Subject: Re: Last Call: draft-ietf-v6ops-natpt-to-historic (Reasons to Move NAT-PT to Historic Status) to Informational RFC

From: Brian E Carpenter <[email-masked]>
Date: Thu, 01 Mar 2007 10:11:11 +0100

On 2007-02-28 17:02, Hallam-Baker, Phillip wrote:
> The core assumption here seems to be that NAT is a bad thing so lets get rid of NAT rather than trying to make NAT work.

This is startlingly irrelevant to the present document. We have a large corpus
of documents about the issues caused by NAT and about partial solutions. But
this document is about NAT-PT, which is something else.

> The questions that I would like to see answered that I don't see in the document are
> 
> 1) What is the deployment strategy for IPv6 without NAT?

As Fred has pointed out, there is also a large corpus of documents
about this, and it's clearly out of scope for the present document.

> 2) Are people actually using or deploying NAT-PT?

Had you read the draft carefully, you would know that
   "From a deployment perspective, 3GPP
    networks are currently the only 'standardised' scenario where an
    IPv6-only host communicates with an IPv4-only host using NAT-PT as
    described in the 3GPP IPv6 transition analysis [RFC4215], but NAT-PT
    has seen some limited usage for other purposes."

> 3) Exactly why should an application be invited to care about this issue?

Others have responded on this, but to summarise: an application that
assumes addresses have end to end validity will fail. That much, NAT-PT
has in common with NAT.

     Brian

---

From: [email-masked]
Date: Thu, 01 Mar 2007 03:39:21 -0700

Fred Baker writes: 

On Feb 28, 2007, at 8:02 AM, Hallam-Baker, Phillip wrote: 

> The core assumption here seems to be that NAT is a bad thing so  lets get 
> rid of NAT rather than trying to make NAT work.
> ...

Actually this has already been done, please see draft-ietf-v6ops-nap-06.txt 
which has been approved as an informational RFC (currently in the RFC 
editor's hands) for explanations as to why there is no NAT in IPv6. All we 
have is NAT-PT which is supposed to be an interconnection between IPv4 and 
IPv6 networks. And as the draft-ietf-v6ops-natpt-to-historic is proposing to 
do away with this last incident of the NAT abbreviation, even may be going 
away. 

The basic requirement for true end-to-end connectivity makes NAT in any form 
worth reconsidering.