Re: [v6ops] I-D Action:draft-ietf-v6ops-incremental-cgn-02.txt

[Rémi Després <[e-mail]>]

Hi Sheng, Diang, Brian,

The draft says 
"[ISPs]... currently face two urgent pressures - to compensate for an immediate shortage of IPv4 addresses by deploying some method of address sharing, and to prepare actively for the use of deployment of IPv6 address space and services. ISPs facing only one pressure out of   two could adopt either CGN (for shortage of IPv6 addresses) or 6rd."

This misses the point that 6rd can also be used by ISPs that, to face the IPv4 address shortage, operate CGN44s and assign private IPv4 addresses to their customers.
This is illustrated in particular in section 4 of RFC 5569:
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
              ______________________________
             |                              |
             | 10.x.x.x/8 private addresses |
             |  <==                         |
       <-----|         IPv4 anycast address |----->
             |            of 6rd relays     |
    6rd-CPEs |                      ==>     |  6rd-relays
             |                              |
       <-----|          0.0.0.0/0           |----->
             |              :               |
             |______________V_______________|
                          __|__
    ISP-supported NAT(s) |     |
                         |_____|
                            |
                            V
                 IPv4 public addresses
          Figure 3: 6rd Applicability to ISPs That Assign
                    IPv4 Private Addresses
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If a home gateway supports 6rd with the DHCPv4 option introduced in RFC 5969, the goal of incremental CGN seems to be reached with already specified mechanisms.

Thoughts?

Regards,
RD 



> A New Internet-Draft is available from the on-line Internet-Drafts directories.
> This draft is a work item of the IPv6 Operations Working Group of the IETF.
> 
> 
> 	Title           : An Incremental Carrier-Grade NAT (CGN) for IPv6 Transition
> 	Author(s)       : S. Jiang, D. Guo
> 	Filename        : draft-ietf-v6ops-incremental-cgn-02.txt
> 	Pages           : 13
> 	Date            : 2010-10-10
> 
> Global IPv6 deployment was slower than originally expected. As IPv4 
> address exhaustion approaches, the IPv4 to IPv6 transition issues 
> become more critical and less tractable. Host-based transition 
> 
> 
> mechanisms used in dual stack environments are not able to meet the 
> transition requirements. Most end users are not sufficiently expert 
> to configure or maintain host-based transition mechanisms. Carrier-
> Grade NAT (CGN) devices with integrated transition mechanisms can 
> reduce the operational change required during the IPv4 to IPv6 
> migration or coexistence period. 
> 
> This document proposes an incremental CGN approach for IPv6 
> transition. It can provide IPv6 access services for IPv6-enabled 
> hosts and IPv4 access services for IPv4 hosts while leaving much of a 
> legacy IPv4 ISP network unchanged. It is suitable for the initial 
> stage of IPv4 to IPv6 migration. Unlike NAT444 based CGN alone, 
> Incremental CGN also supports and encourages transition towards dual-
> stack or IPv6-only ISP networks. A smooth transition to IPv6 
> deployment is also described in this document. 
> 
> An integrated configurable CGN device and an adaptive Home Gateway 
> (HG) device are introduced. Both HG and CGN are re-usable devices 
> during different transition periods. It avoids potential multiple 
> upgrades. It enables IPv6 migration to be incrementally achieved 
> according to the real user requirements.
> 
> A URL for this Internet-Draft is:
> http://www.ietf.org/internet-drafts/draft-ietf-v6ops-incremental-cgn-02.txt
> 
> Internet-Drafts are also available by anonymous FTP at:
> ftp://ftp.ietf.org/internet-drafts/
> 
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