a gut =
expectation that this is the case, and I'm open to the possibility. But =
testing aimed at demonstrating that breakage hasn't been very =
scientific, as discussed in the URLs I posted with my previous message.
>=20
Technologies which depend on a rendezvous host that can know about both =
sides of both NATs in a private->public->private
scenario will break in a private->private2->public->private2->private =
scenario. There are technologies and applications which
depend on this. (I believe, among others, that's how many of the p2p =
systems work, no?)
Owen
