[ppml] Returning blocks of IP space

Michael.Dillon at radianz.com Michael.Dillon at radianz.com
Wed Dec 4 05:43:52 EST 2002

Why are we proposing policies to return blocks of IP space?

We are arguing the nitpicking details on wording but not only is there no 
"whereas" section on these policies, nobody has suggested any good reason 
to do this. For the record, I don't believe that it is a good reason to do 
this in order to right-size an organization's allocations.

And it seems to me that this policy will result in many blocks being 
returned from the former class C range. If so, the result will be that 
ARIN will have many fragmented non-aggregatable blocks in the bank, so to 
speak. What on earth can we do with such a fragmented mess of unallocated 
IP space?

If there is, in fact, a long term plan for the reorganization and 
reallocation of the former class C ranges, then I would like to see that 
discussed in detail before we put forth any policies regarding the 
swapping of old block for new.

I believe we should be proceeding roughly as follows:

1. Assuming that there will come a time when we really do have to squeeze 
every last drop out of the IPv4 space, let's discuss and publish a plan 
for the reallocation of the space. This plan should simply assume that all 
organizations will give back the space when asked because the purpose of 
this plan is to look one step beyond the process of reclamation. I have 
suggested that this space could be subdivided into portions in which the 
largest aggregates are /24, /25, /26, /27, /28, /29 and one for /32. These 
allocations would go to organizations whose need for globally routable 
portable allocations is expected to remain rather constant over time.  But 
perhaps someone has a better plan? Let's discuss this.

2. Having reached a consensus on what to do with the space, we will also 
know which blocks need to be returned and reallocated. At this point we 
can begin a swapping program with blockholders in the former Class C 

In parallel to this:

1. Assuming that it is a good thing for all IPv4 blockholders to be 
registered with ARIN, we should undertake a program of contacting and 
signing up organizations. The fees would be based on the organization's 
justified need for IP space. If their current allocation is in the former 
class C range then there will be no change in the allocation until a plan 
for reallocation of the former class C range has been agreed. Outside of 
that range, the allocation will be rightsized by shrinking or swapping the 

2. ARIN should publish a directory, updated daily, that identifies all 
unallocated ARIN space at the largest aggregate level. This should be 
published in a form that would allow ISPs to use the directory (or a 
mirror of it) to configure their routers to filter these addresses from 
the Interner. Presumably this would be published as a BGP feed. 

In other words, there are two separate activities and they should have 
separate policies. One activity deals with allocating space and the other 
deals with getting everyone to maintain a relationship with ARIN. 

-- Michael Dillon

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