[arin-ppml] ARIN-prop-127: Shared Transition Space for IPv4 Address Extension

Lee Howard spiffnolee at yahoo.com
Thu Jan 20 13:51:25 EST 2011

> For the use proposed, /10 is not enough space. 

A /10 is probably enough for the inside of any single Large-Scale NAT.
It's actually a pretty large failure domain.

> It is also a use which is  not region 
> specific, and wasteful for each region to specify their own space for  such 

ISPs in the ARIN region would use this space.  I don't care if ISPs outside the
ARIN region also use it, since I'll never see the routes.
It would be wasteful if every ISP was allocated a prefix to use for the inside
of their NAT.  If would also be wasteful for each RIR to allocate a prefix for
the same use.

> > Until such customers replace their Home Gateways and  all IPv4-only
> > devices with IPv6-capable devices, Service Providers will  be required to
> > continue to offer IPv4 services through the use of an  IPv4 address
> > sharing technology such as NAT444. A recent study showed  that there is
> > no part of RFC1918 space which would not overlap with some  IPv4
> > gateways, and therefore to prevent address conflicts, new address  space
> > is needed.
> Overlap with home gateway addressing is not a  concern of ARIN. RFC1918
> could be utilized and home gateways reconfigured if  necessary.

How would that work?  Hundreds of millions of home gateways are already
deployed; how do they get reconfigured?

>  It is wasteful 
> to allow a small percentage of possible conflicts to  warrant additional space. 

There's a survey at http://member.wide.ad.jp/tr/wide-tr-kato-as112-rep-01.pdf
showing conflicts.  It's not small.

> The larger conflict of RFC1918 space is cpe management  addressing which 
> used RFC1918, in which case, a very large cable company just  ran out and 
> had to request addressing to support this case. A /10 wouldn't come  close to 
> supporting that many  subscribers.

If LSNs were deployed regionally, and OSS were inside the LSN scope, you
could reuse pretty well.

Though I have some misgivings about the general idea, and though I will go
to great lengths to avoid the use of Large Scale NAT, if it is required, then
unique address space will be required for it.  Therefore, I support this


> Jack
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