[arin-ppml] The Library Book Approach to IPv4 Scarcity

Michael Sinatra michael at rancid.berkeley.edu
Mon Oct 27 20:23:44 EDT 2008

On 10/27/08 11:52 AM, Chris Grundemann wrote:

> IP space (v4, v6, vX) is a public resource and as such should be borrowed,
> used and returned by those with a need for it. Think of IPv4 prefixes like
> library books (another finite public resource): When you check out a book,
> you are expected to return it on a certain date. If that date comes and you
> are still actively using the book, you are allowed to state that and keep
> the book. Since we are at a point now where IPv4 space is recognizably
> finite, it makes sense to implement a similar policy at the RIR(s) - that is
> a time frame. This policy would require that after X amount of time, the
> LIR/EU would need to return to the RIR with justification if they wish to
> keep the space. The burden should be on the LIR/EU to prove that they are
> actively using the space.

Just a philosophical question here: The above seems to imply that the 
expected behavior by an organization or service provider who makes the 
transition to IPv6 will eventually be to give back space as part of that 
transition.  Two alternative possibilities exist that I can think of:

2. [#1 is already listed above] Organizations that transition to IPv6 
are allowed to keep their IPv4 space (in the absence of a transfer 
market) as they transition away from it.  RIRs become less concerned 
with IPv4 as IPv6 takes hold, and eventually all IPv4 holdings become 
irrelevant.  (I realize I am condensing possibly 10-15 years into two 

3. Organizations that quickly transition to IPv6 can recoup some of the 
cost of the transition by selling IPv4 addresses in a transfer market. 
Such a market would then provide incentives for transitioning to IPv6 at 
a certain time (i.e. once enough IPv6 services and/or transition 
mechanisms exist to make it feasible, and after IPv4 free-pool runout, 
but before all of the wealthy laggards have transitioned--otherwise 
there will be no buyers) because "early-to-middle adopters" can sell 
their unused v4 space to wealthy late-adopters who need it.  Eventually 
enough entities will transition and start rolling out v6-only services 
that the laggards will find it in their best interests to transition. 
The market for IPv4 eventually collapses and nobody cares.

All three assume a largely successful transition to IPv6.  Outcomes that 
don't assume a successful transition are out of scope of this immediate 

I think that my assumption had always been that #2 and #3 were much more 
likely and feasible than #1.  It's not that I am necessarily in favor of 
a market address exchange, but I recognize that it may be a lot more 
likely to just happen than an voluntary return of resources to ARIN. 
Moreover, once IPv4 resources can no longer be monetized because IPv6 is 
the dominant protocol, returning resources to ARIN will be a waste of 
{ARIN's, the member's} time because they will basically be worthless.

I'd like to hear from other folks who think that #1 is a viable option 
and should be pursued, but at this point, I oppose the policy because I 
think it rests on a not-very-likely assumption.


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