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

Owen DeLong owen at delong.com
Thu Jan 20 13:44:44 EST 2011

Sent from my iPad

On Jan 20, 2011, at 8:36 AM, Jack Bates <jbates at brightok.net> wrote:

> Oppose prop 127
> On 1/20/2011 10:26 AM, ARIN wrote:
>> Updates 4.10 of the NRPM:
>> A second contiguous /10 IPv4 block will be reserved to facilitate IPv4
>> address extension. This block will not be allocated or assigned to any
>> single organization, but is to be shared by Service Providers for
>> internal use for IPv4 address extension deployments until connected
>> networks fully support IPv6. Examples of such needs include: IPv4
>> addresses between home gateways and NAT444 translators.
> For the use proposed, /10 is not enough space. It is also a use which is not region specific, and wasteful for each region to specify their own space for such purposes.
Given that this space can be duplicated even within a service providers network as long as each instance of the addressing is isolated to a particular NAT or set of NATs, I think a /10 is plenty and possibly excessive. I would certainly oppose removing more than a /10 from other uses to facilitate this.

As to the regional issue, I doubt that every region will create a block like this. I believe that this is currently only being proposed within the ARIN region and that if we do adopt this proposal, I suspect that the space we set aside would be used globally and that other regions would not create separate blocks for the same purpose.

>> 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. It is wasteful to allow a small percentage of possible conflicts to warrant additional space. 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.
In general, I am inclined to agree with this argument. However I think calling it a small percentage of possible conflicts is not an accurate characterization of the problem. The home gateway market seems to have a relatively random distribution of defaults across all of the RFC-1918 prefixes.


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