[arin-ppml] ARIN-prop-127: Shared Transition Space for IPv4Address Extension

George, Wes E [NTK] Wesley.E.George at sprint.com
Fri Jan 21 17:08:57 EST 2011


> -----Original Message-----
> From: arin-ppml-bounces at arin.net [mailto:arin-ppml-bounces at arin.net] On
> Behalf Of George Bonser
> Sent: Friday, January 21, 2011 4:54 PM
> To: Chris Donley; Chris Grundemann
> Cc: arin-ppml at arin.net
> Subject: Re: [arin-ppml] ARIN-prop-127: Shared Transition Space for
> IPv4Address Extension
> 
> 
> Why is it going to suck?  We are actually doing it now, pretty much.  A
> computer in an office opens a connection to a content provider.  That
> RFC1918 packet gets NATed to a global IP somewhere.  That packet then
> hits a load balancer at the content provider where it is again
> translated and directed to a machine in 1918 space again.
> 
> For all practical purposes most of the traffic in the v4 Internet today
> is already NAT444
> 
> In and of itself it isn't going to break anything that doesn't already
> break today unless someone tries to use an underpowered box to do the
> NAT.

[WES] No. What you describe is two separate instances of NAT44 talking to
each other.
NAT444 is specifically where there are two layers of NAT before the end
host's packets see the light of day on the public Internet. That is, host
(CPE NATbox) (ISP NATbox) Internet. The CPE NATbox doesn't get a unique
address and its NATted traffic must be NATted through the ISP NATbox in
order to do anything useful, and the first unique routable address is on the
outside of the ISP NATbox. Many of the things that work properly through one
layer of NAT do so because of helper protocols like UPnP that punch holes in
the NAT, and because programmers have worked very hard to find ways to make
their stuff continue working with NAT. NAT444 is not going to work like that
for a lot of different reasons.

Citations of useful reading material, a lot of it from the joint sessions
from ARIN/NANOG last fall:
http://tools.ietf.org/html/draft-donley-nat444-impacts-00

Cox Communications Service Provider NAT44
http://nanog.org/meetings/nanog50/presentations/Wednesday/NANOG50.Talk65.wei
l-SP%20NAT44.pdf

Time Warner Cable Address Sharing issues:
http://nanog.org/meetings/nanog50/presentations/Wednesday/NANOG50.Talk65.How
ard-Addresssharingproblems.pdf

Comcast DS-lite:
http://nanog.org/meetings/nanog50/presentations/Wednesday/NANOG50.Talk65.DS-
lite%20NANOG50%20v1.1.pdf

Note - panel discussion that several of these source presentations are from
can be streamed here:
https://www.arin.net/participate/meetings/reports/ARIN_XXVI/webcast/howard_i
pv4_to_ipv6_mechanisms.mov

Research into the Viability of Service-Provider NAT (session lifetime and
average sessions per user):
http://www.wand.net.nz/~salcock/someisp/flow_counting/result_page.html

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