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

Owen DeLong owen at delong.com
Fri Jan 21 05:17:35 EST 2011

On Jan 21, 2011, at 1:31 AM, Mark Smith wrote:

> Hi William,
> On Thu, 20 Jan 2011 16:22:22 -0500
> William Herrin <bill at herrin.us> wrote:
>> On Thu, Jan 20, 2011 at 4:10 PM, Mark Smith
>> <ipng at 69706e6720323030352d30312d31340a.nosense.org> wrote:
>>> Why should the global Internet community (i.e. the end-users of
>>> the Internet) have to help wear the costs of individual ISPs not
>>> deploying IPv6 quickly enough?
>> Hi Mark,
>> It seems to me that "whose fault is it?" matters less than "what do we
>> do now?" What we do now is lessen the transition problems (so that the
>> end users don't get screwed in the short term) while moving forward on
>> the transition as quickly as practicable (so that the end users don't
>> get screwed in the long term).
> They're going to get screwed regardless in the short term because IPv6
> hasn't been deployed. NAT444 is going to be bad what ever address space
> is used between the LSN and the customer CPE.
This has a lot more to do with content not being accessible on IPv6 and
not having a solution for IPv4-only customer devices to reach IPv6
content than it does with the access networks not deploying IPv6.

The access providers generally agree that native IPv6 or 6rd can be deployed
easier and quicker than NAT444 for the problems that can solve.

The difficult comes when they deal with users, even users that have IPv6
access, that need to reach IPv4 content for whatever reason. This is where
NAT444 is pretty much the only viable alternative currently on the table.

I will note that even the people asking for this /10 are saying that they
really don't want to use it, but, they don't see any alternative.

> The proposal doesn't mention another source of unique IPv4 addresses
> that could be used for this purpose - the ISPs' existing assignments.

That's really a non-starter.

> It'll be functionally equivalent to a NAT444 /10, and will preserve
> more of the remaining public address space for purposes where truly
> globally unique IPv4 addresses are necessary. It would mean ISPs would
> have to start sharing their existing addresses sooner rather than
> later, but that is better for the customers - the longer that ISPs avoid
> introducing address sharing, the larger the shock to customers when the
> ISP can't avoid it any longer and has force customers to share
> addresses all at once. A gradual address sharing roll out would be far
> better than an abrupt one, for both the ISP and it's customers.
You're joking, right? This sounds great unless you're one of the lucky
ones that gets to go first, or, were you volunteering?

> (I'd think in principle if ARIN reserve a NAT444 /10, then the other
> RIRs would be expected to reserve a /10 or similar size in their region
> - the proposition doesn't say if the ARIN space would be usable in other
> regions. Assuming all chose a /10, that means 5 x /10s of public
> address space going in one fell swoop ...)
That's absurd. If any registry reserves a /10, I'm sure all the registries will
encourage their members to use that /10. To the best of my knowledge,
there are no plans to submit this proposal to any other registries (and
I talked to the proposal author about it the day before yesterday in

I think in principle, you really can assume that the RIRs are not insane
and won't commit wanton acts of destruction on the community.

On the other hand, what I think you will see if this policy does get bogged
down is a situation where many of the larger providers that are asking
for this will each go apply for their own allocations and they may or may
not coordinate sharing that with others. I think that is a far less desirable
alternative than getting this policy through.

> Regards,
> Mark.
>> Do you disagree?
>>> Helping ISPs avoid those costs turns the
>>> situation into one of a Moral Hazard. It won't encourage IPv6
>>> adoption; it'll delay it because both the incentive to do so, and the
>>> consequence of not doing so, are reduced.
>> Shall we encourage the patient not to hurt himself by setting the bone
>> but refusing him pain medication? Sounds positively monstrous to me.

I find myself having to agree with Bill here. I'm not 100% convinced this is
the right thing to do, and, I was pretty opposed to it from the understanding
I had of the issue when it was presented to IETF. However, at this time, I'm
leaning more towards the belief that this is one of the three things in the
IPv4 end game that we really need to just hold our noses and do.

(The first two were NRPM 8.3 and the policy for 6rd)


More information about the ARIN-PPML mailing list